This page is intended for a general overview of setting up Motive with force plates. Please visit the following pages for specific force plate setup from the different manufacturers:

• AMTI Force Plate Setup

• Bertec Force Plate Setup

Peripheral Device Module

In order to integrate force plate systems with Motive, you will need to setup the required drivers and plugins. Motive installer is packaged with the Peripheral Device module which can be added. During the Motive installation, a list of program features will be shown in the Custom Setup section. Here, change the setting for the Peripheral Device module, as shown in the below image, so that the module is installed along with Motive Files.

Force Plate Setup in Motive

1. Start Motive

If the hardware and software for the force plates are configured and successfully recognized, Motive will list out the detected force plates with number labels (1, 2, etc..). Motive will notify you of incorrect or nonexistent force plate calibration files. When the devices are successfully instantiated in Motive, the will indicate that the device has been created and loaded.

2. Calibrate Cameras

Calibrate the capture volume as normal to get the orientation of the cameras (see the or page for more information). The position of the force plate is about the center of the volume, and when you recalibrate or reset the ground plane, you will need to also realign the position of your force plates for best results.

3. Setup CS-400

On the , pull the force plate alignment tabs out and put the force plate leveling jigs at the bottom. The leveling jigs align the calibration square to the surface of your force plate. The alignment tabs allow you to put the CS-400 flush against the sides of your force plate giving the most accurate alignment.

4. Place CS-400 on force plate

Place the calibration wand on the force plate so that vertex of the wand is located at the right-hand corner of the side where the cable input is located (as shown in the image below). A correct placement of the calibration square is important because it determines the orientation of the force plate and its local coordinate axis within the global system. The coordinate systems for force plates are independent of the system used Motive.

5. Set force plate position in Motive.

After placing the calibration square on the force plate, select the CS-400 markers in Motive. Right click on the force plate you want to locate, and click Set Position. When there are multiple force plates in a volume, you may need to step on the force plate to find which platform the calibration square is on. In Motive, uncalibrated force plates will light up in green and a force vector will appear when you step on the plate. Repeat step 4 and 5 for other force plates as necessary.

Referencing to the markers on the calibration square, Motive defines the location of the force plate coordinate system within the global coordinate system.

Motive uses manufacturer defined X, Y, and Z mechanical-to-electrical center offset when calculating the force vector and the center of pressure. For digital based plates, this information is available from the SDK and also stored in the plate's on-board calibration data.

6. Zero force plates.

After you have calibrated each of your force plates, remove the CS-400 from the volume. Right click one of your force plates in Motive and click Zero (all). This will tare the scale and set the current force on the plate data to 0. This will account for a small constant amount of measurement offset from the force plate. Remember that it zeros all of the force plates at once. So make sure there are no objects on any of the force plates.

7. Set sampling rate

Sampling rate of force plates is configured through the synchronization setup which will be covered in the following section. You can sync the force plates either through the reference clock sync or through the triggered sync. Please note that only specific sampling rates may be supported depending on the amplifier models.

Synchronization Configuration

There are two synchronization approaches you could take: Synchronization through clock signal or through recording trigger signal.

Synchronization via clock signal utilizes the internal clock signal of the eSync to synchronize the sampling of the force plates on per-frame basis. However, when there is another device (e.g. NI-DAQ) being synchronized to the clock signal frequency, the sampling rate cannot be set for each individual device. In that case, triggered sync must be used for synchronizing the initial recording trigger. Synchronization via trigger signal utilizes the recording trigger in Motive to align the initial samples from both systems. After the initial sync, both systems run freely at their own sampling rate. If the force plates are running at whole multiples of the camera system, the collected samples will be aligned. However, since the sampling clocks are not perfectly accurate, alignment of the samples may slowly drift over time. Thus, when synchronizing via recording trigger, it is better to keep the record times short.

When synchronizing through the eSync, use the following steps to configure the sync settings in Motive. This will allow both systems to be triggered simultaneously with reference to the parent synchronization device, the eSync.

Sync Configuration Steps: eSync 2

How to Validate your Synchronization

Before you start recording, you may want to validate that the camera and force plate data are in sync. There are some tests you can do to examine this.

The first method is to record dropping a retroreflective ball/marker onto the platform few times. The bouncing ball produces a sharp transition when it hits the surface of the platform, and it makes the data more obvious for validating the synchronization. Alternately, you can attach a marker on a tip of the foot and step on and off the force plate. Make sure that your toe — closest to the marker — strikes the platform first, otherwise the data will seem off even when it is not. You can then monitor the precise timing of the ball or the foot impacting the force plate and compare them between the mocap data and the force plate data.

The following is an example of validating good synchronization outcomes:

Device Settings Profile

All of the configured device settings, including the calibration, get saved on Device Profile XML files. When you exit out of Motive, updated device profiles will be saved under the program data directory (C:\ProgramData\OptiTrack\Motive\DeviceProfiles), and this file gets loaded again when you restart Motive. You can have this file backed up to persist configured eSync and device settings. Also, if you wish to reset the device settings, you can remove XML files other than the default one from the folder, and Motive will load from the default settings.

Force Plate Data in Motive

Force plate data can be monitored from the . You will need to either use a provided Force Plate Forces layout or configure a custom graph layouts to show force plate data. To view the force plate data, make sure the corresponding force plates are selected, or selection-locked, in Motive.

If you are configuring your own force plate graph layout, make sure the desired force plate data channels (Fx, Fy, Fz, Mx, My, or Mz) are selected to be plotted. Then, when you select a force plate in Motive, and the data from the corresponding channels will be plotted on the graphs. When both reconstructed markers and force plate channels are selected, the force plot will be sub-sampled in order to be plotted along with trajectory data. For more information about how to configure graph layouts, read through the page.

Live Force Plate Data

Data Export

We recommend the following programs for analyzing exported data in biomechanics applications:

C3D Export

Motive exports tracking data and force plate data into C3D files. Exported C3D files can then be imported into a biomechanics analysis and visualization software for further processing. See the or page for more information about C3D export in Motive. Note that the coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.

C3D Axes

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

CSV Export

Force plate data and the tracking data can be exported into CSV files as well. When a Take file is exported into a CSV file. Separate CSV files will be saved for each force plate and it will contain the force, moment, and center of pressure data. Exported CSV file can be imported for analysis.

Data Streaming

To stream tracking data along with the force plate data, open the Data Streaming Pane and check the Broadcast Frame Data, and make sure that you are not streaming over the camera network. Read more about streaming from the workflow page.

Motive can stream the tracking data and the force plate data into various applications — including Matlab — using protocol. Find more about from the User's Guide included in the download.

Force Plate States

From the Devices pane, Motive reports the state of the force plate. Below is the icon associated with each state.

Overview

This page demonstrates a sample system setup involving multiple external devices. Specifically, one National Instruments Data Acquisition (NI-DAQ) device, two force plates, and a recording trigger will be integrated. Only basic step-by-step instructions will be covered in this guide. For detailed explanation of each device integrations, visit the following pages:

Requirements

• Motive

• Motive: the Peripheral Device module and the NI-DAQmx plugin (15.1.1 or later).

• Ethernet camera system with the eSync synchronization hub.

Sync Chain Setup Steps

Step 1. [Hardware Setup]

First of all, connect the external devices to the appropriate input or output ports of the eSync 2.

• NI-DAQ (child): Connect one of the Output ports of the eSync 2 to an input terminal of the USB NI-DAQ device. The input terminal must support external sample clock signals in order to sync with the clock signal from the eSync 2. When integrating bare wire DAQ devices, respective ground signals must be separated from the BNC port. Sync Signal: Internal Clock

• Force Plates (child): Connect the Output ports of the eSync 2 to a sync input port on the force plate amplifier. Sync Signal: Recording Pulse (AMTI) / Recording Gate (Bertec) for triggered sync. External clock sync cannot be used in this setup, because the clock signal will be used mainly for synchronizing the NI-DAQ device which usually runs at a faster sampling rate.

Step 2. [Hardware Setup] Connect the devices.

Connect the USB cables from the force plates and the NI-DAQ device to the host PC.

Step 3. [Software Setup] Install Peripheral Device module and NI-DAQmx driver

For integrating force plates and NI-DAQ devices, the Peripheral Device module and the NI-DAQmx driver must be installed along with Motive; both of which can be installed during the Motive installation process.

Step 4. [Motive] Launch Motive.

If the devices are properly recognized, they will be listed under the in Motive.

Step 5. Place CS-400 on force plate

Place the calibration wand on the force plate so that vertex of the wand is located at the right-hand corner of the side where the cable input is located (as shown in the image below). A correct placement of the calibration square is important because it determines the orientation of the force plate and its local coordinate axis within the global system. The coordinate systems for force plates are independent of the system used Motive.

Step 6. [Motive] Zero the devices.

Right-click on the NI-DAQ device or the force plates either on the or on the and click Zero. This will tare the devices and set the currently detected voltage/force to zero.

Step 7. [Motive → Properties: eSync]

Now, let's configure the synchronization setup. This is done through configuring the properties of the eSync. Open the and the . Select the eSync under the list of devices and its properties will be listed out in the . Here, you can adjust the properties to change the sync source, sync input/output behaviors.

Step 8. [Motive → Properties: eSync] Select the Sync Source.

First of all, you need to select and configure the sync input source. In this setup, the Internal Clock signal of the eSync will be used to synchronize the camera system. Set the Sync Input: Source to Internal Clock.

Step 9. [Motive → Properties: eSync] Configure the Sync Source.

Once the Internal Clock is selected as the sync source, configure the clock signal:

• Clock Freq (Hz): This sets the frequency of the clock signal. In this setup, the clock signal will be used to sync the camera system frame rate and also the acquisition rate of the NI-DAQ devices. Since the NI-DAQ devices usually sample at a higher frame rate, first set the clock frequency to the desired NI-DAQ sampling rate and apply input divider and multiplier for the camera system.

• Input Trigger/Divider/Multiplier: Adjust the input divider and multiplier to derive the camera system frame rate from the configured internal clock signal. The final frame rate will be displayed at the bottom of the Sync Input section. Only the supported camera frame rate can be applied.

Step 10. [Motive → Properties: eSync 2] Configure the Sync Outputs.

Now, configure the output signal into the child devices. Configure the corresponding output port that each device is connected.

• NI-DAQ: Set the output type of the connected output port to Gated Internal Clock signal. This will set the eSync 2 so that the internal clock is sent out when Motive starts recording.

• Force Plates: Set the output type of the connected output port to Recording Gate (Bertec) or Recording Pulse (AMTI). The force plate systems will synchronize with the recording trigger from the eSync 2.

Step 11. [Motive: → Properties: eSync]] Configure the Remote Trigger device.

Now let's configure the Record Trigger device. Under the Record Triggering section, set the trigger source to the input port that the device is connected to, and select appropriate trigger edge depending on the morphology of the trigger signal.

Step 12. [Motive: → Properties: eSync]] Apply the configuration.

Now that the eSync properties have been configured, the sync chain of the connected devices should be set up. Next step is to configure the properties of the external devices.

Step 13. [Motive → Properties: NI-DAQ] Configure NI-DAQ properties in Motive

Click on the NI-DAQ device under the and open the to configure its sync properties. The following configuration sets the NI-DAQ devices to synchronize its data acquisition with the clock signal from the eSync.

• Use External Clock: True.

• NIDAQExternalClockTerminal: Designate input channel of the NI-DAQ.

• SyncMode: Free Run.

Step 14. [Motive → Properties: Force Plate]

Click on the Force Plate device under the and open the to configure its sync properties. The following configuration sets the force plates to trigger sync to the recording signal from the eSync 2:

• Record Trigger: Device

• Use External Clock: False

• Sync Mode: Free Run

Step 15. [Motive]

Now the systems are synchronized. When you start recording in Motive, precisely aligned data will be collected.

Step 16. [Motive] Recording Trigger.

To utilize the external recording trigger device, press the record button in Motive and set it to a standby mode. Then use the device to send the recording trigger to the eSync 2, which will either initiate or stop recording each time a trigger is received.

Example force plate properties for triggered sync.This page provides instructions on integrating an AMTI Force plate system with an OptiTrack motion capture system.

Overview

When a motion capture system is used in conjunction with force plates, they work together as an efficient tool for various research applications including biomechanical analysis, clinical gait analysis, physiology research, sports performance research, and many more. An OptiTrack motion capture system can synchronize with force plates to obtain both kinematic and kinetic measurements. Note that force plate integration is supported only with a Prime camera system using the eSync 2 synchronization hub. This page provides quick guidelines for setting up and configuring force plates — with digital outputs — along with the OptiTrack motion capture system.

For detailed information on specifications and configurations on the force plates, refer to the documentation provided by the force plate manufacturer.

Required Components

• Supported Amplifier Models: AMTI Gen 5, AMTI Optima.

• Force platforms that are compatible with the above amplifier models.

• Prime series Ethernet camera system with the eSync synchronization hub.

Hardware Setup

Component Wiring (AMTI)

AMTI Force Plate System Setup

Connect each force plate into the host PC. For force plate systems with external amplifiers, the platform must be connected to the amplifier which uplinks to the host computer. For detailed instructions on setting up the Force Plate system with a host PC, refer to the AMTI documentation.

Camera System Setup

Setup the OptiTrack camera system and place the force plate(s) at the desired location(s); ideally, near the center of the volume. See or page for details.

Wiring the eSync with the Gen 5 Amplifier

For accurate synchronizations, the must be used. The eSync 2 has signal output ports that are used to send out synchronization signals to child devices. Connect the BNC output ports of the eSync to sync input ports (Genlock/Trigger Input) of force plate amplifiers.If force plate systems have RCA sync ports, use RCA cables along with the 50 Ohm BNC Male to 75 Ohm RCA Jack Adapters included with the eSync 2 to connect the amplifiers. The above wiring diagram shows how force plate systems need to be connected to an Ethernet camera system through the eSync 2.

Multiple Devices Sync

There are total four output ports on the eSync 2, and multiple force plates and external devices can be integrated if needed. Consult our for multiple force plate synchronizations.

Hot Plugging

Software Setup

AMTI Software Setup

Before setting up the force plates in Motive, make sure software components required by the force plate system is installed on the computer. AMTI's software (e.g. AMTINetForce) must be able to detect and initialize the connected devices in order for the force plates to be properly initialized and used in Motive. Once this has been confirmed working, start setting up Motive. Please refer to manufacturer documentation for more information.

Peripheral Device Module

In order to integrate force plate systems with Motive, you will need to setup the required drivers and plugins. Motive installer is packaged with the Peripheral Device module which can be added. During the Motive installation, a list of program features will be shown in the Custom Setup section. Here, change the setting for the Peripheral Device module, as shown in the below image, so that the module is installed along with Motive Files.

Force Plate Setup in Motive

1. Start Motive

If the hardware and software for the force plates are configured and successfully recognized, Motive will list out the detected force plates with number labels (1, 2, etc..). Motive will notify you of incorrect or nonexistent force plate calibration files. When the devices are successfully instantiated in Motive, the will indicate that the device has been created and loaded.

2. Calibrate Cameras

Calibrate the capture volume as normal to get the orientation of the cameras (see the or page for more information). The position of the force plate is about the center of the volume, and when you recalibrate or reset the ground plane, you will need to also realign the position of your force plates for best results.

3. Setup CS-400

On the , pull the force plate alignment tabs out and put the force plate leveling jigs at the bottom. The leveling jigs align the calibration square to the surface of your force plate. The alignment tabs allow you to put the CS-400 flush against the sides of your force plate giving the most accurate alignment.

4. Place CS-400 on force plate

Place the calibration wand on the force plate so that vertex of the wand is located at the right-hand corner of the side where the cable input is located (as shown in the image below). A correct placement of the calibration square is important because it determines the orientation of the force plate and its local coordinate axis within the global system. The coordinate systems for force plates are independent of the system used Motive.

5. Set force plate position in Motive.

After placing the calibration square on the force plate, select the CS-400 markers in Motive. Right click on the force plate you want to locate, and click Set Position. When there are multiple force plates in a volume, you may need to step on the force plate to find which platform the calibration square is on. In Motive, uncalibrated force plates will light up in green and a force vector will appear when you step on the plate. Repeat step 4 and 5 for other force plates as necessary.

Referencing to the markers on the calibration square, Motive defines the location of the force plate coordinate system within the global coordinate system.

Motive uses manufacturer defined X, Y, and Z mechanical-to-electrical center offset when calculating the force vector and the center of pressure. For digital based plates, this information is available from the SDK and also stored in the plate's on-board calibration data.

6. Zero force plates.

After you have calibrated each of your force plates, remove the CS-400 from the volume. Right click one of your force plates in Motive and click Zero (all). This will tare the scale and set the current force on the plate data to 0. This will account for a small constant amount of measurement offset from the force plate. Remember that it zeros all of the force plates at once. So make sure there are no objects on any of the force plates.

7. Set sampling rate

Sampling rate of force plates is configured through the synchronization setup which will be covered in the following section. You can sync the force plates either through the reference clock sync or through the triggered sync. Please note that only specific sampling rates may be supported depending on the amplifier models.

Synchronization Configuration

There are two synchronization approaches you could take: Synchronization through clock signal or through recording trigger signal.

Synchronization via clock signal utilizes the internal clock signal of the eSync to synchronize the sampling of the force plates on per-frame basis. However, when there is another device (e.g. NI-DAQ) being synchronized to the clock signal frequency, the sampling rate cannot be set for each individual device. In that case, triggered sync must be used for synchronizing the initial recording trigger. Synchronization via trigger signal utilizes the recording trigger in Motive to align the initial samples from both systems. After the initial sync, both systems run freely at their own sampling rate. If the force plates are running at whole multiples of the camera system, the collected samples will be aligned. However, since the sampling clocks are not perfectly accurate, alignment of the samples may slowly drift over time. Thus, when synchronizing via recording trigger, it is better to keep the record times short.

When synchronizing through the eSync, use the following steps to configure the sync settings in Motive. This will allow both systems to be triggered simultaneously with reference to the parent synchronization device, the eSync.

Sync Configuration Steps: eSync 2

How to Validate your Synchronization

Before you start recording, you may want to validate that the camera and force plate data are in sync. There are some tests you can do to examine this.

The first method is to record dropping a retroreflective ball/marker onto the platform few times. The bouncing ball produces a sharp transition when it hits the surface of the platform, and it makes the data more obvious for validating the synchronization. Alternately, you can attach a marker on a tip of the foot and step on and off the force plate. Make sure that your toe — closest to the marker — strikes the platform first, otherwise the data will seem off even when it is not. You can then monitor the precise timing of the ball or the foot impacting the force plate and compare them between the mocap data and the force plate data.

The following is an example of validating good synchronization outcomes:

Device Settings Profile

All of the configured device settings, including the calibration, get saved on Device Profile XML files. When you exit out of Motive, updated device profiles will be saved under the program data directory (C:\ProgramData\OptiTrack\Motive\DeviceProfiles), and this file gets loaded again when you restart Motive. You can have this file backed up to persist configured eSync and device settings. Also, if you wish to reset the device settings, you can remove XML files other than the default one from the folder, and Motive will load from the default settings.

Force Plate Data in Motive

Force plate data can be monitored from the . You will need to either use a provided Force Plate Forces layout or configure a custom graph layouts to show force plate data. To view the force plate data, make sure the corresponding force plates are selected, or selection-locked, in Motive.

If you are configuring your own force plate graph layout, make sure the desired force plate data channels (Fx, Fy, Fz, Mx, My, or Mz) are selected to be plotted. Then, when you select a force plate in Motive, and the data from the corresponding channels will be plotted on the graphs. When both reconstructed markers and force plate channels are selected, the force plot will be sub-sampled in order to be plotted along with trajectory data. For more information about how to configure graph layouts, read through the page.

Live Force Plate Data

Data Export

We recommend the following programs for analyzing exported data in biomechanics applications:

C3D Export

Motive exports tracking data and force plate data into C3D files. Exported C3D files can then be imported into a biomechanics analysis and visualization software for further processing. See the or page for more information about C3D export in Motive. Note that the coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.

C3D Axes

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

CSV Export

Force plate data and the tracking data can be exported into CSV files as well. When a Take file is exported into a CSV file. Separate CSV files will be saved for each force plate and it will contain the force, moment, and center of pressure data. Exported CSV file can be imported for analysis.

Data Streaming

To stream tracking data along with the force plate data, open the Data Streaming Pane and check the Broadcast Frame Data, and make sure that you are not streaming over the camera network. Read more about streaming from the workflow page.

Motive can stream the tracking data and the force plate data into various applications — including Matlab — using protocol. Find more about from the User's Guide included in the download.

This page provides instructions on how to set up, configure, and use the Prime Color video camera.

Overview

Prime Color

The Prime Color is a full-color video camera that is capable of recording synchronized high-speed and videos. It can also be hooked up to a mocap system and used as a reference camera. The camera enables recording of high frame rate videos (up to 500 FPS at 480p) with resolutions up to 1080p (at 250 FPS) by performing onboard compression (H.264) of captured frames. It connects to the camera network and receives power by a standard PoE connection.

eStrobe

When capturing high-speed videos, the time-length of camera exposures are very short, and thus, providing sufficient lighting becomes critical for obtaining clear images. The eStrobe is designed to optimally brighten the image taken by Prime Color camera by precisely synchronizing the illuminations of the eStrobe LEDs to each camera exposure. This allows the LEDs to illuminate at a right timing, producing the most efficient and powerful lighting for the high-speed video capture. Also, the eStrobe emits white light only, and it will not interfere with the tracking within the IR spectrum.

Computer Requirements

General Requirements

Required PC specifications may vary depending on the size of the camera system. Generally, you will be required to use the recommended specs with a system with more than 24 cameras.

Graphics Card

For using Prime Color cameras, it requires the computer to be equipped with a dedicated graphics card that has a performance of GTX 1050, or better, with the latest driver that supports OpenGL version 4.0 or higher.

Storage Capacity

Since each color camera can upload a large amount of data over the network, the size of the recorded Take (TAK) can get pretty large even with a short recording. For example, if a 10-second take was recorded with a total data throughput of 1-GBps, the resulting TAK file will be 10-GB, and it can quickly fill up the storage device. Please make sure there is enough capacity available on the disk drive. If you are exporting out the recorded data onto video files after they are captured, re-encoding the videos will help with reducing the files magnitudes smaller. See:

Write Speed

Since Prime Color cameras can output a large amount of data to the RAM memory quickly, it is also important that the write-out speed to the storage is also fast enough. If the write-out speed to secondary drive isn't fast enough, the occupied memory in RAM storage may gradually increase to its . For recording with just a one or two Prime Color cameras, standard SSD drive will do its job. However, when using multiple Prime Color cameras, it is recommended to use a fast storage drive (e.g. M.2 SSD) that can quickly write out the recorded capture that from the RAM.

Network Card

When running two or more Prime Color cameras, the computer must have a 10-gigabit network adapter in order to successfully receive all of the data outputted from the camera system. Please see section for more information.

Hardware Setup

Camera Lens

Different types of lenses can be equipped on a Prime Color camera as long as the lens mount is compatible, however, for Prime Color cameras, we suggest using C-mount lenses to fully utilize the imager. Prime Color cameras with C-mount can be equipped with either the 12mm F#1.8 lenses or the 6.8mm F#1.6 lenses. The 12mm lens is zoomed in more and is more suitable for capturing at long ranges. On the other hand, the 6.8mm lens has a larger field of view and is more suitable for capturing a wide area. Both lenses have adjustable f-stop and focus settings, which can be optimized for different capture environments and applications.

• F-Stop: Set the f-stop to a low value to make the aperture size bigger. This will allow in more light onto the imager, improving the image quality. However, this may also decrease the camera's depth of field, requiring the lens to be focused specifically on the target capture area.

• Focus: For best image quality, make sure the lenses are focused on the target tracking area.

Load Balancing

Data Bandwidth

Before going into details of setting up a system with Prime Color cameras, it is important to go over the data bandwidth availability within the camera network. At its maximum setting for capturing the best quality image, one Prime Color camera can transmit data at a rate of up to ~100 Megabytes-per-second (MBps), or ~800 Megabits-per-second (Mbps). For a comparison, a tracking camera in outputs data at a rate less than 1MBps, which is several magnitudes smaller than the output from a Prime Color camera. A standard network switch (1 Gb switch) and network card only support network traffic of up to 1000 Mbps (or 1 Gbps). When Prime Color camera(s) are used, they can take up a large portion, or all, of the available bandwidth, and for this reason, extra attention to bandwidth use will be needed when first setting up the system.

When there is not enough available bandwidth, captured 2D frames may drop out due to the data bottleneck. Thus, it is important to take the bandwidth consumption into account and make sure an appropriate set of network switches (PoE and Uplink), Ethernet cables, and a network card is used. If a 1-Gb network/uplink switch is used, then only one Prime Color camera can be used at its maximum bit-rate setting. If two or more Prime Color cameras need to be used, then either a 10-Gb network setup will be required OR the setting will need to be turned down. A lower bit-rate will further compress the image with a tradeoff on the image quality, which may or may not be acceptable depending on the capture application.

Cabling

Power

Each Prime Color camera must be uplinked and powered through a standard PoE connection that can provide at least 15.4 watts to each port simultaneously.

eStrobes

eStrobe Setup

The eStrobe synchronizes with Prime Color cameras through RCA cable connection. It receives exposure signals from the cameras and synchronizes its illuminations correspondingly. Depending on the frame rate of the camera system, the eStrobe will vary its illumination frequency, and it will also vary the percent duty cycle depending on the exposure length. Multiple eStrobes can be daisy-chained in series by relaying the sync signal from the output port to the input port of another as shown in the diagram.

Capturing without eStrobes

When capturing without eStrobes, the camera entirely relies on the ambient lighting to capture the image, and the brightness of the captured frames may vary depending on which type of light source is used. In general, when capturing without an eStrobe, we recommend setting the camera at a lower framerate (30~120 FPS) and increasing the camera exposure to allow for longer exposure time so that the imager can take in more light.

Indoor

When capturing indoors without the eStrobe, you will be relying on the room lighting for brightening up the volume. Here, it is important to note that every type of artificial light source illuminates, or flickers, at a certain frequency (e.g. fluorescent light bulbs typically flicker at 120Hz). This is usually fast enough so that the flickering is not noticeable to human eyes, however, with high-speed cameras, the flickering may become apparent.

When Prime Color captures at a frame rate higher than the ambient illumination frequency, you will start noticing brightness changes between consecutive frames. This happens because, with mismatching frequencies, the cameras are exposing at different points of the illumination phase. For example, if you capture at 240FPS with 120Hz light bulbs lighting up the volume, brightness of captured images may be different in even and odd numbered frames throughout the capture. Please take this into consideration and provide appropriate lighting as needed.

Outdoor

When capturing outdoors using Prime Color cameras, sunlight will typically provide enough ambient lighting. Unlike light bulbs, sunlight is emitted continuously, so there is no need to worry about the illumination frequency. Furthermore, the sun is bright enough and you should be able to capture high-quality images by adjusting only the f-stop (aperture size) and the exposure values.

Setup Check-Point

Now that you have set up a camera system with Prime Color, all of the connected cameras should be listed under the . At this point, you would want to launch Motive and check the following items to make sure your system is operating properly.

• 2D Frame Delivery: There should be no dropped 2D frames. You can monitor this under the or from the . If frame drops are reported continuously, you can lower down the setting or revisit the network configuration and make sure the data loads are balanced out. For more information, section of this page.

• CPU Usage: Open the windows task manager and check the CPU processing load. If only one of the CPU core is fully occupied, the CPU is not fast enough to process data from the color camera. In this case, you will want to use a faster CPU or lower down the setting.

Camera Settings

When you launch Motive, connected Prime Color cameras will be shown in Motive, and you will be able to configure the settings as you would do for other tracking cameras. Open up the and the , and select a Prime Color camera(s). On the Properties pane, key properties that are specific to the selected color cameras will be listed. Optimizing these settings are important in order to obtain best quality images without overflooding the network bandwidth. The key settings for the color cameras are image resolution, gamma correction, as well as compression mode and bit-rate settings, which will be covered in the following sections.

Camera Resolution

Default: 1920, 1080

This property sets the resolution of the images that are captured by selected cameras. Since the amount of data increases with higher resolution, depending on which resolution is selected, the maximum allowable frame rate will vary. Below is the maximum allowed frame rates for each respective resolution setting.

Compression Mode

Default: Constant Bit Rate.

This property determines how much the captured images will be compressed. The Constant Bit-Rate mode is used by default and recommended because it is easier to control the data transfer rate and efficiently utilize the available network bandwidth.

Constant Bit-Rate

In the Constant Bit-Rate mode, Prime Color cameras vary the degree of image compression to match the data transmission rate given under the Bit Rate settings. At a higher bit-rate setting, the captured image will be compressed less. At a lower bit-rate setting, the captured image will be compressed more to meet the given data transfer rate, but compression artifacts may be introduced if it is set too low.

Variable Bit-Rate

Variable Bit-Rate setting is also available for keeping the amount of the compression constant and allowing the data transfer rate to vary. This mode can be beneficial when capturing images with objects that have detailed textures because it keeps the amount of compression same on all frames. However, this may introduce dropped frames whenever the camera tries to compress highly detailed images because it will increase the data transfer rate; which may overflow the network bandwidth as a result. For this reason, we recommend using the Constant Bit-Rate setting in most applications.

Bit-rate

Default: 50

Available only while using Constant Bit-rate Mode

Bit-rate setting determines the transmission rate outputted from the selected color camera. The value given under this setting is measured in percentage (100%) of the maximum data transmission speed, and each color camera can output up to ~100 MBps. In other words, the configured value will indirectly represent the transmission rate in Megabytes per second (MBps). At bit-rate setting of 100, the camera will capture the best quality image, however, it could overload the network if there is not enough bandwidth to handle the transmitted data.

Since the bit-rate controls the amount of data outputted from each color camera, this is one of the most important settings when properly configuring the system. If your system is experiencing 2D frame drops, it means one of the system requirements is not met; either network bandwidth, CPU processing, or RAM/disk memory. In such cases, you could decrease the bit-rate setting and reduce the amount of data output from the color cameras.

Image Quality

The image quality will increase at a higher bit-rate setting because it records a larger amount of data, but this will result in large file sizes and possible frame drops due to data bandwidth bottleneck. Often, the desired result is different depending on the capture application and what it is used for. The below graph illustrates how the image quality varies depending on the camera framerate and bit-rate settings.

Gamma

Default : 24

Gamma correction is a non-linear amplification of the output image. The gamma setting will adjust the brightness of dark pixels, midtone pixels, and bright pixels differently, affecting both brightness and contrast of the image. Depending on the capture environment, especially with a dark background, you may need to adjust the gamma setting to get best quality images.

LED

Default: On

If you are using the to light up the capture volume, the LED setting must be enabled on the Prime Color cameras which the eStrobes connect to. When this setting is enabled, the Prime Color camera will start outputting the signals from its RCA sync output port, allowing the eStrobes to receive this signal and illuminate the LEDs.

Calibration

In order to calibrate the color camera into the 3D capture volume, the Prime Color camera must be equipped with an IR filter switcher. Prime Color cameras without IR filter switcher cannot be calibrated, and can only be used as a reference camera to monitor the reference views in the or in the .

Prime Color FS Calibration

The Prime Color FS is equipped with a filter switcher that allows the cameras to detect in IR spectrum. The Prime Color FS can be calibrated into the 3D capture volume using an active calibration wand with the IR LEDs. Once calibrated, the color camera will be placed within the 3D viewport along with other tracking cameras, and 3D assets (markers, Rigid Bodies, Skeletons, cameras) can be overlaid as shown in the image.

To calibrate the camera, switch the Prime Color FS to the in the pane. This will switch the Color camera to detect in the IR spectrum, and then use the active wand to follow the standard process. Once the calibration is finished, you can switch the camera back to the Color Video Mode.

Data Recording / Export

Once you have set up the system and configured the cameras correctly, Motive is now ready to capture Takes. Recorded TAK files will contain color video along with the tracking data, and you can play them back in Motive. Also, the color reference video can be exported out from the TAK.

Data Recording

Once the camera is set up, you can start recording from Motive. Captured frames will be stored within the TAK file and you can access them again in Edit mode. Please note that capture files with Prime Color video images will be much larger in file size.

Video Export

Once the color videos have been saved onto TAK files, the captured reference videos can be exported into AVI files using either H.264 or MJPEG compression format. The H.264 format will allow faster export of the recorded videos and is recommended. Video for the current TAK can be exported by clicking File tab -> Export Video option in Motive, or you can also export directly from the by right-clicking on the Take(s) and clicking Export Video from the context menu. The following export dialogue window will open and you will be able to configure the export settings before outputting the files:

Dropped Frames

When this is set to Drop Frames, Motive will remove any dropped frames in the color video upon export. Please note that any dropped frames will be completely removed in this case, and thus, the exact frames in the exported file may not match the frames in the corresponding Motive recording. If needed, you can set this export option to Black Frame to insert black, or blank, frames in place of the dropped frames in the exported video.

Exporting from Multiple TAKs

If there are multiple TAK files containing reference video recordings, you can export the videos all at once in the or through the . When exporting directly from the Data pane, simply CTRL-select multiple TAK files together, right-click to bring up the context menu, and click Export Video. When using the batch processor (NMotive), the VideoExporter class can be used to export videos from loaded TAK files.

Re-encoding Exported Video

The size of the exported video file can be re-encoded and compressed down further by additional subsampling. This can be achieved using a third-party video processing software, and doing so can hugely reduce the size of the exported file; almost in orders of two magnitudes. This is supported by most of the high-end video editing software, but Handbrake () is a freely available open-source software that is also capable of doing this. Since the exported video file can be large in size, we suggest using one of the third-party software to re-encode the exported video file.

FAQ / Troubleshooting

Configuring force plate sampling rate from Devices pane.This page provides instructions on how to integrate a Bertec force plate system with an OptiTrack motion capture system.

Overview

When a motion capture system is used in conjunction with force plates, they work together as an efficient tool for various research applications including biomechanical analysis, clinical gait analysis, physiology research, sports performance research, and many more. An OptiTrack motion capture system can synchronize with force plates to obtain both kinematic and kinetic measurements. Note that force plate integration is supported only with a Prime camera system using the eSync synchronization hub. This page provides quick guidelines for setting up and configuring force plates — with digital outputs — along with the OptiTrack motion capture system.

For detailed information on specifications and configurations on the force plates, refer to the documentation provided by the force plate manufacturer.

Requirements

• Supported Amplifier Models: AM6800

• Firmware Version: For synchronization support, the Bertec amplifiers must be installed with firmware version 4.5.2. The current firmware version gets displayed on the amplifier display when first powering up the amplifier. Please check this and make sure the firmware is updated to the supported versions.

• Prime series Ethernet camera system with the eSync synchronization hub.

Important Notes

• Bertec amplifiers currently only support a fixed sampling rate of 1000 Hz

Hardware Setup

Bertec Force Plate System Setup

Refer to the respective Bertec system user documentation for detailed information on setting up the force plate system and connecting to the host PC.

Camera System Setup

Set up an OptiTrack system. Connect the camera system to the same host PC. For more information, refer to the page or the pages.

Wiring the eSync with the Amplifier

Software Setup

Peripheral Device Module

In order to integrate force plate systems with Motive, you will need to setup the required drivers and plugins. Motive installer is packaged with the Peripheral Device module which can be added. During the Motive installation, a list of program features will be shown in the Custom Setup section. Here, change the setting for the Peripheral Device module, as shown in the below image, so that the module is installed along with Motive Files.

Bertec Customers

In addition to the Peripheral Device module, you may also want to install the Digital Acquire™ from Bertec to verify that the force plates are properly working. Visit the below webpage to download the software, and follow the respective instructions to install. This software installs remaining resources for connecting the Bertec force plates.

• Link:

Force Plate Setup in Motive

1. Start Motive

If the hardware and software for the force plates are configured and successfully recognized, Motive will list out the detected force plates with number labels (1, 2, etc..). Motive will notify you of incorrect or nonexistent force plate calibration files. When the devices are successfully instantiated in Motive, the will indicate that the device has been created and loaded.

2. Calibrate Cameras

Calibrate the capture volume as normal to get the orientation of the cameras (see the or page for more information). The position of the force plate is about the center of the volume, and when you recalibrate or reset the ground plane, you will need to also realign the position of your force plates for best results.

3. Setup CS-400

On the , pull the force plate alignment tabs out and put the force plate leveling jigs at the bottom. The leveling jigs align the calibration square to the surface of your force plate. The alignment tabs allow you to put the CS-400 flush against the sides of your force plate giving the most accurate alignment.

4. Place CS-400 on force plate

Place the calibration wand on the force plate so that vertex of the wand is located at the right-hand corner of the side where the cable input is located (as shown in the image below). A correct placement of the calibration square is important because it determines the orientation of the force plate and its local coordinate axis within the global system. The coordinate systems for force plates are independent of the system used Motive.

5. Set force plate position in Motive.

After placing the calibration square on the force plate, select the CS-400 markers in Motive. Right click on the force plate you want to locate, and click Set Position. When there are multiple force plates in a volume, you may need to step on the force plate to find which platform the calibration square is on. In Motive, uncalibrated force plates will light up in green and a force vector will appear when you step on the plate. Repeat step 4 and 5 for other force plates as necessary.

Referencing to the markers on the calibration square, Motive defines the location of the force plate coordinate system within the global coordinate system.

Motive uses manufacturer defined X, Y, and Z mechanical-to-electrical center offset when calculating the force vector and the center of pressure. For digital based plates, this information is available from the SDK and also stored in the plate's on-board calibration data.

6. Set the Force Plate Dimension

If the force plate dimensions are not automatically configured, you need to enter the dimensions of the force plate in the force plate properties after calibrating its positions. Go to the and select the force plate, and its properties will get listed under the . Enter the length and width (in meters) values for the corresponding plates as reported in the specifications.

7. Zero force plates.

After you have calibrated each of your force plates, remove the CS-400 from the volume. Right click one of your force plates in Motive and click Zero (all). This will tare the scale and set the current force on the plate data to 0. This will account for a small constant amount of measurement offset from the force plate. Remember that it zeros all of the force plates at once. So make sure there are no objects on any of the force plates.

8. Set sampling rate

Sampling rate of force plates is configured through the synchronization setup which will be covered in the following section. You can sync the force plates either through the reference clock sync or through the triggered sync. Please note that only specific sampling rates may be supported depending on the amplifier models.

Synchronization Configuration

There are two synchronization approaches you could take: Synchronization through clock signal or through recording trigger signal.

Synchronization via clock signal utilizes the internal clock signal of the eSync 2 to synchronize the sampling of the force plates on per-frame basis. However, when there is another device (e.g. NI-DAQ) being synchronized to the clock signal frequency, the sampling rate cannot be set for each individual device. In that case, triggered sync must be used for synchronizing the initial recording trigger. Synchronization via trigger signal utilizes the recording trigger in Motive to align the initial samples from both systems. After the initial sync, both systems run freely at their own sampling rate. If the force plates are running at whole multiples of the camera system, the collected samples will be aligned. However, since the sampling clocks are not perfectly accurate, alignment of the samples may slowly drift over time. Thus, when synchronizing via recording trigger, it is better to keep the record times short.

When synchronizing through the eSync 2, use the following steps to configure the sync settings in Motive. This will allow both systems to be triggered simultaneously with reference to the parent synchronization device, the eSync 2.

Sync Configuration Steps: eSync 2

How to Validate your Synchronization

Before you start recording, you may want to validate that the camera and force plate data are in sync. There are some tests you can do to examine this.

The first method is to record dropping a retroreflective ball/marker onto the platform few times. The bouncing ball produces a sharp transition when it hits the surface of the platform, and it makes the data more obvious for validating the synchronization. Alternately, you can attach a marker on a tip of the foot and step on and off the force plate. Make sure that your toe — closest to the marker — strikes the platform first, otherwise the data will seem off even when it is not. You can then monitor the precise timing of the ball or the foot impacting the force plate and compare them between the mocap data and the force plate data.

The following is an example of validating good synchronization outcomes:

Device Settings Profile

All of the configured device settings, including the calibration, get saved on Device Profile XML files. When you exit out of Motive, updated device profiles will be saved under the program data directory (C:\ProgramData\OptiTrack\Motive\DeviceProfiles), and this file gets loaded again when you restart Motive. You can have this file backed up to persist configured eSync and device settings. Also, if you wish to reset the device settings, you can remove XML files other than the default one from the folder, and Motive will load from the default settings.

Force Plate Data in Motive

Force plate data can be monitored from the . You will need to either use a provided Force Plate Forces layout or configure a custom graph layouts to show force plate data. To view the force plate data, make sure the corresponding force plates are selected, or selection-locked, in Motive.

If you are configuring your own force plate graph layout, make sure the desired force plate data channels (Fx, Fy, Fz, Mx, My, or Mz) are selected to be plotted. Then, when you select a force plate in Motive, and the data from the corresponding channels will be plotted on the graphs. When both reconstructed markers and force plate channels are selected, the force plot will be sub-sampled in order to be plotted along with trajectory data. For more information about how to configure graph layouts, read through the page.

Live Force Plate Data

Data Export

We recommend the following programs for analyzing exported data in biomechanics applications:

C3D Export

Motive exports tracking data and force plate data into C3D files. Exported C3D files can then be imported into a biomechanics analysis and visualization software for further processing. See the or page for more information about C3D export in Motive. Note that the coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.

C3D Axes

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

CSV Export

Force plate data and the tracking data can be exported into CSV files as well. When a Take file is exported into a CSV file. Separate CSV files will be saved for each force plate and it will contain the force, moment, and center of pressure data. Exported CSV file can be imported for analysis.

Data Streaming

To stream tracking data along with the force plate data, open the Data Streaming Pane and check the Broadcast Frame Data, and make sure that you are not streaming over the camera network. Read more about streaming from the workflow page.

Motive can stream the tracking data and the force plate data into various applications — including Matlab — using protocol. Find more about from the User's Guide included in the download.

Overview

OptiTrack motion capture systems support the integration of National Instruments data acquisition (NI-DAQ) devices. Through NI-DAQ devices, signals from various analog devices (e.g. transducers or EMG sensors) can be converted into digital signals at a user-defined sampling frequency, and they can be precisely synchronized with the motion tracking data. This page provides instructions on connecting NI-DAQ devices and acquiring analog signals within Motive.

For a list of supported models, please refer to the Supported NI-DAQ Models section of this page.

For instructions specific to the NI-DAQ devices, please refer to the respective product User Guide or the NI's .

Required Components

• OptiTrack motion capture system

• The eSync 2 synchronization hub

• Motive version 1.10 and above with a valid software license.

Additional Notes

• The NI-DAQ functionalities are not supported with the use of the Motive API.

• For integration of digital force plates, follow the guide. Analog platforms can be integrated through a NI-DAQ, but only raw voltage signals can be detected and the force plate features within Motive will not be supported.

• Up to 32 analog channels are supported for each NI-DAQ device. If you wish to use higher channel counts, please for more details.

Hardware Setup

Motive supports PCI and USB data acquisition devices from National Instruments, and the NI-DAQmx driver must be installed on the computer in order to use the devices. The driver setup instructions will be covered in the software setup section of this page. A list of supported models can be found in the section below.

Supported National Instruments Devices

Below is the list of NI-DAQ device models that are supported with Motive. For best compatibility, use the recommended models or verified models since they are most tested to work with Motive. Unverified models are expected to work as well, but their integration has not been tested yet.

NaturalPoint Recommended Devices

• USB-63XX X-Series

Verified Devices

• USB-6341, USB-6351, USB-6361

• USB-6002

• USB 6281 (M Series)

Unverified Devices

Unsupported Devices

Compact DAQ systems are not supported.

USB NI-DAQ Device Wiring Setup

The following diagrams show wiring setups for connecting and synchronizing NI-DAQ devices with Prime series motion capture systems. Please note that NI-DAQ devices can be synchronized either through reference clock sync or through recording trigger sync, and both approaches are shown below. For most precise synchronization, using external clock signal as the reference is recommended.

Software Setup

For Motive to communicate with NI-DAQ devices, the OptiTrack Peripheral Modules must be installed along with Motive and NI-DAQ device drivers. The OptiTrack Peripherals Module is a software plugin package that installs required drivers and plugin DLLs for integrating external devices, including NI-DAQ devices and force plates (AMTI and Bertec). The following section describes the steps on integrating NI-DAQ device(s) within Motive.

Installation Steps

1. Install the Peripherals Device module

During the Motive installation process, optional program features will be listed in the Custom Setup section. Here, change the setting for the Peripherals Device, as shown in the below image, so that the module is installed along with Motive.

2. Install the NI-DAQ device drivers

After agreeing to install the Peripheral Device, the installer will ask to install NI-DAQmx 15.1.1 driver. You will need to install this driver for MS Windows to recognize the connected NI-DAQ devices. Press Yes to initiate the NI-DAQmx installation and follow the instructions to set up the driver.

3. Check device connection

Ensure the NI-DAQ device is powered and detected by MS Windows. For USB DAQ devices, you could also use the installed software to confirm and monitor the connection. The NI Device Monitor can be accessed from the Windows taskbar tray when a USB DAQ device is connected.

4. Launch Motive

In the , all of the connected NI-DAQ devices will be listed along with respective analog input channels (up to 32) under the Data Acquisition group.

5. Verify device operation

Once the NI-DAQ device is recognized properly, you will be able to observe the real-time signal on the .

First, make sure the NI-DAQ device and its operating analog input channels are enabled under the . Then, open the and create a custom layout for monitoring live-analog data; create a new layout, right-click on the graphs, and select the device channel you wish to plot. Then, open the graph editor () and make sure View Style is set to Live under the Visuals tab. Configured analog channels will be plotted on the graphs.

a. Device Pane: Select a NI-DAQ channel with an active signal.

b. Device Pane: Toggle the NI-DAQ device to begin sampling.

c. Device Pane: Select the active channel.

d. Graph Pane: Show the 'Scope' View.

6. Zero the DAQ device

Detected voltage signals from a NI-DAQ input channels can be zeroed. Right-click on a NI-DAQ device from the and click Zero. Doing this will zero all of the enabled channels for the selected NI-DAQ device.

NI-DAQ Settings

Now that the device is detected in Motive, you can select and configure settings for the device and its analog channels through Motive. When a data acquisition device or an analog channel is selected in the , their respective properties will be displayed on the or on a separate pop-up for the analog channels.

Device Properties

Properties of connected NI-DAQ devices get listed in the when a device is selected in the . These properties need to be configured in order to properly synchronized the data acquisition device and the camera system together. Details about appropriate property settings will be covered in the following section.

Device Channel Properties

Properties of individual channels can be configured directly from the . As shown in the image, you can click on the icon to bring up the settings and make changes.

Depending on the model, NI-DAQ devices may have different sets of allowable input types and voltage ranges for their analog channels. Refer to your NI-DAQ device User's Guide for detailed information about supported signal types and voltage ranges.

Min Voltage

(Default: -10 volts) Configure the terminal's minimum voltage range.

Max Voltage

(Default: +10 volts) Configure the terminal's maximum voltage range.

Terminal Type

Configures the measurement mode of the selected terminal. In general, analog input channels with screw terminals use the single-ended measurement system (RSE), and analog input channels with BNC terminals use the differential (Diff) measurement system. For more information on these terminal types, refer to .

• Terminal: RSE Referenced single ended. Measurement with respect to ground (e.g. AI_GND) (Default)

• Terminal: NRSE NonReferenced single ended. Measurement with respect to single analog input (e.g. AISENSE)

• Terminal: Diff Differential. Measurement between two inputs (e.g. AI0+, AI0-)

Synchronization Configuration: eSync 2

In order to precisely synchronize the motion capture system with NI-DAQ devices, the eSync 2 must be used. This section walks through the steps on configuring the settings of the eSync 2 and the NI-DAQ in order to synchronize two systems together through the reference clock sync or the recording trigger sync.

Collecting Data

The following steps describe a general workflow on collecting signals from connected NI-DAQ channels in Motive. Make sure the camera system is before recording if you wish to collect tracking data along with the analog signals.

1. [Motive : Device pane] Open the and one of the data channels in the data acquisition device. Once it's selected, its properties will be listed out in the .

2. [Motive : Device pane] Configure NI-DAQ collection channels properties (terminal type, voltage range) as described in the section above.

3. [Motive : Device pane] Enable the channels to collect by checking the box next to each channel.

4. [Motive : Properties pane] Now, select the NI-DAQ device in the , and configure device properties (Acquisition rate, external clock).

5. [Motive : Devices pane] Make sure the NI-DAQ device enabled by checking the box next to the device.

6. [Motive : Graph View] In Live mode, scope the timeline to verify the recorded channel/terminal signals appear correctly.

7. [Motive : Control Deck] Start Recording.

Data Playback

Captured analog signals are recorded within the Take file and they can be played back in Motive. When in Edit mode, the integrated NI-DAQ device will be shown under the , and its Analog measurements can be plotted on the . You will need to create a custom graph layout and enable plotting of analog channels:

Graph Layout with Analog Plots

• Create a custom layout on the Graph View pane. → Create Layout.

• Right-click on the graph view and set the desired layout dimensions.

• On one of the graphs, right-click and under the Devices section, select the analog channels you wish to plot.

Analog Data Export

Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. You can just follow the normal the steps, and if the analog data exists in the TAK, they will also be exported.

C3D Export: Both mocap data and the analog data will be exported onto a same C3D file. Please note that all of the analog data within the exported C3D files will be logged at the same sampling frequency. If any of the devices are captured at different rates, Motive will automatically resample all of the analog devices to match the sampling rate of the fastest device. More on C3D files:

CSV Export: When exporting tracking data into CSV, additional CSV files will be exported for each of the NI-DAQ devices in a Take. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. The voltage amplitude of each analog channel will be listed. Also, mocap frame rate to device sampling ratio is included since analog data is usually sampled at higher sampling rates.

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

Troubleshooting / FAQ

Overview

Starting from Motive version 3.0 and above, the digital integration of Delsys Trigno Avanti systems is supported. Through this integration, electromyography (EMG) measurements from the Trigno Avanti EMG sensors can be recorded in Motive along with the tracking data. This page provides instructions on how to set up the Delsys Trigno Avanti platform along with the OptiTrack motion capture system.

Required Components

• Prime series Ethernet camera system

• eSync synchronization hub

• Motive 3.0 or above

• Delsys Trigno Avanti Platform with EMG sensors

• Delsys Trigger Module for synchronization

• Trigno EMGworks OR Delsys SDK server package version 3.5.8 or above.

• Firmware on both the Trigno base station and the sensors must be updated. If the firmware is installed, use the Software Update Tool to install the latest firmware. For more information, please refer to the manufacturer documentation.

Notes

• Supported Sensors: Integration is supported for Delsys Trigno EMG systems with Trigno Avanti sensors only.

• Supported Data Channels: Data channels for EMG measurements will be reported in Motive. Data channels for the inertial measurement unit (IMU) and accelerometer are not supported.

• Supported Device/Channel Count: Integration supports one Trigno base station with up to 16 EMG data channels. Additional devices and/or data channels above this limit cannot be integrated due to a restriction of the Delsys SDK.

Hardware Setup

Below are two diagrams depicting two types of Delsys hardware setups. One without a NI-DAQ device, and one with a NI-DAQ device. When setting up a configuration without a NI-DAQ device, you'll use a Delsys Trigger Module. This will only allow the option for Trigger Synchronization. If you use a NI-DAQ configuration, however, you have the option to use either Trigger and Reference Clock Synchronization. For more information about synchronization, please scroll down to the Synchronization section of this page.

Software Setup

Device Firmware

Please make sure the firmwares on both the Trigno Base Station and the EMG sensors have been updated. You can check the firmware version using the Software Update Tool provided by Delsys. For more information, please refer to the user manual.

Delsys Software Setup

Before proceeding with integrating the EMG system into Motive, please make sure the required software for the Delsys Trigno Avanti sensor system is all set up on the host computer. This includes Trigno Control Utility software which will get along with the Trigno EMGworks or Delsys SDK Server package version 3.5.8. For the sensor to work in Motive they must first be configured and paired in the Delsys Trigno Control Utility (TCU) software.

Peripheral Module Setup

In order to integrate Delsys EMG systems with Motive, you will need to setup the required drivers and plugins. Motive installer is packaged with the Peripheral Device module which can be added. During the Motive installation, a list of program features will be shown in the Custom Setup section. Here, change the setting for the Peripheral Device module, as shown in the below image, so that the module is installed along with Motive Files.

Device Setup in Motive

Step 1. Launch Delsys Trigno Control Utility software

Make sure to launch the Delsys TCU software first. Make sure all of the sensors have been powered and paired in the TCU software. If the sensors are not detected here, they will not be detected in Motive.

Step 2. Start Motive

Once the sensors are detected and running in the Delsys TCU software, launch Motive. If the peripheral module is installed, Motive will attempt to connect to the Delsys system.

Step 3. Confirm connection

In Motive: If the sensor is connected, it will be reported under the panel and the Trigno device will be listed in the .

In TCU: If the TCU software is connected to Motive, it will indicate that it has connected to a remote client. As shown in the image below.

Step 4. Enable data channels

Open the in Motive and connected Trigno device will be listed. If you click on the on the device, and all of the available data channels will be shown in the pop-up. Click on the data channels and enable the ones that will be used.

Step 5. Enable device

Once you have enabled all of the desired data channels, enable the Trigno device from the Devices pane.

Step 8. Confirm incoming data in Graph pane

As a last step, use the Graph pane to check the EMG data coming through the enabled channels.

Synchronization

Synchronization of the Delsys Trigno EMG system with the motion capture system is accomplished through triggered sync. Triggered sync, in this situation, refers to the relationship between the Delsys Trigno EMG system and the motion capture system. Meaning, the motion capture system triggers the start of data sampling of the Delsys Trigno EMG system. Once triggered, both the motion capture system and the Delsys Trigno EMG system are truly aligned only during the first frame of recording then each move forward at their own individual sampling rates in an approximation of synchronization. Reference clock synchronization is more precise, however, it is not supported by Delsys systems. This is due to a limitation of the DelsysSDK. For more information regarding Deylsys SDK, please visit their SDK page .

Triggered sync can be set up by connecting one of the eSync outputs to the Delsys Trigger Module. For triggered synchronization, one of the outputs from the eSync will need to be configured to output a signal, and it will need to be connected into the Start Input on the trigger module. The connect input port on the trigger module will also need to be set to detecting a rising edge using the toggle switch on the module.

Refer to the Delsys documentation for more information on setting up the triggered sync using the trigger module:

Setting up triggered sync

1. If not already, connect the Delsys trigger module into the Trigno base station.

2. Using a BNC cable, connect one of the output ports on the eSync into the Start Input of the triggered sync box.

3. [Motive] In Motive, select the eSync to access its properties from the .

Device Properties: Data Operation

Under Trigno device properties, you can set the following properties to perform data operations to the reported data.

Rectify Values

When enabled, all of the Raw EMG signal coming through channel 1~16 will be rectified and the absolute values of the measurements will be reported.

RMS Envelope Window

RMS is a common way to interpret EMG data. Motive performs RMS envelope calculation when reporting the data just for visualization purposes. For a complete EMG analysis, including additional data filtering for example, the Raw EMG signal should be processed through a separate data analysis software.Size of the RMS envelope can be changed by configuring the RMS Envelope Window property under Trigno device properties. This will set the number of samples used to calculate the RMS reported in Motive. Higher sample size will result in a smoother window and it needs to be adjusted based on the Trigno sampling frequency.

Noise Sample Size

Noise removal can be controlled by the Noise Sample Size property. Set this to 0 to completely disable noise removal.

Data Recording

Once Trigno system is detected in Motive and its channels are enabled, the reported EMG channel data will get recorded along with the motion tracking data. With the triggered sync setup explained above, motion capture system and the EMG system will be synchronized at the start of the recording and they will be running at their own sampling rates after the trigger point. Due to limitation of the triggered synchronization, it is recommended to keep the recordings relatively short.

The Delsys Trigno EMG device samples at a rate of 2000Hz natively, so oftentimes we are down sampling in Motive, and in rare cases, up sampling. We have found that sampling in Motive at a motion capture rate of 100Hz or 200Hz with a multiplier of 10 for the Delsys Trigno EMG device (making its sample rate at 1000Hz or 2000Hz respectively), has shown the best results. When running Motive at 120Hz, however, it has shown to have intermittent frame drops.

Data Playback

Captured analog signals are recorded within the Take file and they can be played back in Motive. When in Edit mode, the integrated EMG device will be shown under the , and its Analog measurements can be plotted on the . You will need to configure the graph layout and enable plotting of analog channels:

Graph Layout with Device Data Plots

• Create a custom layout on the Graph View pane. → Create Layout.

• Right-click on the graph view and set the desired layout dimensions.

• On one of the graphs, right-click and under the Devices section, select the analog channels you wish to plot.

Data Export

Recorded EMG channel data can be exported into C3D and CSV files along with the mocap tracking data. You can just follow the normal the steps, and if the analog data exists in the TAK, they will also be exported.

C3D Export: Both mocap data and the analog data will be exported onto a same C3D file. Please note that all of the analog data within the exported C3D files will be logged at the same sampling frequency. If any of the devices are captured at different rates, Motive will automatically resample all of the analog devices to match the sampling rate of the fastest device. More on C3D files:

CSV Export: When exporting tracking data into CSV, additional CSV files will be exported separately for each Trigno device in a Take. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. The voltage amplitude of each analog channel will be listed. Also, mocap frame rate to device sampling ratio is included since analog data is usually sampled at higher sampling rates.

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

Troubleshooting

Troubleshooting

This page provides instructions on how to integrate a Kistler force plate system with an OptiTrack motion capture system.

Overview

When a motion capture system is used in conjunction with force plates, they work together as an efficient tool for various research applications including biomechanical analysis, clinical gait analysis, physiology research, sports performance research, and many more. An OptiTrack motion capture system can synchronize with force plates to obtain both kinematic and kinetic measurements. Note that force plate integration is supported only with a Prime camera system using the eSync 2 synchronization hub. This page provides quick guidelines for setting up and configuring force plates — with digital outputs — along with the OptiTrack motion capture system.

For detailed information on specifications and configurations on the force plates, refer to the documentation provided by the force plate manufacturer.

Required Components

• Kistler Data Acquisition System

• Kistler Force Plate

• Control I/O, Sync breakout box

Hardware Setup

Component Wiring (Kistler)

Kistler Force Plate System Setup

Connect each force plate to the Data Acquisition device, and connect the USB uplink cable from the acquisition device to the host PC. For detailed instructions on setting up the Force Plate system with a host PC, refer to the Kistler documentation.

Camera System Setup

Setup the OptiTrack camera system and place the force plate(s) at the desired location(s); ideally, near the center of the volume. See or page for details.

Wiring the eSync with the Data Acquisition device

For accurate synchronizations, the must be used. The eSync 2 has signal output ports that are used to send out synchronization signals to child devices. Connect the BNC output ports of the eSync to sync input ports (Genlock/Trigger Input) of force plate amplifiers.Kistler force plates have a sync I/O breakout (Control I/O) accessory that connects to the amplifier. The eSync will connect to one of the inputs of this sync I/O box. For triggered sync, connect the output port of the eSync to the Trigger Input. For external clock sync, connect the output to the Sync Input of the sync I/O box.

Hot Plugging

Software Setup

Kistler Software Setup

Before integrating Kistler force plates into Motive, make sure all of the components required by Kistler system are set up on the computer. This includes BioWare software, the device driver (InstaCal), and other required software components. The force plate system must be recognized by Kistler's software before it can be used in Motive.

Once they are all installed, launch the BioWare software and register each force plate. During this process, you will input device information such as model number, serial number, and platform specs to configure the device setting. For more information, please refer to manufacturer documentation.

Peripheral Device Module

In order to integrate force plate systems with Motive, you will need to setup the required drivers and plugins. Motive installer is packaged with the Peripheral Device module which can be added. During the Motive installation, a list of program features will be shown in the Custom Setup section. Here, change the setting for the Peripheral Device module, as shown in the below image, so that the module is installed along with Motive Files.

For Kistler Customers

Kistler system also requires Microsoft Visual C++ 2010 Redistributable - x64 to be installed on the computer. If it is not already on the computer, you will get prompted to set this up during Motive installation process. Please make sure to have this installed as well.

Kistler Configuration Profile

After registering the force plate in BioWare, next step is to export out the device configuration XML file. In BioWare, go to the Setup → Save DataServer Configuration File to export out the configuration XML file. To add the Kistler force plates in Motive, this XML file containing the force plate information must be added to the Motive directory. Copy-and-paste the Configuration.xml file into the C:\ProgramData\OptiTrack\Motive\DeviceProfiles directory, and then rename the file to Kistler.xml. Once this is done, Motive should initialize the force plates that are detected by computer and that are registered within the XML file.

Force Plate Setup in Motive

1. Start Motive

If the hardware and software for the force plates are configured and successfully recognized, Motive will list out the detected force plates with number labels (1, 2, etc..). Motive will notify you of incorrect or nonexistent force plate calibration files. When the devices are successfully instantiated in Motive, the will indicate that the device has been created and loaded.

2. Calibrate Cameras

Calibrate the capture volume as normal to get the orientation of the cameras (see the or page for more information). The position of the force plate is about the center of the volume, and when you recalibrate or reset the ground plane, you will need to also realign the position of your force plates for best results.

3. Setup CS-400

On the , pull the force plate alignment tabs out and put the force plate leveling jigs at the bottom. The leveling jigs align the calibration square to the surface of your force plate. The alignment tabs allow you to put the CS-400 flush against the sides of your force plate giving the most accurate alignment.

4. Place CS-400 on force plate

Place the calibration wand on the force plate so that vertex of the wand is located at the right-hand corner of the side where the cable input is located (as shown in the image below). A correct placement of the calibration square is important because it determines the orientation of the force plate and its local coordinate axis within the global system. The coordinate systems for force plates are independent of the system used Motive.

5. Set force plate position in Motive.

After placing the calibration square on the force plate, select the CS-400 markers in Motive. Right click on the force plate you want to locate, and click Set Position. When there are multiple force plates in a volume, you may need to step on the force plate to find which platform the calibration square is on. In Motive, uncalibrated force plates will light up in green and a force vector will appear when you step on the plate. Repeat step 4 and 5 for other force plates as necessary.

Referencing to the markers on the calibration square, Motive defines the location of the force plate coordinate system within the global coordinate system.

Motive uses manufacturer defined X, Y, and Z mechanical-to-electrical center offset when calculating the force vector and the center of pressure. For digital based plates, this information is available from the SDK and also stored in the plate's on-board calibration data.

6. Zero force plates.

After you have calibrated each of your force plates, remove the CS-400 from the volume. Right click one of your force plates in Motive and click Zero (all). This will tare the scale and set the current force on the plate data to 0. This will account for a small constant amount of measurement offset from the force plate. Remember that it zeros all of the force plates at once. So make sure there are no objects on any of the force plates.

7. Set sampling rate

Sampling rate of force plates is configured through the synchronization setup which will be covered in the following section.

Synchronization Configuration

There are two synchronization approaches you could take: Synchronization through clock signal or through recording trigger signal.

Synchronization via clock signal utilizes the internal clock signal of the eSync to synchronize the sampling of the force plates on per-frame basis. However, when there is another device (e.g. NI-DAQ) being synchronized to the clock signal frequency, the sampling rate cannot be set for each individual device. In that case, triggered sync must be used for synchronizing the initial recording trigger. Synchronization via trigger signal utilizes the recording trigger in Motive to align the initial samples from both systems. After the initial sync, both systems run freely at their own sampling rate. If the force plates are running at whole multiples of the camera system, the collected samples will be aligned. However, since the sampling clocks are not perfectly accurate, alignment of the samples may slowly drift over time. Thus, when synchronizing via recording trigger, it is better to keep the record times short.

When synchronizing through the eSync, use the following steps to configure the sync settings in Motive. This will allow both systems to be triggered simultaneously with reference to the parent synchronization device, the eSync.

Sync Configuration Steps: eSync 2

How to Validate your Synchronization

Before you start recording, you may want to validate that the camera and force plate data are in sync. There are some tests you can do to examine this.

The first method is to record dropping a retroreflective ball/marker onto the platform few times. The bouncing ball produces a sharp transition when it hits the surface of the platform, and it makes the data more obvious for validating the synchronization. Alternately, you can attach a marker on a tip of the foot and step on and off the force plate. Make sure that your toe — closest to the marker — strikes the platform first, otherwise the data will seem off even when it is not. You can then monitor the precise timing of the ball or the foot impacting the force plate and compare them between the mocap data and the force plate data.

The following is an example of validating good synchronization outcomes:

Device Settings Profile

All of the configured device settings, including the calibration, get saved on Device Profile XML files. When you exit out of Motive, updated device profiles will be saved under the program data directory (C:\ProgramData\OptiTrack\Motive\DeviceProfiles), and this file gets loaded again when you restart Motive. You can have this file backed up to persist configured eSync 2 and device settings. Also, if you wish to reset the device settings, you can remove XML files other than the default one from the folder, and Motive will load from the default settings.

Force Plate Data in Motive

Force plate data can be monitored from the . You will need to either use a provided Force Plate Forces layout or configure a custom graph layouts to show force plate data. To view the force plate data, make sure the corresponding force plates are selected, or selection-locked, in Motive.

If you are configuring your own force plate graph layout, make sure the desired force plate data channels (Fx, Fy, Fz, Mx, My, or Mz) are selected to be plotted. Then, when you select a force plate in Motive, and the data from the corresponding channels will be plotted on the graphs. When both reconstructed markers and force plate channels are selected, the force plot will be sub-sampled in order to be plotted along with trajectory data. For more information about how to configure graph layouts, read through the page.

Live Force Plate Data

Data Export

We recommend the following programs for analyzing exported data in biomechanics applications:

C3D Export

Motive exports tracking data and force plate data into C3D files. Exported C3D files can then be imported into a biomechanics analysis and visualization software for further processing. See the or page for more information about C3D export in Motive. Note that the coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.

C3D Axes

Common Conventions

Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.

• X axis in Motive should be configured to positive X

• Y axis in Motive should be configured to negative Z

• Z axis in Motive should be configured to positive Y.

This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).

CSV Export

Force plate data and the tracking data can be exported into CSV files as well. When a Take file is exported into a CSV file. Separate CSV files will be saved for each force plate and it will contain the force, moment, and center of pressure data. Exported CSV file can be imported for analysis.

Data Streaming

To stream tracking data along with the force plate data, open the Data Streaming Pane and check the Broadcast Frame Data, and make sure that you are not streaming over the camera network. Read more about streaming from the workflow page.

Motive can stream the tracking data and the force plate data into various applications — including Matlab — using protocol. Find more about from the User's Guide included in the download.