How do I configure force plates for analog capture in Nexus?

To configure force plates for analog data capture:

1. In the System resources pane, click the Go Live button.

The first time you use Nexus, the Devices node is empty. You must add and configure a new force plate device before it will be displayed in the System resources tree.

2. In the System resources tree, right-click the Devices node, point to Add Analog Device and select from the following options for force plates:

Add AMTI AccuGait Force Plate

Add AMTI OR6 Series Force Plate

Add Bertec Force Plate

Add Kistler Force Plate (External Amplifier)

Add Kistler Force Plate (Internal Amplifier)

Add Motekforce Link 2x6D Instrumented Treadmill

The selected force plate node automatically expands to display the newly created device. If the appropriate type is not displayed, contact Vicon Support.

The colored icon beside a force plate node identifies the status of the device and of any connected analog source:

Green play button: Component OK (active or connected); if an analog device is connected, the analog source is selected and all channels are configured.

Yellow pause button: Component is not fully set up (e.g., not all channels have been assigned a pin or the calibration matrix has not been configured).

Gray play button: Component connected but not contributing any data.

Red stop button: Component down (unavailable or disconnected).

These colored icons correspond to those used for the device summary in the Status communications pane.

3. In the Properties section at the bottom of the System resources pane, view or change settings for the following properties:

a. In the General section, enter a Name.

b. In the General section, load the manufacturer's calibration file:

i. If the calibration file is not listed in the drop-down list, click the Browse for a folder button, browse to the location of the calibration file and select it. The file becomes available in the drop-down list.

ii. Select the calibration file.

If not supplied by the manufacturer's calibration file, you can set the device Dimensions, Position, Orientation, and Origin in those Properties sections.

c. If there is no calibration file, click Show Advanced at the top right of the Properties section and enter the Calibration Matrix 6x6 Matrix values manually.

* The Matrix values must be entered, either via a calibration file or by manual entry, in order for the force plate to become active.

d. In the Source section, select a Source (the Lock+ to which the device is attached) from the drop-down list. For legacy hardware you will select the Giganet MX.

For force plates attached to a Lock+ with an analog card, the Source drop-down list contains all connected Locks; a USB force plate will have its Source drop-down list populated with connected USB devices of the required type.

e. In the Source section, use the Fill button to populate the input connections sequentially (if these are consecutive on the Lock+).

f. In the Source section, select the Gain for the Source from the choice of gains available for the Lock+.

* Click Show Advanced at the top right of the Properties pane to see additional settings that may be available for the selected device. To show basic settings only, click Hide Advanced.

4. In the System resources tree, if necessary, expand the force plate node to expose the Force, Moment and CoP (Center of Pressure) channels.

The colored icon beside the device output node identifies the analog channel status:

Green arrow: Analog channel connected to source device.

Yellow yield: Analog channel has not been assigned a pin.

5. To tare the force plate at zero load:

In the General section, click the Zero Level browse button and enter the matrix properties.

You can also tare the force plate by right-clicking on the force plate name in the System resources tree and selecting Zero Level.

6. In a 3D Perspective view pane, ensure that a gray or colored rectangle with the number 1 on it, representing the force plate, is displayed in the capture volume where you have positioned it.

If you have multiple force plates configured, they will be numbered in the order they appear in the System resources tree.

7. In the capture volume, have someone step onto the force plate. You should see the force vector display in real time.

8. At the top of the System resources pane, press the Save button to save your system configuration settings to a .System file in the Systems configurations folder (by default Nexus 1.x, C:\ProgramData\Vicon\Nexus\Configurations\Systems by default Nexus 2.x, C:\Users\Public\Documents\Vicon\Nexus2.x\Configurations\Systems ).

9. From the System resources tree, expand the force plate node and select the Force output.

10. Switch to a Graph View pane.

If necessary, select Components from the Graph Type drop-down list. A real-time graph of the Force output is displayed.

11. Verify that the vertical (Fz) force component is equal to [known mass * 9.81].

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