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This information is for Vicon Nexus 2.14. For up-to-date help, see the latest Nexus documentation.

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You can configure monitors in a variety of ways.

For examples of configuring monitors, see the following:

Configure multiple actions on one monitor

A single monitor can perform multiple actions, such as to write a time bar event, display a progress bar, and sound a tone.

To configure a monitor with multiple actions that detects only the first occurrence of an event:

  1. Configure a monitor to detect an event.
  2. Add a Timebar Event action.
  3. Add a Toggle Monitor action to toggle the monitor Off so that the Timebar Event is identified only the first time.

Configure multiple monitors

You can use multiple monitors to identify multiple events. Each event type, such as Foot Strike and Foot Off, would have its own monitor.

For example, you may want one monitor to look for the start of a particular body motion, which starts another monitor that evaluates whether the pelvic alignment is within the threshold range. If the pelvic alignment exceeds the threshold range, the second monitor could sound a tone to notify the operator, and activate a third monitor to evaluate the range of yet another element.

To configure multiple monitors:

  1. Configure monitor 1 to detect the counter-motion of a jump (e.g., when the angular velocity of the knee exceeds a threshold).
  2. Add a Capture action to the monitor to start a capture when this condition is met.
  3. Add a Toggle Monitor action to toggle the monitor off so that the capture is initiated only once.
  4. Configure monitor 2 to detect the maximum height of the sacrum for both the initial jump and the jump after landing on the force plate (Maximum Value on Exit).
    Add a Timebar Event action to the monitor.
  5. Configure monitor 3 to detect landing on the force plate.
    Set the Threshold Mode to monitor the vertical force value (Fz) at the appropriate threshold (On Enter).

    Force plate monitor properties will depend on which force plate device is being used. Some force plates used with Vicon Nexus register a positive vertical force on contact (such as the AMTI), while others register a negative force on contact (such as Kistler).
  6. Add a Timebar Event action.
  7. Configure monitor 4 to detect takeoff from the force plate.
    Set the Threshold Mode to detect when the vertical force value (Fz) drops below a threshold (you can use the same trigger value as for Monitor 3, but you would set the condition to On Exit).

Configure multiple actions on multiple monitors

To configure multiple monitors, each with multiple actions:

  1. Configure a primary monitor to trigger the detection of trial events (e.g., subject jumps onto a force plate and then jumps off).
  2. Configure a series of monitors with Timebar Event actions (e.g., Foot Strike and Foot Off).
  3. Clear each monitor's check box so that its initial state is Off.
  4. Add a Toggle Monitor action to the primary monitor for each event monitor.
  5. Set each Toggle Monitor to On. Once the primary monitor is triggered, the event monitors will turn On. The events are detected and written to the time bar.
The trial conditions could be such that a primary monitor isn't necessary to control the event detection monitors in Step 2. The value of the primary monitor is to make sure that the monitored parameters are in the proper state for appropriate event detections. This is a safeguard against identifying false events.

Configure Boolean monitors

You should carefully consider how you configure Boolean monitor thresholds and triggers to execute event actions.

If you use an AND monitor, it will mark an event only if the conditions of the child monitors occur at the same frame (an AND monitor event requires all child monitor parameters to be true). This seems obvious, but let's say you want to mark an event when parameter 1 is above one threshold and parameter 2 falls below another threshold. You'd be inclined to set:

  • AND Child monitor 1:
    • Threshold Mode: Above Upper
    • Condition: On Enter
  • AND Child monitor 2:
    • Threshold Mode: Below Lower
    • Condition: On Enter

However, configured this way, the AND monitor will mark the event only if the two parameters enter the respective threshold regions on the same frame, which is unlikely.

Unless you want this specific occurrence tracked, instead you would set:

  • AND Child monitor 1:
    • Threshold Mode: Between
    • Condition: Within
  • AND Child monitor 2:
    • Threshold Mode: Below Lower
    • Condition: On Enter

Configured in this way, when the parameter for Child monitor 1 is within its threshold, the action will execute the instant the parameter for Child monitor 2 falls below its threshold.

If you use an OR monitor, because the child monitor trigger conditions do not need to coincide (an OR monitor requires only one of the monitor parameters to be true), you can set:

  • OR Child Monitor 1
    • Threshold: Above Upper
    • Trigger: On Enter
  • OR Child Monitor 2
    • Threshold: Below Lower
    • Trigger: On Enter