I am trying to get distance travelled along the Y axis by integrating the Y acceleration from the IMU. I am using the blocks shown below. But when I invoke this procedure the distance is always 0 and I get the message “Incorrect block plugged into the position socket of the block labelled “Position Y”.Expected Position”. But the block I used (highlited) says it is a position object. So what is the problem?
You are trying to extract the Y field twice. Only need to extract it once, from a Position object.
Plug the highlighted Block directly into PositionVariable or plug PositionVariable directly into Telemetry.
This allows the OpMode to function as you intended, showing Telemetry of a non-zero Y position that updates with the loop interval.
As you will see, the Y positions change (very fast) with IMU drift and double-integration.
Cosmetic improvements could include:
- start the integration thread before loop, not inside the loop
- experiment with Poll Interval vs. loop cycle time
- round the Telemetry to zero decimals
- specify the units
- specify a starting Y position of zero
- stop the integration thread when done
But these will not address the fundamental issue of gyro drift with double-integration. FTC teams use other ways to determine distance traveled.
Side note: this post uses the legacy BNO055 IMU and its associated Blocks. The current universal IMU interface is described here at ftc-docs.
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