Servo Stickyness in Tracking


This following code is used to limit the Y servo in the Tracking service.  Previously the first line did not exist an the PID value would be computed even if the servo limit did not allow it to move.  This would make a "very" sticky problem because the computed PID value would grow and grow and if the target was in a valid range - it would take the same amount of time (or greater) to get unstuck as the time it was stuck.

Now, however, the PID value is not computed when the servo has hit a limit (a good thing) - 
The servo is not given the opportunity to move (bad thing)

It should move but only back to a valid position - it should not move or compute PID value for a position which would put it "more" into the invalid range

So logic will be needed to see if the new possible position is in the valid region - then it should be allowed to compute PID and move - otherwise write the error.

if ((currentYServoPos <= ymin && ySetpoint - targetPoint.y < 0) || (currentYServoPos >= ymax && ySetpoint - targetPoint.y > 0)) {
				error(String.format("%d y limit out of range", currentYServoPos));
			} else {
				if (ypid.compute()) {
					computeY = ypid.getOutput();
					currentYServoPos += (int) computeY;
					if (currentYServoPos != lastYServoPos) {
						currentYServoPos = y.getPosition();
						lastYServoPos = currentYServoPos;
				} else {
					log.warn("y data under-run");

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GroG's picture

No Stickyness Problem

I tested and after observing where my limits are, I don't believe Ale's script nor the Tracking service have a "sticky" problem.  

Some things which threw me off are :

  • I did not know where my limits were (eyes have very narrow limits) - so that added to my confusion
  • I was expecting movement after I hit a limit and then moved the point in the other direction - THIS IS NOT AND SHOULD NOT BE THE CASE 

    Say the X min limit has been reached in the above picture (min is to the right), the X servo will be frozen until it crosses the middle of the screen, and goes to the LEFT side - after the point crosses the center the x tracking will resume.  This is how it is expected to work, although its not necessarily intuitive when the point gets "close" to the center but still there is no movement (IT MUST BE LEFT OF CENTER FOR TRACKING)