pathfinder

This checkpoint is basically a repeat of last week's. We have to follow the figure-eight track in the lab, or the more elaborate track in the courtyard, preceded by a 1-ft drop test.

I've modified the firmware a bit to provide more proportional control (r43). Turns out we were not appropriately scaling down the value for the steering angle, and so it would always snap full left or full right. I also reduced the "lost" threshold quite a bit (from 3000 down to 1000), to allow better use of the proportional steering. It's still terribly non-linear, and we'll have to do something about that.

Currently it drives fairly smoothly along straights, and curves well in one direction, but not so well in the other. This is due, I think, to the input from the left & right sensors being so different.

The firmware behaves a bit differently now, too. Upon reset, it's not in tracking mode. This means that the steering servo won't change, even though the steering computation is being done. To enter tracking mode, press Enter (the joystick button). The green LED should light up. To exit tracking mode, center the wheels, and stop the motor, press the Cancel.

When the car gets into "lost" mode, it will steadily light either the red LED or yellow LED, indicating steering to the right or left, respectively.

To conduct today's checkpoint, press Enter to enter tracking mode, place the car on the track to ensure steering, then speed up the motor. Pushing the joystick forward increases the speed, rearward decreases it. Three or four clicks should be sufficient, although I had it up to five or six in testing. Make sure the E-Stop is disengaged.

The car doesn't handle step responses well. It steps well to the left, but occasionally misses a step to the right. However, it enters a loop the the left, and picks up the track after 360° (this is on the lab track).