PID Testing

Click on image for high quality version.

Don, Dave Cramb, Ryan, and David were out on Monday testing the boat and latest GUI code. We were able to send instructions to the boat to take a target heading and then graph the response of the boat.  The y-axis (delta) is the difference between the current heading and the target heading. The GUI could graph the response in real time, allowing us to get instant feedback on the performance of the boat. It was good to have Ryan there as he has more experience tuning PID loops and was able to offer some tips.

We experimented changing the PID values and the rudder limit to try and make the response quicker and reduce overshoot. Unfortunately the wind died down during the middle of our test session so we weren’t able to complete testing. We did learn that removing the rudder limit lead to unpredictable responses, and settled on a a limit of 15-20 as suitable. We also have determined that we likely don’t need the D (derivative) term in the PID loop and that a PI controller will likely suffice.  We will experiment with different values of P and I on friday if the weather cooperates.
All in all, the boat is performing very well already, and tuning the PID is going to perfect the responsiveness of the steering.

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