Jaguars and FAST PID Looptimes

[Joe Johnson]

First off, I am back. This time I'm working with Overclocked, #246.

Second, you'll all be shocked SHOCKED our Fall Practice Project* is a swerve drive chassis**

Third, since we want to this chassis to go the direction we want it to go and we don't want to be waiting around for the steering error to settle down to an acceptable level, we are going to put as much power as we dare into the steering angle drive . Bottom line, we are using a Banebot RS775-18 on each wheel (and there are 4 of course, 4 wheel independent steer swerve -- how could we do less?). So... we get the torque we need and still have the speed we want.

BUT... speed has a dark side. Speed is hard to control, especially at 50hz update rates typically used in FIRST control loops (I want to have 90 degree step change in steering angle in under 60ms -- probably too fast to have a 20ms loop time). I hear good things about the not yet available Talon SRX (coming soon to a FIRST Legal robot near you) but hearing good things doesn't help me today if it isn't available. So, we are left with Jaguars.

Now comes my question:
Has anyone had good luck using the Jaguar's in their PID mode with high speed actuators and very fast loop times? If so, please let me know in the comments below. I want to know the good the bad and the ugly.

Also, Jaguars are also unavailable for sale these days. Anyone willing to sell (or loan) me 4? If so, PM me with details.


Stay tuned for more results and videos as the project progresses.

Joe J.


*Yes, Fall Practice Projects are a thing. If your team is not doing one or more of them, you should be.

**Super Thanks go to Anthony Lapp and his company, Team221 Robotics, for helping us out with Wild Swerves. Literally wouldn't have been able to do this practice project without building off a solid swerve design.