Further tuning of "VelocityControl" feature in drive software #4
Description
Before the Granite State District (GSD) event, we changed the drive software in SpeedRacerDrive() to use closed-loop velocity control, rather than open-loop PercentVbus control. We have had excellent success with closed-loop velocity control in some prior years (e.g. 2015 and 2016) but didn't use it in 2018 or 2019 for reasons that I don't recall. (Maybe not enough time for tuning? Little perceived benefit for those drivetrains?) In any case, we found it very helpful for this year in 2020, particularly for low-speed robot control. However, it is really not quite properly tuned, particularly for low-speed arcing turns, resulting in a fair bit of "stuttering drive" particularly on the inside wheel of turns. This "stuttering drive" is hard on the gearboxes and mechanism and may be reducible through tweaking various TalonFX parameters for the velocity PIDF control, including not just PIDF parameters, but ramp rates and similar parameters. Further tuning of these would benefit from some focused time on the issue, potentially including the use of PhoenixTuner (which we haven't used much for PIDF tuning in the past) to give us better visibility into what is going on and more data on how to properly fix the problem.