Add closed-loop support for elevator

first95 / FRC2018

The code base for our 2018 robot

MIT License

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Add closed-loop support for elevator #37

Closed jwalthour closed 6 years ago

jwalthour commented 6 years ago

[x] Add encoders to hardware
[x] Determine safety precautions to take -- in practice and in code -- during tests with motors
[x] Incorporate encoder feedback to have closed-loop distance and speed control
[x] Add homing switch support
[x] Add soft limits

jwalthour commented 6 years ago

As of 7a1fe4c15383e2d37a63ad690ccbeefc93f0dd79, controlling the velocity via position control mode works. The winch movement is a bit jittery - we still need to do some tuning.

jwalthour commented 6 years ago

An early draft of safety rules:

Only turn on the robot with the elevator at the bottom of its travel (for homing correctly)
- If you turn on the robot without the elevator at the bottom of its travel, put the elevator at the bottom, then restart the robot code
- Don't enable until you've done that
Before enabling, make sure:
- Fingers are clear of the elevator slide mechanism
- The collector won't smack someone when it rises
- Fingers are clear of the elevator winch
- Shoelaces and hair are clear of the winch
- Shoelaces and hair are clear of the collector chains

jwalthour commented 6 years ago

Additional safety rule:

Whenever changing control code, test it out with a second person ready with their finger on the disable switch. (A second person can react faster, and they should be paying full attention) Do not stop using a second person until everything has worked smoothly at least once, preferably several times. Changes to control code include:
- Any change to PID constants
- Changes to homing logic
- Changes to operator interface, such as:
  - Moving control to a different button or joystick
  - Changing sensitivity
- Trying a new auto move

jwalthour commented 6 years ago

Reworked control system in 568cbab8568767f7547032ecd59b331965ee3131. Now A, B, X, Y are preprogrammed setpoints, the right stick is throttle control, and when all of those are released, the position is held.

jwalthour commented 6 years ago

Homing switch : 8401566a11f42438dd1ed6346a24fdfcff026311 Soft limits: c6f59e9498e0bff8d1061dd2ea6fc631ec9cdb58 Safety procedure: above, probably oughta write them up someplace and discuss them with the students.