Expand on discussion of Units in SysId

[DeltaDizzy]

The unit dropdown is only for labeling the gains, and units should align with the units that the sensor/controller in the robot code uses.

[thenetworkgrinch]

Example that would generate only relevant Feedforward but invalid Feedback constants

SysIdRoutine

private final SysIdRoutine      m_sysIdRoutine   =
      new SysIdRoutine(
          // Empty config defaults to 1 volt/second ramp rate and 7 volt step voltage.
          new SysIdRoutine.Config(Volts.per(Second).of(ElevatorConstants.kElevatorRampRate),
                                  Volts.of(9),
                                  Seconds.of(10)),
          new SysIdRoutine.Mechanism(
              // Tell SysId how to plumb the driving voltage to the motor(s).
              m_motor::setVoltage,
              // Tell SysId how to record a frame of data for each motor on the mechanism being
              // characterized.
              log -> {
                // Record a frame for the shooter motor.
                log.motor("elevator")
                   .voltage(
                       m_appliedVoltage.mut_replace(
                           m_motor.getAppliedOutput() * RobotController.getBatteryVoltage(), Volts))
                   .linearPosition(m_distance.mut_replace(getHeight()))
                   .linearVelocity(m_velocity.mut_replace(getVelocity()));
              },
              this));
// getHeight() returns Meters
// getVelocity() returns Meters Per Minute

Controller setpoint for Spark

m_controller.setReference(Elevator.convertDistanceToSensorUnits(Meters.of(goal)).in(Rotations), // Problem here
                              ControlType.kMAXMotionPositionControl,
                              ClosedLoopSlot.kSlot0,
                              m_feedforward.calculate(getVelocity().in(Meters.per(Minute))));
// getVelocity() returns the MetersPerMinute