03/21/21 - SW/FW Standards

03/21/21

Notes

• Position
  • SW always sends absolute position in radians
  • Joint ranges (TODO: figure these out for all the joints)
    • Turntable
      • -90 to +90 (0 is the middle)
    • Shoulder linear actuator
      • 0 to max + value
    • Elbow
      • TBD
    • Wrist
      • 0 = parallel to forearm (for pitch and roll)
  • URDF determines default positions + directions (cw / ccw)
    • Backburner: move this somewhere shared between sw/fw
  • All absolute encoders track joint position
  • Continuous motion joints (range is -inf to + inf)
    • Wrist roll
    • Gimbal pan
      • Backburner: report continuous position (eg. >360 degree positions)
    • Want to be able to move x many rotations
• Velocity
  • SW sends velocity in rad/s
  • Directions follow position directions
• Current
  • Amps
• Force
  • Newtons
• Need to calibrate relative encoders to determine range
  • Do not allow these commands until calibration complete
  • Have calibrate commands (don't calibrate on startup)
  • Wrist calibration sequence
    • Rotate until middle limit switch is triggered (is either 0 position or some known offset) (roll)
    • Run both motors at same speed until top limit is reached (pitch)
    • Run both motors at same speed until bottom limit is reached (pitch)
• Differential control (wrist)
  • SW sends motor commands
• Everything else
  • SW sends joint commands
• Reset command
  • PID
    • Doesn't reset gains, resets accumulator
  • Encoders
    • Relative
      • Reset count to 0
    • Absolute
      • Don't reset position to 0
• TODO
  • Keep FW in joint space for now, but
  • We should eventually move everything to motor space (no more joint space)
    • FW needs to convert between motor and joint (sensors live here) space
  • Get ranges of motion from mech