Kubo: VCU and HCU Wiring - olinrobotics/gravl GitHub Wiki

VCU: receives position commands from the Hindbrain on Serial port S1. It controls the following:

M# Actuator Type Sensor Type Control Surface
M1 DC Motor 10K Potentiometer Velocity Pedal
M2 DC Motor 10K Potentiometer Steering Wheel

HCU: receies position commands from the Hindbrain on Serial port S1. It controls the following:

M# Actuator Type Sensor Type Control Surface
M1 Linear Actuator Internal Potentiometer Hitch Pitch Lever (Coming Soon!)
M2 Linear Actuator Internal Potentiometer Hitch Height Lever

2. Preparation

  1. Check that stall current of motors can be handled by RoboClaw
  • Peak current (per channel) of 2X45 RoboClaw: 60A
  1. Wire 12V source to +/- on the main screw terminal
  • DOUBLE-CHECK THIS, OTHERWISE YOU KILL THE ROBOCLAW
  • MAKE SURE YOUR POWER SUPPLY CAN SOURCE OPERATING CURRENT! A lead-acid battery is a good choice.

4. HCU

4.0 Hardware

  • 2X30 RoboClaw Motor Controller (reference)
  • 6in Stroke Length Linear Actuator (reference)

4.1 General Settings

  • Stall current of velocity actuator:
  • Stall current of steering actuator: 44.4A

3. VCU

3.0. Hardware

For specific information on these parts, please see the Kubo hardware documentation. (documentation)

  • 2X45 RoboClaw Motor Controller (reference)
  • DC Motor
  • Velocity Pedal 10k Potentiometer (from You-Do-It)
  • Steering Actuator
  • Steering 10k Potentiometer (from You-Do-It)

3.1. Get Pot Limits

Determine the Roboclaw readings for the max and min positions of the potentiometer. This step is important because if the potentiometer is pushed past these readings for any reason, it will be permanently ruined.

  1. Remove potentiometer from mount, but keep it wired to the Roboclaw.
  2. Spin potentiometer clockwise with gentle pressure until it stops. Record the M# encoder value in Motion Studio software.
  3. Repeat for the counter-clockwise direction.
  4. Repeat for the other potentiometers

3.1. General Settings

Insert image of general settings here
Setup appropriate values for the "General Settings" page. See the boxed values in the image above for the important values to check.

  • Control Mode: Set Roboclaw mode for external control. Use Packet Serial to allow the Teensy to communicate over a serial connection.
  • C
    • Stall current of hitch actuator: 5A

Setup and Tuning of Potentiometers

  1. Choose resistors for potentiometers in actuators (see p. 81 of RoboClaw User Manual) (link)
  • 10K Velocity Potentiometer: In-line resistor value 15K
  • 10K Steering Potentiometer: In-line resistor value 15K
  • 10K Hitch Potentiometer: In-line resistor value 15K
  1. Solder resistors in-line with 5VDC POT line (see next step for identification tables)

Device Status Page

General Settings page

Velocity Settings page

Position Settings page

Misc Notes

  • Potentiometers are susceptible to noise, deadzone in RoboClaw changes measurement sensitivity
  • Full potentiometer range in the RoboClaw is 0 to ~1750, we further limit the range in firmware to prevent breaking it. If you get readings outside that range, the potentiometer is probably broken
  • Current values that we use for the potentiometer can be found in the hindbrain.h file
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