mini-cheetah-motor-driver-socketcan 0.2.2

A Python Driver for MIT Mini-Cheetah Actuator which uses SocketCAN for communication.

Python Motor Driver for Mini Cheetah Actuator: T-Motor AK80-6

Dependencies:

• bitstring

Install via:

pip3 install bitstring

Documentation

• Useful videos:
  • From T-Motor
  • From Skyentific
• Datasheet
• Ben Katz Documentation

Pre-requisites:

• Setting up the CAN interface:

  • Run this command and make sure that can0 (or any other can interface depending on the system)shows up as an interface after connecting the USB cable to your laptop: ip link show

  • Configure the can0 interface to have a 1 Mbaud communication frequency: sudo ip link set can0 type can bitrate 1000000

  • To bring up the can0 interface, run: sudo ip link set up can0

• To change motor parameters such as CAN ID or to calibrate the encoder, a serial connection is used. The serial terminal GUI used on linux for this purpose is cutecom

Usage:

Import: from motor_driver.canmotorlib import CanMotorController

Example Motor Initialization: motor = CanMotorController(can_socket='can0', motor_id=0x01, motor_type='AK80_6_V2', socket_timeout=0.5)

Available Functions:

• enable_motor()
• disable_motor()
• set_zero_position()
• send_deg_command(position_in_degrees, velocity_in_degrees, Kp, Kd, tau_ff):
• send_rad_command(position_in_radians, velocity_in_radians, Kp, Kd, tau_ff):
• change_motor_constants(P_MIN_NEW, P_MAX_NEW, V_MIN_NEW, V_MAX_NEW, KP_MIN_NEW, KP_MAX_NEW, KD_MIN_NEW, KD_MAX_NEW, T_MIN_NEW, T_MAX_NEW)

All motor communication functions return current position, velocity, torque in SI units except for send_deg_command. change_motor_constants does not return anything.

Supported Motor Configurations:

• AK80-6 (From Cubemars, Firmware versions v1 and v2): motor_type='AK80_6_V1' and motor_type='AK80_6_V2'
• AK80-9 (From Cubemars, Firmware version v2): motor_type='AK80_9_V2'

# Working parameters for AK80-6 V1.0 firmware
AK80_6_V1_PARAMS = {
                "P_MIN" : -95.5,
                "P_MAX" : 95.5,
                "V_MIN" : -45.0,
                "V_MAX" : 45.0,
                "KP_MIN" : 0.0,
                "KP_MAX" : 500,
                "KD_MIN" : 0.0,
                "KD_MAX" : 5.0,
                "T_MIN" : -18.0,
                "T_MAX" : 18.0,
                "AXIS_DIRECTION" : -1
                }

# Working parameters for AK80-6 V2.0 firmware
AK80_6_V2_PARAMS = {
                "P_MIN" : -12.5,
                "P_MAX" : 12.5,
                "V_MIN" : -38.2,
                "V_MAX" : 38.2,
                "KP_MIN" : 0.0,
                "KP_MAX" : 500.0,
                "KD_MIN" : 0.0,
                "KD_MAX" : 5.0,
                "T_MIN" : -12.0,
                "T_MAX" : 12.0,
                "AXIS_DIRECTION" : 1
                }

# Working parameters for AK80-9 V2.0 firmware
AK80_9_V2_PARAMS = {
                    "P_MIN" : -12.5,
                    "P_MAX" : 12.5,
                    "V_MIN" : -25.64,
                    "V_MAX" : 25.64,
                    "KP_MIN" : 0.0,
                    "KP_MAX" : 500.0,
                    "KD_MIN" : 0.0,
                    "KD_MAX" : 5.0,
                    "T_MIN" : -18.0,
                    "T_MAX" : 18.0,
                    "AXIS_DIRECTION" : 1
                    }

To add a new constants configuration use the change_motor_constants function or create an issue with the constants and motor information on the GitHub page to be added to the driver.