Balancing robot

Parts list

• ODrive / ODESC / ...
• Two hoverboard motors
• Arduino Mega
• Arduino Nano
• NRF24L01
• MPU6050
• Arduino Uno + joystick + NRF24L01 (remote)
• Battery
• Frame

ODrive / ODESC / ... settings

If you have not worked with ODrive / ODESC / ... before, I recommend following my getting started guide.

The following settings are based on the ODrive hoverboard guide.

The hoverboard motors have 15 polepairs.

odrv0.axis0.motor.config.pole_pairs = 15

odrv0.axis1.motor.config.pole_pairs = 15

Because the motors have a high resistance, you need to increase the calibration voltage.

odrv0.axis0.motor.config.resistance_calib_max_voltage = 4

odrv0.axis1.motor.config.resistance_calib_max_voltage = 4

Lower the current range to get a better reading.

odrv0.axis0.motor.config.requested_current_range = 25

odrv0.axis1.motor.config.requested_current_range = 25

Lower the bandwidth to get better control.

odrv0.axis0.motor.config.current_control_bandwidth = 100

odrv0.axis1.motor.config.current_control_bandwidth = 100

Enter the estimated torque constant.

odrv0.axis0.motor.config.torque_constant = 8.27 / 16

odrv0.axis1.motor.config.torque_constant = 8.27 / 16

The hoverboard motors use hall effect sensors.

odrv0.axis0.encoder.config.mode = ENCODER_MODE_HALL

odrv0.axis1.encoder.config.mode = ENCODER_MODE_HALL

The hall effect sensors in combination with the magnets produce 90 counts per revolution.

odrv0.axis0.encoder.config.cpr = 90

odrv0.axis1.encoder.config.cpr = 90

To get better alignment, use 150 pulses for the calibration.

odrv0.axis0.encoder.config.calib_scan_distance = 150

odrv0.axis1.encoder.config.calib_scan_distance = 150

odrv0.axis0.encoder.config.bandwidth = 100

odrv0.axis1.encoder.config.bandwidth = 100

Set the controller gains.

odrv0.axis0.controller.config.pos_gain = 1

odrv0.axis1.controller.config.pos_gain = 1

odrv0.axis0.controller.config.vel_gain = 0.02 * odrv0.axis0.motor.config.torque_constant * odrv0.axis0.encoder.config.cpr

odrv0.axis1.controller.config.vel_gain = 0.02 * odrv0.axis1.motor.config.torque_constant * odrv0.axis1.encoder.config.cpr

odrv0.axis0.controller.config.vel_integrator_gain = 0.1 * odrv0.axis0.motor.config.torque_constant * odrv0.axis0.encoder.config.cpr

odrv0.axis1.controller.config.vel_integrator_gain = 0.1 * odrv0.axis1.motor.config.torque_constant * odrv0.axis1.encoder.config.cpr

Set the velocity limit.

odrv0.axis0.controller.config.vel_limit = 10

odrv0.axis1.controller.config.vel_limit = 10

Set the control mode to velocity.

odrv0.axis0.controller.config.control_mode = CONTROL_MODE_VELOCITY_CONTROL

odrv0.axis1.controller.config.control_mode = CONTROL_MODE_VELOCITY_CONTROL

If you are using the latest firmware version.

odrv0.config.enable_brake_resistor = True

After changing settings, use save and reboot.

odrv0.save_configuration()

odrv0.reboot()

Programming

This project is based on these two James Bruton projects.

The remote uses the same code as James' remote but the pins are not the same and it only uses one joystick.

It's the same remote as my cable cam project, based on this video.

There is a small mistake in the schematic, make sure to use the written pin numbers because pin 13 is not correct in the schematic.

There is code for the remote (Arduino Uno), the main controller (Arduino Mega) and the Arduino that handles the accelerometer (Arduino Nano), you can download the code here.

There is also a calibration file in the folder, you need to run that on the Arduino Nano, replace the values in the imu-code and upload it.

Wiring diagram

For this project I used a dual axis ODESC.

This is the schematic for the balancing robot.

It is recommended to use 22 nanofarad capacitors between the hall effect sensor lines and ground, on the ODESC these are on the board so they are not needed.