Parameters & Commands

We will use the <odrv> as a placeholder for any ODrive object. Every ODrive controller is an ODrive object. In odrivetool and the Web GUI this is usually odrv0. Furthermore we use <axis> as a placeholder for any axis, which is an attribute of an ODrive object (for example odrv0.axis0). An axis represents where the motors are connected.

Per-Axis Commands

For the most part, both axes on the ODrive can be controlled independently.

State Machine

The current state of an axis is indicated by <axis>.current_state. The user can request a new state by assigning a new value to <axis>.requested_state. The default state after startup is AxisState.IDLE. A description of all states can be found here.

Startup Procedure

By default the ODrive takes no action at startup and goes to idle immediately. In order to change what startup procedures are used, set the startup procedures you want to True. The ODrive will sequence all enabled startup actions selected in the order shown below.

• <axis>.config.startup_motor_calibration

• <axis>.config.startup_encoder_index_search

• <axis>.config.startup_encoder_offset_calibration

• <axis>.config.startup_closed_loop_control

See here for a description of each state.

Control Mode

The default control mode is position control. ControlMode.POSITION_CONTROL If you want a different mode, you can change <axis>.controller.config.control_mode. Possible values are listed here.

Control Commands

• <axis>.controller.input_pos = <turn>

• <axis>.controller.input_vel = <turn/s>

• <axis>.controller.input_torque = <torque in Nm>

Modes can be selected by changing <axis>.controller.config.input_mode. The default input mode is InputMode.PASSTHROUGH. Possible values are listed here.

System Monitoring Commands

Encoder Position and Velocity

• View the position with <axis>.pos_vel_mapper.pos_rel [turns] or <axis>.pos_vel_mapper.pos_abs [counts]

• View rotational velocity with <axis>.pos_vel_mapper.vel [turn/s]

Motor Current and Torque Estimation

• View the commanded motor current with <axis>.foc.Iq_setpoint [A]

• View the measured motor current with <axis>.foc.Iq_measured [A].

Noisy Iq_measured

If you find that this returns noisy data then use the command motor current instead. The two values should be close so long as you are not approaching the maximum achievable rotational velocity of your motor for a given supply voltage, in which case the commanded current may become larger than the measured current.

Using the motor current and the known KV of your motor you can estimate the motors torque using the following relationship:

Torque [N.m] = 8.27 * Current [A] / KV

General System Commands

Saving the Configuration

All variables that are part of a [...].config object can be saved to non-volatile memory on the ODrive so they persist after you remove power. The relevant commands are:

• <odrv>.save_configuration(): Stores the configuration to persistent memory on the ODrive.

• <odrv>.erase_configuration() Resets the configuration variables to their factory defaults. This also reboots the device.

Diagnostics

• <odrv>.serial_number: A number that uniquely identifies your device. When printed in upper case hexadecimal (hex(<odrv>.serial_number).upper()), this is identical to the serial number indicated by the USB descriptor.

• <odrv>.fw_version_major, <odrv>.fw_version_minor, <odrv>.fw_version_revision: The firmware version that is currently running.

• <odrv>.hw_version_major, <odrv>.hw_version_minor, <odrv>.hw_version_revision: The hardware version of your ODrive.

Setting up Sensorless

The ODrive can run without encoder/hall feedback, but there is a minimum speed, usually around a few hundred RPM. In other words, sensorless mode does not support stopping or changing direction!

Sensorless mode starts by ramping up the motor speed in open loop control and then switches to closed loop control automatically. The sensorless speed ramping parameters are in <axis>.config.sensorless_ramp. The sensorless_ramp.vel and sensorless_ramp.accel (in [radians/s] and [radians/s^2]) parameters control the speed that the ramp tries to reach and how quickly it gets there. When the ramp reaches sensorless_ramp.vel, <axis>.controller.input_vel is automatically set to the same velocity, in [turns/s], and the state switches to closed loop control.

If your motor comes to a stop after the ramp, try incrementally raising the sensorless_ramp.vel parameter. The goal is to be above the minimum speed necessary for sensorless position and speed feedback to converge - this is not well-parameterized per motor. The parameters suggested below work for the D5065 motor, with 270KV and 7 pole pairs. If your motor grinds and skips during the ramp, lower the sensorless_ramp.accel parameter until it is tolerable.

Below are some suggested starting parameters that you can use for the ODrive D5065 motor. Motor calibration and setup must also be completed before sensorless mode will work.

<axis>.controller.config.vel_gain = 0.01
<axis>.controller.config.vel_integrator_gain = 0.05
<axis>.controller.config.control_mode = ControlMode.VELOCITY_CONTROL
<axis>.controller.config.vel_limit = <a value greater than <axis>.config.sensorless_ramp.vel / (2pi * <pole_pairs>)>
<axis>.config.motor.current_soft_max = 2 * <axis>.config.sensorless_ramp.current
<axis>.config.load_encoder = EncoderId.SENSORLESS_ESTIMATOR
<axis>.config.commutation_encoder = EncoderId.SENSORLESS_ESTIMATOR

To start the motor, set <axis>.requested_state to AxisState.CLOSED_LOOP_CONTROL