Standalone ODrive ROS2 node

This packages serves as a standalone ROS2 node to control the ODrive via CAN.

For information about installation, prerequisites and getting started, check out the ODrive ROS CAN Package Guide.

Interface

Parameters

• node_id: The node_id of the device this node will attach to
• interface: the network interface name for the can bus
• axis_idle_on_shutdown: Whether to set ODrive to IDLE state when the node is terminated

Subscribes to

• /control_message: Input setpoints for the ODrive.

  The ODrive will interpret the values of input_pos, input_vel and input_torque depending on the control mode.

  For example: In velocity control mode (2) input_pos is ignored, and input_torque is used as a feedforward term.

  Note: When changing input_mode or control_mode, it is advised to set the ODrive to IDLE before doing so. Changing these values during CLOSED_LOOP_CONTROL is not advised.

Publishes

• /odrive_status: Provides ODrive/system level status updates.

  For this topic to work, the ODrive must be configured with the following cyclic messages enabled:

  • error_msg_rate_ms
  • temperature_msg_rate_ms
  • bus_voltage_msg_rate_ms

  The ROS node will wait until one of each of these CAN messages has arrived before it emits a message on the odrive_status topic. Therefore, the largest period set here will dictate the period of the ROS2 message as well.

• /controller_status: Provides Controller level status updates.

  For this topic to work, the ODrive must be configured with the following cyclic messages enabled:

  • heartbeat_msg_rate_ms
  • encoder_msg_rate_ms
  • iq_msg_rate_ms
  • torques_msg_rate_ms

  The ROS node will wait until one of each of these CAN messages has arrived before it emits a message on the controller_status topic. Therefore, the largest period set here will dictate the period of the ROS2 message as well.

Services

• /request_axis_state: Sets the axes requested state.

  This service requires regular heartbeat messages from the ODrive to determine the procedure result and will block until the procedure completes, with a minimum call time of 1 second.

  If the requested state is anything other than IDLE, this sends a clear_errors request to the ODrive (see below) before sending the state request.

• /clear_errors: Manual service call to clear disarm_reason and procedure_result, reset the LED color and re-arm the brake resistor if applicable. See also clear_errors().

  This does not affect the axis state.

  If the axis dropped into IDLE because of an error and the intent is to re-enable it, call /request_axis_state instead with CLOSED_LOOP_CONTROL, which clears errors automatically.

Data Types

All of the Message/Service fields are directly related to their corresponding CAN message. For more detailed information about each type, and how to interpet the data, please refer to the ODrive CAN protocol documentation.

Enum types and their corresponding integer values are listed in the ODrive API reference:

• AxisState
• ControlMode
• InputMode

If you have the odrive Python package installed (not mandatory for this ROS node), you translate enums like this:

from odrive.enums import AxisState
print(AxisState.CLOSED_LOOP_CONTROL) # 8
print(AxisState(8).name) # CLOSED_LOOP_CONTROL