odrive_can_ros_drive

Overview

ROS driver for the ODrive motor controller connecting through CAN bus

This is a basic driver node for ROS which builds an interface to control multiple ODrive motor controllers through a CAN bus. This driver depends on socketcan_bridge package to connect to physical CAN bus.

Right now driver only supports velocity control mode as this was my prime area of interest for my own project but it can be extended to provide support for other modes of control. I would be happy to accept any pull requests extending funtionality of this driver.

This driver was successfully tested with multiple ODrive controllers on a CAN bus connected to Raspberry Pi 4 through Waveshare CAN hat on Ubuntu 18.04 and 20.04 with ROS melodic and noetic.

Usage

Getting the code

To use the driver just check it out to your ROS workspace:

git clone https://github.com/belovictor/odrive_can_ros_driver.git

Dependancies

The driver depends on socketcan_bridge package. Please install it prior to using the driver:

sudo apt install ros-<ros distribution name>-socketcan-bridge

The package name would depend on your ROS version. This driver has been tested and is known to work with melodic and noetic.

Configuration

Driver is configured with the following configuration paramters:

Parameter name	Type	Description
can_device	String	CAN device name as it appears on ifconfig interface list, default is can0
can_rx_topic	String	Topic name through which driver receives CAN messages from socketcan_bridge
can_tx_ropic	String	Topic name through which driver sends CAN messages to socketcan_bridge
update_rate	Double	Update rate in Hz of how frequently driver gets data from ODrive controllers
engage_on_startup	Boolean	If driver should engage all motors on startup (not implemented yet)
axis_min_velocity	Double	Minimum axis velocity, if target velocity is less then this value then it is set to this value (if set to 1.0 target velocity of 0.5 will become 1.0, target velocity of -0.5 will become -1.0)
axis_names	String[]	Array of names of axises which are then used to name topics corresponding to axises
axis_can_ids	Int[]	Array of axis CAN ids as they are configured on ODrive controllers for every axis
axis_directions	String[]	Axis direction either forward or backward, backward reverses axis control, angle and current velocity

An example configuration is presented in config/odrive.yaml.

Running the driver

roslaunch odrive_can_ros_driver odrive_can_ros.launch

How it works?

On the high level this driver has very simple architecture. On one hand it interacts with CAN bus through 2 topics (one for receiving CAN frames and one for transmitting them) provided by socketcan_bridge node. On the other hand it provides several topics for every ODrive axis defined in the configuration for other nodes like controllers and hardware interfaces to interact with. The example configuration file provided with the driver shows how to connect to a 6WD chasis based on 3 ODrive controller boards. The axises are addressed through CAN bus according to their axis IDs configured on ODrive controller through <odrv>.<axis>.config.can.node_id attribute

When driver is started it creates the following topics for every axis configured:

Topic name	Message type	Direction	Description
<axis name>/angle	std_msgs/Float64	Outbound	Angle of the axis in rad
<axis name>/current	std_msgs/Float64	Outbound	Axis current consumption
<axis name>/current_velocity	std_msgs/Float64	Outbound	Current axis angular velocity in rad/s
<axis name>/output_velocity	std_msgs/Float64	Outbound	Velocity which is sent to ODrive (will differ from target_velocity if axis_min_velocity is set)
<axis name>/target_velocity	std_msgs/Float64	Inbound	Target axis angular velocity in rad/s
<axis name>/voltage	std_msgs/Float64	Outbound	Axis voltage of power supply in V

So basically you can control every axis by setting the target velocity and monitor axis activity/performance through current angle and velocity and also monitor power supply and consumption through voltage and current.