A ROS node providing a driver interface to the Roboclaw motor controller.
There are several existing ROS nodes for the roboclaw, including:
- https://github.com/sonyccd/roboclaw_ros
- https://github.com/doisyg/roboclaw_ros
- https://github.com/SV-ROS/roboclaw_driver
All three follow a similar approach, where the Roboclaw node is essentially the 2-wheel differential drive base (aka base_link). Therefore, the Roboclaw node in these repositories compute and publish the Odometry and tf frame data.
However I am buidling a 4-wheel differential drive base that drives two Roboclaw controllers. I have a separate base node that sends commands to two separate Roboclaw driver nodes. Therefore this roboclaw driver node needed to be more of a ROS wrapper to the Roboclaw controller.
In my robot, the Odometry and tf frames will be computed and published by the separate base node, using encoder readings published by the Roboclaw nodes as well as fused with IMU sensor data to improve the Odometry accuracy.
~dev_name- Serial (aka USB) device name~baud- Default 115200~address- Serial address, default 0x80~loop_hz- Number of publisher loops per second (Hertz)~deadman_secs- Seconds until motors stop without additional commands~test_mode- True = run the Roboclaw simulator stub for testing~speed_cmd_topic- Topic on which to listen for SpeedCommand messages~stats_topic- Topic on which Stats messages will be published
Stats topic: <node_name>/stats
- Motor 1 & 2 encoder values
- Motor 1 & 2 speed values in QPPS (+/-)
Diagnostic updater topic: /diagnostics
- Temperature 1 (C)
- Temperature 2 (C)
- Main Battery (V)
- Logic Battery (V)
- Motor 1 current (Amps)
- Motor 2 current (Amps)
SpeedCommand topic: base_node/speed_command
- M1 and M2 motor speed in QPPS
- Max seconds before automatically stopping
Clone the repository
cd $ROS_WORKSPACE/src
git clone https://github.com/sheaffej/roboclaw_driver.git
Build the package to create the message bindings
cd $ROS_WORKSPACE
catkin_make
Launch the node
roslaunch roboclaw_driver roboclaw_node
Unit and node-level tests are performed by catkin_make run_tests. These are also automatically run by the Travi-CI config.
The script tests/run_tests.sh is a helper script to manually run the unit tests using pytest and the node-level tests using rostest. I like to run the helper script before committing changes to the repo, then Travis-CI runs them again as part of the automated build testing.
The only logic that is non-trivial and therefore likely to break during refactoring is the RoboclawStub object that simulates the hardware controller for use in testing. The rest of the logic is more of a wrapper, and therefore will be tested during node-level integration testing.
pytest src/test_roboclaw_stub_unit.py
Launches a test node to control the roboclaw_driver node using the simulated roboclaw controller (RoboclawStub)
rostest roboclaw_driver stub.launch
The roboclaw.py library is every so slightly modified (basic formatting and comments) from the version downloadable from the Ion Motion control site :
http://downloads.ionmc.com/code/roboclaw_python.zip
The Travis-CI configuration uses ROS Industrial's industrial_ci: https://github.com/ros-industrial/industrial_ci