Motor Control
The motor controllers are connected to the Raspberry Pi 4 (4GB RAM), which has Ubuntu 20.04 installed. The motor controllers are controlled using the ROS2 Foxy framework (note not Humble distro!), which is already installed on the Pi.
Usage
In the first terminal, run:
cd Phoenix-Linux-SocketCAN-Example
sudo ./canableStart.sh # start the CANable interface
cd ../motor_control_ws
source install/setup.bash
ros2 launch ros_phoenix trunk.launch.py
cd motor_control_ws
source install/setup.bash
ros2 run converter converter_node # optionally add --ros-args -p debug:=true
Motor control modes
The motor control modes are as follows:
| Mode | Value |
|---|---|
PERCENT_OUTPUT |
0 |
POSITION |
1 |
VELOCITY |
2 |
CURRENT |
3 |
FOLLOWER |
5 |
MOTION_PROFILE |
6 |
MOTION_MAGIC |
7 |
MOTION_PROFILE_ARC |
10 |
To simply run a command once to test the motor control, the following command can be used:
ros2 topic pub --once /all_motors_control interfaces/msg/AllMotorsControl "{motors_control: [{mode: 0, value: 0.25},{mode: 0, value: 0},{mode: 0, value: 0},{mode: 0, value: 0},{mode: 0, value: 0},{mode: 0, value: 0}]}"
Motor control limits
The motor control limits are empirically established as follows:
\[
\operatorname{norm}\left(0.75\left(\vec{u}_3+\vec{u}_4\right)+1.0\left(\vec{u}_2+\vec{u}_5\right)+1.25\left(\vec{u}_1+\vec{u}_6\right)\right) \leq 0.6
\]
Going beyond this limit can result in the robot going outside of the workspace, which can be dangerous.