rrr-arm VS ros_controllers

Here is a simple robot arm built with primitive geometry and interfaced with Gazebo. A teaching assistant from Worcester Polytechnic Institute informed me it is beneficial. He used it with a robotics course.

I recommend starting with the CAD model of the manipulator and then using it to generate the URDF (there is a plugin for that). This will enable you to visualize and simulate it in Gazebo and make the motion planning with moveit. I even started from before that and built a simple RRR arm from scratch here. I made it without CAD, but the reason was that I wanted to understand the internals. I used moveit here for planning with collision avoidance. There are steps to generate moveit config package for your robot in the same link.

Either use this node, or take a good look at it and make a variant if it needs changes. https://github.com/ros-controls/ros_controllers/blob/noetic-devel/diff_drive_controller/src/diff_drive_controller.cpp

Here's the code and the equations are found on line 491 and 492.

You can check this repo for inspiration https://github.com/ros-controls/ros_controllers/tree/noetic-devel/ackermann_steering_controller as it implements odometry for robots with Ackermann steering. But it doesn't translate angular velocity into steering angle (I'm working on it in my own project).