eliabntt/custom_6dof_joint_controller

Control a 6 joint robot (free floating) with six separate PID with ROS in simulation.

CUSTOM ROS PID CONTROLLER for a FREELY MOVING ROBOT (6DOF)

The main branch focuses on position setpoints, the irotate_edits branch focuses on velocity setpoints.

The irotate_edits branch will be soon merged into the main branch. You can easily fork this repo and address your own changes. With the irotate_edits you can see also see how the project can be used for multiple robots at the same time.

This repository is part of the GRADE project

The peculiarity of this controller is that it commands a robot in ROS Simulations by directly giving JOINT VELOCITY COMMANDS.

The controller is completely customizable. You can change the set of joints or add some. Check the example in the irotate_edits branch where we control x-y-yaw-camera_yaw-wheel[0,1,2]-joints.

The robot will be moved directly by the joints!

This controller is useful whenever you cannot control the robot as usual, like omnidirectional robots that need to move perpendicularly to the wheels or in not-fluidodynamics simulation [drones, submarines] or in any other case.

You can associate a PID controller to each JOINT or set the velocities directly.

You can define for each joint: limits (both position and velocity), PID+Anti windup configs.

You can either listen to a JointState topic to get the current state or you can subscribe to an odometry topic.

The main differences between the two branches are as follow:

• iRotate listen for two odometries and use sinchronized messages
• iRotate works with (local) velocity setpoints rather than global position ones
• iRotate shows how to control joints directly without the embedded PID controller (set speed instead of target).

Main branch

joint_names: ["x_joint", "y_joint", "z_joint", "roll_joint", "pitch_joint", "yaw_joint"]

The publish rate is 100Hz.

Installation

Simply download and build, you just need standard ros packages.

Launch and config

You can launch the node with

roslaunch custom_joint_controller_ros

The main params are

<param name="odom" value="/$(arg namespace)/odom" />
<param name="setpoint" value="/$(arg namespace)/full_predicted_state" />
<param name="joint_command" value="/$(arg namespace)/joint_commands" />

namespace is the name of the robot.

The config.yaml file contains the other settable parameters.

The setpoint is a full predicted state from a NMPC in my case. I then take the last point of the trajectory and set it as the goal of the PID. You can easily change that piece of code.

For reference I use the nmpc in rotors_simulator (here) to compute the trajectory.

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CITATION

If you find this work useful please cite our work as

@misc{https://doi.org/10.48550/arxiv.2303.04466,
  doi = {10.48550/ARXIV.2303.04466},
  url = {https://arxiv.org/abs/2303.04466},
  author = {Bonetto, Elia and Xu, Chenghao and Ahmad, Aamir},
  keywords = {Robotics (cs.RO), FOS: Computer and information sciences, FOS: Computer and information sciences},
  title = {GRADE: Generating Realistic Animated Dynamic Environments for Robotics Research},
  publisher = {arXiv},
  year = {2023},
  copyright = {arXiv.org perpetual, non-exclusive license}
}