CTU-CRAS-NORLAB Hexapod controller

This package provides a simple versatille open-loop controller for quasi-static multi-legged robots. It is the accompanying controller for the DARPA Subterranean Challenge Virtual Model Submission of ctu_cras_norlab_lily robot.

Requirements

• Ubuntu 18.04
• ROS melodic

Features

• Allows omnidirectional locomotion
• Configurable for different platform designs with differing morphology, including up to eight legs each with 3 degrees of freedom.
• User defined body clearance and step clearance

Configuration

The robot parameters are configured using the json configuration file. For information on parameters see readme.md in the config directory.

Usage

The controller is automatically started together with the Ignition Gazebo simulation of the ctu_cras_norlab_lily hexapod robot.

The controller processes the robot json configuration file during the initialization and automatically sets the body clearance, step clearance, and maximum step length that defines the maximum velocity. Afterwards, the robot is stearable using the standard /cmd_vel velocity command of type geometry_msgs/Twist, for example:

rostopic pub /cmd_vel geometry_msgs/Twist "linear:
  x: 0.5
  y: 0.5
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.0"

Note that the vehicle moves with a constant maximum forward and angular velocity. This is a design choice and cannot be changed. Therefore the input twist command is used for weighting the maximum step length, and therefore the valid values are in range [-1,1].

Additionaly, the user may control the body clearance and step clearance by publishing appropriate masseges on the /body_clearance and /step_clearance topics. The controller accepts clearance larger than 0 as std_msgs/Float64 messages.

Publications

If you use this work in an academic context, please cite the following publication.

@article{faigl19ras,
  title = {Adaptive Locomotion Control of Hexapod Walking Robot for Traversing Rough Terrains with Position Feedback Only},
  author = {Faigl, Jan and Čížek, Petr},
  journal = {Robotics and Autonomous Systems},
  volume = {116},
  pages = {136--147},
  year = {2019},
  doi = {10.1016/j.robot.2019.03.008},
  video = {https://youtu.be/Tdzt4yDQWI0}
}

Faigl, J. and Čížek, P.: Adaptive Locomotion Control of Hexapod Walking Robot for Traversing Rough Terrains with Position Feedback Only, Robotics and Autonomous Systems, 116, 136-147, 2019.

Licence

The software included in this package is released under a Apache License 2.0 license.