/ros2-pneumatic_actuation

ROS2 packages for pneumatic actuation with pressure regulators

Primary LanguagePython

ROS2 Pneumatic Actuation

ROS2 package for the pneumatic actuation of continuum soft robot arms.

Usage

Build

colcon build --packages-select pneumatic_actuation_demos

Run pressure trajectory node

ros2 run pneumatic_actuation_demos pressure_trajectory_node

Run with launch file

ros2 launch pneumatic_actuation_demos default.launch.py

Conventions

Chambers

We are using a chamber numbering convention analogue to the parametrized lengths L_i referred to in [1]. This means that for a four chamber segment:

  1. Chamber 1: points along the positive local x-axis
  2. Chamber 2: points along the negative local x-axis, e.g. opposite of chamber 2.
  3. Chamber 3: points along the positive local y-axis
  4. Chamber 4: points along the negative local y-axis, e.g. opposite of chamber 3.
  5. The positive z-axis is in a right-handed coordinate system to the x- and y-axis and points along the distal end of the robotic arm.

Chamber numbering convention used in this repository for the four-chamber per segment case. The figure is adapted from [1].

Pressure torque

We define pressure torques as wrenches produced by perpendicular forces acting on the tip plane of the segment at the Center of Pressure (CoP), which is displaced at a distance of r_p from the center-line representing the lever arm of the torque. For a four chamber segment, we remind ourselves of the following convention:

  1. When we apply a positive pressure torque in x-direction, the robot should be bending with a positive angle around the x-axis. This means, that we have to increase the pressure in chamber 3 and decrease the pressure in chamber 4. The robot will have negative local y-position coordinates.
  2. When we apply a positive pressure torque in y-direction, the robot should be bending with a positive angle around the y-axis. This means, that we have to increase the pressure in chamber 2 and decrease the pressure in chamber 1. The robot will have positive local x-position coordinates.

Convention for pressure torques acting on the segment. n represents the x-axis and e the y-axis.

Citations

[1] Della Santina, C., Bicchi, A., & Rus, D. (2019, November). Dynamic control of soft robots with internal constraints in the presence of obstacles. In 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) (pp. 6622-6629). IEEE.