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.

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.

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.