PCS (Piecewise Constant Strain) Systems¶

This section covers continuum soft robots modeled using the Piecewise Constant Strain (PCS) approach based on discrete Cosserat rod theory.

Overview¶

PCS systems model continuum soft robots by dividing them into segments, each with constant strain. This approach provides:

• Accurate continuum modeling with manageable complexity
• Support for both 2D (planar) and 3D (spatial) robots
• Various actuation methods (tendons, pressure chambers)
• Efficient numerical implementation using Gauss-Legendre quadrature

Available Systems¶

Base Implementations¶

Spatial PCS¶

Core 3D PCS implementation for spatial continuum robots.

• 6 strain components per segment: [kappa_x, kappa_y, kappa_z, sigma_x, sigma_y, sigma_z]
• SE(3) kinematics with 4x4 transformation matrices
• Foundation for 3D specialized variants

Planar PCS¶

2D PCS continuum soft robots.

• 3 strain components per segment: [kappa_z, sigma_x, sigma_y]
• SE(2) kinematics with [theta, x, y] pose representation
• Suitable for real-time applications

Composable actuation¶

PCS and PlanarPCS accept actuator models through actuators=. Tendons, pushing rods, simplified muscles, and equivalent pressure chambers use the shared threadlike actuation model. Passive routed mechanics are installed separately with ThreadlikeImpedance.

Pneumatic actuation¶

I-Support¶

3D pneumatic soft robot with specific chamber configuration.

• 3 chambers per segment
• Specialized for the I-Support robot platform

When to Use¶

References¶

The PCS model is based on:

Renda, F., Boyer, F., Dias, J., & Seneviratne, L. (2018). Discrete cosserat approach for multisection soft manipulator dynamics. IEEE Transactions on Robotics, 34(6), 1518-1533.