GVS Systems (Geometric Variable Strain)¶
This section covers continuum soft robots modeled with the Geometric Variable Strain (GVS) approach.
GVS uses the shared continuum link, cross-section, isotropic material, and joint model described in Continuum Robot Components. See Parameters, Updates, and Optimization for construction, replacement, and identification workflows.
Overview¶
GVS systems generalize PCS by allowing arbitrary strain basis functions instead of piecewise constant assumptions. A model is assembled from GVSSegment entries, where each segment contains a LinkSpec, JointSpec, StrainBasisSpec, and num_gauss_points.
Public Specs¶
| Spec | Purpose |
|---|---|
GVSSegment |
Complete declaration of one GVS segment |
LinkSpec |
Link geometry, material properties, and length |
JointSpec |
Preceding joint type and optional joint parameters |
StrainBasisSpec |
Strain basis family, active components, and orders |
Basis Functions¶
| Name | Description |
|---|---|
monomial |
Polynomial basis functions |
legendre |
Legendre polynomial basis |
chebyshev |
Chebyshev polynomial basis |
fourier |
Fourier series basis |
gaussian |
Gaussian radial basis functions |
imq |
Inverse multiquadric basis |
Joint Types¶
| Name | DOF | Description |
|---|---|---|
fixed |
0 | Rigidly connected |
revolute |
1 | Single rotation axis |
prismatic |
1 | Single translation axis |
helical |
1 | Coupled rotation and translation |
cylindrical |
2 | Rotation plus translation along one axis |
planar |
3 | Planar motion |
spherical |
3 | Three-axis rotation |
free |
6 | Fully free spatial joint |
Available Systems¶
GVS¶
Core 3D GVS implementation for generalized continuum robots.
GVS accepts the same composable actuators= interface as PCS. Routed tendons,
pushing rods, muscles, and equivalent chambers are described in the
threadlike actuation guide.
GVS vs PCS
Use PCS when piecewise constant strain is sufficient. Use GVS when you need flexible basis functions, segment-specific joints, or hybrid soft-rigid parametrizations.