novaphy.spatial_cross_motion¶
Featherstone spatial cross product motion-on-motion: returns the 6×6
matrix v × such that v × w accelerates a spatial motion vector w by
v in the same frame. Convention: 6D motion vectors are stored as
[angular(3); linear(3)].
Parameters¶
| Parameter | Description |
|---|---|
v |
Spatial motion vector, shape (6,). Layout [ωx, ωy, ωz, vx, vy, vz]. |
Returns¶
A (6, 6) matrix M such that the time derivative of a moving spatial
motion vector w (under the velocity v) is M @ w.
Example¶
import numpy as np
import novaphy
v = np.array([0, 0, 1, 0, 0, 0], dtype=np.float32) # spin about z
M = novaphy.spatial_cross_motion(v)
print(M.shape) # (6, 6)
Notes¶
- Used internally by forward_link_velocities to propagate joint velocities along an articulation.
- The companion form for spatial forces (wrenches) is spatial_cross_force.