novaphy.spatial_cross_force¶
Featherstone spatial cross product motion-on-force: returns the 6×6
matrix v ×* such that v ×* f is the rate of change of the spatial
force f due to motion v in the same frame. Convention: 6D force
vectors are stored as [torque(3); force(3)], paired with the
[angular; linear] motion convention.
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
force f (under the velocity v) is M @ f.
Example¶
import numpy as np
import novaphy
v = np.array([0, 0, 1, 1, 0, 0], dtype=np.float32)
M_force = novaphy.spatial_cross_force(v)
print(M_force.shape) # (6, 6)
Notes¶
- Used internally by inverse_dynamics to propagate force-style derivatives along an articulation.
- For motion-style derivatives use spatial_cross_motion.