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Allow higher order spline derivatives. #176

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Allow higher order spline derivatives. #176

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Allow higher order spline derivatives.
myeatman-bdai Nov 20, 2025
ec8b67b
Merge branch 'master' into spline-derivatives
myeatman-bdai Nov 20, 2025
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10 changes: 5 additions & 5 deletions spatialmath/spline.py
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Original file line number Diff line number Diff line change
Expand Up @@ -133,12 +133,12 @@ def __call__(self, t: float) -> SE3:
"""
return SE3.Rt(t=self.spline_xyz(t), R=self.spline_so3(t).as_matrix())

def derivative(self, t: float) -> Twist3:
linear_vel = self.spline_xyz.derivative()(t)
angular_vel = self.spline_so3(
t, 1
def derivative(self, t: float, order: int = 1) -> Twist3:

@bokorn-bdaii bokorn-bdaii Nov 20, 2025 •
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Add some warning that this only works for order = [1,2]. Current system throws a value error for order != [0,1,2] but will fail on order 0 with a "ValueError: bad value to Twist constructor" error. We should check and throw errors for order != [1,2].

@myeatman-bdai myeatman-bdai Nov 21, 2025

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Thanks for testing that

linear = self.spline_xyz.derivative(order)(t)
angular = self.spline_so3(
t, order
) # 1 is angular rate, 2 is angular acceleration
return Twist3(linear_vel, angular_vel)
return Twist3(linear, angular)

@petercorke petercorke Aug 20, 2026

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Careful with semantics —Twist3 represents finite displacement (pose logarithm) rather than instantaneous velocity. Passing (v,ω) directly makes methods like .exp() implicitly bake in Δt=1 s. We should scale by dt or use a dedicated velocity class/structure.

This will work but the usage doesn't match with the documentation for the class. Perhaps need a VelocityTwist3 class.

Are you simply looking for a container to hold (v,ω) like a ROS Twist message?



class SplineFit:
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