Issue: Inverse Dynamics with Recursive Newton-Euler Not Working for URDF Imports #486
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Inverse dynamics with recursive Newton-Euler does not work for URDF imports and also not for the Panda model: import roboticstoolbox as rtb robot = rtb.models.Panda() q = np.random.rand(robot.n) qD = np.random.rand(robot.n) qDD = np.random.rand(robot.n) tau = robot.rne(q, qD, qDD) The origin of the error is jp = self.links[j].parent.jindex which is empty for some types. I implemented a another search algorithm of the parent algorithm via: jp = next(i for i, link in enumerate(self.links) if link.name == parent_name)
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Problem:
The inverse dynamics computation using the recursive Newton-Euler algorithm (rne) does not work for URDF imports and also fails for the provided Panda model:
Cause of the Error:
The issue originates from the line:
jp = self.links[j].parent.jindexFor certain types, parent.jindex is empty, causing the computation to fail.
Proposed Solution
Solution:
I implemented an alternative method to find the parent index using the following approach:
jp = next(i for i, link in enumerate(self.links) if link.name == parent_name)Additional information
Roboticstoolbox version: 1.1.1
Numpy version: 1.26.4
Spatialmath version: 1.1.14