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jhu-cisst / cisst

JHU ERC CISST Library
http://github.com/jhu-cisst/cisst/wiki
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fix an inverse kinematics bug #60

Open ChengzhiSONG6 opened 6 years ago

ChengzhiSONG6 commented 6 years ago

transform translation error to spatial frame

simonleonard commented 6 years ago

Why is the translation error not in the spatial frame to start with?

ChengzhiSONG6 commented 6 years ago 
        The translation error is in the spatial frame, it’s the Js column here is the screw axis description, which is not the same as velocity mapping for joint velocity to end effector velocity.

https://groups.google.com/forum/#!topic/research-kit-for-davinci/srs_NPBw-fU

simonleonard commented 6 years ago

I cannot answer the question (whether you are right or not) if you do not give the kinematic chain of the robot.

Otherwise it is very possible that a robot's first joint results in 0 spatial linear velocity in a given configuration.