Misalignment of robot joint and human joint

#1

Hi, My name is Alan.
I just started learning to use AnyBody software.
I currently have an elbow exoskeleton (1-DoF) model for elbow flexion/extension. I create a human model with trunk and right arm. The pelvis is fixed. Also, the other joint of right arm is fixed. Only fe joint is free to rotation. I want to obtain the force of the elbow joint when the human elbow joints and robot joint are misalignments. I mean the rotation axis of both robot-human joints are misalignment (maybe 2 or 3 mm). Is it possible to simulate this situation? Could you please help me how to do it step by step? Or is it possible to apply a torque on the point near the elbow joint about 2mm?

Thank you very much.

#2

Hi Alan,

Yes it is possible to simulate this

Using the overdetermined solver you will need to make soft kinematic constraints between the exo and the human this will allow the exo/arm exo to move even though the alignment is not perfect, and in this way it will not lock. Alternatively you can use Forcedependent kinematics to do the same but this is more advanced and will require knowledge of stiffness between human and exo.

Please see this tutorial on overdetermined kinematics. https://anyscript.org/tutorials/Making_things_move/lesson2.html

Best regards
Sørem