MATLAB Answers

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How to accurately model a single human leg in SimScape?

Asked by Hüseyin Eken on 18 Jul 2018
Latest activity Answered by Steve Miller on 2 Apr 2019
Hello all! I am working on a school project about an assistive lower limb exoskeleton. But before I must model a single human leg in SimScape for a realistic approach. I have modeled the human leg as a double pendulum in SolidWorks and converted into Simulink environment via SimScape Multibody Link. I am applying Computed-Torque control and have designed a PID Controller. The system follows the trajectory that I am feeding (joint angles from a database) all is good so far. But the generated torques does not match with the human joint torques evaluated by numerous industries during gait analysis.
I am guessing it is because of GRFs. I have the GRF values and tried applying them as a force to the Simscape Model and calculated their torques and add to the controller (even in various combinations). No luck :(
I am asking what should I do to model my system more like a real human leg and/or fit my torque values to given human joint moments as it can be?

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1 Answer

Answer by Steve Miller on 2 Apr 2019

Hi - I am no expert in modeling human limbs. I can only guess at some of the effects your model may be missing.
  1. Simulated torques seem quite low. Are you neglecting friction in the joints?
  2. GRF - I assume this is ground reaction force. Are you sure you are applying them in the correct reference frame?
If you are looking for an example, this one shows the process of moving from a desired trajectory to joint torques. It, however, neglects GRF until the final stage.
Good luck!
--Steve

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