Static Optimiaztion & Forward Dynamics

[Alessandro Pirelli]

Hi everyone,

I'm trying to develop and exosuit to assist in movements of the arm. Basically, starting from a muscoloskeletal model, I added some cables which will be used to move the joints and perform the desired movement. Part of this process is to optimize the design of the device in order to have to use the minimum possible tension to perform the movements.

I have tried to use the Static Optimization tool, studying a model which featured only the cables (and no muscles) that were in the best position (analyzing the force files generated from the tool itself to identify the design which had the minimum maximum value for the cable) and using trajectoryies defined by MATLAB, but the results I got are rather strange. Anyways, I tried to use the controls file generated by the Static Optimization tool to run the Forward Dynamics tool, to make sure that those controls actually led to the movement that I was trying to replicate, but unsurpisingly it wasn't the case, and instead I got a completely wrong movement.

If anyone has any suggestion, that would really appreciated since I've been stuck on this matter for days and don't get what's wrong.

Thank you in advance

[Carmichael Ong]

Static Optimization does not yield controls that will generate a forward dynamics simulation since it analyzes each time step independently and does not include tendon dynamics.

Some other workflows that could be useful are Computed Muscle Control and Direct Collocation (which we provide some tools in OpenSim Moco). You can get an overview of these and other workflows at our Documentation site: https://simtk-confluence.stanford.edu/d ... +Workflows