Hello All,
I have used OpenSim for a while but I am still in the process of learning, so I hope I can get some help to solve my problem. I apologize if it is something easily solvable, but it is something I am have been thinking of for a while, I hope some external opinion can somehow help me!
I am working on the upper limb model to run some dynamic simulation during wrist movements. I am now using the MoBL_ARMS model on OpenSim 3.3, which includes the hand, for forearm, the upper arm and the thorax segments. The task I am studying is executed with the subject seated with the upper arm in a relaxed position, the forearm in horizontal position on a support (e.g. table) and the wrist outside the support free to move.
What is the best and/or easiest way to model the fact that the forearm is supported externally, so that elbow flexors don't have to activate to sustain it? Would be the application on each of the bodies in the forearm of a force equal and opposite to the gravity force an option?
Thank you for your help!
Enrico
Modeling of an external frame sustaining part of the model
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Enrico Piovanelli
- Posts: 5
- Joined: Wed Aug 31, 2016 5:45 am
Re: Modeling of an external frame sustaining part of the model
Hi Enrico,
Would a simple solution like locking the elbow joint (restraining any movement of this joint) be appropriate? Or does the elbow flex during the movement above the table? If this were the case you could also clamp the elbow joint to a specific range thus not allowing it to extend past 90 degrees?
Aaron
Would a simple solution like locking the elbow joint (restraining any movement of this joint) be appropriate? Or does the elbow flex during the movement above the table? If this were the case you could also clamp the elbow joint to a specific range thus not allowing it to extend past 90 degrees?
Aaron
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Enrico Piovanelli
- Posts: 5
- Joined: Wed Aug 31, 2016 5:45 am
Re: Modeling of an external frame sustaining part of the model
Hi Aaron,
thank you very much for the reply!
Actually the forearm is not supposed to be moving on the support. In fact we are considering whether fixing the forearm on the support with some straps might be necessary or not.
I tried to lock the elbow flexion Coordinate on a simple wrist flexion simulation and I checked the effect with the inverse dynamics. However the elbow moment with the elbow locked is the same as the elbow moment without the elbow joint locked, so I guess locking the coordinate is something that influence the kinematics but not the dynamics..I haven't tried clamping the elbow coordinate with a short range as you suggested, but given the results with the elbow Coordinate locked I feel like it will not effect the dynamics as well..
Enrico
thank you very much for the reply!
Actually the forearm is not supposed to be moving on the support. In fact we are considering whether fixing the forearm on the support with some straps might be necessary or not.
I tried to lock the elbow flexion Coordinate on a simple wrist flexion simulation and I checked the effect with the inverse dynamics. However the elbow moment with the elbow locked is the same as the elbow moment without the elbow joint locked, so I guess locking the coordinate is something that influence the kinematics but not the dynamics..I haven't tried clamping the elbow coordinate with a short range as you suggested, but given the results with the elbow Coordinate locked I feel like it will not effect the dynamics as well..
Enrico