how to set up CMC
Posted: Thu May 20, 2021 5:35 am
Hello everyone!
I am working on the development of a Full Body Model for the simulation of human walking with an exoskeleton and crutches. My aim is to perform dynamic simulations too using GRFs acquisitions.
What I would like to do would be to use Computed Muscle Control (CMC) in order to calculate the excitation of muscles given a certain trajectory.
What I have at the moment is the trajectory and GRFs.
My issue is that I do not really understand how I should structure the Residual_Actuators and the Tasks files.
- Residual Actuators: are they compulsory? I do not understand why muscles on their own should not be able to produce enough force for a walking movement. In case I have to add them, do I have to add a reserve actuator to each joint that is moving during the given trajectory?
- Tasks: it is the file indicated which coordinates have to be tracked. Do I have to include all the coordinates that change their value during the given trajectory? Or just some of them?
And about the weight: is it ok if I use weight = 1 for each coordinate or should I use a different value, higher/lower for some of them? IN case, how can I choose this value?
In the simulations I am running at the momento the main problems are that:
- OpenSim crutches saying that the model is not able to develop the required accelerations: do you know why it happens?
- In the simulations that reach an end the resulting movement is completely uncorrected with the model wriggling on himself.
Can anyone help me with these issues. I looked a lot on the internet too but I could not find specific information and guidelines about how to do CMC.
Thank you!
Francesca
I am working on the development of a Full Body Model for the simulation of human walking with an exoskeleton and crutches. My aim is to perform dynamic simulations too using GRFs acquisitions.
What I would like to do would be to use Computed Muscle Control (CMC) in order to calculate the excitation of muscles given a certain trajectory.
What I have at the moment is the trajectory and GRFs.
My issue is that I do not really understand how I should structure the Residual_Actuators and the Tasks files.
- Residual Actuators: are they compulsory? I do not understand why muscles on their own should not be able to produce enough force for a walking movement. In case I have to add them, do I have to add a reserve actuator to each joint that is moving during the given trajectory?
- Tasks: it is the file indicated which coordinates have to be tracked. Do I have to include all the coordinates that change their value during the given trajectory? Or just some of them?
And about the weight: is it ok if I use weight = 1 for each coordinate or should I use a different value, higher/lower for some of them? IN case, how can I choose this value?
In the simulations I am running at the momento the main problems are that:
- OpenSim crutches saying that the model is not able to develop the required accelerations: do you know why it happens?
- In the simulations that reach an end the resulting movement is completely uncorrected with the model wriggling on himself.
Can anyone help me with these issues. I looked a lot on the internet too but I could not find specific information and guidelines about how to do CMC.
Thank you!
Francesca