Measure relative movement between exoskeleton and human body

Hi all, I’m just beginning to use Anybody and meet some problem; I want to measure relative movement between exoskeleton and human body,and have cerated the coupling model.

But I don't know how to capture the relative movement between the exoskeleton and the human body through gait experiments. I think it is possible to attach markers to the exoskeleton and the human body to capture the relative motion, but I don’t know if this method is feasible? Because of the exoskeleton , some markers on the human body are blocked.

I sincerely hope to get your advice on measuring relative movement between human and exoskeleton.

Kind regards

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Hi Ludwig,

Just a small administrative thing first - this is a professional forum, please add your affiliation to the profile.

The relative motion - it is best to have measured motions of both, exoskeleton and human, in the best way possible. But details will depend on the actual experimental setup and exoskeleton design. From your very generic description i can only guess that this is a lower extremity exoskeleton, but not whether it is feasible or not.

AnyBody MoCap models are setup to handle dropping out markers and you can manipulate weights of the less reliable markers, but it will, of course, depends on how large the error is, how long the drop-outs are, and so on. And yes, you can drive the exoskeleton with the markers, if that was the question, - you would add them to the exoskeleton segments with some minor modifications of the code. Typically you need at least 3 markers per each segment, unless you have perfect or close to perfect mechanical joints between segments - then you may need less, but you would need to provide sufficient to kinematically describe free degrees of freedom. Please also revisit this tutorials to understand how we drive models.

Kind regards,

Hi Pavel

Thank you for your reply, I will add my information, I have attached the exoskeleton to the Human in Anybody, I want to know if it is feasible to capture the relative movement by attaching markers to the Human and the exoskeleton separately through gait Experiments. The exoskeleton can put markers on its side to get its movement, but because of the exoskeleton, I cannot put markers on the human body, and some positions are blocked by the exoskeleton. Is there any good way to solve this problem? Or how to get the relative motion between human and exoskeleton through Anybody? Thanks you very much.
Kind regards;

Hi Ludwig,

If you want to measure the entire relative motion you will need enough markers on both exo and human, then this is possible. Then the relative motion can be measured in the model with an AnyKinLinear or AnyKinRotational.

If on the other hand there is not enough markers you can add come constraints between exo and human ( it sounds like you already did this). Then some DOF will be measured others will be constrained to some value.

Please see this wiki page on how to connect an exo to a human model.

Best regards

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