creating human limb models and movement

I'm an engineering professor who is looking to help my students develop a system where they could measure specific human body parts and have those figures transfer to a model. Ideally the model could then move and indicate points of stress. This may be something that can be done using simulink or possibly it is something that someone who is more familiar with human animation could refer me to an appropriate program for my needs.

We are working with a research lab in the University that does movement and fitting of artificial limbs, and movement studies with live motion capture. We have been asked to develop a tool that measures limb circumference at a series of locations, and also can apply a pressured squeeze at that location to determine how much 2 or 4 pounds of pressure changes the circumference. This is used in a number of different ways from a clinical standpoint, from determining fluid retention, muscle mass, and specifically for this project, the firmess of the risidual limb after amputation for the fitting of an artificial limb.

The fit for an artificial limb is critical, and can change depending if the surgical site is fully healed and depending on fluid, the fit needs to be adjusted for "firm "or "squishy" characteristics. I would like to be able to take the data generated by the measuring tool, and input that into an animation program to create a realistic representation. Ideally, the program would allow that generated 3D image to be modeled in a walking form so that adjustments can be made to improve the movement and fit at a prothestic limb, and possibly show stress points or points where the fit could be improved. It would also be fitting ( pun intended) if the motion of a soft and puffy limb movemnt could be illustrated as being different from a firm limb while in motion.

This just seems like something that is feasible with the simulink products, but I don't know if anything like this can be done, or has been done with them. If they can't then knowing how close I could get to this ideal using which specific product would be helpful, or if anyone knows of another mathematical image generation program, I would appreciate some guidance.

[Thomas]

Thank you Star for the quick response. I will look in the exchange for any models that have been created. We are looking to have the data changes drive the simulator instead of trying to take real time data during mivement. The intention is to develop 3d midifications that client and therapist feedback can fine tune once a casting has been made or eventually a 3d printed model to imbed sensors. If anyone knows of direct models for anatomy that exist, I would appreciate a link if you have one

Answer 1

[Star Strider]

First, I would begin with a PubMed search. This seems to be an area of active research, so there should be a plethora of information on your intended areas of enquiry. It will also guide you to the most appropriate approaches to your problem.

To the best of my knowledge, MATLAB can certainly do everything you need, including the image and signal analysis. I would search the File Exchange to see what user-contributed routines might already be available for what you want to do.

I’ve seen a number of motion capture questions here (most involved processing the position signals after initial acquisition and analysis), so those techniques seem to be well-established.

To determine the volume and circumference changes in response to pressure, I would consider ultrasound imaging (unless the literature suggests otherwise). It will also provide information on the conformational changes in the limb in response to the load you impose, and can do it at several levels proximal to, at, and distal to the region of the load. You will also have to consider blood flow and perhaps tissue motion, so ultrasound with Doppler capability will be necessary.

Living systems can be difficult to study because they evolved to be actively resilient to myriad external influences, and are therefore highly adaptive, nonlinear and generally nonstationary. They will provide you with hours of fun and fascination as you identify, model, and simulate all of the dynamics that turn out to be significant in the systems you are studying. Depending upon what signals you are acquiring, it may be difficult to distinguish the system dynamics from the transducer dynamics, so consider that in your instrumentation design.

[Star Strider]

Thomas’s Comment is replicated here...

Thank you Star for the quick response. I will look in the exchange for any models that have been created. We are looking to have the data changes drive the simulator instead of trying to take real time data during mivement. The intention is to develop 3d midifications that client and therapist feedback can fine tune once a casting has been made or eventually a 3d printed model to imbed sensors. If anyone knows of direct models for anatomy that exist, I would appreciate a link if you have one

[Star Strider]

My pleasure.

You will likely end up having to take real time data. You will first need to create a biomechanical model of the system you are studying, and then estimate the model parameters from the data you acquire. With the estimated parameters, the simulator will help you understand your data.

Anatomic models likely do exist that can help guide your development. I would start with the NIH Visible Human Project. Note that creating 3D images from CT scans in MATLAB does not appear to be a trivial exercise (I’ve never attempted it but there are many threads here from those who want to).

I suggest that you look through the literature in PubMed thoroughly to see what has already been done in this area.