Method to Locate Footstep

Frederick84

Hi,

I am working on a project to collect data on walking gait of patient, ie stoke patient. I need solution to locate the position of the patient's feet and the distance apart by using just distance sensor.

any one got good idea ??

minger

How precise, complex are you looking for? Would something as simple as dipping their feet in ink and having them walk on paper work?

Frederick84

Cause, Im planning to place a distance sensor on the foot, then use them to meaure the distance, however it cant locate the position.

As i need the data to be transfer via RS232 to matlab to generate the results, therefore I cant use the method you suggested.

Thank for the input.

Danger

Perhaps it would be useful to contact an optical effects company such as Industrial Light and Magic. A lot of CGI characters are based upon motion studies of live actors. I think that most of those are accomplished using laser scanning, but the first efforts involved sensors such as magnetic, radar, acoustic, and simple radio transmitters. A professional in the business might be able to give you some really great insights.
My personal approach, being an uneducated amateur, would probably be to use an RF transmitter with triangulating receivers.

berkeman

I like Danger's ILM idea. You can use the video pickup technique, which is very well developed. Put little white marker balls on parts of the feet and legs, and use a video camera to film the patiet's gait on a treadmill. You can film from both sides if bilateral data are important.

Danger

Actually, the only reason that I didn't mention optical sensing is because I considered it to be two-dimensional v/s the 3 that Frederick seems to need. Multi-angle vision would cover that nicely, as long as the inputs remain properly co-ordinated. Good call.

timmay

Gait analysis is often carried out using pressure sensing panels or footplates. One system I've used before is made by Tekscan.

Alternatively, a very basic system of digital image correlation using two cameras could be carried out as suggested above. Have a marker on both shoes/feet, make sure your two cameras (mounted at an angle of ~20deg to each other or so) can both see the marker clearly, then track the motion of the marker between synchronised frames. DIC does this with many many markers, and in a stereoscopic configuration of cameras can give you three dimensional position data.