Computing of huntcrossley force

[Samane Amini]

Hi
I want to measure the huntcrossley force from contacts which is implemented on rear and front of legs(right and left). In fact, I simulate forward dynamic so computing GRF is necessary to control of joints. I exactly implement contacts on the toes and calcns. from contact modeling point of view, as contact sphere and contact half sphere meet together, hunt crossley force would be non zero. but in my case, even if the foot is on ground (contact sphere meet to contact half sphere), the hunt crossley is zero!!!. huntcrossley would be non-zero, unless the toes go under the ground surface.
I would like to know if how should set the contacts or where should implement contacts to have non-zero force when the foots be on ground?
also, I'd like the foot not to go under the ground during walking

[Thomas Uchida]

Please see this example if you have not already: "Building a Dynamic Walker in Matlab", https://simtk-confluence.stanford.edu/d ... +in+Matlab.

[Samane Amini]

Hi Thomas Uchida
as you mentioned, I saw "Building a Dynamic Walker in Matlab". But I want to implement contact between feet and ground, not to bodies. so I don't know what location I could set the contacts on feet to avoid ground penetration and when feet is on ground, hunt crossley force has nonzero value.

[Thomas Uchida]

as you mentioned, I saw "Building a Dynamic Walker in Matlab". But I want to implement contact between feet and ground, not to bodies.

I don't know what you mean. The example does in fact define contact between the feet and the platform.