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hungpham2511 / toppra

robotic motion planning library
https://hungpham2511.github.io/toppra/index.html
MIT License
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Can TOPPRA solve the dynamic model considering friction? #32

Closed Linjackffy closed 5 years ago

Linjackffy commented 5 years ago

If I want to consider Coulomb and Viscous friction into dynamic model:

M(q) q_ddot + q_dot^T C(q, q_dot) q_dot + g(q) + Dv q_dot + Fc *sign(q_dot) = torque

where M(q) , C(q) and g(q) are the same representation in tutorial of Second-Order Constraint. Dv and Fc are coefficients of viscous and Coulomb friction, respectively.

Can TOPPRA solve it?

hungpham2511 commented 5 years ago

Unfortunately TOPPRA cannot solve problems with viscous friction. However, it can solve problems with dry friction.

Linjackffy commented 5 years ago

I just try to add viscous and Coulomb friction in the Second-Order Constraint, TOPPRA return a result. From parametrization plot, it seems the given path is time-parameterizable, but the torque does not satisfy constraint. Anyway, thank for your reply.

hungpham2511 commented 5 years ago

Unfortunately, the current implementation of TOPPRA cannot handle dry friction. What I meant is TOPPRA as an algorithm can solve it, not this package.

Should you wish to implement this functionality, I would be very happy to accept a pull request. Thanks!

Linjackffy commented 5 years ago

TOPPRA is most stable and efficient algorithm for robot motion planning that I've ever used. It's my honor to contribute to this project. I would try to implement dry friction into TOPPRA.