Avoid self-collision for manipulator task about crocoddyl HOT 3 CLOSED

After some investigation and tests concerning my questions, I came to the conclusion that, indeed, if you specify state bounds (e.g. limit max and min joint positions and angular velocities for a manipulator), crocoddyl seems to automatically includes self-collision avoidance in terms of those soft constraints. This is quite interesting since, at least for me, I didnt saw a hint to that anywhere? Did I miss something? Or am I completely mislead?

from crocoddyl.

Hi @ThorbenPultke,

We are happy that you find useful Crocoddyl and we welcome you to contribute to our project.

I am not sure if you have sorted out your doubts; however, let me explain you a few things.

The above-mentioned example adds a quadratic penalisation (soft constraint) to the robot's state limits. It encourages the solver to find solutions that don't violate the joint limits, for instance, but I wouldn't say its purpose is to model self-collision (soft-)constraints. Self-collision involves checking whether two or more geometries are colliding.

Crocoddyl also supports the evaluation of self-collision constraints. This can be done through the ResidualModelPairCollision class (see https://github.com/loco-3d/crocoddyl/blob/master/include/crocoddyl/multibody/residuals/pair-collision.hpp). Note that this class is compiled when you have installed Pinocchio with HPP-FCL support.

Finally, we are working on novel solvers to handle efficiently any type of constraint.

If this reply answers your questions, then I would ask you to kindly close this issue.

Thanks,
Carlos

from crocoddyl.

Hi Carlos!
Thank you so much for your detailed explaination. I indeed was quite confused with the comment "cost for self-collision"

I now managed to include soft constraints via the cost function with your mentioned class to avoid those self-collisions. Thanks again for your help! :)

Thorben

from crocoddyl.