Refactoring collision detection using Geometry primitives (such as capsule) #290
Description
Today Collision detection in moveit is still based on user defined mesh's.
Even with FCL and all the mesh optimization it is still very expansive computationally to check collision .
A simple solution exists. Use primitives' collision objects instead of meshs.
The combination of capsules and obb and spheres yields very fast computation time and very good approximation,
This can potential yeild few order of magnitude in run time.
(i was working in a company were we developed our own collision detection system, and their we did this move, the results were more then 100 time fold for a single quarry (for a large cell).
Further more it is quit easy to automatically generate a primitive geo representation from the mesh , their are vey stable alg from gaming industry for that, and
The challenge would be to implement the capsule obb collision tests as in the current collision detection libs such as Bullet and FCL use very inefficient algorithms. I have recently wrote a new alg for that that might be much faster, But also the existing "slow" methods are much faster then mesh methods.
More for the future:
Improve the moveit setup assist to :
- generate the primitive collision object representation, and save that in a config file, validate the result
- while testing for the self collision matrix , use the data to generate a calculate the
probability of a to collision objects in the cell to collides, with this a collision collision (order of checking the collision pairs) can be generated. changing the order of checking the individual quires, dosent change the alg correctness, but it will change the avg run time on colliding states , as pairs that have heiger probability to collide will be evaluated first.
Multiple collision queries:
Write a version that checks the collision state of more then one state at onces,
this open an entire world of optimizations, that can yield much faster run time then a signale query (on average)
GPU implementation:
with the collision system is based only on OBB (and aabb), capsule and sphere ,
its fairly easy to implement the collison test for that on GPU (as an option)
Today open source very fast code for capsule capsule collision detection exists for GPU,
they are uncomparble to the run time on CPU, so extending it to the other needed collision primitives should be feasible, and not to hard, test wise as we have the old mesh implementation, and the CPU new one it will be easy to unit test the GPU version.
Continues Qury:
given the next state and current state check that no collision is happening while moving from one to the other.
under the assumption of a linear move between states (which works while the time difference between the states is small )