Speed up collision checking

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RoboTomo
RoboTomo on 11 Nov 2021
Edited: RoboTomo on 18 Nov 2021
I am using Matlab's "checkCollision" function with four additional collision objects and a UR5 robot. Function is working great and returns logical 1 or 0, which is later used in the program (I am checking overall reachability of the workpiece).
The only problem I am facing is computation time. I already limited points on the workpiece but it still takes too long, 80% of the time is used only for collision checking.
Is there a way to speed things up? If not, is there any other available collision checking library (maybe with use of voxels or spheres) which works with Matlab in similar fashion?

Accepted Answer

Karsh Tharyani
Karsh Tharyani on 11 Nov 2021
Edited: Karsh Tharyani on 17 Nov 2021
Hi RoboTomo,
Thanks for your question.
  • There were some improvements made in performance for checkCollision in R2021b. Try and see if it meets your expectation.
  • You can also try turning "off" self-collision checking if you are confident that the configurations you pass to the collision checking routine don't result in the robot colliding with itself. See ("IgnoreSelfCollision") here: https://www.mathworks.com/help/robotics/ref/rigidbodytree.checkcollision.html#namevaluepairarguments
  • Alternatively you can try generating a MEX for an entry point function (See rbtCheckCollision) that accepts a configuration and returns whether the robot is in collision.
function isColliding=rbtCheckCollision(config)
% Use persistence if the robot and the environment are not changing.
persistent rbt env
if(isempty(rbt))
rbt=importrobot("universalUR5.urdf","DataFormat","row");
end
if(isempty(env))
c1=collisionBox(0.1,0.1,0.1);
c1.Pose=trvec2tform([0.2,0.2,0.4]);
c2=collisionSphere(0.3);
c2.Pose=trvec2tform([0.4,-0.2,0.4]);
env={c1,c2};
end
isColliding=rbt.checkCollision(config,env);
end
>> codegen rbtCheckCollision -args {zeros(1,6)}
I would be glad if you could also reach out to Technical Support and convey any performance requirements that you have for your use case, and we would be happy to enhance checkCollision in a future release of MATLAB.
Best,
Karsh
  5 Comments
RoboTomo
RoboTomo on 18 Nov 2021
Edited: RoboTomo on 18 Nov 2021
Ok thank you for clarification, I was already thinking that there was new UR5e model somewhere. Yes, visuals are working great, I was using this at the beginning to verify objects and collision detection.
I modified my program a little bit and separated collision detection. For calculating one configuration it now needs approx. 0.01 seconds which I think is good enough.

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