Collision detection

CoppeliaSim can detect collisions between two collidable entities in a flexible way. The calculation is an exact interference calculation. Collision detection, as its name states, only detect collisions; it does however not directly react to them (for collision response, refer to the dynamics module).

[Collision detection between two manipulators]

Using the API function sim.checkCollision, one can easily detect collision between entities, for instance collision detection between a robot and its environment, from within a child script, in each simulation step:

function sysCall_init() local robotBase=sim.getObject('/robotModelAlias') robotCollection=sim.createCollection(0) sim.addItemToCollection(robotCollection,sim.handle_tree,robotBase,0) end function sysCall_sensing() local result,pairHandles=sim.checkCollision(robotCollection,sim.handle_all) if result>0 then print('Robot is colliding. Colliding pair is '..getAsString(pairHandles)) end end

One can also temporarily modify the color of objects or whole collections, in order to visually indicate a collision:

function changePairColor(entityPair,colorPair) originalColorData={} originalColorData[1]=sim.changeEntityColor(entityPair[1],colorPair[1]) originalColorData[2]=sim.changeEntityColor(entityPair[2],colorPair[2]) end function restorePairColor() if originalColorData then sim.restoreEntityColor(originalColorData[1]) sim.restoreEntityColor(originalColorData[2]) originalColorData=nil end end function sysCall_init() local robotBase=sim.getObject('/irb360') robotCollection=sim.createCollection(0) sim.addItemToCollection(robotCollection,sim.handle_tree,robotBase,0) collisionColors={{1,0,0},{1,0,1}} -- collider and collidee end function sysCall_sensing() local result,pairHandles=sim.checkCollision(robotCollection,sim.handle_all) restorePairColor() if result>0 then -- Change color of the collection and the collidee: changePairColor({robotCollection,pairHandles[2]},collisionColors) -- Change color of the collider and collidee objects: -- changePairColor({pairHandles[1],pairHandles[2]},collisionColors) end end function sysCall_cleanup() restorePairColor() end

CoppeliaSim's collision detection functionality is also available as stand-alone routines via the Coppelia geometric routines.

See also the add-on in [Menu bar --> Modules --> Geometry / Mesh --> Collision check ] that allows to quickly check for self-collision, collision with the environment, or collision between two entities.