V-REP Forum

Posted: **07 Feb 2018, 09:45**

Hi,

I am new to Vrep and have started working on it recently.Going through the forum I found a file which was trying something same as I intend to do. I have modified the file and am working on it now.I want to create Collision Pairs and want to avoid the 'self Collisions' happening in UR5 linkages. I tried adding the collision pair.However, it says the Collection is missing.
It might be something very trivial that I am missing.Any help would be greatly appreciated.
Following is the link to model:
https://drive.google.com/file/d/1vb_fnF ... sp=sharing

Also,
jointPositions=simGetConfigForTipPose(number ikGroupHandle,table jointHandles,number distanceThreshold,number maxTimeInMs,table collisionPairs)
is allthat has to be added.Am I correct in this interpretation of syntax?

Thanks in advance!

Posted: **08 Feb 2018, 08:22**

Hello,

first, make sure there is no other collection with the same name when trying to create one. Next, make sure to carefully read this page, the section Access from associated code: since your script is attached to an object named UR5#0, your code should rather look like:

Code: Select all

collisionPairs={sim.getCollectionHandle('CollectionName#'),sim.handle_all}

If you specify a collection name CollectionName, it will try to retrieve CollectionName#0, which doesn't exist.

Finally, make sure to destroy the collection at the end of simulation with:

Code: Select all

function sysCall_cleanup()
    sim.emptyCollection(UR5Collision)
    sim.removeCollection(UR5Collision)
end

There is however a bug with threaded scripts, since they will be destroyed without running the sysCall_cleanup section in some situations, as I just noticed... looking into it.

Cheers

Posted: **08 Feb 2018, 09:10**

Hello again,

actually, it should work fine in V-REP V3.5.0, if you format your threaded child script like:

Code: Select all

applyJoints=function(jointHandles,joints)
    -- ...
end


IKMovement=function(x,y,z)
    -- ...
end


function sysCall_threadmain()
    vel=180
    accel=40
    jerk=80
    currentVel={0,0,0,0,0,0,0}
    currentAccel={0,0,0,0,0,0,0}
    maxVel={vel*math.pi/180,vel*math.pi/180,vel*math.pi/180,vel*math.pi/180,vel*math.pi/180,vel*math.pi/180}
    maxAccel={accel*math.pi/180,accel*math.pi/180,accel*math.pi/180,accel*math.pi/180,accel*math.pi/180,accel*math.pi/180}
    maxJerk={jerk*math.pi/180,jerk*math.pi/180,jerk*math.pi/180,jerk*math.pi/180,jerk*math.pi/180,jerk*math.pi/180}
    targetVel={0,0,0,0,0,0}

    jointHandles={-1,-1,-1,-1,-1,-1}
    for i=1,6,1 do
        jointHandles[i]=sim.getObjectHandle('UR5_joint'..i)
    end

    IKHandle=sim.getIkGroupHandle('UR5_IK#')
    dummyHandle=sim.getObjectHandle('UR5_target#')

    console_mode=1+2+4
    ConsoleHandle=sim.auxiliaryConsoleOpen("Debug Console",5,console_mode)
    UR5Collision=sim.createCollection('CollectionName',0)
    sim.addObjectToCollection(UR5Collision,sim.getObjectHandle('UR5#0'),sim.handle_tree,0)
    collisionPairs={sim.getCollectionHandle('CollectionName#'),sim.handle_all}
    print(collisionPairs)

    for i=-0.55,0.95,0.05 do
        a=math.sin(2*math.pi/90*i)
        IKMovement(i,a,1.3)

    end

end

function sysCall_cleanup()
    sim.emptyCollection(UR5Collision)
    sim.removeCollection(UR5Collision)
end

Which is the new and better way of doing, starting with V-REP V3.5.0: i.e. using nothing else but functions in scripts.

Cheers

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Collection does not exist

Collection does not exist

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Re: Collection does not exist