Fixing gripper movement

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mohammadhosseink
Posts: 20
Joined: 11 Sep 2022, 06:48

Fixing gripper movement

Post by mohammadhosseink »

Hello Coppelia,

I am using ROBOTIQ-85 to do a grasping task. When I close the gripper, the fingers move forward while getting closer to each other. I don't want to have this forward movement and I want the fingers to close without this. I believe there should be an easy way to fix this dynamically but I cannot find it.

Please tell me if I didn't properly clarify my intention of "forward movement". Here is a video that may help: https://drive.google.com/file/d/1bbGKfe ... sp=sharing

You can see in the video how the fingers not only close but also have a movement forward, making them go beyond the purple dummy instead of meeting each other where the purple dummy is placed.

Thanks in advance,

fferri
Posts: 1193
Joined: 09 Sep 2013, 19:28

Re: Fixing gripper movement

Post by fferri »

Hi,

you can simply have the gripper move backwards to compensate for the gripper's fingers forward movement.

Since the gripper is attached to an arm, you can move the arm via IK, e.g. before calling simIK.handleGroup you would set the position the "tip" dummy so that it's always in the middle of the gripper's fingertips:

Code: Select all

local l=sim.getObjectPosition(LfingerTipVisibleHandle,-1)
local r=sim.getObjectPosition(RfingerTipVisibleHandle,-1)
local tipPose=sim.getObjectPose(simTip,-1)
for i=1,3 do tipPose[i]=(l[i]+r[i])/2 end
sim.setObjectPose(simTip,-1,tipPose)
simIK.setObjectPose(ikEnv,ikTip,-1,tipPose)
--simIK.handleGroup(....)
Image

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