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Difference between adding object and attaching it using MoveIt ?

asked 2020-12-28 07:10:20 -0600

erdisayar gravatar image

Hello, I am following the MoveIT Python tutorial

According to the tutorial, we can add an object and attach it later. However I did not understand what is the difference between adding and attaching an object.

For example; I added an object firstly as I showed in the following picture. MoveIt detects the collision and I cannot close the gripper.

image description

If I add the object and attach it (to the world frame ), robot exhibits the same behavior.

image description

So what is the difference between adding object and attaching it ?


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answered 2020-12-29 10:31:56 -0600

fvd gravatar image

When you add aCollisionObject to the planning scene, it exists as a stationary object in the scene that the robot can collide with. When you attach a CollisionObject, it moves with the robot link that it is attached to.

In your case, you placed your object at a position where it collides with the robot. You could change the object's position, or allow collision with the robot gripper link. The latter is more useful if you want to grasp the object.

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If I attach the object in a stationary frame (/world), Then can we say that there is no difference between attaching an object to the stationary frame or adding object in scene without attaching it?

erdisayar gravatar image erdisayar  ( 2021-01-08 11:11:48 -0600 )edit

Yes, currently there is no meaningful difference. If you publish a CollisionObject to the planning scene, the object is by default stationary in the planning frame (world), and attaching an object to a fixed frame is equivalent.

fvd gravatar image fvd  ( 2021-01-09 10:58:34 -0600 )edit

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Asked: 2020-12-28 07:10:20 -0600

Seen: 366 times

Last updated: Dec 29 '20