# Thread: Feeding Coordinates to Pincher Arm.

1. Vacuum Tube
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## Re: Feeding Coordinates to Pincher Arm.

When the robot moves to a point, is it making reference to the tip of the gripper, or the centre of the gripper, or the 5th servo? Making progress just trying to set some limits, rather jerky and seems like its going to tear itself apart!

2. ## Re: Feeding Coordinates to Pincher Arm.

The IK engine assumes that the middle of the gripper is the end point.

What are you setting your delta value at?

Keep in mind that the delta value is not a direct velocity value, but a time value - so 2 movements with the same delta value will have 2 different speeds if they have 2 different distances to travel. So large movements will have a higher velocity than small movements. You may need to vary your delta based on how far the movement is.

3. Vacuum Tube
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## Re: Feeding Coordinates to Pincher Arm.

Originally Posted by kgranat
The IK engine assumes that the middle of the gripper is the end point.

What are you setting your delta value at?

Keep in mind that the delta value is not a direct velocity value, but a time value - so 2 movements with the same delta value will have 2 different speeds if they have 2 different distances to travel. So large movements will have a higher velocity than small movements. You may need to vary your delta based on how far the movement is.
Ok thanks.

Well that changes everything! Hmm, can't believe I've over looked that! I generally have it at 32, sometimes maybe a bit lower, I'll code in some variations depending on the distance moved.

It may also be because the board and robot can't keep up with the data I'm sending it. Leap is around 300fps, I've tried averaging 5 frames from the Leap, and just taking every 5th, doesn't really smooth it out.

Maybe some form of prediction, I've found if I'm moving my hand in one plane slowly the robot seems to jutter a few coordinates behind, rather than staying close to the finger. (I've already changed the fWait to false in MoveArmTo on the board itself, so it doesn't complete every coordinate I send it).

I also think I'm expecting to smooth movements from the servos, the 1mm steps are maybe to large, for what I'm trying to do.

Definitely haven't given up though, Im close!

Thanks again.

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