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We have a simple robotic model with revolute joins in v-rep. The joints are in force/torque mode, and they are controlled via non-threaded child script using simSetJointTargetVelocity function of the simulator. The collision is enabled in the model, and some toy weights are set to the connecting poles.

The error we have is that the blue part of the joint (the movable part) "wiggles" around and eventually out of the red part of the joint (the fixed case). Here's a screenshot showing the error.

enter image description here

(The blue part of the upper joint should be inside the red part, as is in the lower joint)

How to fix the moving part of the joint so that it doesn't move around, but only rotates as requested by the velocity settings?

Ben
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Gyfis
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1 Answers1

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What do you mean by "toy weights" ?

You should keep in mind that physical simulations are relatively fragile and that some restrictions apply. In your case, it seems the masses you set are making the simulation behave strangely. Try to keep the mass ratio between linked objects below 1/10.

You can also modify the simulation settings, to increase its precision. You can do that in the simulation settings dialog (http://www.coppeliarobotics.com/helpFiles/) and in the general dynamics properties dialog. You can also try if your simulation works better with another physics engine than bullet (I suggest "Newton").

For more info you should take a look at http://www.coppeliarobotics.com/helpFiles/en/designingDynamicSimulations.htm, especially at the "Design considerations" section.

openTankist
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  • Thanks for the reply! For the toy weights - I think we did have a considerably different weight on the poles and on the planes. We later settled for a different engine just like you described which worked better (though not perfect) for the simulation we needed to perform. – Gyfis Nov 23 '16 at 10:38