Unstable 6DOF constraint

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dikobraz
Posts: 8
Joined: Thu Feb 19, 2009 3:01 pm

Unstable 6DOF constraint

Post by dikobraz »

I use Bullet 2.74 and am trying to implement simulation of the robot. For now, robot is presented as five cone shapes linked with generic 6DOF constraints. Limits of the constraints can be viewed on the screenshot.
blender_scr.jpg
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Blender file:
sausage.7z
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1) The problem occurs when I am trying to limit z-axis. Simulation becomes very unstable, both in blender(2.49b) and in my engine. Setting up small threshold (from -1.0 to 1.0 degree) limit the problem, but not eliminate it. Also, when using cylinders instead of cones, simulation seems to be more stable.

2) Also, I have problem implementing actuators(motors) in joints. I need something like this:
Image

The idea is to "lock" joint when actuator is inactive and to "unlock" joint rotation around specified axis and apply necessary forces when actuator is working, just like in real robots. As I understand btGeneric6DOFConstraint it is impossible to "unlock" arbitrary axis. Thanks for any solutions.
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