How to break the joint between two rotating sphere

2021-09-03T13:54:10+00:00

Hi everyone,

I would like to do a quite simple simulation but I fail to create it... May be my understanding of bullet is wrong.

I would like to create two sphere connected by a fixed joint, the sphere is located at (0,0,2) and the second one at (0,0,2). These two spheres are rotating at a constant speed around the (0,0,0) point. At some point, I would like to break the joint and let the sphere move away.

There is no gravity

I tried to create a multibody:

Code:

sphereRadius = 0.5sphere_base = p.createCollisionShape(p.GEOM_SPHERE, radius=sphereRadius)sphere_1 = p.createCollisionShape(p.GEOM_SPHERE, radius=sphereRadius)sphere_2 = p.createCollisionShape(p.GEOM_SPHERE, radius=sphereRadius)mass = 1visualShapeId = -1# Link relatedsphereUid = p.createMultiBody(baseMass = mass,                baseCollisionShapeIndex = sphere_base,                baseVisualShapeIndex = visualShapeId,                basePosition = [0, 0, 0],                baseOrientation = [0, 0, 0, 1],                linkMasses= [1, 1],                linkCollisionShapeIndices=[sphere_1, sphere_2],                linkVisualShapeIndices=[-1, -1],                linkPositions=[[0, 0, 2], [0, 0, -2]],                linkOrientations=[[0, 0, 0, 1], [0, 0, 0, 1]],                linkInertialFramePositions=[[0, 0, 0], [0, 0, 0]],                linkInertialFrameOrientations=[[0, 0, 0, 1], [0, 0, 0, 1]],                linkParentIndices=[0, 0],                linkJointTypes= [p.JOINT_FIXED, p.JOINT_FIXED],                linkJointAxis=[[0, 0, 1], [0, 0, -1]])

It works but I do not know how to break the joints...
I understood that the constraint is may be a better option. I know I can remove a constraint. However, I am not able to obtain the proper rotation around 0.

Code:

sphere_1 = p.createCollisionShape(p.GEOM_SPHERE, radius=sphereRadius)sphere_0_uid = p.createMultiBody(baseMass = 1,                baseCollisionShapeIndex = sphere_1,                baseVisualShapeIndex = -1,                basePosition = [0, 0, 0],                baseOrientation = [0, 0, 0, 1])sphere_1_uid = p.createMultiBody(baseMass = 1,                baseCollisionShapeIndex = sphere_1,                baseVisualShapeIndex = -1,                basePosition = [0, 0, 2],                baseOrientation = [0, 0, 0, 1])                c1 = p.createConstraint(    parentBodyUniqueId = sphere_0_uid,     parentLinkIndex = -1,     childBodyUniqueId = sphere_1_uid,     childLinkIndex = -1,     jointType = p.JOINT_FIXED,     jointAxis = [0, 0, 0],     parentFramePosition = [0, 0, 2],     childFramePosition = [0, 0, -0.5])                     OMEGA = 3.14p.resetBaseVelocity(sphere_0_uid, [0, 0, 0], [0, OMEGA , 0])

Any advices to do this basic simulation?

ps: I don't display it but I have set all dynamic parameters (Friction, damping, stiffness) = 0. I would like to see vacuum physics

Statistics: Posted by Nanospin — Fri Sep 03, 2021 1:54 pm

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How to break the joint between two rotating sphere