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Rigidbody hinged to moving kinematic rigidbody is NOT constrained
I have a very simple test case with two primitive cube rigidbodies connected via a joint.
Unity 4.0.1f2
Rigidbody A is the "wheel" - size = 1.5 x 0.5 x 1.5, and it has a Y-axis HingeJoint whose "Connected Body" = Rigidbody B
Rigidbody B is the "platform" - size= 0.5 x 0.1 x 0.5, and it is kinematic (isKinematic=true). An attached script tilts it by rotating its transform around X and Z.
default project physics/time settings
web-player build of this example (cursor keys tilt the platform)
As you can see, when the "platform" (RigidBody B) is tilted on X and Z, the "wheel" (Rigidbidy A) is not properly constrained to the kinematic RigidBody B! .... It 'wobbles' and can be seen intersecting with Rigidbody B.
According to the Rigidbody.isKinematic script manual page, "...connect a kinematic rigidbodiy to a normal rigidbody with a joint and the rigidbody will be constrained with the motion of the kinematic body."
I expect this to mean that my "wheel" connected via HingeJoint to a kinematic RigidBody should be constrained to the kinematic RigidBody and NOT move independently, except around it's hinged axis.
I have seen similar issues with RigidBody position and rotation constraints also... constraints are sometimes NOT observed, and things 'wobble'! This is very frustrating. Is this an expected behavior? Am I doing something wrong?
Your answer
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