Yes there is a method to stop your rigidbody toppling over. You can set the "Freeze Rotation" property, either in the rigidbody's inspector values, or via scripting.

You can then manually rotate the object around the Y axis using Transform.rotate, and you can rely on the object remaining upright at all times.

I was looking at this the other night and decided on something which is pretty obvious to me now :) :

• Get the Vector3 that you want to travel to
• Modify the Y-axis so that it is the SAME as the object you are moving.
• LookAt the modified Vector3 instead of the original.

Now when you LookAt, it will of course look at the x,z coordinates and keep the same y as the current object which effectively keeps the object upright in its current context.

You can't use Transform.rotate or Transform.translate if used Rigidbody. http://unity3d.com/support/documentation/Components/class-Rigidbody.html You can use Rigidbody.MovePosition or Rigidbody.MoveRotation, but better to use Rigidbody.AddRelativeForce or Rigidbody.AddRelativeTorque for right work physics. And only into FixedUpdate().

Code for correction needless Rigidbody roration:

Quaternion rot = rigidbody.rotation;
rot[0] = 0; //null rotation X
rot[2] = 0; //null rotation Z
rigidbody.rotation = rot;