Using a Hinge Joint for a backhoe arm.

Unity Engine
1

Hi. I am experimenting with making a backhoe sim. Right now I am having difficulty with Hinge Joints.

I have a backhoe model made in Maya with pivots set for each arm and a parented hierarchy. This works well in Maya but Unity doesn’t appear to support pivot points that aren’t centered in the middle of geometry.

Now I am experimenting with multiple Hinge Joints for the arm and linking them together with the connected body attribute. However I am getting funky results from the Hinge Joint. The Limits don’t seem to have much effect.

Also, after I apply a force on the hinge joint it goes all wiggley and then flails around slowly under it’s own control.

Here is a screen capture of what I mean using primitive cubes.

http://www.doverstudios.com/andrew/movies/UnityHingeJoint.mov

Do you have any hints on how to tame the hinge joint?

Thanks,
Andrew

2

Actually we do. What might be confusing you is that the handle by default is drawn a the center of the geometry. However this can be turned off by clicking on the pivot axis button at the main toolbar.

If you are running into issues with the hinge joint, most likely you are connecting them to the wrong rigidbody. Sometimes you create loops between the different joints or simply connect to another one than you intended. I would connect them step by step. Start by making one hinge joint that is setup 100% correctly and has the right feel. When you have done that, add the next one.