Let me make sure one thing:
Please provide the following information:

1. Dimension of the system (at least r1,r2,r3)
2. Does the outer most one can only rotate in YAW AXIS?
3. Is it a static system, only need to be able to set the angle for Pitch, Roll and Yaw angle?
Or there is(are) initial angualr velocity for a dynamic system? What are those values? What are the differential equations according constraints for your system.

Because I have never play with such device before, I do not have any ideas about the physics model (constraints) for the system. I need physics model to create the simulation.

The rotation axes for the following two images are not the same. Which one is similar to your gimbal?

The following is a static version. Click [eye]

translate strings in simulation to different language format before download
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1092.6kB):double click downloaded file to run it. (3 times by 2 users) , Download EJS source View EJS source
[/eye] to view it.