Algodoo

The orange circle has the controller for the arm itself. The purple circle has the controller for its position. The red square and the floor have some logic to keep the derivative gain from going crazy. The red square also has a definition for its position. Arm variables are xe, ye, and phi. I still don't have a good grasp on variables and how to create them so they stick with a scene, so if you experience any trouble, try entering the console and defining each variable manually.