Path following for mechanical systems: Experiments and examples

This paper concerns the design of path following controllers for mechanical systems. Our method is to find a coordinate and feedback transformation that puts the mechanical system in a convenient form for path following control design. In this form, linear and controllable subsystems govern motions toward and along the path. We choose a particular "virtual output" to perform input-output feedback linearization, and characterize when this virtual output can be used. We apply this technique to a planar five-bar linkage robot, and implement it experimentally, highlighting behaviour fundamentally different from standard tracking control. In simulation, we further illustrate our approach on an underactuated five-bar robot with a flexible link.