Wave-based control of flexible mechanical systems

Abstract

There are many contexts, from space structures to disk drive heads, from medical mechanisms to long-arm manipulators, from cranes to light robots, in which it is desired to achieve rapid and accurate position control of a system end-point by an actuator working through a flexible system. The system’s actuator must then attempt to reconcile two, potentially conflicting, demands: position control and active vibration damping. Somehow each must be achieved while respecting the other’s requirements. Wave-based control is a powerful, relatively new strategy for this important problem that has many advantages over most existing techniques. The central idea is to consider the actuator motion as launching mechanical waves into the flexible system while simultaneously absorbing returning waves. This simple, intuitive idea leads to robust, generic, highly efficient, adaptable controllers, allowing rapid and almost vibrationless re-positioning of the remote load (tip mass). For the first time there is a generic, high-performance solution to this important problem that does not depend on an accurate system model or near-ideal actuator behaviour.