Feedforward control of flexible manipulators

The design of feedforward controllers to control the tip position of single-link flexible arms is developed. The objective is to drive the tip position along a commanded trajectory without any oscillations at the tip. The method is based on the well-known dynamics model inversion technique. Since the controllers are implemented on a computer, the dynamic inversion of the single-link flexible arms is studied from a discrete point of view. A general method to obtain a feedforward controller is developed, even in the case when the system transfer function is of nonminimum phase. The method is general in the sense that it removes oscillation in the arm with any number of vibration modes. It is shown that the input preshaping scheme developed by N.C. Singer and W.P. Seering (1990) is a special case of this method. The design technique is illustrated with numerical examples, and a comparison with the input preshaping method is carried out