Design of bi-causal inverse models for non-minimum phase systems and its applications to precision tracking control

In this paper, an approach is proposed for the design of approximate inverse models for the controlled systems that have real and/or complex conjugate unacceptable zeros. The proposed approach utilizes a bi-causal formula to construct the inverse model, therefore, it can be applied to the design of both feedforward and feedback controllers. A design example is used to illustrate the proposed design approach. Using the derived optimal solution, a feedback controller and a feedforward controller are designed for an electrical DC servomotor. The tracking performance of the designed system and its robustness to parameter variations are examined through computer simulation and experimental verification.