Synthesis of Optimal Preview-based Tracking Compensators

Hoover D., R. Longchamp and J. Rosenthal. Two-Degree-of-Freedom l2-Optimal Tracking with Preview. Automatica, 40, 155-162

Holmberg U. and P. Myszkorowski. Comment on: Precision Tracking Control of Non-minimum Phase Systems with Zero Phase Error. Int. J. Control, 64, No 5, 995

Holmberg U., P. Myszkorowski and R. Longchamp. Tracking Control with a Smooth Transient Response. 13th IFAC World Congress, preprints, San Francisco (July 1996)., Vol. C, pp. 307-311

Holmberg U., P. Myszkorowski, Y. Piguet and R. Longchamp. On Compensation of Nonminimum-phase Zeros. Automatica, Vol. 31, No 10, pp. 1433-1441 David Hoover, LONGCHAMP Roland

When a reference signal is known a fixed time in advance, it is possible to exploit this early knowledge which is known as “preview”. This project studies how preview may be used to improve tracking response for fixed-order two-degree-of-freedom controllers, and in more general cases, also with order limitations. A method is proposed which allows the preview concept to be incorporated into the design stage of a two-degree-of-freedom controller. A method is also presented which may be used to design preview-based compensators for existing arbitrary closed-loop systems which do not exploit preview information. The approach often results in considerable tracking improvement while preserving robust asymptotic tracking properties as well as closed-loop properties like robustness and stability. The method allows the designer considerable freedom in the choice of optimization criteria, since general convex optimization routines are used to find the optimal compensator. Also, the generality of the convex optimization approach is such that a number of previous preview related results may be incorporated into a standard framework.