Robustness of Sampled-data Control Systems

Abstract

Uncertain physical parameters of a continuous-time plant enter exponentially into the characteristic polynomial of the discrete-time system. A polynomic approximation can be achieved by the truncation of a Poisson series representation of the z-transfer function. This approach was proposed in an earlier publication. In the present paper two practical examples are studied by using only one or two terms of the series: In the first example of a track-guided bus the approximation is very good, in the second example of a vibration suppression control system for a helicopter sampling was relatively slow for the plant dynamics and the approximation would require more terms of the series and unreasonable computational effort.