Transient response control of two-mass system via polynomial approach

This paper discusses the application of polynomial method in the transient response control of a benchmark two-mass system. It is shown that transient responses can be directly addressed by specifying the so-called characteristic ratios and the generalized time constant. The nominal characteristic ratio assignment (CRA) is a good starting point for controller design. And the characteristic ratios with lower indices have a more dominant influence. Two practical low-order control configurations, the integral-proportional (IP) and modified-integral-proportional-derivative (m-IPD) controllers are designed. The primary design strategy of the controllers is to guarantee the lower-index characteristic ratios to be equal to their nominal values, while the higher-index characteristic ratios are determined by the interaction with the generalized time constant and the limits imposed by zeros, a specific control configuration, etc. The demonstrated relationship between the transient responses and the assignments of characteristic ratios and generalized time constant in simulation and experiments explains the effectiveness of the polynomial-method-based controller design.