TABLE OF CONTENTS Because the implementation of modern controllers is usually based on the use of a computer or digital signal processor, the next few chapters are devoted to the problem of digital controller design for continuous nonlinear time-varying systems. In particular, in this chapter, the design of digital controllers based on the so-called pseudo-continuous approach is presented, where the digital controller is the result of continuous-time controller discretization. The continuous-time controller with the relative highest output derivatives in feedback is used, and the effect of discretization at discrete time instants has been taken into account by inclusion of a zero-order hold (ZOH) transfer function. A distinguishing feature of the approach is that a pseudo-continuous-time model of the control loop with a pure time delay is used, where the pure delay is a result of the ZOH transfer function approximation. Finally, a control law with compensation of the pure time delay is presented, which allows us to increase the sampling period.
This chapter is concerned with the control system shown in Fig. 10.1. Here the continuous system is preceded by a digital-analog converter (DAC), and the output is sampled by an analog-digital converter (ADC). Note that the output signals of the DAC and ADC are to be taken as sampled-data signals; that is, the effect of the sampling process at discrete time instants is taken into account, while the quantization of signals in amplitude is not discussed. Assume that the continuous-time system is...
