Digital controller design for dynamic systems with arbitrary output delay

In this paper, the digital state space representation of dynamic systems with arbitrary output delay is presented. The technique utilized is the zero order hold (ZOH) equivalent of the dynamic system. The representation is then utilized to obtain a rational Z-domain representation of such systems. The concept of the modified Z-transform used earlier for input type of delays is extended to output delays of arbitrary length. All the standard techniques of linear system design such as the frequency response, root-locus, and PID compensator, etc. can be applied for the digital controller design without approximating the delay to be integer multiple of the sampling period. In addition, technique for digital controller design using the estimator-controller method is provided. This method of controller design can be used for accurate system modeling and control of tape and disk drive systems where the calculation and measurement delays are deterministic in nature. Finally, examples are provided to illustrate the design techniques.