“Digital PID controller design for multivariable analogue systems with computational input-delay,” IMA Journal of Mathematical Control and Information, Vol.21, pp 433–456, 2004.
This paper presents a new methodology to design MIMO digital PID controllers for multivariable analogue systems with computational input time-delay. The preliminarily designed analogue PID controller is refined using a newly developed state-feedback and state-feedforward LQR approach. The optimally designed closed-loop system with the refined MIMO analogue PID controller has pre-assigned closed-loop eigenvalues. A prediction-based digital redesign technique is developed to discretize the cascaded MIMO analogue PID controller, such that the states of the digitally redesigned closed-loop sampled-data system with the MIMO digital PID controller are close to those of the analogously designed closed-loop system with the refined MIMO analogue PID controller. The aforementioned digital redesign technique is further modified based on the predictive control method to cope with MIMO analogue systems with input delay.