Approximate Models in Multivariable Process Control: An Inverse Nyquist Array and Robust Tuning Regulator Interpretation

Using the widely accepted philosophy that simple control design procedures are of great value in producing acceptable controllers for plant with a degree of dynamic and/or structural simplicity, particularly in the situation where closed-loop performance requirements are modest, recent work on the use of approximate models and plant step data in multivariable design is applied to produce simple, robust design algorithms for process plant which, in the presence of suitable precompensation, has "small" interaction effects and/or simple loop dynamics that can be approximated by delay-lag models.