The paper presents some approaches for the design of a diagonal Propor
tional-Integral-Derivative (PID) controller for a two-input two-output
TITO) system. First, a new autotuning procedure is given for a TITO s
ystem and from the results of this a design method is developed based
on moving the critical point to a desired position on the compensated
characteristic loci. Second, an optimisation method using integral per
formance criteria is presented. Examples are given to illustrate both
design methods.