PID control of TITO systems

Abstract: This thesis treats controller design and tuning for systems with two input signals and two output signals in the process industry. Two design methods that can be combined to form a core in an algorithm for automatic design and tuning for the considered systems are presented. The proposed controller consists of a decoupler and a diagonal PID controller. This implies that the two main problems to solve are those of how to design the decoupler and how to design the diagonal controller. The decoupling problem is treated in a general way in this thesis and a decoupler design method is proposed. A PID controller design method is also proposed. The method is based on exhaustive search, and a simple version of software for this is presented. The methods are combined and tested in both simulations and on a real process in an industrial environment.