Normalized decoupling control for high-dimensional MIMO processes for application in room temperature control HVAC systems

A novel decoupling control system design for high-dimensional multi-input, multi-output (MIMO) processes is presented. Based on the Relative Normalized Gain Array (RNGA), an Equivalent Transfer Function (ETF) for each element in the transfer function matrix was derived for the closed-loop control system and was used to approximate the inverse of the process transfer function matrix. The decoupler could be easily determined with each element in the First-Order-plus-Time-Delay (FOPTD) form and resulted in a stable, proper and causal decoupled matrix. A PI/PID controller could then be designed to meet the performance objectives. The main advantage of this method was its simplicity; it did not require extensive calculation effort. To demonstrate its effectiveness, the decoupling control strategy was applied to control the temperatures of four neighboring rooms in an HVAC process.