Decentralized Controller Design and Gain Tuning Approach for MIMO Systems: Application to Reel-to-Reel Systems

Multi-input multi-output (MIMO) control systems are common in many industrial applications, such as reel-to-reel (R2R) systems, process control in distillation columns, robotic manipulators, and flight control. The coupling between plant inputs and outputs makes controller design challenging, especially when selecting controller gains in transfer function-based approach. This paper proposes a simple yet practical method for designing the controller using a decentralized approach based on transfer functions, along with an intuitive gain-tuning procedure. Unlike state-of-the-art methods, this approach does not require solving complex optimization problems. It is also generalizable to any MIMO control system. The controller design approach simplifies the MIMO system by shaping the open-loop transfer function into a triangular form, allowing it to be treated as a set of individual SISO systems. Each SISO system is influenced by a specific level of internal disturbance. These disturbances are associated with the dynamics of the actuators controlling the control variables, and therefore can be modeled based on the knowledge of the actuator dynamics. This makes controller design and gain tuning simpler compared to the complex algorithms used in the literature. The effectiveness of the proposed approach is demonstrated by its implementation on a $2\times 2$ R2R system hardware. Finally, the stability and robustness of the designed control system are experimentally assessed and various stability margins are obtained.