Robust fractional-order auto-tuning for highly-coupled MIMO systems

Abstract

Many processes in industry are highly-coupled Multiple-Input Multiple-Output (MIMO) systems. In this paper, a methodology, based on the Kissing Circle (KC) tuning method, is proposed to tune a fractional-order PI controller for these types of systems. The KC method relies on frequency domain specifications and emphasizes improving robustness. The method does not require a model, a single sine test suffices to obtain the controller parameters. Hence, the method can be categorized as an auto-tuner. For comparison, an integer-order PI is tuned with the same requirements. To evaluate and analyze the performance of both controllers an experimental test bench is used, i.e. a landscape office lighting system. A direct low-order discretization method is used to implement the controller in a real process. Both controllers are subjected to simulation experiments to test the performance in time and frequency domain and they are subjected to process variations to evaluate their robustness. The fractional controller manages to control a process that is susceptible to 85% variation in time constant mismatch as opposed to 79% for the integer-order controller. An Integer Absolute Error evaluation of experimental results show that the fractional-order PI controller and integer-order PI controller have similar control performance, as expected from the frequency domain analysis. As model uncertainty can add up in MIMO systems, improved robustness is crucial and with this methodology the control performance does not deteriorate. Moreover, a decrease in power consumption of 6% is observed.

The Application of a New PID Autotuning Method for the Steam/Water Loop in Large Scale Ships

“…In this section, the theory of the KC autotuning method is introduced in detail [39][40][41][42]. The main idea of the KC autotuner is shown in Figure 2.…”

Design and Implementation of Novel Fractional-Order Controllers for Stabilized Platforms

“…I. Birs [19] focus on general tuning procedures, especially for the fractional order proportional integral derivative controller. J. Juchem [20] proposed a tuning methodology of fractionalorder PI controller based on the Kissing Circle(KC) method for those systems which are highly-coupled and Multiple-Input Multiple-Output(MIMO). Z. Bingul [21] studied the performance of FOPID controller and evolutionary algorithm in robot trajectory control.…”

Ergonomic and Economic Office Light Level Control

“…Previous attempts to regulate light levels in office landscape areas have provided solutions based on PID control and generalized order PID-type controllers, with successful performance in terms of reference setpoint tracking [8,9]. In addition, a large number of applications have made use of lighting control techniques, such as conventional methods, implementations of intelligent techniques, and agent-based controllers [10], taking into consideration the features of the environment.…”