Certain investigations on design and analysis of loop shaping controller for non linear multivariable system with control challenges using optimization techniques

Abstract

newline The majority of industrial and chemical processes are Multivariable, which means that complex interactions between measurement and control signals are constantly present. Owing to the existence of interactions, Multivariable processes are hard to control and it is challenging to develop a suitable controller for these systems to achieve acceptable performance. The design of a Multivariable control system is in great demand in the process industries. The objective of such controller design is to stabilize the system, track the setpoint, and reject load disturbances in the face of control challenges such as Non-Minimum Phase behavior, model uncertainty, unmeasured disturbances, and constraints on input and output variables. To design a controller for Multivariable processes, classical control structures can be used since they have simple configurations with ease of implementation. However, the controller performances provided by such controllers decay rapidly and are less effective. Thus, controller design must aim at achieving an acceptable trade-off between the conflicting goals of tracking/regulation performance versus robustness to plant uncertainty. This makes it worthwhile investigating the problem of designing controllers for multivariable systems. The robust control of the multivariable system is a vast developing area for designing a control system based on systematically shaping the loop gain of the system to meet performance requirements such as stability margins, robustness metrics, disturbance attenuation. In this research work, Hand#8734; Loop Shaping Control (HILSC), which is one of the robust control methods, has been implemented in the benchmark nonlinear multivariable system, called Quadruple Tank System (QTS). The performance of the QTS with an Hand#8734; Loop Shaping Controller has been established in two different operating conditions namely Minimum Phase and Non-Minimum Phase conditions based on the location of one of its zero. The assessment of the performance of the resultant control system has been exam