Robust Control Design of a Single Degree-of-Freedom Magnetic Levitation System by Quantitative Feedback Theory

2012 ◽  
Author(s):  
Feng Tian ◽  
Mark Nagurka
Keyword(s):  
Robust Control ◽  
Magnetic Levitation ◽  
Design Method ◽  
Control Design ◽  
Open Loop ◽  
Quantitative Feedback Theory ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Maglev System ◽  
Robust Control Design

A magnetic levitation (maglev) system is inherently nonlinear and open-loop unstable because of the nature of magnetic force. Most controllers for maglev systems are designed based on a nominal linearized model. System variations and uncertainties are not accommodated. The controllers are generally designed to satisfy gain and phase margin specifications, which may not guarantee a bound on the sensitivity. To address these issues, this paper proposes a robust control design method based on Quantitative Feedback Theory (QFT) applied to a single degree-of-freedom (DOF) maglev system. The controller is designed to successfully meet the stability requirement, robustness specifications, and bounds on the sensitivity. Experiments verify that the controller maintains stable levitation even with 100% load variation. Experiments prove that it guarantees the transient response design requirements even with 100% load change and 39% model uncertainties. The QFT control design method discussed in this paper can be applied to other open-loop unstable systems as well as systems with large uncertainties and variations to improve system robustness.

Analytic Loop Shaping Methods in Quantitative Feedback Theory

1994 ◽  
Vol 116 (2) ◽  
pp. 169-177 ◽  
Author(s):  
D. F. Thompson ◽  
O. D. I. Nwokah
Keyword(s):  
Uncertain Systems ◽  
Closed Loop ◽  
Design Method ◽  
Control Design ◽  
Quantitative Feedback Theory ◽  
Single Input Single Output ◽  
Single Output ◽  
Direct Design ◽  
Single Input ◽  
Robust Control Design

Quantitative Feedback Theory (QFT), a robust control design method introduced by Horowitz, has been shown to be useful in many cases of multi-input, multi-output (MIMO) parametrically uncertain systems. Prominent is the capability for direct design to closed-loop frequency response specifications. In this paper, the theory and development of optimization-based algorithms for design of minimum-gain controllers is presented, including an illustrative example. Since MIMO QFT design is reduced to a series of equivalent single-input, single-output (SISO) designs, the emphasis is on the SISO case.

Robust control design of variable speed wind turbine using quantitative feedback theory

2018 ◽  
Vol 232 (6) ◽  
pp. 691-705 ◽  
Author(s):  
Navdeep Singh ◽  
Bhanu Pratap ◽  
Akhilesh Swarup
Keyword(s):  
Robust Control ◽  
Wind Turbine ◽  
Control Design ◽  
Control Technique ◽  
Effective Control ◽  
Quantitative Feedback Theory ◽  
Variable Speed ◽  
Variable Speed Wind Turbine ◽  
Wide Range ◽  
Robust Control Design

A robust control design of a three blade, horizontal axis variable speed wind turbine is developed in this paper. The variable speed wind turbine model consists of higher order nonlinear dynamics where uncertainty has been considered in the plant parameters. Quantitative feedback theory is an effective and efficient, robust control technique through which the desired specifications over a specified range of parametric uncertainty can easily be achieved in the frequency domain. The proposed robust torque and pitch control in variable speed wind turbine using quantitative feedback theory satisfy prescribed gain and phase margin, degree of tracking for the robust performance, fast convergence, noise attenuation, and input and output disturbance rejection. The advantages of the proposed robust control design are the consideration of a wide range of performance specifications and achieving effective control over an increased operating frequency range. The simulation results demonstrate the satisfactory performance of proposed quantitative feedback theory-based controller and prefilter which fulfill the necessary conditions such as robust stability and robust tracking. Further, it has been shown that the performance of the quantitative feedback theory-based controller is better than the performance with a standard wind turbine controller and also from the performance by proportional-integral controller.

A New Robust Control Design for Linear Systems With Norm Bounded Time Varying Real Parameter Uncertainty

2010 ◽  
Author(s):  
Nagini Devarakonda ◽  
Rama K. Yedavalli
Keyword(s):  
Robust Control ◽  
Linear Systems ◽  
Parameter Uncertainty ◽  
Design Method ◽  
Control Design ◽  
Design Methods ◽  
Real Parameter ◽  
Time Varying ◽  
Robust Control Design ◽  
Real Parameter Uncertainty

In this paper, a new methodology for robust control design of linear systems with time varying real parameter uncertainty is presented. The distinctive feature of this method is that it specifically offers robustness guarantees to real parameter uncertainty thereby providing a much needed alternative design method compared to existing design methods such as H∞ and μ-synthesis methods which tend to be conservative when specialized to real parameter uncertainty. The proposed robust control design method is inspired by sign (qualitative) stability idea from ecology, leading to a specific structure in the desired closed loop system matrix involving pseudosymmetry. The design procedure is simple and straightforward without requiring intensive computation. The proposed design algorithm is illustrated with aerospace applications. This algorithm is quite promising with considerable scope for extensions and improvements, finally adding to the bank of available control design methods for linear state space systems.

scholarly journals Robust Additive Manufacturing Performance through a Control Oriented Digital Twin

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 708
Author(s):  
Panagiotis Stavropoulos ◽  
Alexios Papacharalampopoulos ◽  
Christos K. Michail ◽  
George Chryssolouris
Keyword(s):  
Additive Manufacturing ◽  
Process Control ◽  
Design Method ◽  
Control Design ◽  
Open Loop ◽  
Linear Matrix ◽  
Loop Model ◽  
Digital Twin ◽  
Manufacturing Process Control ◽  
Robust Control Design

The additive manufacturing process control utilizing digital twins is an emerging issue. However, robustness in process performance is still an open aspect, due to uncertainties, e.g., in material properties. To this end, in this work, a digital twin offering uncertainty management and robust process control is designed and implemented. As a process control design method, the Linear Matrix Inequalities are adopted. Within specific uncertainty limits, the performance of the process is proven to be acceptably constant, thus achieving robust additive manufacturing. Variations of the control law are also investigated, in order for the applicability of the control to be demonstrated in different machine architectures. The comparison of proposed controllers is done against a fine-tuned conventional proportional–integral–derivative (PID) and the initial open-loop model for metals manufacturing. As expected, the robust control design achieved a 68% faster response in the settling time metric, while a well-calibrated PID only achieved 38% compared to the initial model.

Sign in / Sign up

Export Citation Format

Share Document