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Variable structure control

About: Variable structure control is a research topic. Over the lifetime, 9637 publications have been published within this topic receiving 190585 citations.


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Journal ArticleDOI
Mark J. Balas1
TL;DR: In this paper, a feedback controller is developed for a finite number of modes of the flexible system and the controllability and observability conditions necessary for successful operation are displayed, and the combined effect of control and observation spillover is shown to lead to potential instabilities in the closed-loop system.
Abstract: Feedback control is developed for the class of flexible systents described by the generalized wave equation with damping. The control force distribution is provided by a number of point force actuators and the system displacements and/or their velocities are measured at various points. A feedback controller is developed for a finite number of modes of the flexible system and the controllability and observability conditions necessary for successful operation are displayed. The control and observation spillover due to the residual (uncontrolled) modes is examined and the combined effect of control and observation spillover is shown to lead to potential instabilities in the closed-loop system. Some remedies for spillover, including a straightforward phase-locked loop prefilter, are suggested to remove the instability mechanism. The concepts of this paper are illustrated by some numerical studies on the feedback control of a simply-supported Euler-Bernoulli beam with a single actuator and sensor.

792 citations

Journal ArticleDOI
TL;DR: In this paper, a multi-input/multi-output adaptive sliding controller is designed and analyzed for the longitudinal dynamics of a generic hypersonic air vehicle, which includes uncertain parameters.
Abstract: A multi-input/multi-output adaptive sliding controller is designed and analyzed for the longitudinal dynamics of a generic hypersonic air vehicle. This vehicle model is nonlinear, multivariable, and unstable and includes uncertain parameters. Simulation studies are conducted for trimmed cruise conditions of 110,000 ft and Mach 15 where the responses of the vehicle to a step change in altitude and airspeed are evaluated. The commands are 100-ft/s step velocity and 2000-ft step altitude. The controller is evaluated for robustness with respect to parameter uncertainties using simulations. Simulation studies demonstrate that the proposed controller is robust with respect to parametric uncertainty and meets the performance requirements with relatively low-amplitude control inputs.

771 citations

Journal ArticleDOI
TL;DR: In this article, the stability of discrete-time sliding mode control systems is investigated and a new sliding mode condition is suggested, and it is shown that the control must have upper and lower bounds.
Abstract: The stability of discrete-time sliding mode control systems is investigated and a new sliding mode condition is suggested. It is shown that the control must have upper and lower bounds. A numerical example is discussed as an illustration.

730 citations

Journal ArticleDOI
TL;DR: In this article, a control-oriented model in closed form is obtained by replacing complex force and moment functions with curve-fitted approximations, neglecting certain weak couplings, and neglecting slower portions of the system dynamics.
Abstract: Full simulation models for flexible air-breathing hypersonic vehicles include intricate couplings between the engine and flight dynamics, along with complex interplay between flexible and rigid modes, resulting in intractable systems for nonlinear control design. In this paper, starting from a high-fidelity model, a control-oriented model in closed form is obtained by replacing complex force and moment functions with curve-fitted approximations, neglecting certain weak couplings, and neglecting slower portions of the system dynamics. The process itself allows an understanding of the system-theoretic properties of the model, and enables the applicability of model-based nonlinear control techniques. Although the focus of this paper is on the development of the control-oriented model, an example of control design based on approximate feedback linearization is provided. Simulation results demonstrate that this technique achieves excellent tracking performance, even in the presence of moderate parameter variations. The fidelity of the truth model is then increased by including additional flexible effects, which render the original control design ineffective. A more elaborate model with an additional actuator is then employed to enhance the control authority of the vehicle, required to compensate for the new flexible effects, and a new design is provided.

696 citations

Journal ArticleDOI
24 Jun 1991
TL;DR: In this article, a large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient.
Abstract: A new large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. One-cycle control rejects power source perturbations in one switching cycle; the average value of the switched variable follows the dynamic reference in one switching cycle; and the controller corrects switching errors in one switching cycle. There is no steady-state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with a constant frequency buck converter have demonstrated the robustness of the control method and verified the theoretical predictions. This new control method is very general and applicable to all types of pulse-width-modulated, resonant-based, or soft-switched switching converters for either voltage or current control in continuous or discontinuous conduction mode. Furthermore, it can be used to control any physical variable or abstract signal that is in the form of a switched variable or can be converted to the form of a switched variable. >

691 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202336
202292
202146
202076
2019105
2018133