Sami fadali professor ebme university of nevada, reno 1 outline variable structure systems sliding mode control motivating example khalil equivalent control 2 variable structure systems dynamic systems of the form where has discontinuities with respect to some arguments occur in problems in physics, control engineering and mathematics. This control idea may be illustrated by the following example. Variablestructure and constraint control fuela fuelb fc x fc toc onsumesr figure 22. So the structure of the control law varies based on the position of the state trajectory. Lecture notes in control and information sciences, 105, springerverlag, berlin. Pdf variable structure control of systems with nonlinear. Jmz r,a if r0 then jump to a possible forms of conditions and addresses vary. Control systems of variable structure 1976 edition. This paper presents three discretetime variable structure control dvsc methods that can recover those properties for linear uncertain systems.
The statefeedback control law is not a continuous function of time. A tutorial account of variable structure control with sliding mode is presented. To achieve its dynamic decoupling control with high performance and improve the system stability, a sliding mode variable structure smvs control strategy based on inverse system decoupling is proposed. Green abstract a new methodology is presented to improve the design and tuning of a fuzzy logic controller flc using variable structure control vsc theory. In this work multilevel control structures of the column with two products and one feed have been analysed.
A new design approach of the slidingmode variable structure controller basing on the eigenvector of the specific area is presented for the position tracking servo control system in this paper. A variable structure system, or vss, is a discontinuous nonlinear system of the form. Advantageous properties result from changing structures according to this switching logic. Then the adaptive control and variable structure control 14 were proposed, respectively. So the st ru cture of the control law varies based on the position of the state trajectory. Due to the piecewise continuity of these systems, they behave like different continuous nonlinear systems in different regions of their state space. Variable structure con trol vsc is a form of discontinu ous nonlinear con trol. Variables and control structures carleton university. Robust discretetime variable structure control methods. The nonlinear attitude stabilizing control law is solved by variable structure control method.
Variable structure control system design methods are applied to the problem of aircraft spin recovery. Control structures 22 in assembly language, essentially the only control structures are. Application of variable structure control in the nonlinear string. The variable structure control provides a robust and efficient means for the control of nonlinear plants. Pdf digital variable structure control with pseudosliding modes. Variable structure control vsc is used to design the control procedure to suppress the transverse vibration of the axially moving string. Pdf an introduction to sliding mode variable structure control. The method alters the dynamics of a nonlinear system by application of a highfrequency switching control. The control algorithm is stabilizing but through the art of vs with sliding modes.
Sliding mode control design principles and applications to electric drives vadim i. Variable structure control for power systems stabilization. Variable structure control of systems with nonlinear friction. Nonlinear pulse width modulation controller design h.
Adaptive variable structure control of input delay non. A new switching function for variable structure control. This variable structure control law provides an effective and robust means of controlling nonlinear plants. This book reflects the latest developments in variable structure systems vss and sliding mode control smc, highlighting advances in various branches of the vsssmc field, e. Pdf digital design of variable structure control systems. In particular, because variable structure control is suitable for systems that are linear or nonlinear, continual or discrete, certain or uncertain, the application of sliding mode control is regarded as a solution to the problem of improving.
Research on variable structure control law of advanced. Globally stable robust tracking of nonlinear systems using variable structure control and with an application to. Variable structure systems consist of a set of continuous subsystems together with suitable switching logic. The purpose is to introduce in a concise manner the fundamental theory, main results, and practical applications of this powerful control system design approach. During its process it may bifurcate, repeat code or take decisions.
This approach is particularly attractive for the control of nonlinear systems. A numerical simulation for a spacecrafts attitude control system is performed. Prominent characteristics such as invariance, robustness, order reduction. Different design methods are used for systems with matched and mismatched uncertainties. Simple control structures a program is usually not limited to a linear sequence of instructions. Adaptive variable structure of tracking control for. Pdf variable structure control and applications researchgate. Sliding mode vertical strip variable structure control pole assignment smooth control these keywords were added by machine and not by the authors.
Research article adaptive variable structure control of input delay nonminimum phase hypersonic flight vehicles dedong huang1, xiaoxiang hu2 and xunliang yan2 abstract an adaptive variable structure control strategy is proposed for the output tracking control of input delay nonminimum. A bearingless induction motor is a multivariable, nonlinear and strong coupling object. A vsctype rule base is constructed and the fundamentals of flc explored quantitatively by vsc theory. On variable structure control approaches to semiactive control of a quarter car system 5. Sliding mode control design principles and applications to. Design and analysis for this class of systems are surveyed in this paper. Each manipulated variable depends on only a single controlled variable, i. In 17, the authors studied a swarm tracking algorithm via a variable structure approach using arti. Variable structure control for robotics and aerospace. Control of multipleinput, multiple output mimo processes. The chattering of the vsc signal can be reduced by several. At the present time control engineers are interested in the practical implementation of variable structure control.
Advances in variable structure systems and sliding mode. There is a causal relationship between each final element and the controlled variable. Analysis and design communications and control engineering. Variable structure systems and sliding mode state of the art assessment v. Move to the next statement increment the program counter. This process is experimental and the keywords may be updated as the learning algorithm improves. Shewhart control chart for individual measurements. The method alters the dynamics of a nonlinear system by application of a highfrequency sw itching co ntrol. The main argu ments in favor of sliding mode control are order reduction. Lyapunovs second method, as an elegant technique, is used. Variable structure control of a handlaunched glider.
Analysis and design communications and control engineering yan, xinggang, spurgeon, sarah k. The classical state feedback strategy, complemented with the use of state observers, provides a solution. Variable structure control of a pneumatic actuator. Variable structure systems with sliding modes ieee.
Study of integral variable structure control method for. Variable structure control vsc is a wellknown solution to the problem of the deterministic control of uncertain systems since it is with the complete insensitivity to the system variations if parameter variations satisfy certain matching conditions. There is a causal relationship between each final element and the. All the ideas presented in the previous chapters are used here to present a methodology for the integrated design of a control system with multiple controlled variables. Variable structure control vsc has been recognized as a powerful theoretical methodology in applications of the practical control engineering, especially in the. Pdf reachability conditions are developed for discrete singleinputsingle output variable structure control systems described by linear. Variable structure control has been applied to the a variety of flight problems, including 1 control of lateral motion of an aircraft 15, 2 realization of asymptotically decoupled control of roll angle, angle of attack, and sideslip in the presence of rapid maneuvering 1621. Variable structure control vsc is a form of discontinuous nonlinear control. Control structures loops, conditionals, and case statements. In an effort to overcome the nonlinerities associated with a pneumatic system the variable structure control vsc technique has been employed to control the position of a pneumatic actuator. Utkin abstractthe paper deals with the basic concepts, mathemat ics, and design aspects of variable structure systems as well as sliding modes as a principle operation mode. Variable structure and lyapunov control springerlink. A new switching function for variable structure control is proposed in this paper for linear continuoustime systems with uncertainties.
Remember a standard computer only evaluates one instruction at a. In the point view of control the distillation columns can be considered for mimo objects, the control of these kinds of units are a complex task 2. The first method uses a disturbance compensator formulated in the variable structure framework and a decoupling law to separate the disturbance estimation dynamics from the closed loop dynamics. Pdf output feedback variable structure control design. Variable structure control split range is used widely in practice to provide flexibility, retain simple technology and employ simple calculations. Fermentation is known to be a highly nonlinear process and it requires a nonlinear controller for effective control. Variable structure control and applications hindawi. However, the control laws require online calculation of nonlinear functions of the dynamical model, hence, the computational complexity for their implementations is considerably high. However, 16 requires the availability of the acceleration of the leader. The reaching mode phase uses a nonlinear relay control strategy to drive the system trajectory to a predefined switching surface within the motion state space. To accomplish this a model of a pneumatic actuator was developed to allow the control systems to be studied via simulations. An introduction to sliding mode variable structure control.
This book systematizes recent research work on variablestructure control. The state feedback c ontrol law is not a continuous function of time. This paper studies the application of variable structure control or sliding mode control with direct use of nonlinear model to a. Variable structure control of complex systems springerlink. It consists of an ordinary linear term plus an integral term and allows direct use of the pole placement technique. Sliding mode variable structure control strategy of.
Pdf reachability conditions are developed for discrete singleinputsingleoutput variable structure control systems described by linear. The purpose is to introduce in a concise manner the fundamental theory, main. Variable structure control vsc with sliding mode is a special type of control technique that is capable of making a control system robust with respect to system parameter variations and external disturbances. Introduction to vss in recent years much of the research in the area of control theory focused on the design of discontinuous feedback which switches the structure of the system according to the evolution of its state vector. Plsql control structures become a certified professional as part of this plsql tutorial you will learn the control structures in plsql, testing conditions and using the if statement, using case statements, controlling the loop iterations, using the while statements, for loop, sequential control, goto statement and more. There is one controller and more than one final element. It has its roots in relay and bangbang control theory. A variable structure control law typically has two phases of operation. Variable structure control vsc is a viable highspeed switching feedback control for example, the gains in each feedback path switch between two values according to some rule. In these situations there are incentives for considering multivariable control strategies. Variable structure control theory started with the general principles in relays and bangbang control. Comp14051005 variables and control structures fall 2011 402.