Asif Sabanovic

Variable Structure Systems With Sliding Modes in Motion Control—A Survey

This paper presents a comprehensive overview of the application of Variable Structure Systems (VSSs) with Sliding Mode (SM) methods in motion control systems. Our aim is to give implementable sliding mode design solutions for complex motion systems, actuators and supply converters. This paper provides a frame for further study of sliding mode applications in motion control systems.

Variable structure systems: from principles to implementation

* Part I: Sliding mode control theory * Chapter 1: Sliding mode control * Chapter 2: Sliding mode regulator design * Chapter 3: Deterministic output noise effects in sliding mode observation * Chapter 4: Stochastic output noise effects in sliding mode observation * Part II: New trends in sliding mode control * Chapter 5: Discrete-time VSS * Chapter 6: Robustness issues of 2-sliding mode control * Chapter 7: Sliding modes, delta-modulation and output feedback control of dynamic systems * Chapter 8: Analysis of sliding modes in the frequency domain * Chapter 9: Output tracking in causal nonminimum-phase systems using sliding modes * Part III: Applications of sliding mode control * Chapter 10: Sliding mode control and chaos * Chapter 11: Sliding modes in fuzzy and neural network systems * Chapter 12: SMC applications in power electronics * Chapter 13: Sliding modes in motion control systems * Chapter 14: Sliding mode control for automobile applications * Chapter 15: The application of sliding mode control algorithms to a diesel generator set * Chapter 16: Motion control of underwater objects by using second order sliding mode techniques * Chapter 17: Semiglobal stabilisation of linear uncertain system via delayed relay control

Sliding mode control of AC drives

The application of sliding mode control to permanent-magnet synchronous motors (DC brushless motors), wound-rotor synchronous motors, and asynchronous motors is presented. A unified approach to the control problem of AC machines reveals that a simple control algorithm which effectively solves the problem can be derived using variable-structure system theory. Selection of the control variable (angular position, speed, acceleration, or torque) leaves the basic control structure unchanged, and even current limiting can easily be included. The theoretical results are verified by experiments. The design procedure and experimental results show that this approach provides good behavior of the system in both transient and steady-state operation. >

A study on robustness property of sliding-mode controllers: a novel design and experimental investigations

The robustness property of sliding-mode controllers (SMCs) makes them attractive for industrial control applications. However, this property is valid only under ideal sliding-mode conditions. Additionally, practical SMCs are likely to exhibit high-frequency oscillations in the plant output, called chattering, and to excite unmodeled dynamics. A novel, chattering-free sliding-mode control algorithm design, based on Lyapunov stability criteria, is considered in this paper. The control algorithm developed is experimentally implemented on a direct-drive manipulator for various payload configurations. It is seen that the controller carries a certain amount of robustness property, the trajectory-following performance being only slightly affected by the changes in the payload. A comparison of the experimental results with those obtained by a well-tuned proportional-derivative control is also given.

SMC With Disturbance Observer for a Linear Belt Drive

Accurate position-tracking control in a belt-driven servomechanism can experience vibrations and large tracking errors due to compliance and elasticity introduced by force transmission through the belt and nonlinear-friction phenomenon. In this paper, a new control algorithm which is based on a sliding-mode control that is able to deal with these problems is proposed. In order to further optimize position-tracking performance, the control scheme has been extended by an asymptotic disturbance observer. It has been proven that robust and vibration-free operation of a linear-belt-driven system can be achieved. The experiments presented in this paper show improved position-tracking error response while maintaining vibration suppression.

Sliding-Mode Control for High-Precision Motion of a Piezostage

In this paper, control of piezostage using sliding-mode control (SMC) method is presented. Due to the fast dynamics of the piezostage and since high accuracy is required the special attention is paid to avoid chattering. The presence of hysteresis characteristics represents main nonlinearity in the system. Structure of proposed SMC controller is proven to offer chattering-free motion and rejection of the disturbances represented by hysteresis and the time variation of the piezostack parameters. In order to enhance the accuracy of the closed loop system, a combination of disturbance rejection method and the SMC controller is explored and its effectiveness is experimentally demonstrated. The disturbance observer is constructed using a second-order lumped parameter model of the piezostage and is based on SMC framework. Closed-loop experiments are presented using a proportional-integral-derivative controller and sliding-mode controller with disturbance compensation for the purpose of comparison

Sliding-Mode Neuro-Controller for Uncertain Systems

In this paper, a method that allows for the merger of the good features of sliding-mode control and neural network (NN) design is presented. Design is performed by applying an NN to minimize the cost function that is selected to depend on the distance from the sliding-mode manifold, thus providing that the NN controller enforces sliding-mode motion in a closed-loop system. It has been proven that the selected cost function has no local minima in controller parameter space, so under certain conditions, selection of the NN weights guarantees that the global minimum is reached, and then the sliding-mode conditions are satisfied; thus, closed-loop motion is robust against parameter changes and disturbances. For controller design, the system states and the nominal value of the control input matrix are used. The design for both multiple-input-multiple-output and single-input-single-output systems is discussed. Due to the structure of the (M)ADALINE network used in control calculation, the proposed algorithm can also be interpreted as a sliding-mode-based control parameter adaptation scheme. The controller performance is verified by experimental results

Sliding modes in power electronics and motion control systems

In this paper the concepts, design aspects and application of Sliding Mode Control (SMC) systems to power electronics and motion control systems are discussed. The salient features of the Variable Structure Systems (VSS) with sliding modes are order reduction, decoupling in the design procedure, insensitivity in plant parameter changes and disturbances rejection. Simple implementation makes concepts of SMC very attractive in power electronics and motion control systems. Application to problems like control of DC and AC converters, the control of electrical machines and the design of the observers for electrical machines are discussed.

Improved design of VSS controller for a linear belt-driven servomechanism

This paper proposes a new control algorithm for a linear belt-driven servomechanism. The elasticity of the belt and large nonlinear friction along with large variation of parameters limit the applicability of the belt driven servosystems. Design of simple control that can guarantee stable, vibration-free operation for large variation of load is needed to extend application of such a linear stage. The proposed control is based on the application of sliding mode methods combined with Lyapunov design so it guarantees the stability of the system. Due to the restriction of the system motion to specially selected sliding mode manifold the vibration free position tracking is achieved with very good disturbance rejection. Proposed algorithm is simple and practical for an implementation and the tuning procedure of the control parameters is simple. The experiments have shown that the proposed control scheme effectively suppresses vibrations and assures wide closed-loop bandwidth for position tracking control.

A Controller Design Method Based on Functionality

Robots are expected to expand their range of activities to human environment. Robots in human environment need redundancy for environmental adaptation. Furthermore, they have to automatically modify their controllers in response to varying conditions of the environment. Therefore, the authors have proposed a method to design a hyper-degrees-of-freedom (DOF) control system efficiently. The method decouples a large control system into small independent components called ldquofunction.rdquo Motion of the entire control system is expressed as superposition of multiple functions. Combination of some functions realizes many patterns of motion. Hence, various motions are realized with much smaller efforts on controller design. Additionally, the controller design is explicit since a controller and a function correspond directly. This paper expands the method to multi-DOF robots in 3-D space, since the conventional method was limited to a multirobot system in 1-D space. A new problem of interference among function-based systems occurs along with the expansion. A disturbance observer is applied on each actuator to eliminate the interference. Procedures of controller design under varying conditions are also shown. The proposed method is applied to a grasping manipulator with 18 DOF. Its experimental results show the validity of the method.