Higher accuracy output feedback sliding mode control of sampled-data systems

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This is the author version of a work accepted for publication in IEEE Transactions on Automatic Control. The definitive version is available via the publisher at 10.1109/TAC.2015.2505303The problem of output feedback sliding mode control for sampled-data systems in the presence of external disturbances is considered. The proposed output feedback control strategy helps obtain a quasi sliding mode with an O(T3) boundary layer, where T is the sampling period. This outperforms the O(T2) result induced by the one-step delayed disturbance approximation method. The proposed scheme is applicable to linear systems which are relative degree one and minimum phase. An example is given to illustrate the efficacy of the new method

A study on high accuracy discrete-time sliding mode control

In this paper a Discrete-Time Sliding-Mode based controller design for high accuracy motion control systems is presented. The controller is designed for a general SISO system with nonlinearity and external disturbance. Closed-Loop behavior of the general system with the proposed control and Lyapunov stability is shown and the error of the closed loop system is proven to be within an o(T2). The proposed controller is applied to a stage driven by a piezo drive that is known to suffer from hysteresis nonlinearity in the control gain. Proposed SMC controller is proven to offer chattering-free motion and rejection of the disturbances represented by hysteresis and the time variation of the piezo drive parameters. As a separate idea 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. Closed-loop experiments are presented using PID controller with and without disturbance compensation and Sliding-Mode Controller with and without disturbance compensation for the purpose of comparison

Evaluation of error bound for a DT sliding mode control with disturbance observer

In this paper an estimate of the upper bound of control error for discrete-time implementation of a Sliding Mode Control (DTSMC) combined with disturbance observer is investigated. Having in mind application to PZT high bandwidth actuators and since high accuracy is required the special attention is paid to avoid chattering. Selected structure of proposed SMC controller is proven to offer chattering-free motion. The proposed structure also avoids deadbeat poles that are the cause of large control action which is not desirable in practical applications. The proposed scheme is shown to allow a maximum error bound of O(T) for the system with disturbance. The main disturbances are represented by hysteresis and the time variation of the piezo stack parameters. The evaluation of the upper bound of error in such a system is shown and experimentally verified. Closed-loop experiments are presented using the proposed method to verify the theoretical results

Experimental investigation of a SMC high precision control

In this paper a discrete-time Sliding-Mode (SM) based controller for high accuracy position control is investigated. The controller is designed for a general SISO system with nonlinearity and external disturbance. It will be shown that application of the proposed controller forces the state trajectory to be within an O(Ts 2). The proposed controller is applied to a stage driven by a piezo drive that is known to suffer from nonlinearity. As a separate idea 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. Closed-loop experiments are presented using PID controller with and without disturbance compensation and Sliding-Mode Controller with and without disturbance compensation for the purpose of comparison

Klizni režimi u diskretnim sustavima upravljanja

The sliding mode application in discrete-time systems can result in unwanted oscillations of the controlled variable (so called chattering). To avoid above-mentioned oscillations a new approach in the design of sliding mode control is proposed in this paper. In the proposed approach the calculation of the equivalent control is not necessary while the influence of the system uncertainty and chattering are reduced. The proposed method is applicable to linear as well as nonlinear systems. It allows the design of the control without transformation of the system description to the discrete-time form (z-domain). Upper bound of the sapling time is determined from the switching function changes during the sampling period. The systems with state observers are analyzed. Experimental and simulation results are presented to clarify the design procedure and the features of the proposed algorithm.Primjena algoritama kliznih režima rada, koji spadaju u grupu algoritama s promjenljivom strukturom upravljanja, može u diskretnim sustavima upravljanja rezultirati neželjenim oscilacijama regulirane varijable. U svrhu spriječavanja ovih oscilacija u radu je predložen jedan novi pristup u sustavu upravljanja s kliznim režimom rada. Predloženim postupkom eliminira se računanje ekvivalentnog upravljanja, smanjuje utjecaj neodređenosti sustava i značajno smanjuju oscilacije izlazne regulirane varijable. Postupak je jednako primjenljiv na linearne i na nelinearne sustave. On omogućuje sintezu sustava bez transformacije u diskretnu formu (z-područje). Gornja granica vrijednosti vremena uzorkovanja određena je iz zahtjeva za ograničenjem promjene funkcije klizanja unutar vremena intervala uzorkovanja. Analiziran je sustav s estimatorom stanja. Kao pokazatelj kvalitete predloženog algoritma prikazani su simulacijski i eksperimentalni rezultati ispitivanja

Klizni režimi u diskretnim sustavima upravljanja

The sliding mode application in discrete-time systems can result in unwanted oscillations of the controlled variable (so called chattering). To avoid above-mentioned oscillations a new approach in the design of sliding mode control is proposed in this paper. In the proposed approach the calculation of the equivalent control is not necessary while the influence of the system uncertainty and chattering are reduced. The proposed method is applicable to linear as well as nonlinear systems. It allows the design of the control without transformation of the system description to the discrete-time form (z-domain). Upper bound of the sapling time is determined from the switching function changes during the sampling period. The systems with state observers are analyzed. Experimental and simulation results are presented to clarify the design procedure and the features of the proposed algorithm.Primjena algoritama kliznih režima rada, koji spadaju u grupu algoritama s promjenljivom strukturom upravljanja, može u diskretnim sustavima upravljanja rezultirati neželjenim oscilacijama regulirane varijable. U svrhu spriječavanja ovih oscilacija u radu je predložen jedan novi pristup u sustavu upravljanja s kliznim režimom rada. Predloženim postupkom eliminira se računanje ekvivalentnog upravljanja, smanjuje utjecaj neodređenosti sustava i značajno smanjuju oscilacije izlazne regulirane varijable. Postupak je jednako primjenljiv na linearne i na nelinearne sustave. On omogućuje sintezu sustava bez transformacije u diskretnu formu (z-područje). Gornja granica vrijednosti vremena uzorkovanja određena je iz zahtjeva za ograničenjem promjene funkcije klizanja unutar vremena intervala uzorkovanja. Analiziran je sustav s estimatorom stanja. Kao pokazatelj kvalitete predloženog algoritma prikazani su simulacijski i eksperimentalni rezultati ispitivanja

An investigation of potential applications of OP-SAPS: Operational Sampled Analog Processors

The application of OP-SAP's (operational sampled analog processors) in pattern recognition system is summarized. Areas investigated include: (1) human face recognition; (2) a high-speed programmable transversal filter system; (3) discrete word (speech) recognition; and (4) a resolution enhancement system