Disturbance observer based adaptive sliding mode controllers for fuzzy systems with mismatched disturbance

Author(s):  
Xiaowei Ma ◽  
Jinhui Zhang ◽  
Ran Huang
2018 ◽  
Vol 41 (1) ◽  
pp. 276-284 ◽  
Author(s):  
Jianguo Guo ◽  
Yuchao Liu ◽  
Jun Zhou

An adaptive sliding mode control (ASMC) approach for a second-order system based on an extended disturbance observer (EDO) is proposed in this paper for systems with mismatched uncertainties. The EDO-based ASMC method is investigated to eliminate the effect of mismatched disturbance by using a novel adaptive sliding surface consisting of the disturbance estimation. The proposed method exhibits the following two attractive features: Firstly, the proposed adaptive sliding mode with disturbance estimation is insensitive to the mismatched disturbance; that is, the asymptotical stability of the adaptive sliding mode can be guaranteed in the presence of the disturbance estimation error of the EDO. Secondly, the chattering in traditional sliding mode control methods is eliminated by using an adaptive term the adaptive parameter. Compared with the disturbance-observer-based sliding mode control and the EDO-based modified sliding mode control method, numerical simulation results and application examples show that the proposed approach is robust, has the best dynamic performance and eliminates chattering.


Author(s):  
Riadh Hmidi ◽  
Ali Ben Brahim ◽  
Slim Dhahri ◽  
Fayçal Ben Hmida ◽  
Anis Sellami

This paper proposes fault-tolerant control design for uncertain nonlinear systems described under Takagi-Sugeno fuzzy systems with local nonlinear models that satisfy the Lipschitz condition. First, by transforming sensor faults as ‘pseudo-actuator’ faults, an adaptive sliding mode observer is designed in order to simultaneously estimate system states, actuator and sensor faults despite the presence of norm-bounded uncertainties. Second, an adaptive sliding mode controller is suggested to provide a solution to stabilize the closed-loop system, even in the event of simultaneous occurrence of faults in actuators and sensors. Next, the main objective of the fault-tolerant control strategy is to compensate for the effects of fault based on the feedback information. Therefore, using the LMI optimization method, sufficient conditions are developed with [Formula: see text] to calculate the gains of the observer and the controller. Then, particular attention is paid to the simultaneous maximization, by convex multi-objective optimization, of the Lipschitz nonlinear constant in Takagi-Sugeno fuzzy modelling and uncertainties attenuation level. The results of the simulation illustrate the effectiveness of our fault-tolerant control approach using a nonlinear inverted pendulum with a cart system.


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