Force control of an uncertain series elastic actuator system via a fuzzy sliding mode controller and a nonlinear state estimator

Author(s):  
Seyed Ali Moafi ◽  
Farid Najafi

Nowadays, series elastic actuators play an important role in actuation technology, especially for mechatronics and robotic applications. In this article, the accurate tracking of output force for a series elastic actuator is investigated. In order to achieve this aim, a novel robust control scheme is developed to overcome friction effects, backlash in the drivetrain, measurement noises (sensor inaccuracy) and uncertainties in the dynamic model. The control scheme consists of a fuzzy sliding mode controller and a nonlinear state estimator. The theory of Lyapunov stability is used for the formulation of the proposed controller and also the fuzzy logic strategy is used for tuning the sliding surface parameter in order to achieve accurate and chattering-free performance. Furthermore, a powerful estimator algorithm, unscented H-infinity filter, is added to the control scheme to improve the robustness of the system. Simulation results, as well as experimental analysis, approved the efficiency of the proposed approach in the presence of uncertainties and disturbances.

2013 ◽  
Vol 427-429 ◽  
pp. 1179-1182
Author(s):  
Sheng Bin Hu ◽  
Jin Yuan Xu ◽  
Xuan Wu ◽  
Chi Zhang ◽  
Yi Hao He

A fast terminal fuzzy sliding mode control scheme for the attitude of flapping wing micro aerial vehicle is proposed in this paper. Based on the feedback linearization technique, a fast terminal sliding mode controller is designed. To diminish the chattering in the control input, a fuzzy controller is designed to adjust the generalized gain of fast terminal fuzzy sliding mode controller according to fast terminal sliding mode surface. The stability of the control algorithm is verified by using Lyapunov theory. Simulation results show that the proposed control scheme is effective.


Author(s):  
Seyed Ali Moafi ◽  
Farid Najafi

This paper proposes a robust control scheme to accomplish the interaction control problem between a series elastic actuator (SEA) and a flexible environment. The adaptability of the controller to unknown variations and robustness of the controller during interaction of the system with environment are the main aims. The control scheme is based on a fuzzy impedance control approach and consists of an inner fast terminal sliding mode force control loop. An experimental setup is designed to prove the efficiency of the developed controller. The experimental results confirm that the proposed fuzzy logic controller guarantees the sensitivity of the controlled system to unpredictable variations. Moreover, by applying the fast terminal sliding mode algorithm for the inner force control loop, the system has faster convergence to the reference path compared with similar control methods found in the literature.


2011 ◽  
Vol 105-107 ◽  
pp. 2213-2216 ◽  
Author(s):  
Sheng Bin Hu ◽  
Min Xun Lu

To achieve the tracing control of a three-links spatial robot, a backstepping fuzzy sliding mode controller based on variable rate reaching law is proposed in this paper. The sliding mode controller is designed by means of backstepping way. To reduce the adjustment time, a fuzzy controller is designed to adjust the slope of sliding mode surface. To diminish the chattering of traditional sliding mode control, the variable rate reaching law is proposed. The variable rate reaching law is composed of the distance from current point to sliding mode surface in phase plane. The simulation studies for the tracking control of a three-links spatial robot have been carried out. Simulation results show the validity of the proposed control scheme.


2009 ◽  
Vol 23 (16) ◽  
pp. 2021-2034 ◽  
Author(s):  
XINGYUAN WANG ◽  
DA LIN ◽  
ZHANJIE WANG

In this paper, control of the uncertain multi-scroll critical chaotic system is studied. According to variable structure control theory, we design the sliding mode controller of the uncertain multi-scroll critical chaotic system, which contains sector nonlinearity and dead zone inputs. For an arbitrarily given equilibrium point of the uncertain multi-scroll chaotic system, we achieve global stabilization for the equilibrium points. Particularly, a class of proportional integral (PI) switching surface is introduced for determining the convergence rate. Furthermore, the proposed control scheme can be extended to complex multi-scroll networks. Finally, simulation results are presented to demonstrate the effectiveness of the proposed control scheme.


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