State and Extended Disturbance Observer for Sliding Mode Control of Mismatched Uncertain Systems

Author(s):  
Divyesh Ginoya ◽  
P. D. Shendge ◽  
S. B. Phadke

In this paper, a state and extended disturbance observer (DO) is designed for mismatched uncertain systems. Apart from system states and disturbances, the proposed observer estimates the derivatives of the disturbances and thereby improves the accuracy of estimation of disturbances as well as the states. No knowledge of bounds of disturbances or their derivatives is assumed. An observer–controller combination for a sliding mode controller that requires the estimates of the derivatives of disturbances is described, and the ultimate boundedness of the overall system is proved. The proposed observer is illustrated by simulation of a numerical example and a rotary hydraulic actuator. The proposed observer–controller combination is validated on a serial flexible joint manipulator in laboratory.

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Wenru Fan ◽  
Bailing Tian

A multivariable super-twisting sliding mode controller and disturbance observer with gain adaptation, chattering reduction, and finite time convergence are proposed for a generic hypersonic vehicle where the boundary of aerodynamic uncertainties exists but is unknown. Firstly, an input-output linearization model is constructed for the purpose of controller design. Then, the sliding manifold is designed based on the homogeneity theory. Furthermore, an integrated adaptive multivariable super-twisting sliding mode controller and disturbance observer are designed in order to achieve the tracking for step changes in velocity and altitude. Finally, some simulation results are provided to verify the effectiveness of the proposed method.


Author(s):  
Jun Zhou ◽  
Jing Chang ◽  
Zongyi Guo

The paper describes the design of a fault-tolerant control scheme for an uncertain model of a hypersonic reentry vehicle subject to actuator faults. In order to improve superior transient performances for state tracking, the proposed method relies on a back-stepping sliding mode controller combined with an adaptive disturbance observer and a reference vector generator. This structure allows for a faster response and reduces the overshoots compared to linear conventional disturbance observers based sliding mode controller. Robust stability and performance guarantees of the overall closed-loop system are obtained using Lyapunov theory. Finally, numerical simulations results illustrate the effectiveness of the proposed technique.


2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881527 ◽  
Author(s):  
Xudong Liu ◽  
Ke Li

A novel speed control method based on sliding mode control and disturbance observer is studied for permanent magnet synchronous motor drives. Different from the conventional speed and current cascade control structure in the field-oriented vector control, the new controller adopts the single-loop control structure, in which the speed and quadrate axes current controllers are combined together. First, a multiple-surface sliding mode controller is designed for the speed control system of permanent magnet synchronous motor. Although the sliding mode controller has the strong robustness for the matched disturbance in the system, it still cannot deal with mismatched disturbance effectively, such as external load disturbance and some parameter variations. Thus, the disturbance observer is introduced to estimate the disturbance in the motor, which is designed by combining the proposed sliding mode controller. Finally, the effectiveness is tested under various conditions by both simulation and experiment. The results show that the designed controller has the fast transient response and robustness under different operating conditions.


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