Characteristic model–based adaptive fault-tolerant control for four-PMSM synchronization system

Author(s):  
Yang Gao ◽  
Yifei Wu ◽  
Xiang Wang ◽  
Qingwei Chen

In four-motor servo systems, actuator failures influence control performance seriously through huge inertia ratio changes and unknown disturbances. To solve this problem, an adaptive fault-tolerant control scheme based on characteristic modeling and extended state observer is proposed. First, an adaptive sliding mode observer is designed as fault detection part and offers motor information for controller. Second, to simplify complex dynamic model, this servo system is described by a second-order difference equation. This model integrates uncertainties into three time–varying characteristic parameters to reflect system status. Third, a discrete-time extended state observer is applied to restrain system error caused by actuator failure. Then, a fault-tolerant controller is designed based on characteristic model, and its stability is guaranteed in the sense of Lyapunov stability theorem. These four parts make up the adaptive control scheme and its effectiveness in system control, and fault tolerant is evaluated by both simulation and experiment results.

2021 ◽  
pp. 002029402110286
Author(s):  
Pu Yang ◽  
Peng Liu ◽  
ChenWan Wen ◽  
Huilin Geng

This paper focuses on fast terminal sliding mode fault-tolerant control for a class of n-order nonlinear systems. Firstly, when the actuator fault occurs, the extended state observer (ESO) is used to estimate the lumped uncertainty and its derivative of the system, so that the fault boundary is not needed to know. The convergence of ESO is proved theoretically. Secondly, a new type of fast terminal sliding surface is designed to achieve global fast convergence, non-singular control law and chattering reduction, and the Lyapunov stability criterion is used to prove that the system states converge to the origin of the sliding mode surface in finite time, which ensures the stability of the closed-loop system. Finally, the effectiveness and superiority of the proposed algorithm are verified by two simulation experiments of different order systems.


Author(s):  
Cheng Shuai ◽  
Song Jian

The accumulative electro-hydraulic power steering system (A-EHPS) is essentially an electro-hydraulic servo system with high parametric uncertainties and nonlinearities that are caused by the characteristics of the hydraulic system. The throttle structure in the steering gear and the on-way resistance increase the control difficulty of the plant. This paper reports the construction of a mathematical model that contains the throttle structure and the on-way resistance for the A-EHPS system. Furthermore, an extended state observer and a sliding mode controller are synthesized to estimate uncertain nonlinear components and improve the quality of control in the A-EHPS. The uncertain nonlinear parts contain important information on the high-pressure chamber’s load pressure, which cannot be directly measured. That is, the proposed control scheme can be used to estimate steering resistance, which is essential for the top-layer control strategy. Simulations are performed to validate the control performance and the parameter design principle of the proposed extended state observer scheme. The scheme is then implemented in an actual system, and its robustness advantages over traditional controllers are verified.


Author(s):  
Kejie Gong ◽  
Ying Liao ◽  
Yafei Mei

This article proposed an extended state observer (ESO)–based output feedback control scheme for rigid spacecraft pose tracking without velocity feedback, which accounts for inertial uncertainties, external disturbances, and control input constraints. In this research, the 6-DOF tracking error dynamics is described by the exponential coordinates on SE(3). A novel continuous finite-time ESO is proposed to estimate the velocity information and the compound disturbance, and the estimations are utilized in the control law design. The ESO ensures a finite-time uniform ultimately bounded stability of the observation states, which is proved utilizing the homogeneity method. A non-singular finite-time terminal sliding mode controller based on super-twisting technology is proposed, which would drive spacecraft tracking the desired states. The other two observer-based controllers are also proposed for comparison. The superiorities of the proposed control scheme are demonstrated by theory analyses and numerical simulations.


2021 ◽  
Vol 18 (1) ◽  
pp. 172988142098603
Author(s):  
Daoxiong Gong ◽  
Mengyao Pei ◽  
Rui He ◽  
Jianjun Yu

Pneumatic artificial muscles (PAMs) are expected to play an important role in endowing the advanced robot with the compliant manipulation, which is very important for a robot to coexist and cooperate with humans. However, the strong nonlinear characteristics of PAMs hinder its wide application in robots, and therefore, advanced control algorithms are urgently needed for making the best use of the advantages and bypassing the disadvantages of PAMs. In this article, we propose a full-order sliding mode control extended state observer (fSMC-ESO) algorithm that combines the ESO and the fSMC for a robotic joint actuated by a pair of antagonistic PAMs. The fSMC is employed to eliminate the chattering and to guarantee the finite-time convergence, and the ESO is adopted to observe both the total disturbance and the states of the robot system, so that we can inhibit the disturbance and compensate the nonlinearity efficiently. Both simulations and physical experiments are conducted to validate the proposed method. We suggest that the proposed method can be applied to the robotic systems actuated by PAMs and remarkably improve the performance of the robot system.


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