Fault-tolerant control of uncertain Stewart platform under loss of actuator effectiveness

2013 ◽  
Vol 228 (8) ◽  
pp. 1286-1298
Author(s):  
Qiang Meng ◽  
Tao Zhang ◽  
Jing-feng He ◽  
Jing-yan Song ◽  
Chun-yang Yuan
Keyword(s):  
Control Theory ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Stewart Platform ◽  
Parallel Robots ◽  
System Control ◽  
Open Problems ◽  
Model Based ◽  
Control Scheme ◽  
Loss Of Actuator Effectiveness

A novel fault-tolerant control scheme is proposed for the uncertain Stewart platform under loss of actuator effectiveness. The uncertain friction, parameter estimated errors, unmodeled dynamics, and even the unknown actuator faults are analyzed in the controller design, which are open problems in the uncertain nonlinear system control theory and have not been well treated yet. The control torque is computed by the model-based control theory, and subsequently be renewed by compensating the influences of the uncertainties and disturbances based on time delay control scheme. Finally, the novel fault-tolerant controller is derived to extremely reduce the conservativeness and enhance the tracking accuracy. Numerical simulations in the fault-free and faulty conditions are both analyzed to verify the advantages of the proposed control scheme comparing with the model-based controller. Moreover, the proposed control theory can be employed in other parallel robots with a few modifications.

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

2020 ◽  
pp. 095965182095174
Author(s):  
Yang Gao ◽  
Yifei Wu ◽  
Xiang Wang ◽  
Qingwei Chen
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
State Observer ◽  
Extended State Observer ◽  
System Control ◽  
Extended State ◽  
Characteristic Model ◽  
Control Scheme ◽  
Motor Information

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.

Adaptive vector sliding mode fault-tolerant control of the uncertain Stewart platform based on position measurements only

Robotica ◽  
2014 ◽  
Vol 34 (6) ◽  
pp. 1297-1321 ◽  
Author(s):  
Qiang Meng ◽  
Tao Zhang ◽  
Jing-feng He ◽  
Jing-yan Song
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Stewart Platform ◽  
Nonlinear Observer ◽  
Parameter Uncertainties ◽  
Actual System ◽  
Control Scheme ◽  
Adaptive Laws ◽  
Variable Errors

SUMMARYThis paper investigates the trajectory tracking of a Stewart platform, which is a typical multi-input multi-output nonlinear system, with unmodeled dynamics, parameter uncertainties, friction, and unpredictable actuator faults. An adaptive vector sliding mode fault-tolerant control law is derived to ensure the system is insensitive to uncertainties and drive the state variable errors of the closed-loop system to converge to the origin. Moreover, novel adaptive laws are proposed to update the upper boundary of uncertainty according to the actual system state, which greatly reduces the chattering of sliding mode control. Furthermore, velocity signals are estimated by introducing a simple nonlinear observer, resulting in the proposed controller requiring position measurements only. Finally, numerical simulations illustrate the effectiveness of the proposed control scheme.

scholarly journals A Model-based Active Fault Tolerant Control Scheme for a Remotely Operated Vehicle

2018 ◽  
Vol 51 (24) ◽  
pp. 798-805 ◽  
Author(s):  
Alessandro Baldini ◽  
Antonio Fasano ◽  
Riccardo Felicetti ◽  
Alessandro Freddi ◽  
Sauro Longhi ◽  
...  
Keyword(s):  
Active Fault ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Remotely Operated Vehicle ◽  
Model Based ◽  
Control Scheme ◽  
Active Fault Tolerant Control

A fault-tolerant control scheme within adaptive disturbance observer for hypersonic vehicle

2017 ◽  
Vol 233 (3) ◽  
pp. 1071-1088 ◽  
Author(s):  
Jun Zhou ◽  
Jing Chang ◽  
Zongyi Guo
Keyword(s):  
Disturbance Observer ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Lyapunov Theory ◽  
Sliding Mode Controller ◽  
Performance Guarantees ◽  
Uncertain Model ◽  
Control Scheme ◽  
And Performance

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.

Fault tolerant control based on backstepping nonsingular terminal integral sliding mode and impedance control for a lower limb exoskeleton

2021 ◽  
pp. 095440622110357
Author(s):  
Majied Mokhtari ◽  
Mostafa Taghizadeh ◽  
Pegah Ghaf Ghanbari
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Impedance Control ◽  
Fault Tolerant Control ◽  
Integral Type ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Control Scheme

In this paper, an active fault-tolerant control scheme is proposed for a lower limb exoskeleton, based on hybrid backstepping nonsingular fast terminal integral type sliding mode control and impedance control. To increase the robustness of the sliding mode controller and to eliminate the chattering, a nonsingular fast terminal integral type sliding surface is used, which ensures finite time convergence and high tracking accuracy. The backstepping term of this controller guarantees global stability based on Lyapunov stability criterion, and the impedance control reduces the interaction forces between the user and the robot. This controller employs a third order super twisting sliding mode observer for detecting, isolating ad estimating sensor and actuator faults. Motion stability based on zero moment point criterion is achieved by trajectory planning of waist joint. Furthermore, the highest level of stability, minimum error in tracking the desired joint trajectories, minimum interaction force between the user and the robot, and maximum system capability to handle the effect of faults are realized by optimizing the parameters of the desired trajectories, the controller and the observer, using harmony search algorithm. Simulation results for the proposed controller are compared with the results obtained from adaptive nonsingular fast terminal integral type sliding mode control, as well as conventional sliding mode control, which confirm the outperformance of the proposed control scheme.

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