Abstract
This paper presents a fault-tolerant control (FTC) based on impedance control and full state feedback backstepping sliding mode control (FBSMC) algorithm for an n degree of freedoms (n-DOF) serial hydraulic manipulator under the presence of matched and mismatched uncertainties and sensor faults in the constrained framework. These faulty signals, generated from unknown constant or time-variant offset values, happen on both manipulator joint angles and force sensors; thereby degrading the system performance. Therefore, to address both matched and mismatched uncertainties and signal faults, the system dynamics subjects to the sensor faults is mathematically modeled. Then, the robust fault estimation algorithm based on extended state observer (ESO) is proposed to estimate the system state and faulty signals for the FTC design to achieve the force and position tracking performance. System stability of the proposed control scheme is theoretically proven by performing Lyapunov theorems. Finally, comparative simulation results are given on a 3-DOF serial hydraulic manipulator to evaluate the effectiveness of the proposed fault estimation and FTC methodology.
Highlights
As the rapid development in the field of automation, system analysis and control strategy design have become topics of interest in control research area in recent years
Fault-tolerant control (FTC) that combines these observers compensation with advanced control algorithms such as active disturbance rejection control (ADRC) [32], [33], adaptive algorithms [34]–[36], or high robust gains can be employed to address the influence of the actuator fault
Motivated from the above analyses of the favorable control methods, this paper proposes an fault-tolerant control (FTC) for an n-degreeof-freedom (n-DOF) serial hydraulic manipulator under the presence of sensor faults in the constrained framework for the first time
Summary
As the rapid development in the field of automation, system analysis and control strategy design have become topics of interest in control research area in recent years. The sensor faults, in another aspect, can be considered as extended states of the controlled system Other methods, such as using observers or adaptive laws, can be constructed to effectively estimate the magnitude of the faulty signals. Sun et al [47] proposed an adaptive observer to estimate the sensor fault for the active FTC design of linear multi-agent systems. To address the sensor faults effect, and for matched uncertainty, a robust fault estimation based on ESO is proposed to estimate the system state and faulty signal residual. The main contributions of this current work can be listed as 1) To the best of our knowledge, this is the first time the proposed FTC is examined on the hydraulic robotic manipulator subject to constrained framework motion in which both joint angle sensors fault, and force sensor fault are considered.
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