Abstract
In this paper, a novel adaptive fault-tolerant controller is proposed for a typical electro-hydraulic rotary actuator in the presence of disturbances, internal leakage fault, and sensor fault simultaneously. To construct the suggested controller, a nonlinear unknown input observer is developed to effectively identify the sensor fault, which is unaffected by not only internal leakage fault but also mismatched disturbances/uncertainties. Furthermore, a radial basis function neural network is designed to compensate for the mismatched disturbances/uncertainties caused by payload variation and unknown friction nonlinearities. Besides, an adaptive law based on the projection mapping function is applied to tackle the effect of the internal leakage fault. The integration of the above-mentioned techniques into the adaptive backstepping terminal sliding mode is investigated to obtain high tracking performance, robustness as well as fast convergence. The stability of the closed-loop system is proven by the Lyapunov theory. Finally, the capability and effectiveness of the proposed approach are validated via simulation results under various faulty scenarios.
Highlights
Nowadays, with the development of modern industrials, the hydraulic actuator has been the most popular and widely used in many applications such as robotic manipulators, ships, aerospace systems
The fault-tolerant controller (FTC) is developed to deal with the impact of faults on the system which can be classified into two main types [15]: sensor fault and actuator fault
The fault detection and identification (FDI) and FTC developments are important to ensure the safety and reliability of the hydraulic control system, especially, in the presence of concerned faults and mismatched disturbances. This approach combines the FTC technique-assisted the fault information of FDI, called active FTC [46], [47]. To overcome these aforementioned drawbacks, in this work, an active FTC is proposed for an electro-hydraulic rotary actuator (EHRA) based on a novel nonlinear unknown input observer (NUIO) and adaptive control laws
Summary
With the development of modern industrials, the hydraulic actuator has been the most popular and widely used in many applications such as robotic manipulators, ships, aerospace systems. The common advantage of those methods is that they provide a valuable and uncomplicated design strategy to preserve an acceptable system performance in presence of sensor faults and with/without disturbances Besides sensor faults, another popular reason affecting control effectiveness is caused by actuator faults, especially the internal leakage fault. The FDI and FTC developments are important to ensure the safety and reliability of the hydraulic control system, especially, in the presence of concerned faults and mismatched disturbances This approach combines the FTC technique-assisted the fault information of FDI, called active FTC [46], [47]. To overcome these aforementioned drawbacks, in this work, an active FTC is proposed for an electro-hydraulic rotary actuator (EHRA) based on a novel NUIO and adaptive control laws.
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