In this paper, a novel adaptive fault-tolerant controller is proposed for a typical electrohydraulic 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.

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Over the past few years, triboelectric nanogenerators (TENGs) have emerged as promising devices for energy harvesting and self-powered sensing owing to their miniaturized structural design, lack of material limitation, high stability, and ecofriendly nature. In this study, the membrane consisting of poly(vinylidene fluorideco-hexafluoropropylene) (PVDF-HFP) and ionic liquid (PIL) is fabricated as triboelectric material, namely PIL membrane. To further improve the hydrophobicity of the membrane and the output performance of the TENG, different PIL membranes are prepared using various IL concentrations and their structures are modified using the evaporation phase inversion technique. The PIL membranes with nanoporous structures and strong hydrophobicity are synthesized by blade coating and bent to generate circular tube shapes for use in PIL-TENG cells. Therefore, the PIL-TENG has a high output performance owing to the availability of more ions through the establishment of an electrical double layer and an increase in electronegativity properties by doping with more fluoride atoms. Under optimal conditions, a nanoporous PIL-TENG of 10 wt.% ionic liquid exhibited the maximum peak-to-peak with an output voltage of 16.95 V and current of 2.56 μA. Especially, the instantaneous peak power density of the PIL-TENG reached the highest value of 26.1 mW/m 2 , which was 212% higher than that of the pristine PVDF-HFP TENG (P-TENG). In this manner, a new material for the triboelectric layer is presented to effectively improve the output performance, stability, and durability of TENGs, which are promising for use in practical applications related to harvesting hydrokinetic energy, self-powered sensors, and other applications.