Adaptive under-actuated control for capacitive micro-machined ultrasonic transducer based on an accurate nonlinear modeling

Abstract

A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge here is to stabilize the system beyond the pull-in voltage considering imposed perturbations. The CMUT system, on the other hand, has a low range of travel and it is intrinsically unstable, which can result in a pull-in phenomenon. Consequently, in order to use the CMUT systems in a variety of medical applications that require high tuning ratio, a closedloop control technique has been designed for these systems aims at increasing the maximum capacitance and enhancing tunability as well. In this study, using the closed-loop control, the resistance of micro plate against the pull-in phenomenon has been examined. Also, in the description of the system a more accurate nonlinear modeling has been considered in the presence of an under-actuated sliding model control strategy with finite convergence time. Beside, adaptive protocols with unknown upper bounds have been designed to compensate the effects of uncertainty, unmodeled dynamics and external disturbances. The performance of controller in terms of improving output pressure, stabilizing the CMUT and its robustness to imposed perturbations have been investigated. Finally, numerical simulations

Hierarchical sliding mode-based adaptive fuzzy control for uncertain switched under-actuated nonlinear systems with input saturation and dead-zone

“…Under-actuated systems are a kind of important nonlinear systems in which the independent control variables are less than the system degrees of freedom (Zhao et al, 2023a(Zhao et al, , 2023b(Zhao et al, , 2023c(Zhao et al, , 2023dZhang et al, 2022aZhang et al, , 2022bZhang et al, , 2022c, such systems can be found in many areas, such as four rotors rotorcraft (Zemalache et al, 2005), micro-machined ultrasonic transducers (Darbasi et al, 2022), unmanned aerial vehicles (Ullah et al, 2022), etc. In addition, compared with full-actuated systems (Duan, 2021), under-actuated systems are superior in reducing costs, weight and increasing system flexibility.…”