A novel sliding mode control (SMC) method for indirect current controlled three-phase parallel active power filter is presented in this paper. There are two designed closed loops in the system: one is the DC voltage controlling loop and the other is the reference current tracking loop. The first loop with a PI regulator is used to control the DC voltage approximating to the given voltage of capacitor, and the output of PI regulator through a low-pass filter is applied as the input of the power supply reference currents. The second loop implements the tracking of the reference currents using integral sliding mode controller, which can improve the harmonic treating performance. Compared with the direct current control technique, it is convenient to be implemented with digital signal processing system because of simpler system structure and better harmonic treating property. Simulation results verify that the generated reference currents have the same amplitude with the load currents, demonstrating the superior harmonic compensating effects with the proposed shunt active power filter compared with the hysteresis method.

In this paper, an adaptive fuzzy sliding mode control strategy with bound estimation is proposed to control the position of a micro-electro-mechanical systems gyroscope in the presence of model uncertainties and external disturbances. The proposed adaptive fuzzy sliding mode control system is composed of a fuzzy controller and a sliding mode controller. The sliding controller is designed to compensate for the approximation error between fuzzy controller and optimal fuzzy control law. The adaptation laws based on the Lyapunov analysis can adaptively adjust the fuzzy rules, thus guaranteeing the stability of the closed loop adaptive fuzzy control system. Moreover, an estimation mechanism is derived to identify the unknown upper bound of approximation error. Numerical simulations are investigated to verify the effectiveness of the proposed adaptive fuzzy control scheme.

In the practical control of microelectromechanical system (MEMS) gyroscopes, dead-zone non-linearity often exists, which has negative influence on the resolution and performance of the gyroscope system. System non-linearities are inevitable in actual MEMS gyroscopes and require the controller to be either adaptive or robust to these non-linearities. In this paper, an adaptive fuzzy compensator is designed to compensate the dead-zone non-linearities for MEMS gyroscope. A fuzzy logic system is used for dead-zone non-linear switching function and an optimal algorithm is designed to make the dead-zone compensator to tune the parameters adaptively. The closed-loop stability can be guaranteed with the proposed adaptive fuzzy dead-zone compensation. Simulation results demonstrate that the tracking error can be attenuated efficiently and robustness of the control system can be improved with the proposed adaptive fuzzy non-linearity compensator.

In this paper, a direct adaptive fuzzy control using a supervisory compensator is designed for the robust tracking of a MEMS gyroscope sensor. The parameters of the membership functions are adjusted according to the designed adaptive law for the purpose of tracking a reference trajectory. A fuzzy controller that can approximate the unknown nonlinear function and compensate the system's nonlinearities is incorporated into the adaptive control scheme in the Lyapunov framework. A supervisory compensator is adopted to guarantee the stability of the closed loop system. Numerical simulations for a MEMS angular velocity sensor are investigated in order to verify the effectiveness of the proposed adaptive fuzzy control scheme and show that the system using the designed fuzzy controller with a supervisory compensator has better tracking performance and robustness than that using only a fuzzy control without a supervisory compensator in the presence of external disturbances.

An adaptive H-infinity tracking control is proposed for a z-axis microgyroscope with system nonlinearities. All the signals can be guaranteed in a bounded range, and tracking error is uniformly ultimately bounded, an H-infinity tracking performance is also achieved to a prescribed level. Adaptive control methodology is integrated with H-infinity control technique to achieve robust adaptive control, and adaptive algorithm is used to estimate the unknown system parameters. Simulation studies for microgyroscope are conducted to prove the validity of the proposed control scheme with good performance and robustness.