In this paper, an adaptive sliding mode tracking control scheme is developed for the medium-scale unmanned autonomous helicopter with system uncertainties and external unknown disturbances. A simplified mathematical model is established, which is divided into position subsystem and attitude subsystem. The uncertainty term of the system is handled by the inherent approximation ability of the neural network. The sliding model control scheme under the backstepping frame is developed for tackling disturbances. The stability of the simplified system is proved by using the Lyapunov theory, and the tracking errors are guaranteed to be uniformly bounded. Numerical simulation results show that the proposed control strategy is effective.
In this paper, we propose an adaptive control approach to deal with the problems of input saturation, external disturbances, and uncertainty in the unmanned autonomous helicopter system. The dynamics of the system take into account the presence of input saturation, uncertainty, and external disturbances. Auxiliary systems are built to handle the input saturation. The neural networks are applied to approximate the uncertain terms. The control scheme combining integral backstepping and sliding mode control is developed in position and attitude subsystems, respectively. In the closed-loop system, the boundedness of the signals is proved by means of the Lyapunov theory. The simulation demonstrates that the approach has good robustness and tracking performance.
The time delay between the changed quantity of the injected fuel and the detection of the resulting change of the air-fuel ratio determines the dynamic nature of the closed-loop control for air-fuel ratio, and the response delay of oxygen sensor itself is a main effect factor. The response characteristics of switching zirconia oxygen sensor will change and even deteriorate with the increasing service time of oxygen sensor. In this paper, the response characteristics of switching zirconia oxygen sensor and the impact of response slowing on air-fuel ratio and emissions are studied through engine bench test, the impact of response delay of switching zirconia oxygen sensor on air-fuel ratio control is analysed, and a new controller of air-fuel ratio based on discrete PI controller is proposed.
Based on fine optical grating and micrometer, one closed-loop high-precision position control system with two modes has been made. The system is used to control the optical elements moving in two ways. That is, one control mode is automatically control with optical grating feedback system and the other mode is manually control with micrometer.Under the support of conservative PID control algorithm, the precision of the system is up to ±0.1ȝm while operating on automatically way, otherwise, the position precision is ±1ȝm.
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