On the basis of the classical computed torque control method, a new composite nonlinear feedback design method for robot manipulators with uncertainty is presented. The resulting controller consists of the composite nonlinear feedback control and robust control. The core is to use the robust control for online approximation of the system’s uncertainty as a compensation term for the composite nonlinear feedback controller. The design method of the new controller is given, and the convergence of the closed-loop system is proved. The simulation results show that the proposed scheme can make the uncertain robot system have strong robustness and anti-interference ability.
An adaptive optics (AO) system with Stochastic Parallel Gradient Descent (SPGD) algorithm and a 61-element deformable mirror is simulated to restore the image of a turbulence-degraded extended object. SPGD is used to search the optimum voltages for the actuators of the deformable mirror. We try to find a convenient image performance metric, which is needed by SPGD, merely from a gray level distorted image and without any additional optics elements. Simulation results show the gray level variance function acts more promising than other metrics, such as metrics based on the gray level gradient of each pixel. The restoration capability of the AO system is investigated with different images and different turbulence strength wave-front aberrations using SPGD with the above resultant image quality criterion. Numerical simulation results verify the performance metric is effective and the AO system can restore those images degraded by different turbulence strengths successfully.
This article focuses on realizing the chaos control of a permanent magnet synchronous motor by combining a pseudo-linear inverse system of the permanent magnet synchronous motor and synthetical sliding mode control. First, the permanent magnet synchronous motor dimensionless nonlinear mathematical model is established, and its chaos is analyzed by the Lyapunov exponent method. The permanent magnet synchronous motor parameter range when chaos appears is obtained. Then, the inverse system decoupling method is used to analyze the reversibility of the permanent magnet synchronous motor system, and the permanent magnet synchronous motor inverse system is obtained, which is compounded with the original system into a pseudo-linear inverse system that consists of two independent subsystems, including a first-order d-axis current system and a second-order rotational speed system, to decouple the permanent magnet synchronous motor system. Third, the first-order d-axis subsystem is controlled by sliding mode control with a hyperbolic tangent function as the switching function, and the second-order speed subsystem is controlled by super-twisting sliding mode control with a hyperbolic tangent function as the switching function, which is called the synthetical sliding mode control. The permanent magnet synchronous motor pseudo-linear inverse system is controlled by using the synthetical sliding mode to realize the chaos control of the permanent magnet synchronous motor. Finally, three kinds of permanent magnet synchronous motor chaos control systems are established in MATLAB/Simulink software, and the experimental tests are implemented. The results show that the proposed permanent magnet synchronous motor chaos control system has good performance, which can effectively eliminate chattering in sliding mode control and control chaos in the permanent magnet synchronous motor system.
There is great concern about air pollution caused by fine aerosol particles, which are difficult to be removed by conventional removal system. Acoustic agglomeration is proved to be a promising method for particle control by coagulating the small particles into larger ones. Removal efficiency was grown rapidly as acoustic intensity increased. A standing-wave tube system with abrupt section was designed and built up to generate high intensity sound waves above 160 dB and avoid strong shock waves. Extensive tests were carried out to investigate the acoustic field and removal characteristics of coal-fired inhalation particles. For the development of industrial level system, a high power air-modulated speaker was applied and an insulation plate was used to separate flow induced sound. Separate experiments to determine the difference of plane standing-wave field and high order mode were conducted. The experimental study has demonstrated that agglomeration increases as sound pressure level, mass loading, and exposure time increase. The optimal frequency is around 2400 Hz for attaining integral removal effectiveness. The agglomeration rate is larger (above 86%) as much greater sound level is achieved for the pneumatic source and high order mode. The mechanism and testing system can be used effectively in industrial processes.
In order to accurately determine the growth of greenhouse crops, the system based on AVR Single Chip microcontroller and wireless sensor networks is developed, it transfers data through the wireless transceiver devices without setting up electric wiring, the system structure is simple. The monitoring and management center can control the temperature and humidity of the greenhouse, measure the carbon dioxide content, and collect the information about intensity of illumination, and so on. In addition, the system adopts multilevel energy memory. It combines energy management with energy transfer, which makes the energy collected by solar energy batteries be used reasonably. Therefore, the self-managing energy supply system is established. The system has advantages of low power consumption, low cost, good robustness, extended flexible. An effective tool is provided for monitoring and analysis decision-making of the greenhouse environment.
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