Applied Mechanics and Materials Vols. 668-669

Abstract: Due to the complexity of greenhouse environment, greenhouse system cannot be controlled perfectly by traditional control method. This paper proposes a novel greenhouse control system based on fuzzy neural network to regulate the internal climate of the greenhouse. Temperature and humidity are selected as the inputs of controller, while the skylight, sun-shade net, circulation fan, side windows, fuel heater, and micro-mist humidifier are selected as the outputs. After analyzing every situation that may occur in the control process and the corresponding control strategies, we obtain 35 control “IF-THEN” rules. Simulation results show that the fuzzy neural network controller have certain improvements than the conventional PID controller in the aspects of overshoot, stability and response time.

Abstract: With the rapid development of aeronautics technology, hypersonic flying vehicle is playing an increasingly important role, yet control methods on such vehicle were stilled confined with classical PID (proportional, integration and differentiation) or its variations. In order to have better control performance, a switching control method was used to design the attitude control law for hypersonic missile, which guaranteed higher angle precise control than PID. Simulation results showed the effectiveness and the superiority of the proposed switching methods over the classical PID and other typical switching methods.

Abstract: The pneumatic cylinders are difficult to be controlled due to flow characteristics of control valves, compressibility of air, and static and dynamic friction forces. This paper describes the development of a robust controller based on H_∞ control theory for positioning control of a high-speed pneumatic cylinder. To design the H_∞ controller, one has selected appropriate weighting functions of pneumatic servo system.Simulation results show that the system is robust during the whole response process and can suppress the disturbance. Finally experiments have been performed with varying supply pressures and load mass. Experimental results imply that good performance and robustness of positioning in pneumatic servo system can be obtained using H_∞ controller.

Abstract: This paper concerns the design of robust controller for a linear system with time-varying state and input delay. The new adaptive sliding mode control algorithm of the system with multiple delays in system states and control inputs are proposed. The delay dependent conditions of the closed loop system are formulated and the equivalent gain of the adaptive sliding mode controller is obtained in the form of linear matrix inequalities (LMI). Finally, simulation results of a numerical example based on a practical inverted pendulum shows both the feasibility and efficiency of the proposed controller.

Abstract: An improved controller based on ADRC is proposed for motion control with high frequency disturbance. Firstly, relationship between bandwidth of LESO and its parameters was mentioned, and bandwidth limitation come from the sensor noise is presented, indicating weakness of traditional LESO on compensation high frequency disturbance. Based on such analysis, two FIR filters is designed and added into the control loop, which compensated the specified high frequency disturbance and expanded bandwidth of LESO, acquiring a better motion control result. Simulations are taken, showing validity of the improved controller.

Abstract: In accordance with the features of non-linear, large time-delay and time varying for ferment process, an algorithm combining Fuzzy Control and Human-simulation Intelligent control is presented: Fuzzy control and human-simulating control algorithm is used to control the ferment process of supplying suger. The simulation research shows the algorithm is a very effective algorithm with very good anti-delay and anti-disturbance, especially suitable for the objects with large time-delay and strong disturbance.

Abstract: In order to improve the dynamic characteristic of regulating valve system based on traditional fuzzy PID, a control strategy was presented and this method combines fuzzy PID and improved GA (genetic algorithm) to optimize fuzzy rules. Finally a simulation was carried on in MATLAB. The results show that: Compared with the traditional PID, the fuzzy PID enables the system to achieve better dynamic characteristics.

Abstract: Considering the feature of mine local ventilator, the paper proposed a kind of control method combined fuzzy control and PID control to local fan. According to the error and error change of gas concentration, the system automatically adjusted PID controller’s parameters, to having adaptive capability. The monitoring of gas concentration and frequency inverter speed control of fan can be made with the system using TMS320F2407 DSP as the core.

Abstract: Energy model is an important part to research energy system of iron and steel enterprise and the basis of energy saving. Based on the analysis of iron steel enterprise production process, material and energy employed in the iron-making process were extracted. According to the hybrid characteristics of energy systems in iron and steel enterprises, the hybrid Petri net was used for modeling material and energy of the iron-making process. The MATLAB simulation with the stateflow toolbox based on hybrid Petri net was given. The model was proved that it was able to provide further support to energy conservation and control in the actual production.

Abstract: Combined with the wavelet analysis, the fuzzy theory and the BP neural network this paper constructs the fault diagnostic method of the wavelet fuzzy BP network. In the process of the automotive fault diagnosis, through comparing the common BP neural network with the wavelet fuzzy BP network, the result indicates that the wavelet fuzzy BP network has the characteristics of higher precision and faster convergence speed etc.