Advanced Engineering Forum Vols. 2-3

Abstract: The traditional PID control in nonlinear system such as high-speed wind tunnel has limitations, and the range of using is limited. The BP neural network has been widely applied to the optimization of the PID controller parameter adjustment. The PID neural network control system is introduced in the conventional PID control, which has advantages such as simple structure, physical meaning clear parameters, but also has a neural network of parallel structure and the function of learning and memory and nonlinear mapping capability. The controller uses BP (error back propagation) algorithm to correct connection weights, through on-line training and learning and make objective function to achieve optimal value. This improvement scheme can not only improve algorithm in the training process, and the convergence speed in the wind tunnel, the control valve control system response speed, high precision, meet the steady-state real-time control requirements.

Abstract: In this paper, based on the output feedback decoupling, curve fitting and spline interpolation method, a mathematical model is presented for nonlinear dynamical system wherein only system inputs and outputs are known.

Abstract: In this paper, we propose a novel scheme of IMC-PID control combined with a tribes type neural network (NN) for the position control of ultrasonic motor (USM). In this method, the NN controller is employed for tuning the parameter in IMC-PID control. The weights of NN are designed to be updated by the tribes-particle swarm optimization (PSO) algorithm. This method makes it possible to compensate for the characteristic changes and nonlinearity of USM. The parameter-free tribes-PSO requires no information about the USM beforehand; hence its application overcomes the problem of Jacobian estimation in the conventional back propagation (BP) method of NN. The effectiveness of the proposed method is confirmed by experiments.

Abstract: Through analyzing the 760mm hydraulic AGC production line of a Shandong factory, the characteristics, compositions and the mathematical model of hydraulic system of the hydraulic AGC are introduced. Based on those the system performance is analyzed on the working conditions by simulations through introducing the PID and fuzzy PID controller. The simulation analysis concluded that the system response time and overshoots with the fuzzy PID controller were better than before, which is in flavor of the production line commissioning and eventually running. The performance of AGC system affects the controlling accuracy of sheet thickness and yield of sheet directly. In order to accommodate the requirement of market and improve the competition of product, a steel plant from Shandong province entrusts relevant department to develop a set of hydraulic system, which is being debugged at present. Our paper mainly introduces the structure and feature of the system. With the mathematical model that accord with the working conditions being founded and PID and fuzzy PID based on the mathematical model being added, We have simulated the system using the software of MATLAB/SIMULINK, which supplies corresponding theoretical basis for the system’s final operation [1].

Abstract: Electro-hydraulic proportional closed control system is designed which fully integrated electrical and hydraulic advantages of both. The dynamic mathematic model of the hydraulic system is built and the dynamic characteristics of the system are analyzed accurately. The advanced PID controller is adopted to correct the system, and have improved the dynamic quality of the system. In this paper, the hydraulic system is simulated on the basis of the Simulink and DSHplus professional hydraulic simulation software and the results of simulation prove that the qualities of the system can satisfy with the requirement much better.

Abstract: Binding the actual production of one sporting goods factory, in order to meet the needs of automatic production line of shooting flying saucer, the discoid products stacking machine was developed based on PLC, carried out mechanical system design of discoid products stacking machine and control system development based on PLC. After production testing proved reasonable structure of mechatronics systems, easy to operate, reliable, able to meet the requirements of automated production, with a strong practical and innovative, have some application value.

Abstract: A two degree of freedom (DOF) lateral dynamic model for a three-axe heavy vehicle is set up and the vehicle ordinary differential equations of motion are derived. The nonlinear lateral tire forces are obtained by Gim model with vertical loads, slip angles and cornering performances of front and rear tires being input parameters. A revised closed-loop single-point preview method is proposed to model the driver’s directional control performance. In this proposed method, the steering angle of front wheels is calculated in real time according to the track error between a certain point ahead of the vehicle and the required route. Then the steering angle is input into the vehicle model to gain the dynamic responses and position of the vehicle in next time step. Thus the driver-heavy-vehicle closed-loop system is built. The dynamic responses of the system are simulated on the condition of double lane change and the effects of system parameters on the path following behavior of the vehicle are researched. Then the advice on how to improve the vehicle directional control ability can be brought forward.

Abstract: Neutral-point potential unbalance is an inherent problem of Neutral-point-clamped three-level PWM rectifiers. If the problem of neutral point can’t be controlled appropriately, the harm of input current will increase, and even the dc-link capacitor and switches will be destroyed. Thus domestic and foreign experts have done lots of research on the balance control of Neutral-point-clamed and put forward many effective control methods. This paper proposes a novel SVPWM strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for the harmonic voltage and the control of neutral-point potential compared to the popular eight-stage centered SVPWM and realizes the balancing control of inverter neutral-point potential by modifying redundant small vectors pairs’ distribution factor accurately, only requiring the information of dc-link capacitor voltages and three-phase load currents, which is convenient to apply and is compatible of digital computer realization. The feasibility of the proposed control approach has been verified via simulation and experiment results. In the strategy of software control, domestic and foreign scholars propose numerous neutral point potential control schemes. When carrier modulation is used, the balance control is achieved by injecting zero-sequence component into the three-phase modulated wave. When space vector modulation methods are adopted, they can be divided into three categories: passive control, hysteresis control and active control. there is also a new algorithm based on the intrinsic relationship between SVPWMs for two—level inverters and three．1evel inverters．a novel SVPWM control algorithm is proposed for three．1evel．The dwell time of voltage vector for three-level inverter can be acquired from counterpart for two-level inverter by using a linear transformation．Aiming to analysis the output PWM sequence of three-level inverter, a novel classification standard of voltage vector is proposed．Based on evaluating the PWM sequences, a novel PWM sequence is given，that can reduce the total harmonics distortion of inverter output.

Abstract: In order to improve the stability of feed movement in high speed CNC system, the feedrate planning algorithm based on piece-wise polynomial function was proposed. The flexible transition of feedrate was realized through maintaining linear continuous jerk. The principle of the proposed algorithm was introduced and the method to generate smooth motion profile based on the proposed algorithm was presented. The rapidity, stability and tracking accuracy of the feedrate planning algorithm to linearity, S curve and the proposed one were analyzed. The proposed algorithm is simple and it can be applied in acceleration/deceleration before interpolation in high speed feed movement to improve the stability of it. The proposed algorithm was applied in multi-contour high speed processing and the result indicated that it could improve the stability of large-scale parts motion.