Applied Mechanics and Materials Vols. 416-417

Abstract: Control of the process of ACC/DEC (Acceleration/Deceleration) is one of most complicated problems in CNC system development. With the increase of acceleration and velocity in high-speed, high-precision CNC system, discontinuousness of acceleration will result in vibration, impact and debasing of position accuracy. The excellent ACC/ DEC control can solve these problems and improve the positioning precision. In this paper, S curve ACC/DEC algorithm is deeply studied, through comparison with other algorithms; its proved to be an efficient way in advanced CNC system. Usually, such kind of algorithm requires high-speed processor. However realization based on SCM (Single Chip Machine) is proposed in this paper. Through simulation, the result shows that the algorithm works well. Finally practical tests are carried out in Panasonic Minas A5 servo motor which indicates the control system is effective and accuracy.

Abstract: In permanent magnet linear synchronous motor (PMLSM) direct drive system, disturbance caused by load disturbance and perturbation of motor parameters would reduce the control precision in a certain extent. In order to restrict the disturbance in PMLSM direct drive system, a vector control (VC) strategy based on the disturbance observer (DOB) was proposed in this investigation. By using the observed disturbance of DOB to adjust the given value of current in speed loop, the compensation for a sudden disturbance is optimized and a high precision of PMLSM drive system is obtained. For the sake of improving the dynamic performance under unknown disturbances, the traditional PID controller in speed loop was replaced by a single neuron PID controller, which leads to a good adaptive capability and a better starting performance in a given speed. Finally, a higher steady precision and robustness would be realized.

Abstract: Vibration excitation of the machine structures caused by high speed drives often leads to production inaccuracies. By coupling two opposed driving and corporate acting linear drives in one drive train the static and dynamic properties can be improved. This arrangement offers the possibility to distribute the forces between both drives. Furthermore the impulse and jerk feedback into the machine structure can be minimized. In addition de-and acceleration energy can be saved in the coupling element. In order to guarantee the requirement for high accuracy in synchronous tracking as well as to realize pretension of both drives for high acceleration, control strategies and controller tuning methods are going to be discussed based on simulation results.

Abstract: In order to solve the high-frequency chattering and low anti-disturbance in conventional variable structure control (VSC) method with sliding mode, a compensator scheme of introducing integral structure before control object is proposed. Firstly, the position loop VSC state equations and equivalent control model are established based on the analyses of the mathematical model of permanent magnet linear synchronous machine (PMLSM). Then it presents a more accurate and comprehensive method to determine the control parameters and the equivalent model parameters. Computer simulation with the motor parameters of a flat type PMLSM verifies the feasibility and effectiveness of the compensator structure. Compared with the conventional VSC, the proposed structure can solve the vibration caused by external disturbance and load variations, and attenuate the chattering effectively. It is concluded through further analyses that the proposed structure can overcome the system oscillations generated by mover mass and permanent magnet flux linkage, and improve the robustness and control precision of the system.

Abstract: Effected by sensor measurement noise, system noise and load disturbance torque, dynamic performance of low speed compound direct-drive permanent magnet synchronous machine (PMSM) decreased and speed fluctuation increased, which result in creeping phenomenon and unstable working state of servo system directly driven by PMSM. A load torque observer based on extended kalman filter (EKF) is proposed here, which gives correct estimation of rotor position, rotor speed and load torque through electromagnetic torque and encoder signal. A control strategy using estimated load torque for forward feedback compensation is also discussed with no need of extra hardware equipment. Simulation results showed that PMSM can operate steadily at the speed of 2.5r/min with less speed fluctuation only using a low resolution encoder, which verified the effectiveness and practicability of the method mentioned in this paper.

Abstract: The integrated mathematical model of an interior permanent magnet synchronous machine (IPMSM) system is set up suitable for healthy state, open-circuit fault state and fault-tolerant state in this paper. An on-line open-circuit fault diagnosis method is proposed, the fault-tolerant structure is set to connect the fault phase to the middle of DC link, considering that DC link voltage is not balanced, therefore, an optimized adaptive space vector pulse width SVPWM of four-switch three-phase inverters (FSTPI) under DC-link voltage ripple condition is presented to achieve the maximum torque per ampere (MTPA) control and flux weakening control of the IPMSM system under the fault-tolerant state. Based on the abovementioned research, system simulations are implemented and simulation results are given.

Abstract: The paper presents a new way to control the feed speed of the magnetic levitation linear servo system by adopting optimal time control theory. The optimal switch curve is obtained by building the system model and determining the control variable, control condition and target function. According to the optimal switch curve, the system can realize the optimal control of the speed. The validity of the optimal control theory in this servo system has been proven by modeling and simulating in Matlab/Simulink. The simulation result shows that the execution efficiency of the magnetic linear servo system can be improved by applying the optimal control theory.

Abstract: To import a certain aviation piston engine fuel injector for an object, a synthetic clearance fit and its control was studied. A certain type of general aviation aircraft piston engine with fuel injector has synthetic clearance overrun fault after long time using, causing flight control difficult, and seriously affect the working properties of engine, in the condition of idle state more obvious, easy to cause unsafe events such as engine parking. Send for repair by a large number of fuel injectors and its related parts fit clearance measurement and use effect evaluation, might bring negative influence for the mechanism analysis and effective repair and control scheme are put forward..

Abstract: According to the requirement for variable-frequency power supply when a liner motor runs in a household appliance, a variable frequency speed regulation system of three-phase SPWM is designed based on ATmega48 Micro-controller. The hardware structure, the SPWM technology of software program and V/f control strategy are analyzed. In the end of this paper, experiment waves are illustrated. The results show that the running of the system is simple and convenient; the reliability of the system is excellent.

Abstract: In the high-precision servo control system of permanent magnet linear synchronous motor (PMLSM), the regulation of current loop has a direct effect on the control performances such as accuracy, response speed etc. In order to improve the control performances, a digital current loop control scheme based on DSP and FPGA is presented in this paper. FPGA is used to collect data, while DSP is for completing parallel collection of the input signals read and written from FPGA. P control, P uniting feed-forward compensation control and variable proportional gain control are investigated. Since the method of variable proportional gain can easily meet the requirement of current static error and quick response under different frequencies, PI control can basically eliminate the static error. With rotor initial positioning method, the current closed-loop control is proposed and compared with current open-loop control.