电磨头高精度大端面加工

本文介绍了采用数字变频方法,将电动磨头由高速调整到低速,以提供适合于磨削加工的工件转速,解决了高精度大直径端面加工的难题.     

Viscoelastic effects in nanometer‐scale contacts under shear

We demonstrate the effects of shear modulation on the viscoelastic response of nanometer‐scale single‐asperity contacts under static and dynamic loading conditions. Contact stiffness and relaxation time are determined for contacts to poly(vinylethylene) using a scanning force microscope (SFM). Knowledge of the torsional stiffness κ_Θ of the SFM cantilever is not required to determine the relaxation time. The relaxation time was several orders of magnitude slower than the bulk relaxation time but decreased slowly to the bulk value as the sample age increased. Contacts showed no evidence of microslip. We show that the shear response observed during the making and breaking of the contacts provides information about the time evolution of the contact area that is not available in force vs. distance curve measurements. This revised version was published online in June 2006 with corrections to the Cover Date.     

可调频闪仪的结构及其工作原理

本文介绍了一种新型的可调频闪仪的结构及其工作原理。利用该仪器可获取振动、高速旋转或作周期运动构件的单一“静止”,或者两个及多个位置的“静止”图象,并可观察构件的运动轨迹。文中给出了测量实例。     

六自由度测试系统

本文所描述的测试系统基于激光全息分光技术和激光干涉测长技术,同时测定目标物体六个自由度的偏差。采用激光漂移补偿技术建立了稳定的激光束基准,采用磁光调制技术减小光强不稳定等因素对滚转角测量精度的影响,实现了多自由度较高精度的准直。实验表明,在激光光源距靶标１ｍ时,该系统σ重复性误差：线位移小于４μｍ,角位移小于４″,整个系统结构简单,测量效率高。     

两足步行爬壁机器人控制系统的研究

本文提出了一种新的具有七个自由度的两足爬壁机器人，该爬壁机器人具有重量轻，控制精度高，速度快等特点。     

基于模糊PID控制的半导体制冷片温控系统的研制

设计了采用模糊PID控制算法的半导体制冷片温度控制系统,该系统可以在没有操作者干预的情况下根据控制系统的实际响应情况,自动实现对PID参数调整,控制PWM输出波形的占空比,使温度控制器的工作温度保持恒定。模糊PID控制将模糊控制与常规PID控制结合起来,兼顾两者的优点,改善了控制系统的性能。     

变频器在电火花线切割机床上的应用

机床丝筒电机的控制方式通常采用继电器控制,但采用此方式控制存在一系列弊端。变频器是通过对交流电频率的控制,达到控制电动机转速的目的。文章所述方法充分利用了变频器的功能特点,实现起来线路简单,可维护性好。故改用小功率变频器来实现原控制方式。     

A self-sensing technology of active magnetic bearings using a phase modulation algorithm based on a high frequency voltage injection method

Conventional AMB(active magnetic bearings) systems consist of electromagnetic coils, position sensors, power amplifiers and a feedback controller. This hardware configuration can lead to a structural complexity, problems of space limitations for the installation, and position control difficulties due to the non-collocation of actuators and sensors. In this paper, a self-sensing mechanism is proposed to resolve such limitations of the general AMB system. The proposed self-sensing scheme uses a phase difference of the injected current of two opposite electromagnetic actuators while an object is levitating between the actuators. The relationship between the phase difference of injected currents and the position of a levitated object was theoretically derived and linearized. In order to realize the proposed self-sensing scheme, a signal processing algorithm was developed. The frequency response of the estimator was measured to verify the performance of the proposed self-sensing scheme. In addition, a magnetic levitation and a disturbance rejection response were experimentally obtained to verify the feasibility of the proposed self-sensing mechanism. Experimental results showed that the developed self-sensing technique has similar performance as a practical gap sensor.     

Neuro-fuzzy speed control of traveling-wave type ultrasonic motor drive using frequency and phase modulation

This paper presents a Fuzzy Neural Network (FNN) control system for a traveling-wave ultrasonic motor (TWUSM) driven by a dual mode modulation non-resonant driving circuit. First, the motor configuration and the proposed driving circuit of a TWUSM are introduced. To drive a TWUSM effectively, a novel driving circuit, that simultaneously employs both the driving frequency and phase modulation control scheme, is proposed to provide two-phase balance voltage for a TWUSM. Since the dynamic characteristics and motor parameters of the TWUSM are highly nonlinear and time-varying, a FNN control system is therefore investigated to achieve high-precision speed control. The proposed FNN control system incorporates neuro-fuzzy control and the driving frequency and phase modulation to solve the problem of nonlinearities and variations. The proposed control system is digitally implemented by a low-cost digital signal processor based microcontroller, hence reducing the system hardware size and cost. The effectiveness of the proposed driving circuit and control system is verified with hardware experiments under the occurrence of uncertainties. In addition, the advantages of the proposed control scheme are indicated in comparison with a conventional proportional-integral control system.     

基于PWM的直流伺服电机电感匹配计算方法

脉宽调制（PWM）是直流伺服电机驱动的常见方式之一,回路感值匹配是驱动设计的重要内容。以某型光电稳瞄吊仓直流伺服系统为研究对象,结合国内关于PWM驱动直流电机的设计技巧,推导得到了电流纹波的计算公式,并列出了直流伺服电机基于PWM控制时的回路电感设计准则。仿真试验验证了结果的正确性,为同类系统的设计提供了参考依据。