PWM controlled Micro ER Valve and Its Application to Micro Actuator Control

电流变液是一类在电场作用下能在几毫秒内发生剧烈的可逆流变变化的功能流体。因此，在电流变流体液压回路系统中，不可能使用仅由电极组成而没有移动部件的电流变阀来控制压力和流量。在这项研究中，电流变阀的PWM控制已被提出，因为电流变阀作为一个ON-OFF阀工作，为了开发一个由PWM控制的微型电流变阀驱动的微致动器系统，具有小型化的电流变阀，以下调查已经完成。(1)研究了由两个玻璃电极组成的电流变阀在直流电控制和PWM控制下的流量控制特性和微流态，分析了差距大小、外加直流电场强度、PWM波载波频率和压差对电流变阀流量控制特性的影响。 关于我们 阐明了电流变液阀的流量控制特性和微观流型。(2)对于电流变流体在由两个玻璃电极组成的二维矩形通道内的振荡流动。已经使用显微镜观察到微观结构的流动图案，其涉及从限定的流体应变和压力差之间的关系评估的ER流体的粘弹性。流体应变的振幅和振荡流的频率和所施加的电场强度的影响已被澄清。(3)在此基础上，研制了一种由一对微型电流变阀驱动的三端口电流变阀驱动的微型波纹管执行器，并对几种PWM控制电流变阀的同步控制策略进行了试验，确定了最佳的控制策略。在此基础上，将电流变阀PWM波占空比与PID补偿器的输出信号成比例变化的P11）补偿器位置反馈控制策略应用于所研制的微型执行器，研究了其控制性能，构建了一个高精度的电流变微伺服系统。少

ER fluids are one of a family of functional fluids, which show dramatic and reversible rheological changes in several millisecond when the electric field is applied. Therefore, in the ER fluid hydraulic circuit systems, it impossible to control the pressure and flow rate using an ER valve consisting of only electrodes with no moving parts. In this research, the PWM control of the ER valve has been proposed because the ER valve works as an ON-OFF valve, and in order to develop a micro-actuator system driven by PWM controlled micro-ER valves featuring the miniaturization of the ER valve, the following investigations have been done.(1) The flow rate control characteristics and micro flow patterns of fundamental ER valves consisting of two glass electrodes whose gap ranges from 0.8 to 0.1 mm have been investigated under DC electric control and PWM control, and the effects of the gap size, the applied DC electric field strength, the carrier frequency of the PWM wave and the pressure differe … More nce across the ER valves on the flow rate control characteristics and micro flow patterns have been clarified.(2) For the oscillatory flow of an ER fluid within a two-dimensional rectangular channel consisting of two glass electrodes. the micro-structural flow patterns have been observed using a microscope, relating to the viscoelastic properties of the ER fluid evaluated from the relationship between a defined fluid strain and the pressure difference. The effects of the fluid strain amplitude and frequency of the oscillatory flow and applied electric field strength have been clarified.(3) On the basis of the above results, a miniature bellows actuator driven by three ports ER valve having a pair of micro ER valves has been developed, The several synchronized control strategies of a pair of PWM controlled ER valves have been tried to determine the suitable one. And then, a position feedback control strategy with P11)compensator in which the duty ratio of PWM wave for the ER valves was varied in proportion to the output -signal of the PID compensator was applied to the developed miniature actuator, and the control performance was investigated to construct a high precision micro servo-system using the ER fluid. Less