Design and Control Experiments of Piezoelectric Hydraulic Actuators

本文主要研究压电泵的数学模型及其在汽车制动系统中的应用。压电泵由多层压电元件、膜片、泵阀、谐振管和蓄能器组成。在实验中，采用直径为22 mm、长度为55.5mm的压电元件，获得了62 W的最大泵浦功率。在考虑工作液的可压缩性、压电元件的非线性特性、泵阀动作的时滞等因素的基础上，建立了压电泵的详细数学模型，并将实验数据与仿真结果进行了比较，验证了模型的正确性。制动系统由压电泵作为动力源，制动钳及其活塞产生制动力，三位电磁阀改变制动位置组成。结果表明，采用直径33 mm、长55.5mm的压电元件，可获得15 mm/s的活塞速度和20 kN的活塞力。本文还利用扰动观测器建立了以压电泵驱动电压为控制输入的活塞力控制策略。

In this research, we discussed mathematical models of the piezoelectric pump and its application to the automoble brake system. The piezoelectric pump consists of a multilayered piezoelectric element, a diaphragm, pumping valves, resonant pipes and accumulatos, and the maximum pumpimg power of 62W was obtained in the previous experiments by using the piezoelectric element of 22mm diameter and 55.5mm length. A detailed mathematical model of the pump is derived here by considering the compressibility of the working liquid, nonlinear characteristics of piezoelectric element, the time delay of pumping valves action and so on.The validity of the model was illustrated by comparing the experimental data and the simulation results.Using the mothematical model of the piezoelectric pump, a brake system for automoble disk brake was also simulated in this research. The brake system consists of a piezoelectric pump as a power source, calipers and its piston to generate brake force, and a three position solenoid valve to change the sitsuation of brake. It was shown that 15mm/sec of piston speed and 20kN of piston force were obtained by using the piezoelectric element of 33mm diameter and 55.5mm length. The control strategy of the piston force was also constructed in this research by using the disturbance observer where control input was the driving voltage of the piezoelrctric pump.