Study Of The Senserless Temperature Control System Of Ultrasonic Actuating Pump

The number of people suffering from heart failure is increasing every year while hearts for transplant are severely not enough. Most of the end stage heart failures need a supporting system for mechanical circulatory, assisting or replacing parts of heart. Our team develops the ultrasonic actuating pump for ventricular assist, as one of the supporting system for mechanical circulatory, which is looking forward to serving as an effective supplement of heart transplant or providing a new way of treatment and ventricular assist in the future.The ultrasonic actuating pump is a pulsatile artificial heart, driven by ultrasonic motor, and pulsates through cam pushing plate. The characteristic of this device is the pulsatile flow it produces, which simulates real hearts. Furthermore, the pump is easy to control as well as possible to implant because ultrasonic motor itself works with high torque and small volume. Meanwhile, ultrasonic motor fevers in working, which has a poor influence in implanting. Temperature rise will destroy blood, organs, tissue and even reduce life of the motor itself as well. In order to measure and control the temperature of pump inside of people body, sensorless and noninvasive pump temperature measurement system is designed and it can prevent sensor lines from damaging body.In this paper, a sensorless temperature prediction and control system of the ultrasonic actuating pump is designed. Firstly, the whole power loss is quantified. The neural network improved by genetic algorithm, then, is applied to predict the pump’s temperature through easily detectable parameters. And the noninvasive detection of temperature is accomplished, temperature date as feedback, based on the method of changing the driving frequency. Finally, the control system keeps a balance between the temperature rise and the output capacity of the ultrasonic actuating pump. Up to now, the results are as follows:1. The principle of the temperature rise for the ultrasonic actuating pump was studied, especially the ultrasonic motor itself and cam friction. Furthermore, approximate power range of them is quantified, which gives a guide to know the whole temperature rise of the pump.2. In all system parameters, easily detected ones with strong correlation are selected and applied to predict the temperature by BP neural network. Genetic algorithm is used to improve the accuracy of prediction and simulation of large sample is made to verify the improvement of accuracy.3. Design of the senserless temperature control system of ultrasonic actuating pump, based on CompactRIO real-time platform, balances the temperature rise characteristics.4. A mock extracorporeal circulation system was built in addition to simulate left ventricle and the ultrasonic actuating pump, which are used to acquire simulation body parameters. The system is used, after that, to measure pump pressure-flow characteristic curve and verify the performance of temperature control.