压力是液压系统的重要参数之一，与系统的运行状态密切相关。超声波在液体中传播时，可以作为液体压力信息的载体，因此，通过测量声速进行换算则可获得压力的大小，这是一种液压系统压力非接触式超声波检测方法。与传统的接触式检测方法相比具有安装方式灵活，使用简便，不改变液体状态，不产生附加阻力等优点。然而大量资料表明，用超声波非接触式检测压力参数的研究尚属于探索阶段，非常值得人们去研究。 本课题在吸取成熟的超声波测量流量理论及其有关硬件电路的基础上，研制出一套以单片机技术为核心的实验超声波测压仪。该仪器利用“脉冲回鸣法”作为超声波声速测量的方法，电路简单易行且信号测量准确； 运用人工神经网络的方法构建数学模型，建立声速与压力之间的对应关系，提高了系统的精度；设计传感器驱动电路、自动增益控制电路和接收探头控制电路等电路,重点解决了超声波信号的有效检测问题；采用了光电耦合集成电路、滤波电路、隔离驱动、看门狗监视器、软件陷阱等软硬件抗干扰方法，提高了系统的稳定性和抗干扰的能力；利用单片机作为该测试仪硬件电路的主控芯片，简化了系统结构，降低了系统成本。 总之，通过对本测试系统进行初步的研究和探索，表明本文所提出的非接触式超声波液压压力检测方法是可行的。

Pressure is one of the most important parameter of hydraulic system. It can reflect directly that whether hydraulic system is in good performance. Ultrasonic may carry out the pressure signal of hydraulic system when it passes the liquid. So we can get the pressure size of hydraulic system in virtue of ultrasonic velocity through conversion. This is a free-contact pressure measurement method, and it has huge advantage in convenient installation, turndown hydraulic system state and no excess pressure drop in compare with traditional contact pressure measurement method. It is a very preferable hydraulic pressure measurement instrument adapting to the occasion of worse condition and system malfunction and so on. However, large data indicates that the research of free-contact pressure measurement method belongs to exploring phase, and the method is good for the research. A single-chip microcomputer measurement system has been designed on the base of mature theory in testing flow and its instrument. A reasonable pulse-echo method is chosen to test ultrasonic velocity. The artificial neural networks are used to build the system model of ultrasonic velocity and hydraulic pressure. Then an experiment ultrasonic hydraulic pressure measurement instrument is developed which is vitally settled in the circuit of driving sensor, automatic controlling gain and controlling receiving sensor. Of course, an anti-jamming methods are used in software and hardware, including photoelectric coupling circuit, filter circuit and insulating drive circuit and so on. As a word, the method put forward is feasible from the primary research of the measurement system.