超声波驱动系统设计毕业论文外文翻译.doc

Ultrasonic ranging system designPublication title: Sensor Review. Bradford: 1993. Vol. ABSTRACT：Ultrasonic ranging technology has wide using worth in many fields，such as the industrial locale，vehicle navigation and sonar engineeringNow it has been used in level measurement，self-guided autonomous vehicles, fieldwork robots automotive navigation，air and underwater target detection，identification，location and so onSo there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging system in hand，satisfy the request of the engineering personnel for the ranging precision，the bound and the usage，a portable ultrasonic ranging system based on the single chip processor was developedKeywords：Ultrasound r，Ranging System，Single Chip Processor1.IntroductiveWith the development of science and technology, the improvement of people's standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system. comfort is very important to people's lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core component of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder.2. A principle of ultrasonic distance measurement 2.1 The principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate. When it's two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibration resonance, ultrasound is generated. Conversely, if the two are not inter-electrode voltage, when the board received ultrasonic resonance, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver. The traditional way to determine the moment of the echo's arrival is based on thresholding the received signal with a fixed reference. The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the object's nature, size and distance from the sensor. Further, the time interval from the echo's starting point to the moment when it surpasses the threshold changes with the intensity of the echo. As a consequence, a considerable error may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2.2The principle of ultrasonic distance measurement Ultrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received by the receiver immediately stop the clock. Ultrasound in the air as the propagation velocity of 340m / s, according to the timer records the time t, we can calculate the distance between the launch distance barrier (s), that is: s = 340t / 2 4. The ultrasonic ranging system software design Software is divided into two parts, the main program and interrupt service routine. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control. Interrupt service routines from time to time to complete three of the rotation direction of ultrasonic launch, the main external interrupt service subroutine to read the value of completion time, distance calculation, the results of the output and so on. 5. Conclusions Required measuring range of 30cm 200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility. Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error. Therefore, it can be used not only for mobile robot can be used in other detection systems. Thoughts: As for why the receiver do not have the transistor amplifier circuit, because the magnification well, integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequency.超声波驱动系统设计原文出处：传感器文摘 布拉福德:1993年 超声波电动机(Ultrasonic Motor，简称USM)是近年来发展起来的一种全新概念的驱动装置，它利用压电材料的逆压电效应(即电致伸缩效应)，把电能转换为弹性体的超声振动，并通过摩擦传动的方式转换成运动体的回转或直线运动。这种新型电机一般工作于20kHz以上的频率，故称为超声波电动机。它由定子(振动体)和转子(移动体)两部分组成，但电机中既没有线圈也没有永磁体，其定子由弹性体(Elastic body)和压电陶瓷(Piezoelectric ceramic)构成，转子为一个金属板。定子和转子在压力作用下紧密接触，为了减少定、转子之间相对运动产生的磨损，通常在二者之间(在转子上)加一层摩擦材料。关键词：超声波，驱动器，单片机 1、前言超声电机是20世纪70年代发展起来的一种新型电机，以其不同于传统电磁电机的独特优势近年来得到迅猛发展。它无磁极无绕组，不需要电磁之间的相互作用来转换能量，而是利用压电材料的逆压电效应实现机电能量转换，将电能转换为超声频率范围内的机械振动( 频率 20 k Hz )，然后将定子的微观变形通过摩擦耦合放大为动子的宏观运动。超声电机具有运行无噪音、大功率密度、不受磁场干扰、可断电自锁等特点，因此自问世以来发展迅速。目前它已被成功应用于航空航天、微机电力系统、精密定位装置、汽车、照相机等领域，基于超声电机众多的优良性能，未来必将获得更加广泛的应用，极有可能取代部分微小型电磁电机。因此，超声波电机驱动控制技术成为微电机领域研究的一个热点。通过对本课题的研究，要求设计超声波电机的驱动电源，并达到两路电源电压的输出，输出电压可调，调节幅度为100-150V,且其频率可调，频率调节范围为100-15KHz，占空比也可调。2、超声波驱动原理 2.1压电式超声波发生器原理压电式超声波发生器实际上是利用压电晶体的谐振来工作的。超声波发生器内部结构，它有两个压电晶片和一个共振板。当它的两极外加脉冲信号，其频率等于压电晶片的固有振荡频率时，压电晶片将会发生共振，并带动共振板振动，便产生超声波。反之，如果两电极间未外加电压，当共振板接收到超声波 时，将压迫压电晶片作振动，将机械能转换为电信号，这时它就成为超声波接收器了。2.2超声波驱动原理超声波电源通常称为超声波发生源，超声波发生器。它的作用是把电能转换成与超声波换能器相匹配的高频交流电信号。从放大电路形式，可以采用线性放大电路和开关电源电路，大功率超声波电源从转换效率方面考虑一般采用开关电源的电路形式。线性电源也有它特有的应用范围，它的优点是可以不严格要求电路匹配，允许工作频率连续快速变化。从目前超声业界的情况看，超声波主要分为自激式和它激式电源。4、超声波电动机对驱动控制器的要求 超声波电动机的主要工作特点是给其施加两相相位互差一定角度的交流电压，利用压电陶瓷的逆压电效应，使压电陶瓷发生谐振并带动定子环一起振动，再通过定、转子之间的摩擦力驱动转子旋转或滑块直线运动。在电激励下，超声波电动机定子表面形成周向行波或驻波。 对于超声波电动机的两组通以互差一定相移的交流电，且当该相位差为某一角度时输出转矩达到最大值。对行波型两个激励源要求相差/2，但对驻波型超声波电动机而言(特别是纵扭复合型)，由于纵扭振子在夹心定子中的位置不同，纵扭振动传播速度不同，很难通过计算得到纵扭振子驱动信号相位，以保证定子表面质点纵扭振动所需的相位差，只能通过测试方法得到，所以超声波电源的两路输出驱动信号应能够在0-180°范围内连续可调。由于超声波电动机是在谐振状态下工作的，不同的超声波电动机，其谐振频率不同。即使是同一超声波电动机，谐振点也不止一个；另一方面，随着温度的变化，其谐振频率本身也会跟着变化。一般超声波电动机的谐振频率在20-100 kHz之间，故超声波电动机电源的频率输出要求20-100kHz，且两相连续可调。另外，从定转子接触面的角度分析，两路驱动电压必须可调节。 纵上所述，超声波电动机对驱动控制器的要求如下： (1)两路驱动信号相位0-180°连续可调； (2)两路驱动信号可反向调节，以改变转向； (3)频率输出20-100 kHz内可调； (4)因驱动对象超声波电动机为容性负载，故要实现阻抗匹配； (5)具有频率、相位自动跟踪功能； (6)两路驱动电压可调。