Application Research Of Spread-spectrum Technology In Ultrasonic Ranging System

Ultrasonic ranging technology is widely used in many fields, for example, level measurement, self-guided autonomous vehicles, fieldwork robots automative navigation, air and underwater target detection, identification, location and so on. Usually, the ultrasonic ranging systems are of small range, which are limited in the application scope. This paper is to study the large-range, high-precision ultrasonic ranging technology, and the application of spread-spectrum technology in measurement, which is of great significance in development of the ultrasonic ranging technology.1. According to the tranducer performance, a disc oscillator and its parameters were selected. The principle and componets of the ultrasonic ranging system were analazed in general. The key parts in the design of transmitting and receiving circuits were proposed. Finally, the sources of error in measurement were discussed, and the compensating methods were given.2. A novel driving circuit of ultrasonic transducer and high-precision echo receiving circuit were designed. In order to improve the efficiency of energy-transform, the impedance matching technology was applied to the ultrasonic transducer, and an optimal designing method for the transmitting circuit was proposed. Finally, the experimental results of ultrasonic distance measurement were given.3. The application of pseudo-random code (PRC) ultrasonic spread-spectrum distance measurement and its processing methods were studied. The m sequence parameters'design method and the modulation mode between pseudo binary sequence (PRBS) and ultrasonic carrier were analyzed. The time delay estimation (TDE) model of ultrasonic spread-spectrum distance measurement was established, and we studied relative algorithm based on it and gave the experimental verification. The measurement precision was analyzed finally.Experimental results show that the range of ultrasonic measuring system is greater than 32 meters, which has better performance than that of the existing ones, for instance, the similar products in Airducer Catalog (AIRMAR Tech. Corp., U.S.A.). At present, the ultrasonic ranging system developed in this paper has been applied. It provided one of the solution of field-object-detection for the key project of"Study on the navigational control theory and methods for mobile robotics in unknown environment"(supported by National Natural Science Foundation of China, authorized No. 60234030) and the project of"Unmanned Campaign Platform"(An Advanced Research Project of the 10th Five-year Plan, supported by Equipment Headquarters).