An investigation into ultrasonic waves in distance measurement

• Main Author: Mohamed Raqeeb Mohamed Hamzah Caffoor.
• Other Authors: Lye Sun Woh
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Aeronautical engineering::Electrical systems and equipment; DRNTU::Engineering::Mechanical engineering::Control engineering
• Online Access: http://hdl.handle.net/10356/40470
• Institution: Nanyang Technological University

This study looks at the investigation into the distance measurement of ultrasonic waves. The purpose of the study is to determine a possible achievement of an accuracy of ±1 mm for a 40 kHz ultrasonic transducer in measuring distance through a series of controlled experiments with varying parameters. A comparison was done between the different forms of distance measuring devices to identify the advantages and disadvantages of Ultrasonic Distance Measuring Devices (UDMDs) against other distance measuring devices. Also, a comparison was done between available devices in the market to find out the accuracies and features specified on the devices. The study is limited to a scope of conducting indoor testing up to a range of 15 m, hence keeping factors like temperature and humidity constant as the experiments were conducted in the same laboratory. A review on literature was also included to form a basis for the design of the experiments. The study looks at the applications of ultrasonic specifically in air to work within the limitations of the project. The study also includes a review on the safety issues while working with similar types of frequencies and its possibilities of effects on pacemakers. The design of the experiments was discussed in detail and the apparatus and equipment used were presented. It was also decided to keep the transmitter fixed at one point for both the calibration phase and the main sets of experiments. The experiment was thus carried out with the parameters varied. The parameters included a direct line of sight between the transducers and a variation of the angles of roll, pitch and yaw applied to one transducer, which in this case is the transmitter. This variation in the study allows for a good basic understanding of the accuracies generated through varying orientations. The results were presented with the use of Statistical Package for the Social Sciences (SPSS). Error bars were in the form of 95% C.I. which provided useful information on the accuracy, reliability and capability of ultrasonic waves in distance measurement. The ultrasonic waves generated by the transducer were only capable of providing reliable accuracies of 1mm tolerance to a certain extent, this being 10m at a direct line of sight and up to 9m at an angle of roll of 5°. On the other hand, experiments involving pitch orientation, and yaw orientation did not meet the target accuracy of 1mm although the potential is there for smaller variations. This implied that the environment of which the transducers were in is vital to the degree of accuracy in distance measurement. Factors like line of sight between the transducers, intensity of ultrasound waves reaching the receiver, surrounding objects scattering the ultrasonic waves and interference from background noises may have affected the accuracy. A series of recommendations such as adding more parameters, conducting an outdoor experiment, a rail construction for movement of the tripods and experiments to attain optimal accuracy through a test between various transducers is suggested to further improve the study and for further exploration into the investigation of ultrasonic waves in distance measurement.