Characterizing and Modelling a Sonar Ring

Effective sensor integration requires knowledge of the characteristics of all sensor subsystems. This type of meta-knowledge can originate from theoretical models of the physical processes involved in the sensing, from actual testing of the sensory system or from a combination of both. This paper describes the collection and analysis of experimental data from an actual sonar ring. The effective beam pattern is mapped and modeled for the eight possible setting combinations of pulse width and gain profiles, using three different sizes of targets. The beam cross sectional characteristics are also analyzed to show the effective signal strength and its effect upon error in the depth readings. The performance of the system is highly dependent upon surface texture and orientation, and other tests of the sonar ring illustrate the types of artifacts which arise in the actual use of the system. The test results can be used to provide better certainty values in certainty grid representations, or used to build a boundary representation from a composite scan which integrates the data from the scans at different settings. The test results are shown graphically.