Localization, Mapping and SLAM in Marine and Underwater Environments

The use of robots in marine and underwater applications is growing rapidly. These applications share the common requirement of modeling the environment and estimating the robots’ pose. Although there are several mapping, SLAM, target detection and localization methods, marine and underwater environments have several challenging characteristics, such as poor visibility, water currents, communication issues, sonar inaccuracies or unstructured environments, that have to be considered. The purpose of this Special Issue is to present the current research trends in the topics of underwater localization, mapping, SLAM, and target detection and localization. To this end, we have collected seven articles from leading researchers in the field, and present the different approaches and methods currently being investigated to improve the performance of underwater robots

Underwater Object Tracking Using Sonar and USBL Measurements

In the scenario where an underwater vehicle tracks an underwater target, reliable estimation of the target position is required. While USBL measurements provide target position measurements at low but regular update rate, multibeam sonar imagery gives high precision measurements but in a limited field of view. This paper describes the development of the tracking filter that fuses USBL and processed sonar image measurements for tracking underwater targets for the purpose of obtaining reliable tracking estimates at steady rate, even in cases when either sonar or USBL measurements are not available or are faulty. The proposed algorithms significantly increase safety in scenarios where underwater vehicle has to maneuver in close vicinity to human diver who emits air bubbles that can deteriorate tracking performance. In addition to the tracking filter development, special attention is devoted to adaptation of the region of interest within the sonar image by using tracking filter covariance transformation for the purpose of improving detection and avoiding false sonar measurements. Developed algorithms are tested on real experimental data obtained in field conditions. Statistical analysis shows superior performance of the proposed filter compared to conventional tracking using pure USBL or sonar measurements

Research Brief

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A SONAR-Based Water Level Monitoring System: An Experimental Design

Storage of water is common to all human for domestic and industrial utilization. Today, water tanks are the conventional and a major component in water storage systems as they have the capacity to hold large volume of water over a long period of time. They come in different shapes and sizes. However inadequate monitoring of water level in this storage facility may lead to either shortage of water supply when needed or its wastage during lifting process. Hence, there is need for proper monitoring of water level in a storage facility. This need motivates this work, which is the development of water level monitoring system that based on sonar technology. Materials employed in the development include ultrasonic sensor module, ATmega-328P microcontroller, 16MHz crystal oscillator, 12V dc water pump among others. The developed system monitors the water level and activates the pump as appropriate based on the input the ultrasonic sensor gives to the microcontroller which occupies the centre of the system. The developed system has potential of mitigating the attendant problems that usually arise from wastage or shortage of water supply with respect to water storage facility. Keywords—SONAR, water storage, monitoring syste