An Underwater Visual Navigation Method Based on Multiple ArUco Markers

Underwater navigation presents crucial issues because of the rapid attenuation of electronic magnetic waves. The conventional underwater navigation methods are achieved by acoustic equipment, such as the ultra-short-baseline localisation systems and Doppler velocity logs, etc. However, they suffer from low fresh rate, low bandwidth, environmental disturbance and high cost. In the paper, a novel underwater visual navigation is investigated based on the multiple ArUco markers. Unlike other underwater navigation approaches based on the artificial markers, the noise model of the pose estimation of a single marker and an optimal algorithm of the multiple markers are developed to increase the precision of the method. The experimental tests are conducted in the towing tank. The results show that the proposed method is able to localise the underwater vehicle accurately.

PROSPECTS FOR THE USE OF GLONASS IN SOLVING SPECIAL PROBLEMS

Представлен обзор навигационной аппаратуры потребителей, предназначенной для решения специальных задач, которые в условиях бурного развития навигационных услуг вызывают широкий интерес как у гражданских, так и у военных заказчиков. Рассмотрены следующие специальные задачи: навигационное обслуживание строительства сложных высотных и протяженных объектов; надводная и подводная навигация судов, в том числе в Арктике; и подземная навигация. Показано, что в настоящее время решение этих задач достигло определенного успеха, но все еще остаются проблемы, которые требуют быстрого решения. The article presents an overview of consumer navigation equipment designed to solve special problems. The equipment in conditions of rapid development of navigation services is of wide interest to both civil and military customers. The following special tasks are considered: navigation maintenance of construction of complex high-rise and long facilities; surface and underwater navigation of ships, including in the Arctic region; and underground navigation. It is shown that at present the solution of these problems has achieved some success, but there are still unsolved problems that require a quick solution.

Magnetic position sensors

Magnetic position sensors are popular in industrial and automotive applications since they are robust, resistant to dust and oil and they can be cheap. However, precise magnetic position sensors can achieve 0.015 % accuracy and 10 nm resolution. The maximum achievable range is about 20 m. DC magnetic position sensors are using a permanent magnet as a field source. As a field sensor, magnetoresistors are often used instead of traditional Hall sensors. Eddy current sensors work also with non-magnetic conduction targets. Magnetostrictive sensors are based on the time-of-flight of the elastic wave excited in the magnetostrictive material. The sensors can be several meters long and their applications range from level meters to hydraulics. Magnetic trackers and long-range position sensors utilize AC field sources, which are detectable from distances up to 20 m. Compared to optical instruments magnetic trackers do not need direct view. Their applications include surgery, mixed reality, and underground and underwater navigation.