Adaptive Kalman Filter Based Single Beacon Underwater Tracking With Unknown Effective Sound Velocity

Abstract

In the single-beacon underwater tracking system, vehicles rely on slant range measurements from an acoustic beacon to bound errors accumulated by dead reckoning. Ranges are usually obtained based on a presumed known effective sound velocity (ESV). Since the ESV is difficult to determine accurately, traditional methods suffer from large positioning error. By treating the unknown ESV as a state variable, a novel single-beacon tracking model (the so called "5-sv" model) and an extended Kalman filter (EKF)-based solution method have been discussed to solve the problem of ESV estimation. However, due to the uncertainty of underwater acoustic propagation, the probabilistic characteristics of the ESV uncertainty and acoustic measurement noise are unknown and varying both with time and location. EKF, which runs with presupposed noise parameters, cannot describe the practical noise specifications. To overcome the divergence issue of EKF-based single-beacon tracking methods, this paper proposes an adaptive Kalman filter-based single-beacon tracking algorithm which employs the "5-sv" model as the baseline model. Through numerical examples using simulated and field data, both the filter and smoother results show that while implementing the proposed algorithm, the tracking accuracy can be significantly improved, and the estimated noise parameter agrees well with its true value.

Frogman Self-Navigation Method Based on Virtual Transponder Array and Dead Reckoning

“…However, this scheme requires the arrangement of multiple underwater acoustic transponders to constitute the transponder array in advance, which is complex and not convenient for the practical applications in small areas or under emergency conditions. To reduce the cost and to make positioning system more suitable for the miniaturized frogman application demands, introducing STR information as external measurement has become a research hotspot in the field of underwater positioning, which has been successfully applied in underwater vehicle navigation [23][24][25]. Reference [23] has proposed a range-only and single-beacon (ROSB) technology for the tracking and positioning of autonomous underwater vehicles (AUVs).…”

“…Reference [23] has proposed a range-only and single-beacon (ROSB) technology for the tracking and positioning of autonomous underwater vehicles (AUVs). Reference [24] has realized the tracking of AUVs by designing a filtering algorithm based on single beacon ranging. Reference [25] has proposed a single-beacon navigation method based on SIMO model to conduct the navigation and positioning of group AUVs.…”

“…Reference [25] has proposed a single-beacon navigation method based on SIMO model to conduct the navigation and positioning of group AUVs. The methods in [23][24][25] use single beacon ranging information as the measurement and suppress the divergence speed of position errors by filtering. However, these methods have not solved the problem that positioning errors accumulate over time under the condition of single transponder configuration.…”