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This paper proposes a new joint positioning and navigation aiding system for underwater robots. In the scenario adopted, a submersed target carries a pinger that emits acoustic signals periodically, as determined by a low precision clock. The target is tracked from the surface by a set of buoys equipped with acoustic hydrophones/projectors, GPS rec...
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During the last decades, underwater robotics has known a widespread interest from different research and industrial communities (Design, sensing actuation, dynamics, control, localization and mapping, etc.) given the multiple tasks they can accomplish. Indeed, their applications are multipole, such as dams inspection, oil and gas industry, fish far...
Abstract—For analysis and mapping as well as long-term studies of water bodies, Autonomous Underwater Vehicles (AUVs) are considered to be a trendsetting opportunity with high potential. Underwater robots combine many benefits differing them from conventional methods like manual explorations with divers and boats or static underwater sensor nets. I...
Underwater robots have garnered more attention in recent years for various uses including deep sea exploration. As these robots operate underwater, they experience various forces and moments from the surrounding fluid. Researches have to be conducted on these forces and moments so that ways to better improve the robots can be discovered. One such m...
In this paper, an improved algorithm for particle swarm optimization is proposed for the application of underwater robot in the complex marine environment. Not only did consider to avoid obstacles when path planning, but also considered the current direction and the size effect on the performance of the robot dynamics. The algorithm uses the trunk...
Citations
... The GNSS/A technique consists of two components: One is monitoring the positioning of an acoustic transducer at the sea-surface through the kinematic GNSS method, and the other is acoustic ranging between the transducer and transponders on the seafloor [1]. The acoustic transducers are usually mounted at the bottom of a ship or buoys, the former often used for relatively short-term activities, such as oil exploration, whereas the latter is mainly used for long-term observation and monitoring with the advantage of low power consumption and cost [22]- [24]. ...
More accurate and realistic stochastic model is required for high-precision underwater positioning. The common stochastic modeling procedure, assuming that the measurements are statistically independent in space and time and have same accuracy, is certainly not realistic. Any misspecification in the stochastic model may have a significant effect on underwater acoustic data processing. Taking the heteroscedastic space and time correlation into consideration, a novel stochastic modeling procedure based on an iterative minimum norm quadratic unbiased estimator method has been developed to improve underwater positioning accuracy. Testing results by experiment data show that the positioning accuracy can be superiorly improved from 1.226, 1.434, and 1.018 m based on a traditional stochastic model estimation scheme to 0.935, 0.336, and 0.190 m for three transponders when adopting the new method.
... The increasing use of formations in robotics, as well as the evolution of parallel computing, have led to extensive research on the field of distributed systems and agent formations, see e.g. Barooah (2007), Fax (2002), Tsitsiklis (1984), Middleton, R.H. and Braslavsky, J.H. (2010), and Sousa et al. (2009). In short, a distributed system consists of multiple autonomous computers or agents that communicate information between them and work towards a common goal. ...
This paper addresses the problem of decentralized state estimation in formations of Autonomous Underwater Vehicles (AUVs) with fixed topologies. In the envisioned scenario, each AUV in the formation estimates its own state relying only on locally available measurements and data communicated by neighboring agents, requiring lower computational and communication loads than centralized solutions. A method for designing local state observers featuring global error dynamics that converge asymptotically to zero is detailed, and an algorithm for improving its performance under stochastic disturbances and Gaussian uncertainties is presented. The proposed algorithm aims to minimize the H2 norm of the global estimation error dynamics, expressed as an optimization problem subject to Bilinear Matrix Inequality (BMI) constraints. To assess the performance of the solution, realistic simulation results are presented and discussed for several formation topologies.
... Examples include the inverted USBL, as detailed in Morgado et al. (2007) and in ref- erences therein, terrain-or landmark-relative navigation systems Oliveira (2007), and Long Baseline Systems (LBL) Milne (1983). This paper extends recent joint simultaneous positioning and aiding navigation systems proposed in Sousa et al. (2008), to a scenario where a number of underwater vehi- cles (autonomous and/or tele-operated) can interact dur- ing a mission. Inspired by the GIB approach, that system is composed by three segments: a) Surface Segment: con- sists of a synchronized net of hydrophones and pingers attached to surface buoys that are equipped with GPS receivers; b) Underwater Segment: the submerged targets that emit periodically distinctive signals that are received by each of the hydrophones installed on the surface buoys, which in turn transmit via radio the time of arrival of the signals (TOA) to a control station positioned on a support vessel or on land; and c) Control Segment: using Extended Kalman Filters (EKF), the control station computes the positions of the targets. ...
... The recent joint positioning and navigation aiding system proposed in Sousa et al. (2008), denominated as JPNS, only addressed a scenario where only a single target was present. In a scenario where Z underwater targets are operating at the same time, Z replicas of the JPNSs would be required, in order to aid the navigation systems onboard all the targets. ...
This paper proposes a new joint positioning and navigation aiding system for multiple underwater robots. In the scenario adopted, each submersed target carries a pinger that emits acoustic signals periodically, as determined by a low precision clock. The targets are tracked from the surface by a set of buoys equipped with acoustic hydrophones/projectors, GPS receivers, and electronic circuitry that measures the times of arrival of the acoustic signals emitted by the pinger. The buoys at surface, synchronized with the GPS timing, emit periodically distinctive signals that the underwater vehicles can use as aids to their onboard navigation systems. In the case where buoys drift away more than a pre-specified distance from their nominal positions, coded signals are emitted. The scheme proposed allows for the performance in the tracking and navigation systems to be independent from the number of targets present in the scenario of operation. Simulation results are presented to assess the performance of both the positioning tracker and a simplified onboard integrated navigation system.
An autonomous underwater vehicle (AUV) can achieve precise observation in the sea. Also in Japan agency for Marine-earth Science and Technology (JAMSTEC) some observations with AUV ldquoURASHIMArdquo have been implemented mainly in deep ocean. Tracking or navigation of the AUV is significant to make the observations more valuable. Almost AUV equips an inertial navigation system (INS) to navigate own cruise. The main problem of INS is the drift error of the estimated position, velocity and attitude, and it is not negligible. On the other hand, the AUV is tracked or positioned using acoustic positioning system (APS) in many cases. The APS is direct estimation of the position, and the error is limited but very larger compared with short-time INS tracking. In JAMSTEC, the super short baseline (SSBL) method is almost used to track the AUV from the mother ship because the observation area is deepwater and the SSBL is easy to operate. However, the SSBL is not accurate particularly in deepwater. Furthermore, there is systematic error due to measurement error of the circumstance, such as sound velocity profile. Thus the SSBL estimation is not so good to use to reset the INS estimation of the AUV position. In this paper, an accurate tracking method to estimate AUV potion by SSBL from the mother ship is proposed. In this method, the INS data obtained in the AUV is transmitted to the ship by spectrum spread (SS) acoustic communication. This acoustic signal is also used for SSBL, and the SSBL estimation is implemented by each data symbol. Thus the SSBL estimation is achieved not with a short pulse but with a continuous acoustic signal. The SSBL estimation results and the transmitted INS data are integrated and the AUV position is tracked accurately. Two integration algorithms are introduced. The one considers only the drift error of the INS outputs. This algorithm is linearly modeled and filtered by a Kalman filter (KF). Another also considers the systematic error of the SSBL du-
e to measurement error of layered sound velocity profile. The later algorithm is non-linear and uses extended KF (EKF). The usefulness of these algorithms is shown by simulation. Particularly, the second algorithm is beneficial under existence of the systematic error of the SSBL estimation.
