The Application of Methods of Robust M-Estimation in Establishing Ship Position in Marine Traffic Surveillance Systems Based on Radar Observations

Polish Maritime Research

Guze

Świerczyński

2018

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The main source of information on the situation across the sea basins used by operators of shipping monitoring systems is a network of coastal radar stations. Presently, it is possible to gather navigational information from many individual radar stations simultaneously, which may be used for improving the accuracy of vessel position fixing. However, without making other estimates, we obtain an inconsistent image comprising multiple echoes of the same ship, and as such it is impossible to say which echo presents the vessel on the move. Another problem is the method of performing radar observations, which significantly affects the accuracy of position fixing. The estimated radar distance is encumbered with a gross error in the case of large vessels, as the position of a large vessel is not the same as the position of the edge of the radar echo to which the estimation is made. In this paper, the authors present a method to adjust the measured radar distance. The proposed method may be automated easily, which would significantly enhance VTS positioning processes.

“…Then, in accordance with formula (12), adjustments are made to the measured distances for particular values of the aspect:…”

Section: Tab 3 Bearings Taken By the Coastal Radar Stations On The Shipmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Impact of Radar Distance Measurement Accuracy on the Accuracy of Position Fixing in VTS Systems

Polish Maritime Research

Guze

Świerczyński

2018

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“…This paper is an extension of the research presented in (Świerczyński, Czaplewski 2013(Świerczyński, Czaplewski , 2015. Our study aims at determining whether the application of different weight functions and different variants of parameters, which control robust observation adjustment, has a significant effect on the accuracy of vessel positioning in navigation networks.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of outlying observations on the final result of estimation in these methods is eliminated or at least limited by application of the appropriate weight function. Such an approach to working out observations acquired from coastal radar stations has been proposed and discussed in detail in previous papers (Czaplewski 2004;Świerczyński, Czaplewski 2013Świerczyński, Czaplewski , 2015. These papers propose the application of the Danish weight function in the process of robust adjustment of navigational observations, and, in consequence, in determination of reliable coordinates of the vessel position.…”

Section: Introductionmentioning

confidence: 99%

Analysis of A Practical Application of Geodetic Methods of Robust Estimation in a Vessel Positioning Based on Radar Observations

Zienkiewicz

Proccedings of 10th International Conference "Environmental Engineering"

2017

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Abstract. This paper analyses whether the application of robust estimation methods can prevent incorrect vessel positioning, thereby improving navigation safety. Empirical analyses were carried out assuming that the observational vector y comprises observations acquired from coastal radar stations operating within the "VTS Gdańsk Bay" system. Particular attention was paid to a situation in which one of observations has a gross error. Numerical tests were carried out considering several variants of the number of redundant observations. Since the significance of the subject matter in this study arises from the dynamism of position changes of a measurement item, measurements cannot be repeated at the same position. For the same reason, it is very important to choose the optimum method of working out the observations. The results of the robust adjustment of radar observations were compared with the results of the conventional least squares method.Keywords: geodetic adjustment, robust estimation, radar navigation.Conference topic: Technologies of geodesy and cadastre. IntroductionVessel tracking systems (VTS) are established in basins with intensive ship traffic and the presence of navigation hazards creates a considerable risk of collision or other maritime disaster. A VTS is established by a marine administrative body of the state with sea access in order to improve navigation safety, environmental protection or to streamline vessel traffic. Depending on the needs, the basin shape and vessel traffic stream, a VTS can include a port and an approach to it (e.g. Rotterdam Port) or an approach to several ports situated close to each other (e.g. Gdańsk Bay), etc. The area covered by the system is usually serviced by the control centre. The main task of each centre is to analyse the navigational situation in the area and VTS centre operators must have complete and precise information on the position of the vessels moving in the basin in which the VTS is established. It is extremely important for an operator to have as precise a position as possible together with an assessment of its quality, for example using satellite systems (see Specht et al. 2015;Specht, Rudnicki 2016). The authors of this paper have analysed modern analytical methods to streamline the work of a VTS operator. The effects of one of the work stages are presented in this paper. VTS Gdańsk Bay, where the theoretical assumptions were verified, has been operating since 1 May 2003. It serves VTS system users and supervises navigation safety within the area of its responsibility. The VTS Gdańsk Bay system was accepted in October 2007 and approved formally during the 83rd session of Maritime Safety Committee IMO. As decided by the IMO's Maritime Safety Committee, the regulation became effective on 1 May 2008. The system has been employing:

“…Then, it is possible to limit the influence of outliers on the final adjustment with the use of various weight functions, such as Huber's, Hampel's or Danish. This kind of approach to the processing of observations from coastal radar stations was proposed and described in detail in research papers (Czaplewski 2004, Świerczyński, Czaplewski 2013, 2015. However, the use of calculation strategy referring to the principles of robust M-estimation is often associated with the risk of incorrect specification of control parameters.…”

Section: Introductionmentioning

confidence: 99%

Application of Square M_split Estimation in Determination of Vessel Position in Coastal Shipping

Zienkiewicz

Polish Maritime Research

2017

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The main aim of this paper is to assess the possibility of using non-conventional geodetic estimation methods in maritime navigation. The research subject of this paper concerns robust determination of vessel's position using a method of parameters estimation in the split functional model (M split estimation). The studies performed will help in finding out if and in which situations the application of M split estimation as the method for determining vessel's position is beneficial from the perspective of navigation safety. The results obtained were compared with the results of traditional estimation methods, i.e. least squares method and robust M-estimation.