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

Abstract

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: