Patent Document ID: 20120201099
Application ID: 13502113
Patent Status: 0

Claim One:
1. A method for estimation and dynamic correction of absolute position of objects observed on the seabed by a sonar detection system carried by a vehicle being deployed above the bed, an object being detected by the observation of its acoustic shadow, this observation giving rise to the creation of a fictitious object, or contact, whose estimated position is initially that associated with the observation which gave rise to it and which represents the detected object, the method comprising carrying out the following phases: a first phase comprising constructing a fictitious mesh based on the observations performed in the course of time, the mesh being constructed by representing each observation performed by a node whose position is that of the observation and by connecting the nodes together by way of fictitious elastic links; a new observation being associated with a node which is connected to a fictitious anchoring point, situated on the seabed, by a first fictitious elastic link, and which is integrated into the existing mesh by way of a set of fictitious elastic links, each of these links connecting the node to nodes of the mesh corresponding to observations preceding the observation considered in time; a node associated with a new observation being moreover tied by another fictitious elastic link to the node associated with the contact corresponding to this new observation, a node whose position is that of the observation site; the elastic links thus established having initial lengths such that having regard to the positions of the various nodes they do not exert any tension on the nodes to which they are connected; a second phase comprising, when two observations are considered to relate to one and the same object, fusing these observations by associating them with a single contact, whose position is dependent on the two fused observations, the fusion being manifested at the level of the mesh by replacing the nodes associated with the contacts corresponding initially to the observations by a node associated with the new contact formed, this node being tied to the nodes associated with the corresponding observations by way of the fictitious links initially connecting the node associated with an observation to the node associated with its contact; the introduction of this common node into the mesh inducing on the nodes associated with the fused observations tensions which are transmitted to the other nodes of the mesh by the diverse fictitious elastic links and which are resolved by a modification of the positions of the nodes constituting the mesh; the modified position of each node being assigned to the observation or to the contact associated with the node considered; wherein the first phase is implemented throughout the duration of the seabed analysis operation, and the second phase is implemented each time that the fusion of two observations is decided.