Resolving Observer Motion by Object Tracking

Abstract

A fundanental sub-problen of the task of interpreting the sonar data gathered by a 1nobile suhnersible robot vehicle is that of construe ting and ,~aintaining a stationary global reference frame in 1.rhich interpretation can take place. Such a frane may be established by tracking the 1aoveraents of objects in the local environment of the robot and using the data so obtained to deduce the notion of the observer. In a marine context, where currents nake it impossible to hold a vehicle stationary for any extended period, it is important to track the vehicle and object motion continuously in real time. In this paper the problem of establishing a stationary reference frame using noisy, specular, intermittent sonar data is discussed and a conputat ional method for its solution is presented • The nethod has been tested by conputer simulation in a two dimensional context and an evaluation of its perfon1ance is given. The solution presented is not restricted to marine vehicles but is especially effective for land-based vehicles, where operating conditions are less severe.