ORGANIZATION OF GOAL-DIRECTED MOVEMENTS OF VEHICLES USING VISUAL LANDMARKS
Abstract
The report considers the solution of the navigation problem with the help of a technical vision system that determines the position of the mobile vehicle relative to the landmarks indicated in the surrounding space. Navigation by landmarks is the most objective criterion for the location of a mobile vehicle in the surrounding space. The method of measuring the parameters of the ratios that characterize the location of the mobile vehicle relative to the landmarks is almost independent of other navigation measurements. Data input for correcting coordinates and other motion parameters can be performed not continuously, but at some discrete, and, in general, quite rare moments of time. The general scheme of the solution is considered: from setting up, to receiving navigation information. The integration of the obtained data with data from other navigation tools is briefly described, and the key problems and parameters of the VS that affect the accuracy of the obtained results are analyzed. The key point in this method is the solution of a system of equations describing the position of robotic complexes relative to the specified landmarks. This system is solved by a modified Gauss-Newton method for a nonlinear redefined system of equations. By replacing the left side of each equation with its differential at the point of initial approximation, linearization is performed. The values of the unknowns in the redefined system of linear equations for which the sum of the squared residuals in the equations is minimal can be obtained either by the SVD (singular value decomposition) method or by using the system's symmetrization. At the same time, SVD is more resistant to the accumulation of computational error, but it is somewhat more demanding on computer resources and more difficult to implement. We used the symmetrization solution as a simpler one. The resulting system is solved by the square root (Cholesky) method. To detect landmarks in the VS, two types of VS modules are used – panoramic, based on a camera with a fish-eye lens, and stereo. The proposed method allows us to solve the problem of clarifying the parameters of motion by separate, sparse measurements of the proper position and speed relative to landmarks in the surrounding space. Independently and in combination with other navigation tools, the described approach provides high-precision determination of navigation parameters in various driving conditions. The results of field experiments with the model of the proposed system in motion under various conditions are described. The ways of improvement and development of the considered approach are discussed.
