Research On Magnetic Guidance For Autonomous Vehicles In Urban Environment

Having the obvious advantages in reliability, magnetic navigation technology has broad application scenarios and has been the most applicable automated vehicle technology. Some of the existing demo applications have demonstrated the feasibility of magnetic navigation. However, in urban environment, the existing magnetic navigation approaches encountered some challenges. The most severe one is that the curvature of the road in urban environment is usually small and even varies violently, which makes the look-down property of magnetic navigated vehicle have heavily influence on its control. The existing magnetic nails’ high precision coordinates map based method can handle these problems, but the map’s acquisition is tedious, and sometimes nails’ coordinates need to be measured one by one through engineering of surveying. Aiming at the deficiencies of the existing methods and the key problems of magnetic navigation in urban environment, this paper make a profound study of magnetic navigation technology.First, the existing magnet localization methods don’t make full use of sensor’s information and the method of magnetic field model curve fitting is non-linear. To handle these deficiencies, this paper proposed the Gaussian curve fitting based approach for the lateral deviation’s calculation, using more sensor’s information and converting non-linear optimization of magnetic field model curve fitting to the least square problem of Gaussian curve fitting and verified mathematically the two curves are equivalent with very high accuracy. What’s more, this paper has proposed the normal model equation for any road whose curvature is integrable, thus provides normal solution for the building of local road model.Second, to overcome the problem that map generation of existing map based methods need high expenditure of time and efforts, the concept of curvature map and its generation algorithm were proposed. The proposed curvature map based approach could get the same performance with the approach based on nails’ high precision coordinates map, but its biggest advantage is its simple map generation process, which only needs the vehicle be driven along the reference trajectory by hand.Finally, to overcome the core issue of the look-down property of magnetic sensor, curvature map based navigation approach was proposed, in which the proposed local road model was used to fit the magnet tracking results as well as the curvature map information to achieve robust information of road ahead and thus preview control was achieved.In experimental section of each chapter, the proposed approaches have been verified using real car’s experimental data. In practical, the approach proposed in this paper performs as well as the approaches based on magnetic nails’ coordinates map. The curvature map using in our approach can be achieved simply and automatically.