Application of Nonlinear Smoothing to Integrated GPS/INS Navigation System

The application of smoothing in the integrated navigation system of 4S-Van is considered. 4S-Van is a mobile mapping system, which provides the position information of various objects on the road. For navigation purpose, it has various sensors such as an inertial measurement unit, a GPS receiver and an odometer. It is also equipped with CCD cameras, laser scanners and video cameras, for mapping purpose. The navigation system of 4S-Van is based on an inertial navigation system, which is aided by GPS and the odometer. Because it can adopt a post-processing method for more accurate and reliable results, the nonlinear smoothing is applied. The nonlinear smoothing, which consists of a forward filter, a backward filter and a smoother, is implemented. For the forward filter, the extended Kalman filter is designed, and for the backward filter, the linearized Kalman filter is constituted. In the smoothing stage, the results of two filters are combined. The algorithm is applied to experimental data and the obtained result demonstrates the effectiveness and good performance of the nonlinear smoothing.