Availability Improvement Of RTK-GPS With INS In Harsh Environment

Navigation indicates art to be located in space.It is practiced daily by each of us,for whom it is a question of simply going to its workplace or of being directed in an unknown city.Unconsciously,we reproduce the same approach as the most elaborate systems of positioning.We interpret the furnished information by our directions(sight)using our knowledge a priori of the environment where we move(map,visual cues)to deduce our position from it.The two key steps of the resolution of a problem of navigation are present in this approach.The first phase is carried out by a set of on-board sensors,which take a series of measures indirectly related to the parameters to be estimated and sullied with noise.Then,the estimate of these parameters is realized based on collected measurements and,in a Bayesian context of an a priori model of evolution.The second phase is called filtering.Guidance systems currently used for vehicle navigation are mainly based on the autonomous use of a GPS receiver.These systems still have significant loss of performance when subjected to a perplex environment.To address this problem,several methods proposed such as the integration of GPS and INS systems.However,the utilization of inertial sensors remains low today the main obstacle of these GPS/INS hybrid systems is due to lack of calibration as well as the highly stochastic nature of measurement errors of these sensors.The integration of GPS system with Inertial Navigation System INS are elaborate on several integration strategies,which consist on the architecture adopted to combine the information of each them.Therefore,the Kalman filter is used to merge the GPS and inertial information for each strategy such as the loosely and tightly coupled integration.This thesis is to assess the effectiveness of integration navigation system GPS/INS for robust navigation in challenging environments which it can be encountered in city area,dense forest or going through a tunnel,etc.;to bridging the lack GPS signal and enhance the accuracy of positioning over all the period of navigation.The results obtained demonstrate that the application of this model can significantly improve the stability of navigation solution in severe urban canyon compared to the independent usage of a GPS receiver.It was also shown that the advantage to implement various additional aiding sources and sensors to improve the precision positioning to 60%,essentially during long GPS outage.