Research On Key Technology Of Indoor And Outdoor Positioning Using Integrated BDS/INS Navigation

In recent years, with the rapid development of wireless communication technology and the widespread popularity of mobile intelligent terminals, the needs of indoor and outdoor positioning are increasingly urgent. And the accelerated process of urbanization in China has led to the increasing of domestic large buildings and bridges. Beidou Satellite Positioning System(BDS) can provides the high accuracy of positioning output in open environment, but it can’t achieve effective positioning in indoor or urban canyon environment because of the satellite signal will be blocked by the large buildings or trigger multi-path effect. To meet the needs of users, guaranteeing continuous and accurate indoor and outdoor positioning is necessary.The Inertial Navigation System (INS) can be independent of external signals, has a high precision in short time and continuous output, but it suffers from time-dependent error growth, while the BDS provides a high accuracy of positioning and error does not accumulate, but it can’t work when the satellite signal fails, its output information is not continuous and susceptible to interference. BDS/INS integrated positioning system can achieve complementary advantages.In this paper, we firstly introduce the positioning principle, data processing and error sources of the two subsystems in the integrated navigation system. Then, we study the key technologies in the BDS/INS integrated navigation system deeply, such as the filtering algorithms and correction methods. The state equation and the measurement equation in loose integration are deduced in detail. This paper focuses on the problem of suppressing the error accumulation of INS when the satellite signal is lost for a long time. In this paper, we propose that the velocity given by odometer can be used as the external observation based on the non-holonomic constraints to suppress the INS error and improve the accuracy of positioning. And we put forward a dynamic estimation algorithm of step size, using the accurate data which is outputted by the satellite to train the parameters of the step size model in outdoor environment, while using the step frequency and average of the acceleration within one step to provide the accuracy of the positioning in indoor environment.When the satellite signals can’t be used for effectively positioning,we can use pedometer and gyroscope to carry out dead reckoning.Otherwise, we can using integrated BDS/DR navigation.The feasibility of the loose navigation system implemented in this paper is verified in actual scene and the simulation results in Matlab environment. It is shown that the algorithms proposed in this paper can effectively restrain the IMU’s cumulative error when satellite signal is outage.