Research On Distributed Cooperative Localization Technology Of Multi-UAVs Based On GNSS/UWB

Compared with single-UAV,multi-UAVs collaborative operations can complete richer and more complex tasks.Position as the key information necessary for UAV navigation and control,its accuracy and reliability are very important for multi-UAVs collaborative operations.In multi-UAVs system,in addition to the traditional GNSS observation information,we can also use the relative observation information between the UAVs,such as the relative distance observation information,so as to realize the cooperative localization between UAVs.In this paper,a distributed cooperative localization method based on GNSS/UWB is designed around the problem of solving position information among multi-UAV.In this method,Ultra Wide Band(UWB)technology is used to achieve high-precision relative distance measurement between UAVs.In addition,ZigBee communication technology is also used to exchange and share information between UVAs,and then fusing the GNSS and the relative distance observation information to realize cooperative localization.Robust estimation is also introduced in the data fusion estimation,so that the reliability if the fusion estimation result is guaranteed.The main contents of this paper are as follows:(1)Aiming at the problem of cooperative localization of multi-UAVs,this paper establishes a distributed data fusion framework based on the factor graph theory.In this framework,message transmission and reception will be introduced to achieve information sharing,and then uses the Sum-Product Algorithm to calculate the marginal distribution of UAV node information,and finally uses the Minimum Mean Square Error(MMSE)estimator to estimate the state of UAV.(2)In order to ensure the reliability of the estimation results,this method introduces the variance expansion coefficient into each observation,and the divides the observation data into the retention area,expansion area,and elimination area on the basis of the residual error according to the IGG III robust scheme,and then estimates the coefficients.So,the abnormal observation data will be utilized in a reasonable way and improve the robustness of the system.(3)Based on the GNSS/UWB distributed cooperative localization method designed in this paper,developing a hardware experimental platform suitable for UAVs,and uses it to collect real observation experimental data.The data will be used to verify the effectiveness of the algorithm in a real environment.This paper adopts a research method that combines simulation and experiment.Both simulation and experimental results show that the distributed cooperative localization method based on GNSS/UWB designed in this paper has higher localization accuracy than single UAV.In addition,under the condition if abnormal observation data,this method can also correctly estimate the position information of the UAV,thus making the system more robust.