Fault-Tolerant Navigation Method for Unmanned Aerial Vehicle Based on Heterogeneous Pseudorange Augmentation

With the increasing application field of unmanned aerial vehicles, the integrity guarantee capability of satellite navigation system is constantly challenged by complex environments. The introduction of multi-source auxiliary information is an effective mean to enhance the availability of satellite navigation. As a method of land-based long-range radio navigation, Loran-C navigation system has good stability and can provide pseudorange auxiliary measurement information in specific areas to assist satellite receiver in fault detection. Aiming at the problems that the protection level provided by satellite navigation alone may not meet the requirements and the accuracy and reliability of fault detection result may reduce in complex environments, this paper proposed a fault-tolerant navigation method for unmanned aerial vehicle based on pseudorange augmentation. This method introduces the augmented pseudorange information of Loran-C system to assist the inertial/Beidou integrated navigation in integrity detection. Considering the difference of pseudorange measurement characteristics between Loran-C system and Beidou navigation system, this paper uses the weighted least square method to overcome heteroscedasticity and establishes the Loran-C/Beidou augmented pseudorange observation model. Based on this model this paper studies the augmented pseudorange system integrity protection level algorithm when introducing the Loran-C information, and constructs the fault detection and system fault-tolerance algorithm on this basis. The simulation results show that, compared with traditional satellite navigation, this method can effectively improve the integrity guarantee level of system and enhance the fault-tolerance ability of the system under the condition of partial limitation of satellite navigation.