Relative Measurement Based On Optical Navigation Technology Research

With the increasing requirement for the joint operation in modern warfare, the relative navigation technique has been developed continuously. Unlike absolute navigation, relative navigation works out the coordinates of the carrier in the same relative coordinate frame or network system based on the measurements of relative positions. However, this position in the absolute coordinate frame, or the WGS-84 coordinate frame, is not precise, due to the accumulation of Inertial Navigation System (INS) errors. During the relative navigation, it is necessary to utilize other navigation systems to acquire more accurate estimates of positions of carriers in the WGS-84 coordinate frame, and accordingly, achieve autonomous navigation.In this thesis, a navigation solution based on landmark imaging is proposed to improve the accuracy of the navigation system.Firstly, a method of correcting INS errors based on the landmark image messages is presented. Using the landmark imaging system in the onboard optical-electronic platform, the position of the aircraft can be worked out. Then the flight path errors of the aircraft can be calculated, which can be used to correct the INS errors.Secondly, regarding this INS error correction scheme, the performance requirement for the optical measurement system is studied in order to achieve some specific accuracy of correction. The result provides a theoretical basis to design and develop such optical measurement systems.Finally, navigation parameter estimation by using serial images is discussed. A two-dimensional motion model is defined to describe the tracking points and the PDAF algorithm is employed to obtain the estimate of the state vector. The toke selection algorithm and criterion are summarized. Based on serial images, a mathematical model of navigation parameter estimation is established by using IEKF.Simulation studies are carried out and the results show that the system can efficiently decrease the INS errors caused by the gyroscopes and accelerometers, greatly increase the accuracy of the navigation parameters. The system can achieve accurate passive localization, and accordingly, calculate relative navigation parameters with respect to the absolute coordinate frame.