Terrain aided inertial navigation for precise planetary landing

Abstract

This thesis proposes a navigation system architecture which consists of Inertial Navigation System (INS) with the optical sensor for precise planetary landing. In the future exploration mission beyond the Earth, high-accuracy navigation information is required to complete the mission. The well-known navigation system, INS, can provide position, velocity, and attitude by integrating the output of Inertial Measurement Unit (IMU); however, the accumulated error results in incorrect navigation information after several times. To overcome the navigation error caused by INS drift, INS combined with other sensors is introduced. By comparing the measured terrain data with on-board reference map or terrain profiles, the navigation error can be compensated. This system is called Terrain Aided Inertial Navigation (TAIN). This thesis develops TAIN using the camera as the optical sensor. Image processing is conducted to extract the feature points between the measured terrain data and on-board implemented terrain information. The navigation system employed Iterated Extended Kalman Filter (IEKF) can compensate the navigation error and provide precise navigation information compared to the single INS. Simulation proves the feasibility of integration to accomplish the precise planetary landing. This navigation system can be applied to implement the whole system coupled with guidance and control law. Suboptimal covariance analysis can examine the performance of the designed filter. Based on the output of this analysis, the developer can evaluate and verify the implemented system whether it can meet the system requirement or not.