An autonomous optical navigation and guidance for soft landing on asteroids

The autonomous optical navigation and guidance algorithm for soft landing on asteroids is presented. First, the probe position relative to targeted asteroid is acquired from the image coordinates of three selected feature points (FPs) on the asteroid surface obtained by using an optical navigation camera and the distances from the probe to each FP measured using a laser range finder. And the real-time probe orbit is determined by using unscented Kalman filter instead of extended Kalman filter to improve the navigation accuracy. Second, the desired descent altitude and velocity to satisfy the requirements of soft landing on asteroids is planned. The variable structure control is then used to design the tracking control law to ensure the fast and accurate response and robustness of guidance law. Finally, the navigation and guidance algorithm is formed and the effectiveness of algorithm is verified by numerical simulations.