Vision-Based Rapid Target Tracking Method for Trajectories Estimation and Actuator Parameter Uncertainties for Asteroid Flyby Problem

Flyby imaging has attracted attention as a method for small body exploration and the requirement for an accurate target tracking system becomes higher for the mission quality. A relative trajectory that is either designed or estimated offline contains uncertainties, and they cause errors in the targeting profile generated for imaging missions. Online relative trajectory parameter estimation is required to obtain high-quality imaging, and visual-based tracking systems are popular for estimating the relative trajectory. In addition to the uncertainties in the measured or estimated relative parameters of trajectories, the high relative velocity between the spacecraft and the asteroid, as well as the actuator driving characteristics have a negative impact on asteroid tracking. To overcome the problems, this paper proposes a control system with two degrees of freedom, which includes a vision-based feedback controller and feedforward controller. The feedforward controller contains two compensators: the first utilizes a real-time vision-based relative trajectory estimator and predicts the future relative trajectory from the results of the estimation, and the other compensates for the actuator characteristics. The applicability of the proposed control system is discussed by using a case study based on numerical simulation. The results show the effectiveness of the proposed concept.