Abstract: Firstly，the simulator was introduced to simulate the procedure of spacecraft rendezvous and docking. Then, attitude kinematics and pose from orthography and scaling with iterations (POSIT) algorithms were described. Secondly, extended Kalman filter(EKF) was used to integrate the data from two sensors so as to determine the relative attitude and gyro biases.  Thirdly, a nonlinear observer was presented to overcome the difficulty of tuning the parameters of EKF and avoid solving the inverse of matrix during EKF updating. Finally, experiments were carried out upon 4-DOF air-bearing simulators. The experimental results validate the availability and precision of the proposed methods. 

Key words: Rendezvous and docking, Air-bearing simulator, Vision-aided attitude determination, Extended Kalman filter, Nonlinear observer, Spacecraft