Angular Shift Calibration for Rudders Based on Monocular Vision

A calibrating method was put forward based on computer monocular vision for the angular displacement sensors of aileron,flap,jaw rudder and elevator,etc,rotating around a fixed axis.The pictures of the double-circle target fixed on a jaw rudder surface and parallel to its axis were taken by a stationary digital camera.The coordinates of four characteristic points were found out by digital image processing.Analytical solution of the double-circle's normal direction cosine was obtained according to perspective projection principle without calibrating camera parameters,then the relative direction of the double-circle's normal was found besides relative positions of the circles' centers.The rudder's angular shift can be expressed with the parameters above.Simulation results show that the calibration is a simple and real-time process and can also be used to measure rendezvous and docking spacecrafts' relative positions and attitude parameters in real time.