Stereo Vision based Cabin's 6-dimensional Pose Measurement in Docking Process

Accurate pose (position and attitude) measurement is a key for automatic docking of cabins. In this paper, a stereo vision based cabin's six-dimensional (6D: three translational positions plus three rotational angles) pose measurement method has been proposed. First, the feature points provided by the visual marker pasted on each cabin's outer surfaces are extracted. The three-dimensional translational coordinates of the feature points in the camera coordinate system are obtained by the stereo vision system. Then the coordinate systems of two markers on two cabins are established through the feature points. The two cabins' 6D poses are denoted by two pose matrices calculated from the two markers' coordinate systems. Relative pose between two cabins is obtained through the two pose matrices. The pose measurement method has been verified using a six-degree-of-freedom (DOF) motion platform. Experimental results show that the errors in three translations and three rotations are +/- 0.06 mm out of +/- 5 mm and +/- 0.07 degrees out of +/- 3 degrees, respectively.