It is difficult to be placed in the position of the laser tracker to meet the requirement of measuring accuracy for the special environment such as the external disassembly and reassembly of a certain type of fork type wing-fuselage docking aircraft. Firstly

this paper presents a direct measurement method based on vision. Secondly

builds the measurement system model

analyzes the key technology of vision measurement system involved

and presents a method of ellipse detection based on arc combination. Finally

through the simulation test of fork type wing-fuselagedocking

verifies the actual feasibility of these method. The experimental results show that the cross axis gap distance measurement precision can reach 0.03mm

and the axis angle measurement accuracy reaches 0.025°

which meets the requirements of actual docking measurement.