Study On Position-pose Measurement Method And Application Using Multiple Collimated Beams

With the development of modern science and technology, position and pose measurements of the workpiece, part or target object are often required. For example, the interior orientation elements (principal point, principal distance and camera angle) of the three line array CCDs camera are key characteristics for high precision satellite photography. The position and pose of the camera’s detectors and lenses will change on orbit because of the satellite launch vibration, weight loss, temperature change and other effects, thus causing changes of the interior orientation elements. It has become one of the major limitations to improve the accuracy of the photogrammetry. On-orbit monitoring the change of the interior orientation elements is an ideal solution to this problem. However, the position and pose change of one detector or one lens could lead to comprehensive changes of many parameters and traditional single-parameter measurement method is not competent. So method and technique for simultaneously measuring multi-characteristics and multi-degree-of-freedoms have become a key research direction and technical difficulty in many fields such as aerospace, aviation, machinery, instruments and etc.In this paper, on the basis of comprehensive analyses of relevant researches at home and abroad, the multi-channel LED collimating technique based on the optical switch to obtain high precision collimated light reference was studied firstly. Then, a simple four-degree-of-freedoms (4DOFs) and a6DOFs method for simultaneously measuring the position and pose parameters were proposed. The corresponding measurement system was built and the experiment research was conducted, which verified the effectiveness of proposed measurement methods. Finally, the application of position-pose measurement technology in the aerospace mapping field was carried on and an on-orbit monitoring method for interior orientation elements of the mapping camera was proposed. The monitoring system was developed, and characterization testing research was made, which verified the feasibility and effectiveness of this method and system.In summary, the mainly tasks and innovative achievements of this paper are as follows:1. A method to obtain multi-collimated beams based on combination of a single-mode fiber LED and an optical switch was proposed and the corresponding alignment system was built. The experimental results show that the collimated beams have the characteristics of high stability and good homology, that it can be used as the collimated light references for multi-degree-of-freedoms measurement system; though a quasi-common path method, the influence of air turbulence on collimation measurements can be further decreased.2. A4DOFs measurement method based on dual collimated beams and a6DOFs method based on three collimated beams were proposed. Mathematical model was constructed and crosstalk of different errors was simulated. The experimental system was built on the basis of simulation analyses. The relevant tests and error analyses were accomplished and the feasibility of these two methods were verified.3. Based on the multi-collimated beams, an on-orbit monitoring method for the interior orientation elements of the three-line array CCDs space mapping camera was proposed. Containing all36degree of freedoms, a mathematical model of the camera system was constructed. Based on the simulation and analysis, five key degree of freedoms influencing the camera angle were derived, thus making on-orbit monitoring be possible. Then an on-orbit monitoring system for the interior orientation elements of the mapping camera based on the multi-collimated beams was designed and the simulation test systems were built. The feasibility and effectiveness of the method were verified by the experimental results.