Research On The Key Technology Of The U-shaped Parallel Tracking Platform

Parallel tracking platform technology is developed gradually to meet the need of multi-freedom tracking of the moving target. In this paper ,the following key technology of the U-shaped parallel tracking platform, which is of one advection freedom and two revolution freedom, is deeply discussed: topological structure; methods of the visible parameterization design; modeling of the kinematics and the kinetics; auto-control and manual intervention control methods; calibration methods.The key of realizing the optimization design of the device layout is studying the device topological structure, which aims to derive the probable structure meeting the need by building the topological character of the device. According to the single-open-chain topological theory and the topological design principle of the parallel device, the topological character of the parallel device, which can realize the space three freedom movement of parallel device, is deeply studied in this paper and further gives a new plan of the parallel tracking device with U-shaped parallel support layout, namely the U-shaped parallel tracking platform.The optimization design of the device size is realized through the parameterization design method. The mathematical model of the U-shaped parallel tracking platform is built according to the transformation relationship between two coordinate systems. Basing on this model, a visual parameterization design method of the parallel tracking platform is given. Experiments show that, this method can realize the optimization design of the U-shaped parallel tracking platform and be applied to the optimization design of the multi freedom parallel devices.The main aspects of the device dynamic character study are the modeling and analysis of the kinematics and kinetics. The features and application range of the current kinematics and kinetics methods are summarized in this paper. The kinematics modeling method based on the point movement synthesis theory is given and the kinetics model is built using the Kane method.The kinematics and kinetics model of the U-shaped parallel tracking platform are built and the two model realization methods, which are coding and virtual prototype, are analyzed and compared. The virtual prototype technology has higher efficiency among the two methods to achieve the same effect. The kinematics and kinetics character data, which reflects the dynamic character of the U-shaped parallel tracking platform,is got through emulation experiments, which provides the theory support for the later accessory selection of the tracking control system and the system building.The control annulus is an important part in the tracking system design, which directly affects the final tracking result. In this paper, the hardware structure design and system building of the tracking control system is finished firstly according to the gotten emulation experiment data of the kinematics and kinetics. Then according to the target tracking mechanism, the auto-control model of the U-shaped parallel tracking platform is built, the auto-control experiments are done and its validity is validated. The feature and drawback of the current manual control methods are analyzed and a manual intervention control method with two-axis control stick is given, which is more interactive. The concerted movement and control are realized between the tracking platform and hand through using spatial geometrical relationship to get the control information and combining the control stick swinging direction and tracking platform moving direction to build the mapping relation.It is the calibration of the parallel tracking platform to realize its high accuracy tracking and positioning. The repeatability accuracy of the U-shaped parallel tracking platform is validated in this paper by two-CCD compound measurement.