| The use of unmanned aerial vehicle(UAV)reconnaissance is an important prerequisitefor winning the informationization war,and has advantages that other reconnaissance methods cannot match.Airborne photoelectric platform as an important payload is considered to be "eyes" of UAV,it integrates machinery,communications,optoelectronics and automation technology,to complete detection,location,tracking and school tasks such as crucial.The structure of the airborne photoelectric platform is the carrier and actuator of the whole photoelectric system.Its overall layout and structure are related to the stability accuracy,response speed and carrying capacity of the platform.The airborne photoelectric platform main structure mainly has two-axis and two-frame,three-axis and three-frame,two-axis and four-frame,etc.Aiming at the advantages and disadvantages of several kinds of structure,a new type of high performance "four-axis and four-frame" structure is proposed,and its principle analysis and finite element analysis are carried out.In the overall scheme design,the 3d model of the platform was established through CATIA software,and the detailed design of the structure was improved by combining with Auto CAD software.The structure of "four-axis and four-frame" is composed of the rotation mechanism and the spherical mechanism.The content and characteristics of structure scheme is analyzed.The main mechanical structures of frame structure,rotation mechanism and spherical mechanism are described in detail.The selection and check work of drive motor,Angle sensor and bearing are completed,and the results show that the selected key components meet the requirements and technical specifications.In the principle analysis of the platform,the structure principle and kinematics analysis of spherical mechanism are mainly carried out.It is proved that the spherical mechanism is a parallel mechanism with 3 degrees of freedom.The relationship between the Angle input of the three axes and spatial position output of the end-effector is obtained.The kinematics equation is derived and the spherical mechanism is fully decoupled and verified by simulation.Furthermore,the jacobian matrix is solved,and the transfer relation is obtained.It is proved that the spherical mechanism has the characteristics of simple input and output,no singular point,completely isotropic,uniform distribution and so on,and the working space of spherical mechanism is basically covered by the MATLAB software.In the finite element analysis,static analysis and fatigue analysis are carried out on the important components of the platform.The significance of finite element method in the structure of airborne photoelectric platform is clarified.,and the principle and implementation steps of finite element method are introduced.By using ANSYS Workbench to analyze thespherical frame and parallel mechanism,the results show that the static characteristics meet the requirements.According to the practical application,the fatigue analysis of the parallel mechanism is carried out.The fatigue under constant amplitude load and random load is obtained,and the analysis results show that the components meet the design requirements.The comprehensive structure design and analysis proves that the "four-axis and four-frame" structure can be used to carry the photoelectric equipment and drive the visual axis to move and maintain the stable function within a certain range.It can also bear the effects of driving force,vibration,acceleration and air resistance,and it has a series of advantages such as light weight,high space utilization,high universality,large scope of vision and good controllability.At the same time,the principle of "four-axis and four-frame" structure can make the platform have the characteristics of fast response,high stability,high working range and easy to control. |
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