6-DOF Posture Adjustment Mechanism And Application In Space Deployable Membrane Imager

With the increasing imaging requirements for space-to-Earth orbit observations,high-resolution,high-rigidity,and large-aperture space membrane imagers will play an irreplaceable role.In this paper,we focus on the imaging requirements of Earth observation,and carry out detailed design,analysis and ground prototype development of six-DOF posture adjustment mechanism.In addition,the application of the posture adjustment mechanism in space membrane imagers was carried out,and carrying out mechanical analysis,the adjustment accuracy and scope of the position and posture of space membrane imagers.According to the design requirements of the posture adjustment mechanism,the configuration is optimized and the Stewart mechanism is selected as the basic configuration,and the six-DOF posture adjustment mechanism is designed in detail.Based on the Newton iteration method,the positive kinematics solution of the posture adjustment mechanism is solved.Based on the first-order and second-order influence coefficient matrix methods of the posture adjustment mechanism,the speed and acceleration of the platform on the posture adjustment mechanism is solved and compared with the differential method.Kinematic simulation of posture adjustment mechanism is carried out by using ADAMS software.Using the Monte Carlo method,reachable workspace,the positioning posture workingspace and the complete workingspace of posture adjustment mechanism were solved,which verifying that the mechanism model meets the design requirements of the adjustment range.Considering the bearing clearance and the machining size error,an error model of the six-DOF posture adjustment mechanism is established,and based on the engineering parameters,the platform error distribution on the posture adjustment mechanism is calculated.The pose error calibration model was constructed based on the puter residual equation,and the structural parameter calibration formula of the posture adjustment mechanism was deduced according to the least squares method.The relationship between the external load of the posture adjustment mechanism and the force of the putter is established,and the change of the force of the putter under the load of the upper platform during the motion process is calculated.According to the Lagrangian equation,a dynamic model of posture adjustment mechanism is constructed,and the change of putter force is calculated.Ground principle prototype of posture adjustment mechanism was developed to verify the posture adjustment function of posture adjustment mechanism.Repeated deployment accuracy test and movement accuracy test of the posture adjustment mechanism were verified,and the correctness of the error model was verified.The static stiffness test was performed.These designs and analyses provide theoretical support for the design of on-orbit posture adjustment mechanisms.Based on the articulated truss extension arm,a screw-driven extension support structure system was proposed.The inverted-cone space membrane imager with the main mirror and extension arm system deployed simultaneously was designed.A stiffness equivalent model is established for the extended support structure system,and the relationship between the stiffness of the space membrane imager and the structural parameters of the extended arm is deduced.Analyze the influence of the posture adjustment mechanism and the extension arm size parameters on the first six-order frequency of the space membrane imager.The posture adjustment mechanism is applied to the main mirror adjustment of the space membrane imager,and the adjustment accuracy and adjustment range are analyzed.