Research On A Novel Pointing Platform System Based On Spherical Gear Transmission

The technology of pointing platform is used widely in spaceflight and militaryindustry, and it attracts more and more attention of technologists. With the rapidlydevelopment of our project of exploring the deep space, laser communication, and laserweapons, the technology requirement for pointing platform system is improved.Restricted by the structure, driver motor, sensors, and the technology level, pointingplatform can not meet the requirements very well. Consequently, it is important toresearch on the novel pointing platform system with big load capability, precisionpointing capability, and small volume and weight.This paper is supported by the general equipement department pre research project“research on the novel pointing mechanism based on spherical gears”. After thesummarization of the existent pointing platform, a novel pointing platform designationis presented in this paper. Based on this designation, the structure designation andanalysis, kinematics and dynamics modeling, pointing error analysis, and movementcontrol system are discussed in this paper. The main contents are as follows:1. A novel pointing platform designation based on spherical gear transmission ispresented in this paper. Summarize the charicteristics of the existent pointing platformsand indicate the limitation of them. Then the desination of a novel pointing platform ispresented: the form of two stages, macro and micro pointing platform, is adopted, thespherical gear transmission and XY axis structure are adopted to design the macropointing platform, and the flexure hinge transmission is adopted to design the micropointing platform. The spherical gear and the dish spring are designed and analyzed.The flxure hing designation is improved, its compliance and rotate precison areanalyzed and verified through finite element analysis, and its performance is simulatednumerically. Based on the analysis of the flexure hinge, the flexure hinge with tworotate dimensions and the micro pointing platform are designed.2. Kinematics model and dynamics model of the novel pointing platform areestablished in this paper. Based on the analysis of the spherical gear transmission andthe XY axis structure, the kinematics model of macro pointing platform is established,the dynamics model is also established with Lagrange equation method, and the modelsare verified through simulation analysis. After several simplifications, the kinematicsmodel of the micro pointing platform is established, its dynamics model is alsoestablished with the Lagrange equation method, and the models are verified throughsimulation analysis.3. The error of the novel pointing platform is analyzed in this paper. The sources oferrors are discussed. Based on multibody kinematics method and the kinematics modelestablished, the error model of the pointing platform is established. To improve the precison of the pointing platform, elastic deformations of some parts are analyzed.Based on the error model of the pointing platform, the error is calculated, the errorparameters are recognized with the least squre method, and the result is verified throughsimulation analysis.4. The movement control system is established in this paper. The layeredcontrolsystem scheme is presented, and the designation of the hardware and software isindicated. Based on the dynamics model, the control model of the system is deduced.Considering the error model established in this paper and the nonlinear and strongcoupling characteristics of the system, the PID dismiss-coupling controller with BPneural network including error compensation is presented, and it is verified throughcontrol system simulation analysis.5. Several testing novel pointing platforms are constructed, and several tests areconducted. Four different testing pointing platforms are established and compared withthe structure and the driver form to choose the best desination. Based on the bestdesignation, the pointing platform is tested and then analyzed. The theoretic conclusionsdeduced in this paper and some requirements for the pointing platform are verified.