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  • A Prototype of Microgravity Facility Operated by Linear Motors: Motion Plan and Control

    Paper number

    IAC-19,A2,5,11,x50594

    Author

    Dr. Yuman Li, China, University of Chinese Academy of Sciences; Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences

    Coauthor

    Dr. Wenbo Dong, China, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences

    Coauthor

    Mr. Zhang Shancong, China, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences

    Coauthor

    Dr. Zhang Yongkang, China, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences

    Year

    2019

    Abstract
    As human beings make constant progress in space exploration, the demands for simulating microgravity and partial gravity on the ground are expanding. The mainstream ground-based microgravity facilities are drop towers and drop shafts, such as ZARM, Zero-g, NLMC and MGLAB. Such facilities provide microgravity conditions by dropping a capsule, which would perform free-fall motion. Mechanical shock-buffers are equipped to decelerate and recycle the capsules in the facilities, which have two obvious shortcomings. Firstly, the brake decelerations of mechanical buffers, which are usually more than 10 g, are usually harmful to the experiment payload. Secondly, the uncontrollability of recovery takes time for experiment preparation.\\
    Here a novel facility operated by linear-motor with acceleration-controllable abilities is proposed. It can simulate weightlessness and other partial gravity conditions with similar performance with drop tower. In this facility, linear motors are used to provide electromagnetic thrust and accelerate upward and then decouple the carrier. The carrier will do free-fall motion along a vertical parabolic flight, during which the carrier has microgravity conditions. Microgravity experiments can be carried out inside, which could be vacuumized when needed.\\
    This paper emphases the motion planning and control: Firstly, the motion curves are designed; secondly, the overshoot is considered during the motion; thirdly, the capsule is controlled to avoid the contact between the inner-capsule and the outer-capsule. Traditional S-curve-velocity motion plan is frequently adopted in machine tool to avoid the capsule from impact, overshoot and oscillation. In this paper, a novel S-curve motion plan is proposed in order to adapt to motor thrust characteristics better and has better control precision.\\
    A prototype equipped with 3-meters linear motor is built to test the assumptions. The test results verify the feasibility of using linear motors to create microgravity and partial gravity environment. The results show that the dual-pass microgravity duration with short interval is realized. The overshoot and vibration can be reduced by using S-curve motion plan.
    Abstract document

    IAC-19,A2,5,11,x50594.brief.pdf

    Manuscript document

    IAC-19,A2,5,11,x50594.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.