• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2020, Vol. 56 ›› Issue (15): 170-180.doi: 10.3901/JME.2020.15.170

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Dynamic Characteristics of Space Mechanism Considering Friction and Stiffness

HAN Xueyan1,2, LI Fujuan1,2, GAO Zhenhui2, LI Shihua1,2   

  1. 1. Laboratory of Parallel Robot and Mechatronic System of Hebei Province, Yanshan University, Qinhuangdao 066004;
    2. College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004
  • Received:2019-10-22 Revised:2020-03-25 Online:2020-08-05 Published:2020-10-19

Abstract: In order to establish a more accurate contact force model and improve the pointing accuracy and stability of the spatial pointing mechanism, an improved nonlinear normal contact stiffness model considering the friction factor is proposed. Compared with the existing contact force model, a more accurate model based on the modified L-N model is established, and the accuracy of the new contact force model is verified by experiments. Using Newton-Euler method, contact-separation two-state model, modified Coulomb model and new normal contact force stiffness model, the spatial pointing mechanism is taken as the research object, and its dynamic equation is established, and the influences of different working conditions on the dynamic characteristics of spatial pointing mechanism are studied. The research shows that the new contact force model considering the friction factor can describe the contact collision effect of the joint more accurately, and the new model has wider application range; the gap causes a significant oscillation in the dynamic performance of the spatial pointing mechanism, and with the increase of the gap, the oscillation is intensified; the smaller the surface roughness of joint, the larger the initial collision force; the greater the rotational speed, the greater the impact force on the mechanism, and the higher the vibration frequency of the mechanism, the more unstable the operation of the mechanism. The research results enrich the contact force modeling method and provide a theoretical basis for the design and application of high-precision pointing mechanism.

Key words: nonlinear collision force, pointing mechanism, dynamics, surface roughness, friction

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