超机动载荷下AVEN机构静态奇异位置动力稳定性及其改善

Dynamic stability of AVEN at its singularity configuration is a key for the fourth-generation combat aircraft with AVEN surviving in the super maneuverable fighting. Continuous our pervious studies supported by NSFC, this study mainly focuses on solving the problem of the dynamic stability of AVEN at its singular configurations under super maneuverable loads and improvements, including: the influences of the elastic deformations of the platform and the components on the transformation of singular configurations, and a robust design method of fault-tolerant joint clearances relative to the elastic deformations; the dynamic stability condition of the singular configurations of 3SPS-3PRS parallel mechanism, for example, corresponding to Grassmann geometric relationships, and one of the singularity configuration of RSRR kinematic chain in AVEN corresponding to the components collinear or coincident configurations. By using a fewer variables to setting up the elastic dynamic equation, dimensional reduction of the dynamic model, and the universal unfolding, the dynamic stability of AVEN at its static singular configurations under ultra maneuvering loads will be studied then, and the analytical expression of the dynamic stability including the input kinematic parameters, ultra maneuvering loads and elastic dynamic responses of RSRR will be deduced. Based on this expression, the input kinematic parameters planning and design method to improving the dynamic stability of AVEN at its singularity will be presented. This study has definite merits in eliminating the negative effects of singularity on the parallel mechanism, and enhancing the survivability of the fourth-generation combat aircraft in air fighting.

AVEN机构奇异构型的动力稳定性是制约四代机空中超机动格斗生存的关键。在前期研究基础上，本课题重点解决超机动载荷作用下AVEN机构奇异构型的动力稳定性及其改善问题，包括：动平台及构件弹性变形对奇异构型转迁的影响，给出容错弹性变形致奇异构型转迁的运动副间隙稳健设计方法；以3SPS-3PRS并联机构为例，研究符合Grassmann线丛几何关系奇异构型的动力稳定条件；以RSRR运动链为对象，研究构件共线或重合闭环机构奇异构型的动力稳定性。通过少变量弹性动力学方程建模、方程降维、普适开折等措施，研究超机动载荷作用下AVEN机构静态奇异位置的动力稳定性，得到包含输入动力学参数、超机动载荷及弹性动力响应的动力稳定性方程，依此给出改善AVEN机构动力稳定性的输入动力学参数规划设计方法。该研究对于消除运动奇异对并联机构的消极影响，提高四代机空中格斗生存能力，具有重要的理论价值与国防应用价值。

隐藏在轴对称矢量喷管内部的运动奇异性，给含推力矢量发动机五代先进战机的飞行安全带来严重的安全隐患，是制约轴对称矢量喷管列装的关键障碍。为提高含推力矢量发动机先进战机飞行的安全性，课题组在前期研究的基础上，在本项国家自然科学基金课题资助下，重点解决超机动载荷作用下AVEN机构奇异构型的动力稳定性及其改善问题。根据李雅普诺夫近似稳定判据，基于Gerschgorin圆定理与Hurwitz判据，研究了3-RPR并联机构运动稳定性与负载能力对应的动平台角速率和质心速度分布；从弹性结构动力学角度出发，系统研究了符合线丛几何关系AVEN机构奇异构型及动力稳定条件；分析了气动载荷和超机动载荷联合作用下，RSRR 运动链各构件的弹性变形与动平台位姿误差补偿问题；建立了包含超机动载荷作用的AVEN机构动力学方程，通过对动力学方程降维、普适开折、构建规范型等措施，给出超机动载荷作用下并联机构静态奇异位置的动力稳定条件，得到包含输入动力学参数、超机动载荷及弹性动力响应的动力稳定性方程；依此，给出改善并联机构动力稳定性的输入动力学参数规划设计方法，实现了课题预期研究目标。本课题研究对于提升我国AVEN的运动可靠性，加速我国AVEN列装步伐，使我国先进战机成为优先配备轴对称矢量喷管技术的高性能、超机动的战区优势五代战机，具有重要的理论价值与重大的国防应用价值。