考虑磨损后含间隙指向机构运动特性

Motion characteristics of pointing mechanism with clearance in consideration of wear

为了提高空间指向机构磨损寿命的预测精度,克服传统静态磨损寿命预测的缺陷,计及间隙、摩擦磨损耦合因素,以实现机构关节动态磨损的精确预测,并对综合考虑间隙、摩擦磨损等因素的空间二维指向机构动力学问题和磨损问题进行了研究。采用牛顿-欧拉法,将间隙变量嵌入动力学模型,构建含间隙二维指向机构的动力学模型。基于Archards磨损模型,找到运动副接触面不同位置处的磨损深度,重构运动副表面形貌,并对磨损前后含间隙指向机构的动态特性进行分析,得到了关节处接触碰撞力和切向摩擦力的变化规律;采用动态拟合变量法和离散处理法分别对含间隙运动副内部间隙与接触力间、运行时间与相对滑移速度间的对应关系进行拟合,并建立了动态磨损数学模型;进一步预测了二维指向机构在跟踪模式、调姿模式下的运行时间分别为12 591.92h、764.44h。研究工作为二维指向机构的本体设计、制造与应用奠定基础。

For the accurate prediction of the joint dynamic wear,the coupling factors of clearance,friction and abrasion were considered.The dynamic problems and abrasion problems of the two-dimensional space pointing mechanism were studied,which considered the factors of clearance,friction and abrasion.Using the Newton Euler′s law,the dynamic model of the two-dimensional space pointing mechanism with clearance was constructed by embedding the clearance variables.Based on the Archards wear model,by finding the wear depth at different positions of the moving contact surface and reconstructing the surface morphology of the kinematic pair,the dynamic characteristics of the pointing mechanism with clearance were analyzed in the process of wear,and the change laws of the contact collision force and the tangent friction force at the joints were obtained;the dynamic fitting variables method and the discrete processing method were used to fit the correspondences between the clearance and contact force,and the running time and the relative slip velocity of the kinematic pair with clearance,and the dynamic wear mathematical model was established;furthermore,the predicted service lives of the two-dimensional pointing mechanism are 12 591.92 hours and 764.44 hours under the tracking mode and the attitude adjustment mode.The work in this thesis provided the theoretical base for the ontology design,manufacture and application of the two-dimensional pointing mechanism.