The Reserch Of Dynamic Performance Of Two-dimensional Pointing Mechanism With Clearance Space And The Abrasion Life Prediction Of Joint

With the continuous development of precision mechanical engineering and aerospace engineering,the mechanical system accuracy,efficiency,reliability and service life requirements are getting higher and higher.The mechanism is connected by the kinematic pair,At present,due to the influence of processing and process factors,there must be clearance space among the kinematic pairs.The clearance space will cause the actual trajectory of the mechanism to coincide with the theoretical trajectory and will reduce the accuracy of the end effector.Therefore it’s necessary to consider the dynamics of the joint clearan and the internal abrasion.In this paper,the spatial two-dimensional pointing mechanism,as the research object,is researched in dynamic characteristics and abrasion characteristics.First of all,dynamic model of two-dimension pointing mechanism without clearance is established by Newton Euler method.Considering the clearance factor,the clearance is embedded into the ideal dynamic model to obtain the dynamic model of the two dimensional pointing mechanism with clearance.And the nonlinear spring damping model is used to represent the contact impact force in a revolute pair with clearance.The improved Kulun friction model is used to describe the tangential friction force.Finally,the relationship between the contact impact force and the friction force at the joint and the different forces at the joint of the dynamic model are established.The dynamics model is used to compile the multi-body system dynamics calculation algorithm is written by Matlab software using dynamic model.And the contact force within the revolute joint and the relative motion of the elements in different gravity environment,different clearance and different friction coefficients are studied as the two dimensional pointing mechanism is running at constant speed.The dynamic characteristics of a two dimensional pointing mechanism with clearances are studied thoroughly as the driving parameters are given.The abrasion depth at different positions on the contact surface of the kinematic pair is calculated by establishing dynamic calculation model of Archards abrasion to reconstruct the surface topography of the kinematic pair.The new dynamic parameters are obtained and substituted into the mechanism dynamics model,and then the dynamic characteristics of the mechanism are analyzed.Finally,the prediction method of abrasion life is obtained by theoretical analysis and an example is analyzed.Based on the established prediction model of abrasion life,the Matlab recursive algorithm is established to calculate the times of operation when the failure threshold is reached.The numerical solution of the abrasion life is obtained after transformation.Finally the abrasion life of two-dimensional pointing mechanism of satellite antenna is predicted.