Topology Synthesis,Parameter Design And Dynamic Analysis Of Parallel Tracking Mechanism With Varied Axes

Tracking mechanism is a significant component of the inter-satellite link antenna of Tracking and Data Relay Satellite,which actuates the antenna to realize real-time tracking of spacecrafts on medium and low orbit.Driven by the requirements of the national aerospace engineering,the topology synthesis of parallel tracking mechanism with varied axes,parameter optimization considering multiple performance requirements and parameter uncertainty,kinematic and dynamic analysis in flying working mode are carried out with the help of the modern mathematical tools as Clifford algebra and screw theory.The main research achievements are as follows.(1)Driven by the large workspace requirement of the inter-satellite link antenna of Tracking and Data Relay Satellite,the topology synthesis of parallel tracking mechanism with varied axes is carried out.Based on Clifford algebra,the finite motions of the moving platform are modeled algebraically by analyzing the internal relationship between its independent and dependent motion parameters in the first place.According to the motion matching principle between the moving platform and the open-loop limbs,the finite motions of the available open-loop limbs are obtained.Then the topology structures of the open-loop limbs are generated on the basis of the finite motion correspondence between the open-loop limbs and the articulated joints.Finally,the assembly principles among the available open-loop limbs are defined by analyzing the number and combination of the available open-loop limbs,and various topology structures of parallel tracking mechanism with varied axes are synthesized.(2)In order to meet the multiple performance requirements of the inter-satellite link antenna of Tracking and Data Relay Satellite,and consider the effect of parameter uncertainty on the performance of mechanism,the multi-objective optimization of multi-parameter considering parameter uncertainty is studied.The kinematic and static analysis of parallel tracking mechanism with varied axes are carried out in the first place,and four indexes in terms of the maximum circumferential angle,virtual power transmissibility,instantaneous deformation energy and mass are established as performance evaluation indexes of the mechanism.Then the influence of the parameter uncertainty on the performance is analyzed,and the mean value and relative proportion are defined as its evaluation indexes.Afterwards,the analytical mapping models between the mean values of the performance evaluation indexes considering the parameter uncertainty with the design variables,including dimensional and sectional parameters,are established.Finally,the Pareto frontier is obtained by particle swarm optimization,and the optimal solution is selected by evaluating the cooperation degree of objectives.Then the dimensional and sectional parameters of parallel tracking mechanism with varied axes are optimal designed towards multiple objectives with its parameter uncertainty considered.(3)Considering the service environment of the inter-satellite link antenna of Tracking and Data Relay Satellite,the kinematic and dynamic analysis of parallel tracking mechanism with varied axes in flying working mode is analyzed.Firstly,the kinematics of parallel tracking mechanism with varied axes in flying working mode is studied on the basis of the conservation of mass and the conservation of momentum theorem,and the relationships between the position,velocity and acceleration of the moveable parts with the output motions of the mechanism are obtained.Secondly,the dynamic analysis of parallel tracking mechanism with varied axes in flying working mode is carried out,and the mapping model between the actuated torques and the kinematic parameters of the moveable parts is established.Thirdly,the typical motions of the mechanism in flying working mode are simulated by software,and the effectiveness of the mapping model of the actuated torques is verified by comparing the results of simulation with the torques calculated by the mapping model.Based on this mapping model of the actuated torques,the trajectory planning of parallel tracking mechanism with varied axes in flying working mode is realized.The aforementioned research achievements contribute to the development of the physical prototype of parallel tracking mechanism with excellent comprehensive performance,and lay a foundation for accurate tracking and control strategy in flying working mode.Therefore,it has important scientific significance and application value.