The Study On Dynamics Characteristics Of Long-span Linear Motion Mechanism Driven By Synchronous Belt

Using long-span linear motion mechanism driven by synchronous belt as the linear motion mechanism for a novel three-degree-of-freedom optical testing target to meet the accuracy requirements in the large stroke and high speed conditions.In this thesis,aiming at the requirements of vibration reduction and improvement of dynamic motion accuracy of linear motion mechanism driven by synchronous belt,the influencing factors of the vibration and dynamic motion error of the linear motion mechanism driven by synchronous belt during the working process are systematically analyzed by means of theoretical analysis,simulation and experiment analysis.The main research work is as follows:Based on the requirements of a novel three-degree-of-freedom optical testing target for the motion stability of its linear motion mechanism,the lateral vibration characteristics of the linear motion mechanism driven by synchronous belt were analyzed by theoretical analysis and simulation.Firstly,the synchronous belt drive system is simplified as the chord and beam model in the vibration system.Based on the equilibrium equations of force and moment,the motion differential equations of transverse vibration of the belt are established,and according to different boundary conditions,the natural frequency of transverse vibration of static and dynamic transmission system is solved.Based on the theory of flexible multi-body system dynamics,a flexible multi-body dynamics model of belt drive was established using rigid finite element method.Then the finite element analysis model of the linear motion mechanism driven by synchronous belt is established in the finite element analysis software HyperMesh / OptiStruct.The pre-stressed modal simulation analysis is carried out,the natural frequency of transverse vibration of the belt drive system under pre stressed condition is obtained.And the influence of initial pre-tightening on the natural frequency of the system is analyzed.Finally,the rigid-flexible coupled multi-body system model of the linear motion mechanism driven by synchronous belt was established in the multi-body dynamics analysis software RecurDyn,and a flexible multi-body dynamics simulation analysis is performed on it,and the influence of initial pre-tightening force and driving wheel speed on the frequency and amplitude of the transverse vibration of the belt drive system was studied.Based on the requirements of a novel three-degree-of-freedom optical testing target for the dynamic motion accuracy of its linear motion mechanism,the dynamic motion error of the linear motion mechanism driven by synchronous belt was analyzed using theoretical analysis,simulation and experimental verification methods.First of all,according to the characteristics of the novel three-degree-of-freedom optical testing target and the measured optical theodolite,the dynamic motion accuracy requirements of the linear motion mechanism driven by synchronous belt are calculated.Based on the influence of the elastic deformation of the belt,the polygon effect and the eccentricity of the pulleys on motion error of the linear motion mechanism driven by synchronous belt,a quantitative expression of the dynamic movement error and the structural parameters of the linear motion mechanism driven by synchronous belt is established.Then using the rigid-flexible coupling multi-body system model of the linear motion mechanism driven by synchronous belt,the dynamic motion error of the linear motion mechanism driven by synchronous belt is simulated by multi-body dynamics.The main factors leading to the linear motion error of the load during the linear motion and the influence of initial tension,load acceleration and mass on the linear motion error were analyzed.Finally,a linear displacement sensor is used to analyze the dynamic precision of the linear motion mechanism driven by synchronous belt of the three-degree-of-freedom optical detection target.The influence of the change of the driving pulley acceleration on the motion error of the linear motion mechanism driven by synchronous belt is analyzed,and the simulation analysis is verified.