Study On The Vibration Isolation Performance Of Stewart Platform With Double-layer Vibration Isolation Legs

Stewart vibration isolation platform is widely used for multi-dimensional vibration isolation.Under passive control,the structure of the legs considerably influence the multi-dimensional vibration isolation performance of the platform.Therefore,designing a reasonable leg structure is an important way to improve the vibration isolation performance of a passive Stewart vibration isolation platform.In this study,the double-layer vibration isolation system structure is applied to the legs of a Stewart platform with Stewart platform with double-layer vibration isolation legs designed.The dynamic model of the vibration isolation platform is established based on the Kane equation,and the influence of the structural parameters of the legs on the dynamic response of the platform is analyzed.Moreover,the vibration isolation performance of the platform is analyzed through simulation calculation.This paper mainly carries out the following work:(1)The Structural design of Stewart platform with double-layer vibration isolation legs.In order to improve the vibration isolation performance of the Stewart platform,a double-layer vibration isolation system structure is introduced,and a double-layer vibration isolation leg for the Stewart platform is designed.According to the structural composition and movement characteristics of the Stewart vibration isolation platform,the overall structure design of the Stewart platform with double-layer vibration isolation legs is completed.(2)The establishment of dynamic model of Stewart platform with double-layer vibration isolation legs.The pose description matrix of the vibration isolation platform is obtained based on the coordinate transformation theory.In order to reflect the relationship between the force and movement of the components of the leg,a dynamic model of the leg established.The kinematics and dynamics relationship between the platform and the legs are analyzed,and the partial velocity and angular velocity of each component are constructed.The dynamic modeling of Stewart platform with double-layer vibration isolation legs is established based on the Kane equation method.(3)The dynamic response analysis of Stewart platform with double-layer vibration isolation legs.The first six natural frequencies of the vibration isolation platform without considering damping are obtained by formula method.Based on MATLAB numerical calculation,the acceleration response curve of the platform under different outrigger structure parameters(including the intermediate mass,stiffness and damping of the leg)is obtained.By analyzing the change law of the response curve,the intermediate mass,stiffness and damping of the leg are selected.(4)The vibration isolation performance analysis of Stewart platform with double-layer vibration isolation legs.The virtual prototype model of the vibration isolation platform is established based on ADAMS.The acceleration response of the upper and lower platforms is obtained through an excitation test with a frequency of 50 Hz on the model.And compared with the theoretical results to verify the correctness of the theoretical model.In order to analyze the vibration isolation performance of the vibration isolation platform,a frequency sweeping excitation test in the frequency range of 1-100 Hz is designed.The vibration level drop in six directions of the upper and lower platforms is obtained,and compared with the Stewart vibration isolation platform of general structure.The Stewart platform with double-layer vibration isolation legs designed in this paper has a vibration attenuation of 34 d B along the z-axis,which is significantly better than other passive vibration isolation platforms,It is verified that the Stewart platform with double-layer vibration isolation legs has better vibration isolation performance.