Analysis And Optimization Of Vibartion Isolation Stewart Platform For The On-board Precision Instrument

During the driving process,vehicles are affected by multi-freedom of vibration from such as road roughness and vehicle motor engine and so on.These vibration formed a wide-band,six-degree-of-freedom excitation on on-board precision instruments.Some medical microscopes such as medical or optical equipment?military weapons or equipment need to be maintained stable in order to operation well.In order to solve the vibration problem on the operation of these precision instruments,the structure of the six-DOF parallel platform Gough-Stewart platform was used as the design of the vibration damping platform to achieve six-degree-of-freedom excitation vibration isolation.Fistly,the paper made a theoretical analysis of the kinematic theory for this six-degree-of-freedom parallel mechanism.The theory of space coordinate transformation was briefly introduced and the space coordinates of this mechanism was modeled by using the principle of rotating coordinate transformation.Then the research on the difficulties of the parallel mechanism in the study of kinematics,that is,the kinematics solution,especially the forward kinematics solution,was studied in detail.The forward kinematic solution of parallel mechanism is based on multiple highly nonlinear formulas that can not be solved by common numerical calculation methods.To solve this difficulties during research,this paper proposed a new method that combines multi-objective genetic algorithm with least squares principle.An example was implement to verify the accuracy and practicability of the algorithm.According to the calculation result,the algorithm designed for forward kinematics solution in this paper is fast and of highly accuracy.The LMS error can be reduced as 0.009.It is an effective and feasible solution method.At the same time,this paper also introduced some basic research schemes such as the singular position and posture of the kinematics research and the mechanical influence factors of the maximum working space.Then the Gossilin method is used for solving the working space of the example Stewart platform.Then the paper did research on methods of dynamic solution to the 6-DOF parallel mechanism.Newton Euler's method has always been a common method for solving parallel mechanisms.However,this method is of redundancy and complexity and difficult to apply to actual algorithm design.This paper proposes to solve to the dynamic equation of a Stewart platform with the principle of virtual.This method is of good logical and easy to program.Also an example was designed to verify the feasibility of this solution.At the same time,according to the particularity of the parallel mechanism designed in this paper,that is,for the design of vibration isolation platform,this paper also used the Lagrangian formula to establish the spring-damping dynamic model.Also,this paper designed the virtual prototyping model of this vibration isolation platform by Solidworks and ADAMS.To ensure the accuracy and reliability of the model,the kinematics and dynamics simulation experiment of the virtual prototyping was implement repeatedly.For designing the semi-active vibration isolation system,this paper focused on spring-damping parameter design and optimization.The Latin hypercube sampling combined with analytic hierarchy process was used on comprehensive optimization design of multi-objective parameters.The quantitative analysis of the final simulation results can be concluded that the design parameter for the virtual prototype of the vibration isolation in the direction of the six degrees of freedom is: [92.53%,87.47%,94.70%,87.61%,89.63%,61.2% ].This paper addresses the difficulties in the research of the six-DOF parallel mechanism,and puts forward its own innovative solution to the theory of forward kinematic solution and dynamic solution.At the same time,an accurate and reliable virtual prototype model is established.The simulation results have an intuitive and accurate reference value for the design of the physical prototype,which can greatly save the cost and experiment time in the physical prototype design process.A parameter optimization method was proposed for the vibration isolation platform to promote vibration isolation performance.The design of this vibration isolation platform improved the working conditions of on-board precision instruments.