Design And Research Of Multi-Dimensional Vibration Reduction System Based On Parallel Mechanism

With the development of modern industry,more and more vehicles and ships are used in the transportation of passengers,equipment and materials.While rough roads,changing speeds,yawing and turning and other factors will cause multi-dimensional vibration,which also hinders rapid,efficient and safe transportation.So it will have very important and practical significance in designing multi-dimensional vibration reduction system.Multi-dimensional vibration reduction,along with large amplitude and low frequency vibration reduction,is the difficulty in the development of such system.The paper takes vehicular stretcher as the application background,designs a multi-dimensional vibration reduction system based on a four-degree-of-freedom(two shifts and two rotation)parallel mechanism,which actively controls motions of the main mechanism under the stretcher and reversely compensates the multi-dimensional large amplitude and low frequency vibration motion suffered by patients during the transportation to achieve vibration reduction control.This paper first establishes the kinematics model of the systematic parallel main mechanism,then completes systematic size parameter design,calibration and compensation based on the kinematics model,finally it designs the active control method and tests on the prototype,the experimental results show that the system has good anti-vibration ability,and has strong adaptability to different environment.The main contents of this paper are as follows:(1)Systematic main mechanism and kinematics modeling.It introduces the design requirements and main parts of the systematic main mechanism,and solves the degree-of-freedom of the main mechanism,then respectively sets up the forward and inverse kinematics models,and calculates the speed Jacobi matrix of the system.(2)Size parameter design of main mechanism based on systematic kinematics model.It sets up parameterized models of the given workspace and scale space,takes the maximum swing angle of each branch as the kinematic performance evaluation index,and uses genetic algorithm to find the right size parameter in a given size space so as to make the system have better motion characteristics and occupy smaller space while also satisfies the given workspace.(3)Calibration and compensation of size parameters of main mechanism based on systematic kinematics model.Through establishing the influence relationship model between each major error source and terminal output based on kinematics model,it sets up the error transfer model to calibrate and compensate the size parameters of mechanism,and then corrects the kinematics model and thus improves the terminal output precision and verifies the validity of the model through experiment.(4)Systematic active control method.Through analyzing the control difficulty found in the multi-dimensional large amplitude and low frequency vibration system,it sets up the active control algorithm model based on combining reverse linear acceleration/angular velocity compensation and recovery compensation.Then according to the evaluation index of the system,it uses genetic algorithm to optimize the parameters of the control algorithm model,and verifies the validity and adaptability of the method by experiment on the prototype.