Investigation Of 3-DOF Parallel Motion Simulation Platform With Overload And Redundant Actuation

Ships sailing on the sea will be disturbed by the marine environment and produce a variety of uncertain movement,which brings a serious threat to the safety of shipboard helicopter landing.Motion simulation platform in the laboratory or land environment can reconstruct multi-dimensional oscillating movement of the ship on the sea,providing a safe training environment for shipboard helicopter landing,which is of great strategic significance.Existing all-electric driven parallel mechanisms are difficult to achieve large and heavy requirements.To overcome these problems,the paper develops investigation of overload and redundant actuation mechanism with parallel structure.The main research contents are as follows:Firstly,according to the ship motion parameters,the design index of the simulation platform is developed.For existing parallel mechanisms are difficult to achieve large and heavy loading,a 3-DOF redundant actuation parallel mechanism with joint static load balancing device is presented,and analyzed its inverse position.Based on which,the reachable workspace is searched by the constraint condition of the mechanism.Secondly,the kinematic model of the mechanism is established based on the influence coefficient method,and the mapping relation between the generalized velocity,acceleration and active input is obtained.Through the evaluation of the Jacobian matrix of mechanism for distinguishing its singularity,the singularity is given.Combined with the virtual work principle,the flexibility model of the simplified mechanism of 3-(2-(?)R)S is established and on this basis,the direction stiffness model is established.Thirdly,by introducing Newton-Euler's equation of a rigid body using screw algebra,the dynamics Hessian matrix in joint space is gotten.Based on the dynamic Hessian matrix,the dynamics of 3-(2-(?)R)S simplified mechanism 3-PRS is analyzed.Using the D'Alembert's principle established the dynamics model of 3-(2-(?)R)S and gave the numerical exampples.Then,this paper studied(2-(?)U)S and(2-(?)S)S of two different structure of the movement branches,which provided a theoretical basis for practical engineering application.Established the dynamics model of branch including joint static load balancing device,and the counterweight is optimally designed by aiming at the branch driving force.Finally,designed the structure of prototype machine of ship motion simulation platform based on Solidworks software.Through the system simulation,the maximum index of each performance parameter under different motion condition is obtained,and the parts of the linear motion unit are selected.And the finite element analysis of the key components is carried out to ensure the rationality of the design.