Design And Analysis Of The Horizontally Deployable And Foldable Mechanism

In recent years,space deployable mechanisms have been more and more widely used in aerospace and engineering construction,and the demand for space deployable mechanisms with high and foldable ratio,high precision and high flexibility is becoming more and more urgent.In this paper,through the observation and summary of the evolution of the scissor mechanism,a kind of spatial horizontally deployable and foldable mechanism with controllable lateral deployable is conceived by using the design idea of series-parallel modular mechanism,and its design analysis,theoretical research and application research are carried out.Firstly,a kind of folding mechanism with lateral offset is designed based on the scissor mechanism.By modifying the position of the middle hinge of the direct shear and changing the length relationship of the shear rod,a scissor mechanism with controllable lateral deployable is obtained,and its scale analysis is carried out.Based on the design idea of parallel mechanism,the unit of horizontally deployable and foldable mechanism is obtained,and the unit structure diagram of horizontally deployable and foldable mechanism is constructed.Two series schemes are proposed to realize modular series connection for subsequent mechanisms,and the corresponding three-dimensional model of horizontally deployable and foldable mechanism is established.Finally,in order to make the mechanism have better foldable performance,the unit foldable ratio of horizontally deployable and foldable mechanism is calculated.Secondly,the kinematics analysis of the horizontally deployable and foldable mechanism is carried out.The kinematics equations of the deployable scissors mechanism,the horizontally deployable and foldable mechanism unit and the four-section horizontally deployable and foldable mechanism are established by the closed-loop vector method,the rotation matrix method and the D-H method respectively.The forward and inverse solutions of the position,velocity and acceleration of each variable are solved,and the deployment motion of the horizontally deployable and foldable mechanism unit is programmed and simulated to verify the motion feasibility of the mechanism.The workspace of the horizontally deployable and foldable mechanism is solved by Monte Carlo method.Based on the velocity Jacobian matrix,the singularity and operability of the mechanism are analyzed,and the optimization scheme is proposed.After that,two dynamic modeling methods for the model in this paper are proposed.One is to establish the dynamic model of the offset folding mechanism unit by Lagrange mechanics method.Secondly,when discussing the whole mechanism composed of multiple units in series,the dynamic modeling method based on Newton Euler method is used to analyze the force of the folding motion of the simplified offset folding mechanism,and the interaction force relationship between the units is obtained.Finally,the simplified dynamic model of the whole offset folding mechanism is established.Finally,the dynamic characteristics of the unit and the whole mechanism of the single offset folding mechanism are analyzed by simulation,which lays a theoretical foundation for the application of the mechanism in future.And then,the reliability analysis of the horizontally deployable and foldable mechanism based on kinematics and its application field are studied.From the plane deployable scissors mechanism to the horizontally deployable and foldable unit to the four-section series one,the mean and variance of the error of the deployment position,velocity and acceleration considering the rod length error and the hinge clearance are calculated respectively.An example is selected,and the corresponding reliability change trend based on kinematics is obtained by the first-order secondorder matrix method.Finally,the application of the deployable mechanism designed in this paper is studied,including vehicle-mounted telescopic emergency arch bridge,UAV space manipulator,and the corresponding virtual prototype is designed.The lateral offset deployable mechanism proposed in this paper enriches the types of deployable mechanisms and provides an effective and feasible scheme for its theoretical analysis.