Design Method And Experimental Research Of Reconfigurable Parallel Mechanisms Based On Five-Bar Mechanism

The innovation of mechanical equipment depends on the novelty of the mechanism structure.Nowadays,product and manufacturing process customization demand is getting higher and higher.Reconfigurable parallel mechanism has the characteristics of reconfigurable structure and flexible motion,which can respond to the requirements of modern mechanical products and manufacturing process customization.It can adapt to different working environment and flexible requirements for different tasks.It has become a research hotspot in the field of robotics and robotics.The planar parallel mechanism(PPM)has the merits of simple configuration,easy control,low cost and wide application.Two degree-of-freedom(DOF)five-bar PPM is a typical representative of PPM,and it can realize arbitrary trajectory motion in the plane.But there is a lack of a perfect reconfigurable design method.Therefore,the reconfigurable design method of PPM based on five bar mechanism is studied in this paper.The five sections of this dissertation are organized as follows:(1)Based on variable-topology design for mechanism structure,modular design and Lie group theory,a novel structural design method for reconfigurable parallel mechanisms is proposed.A class of mechanism configurations is the master model for structural design.Taking into account the relationship between structural scale constraints and motion constraints,the new kinematic limbs are constructed.Series of novel configuration families with topology association are generated through various configuration changes,including variable actuated layout,variable parameters,and variable kinematic limbs.Parameter-driving design with all-data association is carried out,providing a theoretical basis for structural design of reconfigurable mechanisms.Variable actuated layout may lead to less singular configurations,larger workspace and higher mechanism stiffness.(2)The main configuration model with full-information of bars and pairs are established.Series derived structures are designed for reconfigurable PPM,and kinematic characteristics of different kinematic patterns are analyzed.Thirteen basic configurations of the five bar mechanism are established based on 5R mechanism,and 5R metamorphic closed-loop limbs are derived.Kinematic characteristic of 5R,3R2 P,2R3P metamorphic configuration and their hybrid kinematic chains are described through Lie group.Taking 3-RRR mechanisms as the main configuration,seven configurations and their novel derived configurations are invented.Eight novel configurations with different motion patterns are derived on the 3-RRR+P hybrid platform.Novel planar lower-mobility parallel mechanisms with coaxial revolute joints on fixed base are designed.The novel mechanisms have larger workspace.These provide reference for design and optimization of configuration.(3)In this paper,the kinematic analysis of reconfigurable PPM is presented,and the CAD geometric analysis method is proposed to search mechanism reachable workspace.The three kinematic analytical methods of 5R mechanism are analyzed and compared.Based on the geometric method,the motion locus and motion characteristics of 5R mechanism and 5R mechanism with variable actuated layout are studied.Meanwhile,Experimental verification of kinematic controllability is attained.The unified kinematic equations of 3-OOF PPM are established.The kinematic characteristics of derivative 5R mechanism are researched.The CAD geometric analysis method is used to attain reachable workspace and simplify the numerical calculation process.(4)Based on the three dimensional CAD platform SolidWorks,the CAD rapid design system of 2-DOF and 3-DOF PPM is developed.Configuration design,dimension synthesis and kinematics analysis are integrated into the system.The system contains thirteen configurations of five bar mechanism and eight configurations of 3DOF PPM.It is helpful for the designers to accomplish the structural design,dimensional synthesis and kinematic analysis of 2-DOF and 3-DOF PPM.(5)An experimental platform of five bar mechanisms is set up with the DMCNET(Delta Motion Control Network).Experimental study on the kinematic characteristics of 5R mechanism and its application in Engineering are developed.The experimental results verify the correctness of the control method based on the forward and inverse solution of motion trajectory.The output trajectory is controllable and stable.Considering the packaging requirements of different sizes of customized cartons,reconfigurable carton packaging machine and egg tart packing machine are developed,which are made up of variable actuated layout five bar mechanisms.The folding processes for different sizes of the cartons are accomplished.It will be helpful for the delivery staff to improve the working efficiency and reduce the workload.The dissertation was supported by the National Natural Science Foundation of China(Grant No.51275486).Based on the above design method and experimental study,the design method of new configuration is derived.The development of computer aided design and motion analysis system for reconfigurable parallel mechanism is helpful to improve the design efficiency.The application of packaging and experimental research provides reference for the design and engineering application of new configuration.The research of this paper can improve the design theory of reconfigurable parallel mechanism,and quickly respond to the requirements of product and manufacturing process customization.