Research On Compliant Assembly Technology Of Shaft-hole Based On Rigid Flexible Hybrid Generalized Parallel Mechanism

In the field of modern intelligent industrial robots,robot compliant assembly is an important research topic.The problem of shaft hole assembly belongs to the interaction between the robot and the unknown environment,so the focus of the research is mainly on the compliance issues,especially the problems of collision impact,compliant direction and position deviation adjustment when the shaft hole is in contact.The six DOF parallel manipulator has a wide application prospect in the field of assembly,especially in the field of large work pieces,because of its high precision and strong bearing capacity,so it makes special requests to the stiffness characteristics,coupling characteristics and control strategy of the parallel mechanism.This paper focuses on the compliance problem of the assembly of shaft holes,combining active and passive compliance,and develops mechanism design,control analysis,assembly simulation and experimental verification on the basis of rigid-flexible generalized parallel mechanism.Firstly,the paper analyzes the process of the shaft hole assembly,determines the difficulties existing in each stage,identifies the solutions to the related problems,and proposes a design scheme for the shaft hole assembly system with both the active and passive compliance characteristics,and selects the rigidflexible generalized parallel mechanism as the design mechanism.In this paper,the stiffness of the mechanism is analyzed,the stiffness matrix expression of the mechanism is derived,and the evaluation index of the stiffness coupling relationship is given through the definition and parameter drawing of the generalized parallel mechanism,which lays a theoretical foundation for the further mechanism design.Secondly,on the basis of the theoretical analysis,combined with the design requirements of the mechanism,the comprehensive design of the rigid-flexible generalized parallel mechanism is designed.The design will use the generalized parallel mechanism stiffness matrix as a calculation tool to analyze the stiffness,coupling,local isotropic and compliant orientation of different rigid-flexible hybrid configurations,and then a rigid-flexible generalized parallel mechanism design with passive compliance characteristics is finished.Then,through the collision stability analysis during the assembly contact phase,the stiffness design requirements of the mechanism are determined,and the active compliant control strategy of the assembly system is studied.The control system will adopt the control structure of the force ring to contain the position loop,and the shaft hole assembly simulation model will be established further.A variety of assembly boundary conditions are selected to perform a comprehensive simulation of the shaft hole assembly to verify the practicability of the active and passive compliant assembly systems.Finally,based on the theoretical analysis,an experimental prototype of a rigid-flexible generalized parallel mechanism is built,and the theoretical analysis and simulation are verified comprehensively through experiments.