Study On A Tripod Parallel Universal Wrist

The parallel kinematics machine has lots of strongpoints, for example, high stiffness, high carrying capacity, nice dynamic character, quick moving, simple frame etc. It has attracted people all over the world and will be one of the developed directions of the robot and numerical control machine. While, there are some shortcomings, for example, its mathematic model is very complex and hard to realize real-time control, its work space is small comparing with its volume, the gemel has interspaces and low contact stiffness etc, all above make the research of parallel kinematics machine staying on the phase of lab, hardly actualizing industrialization. It is more meaningful to solve the choke points that baffle the development of parallel kinematics machine, break the applying issue in some given fields, and actualize industrialization.This paper introduces a tripod parallel universal wrist based on the metamorphic gimbal. While, its configuration shows that it can work in a large work space and the end-operator (output of the gimbal) can get its location and direction by driving the mobile platform with two parallel bars when it is rotating. Therefore, this machine can be applied as the wrist of robot or a part of number control machine. The aim of this research is to design a new type parallel kinematics machine for the parallel theory study and experiment research, solve the key issues that baffle the development of the parallel kinematics machine. In this way, we can find an available way to generalize the application of parallel kinematics machine, provide theory elements and key technology for industrialization of the parallel kinematics machine (parallel robot), and impulse the development of the manufacturing equipments technology.Firstly, based on large quantities of literatures from civil and overseas, the history, strongpoints, shortcomings and development etc of parallel kinematics machine were summarized. The significance of this thesis's study was illuminated.Secondly, the related theories of the machine were studied. The vector kinematics equation and the matrix of Jacobian were created; The relationship of velocity and acceleration between input and output, and the velocity and acceleration of parallel bars were analyzed in detail;In the analysis of statics, the statics solution was created by using the principle of virtual displacement, illuminating the relationship of outside forces, driving forces and its gravity; By using the Lagrange equation, the dynamic model was created for the first time; Based on the statics and theory of stiffness, the stiffness equation and the matrix of stiffness were created for the first time; The stiffness characteristic of the machine was got by analyzing the condition coefficient of the stiffness; The dynamic characteristic was got for the first time, by analyzing the matrix of weight; The weight characteristic was got for the first time, by analyzing the weight coefficient of the machine.Finally, the 3D entity model and kinematics simulation were established by using the software-UG; Based on MATLAB,the kinematics,dynamics,statics,stiffness,weight characteristic,dynamic characteristic were simulated; The blueprint of assembly and parts were drew, having a detail design for the structure of the machine.