Kinematic Analysis And Optimization Of Joint-Drive Type 3-DOF Parallel Manipulator

Mankind's pursuit the automation equipment through hundreds of years, has impelled emergence and development of the robot. Since 1961 the United States invented the first industrial robot, the robot has been developed rapidly. It is widely used in various industrial sectors, such as services, health care, entertainment and many other areas. It impact on the live of mankind. Referring to the more modern industrial robot, robots are composed of the base, waist (shoulder), big arm, arm wrist and hands. Big arm and arm form connect tandem, thus, also known as serial robot. Most of the current researches focus on robotics in this area, when the vigorous development of robots in the series, there was a completely new category of robots--parallel robots. It is a strong complement to expand the whole scope of the application of robots. Many scientists are very concerned with it. It becomes one of hot issues.This paper studies the joint-drive type three-degree-of-freedom parallel manipulator. To begin with, introduce the present situation of the three-degree-of-freedom parallel manipulator, research and analysis methods, study results that have been made by domestic and foreign scholars, structure analysis and overall design using parallel mechanism theory. Secondly, kinematics analysis of this mechanism, including direct position analysis, inverse position analysis, velocity and acceleration analysis, obtain the closed-form velocity and acceleration formula, this provide a theoretical basis for the developing control system and further study of the mechanism Finally, build mathematical optimization model based on kinematics analysis, then optimized design of basic parameters and driven unit by complex method.In this paper, following aspects are presented:First Structure analysis and overall design. First introduce basic theory of spatial parallel mechanisms, the concept of basic elements in brief. Secondly describe its background and development. Finally,structure analysis and overalldesign based on parallel mechanism theory, calculation of freedom.Second Kinematics analysis: Parallel robot kinematics can be divided into two sub-problems: forward kinematics and inverse kinematics. When given the importation of parallel robot joint position and parameters in the configuration to solve location and pose of the platform, it is forward kinematics. When given location and pose of the platform to solve importation of parallel robot joint position and parameters in the configuration, it is inverse kinematics. For parallel robot, its inverse kinematics is very simple. But its foward kinematics is very complex. To parallel robot, forward kinematics has been one of the difficulties. In this paper, use vector to complete the kinematics analysis according to characteristics of the mechanism, including direct position analysis, inverse position analysis, velocity and acceleration analysis, obtain the closed-form velocity and acceleration formula, this provide a theoretical basis for the developing control system and further study of the mechanism.Third Optimization of the basic parameter and driven unit. According to optimization theory and the features of this mechanism, build mathematical model of basic parameters and driven unit. The mathematical model contains a number of variables and constraints, it is inequality constraint optimization problem. To solve the problems of this type, we can use direction of search optimization, complex method and penalty function. Upon analysis, complex method is the best way to solve this problem. Complex method is an important direct method to solve constrained optimization problems. Its basic principle is to generate the initial complex in feasible field constructed by k vertices. Compare function value of initial complex,then find out the worst point whose function value is the biggest. According to the principle, find out the point that makes the objective function monotonically decreasing and replace it, constitute a new complex. Every change in the shape of a complex, move close to the optimal point until converge to the optimal point. Complex method needn't the differential coefficient of objective function, its process is simple.Forth According to the complex method, programme using Visual C + + 6.0. The man-machine interface procedures used visual programming, user can accessto the information needed to optimize, they also can choose specific optimal parameters, according to their; This optimization software system opens the optimization variables and constraints for users, they can chose freely. This increases the flexibility of the software. According to reasonable choice constraints, the procedures can give optimal result. Finally, we may see the optimization of the performance increase deeply compared with the original.Due to the different design requirements of parallel robot, this research is only a small aspect, we will study further in the future, our goal is to manufacture a parallel robot with higher level of automation and lower costs in the future. In this paper only used complex method to optimize, more advanced modern and new optimization methods are to be discovered.