The Design And Study Of Open CNC System Of Two-Dof Parallel Manipulator

Parallel machine tool is the outcome of parallel architecture and NC machine tool. Compared with traditional machine tool, parallel machine tool has such advantages as better stiffness, high load carrying capacity, precise positioning capability and high respond velocity, so it has greatly wide application foreground. Since parallel machine tool come out in the 1990s, the researchers have proposed diversiform parallel architectures and done a lot of useful work of multi-degree-of-freedom parallel architecture. But multi-degree-of-freedom parallel architecture has such disadvantages as difficult modeling, kinematics coupling, furthermore a lot of customers needn't six-degree-of-freedom machine tool. Therefore some less-degree-of-freedom parallel architecture which has advantages as simple mechanism and lower cost has been a new study field and has obvious market potential.Because several degrees of freedom of parallel mechanism is nonlinear and coupled, the tradition NC principle can't be applied in parallel machine tool directly. And it is difficult for existing NC software to offer parallel machine tool input information. Thus it makes the study of NC system difficult and effects application of the parallel machine tool. This dissertation presents a new two-DOF parallel manipulator and studies the key application issues of CNC system of this manipulator.According to characteristic of parallel mechanism the mathematical model of the two-DOF parallel manipulator has been set up. And the direct position kinematics, the inverse position kinematics, the direct velocity kinematics and the Jacobian are given, and the workspace is analyzed. Furthermore the parallel prototype has been manufactured. According to characteristic of parallel mechanism and the different control rule between traditional NC machine and parallel NC machine , the CNC system with open modular architecture has been set up. Because the software module and hardware module have been designed based on standardization and diversification, the deviser can set up system with different module such as building block.This dissertation adopt the framework of multi-PC and set up the hardware system with PC and standard control card. And this framework can greatly simplify the structure of the control system and has good reliability and opening ability. In the developing process of software system, The NC code is adopted as input code of parallel manipulator in order to maintenance compatibility with the traditional CNC system. The CNC system is designed by the method ofobject-oriented and modularization, and the interface is programmed with Visual C++ in operating system of windows 2000. In order to control parallel manipulator directly dynamic link library technology is applied. At last the practical control experiment has been done, and the reasonable expected result is gained. So the CNC system is proved to be correct.