Mechanical System Design and Analysis of Three Dimensional Scanning Probe Based on Flexible Parallel Mechanism

Mechanical coupling is one of the key factors that cause scanning probe mechanical error. Minimizing or eliminating the mechanical coupling error can Optimize structural design of the probe. A three-dimensional scanning probe is designed with three-brach flexibility parallel mechanism, whose guiding stiffness based on the energy method is derived. Mechanical coupling error is simulated and analyzed with finite element method in the paper. The result shows that three-branch parallel scanning probe reduces the mechanical coupling error to about 20% of the error of serial mechanism probe. Introduction With the rapid development of science and technology, coordinate measuring machine (CMM), a typical representative of modern measuring technology, has been widely used in industry. The probe is an important component of CMM and its development affects the performance of CMM. Only when the precise measuring probe provides the new measuring principle and the new measuring accuracy for CMM, can precision and efficiency of the CMM get further development ] 1 [ . Touch scanning probe, a kind of device which is often used in precise measurement, has many advantages such as high precision, good repeatability, no pre stroke error and so on. Some famous companies such as the United Kingdom Renishaw, Germany's Klingberg, Leitz and Zeiss Carl, Switzerland's Mecartex and the United States EMD and so on, have been in a leading position in studying the scanning probe. The measuring probe that German Mauser-WerkeOberndorf GmbH developed, whose guiding mechanism adopts three-layer reed, is a device with the typically serial structure ] 2 [ and has the advantages of simple structure. But moving parts of each measuring axis have different quality, which leads to the different dynamic characteristics of each directions. A parallel scanning probe, German FritzErtl Schweinfurt designs in patent U.S.Pat No.5029398 ] 3 [ , whose guiding mechanism is composed of parallel spring mechanism in flexible hinge mechanism, but it is difficult to manufacture and assemble for the mechanism. A compound serial-parallel probe ] 4 [ , Germany Klingelnberg designs in a patent, compensates measuring error with the two-dimensional hinge bar, but it is difficult to manufacture for its two-dimensional trapezoidal hinge bar. TRAX, a scanning probe system developed German Leitz ] 5 [ , avoids the cosine error and eliminates the mechanical zero error, which leads to the high accuracy. But it is difficult to promote practical use because the motion of each axis is realized by sliding friction. At present, the common scanning probe especially the traditional series probe has the mechanical coupling phenomenon in scanning measurement. It has larger mechanical coupling error and lower measuring precision. Therefore, it is the focus for our research to design a scanning probe with small coupling or even no coupling. Structure and Principle of Scanning Probe At present, the common scanning probe with serial-parallel form still exists mechanical coupling error. Therefore, it is the focus of designing a decoupled scanning probe based on the parallel principle, minimizing the mechanical coupling error. In this project, the parallel ] 9 6 [  guiding mechanism is composed of three identical integrated hinges. Displacement detection method adopts 6th International Conference on Mechatronics, Computer and Education Informationization (MCEI 2016) Copyright © 2016, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 130