Research On Automatic Centring And Levelling Precision Platform

Automatic centring and levelling precision platform is the core component of the high-grade roundness measuring equipment. It is also the key technology to realize high efficiency and precision measurement for the CNC gear measuring machine, three coordinate measuring machine and so on. At present roundness measuring equipment made in British Taylor Hobson company is the most advanced foreign automatic centring and levelling precision platform. Automatic alignment function of the workpiece was realized by the platform. Automatic centring and levelling precision platform has not been developed in China.Based on researching and analyzing the Automatic centring and levelling algorithm, the principle of three support leveling algorithm is grasped. And based on this algorithm the four points support leveling algorithm is put forward. A theoretical basis is provided to the design of the control system through simulating and comparing the advantages and disadvantages of the two algorithms. Five guiding mechanism which are used to design the automatic centring and levelling precision platform are researched such as parallel spring, semi-circular arc flexible hinge, plane flexible hinge and so on. The stiffness equation of guide mechanism is deduced by using the bending moment in the material mechanics. The correctness of the theoretical equation is verified by using finite element analysis software to simulate and analyze it.Based on researching on the centring and levelling theory and guiding technology,the bilateral circular arc flexible hinge is designed to level the workpiece and unilateral circular arc flexible hinge is designed to center the workpiece for Automatic centring and levelling device. This device is drove by stepper motor and controlled by the single-chip microcomputer. The offset of the workpiece which is sent to computer by transducer is decomposed into all motor shafts through the levelling and centring algorithm by upper computer. The control information was sent to the single-chip microcomputer through RS232serial communication port. The stepper-linear motor motion was drove by the driver controlled by the single-chip microcomputer. Through this way the automatic centring and levelling function of precision platform was completed. The prototype of this device is trial-produced, and the correctness of the regulation theory and the feasibility of the structure of the automatic centring and levelling precision platform was verified by doing some experiments.