Research Of 6-DOF Micro-displacement Measurement System

To deal with the problem of lacking the methods of how to measure the multi-degrees of displacement in the manufacturing industry and solve the difficulties of installing the equipment, a method of using the permanent magnet to produce the information of magnetic field in the air space and utilizing the information to resolve the displacement has been proposed. First, using the data of finite element simulation to plot the magnetic-field distribution and analyzing the technical characteristic based on the foundation of building the mathematic model of permanent magnet. Then, with the help of successive solving algorithm, the six-degrees of freedom displacement has been resolved and testified the accuracy and viability of the measuring system. At last, a measuring system has been built on the existed 6-DOF motion platform which completed the functions of measuring the 6-DOF displacement. The measuring system built in this project can achieve the high-accuracy of 6-DOF displacement and has the advantage of small-structure and low-costs. The main work of this paper is as follows:To meet the demand of measuring the multi-DOF displacement, the suitable magnetic field source should be chosen at first. The cylinder magnet and rectangular magnet are much better to form the magnetic field distribution to help simplify the resolution algorithm because of their symmetry. Then the relationship between the information of magnetic field and the space coordinates has been built by using the electromagnetism. Thus, with the use of finite element simulation, the data has been compared with the mathematic model which shows that the magnetic field distribution produced by the permanent magnet is able to be resolved in the resolution algorithm.After the derivation of the magnetic model, a hall-sensor scheme which is used to detect the information of magnetic field has been proposed. Then the detection model that based on the magnetic field information has been calculated. The essence of realizing the 6-DOF displacement measuring system is to solve the non-linear equations which contain the displacement element. In this paper, a successive solving algorithm is being used to solve the current coordinate. The algorithm is based on the motion consistency given the high sampling frequency it can resolve the current coordinate by using the last moment’s displacement data. What’s more, the measuring program has been simulated under the circumstances of ideal and noise situation with the help of Matlab which proves the accuracy of the measuring method.Finally, an actual measuring system has been built based on the simulation which used the existed 6-DOF motion platform. In this paper, the hall-sensor detecting circuit and the algorithm solving software haven been completed. To testify the accuracy and proficiency of the measuring system, the experiment has been carried on which achieved the pre-set target and is consistent with the simulation result.