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Journal of Sensors
Volume 2015 (2015), Article ID 503852, 10 pages
Research Article

A Method for Measurement of Absolute Angular Position and Application in a Novel Electromagnetic Encoder System

1School of Software Engineering, East China Normal University and School of Mechatronics Engineering, Harbin Institute of Technology, Heilongjiang 150001, China
2School of Mechanical Engineering, Shanghai University of Engineering Science and Shenzhen Graduate School, Harbin Institute of Technology, Heilongjiang 150001, China
3State Key Laboratory of Robotics and System, Harbin Institute of Technology (HIT), JQR Building, High Technology Park of HIT, Yikuang Street, Nangang District, Harbin, Heilongjiang 150001, China

Received 14 July 2014; Accepted 4 April 2015

Academic Editor: Aldo Minardo

Copyright © 2015 Zijian Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


For the encoders, especially the sine-cosine magnetic ones, a new method to measure absolute angular position is proposed in the paper. In the method, the code disc of the encoder has only two circle tracks and each one was divided into and () equal code cells. The cell angles, changing from 0° to 360° between any two neighboring code cells, are defined to represent any position on the code disc. The position value of the same point can be represented by different cell angle values of different tracks and the absolute angular position of the point can be obtained by the difference value between the cell angle value of the outer track and the inner one. To validate the correctness of the method theoretically, the derivation process of the method was provided. An electromagnetic encoder system was designed and the experimental platform was established to test the method. The experimental results indicate that the electromagnetic encoder can measure the absolute angular position. Besides, it shows that the method is easy to be realized in algorithm and can reduce computational complexity and decrease dimension of the encoder.