Angle Detection Methods for a CMOS Smart Rotary Encoder
Kazuhiro Nakano*, Toru Takahashi***, and Shoji Kawahito**
*Graduate School of Electronic Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011, Japan
**Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011, Japan
***R&D Center, NTN Corporation, 1578 Higashi-Kaizuka, Iwata, Shizuoka 438-8510, Japan
A CMOS smart magnetic rotary encoder is useful for compact equipment such as personal robots. In the proposed encoder, the geometrical angle of a magnet is detected with digital signal processing. The output signal of our proposed system is susceptible to sensor offsets caused by sensors mismatch and misalignment between sensor chip and magnet. The accuracy of angle detection method and the robustness to rotation axis misalignment depend greatly on the angle detection algorithm. This paper presents three types of angle detection and their performance in precision and compares rotation angle misalignment tolerance. Simulation results show that detecting two zero-crossing points in the signal profile, ZC method, is the most adequate for this system.
-  A. Häberli et al., “Two-Dimensional Magnetic Microsensor with On-Chip Signal Processing for Contactless Angle Measurement,” IEEE Journal of Solid-State Circuits, Vol.31, No.12, pp. 1902-1907, 1996.
-  K. Nakano, T. Takahashi, and S. Kawahito, “A CMOS Smart Rotary Encoder Using Magnetic Sensor Arrays,” IEEE SENSORS 2003, pp. 206-209, 2003.
-  J. Lau, P. K. Ko, and P. C. H. Chan, “Modelling of split-drain magnetic field-effect transistor (MAGFET),” Sensors and Actuators A49, pp. 155-162, 1995.
-  S. Kawahito et al., “An Integrated MOS Magnetic Sensor with Chopper-Stabilized Amplifier,” Sensors and Materials, Vol.8, pp. 001-012, 1996.
-  A. Nathan, A. M. J. Huiser, and H. P. Baltes, “Two-Dimensional Numerical Modeling of Magnetic-Field Sensors in CMOS Technology,” IEEE Transactions on Electron Devices, Vol.ED-32, No.7, pp. 1212-1219, 1985.
-  H. P. Baltes, and R. S. Popović, “Integrated Semiconductor Magnetic Field Sensors,” Proceedings of The IEEE, Vol.74, No.8, pp. 1107-1132, 1986.
-  J. J. Clark, “Split-drain MOSFET Magnetic Sensor Arrays,” Sensors and Actuators A, Vol.24, pp. 107-116, 1990.
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