A Simplified Linearizer for TMR Angle Sensor-Design and Performance Verification

Abstract

In this paper, a simplified linearizer for Tunneling Magneto-Resistance (TMR) angle sensor (SLTA) is presented. The TMR angle sensor gives sine and cosine natured output voltages with-respect-to the angle of rotation of the shaft, and therefore, is said to be non-linear in nature. The proposed SLTA processes these two signals using an efficient technique and renders a linear direct-digital output for 360° range. The SLTA employs less number of low-cost electronic components. The working methodology of the SLTA is mathematically explained in detail. The performance of SLTA is verified first using simulation and emulation studies. The SLTA output is found to vary linearly for full-circle range. The worst-case non-linearity obtained in simulation and emulation study is 0.012% and 0.039 %, respectively. Results obtained in emulation-based additional tests confirm the applicability of the SLTA for dynamic input measurement. A shaft angle sensing unit, which employs a TMR angle sensor, is fabricated for the actual experimentation purpose. The SLTA is then interfaced with the unit, and tests are conducted. In experimentation also, the SLTA output is found to vary linearly for full-circle range. The maximum non-linearity observed in experimentation is 0.3 %. The proposed SLTA can find applications in various fields such as automobile, aerospace, medicine, robotics, etc.