目前市售絕對位置線型編碼器的種類根據操作原理區分為光學與磁性編碼器，根據使用環境及性能比較，磁性編碼器在精度上低於光學編碼器，但擁有極佳的環境強健性，因工業應用之編碼器必須接觸粉塵與油汙，磁性編碼器於惡劣的使用環境，仍可以維持常規精度，這是光學編碼器無法提供的。
本論文之研究目標為設計及分析線型磁性編碼器之感應式磁阻型絕對位置線型感測尺，採用電磁場電腦輔助工程分析軟體建立包含感測線圈及尺身的電磁分析模型，藉由尺身上開槽之幾何形狀形成磁阻不同的現象，輔以M序列編碼原理進行尺槽開孔之編排，配合感應線圈與激磁線圈的讀頭尺寸設計，深入探討感應線圈寬度、槽孔重疊寬度以及氣隙變化等做更進一步的分析探討。於擷取套裝軟體模擬的輸出感應電壓數據後，再經套裝數學分析軟體進行後處理，深入探討參數設計靈敏度及設計值範圍，用以提高位置訊號的讀取精度。本論文實驗部分為採用設計完成之尺身幾何參數，以精密數值控制切削加工的方式製作雛型尺，並於無塵室中架設於高精度的實驗平台，進行重現性及量測精度之驗證，確認理論及實驗製作之可行性及製作精度，完成讀取精度在4微米雛型尺。

Based on the operational principle, linear absolute position sensors are classified into optical and magnetic encoders. Although magnetic encoders are inferior to the optical encoders in measurement accuracy, they exhibit high robustness in various environments. In industrial applications, the linear encoders must operate under dust and oil contaminated conditions whereas magnetic encoders do not deteriorate in accuracy.
The objectives of this thesis are to design and analyze linear absolute position sensors based on the principle in inductive reluctance theory. With the help of M-sequence codes, ANSYS® CAE analysis, and AM decoding scripts in Matlab®, a prototype magnetic linear scale can be practically made to serve as benchmark examples. Design parameters, such as coil width, slot overlap, and air-gap width, are assessed for sensitivity studies. Furthermore, transient EM simulations coupled with Matlab Simulink® are conducted for transient modulation and decoding studies. Finally, the prototype scale was measured and compared with the commercial scale to demonstrate the accuracy is within +/- 4 um.

[1] Bera, S. C., Sarkar, R., & Bhowmick, M. (2011), “Study of a modified differential inductance measurement circuit as position transducer of a power cylinder”, IEEE Trans. on Instrumentation and Measurement, 61(2), pp.530-538.
[2] Aschenbrenner, B., & Zagar, B. G. (2014), “Analysis and validation of a planar high-frequency contactless absolute inductive position sensor”, IEEE Trans. on Instrumentation and Measurement, 64(3), pp.768-775.
[3] “編碼器種類、原理與運動量測方法“, retrieve from September 14, 2018, NATIONAL INSTRUMENT, http://www.ni.com/tutorial/7109/zht/
[4] Fericean, S., & Droxler, R. (2007), “New non-contacting inductive analog proximity and inductive linear displacement sensors for industrial automation”, IEEE Sensors Journal, 7(11), pp.1538-1545.
[5] Trankler, H. R., & Obermeier, E. (1998), Sensortechnik-Handbuch fur Praxis und Wissenschaft.
[6] Pallas-Areny, R., & Webster, J. G. (2012). Sensors and signal conditioning. John Wiley & Sons.
[7] Norhisam, M., Norrimah, A., Wagiran, R., Sidek, R. M., Mariun, N., & Wakiwaka, H. (2008), “Consideration of theoretical equation for output voltage of linear displacement sensor using meander coil and pattern guide”, Sensors and Actuators A: Physical, 147(2), pp.470-473.
[8] George, B., Tan, Z., & Nihtianov, S. (2017), “Advances in capacitive, eddy current, and magnetic displacement sensors and corresponding interfaces”, IEEE Trans. on Industrial Electronics, 64(12), pp.9595-9607.
[9] Li, Y., Sheng, X., Lian, M., & Wang, Y. (2016), ”Influence of tilt angle on eddy current displacement measurement”, Nondestructive Testing and Evaluation, 31(4), pp.289-302.
[10] Theodoulidis, T. (2005), ”Analytical model for tilted coils in eddy-current nondestructive inspection”, IEEE Trans. on Magnetics, 41(9), pp.2447-2454.
[11] Vasiloiu, V. (2003). U.S. Patent No. 6,611,138. Washington, DC: U.S. Patent and Trademark Office.
[12] Matsumoto, T., & Ohno, K. (1996). U.S. Patent No. 5,563,408. Washington, DC: U.S. Patent and Trademark Office.
[13] Ohno, K., Hattori, T., & Matsumoto, T. (1991). U.S. Patent No. 5,068,529. Washington, DC: U.S. Patent and Trademark Office.
[14] Vasiloiu, V., & Eisschiel, H. (2015). U.S. Patent No. 9,013,192. Washington, DC: U.S. Patent and Trademark Office.
[15] 洪麒富(2018)。感應式磁阻型線性位置編碼器設計與分析，國立清華大學動力機械工程學系碩士學位論文，未出版，國立清華大學
[16] Nagase, T., & Higashi, K. (1992). U.S. Patent No. 5,117,105. Washington, DC: U.S. Patent and Trademark Office.
[17] David K. Cheng (2014). Field and Wave Electromagnetic, 2nd Ed. Pearson College Div, pp.332-339.
[18] “Absolute encoder based on the AMOSIN-Inductive Measuring Principle“, retrieve from October 30, 2018, AmoAutomatisierung, http://www.amogmbh.com/fileadmin/amo/pro-dukte/prospekt/Prospekt_ABSOLUTE.pdf