如今中風逐漸有年輕化的趨勢，慢性病（高血壓、高血糖及高血脂）的盛行更是提升了罹患中風的機率。大多數的中風後倖存者需要長期的復健來恢復其維持日常生活的能力，而基於約有88%的患者在中風後即表現出一定程度的偏癱步態，復健的成效與康復的情況可以藉由雙腳間的各種步態特徵的對稱性來加以評估。然而大多數的步態分析系統只有在生物力學實驗室或相關醫療機構才會提供，且其價格昂貴、所需空間大而費時的特點已經被證實並不適用於臨床應用上，更別提居家使用。因此，開發一套簡易的穿戴式復健評估裝置已經成為一項臨床上的重要議題。
本研究將兩個慣性測量單元分別固定於雙腳的外側，步態模式以加速度與角速度的形式被擷取。基於加速度計與陀螺儀本身的限制，本研究透過常用於無人機上的感測器融合技術來令兩個元件相互校正，再整合研究中開發的演算法以盡可能估測出正確的步態特徵。考量到患者獲取資料以及審視評估結果的便利性，本研究於Android平台上進行系統的開發，為了兼顧良好的使用者經驗，不只顧及到功能的完善與操作的流程，使用者介面的精細設計也是必須的。慣性測量單元所測量的原始資料會藉由藍牙4.0的技術，以無線傳輸來將資料傳遞給智慧型手機或平板電腦，經過一連串的計算後，患者將可以在手機應用程式上看到雙腳間的對稱性評估。藉由觀察每一次復健完畢的對稱性評估，將可以獲悉康復程度的多寡。
本研究設計了兩套實驗來進行系統的測試：在實驗一，受測者會採固定距離的直線步行，該距離分別有0.6公尺、0.9公尺與1.2公尺，藉由實際行走的已知距離和系統推測出的行走距離之間的落差來評估系統的可靠性；在實驗二，受測者會被要求分別在沒有配戴負重以及有配戴負重的情形下，採自行選擇或舒適自然的速度進行直線步行，以單腳負重所進行的異常步態模擬將被用來評估系統對於健康與異常的分辨能力。本研究結果顯示，在實驗一中的步幅估測與理論值之間的落差並不大，但隨時間而產生的誤差累積會讓總距離誤差變嚴重。實驗二中，對於沒有任何異常下行走的受測者，在各種步態特徵中都有著大約1的對稱比例，那意味著雙腳間在各種步態特徵中都有著很好的對稱性。而對於左腳產生步行困難的受測者而言，其對稱比例都是大於或小於1，代表著左腳或右腳在某些步態特徵中會明顯大過於另外一隻腳。簡言之，雙腳間的各種步態特徵都會出現不一致的情況，也與實驗進行前的假設一致。

Nowadays, there is a trend of persons who suffer from cerebrovascular accident at a younger age. The prevalence of chronic diseases (hypertension, hyperglycemia and hyperlipidemia) even raise probability of stroke. Most of the survivors after stroke require a long term rehabilitation to improve and recover their ability of daily living. The rehabilitation effect and recovery situation can be assessed by a variety of gait characteristics between both feet based on the proportion that about 88% of post-stroke patients have certain degrees of hemiparesis. However, many gait analysis system is only provided in biomechanical laboratory or related medical institute. Besides, the elaborate systems have been verified that they aren’t suitable for clinical applications based on some characteristics such as expensive, requirement of large space and time-consuming, let alone using at home. Therefore, how to develop a simple wearable device for evaluation of rehabilitation outcome becomes a needful clinical issue.
In this study, two inertial measurement units were placed on lateral side of both feet respectively. The gait pattern was extracted in the form of acceleration and angular velocity. On the basis of the limitations of accelerometer and gyroscope, this study applied sensor fusion technique which is usually used in unmanned aircraft system to make two elements calibrate each other. Then these data were integrated with the algorithm which was developed in this study to estimate correct gait characteristics. Considering the convenience of receiving data and observing result for patient, the system was developed in Android platform. In order to satisfy the user experience, it is necessary to improve not only consummation of function and procedure of operation but also well-design of user interface. The raw data which were measured by inertial measurement units would be transmitted to smartphone or tablet via Bluetooth 4.0 which is a wireless technique. Patients could observe their own asymmetry assessment between both feet on mobile application after a series of calculations. Recovery situation could be learned by the observation of symmetry ratio after each rehabilitation.
Two experiments were designed in this study in order to evaluate the system effect. Experiment 1 took place during the subject was walking in fixed stride length, the reliability of system would be evaluated in the experiment by the difference between actual and calculated stride length. There were three different fixed stride length: 0.6 m, 0.9 m and 1.2 m. Experiment 2 was aimed to preliminarily assess recognition ability for normal lower limb and abnormal lower limb. The subject was asked to walk straight in comfortable or self-selected walking speed. In order to simulate walking difficulty to subject, two 1.5 kg lead block leggings were attached to left foot. The result shows that the difference was not significant for each stride length in experiment 1, but the error would be serious with time due to error accumulation. For experiment 2, the symmetry ratio was about 1 in all of gait characteristics when the lead block leggings weren’t attached to left foot. That is, the good symmetry existed in a variety of gait characteristics for healthy people. On the other hand, the symmetry ratio was greater or smaller than 1 when the left foot was walking difficulty. It meant the left foot or right foot was stronger than another foot on some gait characteristic. In brief, there was inconsistency in various gait characteristics between both feet. The result was consistent with the presumption.

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