| 摘要: | 不論是中風患者復健療程或下肢義肢穿戴者義肢矯正，皆由醫師或義肢矯具師主觀判定其康復狀況及步態，除仰賴經驗外，往後再回顧患者復健情形也不夠客觀，因此本研究開發一套量化評估人體下肢步態的系統；透過安裝7組無線慣性感測器於受試者下肢(包含腰部、左右大腿下外側、左右小腿下外側以及左右腳背處等)，擷取行走時的線加速度及角速度，分析受試者下肢行走軌跡及步態參數，包含(1)步態週期，(2)步速(Velocity)、步幅(Stride)及步頻(Cadence)，(3)骨盆冠狀面、矢狀面及水平面活動角度(4)髖、膝及踝關節屈曲角度等，如此可提供醫師或義肢矯具師量化結果，更加客觀地評估患者復健及矯正情形。
研究中，將訊號以Madgwick演算法，透過線加速度校正角速度偏差，並轉換為四元數，再計算尤拉角以避免奇異點及萬向鎖(Gimbal lock)的問題，根據腳背上IMU的線加速度資訊計算步態週期；以尤拉角分析骨盆三平面活動角度以及髖、膝及踝關節的屈曲角度，以運動學前解矩陣重建各關節活動軌跡使角度可視化，並透過零速更新法(Zero Velocity Update, ZUPT)描繪患者的步行軌跡，重建的受試者運動步態與步行軌跡可協助醫師或義肢裝具師判讀。
除用旋轉平台驗證單顆IMU的準確度外，也以商用機器手臂與光標系統分別驗證本系統之信度與效度，信度驗證中，二維運動軌跡的誤差百分比為0.7 – 0.9%，三維運動軌跡則介於1.65 – 1.78%；效度驗證中，髖、膝及踝關節活動角度的RMSE分別為
6° - 6.4°、6.16°- 6.74°及7.31° - 8.22°，其相關係數則為0.96、0.98及0.85。
末節收錄2位膝上與3位膝下義肢穿戴受試者的步態參數，分組分析其臨床意義。發現(1)不論是膝上或膝下義肢穿戴受試者，其行走重心會在健側停留較久，導致患側步態擺盪期較長。(2)步速、步頻及步幅與熟練度及身高有關，且身高越矮步頻越高。(3)膝上義肢穿戴受試者骨盆冠狀面與矢狀面的穩定性較差，旋轉角度範圍較大。骨盆三平面兩兩相關係數不論在膝上或膝下義肢穿戴受試者皆達0.9以上，屬高度正相關。(4)因代償作用導致膝上義肢穿戴受試者的患側髖關節活動角度範圍會略大於健側，膝關節活動角度亦是；而膝下義肢穿戴受試者患側髖關節活動角度範圍則略小於健側，患側膝關節活動角度大於健側。(5)不論是膝上或膝下義肢穿戴受試者的患側踝關節活動角度範圍會受義肢限制，略小於健側。
;The rehabilitation process for both stroke patients and lower extremity prosthesis wearers is subjectively determined by the physician or prosthetic orthotist, and in addition to relying on experience, it is not objective enough to review the patient′s rehabilitation later. Therefore, this study developed a system to quantitatively assess the gait of human lower limbs by installing 7 sets of wireless IMU on the lower limbs (including waist, lower and outer thighs, lower and outer calves, and left and right instep). The linear acceleration and angular velocity were captured to analyze the subject′s walking trajectory and gait parameters during walking, including(1)gait cycle (2)Velocity, Stride and Cadence (3)pelvic coronal, sagittal and horizontal rotation angles (4)hip, knee and ankle flexion angles, which can provide the physician or prosthetic orthotist with quantitative results to more objectively assess the patient′s rehabilitation status.
In this study, the Madgwick algorithm was used to correct the angular velocity deviation by linear acceleration and convert it to quaternion, and then the Euler angle was calculated to avoid the singularity and gimbal lock problems. The joint movement trajectory is reconstructed using a D-H parameters matrix to visualize the angles, and the patient′s walking trajectory is traced by Zero Velocity Update (ZUPT) to assist the physician or prosthetist in interpreting the subject′s posture and gait trajectory.
In this research, using rotation platform to verify the IMU accuracy, and the reliability and validity of the system were verified with a commercial robotic arm and an optical motion capture system, and the percentage error of the two-dimensional motion trajectory was 0.7 - 0.9%, while the three-dimensional motion trajectory was between 1.65 - 1.78%; the RMSE of the hip, knee and ankle movement angles were between 6° - 6.4°, between 6.16° – 6.74° and between 7.31° - 8.22°. The correlation coefficients were 0.96, 0.98 and 0.85, respectively.
The gait parameters of 2 above-knee and 3 below-knee prosthesis wearers were collected in the last section and analyzed in groups for their clinical significance. Realized that (1) Both above- and below-knee prosthesis wearers will keep their walking weight on the healthy side for a longer period of time, resulting in a longer gait swing on the affected side. (2) Velocity, cadence and stride are related to the degree of proficiency and height, and the shorter the height, the higher the stride frequency. (3) The stability of the coronal and sagittal planes of the pelvis was poorer and the range of rotation angle was larger in the above-knee prosthesis wearers. The correlation coefficients of the three pelvic planes reached 0.9 or more in both above- and below-knee prosthesis wearers, which is a high positive correlation. (4) The range of hip motion on the affected side was slightly greater than that on the healthy side due to compensatory effects, as was the range of knee motion on the affected side, while the range of hip motion on the affected side was slightly less than that on the healthy side and the range of knee motion on the affected side was greater than that on the healthy side in the below-knee prosthesis. (5) The range of motion of the affected ankle joint was slightly less than that of the healthy side for both above- and below-knee prosthesis wearers. |
