患者自控式下肢癱瘓者步行輔具(UPGO)之速度控制

Abstract

因脊髓損傷造成的神經肌肉功能失常，使得下半身癱瘓者大多依靠輪椅來從事日常活動。下肢助行輔具能夠幫助患者起身行走，改善因長期仰賴輪椅帶來的問題，提升生活品質，給了癱瘓者一絲希望。由於被動式的下肢助行輔具，對於患者行走時相當大的負荷，過於耗能與非常緩慢的步行速度，使得學者們不得不尋求更有利的解決辦法。由於現今電控技術進步，下肢動力外骨骼改善了被動輔具之缺點，以外在動力來源，提供患者關節所需的動力，成為了更好的選擇方案。目前市場所見的下肢動力外骨骼，都以四顆或以上的馬達來提供關節動力，考量下肢動力外骨骼輔具的可負擔性，及連續使用時間，臺大醫工所及輔研中心團隊設計一款患者自控式的交替式動力步行輔具(UPGO)，僅使用髖關節馬達及按鈕控制邏輯，幫助患者達到起身及行走的目的。 本文中的設計延續第一版UPGO的理念，增加了按鈕指壓可改變跨步速度的功能。而本研究的目的在於驗證指壓變速控制的效能，探討其行走流暢性、操控性以及省電性能。透過行走實驗，八位成年常人受測者穿著UPGO，分別以定速控制模式與變速控制模式進行四項行走任務，記錄其完成時間、步數，與馬達轉速及電流加以分析。實驗結果顯示，使用變速控制模式在部分步態分期較貼近常人曲線，且在特定空間之下具有較好的操控性，但若其跨步時間較定速控制模式長，整體而言未必較省電。

Most persons with paraplegia attributed to spinal cord injury, rely on wheelchairs for their daily activities. Lower limb gait orthoses could help them walk to gain physiological benefits and enhance quality of life. However, passive lower limb orthoses have caused detrimental burden on persons with paraplegia. As a result of high energy cost and slow walking speed of these orthoses, an alternative solution has been inevitable. Because of advancements in electric and motor technology, it has been proved that powered lower limb exoskeletons could provide persons with paraplegia enough joint power when walking and improve disadvantages of passive lower limb orthoses. Most powered exoskeletons equip four or more motors to provide joint power currently. In consideration of affordability and lightweight of powered exoskeletons, National Taiwan University’s rehabilitation engineering laboratory in the department of biomedical engineering has developed a user-intent powered gait orthosis(UPGO), where only two hip motors were used and a wireless push-button control was imbedded in the crutches to help persons with paraplegia walking. In this thesis, a second edition of UPGO was studied by adding a pressure sensor in the imbedded push buttons to implement a variable speed control by which users were capable to change their instantaneous walking speed. The purpose of this research was to validate the effectiveness of variable speed control, and investigate whether it could bring more fluent gait, more maneuverability and less power consumption. In the experiment, eight normal subjects wore the UPGO to perform four tasks on both constant speed mode and variable speed mode respectively. Walking speed and cadence was measured through both a 7 m walking and mental loading tests. Hip angular speed was additionally measured through a 7 m walking test. Maneuverability was assessed through an obstacle course and a narrow space task by measuring course and task completion times and the number of obstacle collisions. The electric power consumption was obtained by the time integration of recorded current of the hip motor and calculated operating voltage. The results showed that it appeared that the variable speed mode offered a closer to normal walking in partial gait cycle than its counterpart. In obstacle avoidance and narrow space task, the use of variable speed mode demonstrated lesser contact error. However, it did not reach conclusion that the variable speed operation consumed lesser power because the power consumption depends on the length of stepping time.