Control Reference Parameter for Stance Assistance Using a Passive Controlled Ankle Foot Orthosis—A Preliminary Study

• Published in: Applied sciences Vol. 9; no. 20; p. 4416
• Main Authors: Adiputra, Dimas, Abdul Rahman, Mohd Azizi, Ubaidillah, Mazlan, Saiful Amri, Nazmi, Nurhazimah, Shabdin, Muhammad Kashfi, Kobayashi, Jun, Mohammed Ariff, Mohd Hatta
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.10.2019
• Subjects: Angular velocity; Ankle; ankle angular velocity; ankle torque; Body mass; Body mass index; Body size; Brakes; control parameter reference; Data collection; Electromyography; Experiments; Feet; Fitness equipment; Foot drop; Gait; Locking; magnetorheological brake; Mechanical properties; Orthoses; Parameter estimation; Regression analysis; Rehabilitation; Sensors; Spasticity; stance assistance; Standard error; Velocity; Walking; walking speed; Malaysia
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app9204416

This paper aims to present a preliminary study of control reference parameters for stance assistance among different subjects and walking speeds using a passive-controlled ankle foot orthosis. Four young male able-bodied subjects with varying body mass indexes (23.842 ± 4.827) walked in three walking speeds of 1, 3, and 5 km/h. Two control references, average ankle torque (aMa), and ankle angular velocity (aω), which can be implemented using a magnetorheological brake, were measured. Regression analysis was conducted to identify suitable control references in the three different phases of the stance. The results showed that aω has greater correlation (p) with body mass index and walking speed compared to aMa in the whole stance phase (p1(aω) = 0.666 > p1(aMa) = 0.560, p2(aω) = 0.837 > p2(aMa) = 0.277, and p3(aω) = 0.839 > p3(aMa) = 0.369). The estimation standard error (Se) of the aMa was found to be generally higher than of aω (Se1(aMa) = 2.251 > Se1(aω) = 0.786, Se2(aMa) = 1.236 > Se2(aω) = 0.231, Se3(aMa) = 0.696 < Se3(aω) = 0.755). Future studies should perform aω estimation based on body mass index and walking speed, as suggested by the higher correlation and lower standard error as compared to aMa. The number of subjects and walking speed scenarios should also be increased to reduce the standard error of control reference parameters estimation.