Smart Data-Driven Optimization of Powered Prosthetic Ankles Using Surface Electromyography

• Published in: Sensors (Basel, Switzerland) Switzerland), 2018-08, Vol.18 (8), p.2705
• Main Authors: Atri, Roozbeh, Marquez, J Sebastian, Leung, Connie, Siddiquee, Masudur R, Murphy, Douglas P, Gorgey, Ashraf S, Lovegreen, William T, Fei, Ding-Yu, Bai, Ou
• Format: Article
• Language: English
• Subjects: Algorithms; Amputees - rehabilitation; Ankle; Artificial Limbs; Biomechanical Phenomena; Calibration; data-driven optimization; Electromyography; Gait; Genetic algorithms; Humans; Hypercubes; Latin Hypercube Sampling; Muscles; Nelder–Mead; parameter tuning; powered prosthetic ankle; Prostheses; Stiffness
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s18082705

The advent of powered prosthetic ankles provided more balance and optimal energy expenditure to lower amputee gait. However, these types of systems require an extensive setup where the parameters of the ankle, such as the amount of positive power and the stiffness of the ankle, need to be setup. Currently, calibrations are performed by experts, who base the inputs on subjective observations and experience. In this study, a novel evidence-based tuning method was presented using multi-channel electromyogram data from the residual limb, and a model for muscle activity was built. Tuning using this model requires an exhaustive search over all the possible combinations of parameters, leading to computationally inefficient system. Various data-driven optimization methods were investigated and a modified Nelder⁻Mead algorithm using a Latin Hypercube Sampling method was introduced to tune the powered prosthetic. The results of the modified Nelder⁻Mead optimization were compared to the Exhaustive search, Genetic Algorithm, and conventional Nelder⁻Mead method, and the results showed the feasibility of using the presented method, to objectively calibrate the parameters in a time-efficient way using biological evidence.