EMG Analysis of Lower Limb Muscles in Vertical Ladder Climbing for Active Knee-Based Exoskeleton Power Control

Document Type

Conference Proceeding

Publication Date

1-1-2025

Abstract

Active exoskeletons-wearable devices powered by motors-are being increasingly adopted in industrial settings such as manufacturing and construction, where they assist with physically demanding tasks by supporting joint movement and reducing muscular workload. One task that presents specific challenges for exoskeleton use is vertical ladder climbing, which is common in these environments for accessing elevated areas such as scaffolding, industrial tanks, or rooftops. As workers frequently shift between ground-level and elevated tasks, removing and re-donning a lower-limb exoskeleton for short transitions like ladder climbing is impractical. This study examined the ascent phase of vertical ladder climbing to evaluate right lower-limb muscle activation patterns (assuming bilateral symmetry) and implications for exoskeleton design. Eight participants provided electromyography (EMG) data from three muscles: Biceps Femoris Caput Longus (BFCL), Tibialis Anterior (TA), and Gastrocnemius Medialis (GM). The ascent phase was divided into stance and swing phases for a micro-level analysis of activation. EMG signals were processed with a 20-450 Hz band‐pass filter, and RMS values were computed and normalized by Maximum Voluntary Contraction (MVC). Statistical Parametric Mapping (SPM) was applied to assess differences in activation between muscle groups and to identify significant time points in the climbing cycle. Paired SPM t-tests comparing overall activation between muscle groups did not reveal significant differences (i.e., the SPM threshold was not exceeded). However, one-way SPM ANOVA analyses performed separately on each muscle indicated significant phase-specific differences-TA activation was different between 37% and 59% of the cycle (P = 0.014) and GM activation between 39% and 79% (P = 0.00013)-while BFCL activation remained consistent throughout the climbing cycle. These findings highlight the role of TA in mid-stance for foot stabilization, while GM contributes more to propulsion and control as the climb progresses.

Publication Source (Journal or Book title)

Iise Annual Conference and Expo 2025 Conference Proceedings

First Page

1333

Last Page

1338

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