Semester of Graduation

Summer 2025

Degree

Master of Construction Science and Management (MCSM)

Department

Bert S. Turner Department of Construction Management

Document Type

Thesis

Abstract

Active exoskeletons are increasingly utilized in physically demanding industries such as construction and manufacturing to reduce strain and lower the risk of work-related musculoskeletal disorders, supporting worker safety and long-term health. However, most existing systems are designed for repetitive tasks like lifting or prolonged standing, with limited consideration for dynamic activities such as vertical ladder climbing. Ladder climbing is common and physically demanding in industrial environments, often required to access elevated areas like scaffolding, tanks, or rooftops. Since exoskeletons are intended to remain worn throughout multiple tasks, requiring workers to remove and re-don the device during ladder climbing would reduce usability. This study investigates lower-limb muscle activation during vertical ladder ascent to provide biomechanical insights that may inform adaptive exoskeleton control strategies. Assuming bilateral symmetry, EMG data from the right leg were collected for three muscles: Biceps Femoris Caput Longus (BFCL), Tibialis Anterior (TA), and Gastrocnemius Medialis (GM). Eight participants performed ascent trials, with the climbing cycle divided into stance and swing phases for micro-level analysis. EMG signals were band-pass filtered (20–450 Hz), rectified, and smoothed using RMS normalized to Maximum Voluntary Contraction (MVC). Statistical Parametric Mapping (SPM) identified phase-specific differences in activation: TA showed significant activation between 37%–59% of the cycle (P = 0.014), stabilizing the foot and preparing for toe-off. GM was active from 39%–79% (P = 0.00013), contributing to propulsion and balance. BFCL showed relatively stable activation, suggesting a consistent stabilizing role. A supplementary pilot study explored activation across eight lower-limb muscles during vertical and A-shaped ladder climbing, using walking as a normalization reference. Based on four participants, upper-leg muscles—Rectus Femoris, Vastus Medialis, Vastus Lateralis, and Semitendinosus—showed significantly higher activation during climbing. In contrast, lower-leg muscles (TA, Gastrocnemius Medialis, Gastrocnemius Lateralis) exhibited elevated but non significant changes. These preliminary findings demonstrate a method for identifying target muscles to prioritize in exoskeleton support for walking-to-climbing transitions.

Date

7-11-2025

Committee Chair

Wang, Chao

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