Modeling and Dynamic Simulation of an Automated Exercise Bed's Swing-Board Mechanism for Recuperating Patient

Abstract

This study aimed to dynamically model and optimize the Swing-Board Mechanism of an automated Exercise bed's for patient rehabilitations, addressing the global shortage of physiotherapists and the need for safe, autonomous therapy. Using a four-year link configuration with initial dimensions of AB = 150 mm, BC = 400 mm, CD = 350 mm and AD = 500 mm, the research applied Lagrangian mechanics and numerical optimization to derive motion equations and assess forces, velocities and stresses. Optimized link lengths (AB=122 mm, BC = 326 mm, CD = 285 mm and AD = 375 mm) produced a smooth vertical stroke of 0.463 m at 0.318 Hz, with peak velocity and acceleration kept below safety thresholds of 1 m/s and 3.2 m/s^2, respectively. Static and dynamic analyses using 6061 aluminium revealed a maximum Von Mises stress of 28.45 MPa and safety factors between 9.7 and 15.2, ensuring structural integrity. The model demonstrated high energy conservation with variation of 0.023 J/cycle and periodicity of 99.97% cycle match. The study uniquely integrates dynamic optimization with therapeutic motion profile, offering a cost-effective design alternative to imported systems. A limitation includes the assumption of idealised patient loading, thus further validation with human subjects is recommended.