A COMPARATIVE ANALYSIS OF LOWER LIMB EXOSKELETON GAIT CONTROL SYSTEMS

Abstract

The complexities associated with lower limb exoskeleton control systems stem from the dynamic and non-linear nature of human movement. Gait control, in particular, requires intricate coordination of joints and muscles, demanding precise adjustments to accommodate variations in walking speed, terrain, and user preferences. Additionally, the diverse physical characteristics among users, such as weight, height, and muscle development, introduce parametric uncertainties that amplify the challenge of designing control systems that can adapt seamlessly to individual differences. Addressing these complexities involves an advanced and multi-level control approach. In the pursuit of effective control strategies, a non-linear mathematical model for a single-leg lower limb exoskeleton is derived, considering mechanical and electromechanical components. Тhe gait control systems of a lower limb exoskeleton were investigated, emphasizing the development of various control strategies, including proportional derivative (PD), PD with gain scheduling, hybrid adaptive, and adaptive controllers with gain scheduling. The article ends with a comprehensive comparative analysis of the developed controllers, presenting the integral absolute errors (IAE) during exoskeleton walking in both load and no-load conditions to evaluate their productivity, efficiency, and adaptability. Extensive testing was conducted using a physical test model representing the exoskeleton of the lower limbs. During a series of experiments, the functionality and operability of each control system were evaluated in various scenarios. The results of these tests give valuable information about the strengths and weaknesses of various control strategies, contributing to the development of lower limb exoskeleton technology.