Optimal Kinematic Synthesis and Prototype Development of Knee Exoskeleton

TL;DR

This paper designs an optimal one-degree-of-freedom knee exoskeleton to enhance range of motion for rehabilitation, using kinematic analysis and prototype development, achieving a 24% improvement over previous designs.

Contribution

It introduces a novel optimization approach for knee exoskeleton design based on human leg measurements and validates the design through prototype development.

Findings

Range of motion increased by 24% in simulation

Misalignment study shows improved joint trajectory matching

Prototype confirms maximum range of motion during sit-to-stand

Abstract

The range of rotation (RoR) in a knee exoskeleton is a critical factor in rehabilitation, as it directly influences joint mobility, muscle activation, and recovery outcomes. A well-designed RoR ensures that patients achieve near-natural knee kinematics, which is essential for restoring gait patterns and preventing compensatory movements. This paper presents optimal design of one degree of freedom knee exoskeleton. In kinematic analysis, the existing design being represented by nonlinear and nonconvex mathematical functions. To obtain feasible and optimum measurement of the links of knee exoskeleton, an optimization problem is formulated based on the kinematic analysis and average human's leg measurement. The optimized solution increases the range of motion of knee exoskeleton during sit to stand motion by $24 \%$ as compared with inspired design. Furthermore, misalignment study is conducted by comparing the trajectory of human's knee and exoskeleton's knee during sit to stand motion. The joint movement is calculated using marker and camera system. Finally, a prototype of the knee joint exoskeleton is being developed based on optimal dimensions which validate the maximum range of motion achieved during simulation.