Synthesis of a passive knee exoskeleton through multibody kinematics optimization considering wearing uncertainties and kinematic response smoothness

<p indent="0mm">Wearing uncertainties, such as exoskeleton slippage, multidegree-of-freedom knee joint motion, and variations in body geometry, can cause mismatches between the exoskeleton and limb movements. These mismatches may result in unexpected interaction forces in the wearing area, negatively affecting human-machine collaboration. Rapid changes in the velocity of exoskeleton components can complicate interactions further. To address these issues, a passive knee exoskeleton with adaptive compensation for uncertainties has been proposed. Additionally, a response interval model with multidimensional uncertain parameters was developed using the Chebyshev interval method to enhance human-machine collaboration. This model incorporates real-world uncertainties in the analysis of a human-machine research prototype. Furthermore, a new kinematic performance metric called “kinematic response smoothness” was introduced to evaluate the smoothness of exoskeleton configuration parameters objectively. Based on the system’s velocity Jacobian matrix, this metric improves human-machine collaboration by assessing the smoothness of exoskeleton movements. Using this metric and the response interval model, a multiobjective optimization of the system’s kinematics was performed. The results demonstrated that integrating kinematic response smoothness as an optimization metric, alongside response interval range, significantly enhanced the exoskeleton’s kinematic performance after optimization. This reduced the impact of uncertainties on system response. Notably, optimizing motion smoothness, rather than solely focusing on response interval range, significantly enhanced performance. These findings validate the rationality and effectiveness of the proposed method. The study establishes a theoretical framework and provides empirical evidence to support further research on system dynamics and the development of advanced physical prototypes, with broader implications for wearable devices in diverse fields.