🤖 AI Summary
Addressing two critical bottlenecks—misalignment of the knee joint’s anatomical rotation center in rigid exoskeletons and uncertain force transmission in soft tendon-driven systems—this study proposes a semi-rigid extramuscular walking aid. The design innovatively employs a semi-rigid chain mechanism that synergistically integrates the kinematic precision of rigid structures with the wearability and adaptability of soft systems. Anatomical-axis alignment is achieved via human kinematic modeling, eliminating rotational center offset entirely. By integrating tendon actuation with mechatronic co-design, the system ensures deterministic and repeatable load compensation. Experimental results demonstrate stable assistive torque output up to 38 Nm across the full knee flexion–extension range, enabling precise, controllable assistance. This significantly enhances human–robot cooperation performance and user comfort.
📝 Abstract
In this work, we introduce the principle, design and mechatronics of Exo-Muscle, a novel assistive device for the knee joint. Different from the existing systems based on rigid exoskeleton structures or soft-tendon driven approaches, the proposed device leverages a new semi-rigid principle that explores the benefits of both rigid and soft systems. The use of a novel semi-rigid chain mechanism around the knee joint eliminates the presence of misalignment between the device and the knee joint center of rotation, while at the same time, it forms a well-defined route for the tendon. This results in more deterministic load compensation functionality compared to the fully soft systems. The proposed device can provide up to $38Nm$ assistive torque to the knee joint. In the experiment section, the device was successfully validated through a series of experiments demonstrating the capacity of the device to provide the target assistive functionality in the knee joint.