Joint device

Variable Axis Joint Device with Self-Alignment via Tensegrity Strings and Leg-Roller Sliding

This technology features a joint assembly composed of multiple independently rotatable frames, connected by a tensegrity-structured string system and a leg-roller-based sliding mechanism to achieve self-aligning joint movement with a variable axis of rotation.

Conventional rigid-body joints have fixed axes of rotation, making it difficult to replicate the complex combination of rotation and sliding found in human joints. They also suffer from issues such as user discomfort due to a lack of flexibility under external impact, mechanical wear from friction, and weight burdens during prolonged wear.

This technology maintains force equilibrium through the sliding movement of connecting legs and the tensegrity structure of the string members. This ensures rotational flexibility in yaw, roll, and pitch directions while minimizing friction and wear through a non-contact frame structure. It is ideal for wearable robots, rehabilitation aids, and exoskeleton systems, as it naturally mimics human joint movement and reduces the burden on the wearer.

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Key Features:

• Upper and lower mounts that are attached to adjacent body parts around the joint and spaced apart from each other
• A joint assembly that connects the upper and lower mounts and includes a plurality of sequentially arranged frames
• First through fourth string members configured to connect adjacent frames to form a tensegrity structure
• A string connection unit including a first point where the first and second string members are connected, and a second point where the third and fourth string members are connected

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of a 50Nm/kg high-torque-to-weight ratio low-voltage drive module series for wearable robots.