Dislocation Analysis on Bio-inspired Open Hip Joint with Active-and-Passive Stabilizers.

This study presents a simulator framework to replicate joint dislocation that can be used to evaluate the contributions of various joint stabilizers. Compared to conventional axial joint configurations, biologically inspired open joints allow for a large range of motion with fewer rotational components and no singularities. Despite these advantages, open joints have few practical applications due to joint dislocation. To facilitate the development of bio-inspired open joints, our study evaluates the performance of biomimetic joint stabilizers involving (1) the muscle actuators as the active stabilizer, and (2) the skeletal socket and the ligaments as the passive stabilizers. Those stabilizers exert appropriate constraint forces during joint motion to prevent dislocation. The convex decomposition of the skeletal socket enabled the simulation of the dislocation behavior. The kinematic simulation determines the ligaments' maximum length depending on the desired joint motion. The designed ligaments were suggested to prevent excessive dislocation in the simulation even when the motor output was off. The comparative simulation analysis also indicated that socket depth, active stabilizer, and passive stabilizer had different contributions for dislocation prevention and recovery. Future work includes the experimental verification of the proposed open hip joint architecture.