Tensegrity Sensor-Integrated Hip Exoskeleton for Human Motion Recognition During Walking

Abstract

This paper proposes a hip exoskeleton inspired by the concept of biotensegrity. An actuator directly connected to a rigid structure is applied to provide a high assistive torque for flexion and extension in the sagittal plane. In the frontal and transverse planes, where lower torque is sufficient, passive joints based on tensegrity structures are introduced to mimic the flexibility and load distribution of the human musculoskeletal system. In particular, a novel passive joint mechanism is structurally extended into a universal joint that functions as a joint angle sensor, enabling the quantitative measurement of the wearer’s hip complex motions during walking. To validate this mechanism, five linear parameters are extracted using line geometry to analyze its universal joint behavior mathematically. Specifically, the change in resistance of the rubber band inside the sensor is used to calculate the joint kinematics, that is, it is used to estimate the rotation axis and angle based on a line geometry. Finally, comparative experiments with actual joint angles are conducted, confirming that the three-degrees-of-freedom motion of the wearer’s hip complex can be effectively recognized using the tensegrity sensor-integrated hip exoskeleton.