Legged Robot with Tensegrity Feature Bionic Knee Joint

Abstract

Legged robots, designed to emulate human functions, have greatly influenced numerous sectors. However, the focus on continuously improving the joint motors and control systems of existing legged robots not only increases costs and complicates maintenance but also results in failure to accurately mimic the functionality of the human skeletal‒muscular system. This study introduces a bionic legged robot structure that leverages the tensegrity principle, drawing inspiration from the human leg's structural morphology and kinematic mechanisms. By designing a system that distinguishes between rolling and sliding movements, the human knee's variable instantaneous center of rotation (ICR), is successfully replicated showcasing its capabilities in achieving gait resemblance and vibration absorption. The tensegrity unit's features, including remarkable deformability, self-recovery, and the four-bar mechanism's singular position characteristic, alongside a rope unlocking mechanism reminiscent of human muscles, facilitate in situ compliance-rigid-compliance transitions of the knee joint without the need for knee joint motors, relying solely on ground contact through the foot. This innovation overcomes the conventional dependency of legged robots on joint motors, as the system requires only a single DC motor positioned at the hip joint and a straightforward control program to seamlessly execute a complete cycle of a single leg's movement.