Bionic concept and synthesis methods of the biomimetic robot joint mechanism for accurately reproducing the motion pattern of the human knee joint

The human knee joint (HKJ) exhibits a complex motion pattern characterized by a coupling of rolling and sliding movements as well as a moving instantaneous center of rotation. Reproducing this motion pattern in robot joints holds significant scientific and engineering value. This paper addresses two primary challenges in the bionic design of the biomimetic robot joint (BRJ): the difficulty in accurately reproducing the required motion and the absence of systematic structural synthesis methods for joint mechanisms. Firstly, a bionic concept is proposed to develop novel BRJ mechanisms based on the in-depth analysis and understanding of the HKJ, which realizes accurate reproduction of the HKJ motion pattern by introducing the higher pair. Then, task-oriented synthesis methods are further investigated to find innovative design solutions in a systematic and efficient way, including the profile synthesis of the higher pair and the structural synthesis of the overall mechanism. Finally, a case study of the four-link BRJ mechanism validates the effectiveness of the proposed method, resulting in innovative design schemes with potential applications.