Design features in human joints with recommendations for humanoid robot design

There are many types of moveable joint in the human body, with each characterised by compactness and high functionality. In contrast, humanoid robots typically use just three or four simple types of joint that are relatively bulky with limited functionality. Therefore, there is significant potential for bioinspired design. The paper describes 14 different types of moveable joint in the human musculoskeletal system and describes important design features such as linkage mechanisms, suspension systems and segmentation. In each case, recent examples of bioinspired design or potential for bioinspired design are given. Results are tabulated for ease of reference by designers. The paper highlights key future goals for humanoid robotics such as replicating the MTP joints of the foot, replicating the push-retract motion in fingers and replicating the compact linkage pronation mechanism of the wrist. Human joints exhibit design principles that are quite different to those of traditional engineering such as high degrees of freedom, redundant actuation and multisensory integration. These strategies have potential to inspire a different and more effective approach to the mechanical design of humanoid robots.