Development of Continuum Spine Mechanism for Humanoid Robot: Biomimetic Supple and Curvilinear Spine Driven by Tendon

In this paper, we developed, for humanoid robots, a lightweight spine mechanism that deforms flexibly, drawing continuous curves. This mechanism is the one that mimics the human musculoskeletal structure. Although the human spine has a high degree of freedom and is difficult to control, our mechanism solves the degree of freedom problem with a tendon-driven underdrive mechanism that applies the technique of continuum robots, and with only nine motors, the basic operations of flexion, extension, lateral flexion and rotation are all realized for each of the three curves, i.e., the cervical spine, thoracic spine, and lumbar spine. A slender and lightweight mechanism combining coil springs and CF (Carbon Fiber) rods is driven by pulling 24 threads, and these threads are allocated to a total of 9 motors. The reproducibility of the basic motions of the human spine, such as flexion, extension, lateral flexion and rotation, was shown by actual machine tests. As an example, we reproduced ‘arabesque’ which is one of the typical ballet postures.