Modular design of 7-DOF cable-driven humanoid arms

With the rapid development of AI, it is prospective for humanoid robots to be applied for various social and home services. And humanoid robots for services demand excellent performance with anthropomorphic bodies besides AI. Take the dual arms for example, they are desired to be dexterous and light-weighted for mimicking human arm motion, which is hard to be satisfied by traditional design. To this end, we have designed novel humanoid arms with unconventional design method in this paper. With seven degrees of freedom (DOFs) according to human arm anatomy, each of our humanoid arm is composed of three parts, which are the shoulder with three DOFs, the elbow with one DOF, the wrist with three DOFs, and the hand. Each part is designed as one module. Since the shoulder and the wrist have the same configuration and DOFs, they are actually of the same type of module but with different size and power. They are implemented with parallel mechanisms, and most of the joints are driven with cables for light weight. In this way, one arm is composed of four modules of three types, which are the shoulder, the elbow, the wrist and the hand. With the modularity design, it is trivially to compose the right and left arms with the same modules, and may be with different lengths of the arms mimicking different persons, which would be largely beneficial for mass production with relatively low costs. The design method, the structure design of the modules are presented in this paper. Kinematic simulation of the arm is carried out to simple show its kinematic performance.