  To achieve human-like dexterity for anthropomorphic robotic hands, it is
essential to understand the biomechanics and control strategies of the human
hand, in order to reduce the number of actuators being used without loosing
hand flexibility. To this end, in this article, we propose a new interpretation
about the working mechanism of the metacarpal (MCP) joint's extension and the
underlying control strategies of the human hand, based on which we further
propose a highly flexible finger design to achieve independent movements of
interphalangeal (IP) joints and MCP joint. Besides, we consider the
hyperextension of fingertip into our design which helps robotic finger present
compliant and adaptive posture for touching and pinching. In addition, human
thumb muscle functions are reconstructed in the proposed robotic hand design,
by replacing 9 human muscle tendons with 3 cables in the proposed task-oriented
design, realizing all 33 static and stable grasping postures. Videos are
available at https://sites.google.com/view/szwd
