  This study proposes a novel robotic hand that can achieve self-adaptive
grasping and a large payload (over 20 kg) with a single actuator. Accordingly,
two novel mechanisms, an actuation system with self-motion switching and a
self-adaptive finger with a self-locking mechanism, are installed in a
1-degree-of-freedom robotic hand. The actuation system switches the output
motion from translational to rotational according to the applied external load.
The finger is bent by inserting a flexible shaft inside it. Its bending posture
can conform to the shape of the object owing to the flexible shaft, and the
posture is fixed by a self-locking mechanism, which can be released by the
rotational motion of the actuation system. This study presents a mechanical
analysis of these mechanisms to achieve the desired behavior. The analysis was
validated experimentally, and a robotic hand with these mechanisms were
evaluated using grasping tests.
