  Under-actuated robot grippers as a pervasive tool of robots have become a
considerable research focus. Despite their simplicity of mechanical design and
control strategy, they suffer from poor versatility and weak adaptability,
making widespread applications limited. To better relieve relevant research
gaps, we present a novel 3-finger linkage-based gripper that realizes
retractable and reconfigurable multi-mode grasps driven by a single motor.
Firstly, inspired by the changes that occurred in the contact surface with a
human finger moving, we artfully design a slider-slide rail mechanism as the
phalanx to achieve retraction of each finger, allowing for better performance
in the enveloping grasping mode. Secondly, a reconfigurable structure is
constructed to broaden the grasping range of objects' dimensions for the
proposed gripper. By adjusting the configuration and gesture of each finger,
the gripper can achieve five grasping modes. Thirdly, the proposed gripper is
just actuated by a single motor, yet it can be capable of grasping and
reconfiguring simultaneously. Finally, various experiments on grasps of
slender, thin, and large-volume objects are implemented to evaluate the
performance of the proposed gripper in practical scenarios, which demonstrates
the excellent grasping capabilities of the gripper.
