BLT Gripper: An Adaptive Gripper With Active Transition Capability Between Precise Pinch and Compliant Grasp

• Published in: IEEE robotics and automation letters Vol. 5; no. 4; pp. 5518 - 5525
• Main Authors: Kim, Yong-Jae, Song, Hansol, Maeng, Chan-Young
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.10.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive grippers; Belts; compliant mechanisms; Couplings; Degrees of freedom; End effectors; Force; Grasping; Grasping (robotics); Grasping force; grasping mode transition; Grippers; Pressure measurement; robotic hands; Robots; Stability; Stress concentration; Tactile sensors (robotics); Tendons
• ISSN: 2377-3766; 2377-3766
• DOI: 10.1109/LRA.2020.3008137

Achieving both the precise pinching and compliant grasping capabilities is a challenging goal for most robotic hands and grippers. Moreover, an active transition between the pinching pose and the grasping pose is difficult for limited degrees-of-freedom (DOF) hands or grippers. Even when using high DOF robotic hands, it requires a substantial amount of control effort and information from tactile sensors. In this letter, a 3-finger, 5-DOF adaptive gripper with active transition capability is presented. Each finger is composed of a minimum number of components using one rigid link, one belt, one fingertip frame and one motor for flexion motion. This simple and unique finger structure enables precise parallel pinching and highly compliant stable grasping with evenly distributed pressure. The other two motors are used for fingertip angle adjustment and change of the finger orientation respectively. Thorough kinematic and force analysis with detailed descriptions of the mechanical design clearly shows controllable transition property and stable grasping performance. The experiments including the grasping force and pressure measurement verify the performance of the proposed gripper and prove the practical usefulness for real-world applications.