Revolute joint

Mechanism (biology)

Quantum mechanics

Robot

Control (management)

Engineering

Materials science

Control engineering

Computer science

Mechanical engineering

Physics

Degrees of freedom (physics and chemistry)

Contact force

GRASP

Underactuation

Artificial intelligence

Composite material

Tactile sensor

Finger joint

Programming language

Control theory (sociology)

Workspace

Grippers

Computer vision

IEEE Transactions on Robotics

The ability to grasp a wider range of objects in size and shape directly relates to the performance of robotic grippers. Adapting to complex geometries of objects requires large degrees of freedom to allow complex configurations. However, complexity in controlling many individual joints leads to introduction of underactuated mechanisms, in which traditional finger designs composed of revolute joints allow only flexion/extension motions. In this article, we propose a length-adjustable linkage mechanism in the underactuated finger controlled by an antagonistic tendon pair. The resulting gripper can elongate the fingers for an increased task space or shorten them for a finer spatial resolution. For tactile sensing, hyperelastic soft sensors are used to stretch with finger elongation. Contact pressures measured by the soft sensors are used in force-feedback control for which either the joint angles or the link lengths are adjusted. Lastly, a multimodal control scheme that combines elongation and flexion modes is demonstrated with tasks of dexterous manipulation.

Elongatable Gripper Fingers With Integrated Stretchable Tactile Sensors for Underactuated Grasping and Dexterous Manipulation