Grippers

Investigator: Josephine Selvarani Ruth D. (RBCCPS)

Robot grippers are the physical interface between a robot arm and the work piece or a human. To design and develop robotic arms and grippers, we integrate the following factors:

  • Coupling, collocation & compliance
  • Instrumenting smart materials
  • Human-robot-interaction

Our work focuses currently on tri-fingered, parallel-jaw, and flexible fingers.

Tri-fingered gripper: The three fingers of the robotic gripper are pivoted to the palm in away that allows executing the grasping configurations without changing the orientations of the finger bases. The fingers are attached in a circular way with 120 degrees between each other. This allows the worm wheels of the fingers to be driven from a single actuator via the actuating worm. This type of the finger placement is better for grasping spherical or cylindrical objects of different sizes.


Parallel-jaw gripper: Improved parallel-jaw grippers with four fingers are optimal for positioning square work pieces as well as picking up round objects. This allows the crank mechanism of the fingers to be driven from a single servo actuator via the actuating worm. Its wedge cam design minimizes its overall size while retaining a high holding force, thus making it suitable for end-of-arm (end effector) or space constrained pick and place applications.



Flexible Gripper: Flexible grippers have some advantages over rigid ones when used in grasping tasks. They absorb energy during the impact, which make them suitable in delicate manipulation or human interaction.

The presence of a minimum of potential energy in an equilibrium point implies a stable grasp. The potential function around an equilibrium point determines the basis of attraction and permits us to study the influence of scale between the size of the gripper and the grasped object, stiffness, preload and pre-curvature of the elastic fingers on the grasp stability.

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