gripper

A gripper is the robot's hand — the device at the very end of an arm whose whole job is to take hold of an object and not let go until told to. If the arm is what reaches, the gripper is what grasps. It is one kind of end effector, the swappable tool a robot wears at its wrist, and it is the part that finally touches the work: closing around a bottle, pinching a screw, or cradling an egg without crushing it.

The most common design is the parallel-jaw gripper: two flat fingers that slide straight toward each other to clamp an object from two sides, like a small powered vise. It is simple, strong, and reliable, but it only really knows one move — squeeze. A multi-fingered gripper, by contrast, has three or more jointed fingers that can curl and spread, wrapping around oddly shaped things the way a human hand does and even rolling an object between its fingertips. More fingers and joints mean more shapes it can hold, but also more motors to drive and more decisions to plan.

Choosing a gripper is mostly about matching it to the objects and the touch they need. Jaws can be wide or narrow, hard steel or soft rubber, fast or gentle; many add a touch sensor so the robot can feel how firmly it is holding and stop before it slips or breaks. The grip a robot picks — where to place the fingers and how hard to press — is called the grasp, and a good gripper is one that makes a wide range of safe, steady grasps easy.