Grippers and Grasp Types

No single gripper handles everything. A parallel jaw is simple and precise but needs two flat sides. Suction is fast but needs a smooth, sealed surface. Multi-finger hands wrap around odd shapes but are complex. Soft grippers conform to fragile objects. Warehouse robots often carry several and pick per object.

Gripper Object

What each grasp relies on

A parallel jaw squeezes two opposite surfaces and relies on friction, so it needs two roughly parallel faces narrower than its opening. Suction holds with a pressure difference over the cup's area, so it needs a smooth surface that seals:

$$F_{\text{suction}} = \Delta p \cdot A_{\text{cup}} \qquad F_{\text{friction grip}} = 2\,\mu\,F_{\text{squeeze}}$$

Multi-finger hands can cage or wrap an object. Soft grippers conform to the shape and spread the force.

What to notice

The flat plate defeats the parallel jaw, since there is nothing to pinch from the top, but suction lifts it easily. The crumpled bag of chips leaks air, so suction fails, while the soft gripper handles it gently. The mug is easiest by its handle, a job for fingers. Picking systems in warehouses often score every gripper on every object, much like this table, and switch tools as needed.