End-effector

The end-effector is the terminal device on a robot arm that interacts with the world. In humanoids, typically a multi-fingered hand; in industrial settings, a parallel-jaw gripper, suction cup, welding torch, or specialized tool. Distinct from the wrist (the joint subsystem connecting arm to end-effector) and the arm itself.

End-effector choice is the single most consequential mechanical decision after form factor. A humanoid with a five-fingered hand can be evaluated for dexterous manipulation; one with a parallel gripper cannot, regardless of the rest of the body. The DOF count, fingertip force, contact-sensor density, and actuation architecture of the end-effector are the numbers that determine what work the platform can actually do.