Unimate The 1961 Unimate installed at a General Motors factory differed significantly from George Devol's 1954 patented design. The Unimate was a
hydraulically actuated programmable
manipulator arm with 5
degrees of freedom. This contrasted with the simpler three-prismatic-link pick-and-place arm described in Devol's "Programmed Article Transfer" (PAT) patent.
Devol's patent Devol's earlier methodology, involving the conversion of analog information into electrical signals, formed the basis for subsequent patents. The patent proposed a cost-effective, general-purpose article-handling machine for diverse industrial tasks, with programmable motions, including gripping mechanisms. It would have a wheeled chassis on rails, a base unit housing the movement-recording program drum, an elevator for vertical arm translation, a telescoping arm with a transfer head and gripper, and a three-dimensional position-sensing system using encoders and sensing heads. The position-sensing system (proprioception) had two versions: one using notched metal strips and ferrous material detection, the other, a magnetized plate with polarity-based sensing and recording. Similarly, the program drum had two forms: a malleable metal sheet with mechanically deformed bulges, and a solid magnetizable drum. Both drum types used corresponding reading mechanisms. The robot could be programmed by manually moving the gripper, recording the location on the program drum, then it could perform the same motion, an early form of
imitation learning. This resulted in point-to-point movement, a standard feature in modern robotic arms. The magnetizable drum also allowed recording continuous movements along curved paths, synchronized with a timing reference for playback. The fixed
encoder array on the base unit served as a location index for recording, enabling deceleration near programmed positions and self-correction during operation. ==In popular culture==