What self-moving device did Leonardo da Vinci sketch around 1478, often regarded as an early robot?

Leonardo da Vinci sketched a self-propelled cart around 1478, often regarded as an early robot or programmable machine.

The cart used coiled springs to store energy. As the springs unwound, gears transferred the motion to the wheels, allowing the vehicle to move without being pushed. A steering mechanism could be set in advance, so the cart followed a predetermined path rather than responding to a driver.

The machine was probably intended for theatrical or ceremonial use, possibly to surprise guests at court events. It was not an automobile because it had no engine, fuel system, or occupant. In 2006, researchers and builders created a working replica based on Leonardo’s drawings. The reconstruction helped demonstrate that the basic mechanism could operate, although interpreting the incomplete sketches required engineering judgment.