What self-moving invention did Leonardo da Vinci design around 1478 for theatrical performances?

Leonardo da Vinci designed a self-propelled cart around 1478, probably for theatrical performances and moving scenery.

The cart used coiled springs inside drums to store energy. As the springs unwound, gears transferred motion to the wheels. A steering mechanism could be set in advance, allowing the cart to follow a predetermined path rather than being driven by a person.

The invention is sometimes called an early automobile because it moved without an animal or human pushing it. That comparison is useful only in a limited sense: Leonardo’s cart had no engine, fuel system, brakes, or flexible steering like a modern car.

The surviving drawing was incomplete, and the exact mechanism was reconstructed from Leonardo’s notes. In 2006, researchers at the Institute and Museum of the History of Science in Florence built a working replica, confirming that the basic concept could operate.