What self-moving machine did Leonardo da Vinci design using springs and gears?

Leonardo da Vinci designed a self-propelled cart using springs and gears.

The cart was drawn in the Codex Atlanticus and is generally dated to the late 15th century. Large coiled springs stored energy, while a gear system transferred that energy to the wheels. A steering mechanism could be programmed through a wooden peg system, allowing the cart to follow a predetermined path.

Because it moved without being pushed by a person or pulled by an animal, the design is often called an early automobile or robot. It was not powered by an internal-combustion engine, however, and it could travel only a limited distance before the springs unwound.

The cart may have been intended for theatrical performances at a court rather than transportation. In 2006, a replica was built in Florence and demonstrated that the basic mechanism could operate when constructed according to Leonardo’s drawings.