What mechanical device did Leonardo da Vinci design to move without a driver?

Leonardo da Vinci designed a self-propelled cart that could move without a driver.

The cart is recorded in drawings from the late 15th century. Springs wound inside its mechanism supplied the stored energy, while a system of gears controlled the wheels. A programmable system of blocks or pegs could determine the route, making the cart an early example of a mechanical vehicle with preset motion.

The original cart was not known to have survived, and Leonardo's drawing leaves some construction details uncertain. Engineers and historians have built reconstructions to test how the mechanism might have worked. In 2006, an Italian team created a working model based on Leonardo's plans.

The cart is sometimes called a robot or automobile, but those labels can mislead. It had no engine and could not make decisions. Its importance lies in combining stored mechanical energy, programmed movement, and wheeled transport in one Renaissance design.