What wheeled machine did Leonardo da Vinci design to move automatically using wound springs?

Leonardo da Vinci designed a self-propelled cart to move automatically using wound springs.

The cart was a three-wheeled mechanism powered by coiled springs, rather than by a person or animal pulling it. Cams helped control the movement of the front wheel, allowing the machine to follow a programmed route. Leonardo’s drawings suggest that it may have been intended for theatrical performances or court ceremonies.

The cart is sometimes described as an early robot or an ancestor of the modern automobile. Those labels are useful comparisons, but they can mislead: the machine did not use an engine, steering wheel, fuel, or electronic controls.

A full-size reconstruction was built in the 21st century and demonstrated that the mechanism could operate. The reconstruction also helped researchers study how Leonardo’s compact spring-and-cam system may have worked.