What Leonardo da Vinci invention used a spring-powered mechanism to move without a person pushing it?

Leonardo da Vinci designed a self-propelled cart powered by a spring mechanism.

The cart appears in drawings from the late 15th century. Coiled springs stored energy, and a system of gears and cables transferred that energy to the wheels. Adjustable cams could program the cart’s path, allowing it to move forward and perform a controlled turn rather than simply roll freely.

The machine is sometimes described as an early robot or as a predecessor of the modern automobile. Those descriptions need care: it had no engine, no steering wheel and no passenger cabin, and it was never known to have been built in Leonardo’s lifetime. It was an automaton designed to move by itself for a limited programmed sequence.

A replica built for a 2006 television documentary demonstrated that the surviving drawings could produce a working version. The cart may have been intended for theatrical or ceremonial use, perhaps to carry a figure or create a dramatic effect at a court event. Its key innovation was programmable mechanical motion.