What type of transport did Leonardo da Vinci sketch with a spring-powered mechanism and three wheels?

Leonardo da Vinci sketched a spring-powered self-propelled cart.

The design appears in Leonardo's Codex Atlanticus and is generally dated to the late 15th century. It used coiled springs to store energy, while a system of gears controlled the release of that energy to the wheels. The cart had three wheels and could be set to follow a predetermined route.

Because it could move without a person pushing or pulling it, the machine is often called an early automobile or robot. It was more accurately a programmable theatrical device: adjustable components could determine its path, making it useful for court performances and pageants.

A working reconstruction was built in 2006 by Italian researchers and displayed at museums. The original drawing does not prove that Leonardo built the cart himself.