What Leonardo da Vinci invention is commonly described as an early self-propelled cart?

Leonardo da Vinci’s early self-propelled vehicle is commonly called the self-propelled cart.

Leonardo designed the cart around 1478–1480. Springs wound inside the vehicle supplied its power, while programmed cams controlled the rotation of the wheels. The mechanism could make the cart move without a person pushing it, making it an important early example of a programmable mechanical device.

The cart may have been intended for theatrical use or ceremonial display rather than transportation. Its compact design and hidden mechanism would have allowed it to appear to move by itself during a performance. Leonardo’s drawings did not preserve every construction detail, so modern reconstructions have had to interpret parts of the design.

The cart is sometimes called a robot in popular accounts. That label is useful as a comparison, but it was not an electronic robot and could perform only a pre-set movement.