What Leonardo da Vinci machine used a spring-powered mechanism to move without a driver?

Leonardo da Vinci designed a self-propelled cart that used spring-powered mechanisms to move without a driver.

The cart is described in drawings from around 1478 to 1480. Two symmetrical leaf springs, wound with a key, supplied stored energy to the wheels through gears. Steering could be set in advance, allowing the cart to follow a predetermined path rather than being controlled continuously by a person.

The machine may have been intended for theatrical performances or court spectacles. It was not a motor vehicle in the modern sense: it carried no engine or fuel, and its movement was limited by the energy stored in the springs. Modern reconstructions have shown that the design can operate when built carefully.

The cart is sometimes called Leonardo’s automobile, but “self-propelled cart” avoids suggesting that it was a practical modern car. It is one of the earliest known designs for a programmable moving machine.