The robots of Leonardo Da Vinci

The Codices of the great Leonardo Da Vinci, who besides his numerous talents, was intrigued by the mechanical devices that were being contrived to fascinate the crowds, contain sketches of the mechanisms of three automatons—let’s call them Automated Cart, Mechanical Lion, and Mechanical Knight. It is known that he was reading classic Greek texts and had a keen desire to reproduce the science of ancient masters like Ctesibius and Heron, and perhaps to outdo them. Leonardo continued and advanced his fascination with ancient Greek science by developing fully animated automata.

Automated Cart

The so-called Automated Cart is the first known automaton of Leonardo. The manuscript Codex Atlanticus (largest collection of Leonardo’s sheets) page f812r (see the nearby image) shows his unique technological advances in automation devices from as early as 1478 when Leonardo, still 26 years old, was engaged as an independent artist in Florence and used to work for the local ruler Lorenzo Medici.

Leonardo’s three-wheeled programmable cart has a wooden frame, that measures about 50×50 cm. The cart’s frame is joined by secure fasteners to protect “any mounted” device from the vibrations as the cart moves through its programmed trajectory. The machine has two large gears and arbalest springs, the source of motive power, each an interdependent subsystem for propulsion and guidance. A rocker arm held in tension by cables connected to the arbalest springs created the escapement to regulate the speed of the gears oscillating back and forth. The left unit was felt to be used for propulsion, whereas the right unit was for guidance systems and automation of mounted pieces. The front wheel drive is a rack-and-pinion mechanism for steering with the possibility of serving as a trigger for “special effects.”

The direction and velocity of Leonardo’s automated cart were controlled by an array of cams attached to the top of the large barrel gears. The left propulsion cams controlled the speed of the cart, perhaps even stopping at programmed intervals, turning, or reversing, all of its own volition.

Mechanical Lion

Sheets 90/v (see the nearby image) and 91/r of Leonardo’s Codex Madrid I include drawings of peculiar mechanisms that show detailed functions of a walking apparatus, which is perhaps derived from a design by Leonardo for the movements of a mechanical lion or another automaton. The upper figure on page 90v (marked with 1) is erased, while the lower (marked 2) presents an improved version of the same device, boldly drawn, labeled, and commented: Quando la corda -n-a- sarà disscesa in -n-e-, il piedi -d- si sarà alzato l’altezza di -h-e-. E quando la corda e sarà pervenuta in -f-, il piedi -d- sarà riabbassato. (When the rope -n-a- has descended to -n-e-, the foot -d- will have risen by the height -h-e-. And when the rope has reached -f-, the foot -d- will have descended again.) The lower drawing shows the mechanism’s functions more clearly, although in contrast to the upper only one drive wheel is drawn. This wheel holds the ends of two ropes on the edge (at two points offset at right angles), both leading via the pulleys to a three-part lever mechanism. When the wheel turns, it pulls the levers together and apart with the band, and the limbs move accordingly.

Accounts at the time show Leonardo may have made three such lions. The first automaton was probably designed at the beginning of 1490s, while Leonardo was under the patronage of Ludovico Sforza, the Duke of Milan, and was presented on a royal spectacle for the French King Charles VIII in late 1495, and was later displayed in many public venues including the wedding of Maria de Medici in 1500. A second lion, according to accounts, was somehow self-powered and could walk and move its head. It was presented on 1 July 1509 at the entry of King Louis XII into Milan. The third lion (powered by a counterweight with escapement), a gift from Pope Leone X and the town of Florence to the King of France, Francis I, was taken to Lyon, where on 12 July 1515, at the end of a surprising, magical walk before the King, it stopped, the lion’s body opened and it reared on its hind legs and presented lilies (the fleur de lys is a symbol of French royalty) to the King.

Mechanical Knight

Around 1495, almost at the same time when Leonardo designed his Mechanical Lion, he devised another automaton, the so-called Mechanical Knight. In the 1950s, Italian researcher Carlo Pedretti discovered in the Codex Atlanticus sketches and notes on the Mechanical Knight, with numerous fragmented design details scattered across various pages.

The automaton would have had the outer appearance of a Germanic knight and a complex core of mechanical devices that probably were human-powered. It had two independent operating systems: The first had three degree-of-freedom legs, ankles, knees, and hips; The second had four degrees of freedom in the arms with articulated shoulders, elbows, wrists, and hands. A mechanical analog–programmable controller within the chest provided the power and control for the arms. The legs were powered by an external crank arrangement driving the cable, which connected to key locations near each lower extremity’s joints. The robot’s head has a hinged jaw and is attached to a flexible neck. Drums inside the automaton produce sounds as the rest of the body moves.

The Mechanical Knight appears to have been assembled and displayed for the first time at a ceremony held by the Prince of Milan, Ludovico Sforza in 1495. It doesn’t appear to have made another appearance.

Despite the lack of complete plans, several attempts to reconstruct the Mechanical Knight have been made since its rediscovery in the 1950s. The first real attempt to rebuild the Knight was undertaken by American roboticist Mark Rosheim in 1996 (see the nearby image). This was the first practical demonstration that the automaton worked as planned. Besides that, it appears to follow the laws of proportions and kinetics laid out in Leonardo’s Vitruvian Man.