The famous Franconian knight Gottfried (also called “Götz”) von Berlichingen (1480–1562) was born into a time of upheaval during the transition from the late Middle Ages to modern times: Michelangelo (1475–1564), Copernicus (1473–1543), Luther (1483–1546), Paracelsus (1493–1541), and Vesalius (1514–1564) lived almost simultaneously. In 1514, slave shipments from Africa to America began, in 1519–1521 the Aztec empire was conquered, from 1518 to 1525 the plague raged throughout Europe, in 1519 Leonardo da Vinci died, and in 1533 Elizabeth I of England was born. Götz von Berlichingen bravely defended the ideals during the end of chivalry. Fighting numerous battles and engaged in numerous “feuds” with various other knights and even cities, one event is of particular importance for him: During the Landshut War of Succession (1504/05), he lost his right hand due to a cannon ball splinter injury in 1504 at the age of 24 years. The cannon fire came from his own countrymen by accident [1
In his autobiography, which he dictated to a priest at the end of his life, Götz says, “Then a servant came to my mind, of whom I had heard from my father and old … servants, called Köchli, who had had only one hand, and who, in the field, could have done just as well as any other man in the field. I prayed to God and thought to myself, even if I had twelve hands, and his grace and help would not be with me, it would be in vain. That is why I thought that if I had little spare by an iron hand, I wanted to be as efficient as any other frail man in the field” [2
]. Götz already thought about replacing his hand artificially during his time in the sick bay and early on commissioned a gunsmith to build the first “Iron Hand”. In this prosthesis, the artificial thumb and two finger blocks (index and middle finger, and ring finger and little finger, respectively) could be moved in their basic joints by a spring mechanism and released by a push button. Photographs of the first hand can be seen under the following permalinks of the Landesarchiv Baden-Württemberg, Abteilung Generallandesarchiv Karlsruhe:
Some years later, presumably around 1530, a second “Iron Hand” was built. In this, the fingers could be moved passively in all joints. Photographs of the second hand can be seen under the following permalinks of the Landesarchiv Baden-Württemberg, Abteilung Generallandesarchiv Karlsruhe:
Although the second prosthesis was more elaborate than the first prosthesis, it seems that the knight continued to use the first one much more often, as, opposed to the first, the second prosthesis has nearly no traces of usage. However, since only certain things could be held, the environment of Götz had to be adapted in such a way that dealing with the first “Iron Hand” was as simple as possible. In the museum at Jagsthausen, Germany, one can see some of these adapted instruments: his crossbow and his cutlery and travel set.
In 1815, the Basel copper engraver Christian von Mechel (1737–1817) illustrated and described the second “Iron Hand” and its artful mechanics in a detailed book, which contains two aquatint etchings in a scale of 1:1 [3
]. Mechel, who was commissioned to draw the hand, dismantled it for this purpose, but was later unable to put it back together properly; one finger remained stiff and could not be repaired. In the early 1980s, Günter Quasigroch had the chance to inspect both hands and make some drawings from its inside, although he was not allowed to dissemble the hands [4
]. Based on the work of Quasigroch, we reconstructed the first artificial hand by 3D computer-aided design (CAD) and printed it with a multi-material polymer printer. We also adapted some pieces of the mechanics, resulting in mainly three different variants of the hand’s reconstruction.
In this piece, we would like to give a detailed overview on these reconstructions and show the reader further developments that translated the fascinating mechanical Götz prosthesis into a motorized artificial hand.
Please note: For further details on the mechanics, and the used software and hardware, please refer to the cited original research articles and theses. These are not part of this overview.
3. Further Developments
Subsequent to the “Iron Hands” of Götz, many other hand prostheses followed over the centuries. To name only a few: the hand from Eisfeld (16th century); the hand of the Turkish buccaneer Horuk Barbarossa (16th century); the hands of the famous physician Ambroise Paré (16th century); the Balbronian hand, which is quite similar to the second “Iron Hand” of Götz (16th century); the hand from Lamzweerde; the arm built by Carl Heinrich Klingert (end of the 18th century); the hands of Karoline Eichler (c. 1836), the artificial hands of Pfnor (c. 1840); the famous Sauerbruch hand prosthesis (first half of the 20th century); the Krukenberg arm (first half of the 20th century); the prosthesis of Edmund Wilms (Vaduz Hand, 1949), one of the first electromotor-driven prostheses; the pneumatic arm of Häfner (c. 1950); and the “Otto-Bock Elektro-Systemhand” (second half of the 20th century), one of the first myoelectrical prostheses [12
Based on our above 3D polymer reconstructions of the first “Iron Hand” of Götz, we tried to translate some of the ideas of this mechanical passive
prosthesis into a modern motorized active prosthetic hand. One example is shown in this overview, a sensorimotor, controller-controlled intelligent finger system. Another example with a modern motorized four-finger gripper system, whose fingers are ultimately based on the 3D CAD finger data of Götz, is presented in [13
] (see this permalink: https://0-www-nature-com.brum.beds.ac.uk/articles/s41598-020-73250-6/figures/6
Conversion of the Götz Hand to A Sensorimotor, Controller-Controlled Intelligent Finger System
In this work, an intelligent, controller-controlled sensorimotor finger system was reconstructed on the basis of the first “Iron Hand” of Götz. For this, two electronic, servo-motorized fingers, which mimicked the “tweezer grip” and automatically switched off at pre-set contact pressure, were built into the Götz hand chassis (Figure 5
This work showed that it is possible to develop an active hand with simple, commercially available electronic components that can perform convincing gripping functions even in a simple “tweezer grip”. Ultimately, only one on/off command was needed because the hand had programmable pressure sensors that, at a certain pressure, switched off the finger (i.e., the artificial thumb and/or the index finger) moved by a servo motor. The finger then remained in its position due to the locking gear of the servo motor. With the simple pressure sensors, this system worked as a closed-loop system, and we therefore called it the “sensorimotor, controller-controlled intelligent finger system”.
The functionality of this simple system, for example gripping a raw egg or a styrofoam ball between the two fingers, was amazing (Figure 6