Why a giraffe cannot walk like a dachshund

At first they can hardly move forward, then they start to crawl and finally – after having stood up straight by themselves for the first time – they are filled with sheer enthusiasm about walking.

“The way children learn how to walk is quite similar to the evolutionary transition from the four-legged to the two-legged gait”, says Dr. André Seyfarth from the University of Jena.

Together with an international team of researchers he tries to find out how this transition works mechanically. Therefore a cooperation project has been started with colleagues from Switzerland, Belgium, Denmark and Canada. It is funded with EUR 2.7 million by the European Commission for the next four years. Dr. Seyfarth's team in Jena receives EUR 515.000 of it.

Locomorph is the new project's name – deriving from the words locomotion and morphology. This literally means shape of movement. And that is exactly what André Seyfarth aims at: “We want to understand the mechanical and neuronal communication in the moving leg – in order to copy it.” The construction of modular walking robots which help to imitate the development from the four-legged to the two-legged locomotion is planned as the last of the project's three parts. But beforehand the scientists have to analyse and study movement as well as to develop computer models.

At the Jena Locomotion Laboratory now the movement of test persons on a treadmill is going to be examined. Specially fitted orthoses are also being used for that. They are normally used for supporting parts of the body that are limited in function, for example for stabilising joints after a sporting accident. “The mechanics of our orthoses have been rebuilt in such way”, explains André Seyfarth, “that we can imitate typical movement programs from the outside. The body then can signal us if the programme is perceived in a positive or negative way”. Thus the researchers are able to find out if this is the natural state already or if they must go on searching for the right solution. “So to speak, we go the other way around. We try to explain biological matters by identifying basic mechanisms and offering them to the body”, says Seyfarth.

In addition to the analyses of the Jena team the colleagues in Belgium take similar measurements with lizards, primates and toddlers. “From this we hope for an exact image of the movement patterns at the transition from the four-legged to the two-legged gait”, explains Seyfarth.

On the basis of these data the scientists want to develop a computer model which could then be converted into a technical system. Therefore several walking robots are constructed which allow the imaging and testing of such movement models. The advantage of a technical system is obvious for team leader André Seyfarth: It can be touched and changed, and it examines the reaction caused by the change. “In this way we come closer to the real processes of human motion step by step.”

The project's goal is to create a tool by means of robotics which depicts and explains the different human and biological stages of development of the movement morphology. This makes it possible to develop individual therapies and prostheses for patients with motor dysfunctions or leg amputations. Each human being has a very individual gait. That is why Seyfarth considers the traditional method of comparing individual movement patterns to normative reference curves unfavourable. It simply cannot depict the individual motions of a certain body. “If a giraffe is forced to walk like a dachshund it will always remain unhappy since the giraffe simply cannot realise it”, Seyfarth explains the problem.

“In four years”, he hopes, “with the help of the research results, we might already have established a better basis for the treatment of motor disorders, for instance after an accident. Such treatment could take into consideration the individual morphological preconditions for the locomotion of a single patient.”

Contact:
Dr. André Seyfarth
University of Jena
Institute of Sport Science
Dornburger Str. 23
D-07743 Jena
Phone: +49-3641-945730
Email: Andre.Seyfarth[at]uni-jena.de