The actuator is in the form of a helical spring. The helical spring in this case has an S-shaped cross-sectional profile and is constructed in such a way that the respectively lower edge overlaps the respectively upper edge of an adjacent spring turn. Tension cables which are guided along eyes on ...http://www.google.fr/patents/US5842381?utm_source=gb-gplus-shareBrevet US5842381 - Precisely controllable flexible actuator
