DESIGN OF AN ACTIVE FOOT FOR A SMART PROSTHETIC LEG Vom Fachbereich Maschinenbau an der Technischen Universität Darmstadt zur Erlangung des Grades eines Doktor-Ingenieurs (Dr.-Ing.) genehmigte D i s s e r t a t i o n Vorgelegt von Dipl.-Ing. Valerio Carli aus Rom Berichterstatter: Prof. Dr.-Ing. Holger Hanselka Mitberichterstatter: Prof. Dr.-Ing. Rainer Nordmann Tag der Einreichung: 31.10.2006 Tag der mündlichen Prüfung: 12.12.2006 Darmstadt 2007 D 17 ABSTRACT The purpose of this project is the realisation of a prosthetic foot, able to adapt to the different conditions encountered by the patient during walking. The analysis of the human gait shows that a normal foot has the capability to assume an optimised shape. Coordinated movements of body parts, together with the shape assumed by the foot, result in minimising the energy expenditure during walking. Concerning the prosthetic foot, the bending stiffness of the plantar spring is the quantity to vary, in order to achieve the desired change in foot properties. Three different concepts are investigated: The first one deals with the possibility of adjusting the static response of the plantar spring of the foot by means of solid-state actuators.