During the design process of the walking robot ALDURO virtual prototyping is used to test the design studies in a computer simulation, where the different parts can be tested under various conditions. It is not suf£cient to have separate models of the mechanical, hydraulic and electronic subsystems. A single detailed mechatronic design approach that incorporates all subsystems, and their in¤uence on each other, is required. For the ALDURO conventional linear controllers do not provide satisfactory results due to the highly nonlinear kinematics and dynamics of the legs. Therefore a nonlinear control concept is under development using a detailed model of the mechanical structure and the method of the exact input/output linearization.