Evolution of an amphibious robot with passive joints

Passive joints provide a means to reduce the mechanical complexity of a robot because they do not require direct actuation from a motor. However, the inclusion of such components complicates the development process, as their behavior is highly dependent on external stimuli in combination with actuation of other components. In this paper, we describe a study on the evolution of morphological characteristics and controller parameters for an amphibious robot with passive arm joints. Results show that this approach is able to exploit the properties of passive joints, producing effective locomotion in both aquatic and terrestrial environments. Evolved solutions demonstrate a strong coupling between fin morphology and control strategy with respect to performance.