Evaluating the Effect of a Flexible Spine on the Evolution of Quadrupedal Gaits

Animals demonstrate a level of agility currently unmatched in their robotic counterparts. The elasticity of muscles and tendons increase not only performance, but also the efficiency of movements. In contrast, robots are often constructed with rigid components connected by motors. However, recently compliant actuators and materials have been introduced to enhance robot designs, emulating the flexibility of natural organisms. In this paper, we incorporate passive flexibility into the spine of a quadruped animat and employ computational evolution to generate gaits. Results indicate that spine flexibility significantly increases both performance and efficiency of evolved individuals. Moreover, evolving the degree of spine flexibility along with artificial neural network controllers produces the highest performing solutions.