Take another look at robotic locomotion and morphology!
Selecting gaits for economical locomotion of legged robots
This paper explores the benefits of using multiple gaits in a single robot.
Weitao Xi, Yevgeniy Yseilevskiy, C. David Remy
Sage journals
Research on the simultaneous optimization of motion and morphology; comparing different actuators in legged robots:
A comparison of series and parallel elasticity in a Monoped hopper
Optimal configuration of series and parallel elasticity in a 2D Monoped
The video of the comparison: