Template models are frequently used to simplify the control dynamics for robot hopping or running. Passive limit cycles can emerge for such systems and be exploited for energy-efficient control. A grand challenge in locomotion is trunk stabilization when the hip is offset from the center of mass (CoM). The swing phase plays a major role in this process due to the moment of inertia of the leg; however, many template models ignore the leg mass. In this work, the authors consider a robot hopper model (RHM) with a rigid trunk and leg plus a hip that is displaced from the CoM. It has been previously shown that no passive limit cycle exists for such a model given a linear hip spring. In this work, we show that passive limit cycles can be found when a nonlinear hip spring is used instead. To the authors' knowledge, this is the first time that a passive limit cycle has been found for this type of system.

The RoboKrill robot has appendages (right) that move like krill's swimming legs through water A robotic leg moving through water creates similar patterns to the motion of krill as they swim, and could be used to study the role these animals play in their marine environment. Krill are small crustaceans that serve as one of the most important and largest ocean food sources.

Day by day, human beings grow more and more inadequate. They can burn us in a foot race. And they can even read our damn minds. Now a little robot from the University of California Berkeley is putting on a jumping clinic. Meet Salto, the bot that not only leaps four times higher than its height--higher than you could ever manage--but strings together multiple jumps and bounds off walls in the process.

Disney's research division revealed last year that one of the company's goals is to bring its fictional characters to life... as robots. Well, folks, we may now be witnessing the birth of a robotic Tigger. The House of Mouse's scientists have designed a bouncy machine with one leg that can hop around without support. It can only stay upright for around 19 hops before it adorably topples over, but according to its creators, other one-legged robots and aren't as portable and can't balance on a single limb without a tether. Tigger-bot, however, can naturally bounce on its own. The secret lies in its leg mechanism that the researchers call "Linear Elastic Actuator in Parallel" or LEAP.