In this paper we present a human-oriented approach to the study of the biped gait for a humanoid robot. Starting from the analysis of the human lower-limbs, we figured out which features of the human legs are fundamental for a correct walking motion and can be adopted in the mechanical design of a humanoid robot. In particular we focus here on the knee, designed as a compliant human-like knee instead of a classical pin-joint. For the foot we tried to reproduce in a simple mechanical device the mobility and lightness of the human foot, which is very different from a flat surface and has a big impact on walking. We complete the presentation with considerations about the energy consumption of our humanoid design. In our approach the robot gains in adaptability and energetic efficiency, which are the most challenging issues for a biped robot.

This paper describes the design of a fast long-jumping robot conceived to move in unstructured environments through simple feed-forward control laws. Despite the apparent similarities with hopping, jumping dynamics is peculiar and involve non-trivial issues on actuation powering, energy saving and stability. The "Grillo" robot described here is a quadruped, 50-mm robot that weights about 15 grams and is suited for a long-jumping gait. Inspired by frog locomotion, a tiny motor load the springs connected to the hind limbs. At take-off, an escapement mechanism releases the loaded springs. This provides a peak power output that can exceed several times the maximum motor power. In this way, the actuation and energy systems can be significantly reduced in weight and size. On the other hand, passive dynamics is exploited by compliant forelegs, that let to partially recover the impact energy in their elastic recoil. Equipped with a 0.2W DC motor, the robot is dimensioned to achieve a forward speed of 1.5 m/s, which corresponds to about 30 body length per second.

This paper presents a bioinspired concept of locomotion for small autonomous robots. Scale effects in locomotion highly influence gait efficiency and in lightweight micro-robots jumping can be more energetically efficient than just walking or climbing. In addition, a jump can make the robot overcome obstacles and uneven terrains. Inspired by nature, the actuation of the proposed robot is entrusted to loaded springs. During the flight phase, energy from an electric micro-motor is collected in springs, while it is released by a click mechanism during take-off. In this way instant power delivered by rear legs (about 5 W) is much higher than the one provided by the motor (0.3 W). Passive compliant legs and low-power actuation result in light, efficient micro-robot, designed to have long autonomy for environment exploration and monitoring. In order to verify these assumptions, a quadruped prototype was developed, with two active rear limbs and passive elastic forelegs. Robot Grillo is 50 mm long and weighs about 10 grams. In conservative simulations the microrobot reaches a forward speed of 1.5 m/s, which corresponds to about 30 body length s-1