Salto: Monopedal Jumping Robot
Salto is a small jumping robot with only one leg. Its design is inspired by the biomechanics of the lesser bushbaby (Galago senegalensis) — a squirrel-sized primate capable of leaping two meters from a stand-still. I developed mechanisms, controllers, and estimation strategies to bring the performance of robots like Salto closer to the inspiring behavior of animals.
Salto-1P Leaping and Landing (2020 Journal Paper)
Landing and stopping is a challenge for a robot with only one little foot. In collaboration with Roodra Singh and Roy Featherstone at the Istituto Italiano di Tecnologia, we developed balance control that enables Salto-1P to stick its landings like a gymnast. After landing, Salto can stand upright or power down. While standing upright, Salto-1P’s new balance control can even direct extra accurate leaps to hit narrow targets. This new launch is about 3-4 times more accurate than the previous flight-phase based precise hopping control from 2018.
Salto-1P Onboard Estimation (2019 Conference Paper)
To get out of the lab, Salto-1P must estimate its attitude and velocity using only its own onboard sensors and processor. This is challenging for hopping robots as they alternate between free-fall in flight and vigorous acceleration in stance. We developed the SLIP Hopping Orientation and Velocity Estimator (SHOVE) that uses Salto-1P’s onboard sensors to measure velocity, then uses velocity measurements to correct its attitude estimate. Running this algorithm on its onboard processor, Salto-1P can hop autonomously or follow human commands from a joystick.
Precise Hopping with Salto-1P (2018 Conference Paper)
Navigating a complicated environment like a forest or an office requires careful foot placement. A wrong step can send a small jumper careening off of a branch or desk. Using offline simulations, we developed a precise controller for Salto-1P to place the robot’s foot at particular locations (like playing one-legged hopscotch). With the new controller’s high precision, Salto-1P can leap up onto a chair and desk. We also investigated how foot placement precision degrades as Salto-1P’s jumps become more aggressive.
Bouncing Around with Salto-1P (2017 Conference Paper)
Jumping allows small locomotors to reach heights and cross gaps larger than their own size. With a reaction-wheel tail and two small propellers, the upgraded robot Salto-1P can control its angle in the air to direct its bounce and run around. Salto-1P is only 30 centimeters long (1 foot) but it can leap 1.25 meters (4′ 1″) in the air, long jump 2.2 meters (7′ 2″), and run 3.5 meters per second (7.8 mph). During its energetic bouncing, Salto-1P spends only 7.7% of its time on the ground.
Natural environments and human spaces alike contain many obstacles like cliffs or stairs that might impede a small robot. Inspired by Galago senegalensis, Salto (which stands for Saltatorial Locomotion on Terrain Obstacles) generates rapid high-power jumps to not only leap over obstacles, but use them to its advantage. With Salto’s high power, we demonstrated a novel wall-jump maneuver. By leaping at a vertical wall and propelling itself off of it, Salto can reach higher heights than it could reach in a single jump from the ground.