A small prototype mobile robot is capable of (1) hopping to move rapidly or avoid obstacles and then (2) moving relatively slowly and precisely on the ground by use of wheels in the manner of previously reported exploratory robots of the "rover" type. This robot is a descendant of a more primitive hopping robot described in "Minimally Actuated Hopping Robot" (NPO-20911), NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 50. There are many potential applications for robots with hopping and wheeled-locomotion (roving) capabilities in diverse fields of endeavor, including agriculture, search-and-rescue operations, general military operations, removal or safe detonation of land mines, inspection, law enforcement, and scientific exploration on Earth and remote planets.
The combination of hopping and roving enables this robot to move rapidly over very rugged terrain, to overcome obstacles several times its height, and then to position itself precisely next to a desired target. Before a long hop, the robot aims itself in the desired hopping azimuth and at a desired takeoff angle above horizontal. The robot approaches the target through a series of hops and short driving operations utilizing the steering wheels for precise positioning.
Features of this robot include the following:
- An adaptive controlled nonlinear spring mechanism capable of delivering force of specified intensity for hopping;
- Three deployable wheels. Two in front are independently controlled for driving and steering. The third is passive and is located in the rear of the vehicle;
- An autonomous mechanism for self-righting after landing from a hop (described in more detail below);
- A digital camera for acquiring image data;
- Electronic hardware for processing acquired data, computing hopping and roving trajectories, and either wired or wireless communication with a host computer;
- Software for use in sensor-based navigation, trajectory computations, and adjustment of hopping parameters.
The robot has a mass of about 1.5 kg and a minimum volume of about 30 cm3. It can jump about 1 m high and 2 m horizontally. After landing, the robot rights itself by a combination of actuation of side panels and shifting of its center of mass. The side panels also afford protection at landing and, in future versions, will carry photovoltaic panels for charging batteries.
Once in its upright position, the robot can sit still, move by use of its wheels, or prepare for another hop. The hopping distance can be adjusted by choosing an appropriate takeoff angle and controlling the spring loading. In the present version, images from the onboard camera are sent to a remote operator, who controls the operation of the robot; in future versions, the onboard software will enable autonomous navigation by the robot.
This work was done by Edward Barlow, Nevellie Marzwell, Sawyer Fuller, Paolo Fiorini, Andy Tretton, Joel Burdick, and Steve Schell of Caltech for NASA's Jet Propulsion Laboratory.