A ROBOT that combines the advantages of jointed legs and wheels to negotiate uneven ground has been developed by engineers at the Helsinki University of Technology, Finland. The WorkPartner surprised visitors at the Industrie 2004 exhibition in Paris, France, last month with its novel motion.
Designed for outdoor work, the buggy-like robot has four legs, each of which ends in a motorised wheel. Each leg is jointed at 鈥渉ip鈥� and 鈥渒nee鈥�, and the legs can move independently of each other. On even ground, the robot rolls forward on its motorised wheels. But when the ground becomes uneven or too loose for conventional wheels, the robot changes to a combination of walking and rolling.
In this mode, three of the legs stand still while the fourth extends forward, moved along the ground by both its wheel motor and its leg 鈥渕uscles鈥�. The wheel stays in contact with the surface and the leg continues to carry its share of the machine鈥檚 weight, so the robot remains stable. If there is an obstacle in the way, the wheel will travel up and over it. This leg then stands firm while the other three follow it in turn.
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The inventors have coined the verb 鈥渢o rolk鈥� to describe this hybrid rolling and walking motion, which enables the machine to cross loose surfaces, such as sand and snow, more quickly than walking. On an even surface, it can roll at 7 kilometres per hour, walk at more than 1 km/h 鈥� and rolk at almost 2 km/h.
鈥淣obody has really tested a legged robot safely at running speed because it鈥檚 a difficult software problem,鈥� says Aarne Halme of the university鈥檚 robotics institute. 鈥淪o we chose to develop our hybrid with legs and wheels.鈥�
Takeo Kanade, former director of the Robotics Institute at Carnegie Mellon University in Pittsburgh, Pennsylvania, says multiple locomotion modes will be deemed successful if they allow robots to travel as fast as walking humanoid robots: about 4 km/h.
The WorkPartner project began in 1998 and 卢1.6 million has been spent developing a generic prototype. The robot has been developed for many applications, including gardening, cleaning and carrying.
