A robotic mountaineer that could one day climb cliffs on Mars and even help rescue earthquake victims has taken its first steps.
The spider-like robot, called Lemur, was developed by engineers at Stanford University and NASA鈥檚 Jet Propulsion Laboratory (JPL) in California, as a prototype for a fully autonomous rock climber. It can already follow a human climber up an irregular surface without any guidance from a controller. And it has a spookily human gait.
JPL is better known for its twin Mars rovers, Spirit and Opportunity, which have been roaming the Red Planet since January. The rovers have transmitted images of the planet鈥檚 surface and gleaned much information from soil and rock samples.
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But Tim Bretl, the lead engineer on the project at Stanford鈥檚 robotics laboratory, says Lemur鈥檚 technology could take planetary exploration to another level. 鈥淪cientists would really like robots on Mars to be able to access the sides of cliffs to look at the geology,鈥� he says. 鈥淭his could be a way to get there.鈥� He will reveal the technology next week at a symposium on experimental robotics in Singapore.
Bretl also reckons that climbing robots could have search and rescue applications on Earth. 鈥淎 lot of people are becoming interested in using robots for disaster scenarios, like earthquakes,鈥� says Gurvinder Virk, a robotics expert at the University of Leeds in the UK.
Triple joints
While other climbing robots are designed to scale the sides of flat structures using suction cups or magnets for grip, tackling uneven geological surfaces is a far more difficult task. With a central body and four triple-jointed limbs, Lemur鈥檚 gait resembles that of a human rock climber as it manoeuvres up an indoor climbing wall at Stanford (see graphic above, and videos ).
At the moment, the robot cannot stick to a sheer wall. But on uneven surfaces it can use the claw at the end of each limb to hook into a foothold. 鈥淚t鈥檚 like a human climber using a single finger,鈥� Bretl says.
For the moment Lemur cannot 鈥渟ee鈥� its footholds, so a computer model of the wall, containing coordinates of the footholds, has to be fed into its onboard computer before it starts climbing. From this it figures out an ideal route up and works out how to manoeuvre itself for each step of the ascent.
The ultimate goal is for Lemur to read a scene and calculate its own best path up a cliff. The route would be modified as it climbed, using information from its own video cameras and touch sensors. At the moment, the sensors are used only to make sure that each foothold is secure.
Weight shift
After Lemur moves one of its limbs to a new foothold, it must simultaneously shift its weight by repositioning the other three limbs to maintain balance. This requires complex on-the-fly calculations from its onboard computer.
Route-planning software specially developed for the task rapidly analyses different limb configurations before settling on the most efficient one for the next step.
It can take the robot a few minutes to work this out, although a forthcoming redesign of the control system should speed it up, allowing the robot to 鈥渟camper鈥�.
Future incarnations of Lemur are likely to have grippers for a more secure foothold, and more joints in the articulated limbs, giving them a greater range of movement. It will also be taught how to react if it unexpectedly loses its grip.