November 30, 2012      

Many of today’s robots are like pre-technology-era human explorers: sent out on missions with no real knowledge of the local landscape and without the help of detailed maps or directions.

Addressing this challenge, engineers at Germany’s Fraunhofer Institute for Optronics, System Technologies and Image Exploitation (OSTIE) have developed a mobile robot platform that can autonomously reconnoiter and map uncharted terrains. The system relies on an internal computer containing special algorithms, as well as data drawn from multiple sensors, to help it negotiate and remember trails blazed through unknown territories.

There’s a steadily increasing need for nimble mobile robots that are independent of human control. Such machines are now routinely used to explore a variety of dangerous environments, including mines, collapsed buildings, hazardous material sites and hostage settings. Yet such robots’ human controllers are often as clueless to the local terrain as the robot itself. “It’s far from a perfect situation,” says Christian Frey, a Fraunhofer OSTIE engineer who helped create the new robot.

A Fresh Approach

Frey says that the new platform, as yet unnamed, required its developers to rethink the way robots deal with the world surrounding them. “To be able to navigate on its own, autonomously, a mobile robot must meet several different requirements,” Frey says. “It has to be able to localize itself within its immediate surroundings as well as continuously recalculate its position as it moves through hazardous places, plus it also must simultaneously refine the map it is generating along the way.”

Creating and following maps on-the-go is as challenging a mission for robots as it is for human explorers. But the Fraunhofer OSTIE system can take advantage of powerful tools that aren’t typically to people, such as a flawless memory, a highly resilient exterior and sensors specifically designed for exploring virtually any type of terrestrial environment. The platform’s odometry sensors, for instance, measure wheel revolutions, allowing the robot to precisely judge distances. Inertial sensors, meanwhile, calculate accelerations to improve distance accuracy while obstacle detection sensors monitor the robot’s exact distance from walls, steps, ledges, furniture, trees and other obstructions and dangers.

As the robot rolls along, cameras and laser scanners augment the mapping process by detecting and recording the local environment. Algorithms created by Fraunhofer OSTIE engineers interpret the sensors’ data to fix the robot’s exact location. The entire Simultaneous Localization and Mapping (SLAM) process results in a digital map that’s updated continuously and accurately, the researchers say.

Fraunhofer OSTIE engineers also strived to design mobile robot technology that could find the optimal path to a particular destination, either the shortest and quickest route or the one that is the most energy efficient. The designers also needed to develop rules for mobility restrictions, such as the robot’s turning radius as well as its ability navigate around obstacles. Another important factor was giving the robot the power to make on-the-spot route changes mandated by environmental changes, such as when debris dislodged by an earthquake aftershock suddenly renders a previously recorded path unusable.

Adaptable and Flexible

Fraunhofer OSTIE wants to make its technology available to robot manufacturers offering producing virtually any type of mobile robot. Frey says the developers worked hard to build flexibility into their system. “Our algorithm toolbox, for example, was developed from the outset to fully modular,” he says. “Users shouldn’t have any trouble adapting the supplied algorithms to work with different kinds of mobile robots operating in indoor or outdoor applications.”

Frey says that the platform can accommodate virtually any type of sensor configuration or robot wheel drive arrangement. The software, meanwhile can be customized to satisfy the needs of specific manufacturers. “It is adaptable for all sorts of applications?emergency response scenarios, building patrols, pipeline inspections and so on,” Frey says. “It can even be installed in cleaning robots or lawnmowers.”