MIT researchers who previously built a robotic cheetah have now trained it to automatically detect and leap over multiple objects while it runs. The scientists claim it's the first four-legged robot to be able to do so. To get a running jump, the robot plans out its path, much like a human runner: As it detects an approaching obstacle, it estimates that object’s height and distance. The robot then gauges the best position from which to jump, and adjusts its stride to land just short of the obstacle, before exerting enough force to push up and over.
Last September, Sangbae Kim, an assistant professor of mechanical engineering at MIT and his colleagues demonstrated that their robotic cheetah was able to run untethered— a feat that Kim notes the robot performed “blind,” without the use of cameras or other vision systems.
Now, the robot can “see,” with the use of onboard LIDAR — a visual system that uses reflections from a laser to map terrain. The team developed a three-part algorithm to plan out the robot’s path, based on LIDAR data. Both the vision and path-planning system are onboard the robot, giving it complete autonomous control.
The algorithm’s first component enables the robot to detect an obstacle and estimate its size and distance. The researchers devised a formula to simplify a visual scene, representing the ground as a straight line, and any obstacles as deviations from that line. With this formula, the robot can estimate an obstacle’s height and distance.
Once the robot has detected an obstacle, the second component of the algorithm kicks in, allowing the robot to adjust its approach while nearing the obstacle. Based on the obstacle’s distance, the algorithm predicts the best position from which to jump in order to safely clear it, then backtracks from there to space out the robot’s remaining strides, speeding up or slowing down in order to reach the optimal jumping-off point.
In experiments on a treadmill and an indoor track, the cheetah robot successfully cleared obstacles up to 18 inches high — more than half of the robot’s own height — while maintaining an average running speed of 5 miles per hour.
The MIT scientists next plan to demonstrate their cheetah’s running jump at the DARPA Robotics Challenge in June, and will present a paper detailing the autonomous system in July at the conference “Robotics: Science and Systems”.