I’VE FALLEN AND I CAN’T GET UP
it because he valued the robot so much. When Kessens heard about this Soldier’s experience, he immediately wanted to solve the problem.
“My role,” Kessens said, “is to do robotic manipulation research that will positively impact future Army operations.” He and the rest of ARL’s Autonomous Systems Division’s advanced mobility and manip- ulation team want to understand how robots can right themselves so that the future Soldier has semi- or fully autono- mous robots on the battlefield.
MOTION CAPTURE
ARL’s Autonomous Systems Division captures robotic movement using cameras like this one mounted on a large steel frame. The test robot is outfitted with motion capture markers that the camera system locates in the near-infrared spectrum to find joints and record dynamics of the robot.
BOT FLIPPING 101 Te problem, as Kessens sees it, is that today’s robots are unable to reorient them- selves after experiencing a disorienting event, like falling into a ditch or being knocked over. Te solution, then, is to give robots the ability to self-right. To do that, the robots need to be more aware of the space they are in and how they can move in that space. Kessens has developed a two-part software package, referred to as self-righting software, to give the robots that ability. Te first part of the software is for analyzing the robot’s structure, while the second part is for planning and execut- ing self-righting maneuvers.
ROBOT MARKERS
ARL research scientists use these reflective globes—motion capture markers—in conjunction with motion capture cameras to find joints and record the dynamics of a robot. The markers come in several sizes and can be attached to the test robot in hundreds of configurations.
“My job as an Army researcher is to really understand the entire problem,” Kessens said. His main goal is to understand the robot’s morphology using the analyt- ical part of the self-righting software. Morphology is the study of the forms of things; in this instance, Kessens is study- ing the robot’s shape, where its joints are and how they are oriented in relation to one another, how heavy the limbs are relative to one another, and all the other different parameters that go into the phys- ical makeup of a robot. “How does [the morphology] affect its ability to self-right, and under what circumstances can it not self-right?”
50 Army AL&T Magazine Spring 2019
Te goal of the software is to encompass as many varieties of robotic systems as possible; therefore, the research has to be relatively generic. However, all research has to start with a set of control parame- ters: Kessens and the research team assume that the software will be used for robots with rigid bodies, and that have sensors that can determine what configuration the robots are in and in what direction gravity is acting, Kessens said. “So we need something, a sensor like an IMU— inertial measurement unit—or we could use just accelerometers or inclinometers. Tere are different ways to get that infor- mation,” he said.
An IMU is the sensor in a smartphone that changes the screen from vertical to horizontal, and vice versa, when the phone is turned sideways—what happens when you flip your phone to look at a photo, for instance. IMUs “are relatively cheap and pretty ubiquitous, so it’s not a leap to assume that a robot would have such a sensor,” Kessens said. Te team is also considering the size of the robot in its analysis. Larger robots tend to have more computing power, but robots that could fit
The self-righting software is relevant to the development of the Next Generation
Combat Vehicle—some of these vehicles will be optionally manned or fully autonomous in the future.
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