National Geographic : 2011 Aug
only within rigidly structured environments. To negotiate human spaces, robots like HERB need to perceive and cope with unfamiliar objects and move about without bumping into people who are themselves in motion. HERB's perception system consists of a video camera and a laser navigation device mounted on a boom above his mechanical arm. ("We tend to think of HERB as a he," Srinivasa says. "Maybe because most but- lers are. And he's kind of beefy.") In contrast to a hydraulic industrial robotic armature, HERB's arm is animated by a pressure-sensing system of cables akin to human tendons: a necessity if one wants a robot capable of supporting an elderly widow on her way to the bathroom without cata- pulting her through the door. In the lab one of Srinivasa's students taps a button, issuing a command to pick up a juice box sitting on a nearby table. HERB's laser spins, cre- ating a 3-D grid mapping the location of nearby people and objects, and the camera locks on a likely candidate for the target juice box. e ro- bot slowly reaches over and takes hold of the box, keeping it upright. On command, he gently puts it down. To the uninitiated, the accomplishment might seem underwhelming. "When I showed it to my mom," Srinivasa says, "she couldn't un- derstand why HERB has to think so hard to pick up a cup." e problem is not with HERB but with the precedents that have been set for him. Picking up a drink is dead simple for people, whose brains have evolved over millions of years to coordinate exactly such tasks. It's also a snap for an industrial robot programmed for that speci c action. e di erence between a social robot like HERB and a conventional factory bot is that he knows that the object is a juice box and not a teacup or a glass of milk, which he would have to handle di erently. How he understands this involves a great deal of mathematics and computer science, but it boils down to "taking in information and processing it intelligently in the context of everything he already knows about what his world looks like," Srinivasa explains. When HERB is introduced to a new object, previously learned rules inform the movement of his pressure-sensitive arm and hand. Does the object have a handle? Can it break or spill? Srinivasa programmed HERB's grips by studying how humans behave. In a bar, for instance, he watched bartenders use a counterintuitive un- derhanded maneuver to grab and pour from a bottle. He reduced the motion to an algorithm, and now HERB has it in his repertoire. Of course the world HERB is beginning to master is a controlled laboratory environment. Programming him to function in real human spaces will be frightfully more challenging. HERB has a digital bicycle horn that he honks to let people know he's getting near them; if a room is busy and crowded, he takes the safest course of action and simply stands there, honk- ing at everybody. is strategy works in the lab but would not go over well in an o ce. Humans can draw on a vast unconscious vocabulary of movements--- we know how to politely move around someone in our path, how to sense when we're invading someone's personal space. Studies at Carnegie Mellon and elsewhere have shown that people expect social robots to follow the same rules. We get uncomfortable when they don't or when they make stupid mistakes. Snackbot, another mobile robot under development at Carnegie Mellon, takes orders and delivers snacks to people at the School of Computer Science. Sometimes it annoyingly brings the wrong snack or gives the wrong change. People are more forgiving if the robot warns them rst that it might make errors or apologizes when it screws up. en there are the vagaries of human nature to cope with. "Sometimes people steal snacks from the robot," says one of Snackbot's developers. "We got it on video." Like many social robots, Snackbot is a cute fellow---four and a half feet tall, with a head and cartoonish features that suggest, barely, a Chris Carroll covers the Pentagon for Stars and Stripes and has written frequently for National Geographic. Max Aguilera-Hellweg is drawn to stories at the intersection of science and humanity.