The Buzz About Haptics

Kristy Stokke's long blond hair floats haphazardly and her feet slowly slide above her head. The Massachusetts Institute of Technology senior is struggling to conduct an experiment in zero-G conditions.

But Stokke is far away from MIT's campus labs. Far above them, too, for that matter. She's working in NASA's KC–135 microgravity research aircraft, officially named Weightless Wonder but better known as "The Vomit Comet." High above the Gulf of Mexico, the pilots of the four-engine jet follow a precise parabolic flight path, making a series of 45-degree climbs and descents that alternately subject the aircraft, its passengers, and their equipment to zero and positive 2 Gs.

Stokke is too busy to think about motion sickness, a condition to which many of her fellow student researchers have succumbed. Instead, she's focused on her search for the answer to one question: Are there haptics in your future?

An enthusiastic private pilot, Stokke sought to combine her interest in general aviation with the thesis that she had to complete as part of her undergraduate degree in mechanical engineering. Concerned about how easily VFR pilots can become disoriented when visual references are diminished, she hypothesized that disorientation can be reduced—and flight safety increased—by replacing the missing sensory cues. The result was Aeronautical Orientation Research Through Haptics—a Study of Tactile Attitude Recovery, dubbed Northstar. Haptics means tactile, or relating to the sense of touch. In the experiment, small vibrating tactors attached to a belt worn around the torso of a pilot would vibrate to indicate unusual pitch and roll attitudes of the airplane. The tactile feedback system relays the same information as an attitude indicator, only through touch instead of sight. For example, if the aircraft is turning right, a tactor on the pilot's right side buzzes to indicate the right turn; if the plane is descending, a vibration in the pilot's abdomen indicates that the nose is below the horizon.

Stokke learned that the Navy had done some research on tactile feedback for flying—in large part, she says, because the Department of Defense attributes $300 million in aircraft losses annually to pilot disorientation. The Navy had trained a pilot to fly precise maneuvers using a tactile vest, outfitted with dozens of vibrating tactors, as the only form of sensory input, she explained. In addition, two MIT graduate students were working with tactile feedback as a means of navigating the international space station, and a team from Purdue University had done microgravity research on the perception of touch. But none of these efforts focused on general aviation.

With a project in mind she began to assemble a team. She met Tim Graves, a Texas A&M University student, when they worked together in a NASA cooperative education program. Dana Forti was a student in MIT's aeronautics and astronautics program. Jen Law wanted to participate in the project but couldn't miss two weeks of school for NASA-required training culminating in two microgravity flight opportunities, so she became the ground crew. Stokke still needed a computer programmer, so she e-mailed a plea for volunteers to students in a computer science and electrical engineering course—and the response was so great that she had to interview candidates before selecting John Thomas.

Meanwhile, a proposal for the zero-G flights had to be submitted to the Texas Space Grant Consortium, which administers the collegiate microgravity flight research program for NASA. (A similar program exists for high-school students.) Experiments are evaluated on scientific merit, feasibility of the design, the test plan, compliance with NASA experiment safety protocols, and the team's education and outreach plan. Meeting once a week, the Northstar team began working on its hardware in October 1999. In January, which is an independent activities period for MIT students, the team met daily. On January 14 the team received NASA approval to fly in the KC–135.

In late February, the team flew to Houston and spent more than a week at Ellington Field near NASA's Johnson Space Center for final experiment reviews, physiological training, and other preparations for zero-G flight. "The [altitude] chamber training was incredible," Stokke says. "All of a sudden you get to feeling a little drunk, and really happy"—then she forgot what happened. Afterward, she watched a videotape of the experience. "It was so funny to watch that video afterwards. I couldn't do math problems and couldn't write what NASA stood for. By the end I couldn't even write my name."

Day of reckoning

The night before their first flight, the team is huddled around equipment in the kitchen of their hotel suite. Computers and test equipment litter the counters, and wires are draped over the corner of a framed print hanging from the wall. Velcro scraps and soda bottles clutter the floor and the smell of solder hangs in the air. Team members made so many visits to a local electronic-component store that they are on a first-name basis with its staff.

There are problems with "the box," which holds the electronics that make the experiment possible. Shorts were causing components to fail so often that the box became known as "Pandora's box." Adding fuses slowed the replacement of components—instead, blown fuses were simply replaced. "I think I'm breathing in more solder than air," Graves remarks while Stokke searches for a roll of electrical tape.

Thomas skips dinner to continue refining the software. It's not the first activity a team member skips. Everyone attended all of the NASA-required training sessions, but because of unanticipated work, they missed several tours, talks by astronauts, and other events.

Late in the evening, team members begin drifting off to sleep. Forti is practicing with a yo-yo, which she'll use in zero-G conditions to illustrate the effect of weightlessness; her efforts will be videotaped for the educational presentations the team must make after its flight. But this, too, isn't going as well as desired. "Dana, it looks like you're going to be up for a while," a teammate quips.

The next morning kicks off with a preflight briefing for Forti and Thomas, who will make the first flight. Motion-sickness pills are distributed along with a copious quantity of airsickness bags; the students are instructed to remove several of the plastic bags from their paper envelopes, ensure that they have no leaks, and place them in accessible front pockets of their NASA-issued flight suits. "Is it possible to be too tired to throw up?" asks Thomas, who was up all night programming the software.

Eventually the briefings end. After the obligatory photographs, the researchers board the aircraft and the KC–135 taxies across the foggy airport for departure.

Houston, we have a problem

After takeoff, the groundbound team members make their way into a NASA hangar, where they can watch a live video feed from the airplane. A NASA Lockheed U–2 research plane is being overhauled nearby, but most eyes appear riveted to the television monitors as students try to comprehend the zero-G experience—the majority of those on the ground will fly the next day. Gravity reaches zero at the top of each parabola, for about 25 seconds. The aircraft crew's "Feet down!" warning call, which marks the transition from zero to positive 2 Gs, is heard loud and clear through the monitors. The 1.5-hour flight will include only 30 zero-G parabolas, so the student researchers must work fast.

As the flight progresses, more students clutching airsickness bags are escorted to the seating area in the rear of the airplane. "Ooh—was that Dana?" a concerned Stokke asks at one point.

Eventually the airplane levels, the video feed drops, and the team drifts outside to await the initial results. Forti and Thomas give a thumbs-up as they emerge from the airplane. On the ground, it's high-fives all around—neither of them got sick. "This is quite possibly the coolest thing I've done in my life," Thomas says of his zero-G experience.

But the experiment has not gone so well. The cables to the vibrating tensors pulled out of the electronics box, and Thomas had to open the box in flight. He thought that opening the box might have caused a failure. Bottom line, no data is recorded for Stokke's experiment. "It means we've got to work like crazy tomorrow," she says.

Recovery

"Two of our team members had just experienced microgravity, and the last thing they wanted to do was lock themselves back up in the hotel to pore over the hardware that had been haunting us for months," Stokke explains. "We had a quick celebration and managed to get back to the task at hand." They decide to radically streamline the experiment and make the hardware as simple as possible. This time, none of the preparation is left for the airplane. "We had left some initial setup for the first flight day, which proved more difficult than we imagined—in microgravity, even the simplest tasks pose some challenge."

After another late night, she and Graves are ready to fly the next morning. "Tim and I were both really excited about the flight, but we really wanted to make sure that we got good data—it was our last chance," she says.

On the first parabola, Stokke is acutely aware of all of her senses. "I didn't know what to expect. I remember rising up off the floor and feeling really strange—like a fish out of water. My first instinct was that I was going to fall—I had to reach out and grab something. [The experience] lived up to its reputation for being disorienting."

The zero-to-2-G transition slams passengers to the deck. "You feel like this huge person is sitting on top of you, crushing your chest and your face," Stokke says. "I wish it could be the other way around, with the zero G lasting twice as long as the 2 G."

More important, the equipment is working. The team collects good data—and then Graves becomes ill. He recovers for a few minutes and is able to resume the experiment. Stokke is fine, and because she is a pilot, is invited to sit in the KC–135's jump seat for landing.

"On landing, everybody was all smiles—from ear to ear. It was group euphoria. It's an experience that not many people can share," she says. "It's almost like the pilot camaraderie—once you've had your solo flight, you're a part of this group of people.

"I was pleased that we took data. If everything had gone like I'd hoped, we would have taken four times more data. But the euphoria of the flight made up for it."

Results

In the end, Stokke couldn't determine whether haptics will be in general aviation pilots' futures. "Because of the limited number of data points that we got on the flight, you could only use this data as a marker," or as a rough indicator. "We'd have to take a lot more data points in flight—or in some other disorienting situation—to say so conclusively." The bigger learning experience for Stokke was learning how to design a flight test and organize an experiment of this magnitude.

It was a good real-world experience, says Peter Young, a senior lecturer in aeronautics and astronautics at MIT, Stokke's thesis adviser, and adviser to the Northstar team. "In this case they did it well. Even when things were not looking very good, they held together. They were extraordinary." A retired Air Force colonel, Young experienced microgravity in the KC–135 during the 1980s. "I realized the benefits that could come to the students from the zero-G program—not just the flying, but the planning."

Stokke still believes that the technology could have applications for general aviation, but further validation is required—and some members of the Northstar team are thinking about continuing the project next year.

She thinks that the key to success would be to make a system that was intuitive and very unobtrusive. "It would be best if the system could be incorporated within the aircraft, maybe in the seat belt and seat back. If it's built into the plane you also remove the ego factor from using a safety device." She said the system also could have applications in remotely piloted vehicles and in spacecraft.

Despite the research setbacks, Stokke did obtain enough data to validate her hypothesis and complete her thesis. "Even though it was my thesis, it took all the members of the team working together to do it," she says, adding that the NASA crew at Ellington was super. "They treat the students like world-class researchers. It's a really incredible program that gets people psyched about flight research."

Stokke graduated from MIT in June with a bachelor's degree and is participating in the NASA Academy at Dryden Flight Research Center until mid-August. Then she will enter graduate school at Princeton University in New Jersey to study plasma physics as it is applicable to space propulsion.

She plans to continue her GA activities as well. Stokke has already found a flying club at Princeton that she's interested in joining, and when her finances permit, she'd like to pursue an instrument rating. "Someday I'd like to be a CFI," she says.

Links to additional information about NASA's research opportunities for students may be found on AOPA Online ( www.aopa.org/pilot/links/links0008.shtml). E-mail the author at [email protected].