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Engineers Develop Chair With 'Sense'

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    NHNE News List Current Members: 387 Subscribe/unsubscribe/archive info at the bottom of this message. ... PURDUE ENGINEERS DEVELOP A CHAIR WITH SENSE Purdue
    Message 1 of 1 , Nov 2, 2000
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      Subscribe/unsubscribe/archive info at the bottom of this message.


      Purdue University /EurekAlert!
      Thursday, November 2, 2000


      WEST LAFAYETTE, Ind. ‹ Purdue University engineers have developed a "sensing
      chair" that can determine a person's sitting posture, research that could
      lead to numerous applications, from computer-security systems to the design
      of more comfortable furniture.

      The modified office chair uses software algorithms, or computer
      instructions, that interpret information collected by an array of pressure
      sensors in the backrest and seat. When tested on 30 people, the chair
      demonstrated an overall accuracy of 96 percent in determining whether people
      were slouching, leaning in various positions, crossing their legs or sitting

      "The chair senses how the pressure is distributed in the seat and the
      backrest," said Hong Tan, an assistant professor at Purdue's School of
      Electrical and Computer Engineering. "We train the computer to recognize
      pressure patterns associated with different seating postures by showing the
      computer examples of such patterns."

      Lynne A. Slivovsky, a doctoral student working with Tan, will present a
      research paper about the work Nov. 9 during the 2000 International
      Mechanical Engineering Congress & Exposition, sponsored by the American
      Society of Mechanical Engineers in Orlando, Fla.

      Special software enables a computer to interpret a person's posture by
      analyzing pressure patterns, which are represented by thousands of numbers
      fed to the computer by numerous sensing elements, or "sensels," in the
      chair. Each time a person sits in the chair, the computer creates precise
      "pressure maps" that can distinguish between different people, even if they
      are sitting in the same position.

      The system is limited in that it is capable only of sensing "static
      posture," or how a person is sitting at any one given time.

      "Currently, we are working on a dynamic system so that we can see how people
      are moving, throughout an eight-hour day, for example," Tan said.

      Such an advanced "real-time sitting posture tracking system" would lead to
      many applications. Because the system would be able to recognize the
      pressure patterns peculiar to specific people, a potential application might
      be to verify authorized personnel for computer-security purposes.

      A sensing chair also might be used in cars to automatically adjust the
      driver's seat according to who is behind the wheel, or to control an
      airbag's deployment by adjusting for a person's seating position and weight.

      Another potential application could be to improve the ergonomics of

      "People come into the showroom, they sit down, they think, 'Oh, this chair
      feels great,'" Tan said. "They buy it, and then they return it because after
      several hours of sitting in it, it doesn't feel great any more.

      "So, chair manufacturers are interested in how to evaluate a chair over an
      extended period of time. They want to understand the long-term dynamics of

      The chair is most adept at sensing when someone is slouching, correctly
      interpreting that posture with an accuracy of 99.8 percent.

      "For anybody who wants to do anything related to ergonomics, slouching is
      the one posture you probably really want to discourage," said Tan, who
      specializes in research focusing on the haptic human-machine interface, or
      how machines and people interact through the sense of touch.

      Perhaps such a sensing chair might sound a warning beep every time its user
      assumed a slouching posture, she said.

      Researchers said they were surprised the chair was able to accurately
      distinguish between the subtle posture differences of leaning left, crossing
      the right leg while leaning left or crossing the right leg without leaning
      at all.

      "We were expecting to see a lot of confusion among those three because they
      are so similar," Tan said.


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