While vibrating chairs are usually meant for relaxation, a new chair designed by Yale engineers has a more corrective intention: using vibrations to fix posture.

Researchers in School of Engineering and Applied Science professor John Morrell’s laboratory have developed the Vibrotactile Posture Feedback Chair, which uses cell phone vibrators to alert a person when he or she is sitting incorrectly. The chair — which was showcased at the Institute of Electrical and Electronics Engineers’ Haptics Symposium in Waltham, Mass., on Mar. 25 — is far from being sold commercially, but Morrell said he hopes people accustomed to slouching at their computers will eventually have an inexpensive method to correct their bad habit.

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Morrell and Ying Zheng GRD ’14 retrofitted the popular plastic Herman Miller Aeron chair with six force-sensitive resistors, or tactors, and one distance sensor.

The tactors, which provide feedback by vibrating when a person deviates from a correct sitting position, were placed in the lumbar region of the back, two in the shoulder region, one in the lower back region and one underneath each leg.

“The vibration is supposed to be an annoyance,” Zheng said. “If I sit in the incorrect posture, at least one of the tactors vibrates.”

A box on the back of the chair transfers sensor measurements to a tethered computer, which processes the measurements to determine which tactors need to vibrate, Zheng said. When a person slouches, the tactor in the lumbar vibrates. When a person leans back, the two tactors in the shoulder region vibrate. When a person leans too forward, the whole back pulsates. When a person crosses his or her legs, lifts a leg or leans to one side, the tactors under the legs pulsate.

Morrell said he was first inspired to pursue this project in 2008 after visiting a physical therapist due to pain from sitting at a computer for long periods of time. He said he was constantly forgetting the instructions of his physical therapist, which led him and Zheng to evaluate how they could use the sense of touch to remind people to sit upright with their spines in a neutral position, as recommended by the National Institute for Occupational Safety and Health.

“I was still going back into slouching postures [after going to the therapist],” Morrell said. “I thought, ‘Wouldn’t it be nice if I could have a little more feedback?’”

While each chair must be calibrated to fit a person’s body structure, the hardware only costs $70, although the Aeron chair Morrell and Zheng modified has a market value of $1,000. They said they ultimately want to make the hardware inexpensive and simple enough that it can be used on any chair, Morrell said.

Morrell added that the chair was very popular when they demonstrated it at the symposium.

“Everyone wanted to come by and try,” he said.

Morrell’s laboratory is working to convert the sensor system so that it is attached to a small microprocessor board rather than a computer. Zheng said they will need to collaborate with medical professionals and a company interested in producing the chair before they can market the product.

In addition to the chair, Morrell’s laboratory is developing a robot that can open doors for the disabled or in dangerous situations.

Postdoctoral researcher Arthur McClung said the chair and the robot represent the goal of Morrell’s laboratory “to make machines compliant to humans.”

Morrell and Zheng’s paper on the chair was nominated for an award for the best student research paper at the symposium.

Correction: April 8, 2010

An earlier version of this article incorrectly stated that Yale researchers John Morrell and Ying Zheng’s paper on their chair won the award for the best student research paper at the Institute of Electrical and Electronics Engineers’ Haptics Symposium. In fact, the paper was nominated for the award.