Posture Sensing Chair

In the era of computers and smartphones, people have adopted a sedentary lifestyle forcing themselves to sit for longer hours. While seated, people forget about their sitting posture and often complain about back pain. The adoption of a poor sitting posture over long periods can lead to back and neck pain which have a huge impact on the cost of work-related illness (occupational disease). Estimates show that only in the USA, 50 billion dollars are spent every year for the treatment of back pain. Moreover, in India maximum people have jobs in which they have to sit for long hours at the same place working on computers. It has been shown that on an average, people with sedentary jobs sit for 9.95 hours on working days and 8.07 hours when not working. It is noted that sitting for long hours at the same place harms the physical and mental health.

To combat this problem, I came up with an idea of creating a chair with sensors at correct places to detect the sitting position of a person. A lot of research papers have already been published on this and people have made such sensing chairs. A research was done by Jingyuan Cheng, Bo Zhou, Mathias Sundholm and Paul Lukowicz on a smart chair in which they installed pressure sensors and made an investigation on how much information can be extracted from simple pressure sensors mounted under the legs of a chair. They showed that it is possible to detect not only different postures but also subtle hand and head-related actions. For a correct sitting position, the weight of your thighs should be equally distributed, your lumbar region and the region above it should be in contact with the backrest.The body weight of the person should be equally distributed to the seat pad, backrest and armrest of the chair.

For this, the use of load cell was initiated but unfortunately had some issues and ended up with touch sensors and force sensor. So basically the idea was to place the touch sensors over the seat pad and arrange them in a regular pattern to detect the presence of thighs and buttocks. If any person sits with crossed legs or one leg lifted, that person would be alerted with a vibration motor. Also, a force sensor and two touch sensors were installed at the backrest. So, if anyone is slouching or leaning that would be detected and the person would be alerted. The use of a load cell would be much better as it would be easy to check for equal weight distribution. Instead of a load cell, force sensors can also be used to verify weight distribution.

As this was a group project, I and my college mate worked together and developed a prototype using MPR121 capacitive touch sensor, force-sensing resistor, vibration motor and Arduino UNO. Here is a picture of our model.

Well, it is not a perfect prototype, a lot of changes and modifications have to be done to get a perfect posture sensing chair. Also, these connections weren't tried on an actual chair. But here is a basic representation of the model.  

Hope you like it.