Design Of Body Pressure Discribution Measurement System For Sitting Posture

Sitting occupies a large part of people's lifetime. However, a long-term sitting may cause tumefaction and lumbar disease such as vertebral trauma or intervertebral disc for partial over weight or unbalance pressure putting on body. The research indicates that abnormality sitting posture may induce many diseases, especially for those who had bedsore or hemiplegia; the diseases may be deadly in some case. Body pressure distribution means the pressure the body suffered and its distribution when you sitting. So it is significant to measure body pressure distribution, especially for the pressure of arthrosis suffered. Body pressure measurement system is an effective means to prevent above diseases. Unfortunately, the internal existing research in pressure measurement system focuses on thenar pressure distribution seldom pays attention to body pressure distribution.Body pressure distribution deeply relates to sitting posture, and the body pressure measurement system could successfully measure pressure distribution and analyse sitting posture. It can guide people to sit in a proper posture, and be helpful to prevent pressure sore.The body pressure measurement system comprises four parts: pressure sensor array, multi-signal switch circuit, signal collection and interface circuit, and computer images process software.The pressure sensor array is composed of superstratum, substrate and many sense organs. The electric rubber are applied as sensor units, using its pressure-resistance characteristic and applying special layered structure and manufacture, the pressure sensor array is designed.According to the characteristic of multiple signals of the system, analog multiplexers are applied to switch the signal as A/D convertor's input. To decrease the effect of the leak current, the analog multiplexers are designed to be two stages.In the signal collection circuit, a 12-bits MAX174A A/D converter is employed. And the communication between PC and the system is via RS232 serial interface.The computer images process system contains a real-time sample model, a display model and an analysis model. According to the pressure-resistance linear equation, the computer images process system transformed the received voltage data into pressure data correspondingly, and then displays it as a chromatogram. To get a better vision effect, the color setting of the chromatogram follows the characteristics of human eyes in distinguishes colors. And at last, map the distribution image by using nearest neighbor interpolation and bilinear interpolation arithmetic and display it.Finally, Body pressure was measured through the system in 1 normal individual and 3 who had trauma in lumbar. Using this system can implement a dynamic, real time measurement for the distribution of pressure between the body and chair. The comparison of the results is distinct and reasonable.The results indicate that the scheme of the system is reasonable and feasible.moreover, the design makes a solid foundation for the further study.