Heart Rate Detection Based On Photoplethysmographic Imaging

In the contemporary society, cardiovascular disease has became one of commondisease which threatening our health. In order to control the incidence of thesediseases requires long-term monitoring of the patient’s cardiovascular physiologicalinformation.The volume pulse blood flow which contains abundant messages ofcardiovascular physiology. Photo-Plethysmography is a kind of wave signal by meansof photoelectric detecting blood volume in living tissue. But in traditional methods, itoperating complex and will bring inconvenience and discomfortable. This requires asimple measuring method——Photo-Plethysmography imaging.So called PPGI, acamera as the sensor of Photo-Plethysmography and get vital signs information bycertain technical processing.This design using SOPC embedded technology hardware and softwarecollaborative design based on xilinx fpga.The design mainly includes three parts:(1) PPG signal collection: This part is to capture the finger skin surface image byCMOS camera, then get RGB color image formats after image processing. In eachframe the R, G, B three channels pixels occurred is calculated, plotting the pixel valueof each frame against the time yields PPG signal will be got.(2) PPG signal processing and analysis of the factors that affect the PPGsignal:The part is convey text to PC, using MATLAB to reduce noise after filteringprocessing, and analysis the influence of PPG signals about illumination, Motionartifact and low perfusion index.(3) Two rate calculation methods: The third part introduces the time andfrequency domain of two kinds of heart rate calculation methods. Detecting the peakson time domain in the certain time and using FFT spectrum analysis on frequencydomain to calculate the heart rate. Finally heart rate detection is proved feasibilitywhether in MATLAB or FPGA from finger image.In this paper, based on PPGi heart rate detection technology is a low-cost,non-contact method, relative to the widely used in intelligent mobile phone apps heartrate detection, outstanding advantage is no need for the LED emission source, it canbe directly used in ordinary light environment. Due to the volume pulse blood contained in heart beat, blood flow, and many other cardiovascular system importantphysiological information, so the technology can be used not only in terms of heartrate detection but also detect like heart rate variability and blood pressure, respirationrate and other physiological characteristic information, thus PPGi technology innoninvasive detection of physical characteristics information has a broaddevelopment space and a wide range of applications.