1. The working principle of the smart bracelet
1. The principle of the smart bracelet for step counting
The smart bracelet The motion monitoring function is realized by the gravitational acceleration sensor. Gravity sensor is a very mature technology, and mobile phones have long been used. For example, the screen flip function of smart phones is now realized through sensors. The sensor obtains some basic data by judging the movement of the person, and then combines the basic information of the personal physical signs entered by the user before, and obtains personalized monitoring data for the individual according to some specific algorithms, such as the number of exercise steps, distance and calories consumed, etc. , so as to determine the frequency and intensity of exercise. Since each person’s movement has different effects with different personal physical signs, users need to enter their gender, age, height, weight and other information in the APP before using the bracelet for monitoring, and the information is automatically synchronized to the bracelet. The sensor monitors the motion, and finally realizes the function of motion monitoring through a specific algorithm.
2. How does the smart bracelet monitor sleep
Sleep monitoring is also achieved through the same sensor technology. Human sleep can be divided into five stages according to brain wave signals: falling asleep, light sleep, deep sleep, deep sleep, and rapid eye movement (REM). Human brain waves can change rapidly at different stages. Interestingly, the gravitational acceleration sensor does not have the function of directly detecting brain waves, so it uses the amplitude and frequency of people’s actions during sleep as the standard to measure sleep. Which stage of sleep is in, the smart alarm clock function of the bracelet will wake up the user during the rapid eye movement period, “because during the rapid eye movement period sleepers will have high-frequency and low-amplitude brain waves similar to those when they are awake, and it is easier to wake up. If you wake up at this time, the sleeper will feel refreshed and have a good sleep effect.”
3. Principle of smart bracelet heart rate monitoring
Using a reflective photoelectric sensor, by passing the incident light through the skin into the deep tissue, except being absorbed by the skin, muscles, blood, etc., the remaining part of the light transmission is sensed by the photosensitive receiver, and by measuring the blood volume in the blood vessel with the Changes in heart pumping and periodic changes in blood volume constitute the basis for all heart rate estimation using PPG signals. Heart rate estimation is achieved by calculating the distance between feature points (such as peaks) in adjacent cycles.
