1. The motion state of the mobile phone owner must be fed back to the mobile phone through the sensor inside the mobile phone. Motion information sensors are generally nothing more than gyroscopes (acquiring angular velocity), acceleration sensors (acquiring acceleration), barometers (acquiring height), magnetometers and so on. With the rapid development of microelectronics technology, these sensors can be directly integrated into a chip the size of a fingernail. For example, the common mpu6050 integrates a gyroscope and an accelerometer, and the mpu series integrated chips are used in general mobile phones.
2. As far as I know, some mobile phones hand over the task of processing these sensor data to the coprocessor, which can be regarded as a process of assisting the cpu. Because the current co-processing power consumption can be very low, it can always work and complete common motion statistics functions in the background, such as step counting. Let's talk about it. How can a mobile phone tell whether you are dumping your mobile phone or really leaving again?
In fact, what the sensor sends to the processor is some data of the motion direction. By comparing the collected data with the real walking data, if the characteristics of an action conform to the characteristics of walking, it is judged as walking. Some mobile phones can also distinguish whether they are pretending to walk or really walking by whether there is gps displacement. The algorithm of these judgments may be different for each company, but the final judgment effect is similar.
There are also multiple stairs in the phone to get height data. This is a typical barometer application. If you take the elevator up, although the height has changed but there is no movement, it is not climbing stairs. This is the subtlety of the algorithm.
3. Now, Apple's iOS 10 has added a new mobile phone wake-up operation, that is, picking up the mobile phone to automatically light up and putting it down to automatically lock it. These can also be recognized by this sensor. For example, when picking up a mobile phone, there must be an acceleration or speed towards the mobile phone. By analyzing the data of ordinary people operating mobile phones, we can get the commonly used data of mobile phones being picked up and use these data.
Knowledge expansion:
The principle of gyroscope is that the direction pointed by the rotating shaft of rotating object will not change without the influence of external force. According to this truth, people use it to keep their direction, and what they make is called a gyroscope. When the gyroscope works, it should be given a force to make it rotate quickly, which can generally reach hundreds of thousands of revolutions per minute and can work for a long time. Then the direction indicated by the shaft is read by various methods, and the data signal is automatically transmitted to the control system.
In real life, the feed motion of gyroscope occurs under the action of gravity moment.