PIR Sensors and Their Applications for Human Motion Detection

In week 5, the project has almost finished. So the main task of this week is to testing the system more times and to find the existing mistakes. It should be noted that the poster is already done, which can be seen in Figure 1. Figure 1: The Poster During the testing, the detecting distance of PIR was set from 1 to 3 meters. When a tester was passing by the circuit, the sensors would react and LED screen will show the figures. When another tester who is thinner passing by will cause different results. Here are the pictures showing the process of the testing and the consequent waveform from oscilloscope. Figure 2: 100cm Figure 3：150cm Figure 4: 200cm Figure 5: 250cm Figure 6: 300cm In addition, our group have built three identical circuits to test the movements of people falling down. The basic theory is that when people fall down, only the sensor at the bottom will receive the signal. At the same time, when a person walks through the system...

In the previous three weeks, there two circuits which have been completed. Because the circuit is too complicated and there must be some tiny mistakes in the circuit on the breadboard, the sensor cannot detect the motions sensitively and the waveforms on oscilloscope are full of noise. Therefore, what was concerned on this week was to do some improvement of the circuits and then make a testing plan to record the data. It can be observed that if the tester is a little far from the sensor, there would be a very slight change on the output signal. In other words, the testing distance of the sensor is too short. In order to solve this problem, a lens was used to put over the sensor. The lens is able to centralize the light so that it can detect the changes of light more easily. In this way, the detecting distance is increased effectively. It can be seen in Figure 1. Figure 1 What need to be focused on is how to connect these two circuits and make them work simultaneously to det...