Infrared sensors Week 5 - Summary

This is the last week of our project. We have already finished all of the circuit building and testing. The blog this week is a summary.

The subject of this project is to study the function of the infrared sensors, RE200b with a situation which is to monitor the elder people when they fall down so that it can protect the safety of the elder people. When the sensor get the signal input, it will output a signal and the signal will run through a circuit to amplify the signal and display the signal by using a LED or a buzzer. In our final product, we have already achieve the fundamental function and it can measure the signal within 1-1.5 meters.
 

In the past five weeks, we search the information of the infrared sensors and build our circuit, also we use PSpice to simulate our circuit. During the working days, we met lots of problems, and the biggest problem was to make the results of the circuit were same with the simulation results. The important thing is that we work together and have a discussion many times. At last, we solved the problem and finished the project successfully because of our teamwork. This is a group project, so the ability of the teamwork is very important.

For the product we have designed, it can be used in many ways, not only to monitor the safety of the elder people, it can be used in the army and the medical field. The advantages of the infrared sensor are easy to operate and economical. Our group members have got a familiar with the operation of the infrared sensor, also improve our teamwork ability. In addition, this is a useful also unforgettable experience in our year 2 study, and it is significant for our future study in the electrical field. 

Infrared sensors Week 4 - Circuit testing

This is the fourth week of our group project. We have completed the circuit building on the breadboard fundamentally. Our main work was to test the circuit and observed the output signal of different amplifiers by the oscilloscope. We moved our hands over the sensor and got the following results as showed from the figure 1 to figure 3. During the testing, we had to adjust different amplitudes and frequencies because of the effect of the amplifiers in order to get the obvious implus. 

Figure 1: The output signal of the first amplifier.

Figure 2: The output signal of the second amplifier.

Figure 3: The output signal of the third amplifier.

We also transcribed a video of the output signal of the third amplifier, the video below shows the results.

Then, we added a LED on the circuit and tested the circuit when people walked through the sensor. The video below shows the experiment results.

There were also some disadvantages, the sensor was not sensitive enough, and the distance from people to the sensor was limited. The group suspected it was the problem with circuit connection. in addition, the signal could no tlast for a long time. 

In summary, we finished all of the circuit building in this week, in order to get the reasonable result, we tested the circuit again and again. We corrected the wrong direction of the movement signals and now signals as the simulation shown can be basically displayed on the oscilloscope. Appreciate size of lens were found. Week 5 will be the last week, all technical things should be done. We will try to overcome those challenges and get satisfying results.

Infrared sensors Week 3- Circuit building

This is the third week of our project. We had finished the simulation of the circuit in the last week. We started to build circuit on the breadboard in this week and test the circuit with a sine wave as the input by using the function generator. The output signal was measured by the oscilloscope. The figure below were the results.

Figure 1: The first input and output signal

Figure 2: The second input and output signal

Figure 3: The third input and output signal

Comparing the actual results with the simulation results, we did not get the third results which would need future study, but the other results were the same.

The biggest challenge the group are facing in this week was that the problems with the circuit building. The final output was just a straight line but not a waveform while getting close to the sensor with hands. The biggest problem is that the output of the third amplifier which is the comparator part is not consistent with the PSpice simulation.

In summary, the group completes the circuit building for three parts, including the signal input part, amplifier part and comparator part. In addition, the PSpice simulation has been checked. The group will finish the circuit building and finish the project. The group members will discuss the report writing and presentation.

Infrared sensors Week 2-PSpice simulation and circuit connection

Week 2

This is the second week of our group project. In the last week, we had tried to build the circuit and simulated the circuit on the PS-pice, but we did not finished them. In this week, we designed the circuit successfully and got the simulation results.

Firstly, we built the circuit step by step and decided to use the circuit as the figure 1 showed. There were three parts in this circuit, including signal input, amplifier and comparator. 

Figure 1: The experiment circuit

Then, the circuit was simulated by using PS-pice, we used the sine waves as the input signal in order to simulate the circuit. We simulated the different outputs of the amplifiers respectively and the results are showed in the figure 2 to figure 4. The input sin wave was represented as the red line, and the white was the output signal.

Figure 2: The first output signal of the first amplifier.

Figure 3: The second output signal of the second amplifier.

Figure 4: The third output signal of the third amplifier.

However, there are some problems need to be solved. There was a phase difference between the input and output of the first stage amplifier which the group should explain later.

In summary, our group completed the PS-pice simulation as planning in this week. After a week’s work, the group obtained simulation images which should be shown on the oscilloscope. Also, we finished the initial circuit connection on the breadboard, though there is something wrong with the output of the circuit building. In next week, the main task is that dealing with the problems with the circuit, make sure that the output on oscilloscope is as the same as PS-pice simulations shown.