IR sensor (Line sensor)

Nowadays, in electronic market provides variety of IR sensor. Infrared (IR) sensors have become indispensable tools for several industries. However, not all frequencies of light within the infrared spectrum behave the same. There are a number of methods which can be used to build a line following robot. In general there are three different types of line followers which are single light, two lights, and three lights sensor model. On the other hands, besides using a complete sensor which it can easily find in the market, an infrared LED transmitter and receiver can be used to detect the line.

The reason of selecting this type of IR sensor is because it has good range which is fulfil the requirement for robots. It is very low cost and can be constructed on general purpose PCB. Besides that, it is very small in size which is best for robots. For obtain a good result, the number of transmitter and receiver can be increase. Thus, it has good immunity to ambient light and waves are invisible to eyes.

IR LED is used as a source of infrared rays. It comes in two packages 3mm and 5mm. 3 mm is better as it is require less space. IR sensor is nothing but a diode which is sensitive for infrared radiation. This infrared transmitter and receiver were known as IR Tx-Rx pair.

Pictures below shows the results after done with designing the PCB line, etching, components placement and soldering procedures.

Referring to the picture below, the input for the line sensor circuit is 5volts max. There are 3 pin for voltage output which are Vout 1(V1), Vout 2 (V2) and Vout 3 (V3). These output voltage pins are important to the system because every each of output pin will produce a different output voltage value which is directly connecting to the IC.

When IR sensor detects line, the voltage output is high but when it did not detect any line the output voltage is low. During troubleshooting the circuit, the result when detecting line is 1.59 volts and 0.14 volts is when it not detecting any line. On the other hands, each of voltage output pins control left and right motors.