8 Channel Tracking Sensor Module Board Trace Module Infrared Detection

The IR Sensor Array of 8 consists of 8 IR LED/phototransistor pairs mounted on a 0.375″ pitch. These sensors are a great detector for line-following robots and grid navigation robots. All the LED s in the module are connected in series to halve the current consumption. And an IC allows the LEDs to turn off for additional sensing or power-savings options. Each sensor generates separate digital I/O as well as Analog Output also.

The module was designed as a perfect carrier for eight IR emitter and receiver (photoresistor/photodiodes) pairs evenly spaced at a distance of 15mm intervals. Thus used as a general-purpose proximity IR or reflectance sensor.  Each sensor senses digital output and can sense the presence of a line indicated with a 5V logic output. On reading the digital state of the eight sensors, the user can not only detect the line but also determine how far the centre of the robot is from the line. When all sensors sense the line, the robot is at an intersection

Each phototransistor equipped with a pull-up resistor in the module forms a voltage divider and produces an analogue voltage output between 0 to 5V as the function of the reflectance sensor. The lower the output voltage greater will be the reflection.  Even though all the LED s are paired, the output is independent of each other. The LEDs in the module are controlled by MOSFET with a gate normally pulled high. This allows LEDs to turn off by setting the MOSFET gate at low voltage. An onboard potentiometer in the sensor allows adjusting the sensitivity of the individual sensors. It will be advantageous if we turn OFF the LED for limiting power consumption when the sensors are not in use or for varying the effective brightness of the LEDs through PWM control.