Authorized Online Retailers:

Buy from US Buy from UK Buy from DE Buy from IT Buy from FR Buy from ES Buy from JP


In this lesson, we will add 5 black/white tracking sensors to the framework built in Lesson 1. If you have not completed installation in Lesson 1, please review Lesson 1

The software in this lesson will read data from these 5 black/white tracking sensors and automatically guide the smart car to move along the black track line in the white ground.

Parts and Devices:

Hardware Installation:
Step 1: Install the smart car basic framework as per Smart Car Lesson 1. If you have already completed installation in Lesson 1, Lesson 2, Lesson 3 and lesson 4, just keep it as is. No need to remove any module installed in Lesson 2, Lesson 3 and lesson 4.

Step 2:  Remove screws on copper pillars and install 5pcs tracking sensor modules at the front of lower car chassis with 5pcs M2.5 plasctic screws, M2.5 plastic pillars and M2.5 plastic nuts. Make sure that every sensor head is over the gaps at the front side of lower car chassis so that the sensor can detect black lines in white ground.

Step 3: From left to right, connect the D0(D zero) pin in tracking sensor module to A0, A1, A2, A3, A4 pin in UNO board. Remember: DO NOT remove any existing wires installed in Smart Car Lesson 1 . Use 1pin male to 5 pins female jumper wires to connect VCC and GND of 5pcs tracking sensor modules. Connect VCC of tracking sensor module to 5V in UNO board, GND to GND. As the following photo shows:

Step 4: Fix the screws on copper pillars to connect upper chassis to lower chassis.

Software Installation:
Step 1: Install latest Arduino IDE (If you have Arduino IDE version after 1.1.16, please skip this step). Download Arduino IDE from , then install the software.

Step 2: Download Lesson 4 tracking smart car sample code from , unzip the download zip file, you will see a folder called smartcar-lesson4 .

Step 3: Connect UNO R3 board to PC with USB cable, Open Arduino IDE -> click file -> click Open -> choose code "smartcar-lesson4.ino" in smartcar-lesson4 folder, load the code into arduino.

Step 4: Choose corresponding board/port for your project,upload the sketch to the board.

Step 5: Adjust the sensitivity of tracking sensor modules. Turn on and hold the car and adjust the potentiometer on the tracking sensor with cross screwdriver until you get the best sensitivity status: the signal indicate LED light will turn on when sensor is above white ground, and the signal LED will turn off when the sensor is above black track


Prepare a black track (the width of the black track is more than 20mm and less than 30mm) in white ground. Please note, the bend angle of track can't be larger than 90 degree. If the angle is too large, the car will move out of the track.

Turn on the car and put the middle of tracking sensor module facing over black track, and then the car will move along the black track.

Trouble Shooting:

If your car can move but does not follow the black track line, normally it meansyour tracking sensors connection to Uno board has some problem. To help use to find out which sensor connection is wrong, we developped following diagnosis code to test the sensors.

Download link:

After load above code to Arduino, open the serial monitor window in upper right corner of your Arduino IDE. Now put a white paper and use a black mark pen to draw a one cm wide black line. We need use this black line to test each sensor signal received by Arduino board.

When you put black line under Left5 sensor (1st sensor frome right), and other 4 sensors all above white paper, Now Left 5 Sensor Green LED should be off. the Serial monitor will show '0 0 0 0 1'. as per following picture.

If Serial monitor does not show 0 0 0 0 1(i.e it shows 0 0 0 0 0 instead), it means Left5 sensor connection to UNO board is wrong. Read Hardware Installaing Step 3, we found that Left5 should connect to D10. So we need check Left 5 sensor connection jumper wire to UNO board D10, and see if the wire is loose or not connected properly.

Repeat above procedure, put black line paper under Left 4, Left 3, Left2 and Left 1 sensor. you will find which sensor connection is wrong. Afte all sensor connection is connected properly, your tracking program will work properly.