With infrared (IR) sensors, can build a line follower robot. The construction and operation of this type is the post’s subject.
Clicking in the button below will open the post about IR sensors.
Line follower with transistors
It is possible to build a line follower robot with only 2 BJT transistors. The necessary materials are:
- 2 TIP122 transistors;
- 6 resistors: 2 of 47Ω, 2 of 330 Ω and 2 of 10 kΩ;
- 6 1N4007 diodes;
- 2 TCRT5000 IR sensors;
- 2 wheels and 2 DC motors with reduction;
- 4 AA batteries and support for 4 batteries;
This is the schematic circuit of electronic part. When the phototransistor receives the reflected light from IR led, the TIP122 transistor is in cut mode and motor stops moving. The 47 Ω resistor serves to avoid TIP122 from heating up. The diodes serve to reduce motor`s speed. If robot goes too fast, it won`t be able to make curves.
This buttons opens the post about how to make printed circuit board.
The board after the processes of drawing, corrosion and piercing.
All components, with the exception of TCRT5000 were welded in the trails side.
The line follower robot ready. Follows a dark line in a light surface.
This is the test track, has 4.8 cm width.
Line follower robot kit
This is a D2-1 kit imported from China. These are all components, the board is the chassi.
Instruction manual shows the schematic.
This robot uses 2 LDRs and 2 red LEDs as sensors. The potentiometers have the function to regulate response of sensors. The sensors output go to LM393 chip, which is a double voltage comparator, has two operacional amplifiers, the operation of this component will be subject to other post. LM393 controls the 8550 transistors as switches and the latter controls DC motors, the D1 and D2 LEDs serve to indicate that the motor is on. This is the track test in opposite side of schematic.
This videos shows the follower line robots in operation.
This other video shows the assemble process.