This robot follows the black line that is drawn on the white surface or follows the white line that is drawn on the black surface. Infrared sensors are used to detect the line. When the infrared signal falls on the white surface, it is reflected and if it falls on the black surface, it is not reflected. This principle is used to scan lines for the robot. All the above systems are controlled by the Microcontroller. The microcontroller receives the signals from the infrared sensors and drives the motors according to the sensor inputs. Two stepper motors are used to drive the robot.
THEORY OF OPERATION:
How to detect a black line The sensors used for the project are Reflective Object Sensors, 0PB710F that are already ready in the Electronic Laboratory. The only sensor consists of an infrared emitting diode and an NPN Darlington phototransistor. When a light emitted from the diode is reflected from an object and back to the phototransistor, output current is produced, depending on the amount of infrared light, which activates the phototransistor base current. In my case, the amount of light reflected in a black line is much less than that of a white background, so we can detect the black line somehow by measuring the current. (This current becomes voltage.)
Ii) How to control a DC motor
Instead of applying a constant voltage through a DC motor, the motor is turned on and off with a fixed voltage (Vcc) applied to the motor. This is done by sending a Pulse Width Modulation (PWM) pulse train to a power MOSFET to turn it on and off. The motor then sees the average voltage while it depends on the duty cycle of the PWM pulses. The speed of rotation is proportional to this average voltage.
By the PWM method, it is easier to control the DC motor than by directly controlling the voltage across it. All we have to do is modulate the pulse width, in ord
BLOCK DIAGRAM :