This is a circuit which is able to see the black line on the white floor, and translate the vehicles location in relation to the line that is understandable by the comparator. Here an array of LED & LDR are used under the car. If white surface is there beneath LED then light ray is reflected & detected by the Light Dependent Resistor. Again if there is black surface under the LED no ray is reflected & received by the LDR. So, LDR gives different voltage for this two cases which is caught effectively by the comparator. We use a potentiometer through which the reference voltage of this comparator is set. According to the output of the comparator microprocessor decides the path of the robot.
The LM2904,LM358/LM358A, LM258/LM258A consist of two independent, high gain, internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltage. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage. Application areas include transducer amplifier, DC gain blocks and all the conventional OP-AMP circuits which now can be easily implemented in single power supply system.
Here the figure below shows the sensor circuit using LED & LDR.
We can use any number of sensors.If we use less number of sensors, the robot will face a problem at sharp turning. More the number of sensors, more efficiently the path will be detected.
Distance between sensors depends on the following factors.
1. Number of sensor used.
2. Width of the line.
This is a circuit which supplies the necessary voltages to all the circuits and systems on thevehicle. The power source will be a 9V Battery. We use 9V to drive the motors, and 5V to drive sensors & microcontroller. Here, voltage regulator 7805 is used to get the fixed 5 V DC output. Figure below shows the necessary circuit for 5V power supply.
Implementation of power (5V DC)