Hardware Reference
In-Depth Information
When Light Dependent Resistor is inserted into a potenial divider coniguraion, as shown
in the following diagram, the drop in voltage causes a potenial imbalance leading to a
change in voltage. Since the reflectance of white and black color surfaces varies, the change
in voltage can be used to disinguish between black and white colors. This property of Light
Dependent Resistors can be used in our line following robot:
A Light Dependant Resistor in a potential divider configuration
The poteniometer in the potenial divider coniguraion is used to adjust the sensiivity of
Light Dependent Resistors depending upon the surrounding lighing condiions.
Light Dependent Resistors can be used as a sensor to build a line following robot, except
in those cases where the sensor response ime is not trivial. Hence, LDRs cannot be used
in cases where the robot is designed to move at higher speeds.
Light Dependent Resistors have to be completely isolated from light sources other than
the bright white LED. This is to make sure that the LED responds to reflected light from
the bright LED.
Infrared emitter/detector
An infrared (IR) emiter/detector combinaion is the best alternaive to the Light Dependent
Resistors. In both cases (the LDR and IR sensors), the emiter (ultra bright white LED/IR LED)
and the detector (Light Dependent Resistors or photodiode) are arranged next to each other.
