☻ It is a device which measures a physical quantity and converts it into a signal which can be read by an observeor
☻ A robot comes to know its environment through sensors.Properties A sensor should follow the following rules:-
Immunity to error.
Compatibility with the sub-system connected.
Resolution. Sensors used in Robotics :
Light Dependent Resistor(LDR)
Thermistor & other temperature sensors
Various chemical sensorsSo lets see when do we use different sensorsLight Dependent Resistor(LDR)
Also known as a photoresistor.
Its resistance decreases as the intensity of light falling on it increases.
Used in light sensor circuit.
when the Light falls on it, the resistance of the LDR falls, allowing current to pass through it.
so it can be used as voltage divider.
From the first fig where LDR is at top. we see that when light falling on it increases the resistance of LDR decreases so v
out increases.And visa versa.Few important things to note :-
In voltage divider, resistance connected with LDR should be of comparable value .
The value is decided by - R=sqrt(R1*R2)
where R1 and R2 are LDR resistances in presence and absence of light respectively.
Because LDR are very sensitive to light change, we use a black strip around LDR and 2 LedsIR TSOP TSOP Features :
Output active low.
Low power consumtion.
Continuous data transmission possible.
This image shows both IR LED and TSOP
IR LED works as a Transmiter and TSOP as an Receiver
The best example is remote which has IR LED and Television set which has TSOP
The input from TSOP is amplified as the signal may not be too strong.
Normally in market there are also available assembled which gives you a amplified signal.
SRFO4 SONAR SENSOR
The maximum range upto 10m.
Minimum range of about 26 cms.
Low Power Consumtion.
The sonar sensor is very sensitive and very complex to use.
It works on the principle of echo.
These sensor have few applications.
So this is how a photo diode looks like and schematic symbol.
Converts light into voltage or current.
The magnitude of current depends on the intensity of light falling on it.
Photo diode is reverse biased.
Just like LDR,here also voltage divider can be used to generate a signal in the form of voltage so as to make the
device interface able with another subsystem.
Response time is better than LDR.
For avoiding disturbances covering the photodide is advisable.
works almost like LDRApplicationsLDR and photodiode :-
Line follower.IR TSOP :-
TV/VCR remote controls.
Wireless IR transmission over channels.
Obstacle avoider.SONAR :-
helped by Krishna paul