Upload
ankuredkie
View
2.747
Download
0
Embed Size (px)
Citation preview
TECHNOLOGY ROBOTICS SOCIETY
Indian Institute of Technology, Kharagpur
A TUTORIAL ON ROBOTICSSensors
Copyright © Robotix Team, IIT Kharagpur
Basic Parts Of Our Mobile Robot Locomotion system Power supply system Actuators Sensory devices for feedback Sensor Data processing unit Control system
Sensors Analogous to human sensory organs
Eyes, ears, nose, tongue, skin Sensors help the robot knowing its
surroundings better Improves its actions and decision making
ability Provides feedback control
LDR - Light Dependent Resistor Made of cadmium
sulphide Resistance between
two terminals vary depending on the intensity of light
Can be used to differentiate contrast colours
LED – Light Emitting Diodes Used generally with LDRs
to make a complete sensor module.
Act as a source of light for the LDRs.
The main specification of LED are its current rating=20mA, typical cut in voltage=2V,voltage is around 4.5V.
Thermistor Manufactured from the oxides of the
transition metals - manganese, cobalt, copper and nickel
Resistor depends on temperature Commonly available temperature
sensors are LM35,DS1621 thermistor.
IR Photo Diode Detects presence of Infra
Red radiations Used for obstacle proximity
sensing IR Data Communication Used in combination with IR
LEDs
Sensor Interfacing
Light Sensing Module using LED-LDR combination
Sensor Interfacing
Bump Detector Module
An Example - Line Follower A line follower is a robot
capable of tracking a line drawn on a surface
Optical sensors capture the line position at the front end of the robot
The robot is steered to keep it always over the line
Block Layout of Line FollowerOptical Sensor Array
Steering Controller
Left Motor Right Motor
Line Following AlgorithmStep1:Step1: All the sensors are assigned All the sensors are assigned some weight such assome weight such as
Sensor 1 = a1 = 3Sensor 1 = a1 = 3Sensor 2 = a2 = 2Sensor 2 = a2 = 2Sensor 3 = a3 = 1Sensor 3 = a3 = 1Sensor 4 = a4 = -1Sensor 4 = a4 = -1Sensor 5 = a5 = -2Sensor 5 = a5 = -2Sensor 6 = a6 = -3Sensor 6 = a6 = -3
Step2:Step2:Let b1 – b6 denote the state of each Let b1 – b6 denote the state of each
sensor. 0 for white line and 1 for black linesensor. 0 for white line and 1 for black lineStep3:Step3:
Line Position = Line Position = ΣΣaibiaibi
Step4:Step4:Vcm is fixed, Vcm is fixed,
predeterminedpredeterminedωωcm is cm is
proportional to Line proportional to Line positionposition
Step5:Step5:Vl = Vcm + (Vl = Vcm + (ωωcm / a)cm / a)Vr = Vcm – (Vr = Vcm – (ωωcm / a)cm / a)a : Separation between left/right a : Separation between left/right wheelswheels