Proximity Sensors for Robots

Presented by
Pradeeshkumar P. D
Roll no: 38
S-7 Mechanical

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Contents
Introduction
What is a sensor
Proximity sensors
Working principles
Sensor input to the robot
Other applications
Conclusion

Introduction
Robot, once a creature of science fiction, is today a reality. It is the off-shoot of the second industrial revolution.
The robot is a programmable machine which can be programmed to a sequence of mechanical motions and it can repeat that motion sequence over and over until reprogrammed to perform some other job.
To carry out its task, a robot must have access to information on predetermined parameters of the environment. Sensors are used to provide this information
What is a sensor?
The basic function of an electronic sensor is to measure some feature of the world, such as light, sound, or pressure and convert that measurement into an electrical signal, usually a voltage or current.
There are two basic types of sensors:
analog
digital.


Proximity sensors
Proximity sensing is the ability of a robot to tell when it is near an object, or when something is near it. This sense keeps a robot from running into things. It can also be used to measure the distance from a robot to some object.
Proximity sensors currently come in four flavors:
1.Inductive
2.Capacitive
3.Uitrasonic
4. Optical

Principles of Operation for Inductive Proximity Sensors
Correction Factors for Inductive sensors
Target Material Approximate
Correction Factor
Mild Steel 1.0
Stainless Ste 0.85
Brass 0.50
Aluminum 0.45
Copper 0.40
Principles of Operation for Capacitive Proximity Sensors
Dielectric Constants of Common Industrial Materials
Material Dielectric constant
Air 1.000264
Glass 3.7–10
Paper 1.6–2.6
Rubber 2.5–35
Sand 3–5
Water 80
Wood, Dry 2–7
Wood, Wet 10–30
Principles of Operation for Ultrasonic Proximity Sensors
Principles of Operation for Optical Proximity Sensors
Sensor Inputs to the Robot
The Robot control system contains input ports for both analog and digital sensors.
The analog ports measure the voltage and convert it to a number between 0 and 255, corresponding to input voltage levels between 0 and 5 Volts. The conversion scale is linear, so a voltage of 2.5 volts would generate an output value of 127 or 128.
The digital ports, however, convert an input voltage to just two output values, Zero and One. If the voltage on a digital port is less than 2.5 Volts, the output will be 0, while if the input is greater than 2.5 Volts, the output will be 1.

Other applications
Machine tools
Wood industry
Petroleum industry-Valve position
Conveyor belts
Food industry
Printing
Stainless steel sheet welder
Online parts soldering
Railroad Yard position sensing

Conclusion
With the help of sensors, automation in robots, its navigation, operational capabilities like packing, assembling, loading etc, and its integration with human workers have been achieved. Sensors present a wide range of applications in future automation technologies. They help in exploration of space, defence applications, medical applications, research fields etc, there by acquiring complete automation in all respects. Thus the future technological advancements greatly depend on sensors.