Here we are talking about sensors used in the Robotics. As we know that robotics uses the sensors to its maximum limits, various types of sensors are used for various purposes in various application in various locations.

Classification of Sensors Used In Robotics Based On Physical Input Quantity:

1. Tactile sensor.
2. Proximity Sensors.
3. Range sensors.
4. Navigation sensors.
5. Vision sensors.
6. Miscellaneous sensors.

1. Tactile Sensors:

Tactile sensors are devices which indicate contact between themselves and some other solid object-in this case, an obstacle. This kind of sensors can be subdivided into two more sutypes:

• Touch Sensors:

They are used to indicate that contact has been made between two objects without regard to the magnitude of the contraction force. A binary output signal indicates whether or not a contact has been made with the object.

Ex:- limit switches, micro switches etc.

• Force Sensors:

They are also called as stress sensors. They not only indicate that the contact has been made but also the magnitude of the contact force between the two objects.

The capacity to measure forces permits the robot to perform a number of tasks. These include the capability to grasp parts of different sizes in material handling, machine loading and assembly work, applying the appropriate level of force for the given part. In assembly applications, force sensing could be used to determine if screws have become cross-headed or if parts are jammed.

2. Proximity Sensors:

Proximity sensors are devices that indicate when an object is close to other. How close the object must be in order to activate the sensor depends upon the particular device. The distances can be anywhere from few millimeters to several feet.

Proximity sensors can be used to detect the presence or absence of a work part or object. Another important application is sensing human beings in the robot work cell. Range sensors will determine the location of an object (work part) in relation to the robot.

Ex:- optical proximity sensors, acoustical sensors, magnetic field proximity sensors.

3. Range Sensors:

This is type of sensors which can be considered very near to proximity sensors. Range sensors measure the distance between the object and the sensor. These sensors are located on the wrist or end-effecter as these are the moving parts of the robot.

4. Navigation Sensors:

As name navigation indicates, this is kind of sensors which can be used for estimate positioning of objects. This kind of sensors can be classified in two main subclasses.

• Relative Positioning Measurement:

They measure the signal within the robot itself. They can be again subdivided into:

• Proprioaptive sensor.
• Inertial navigation systems – Gyroscopes and Accelerometers.
• Odeometry.

• Absolute Positioning Measurement:

As name absolute, this sensors take measurements from some kind of fixed or universally fixed datum. Types Under This kind of sensors is:

• Magnetic Compasses.
• Global Positioning Systems (GPS).
• Active Beacons – triangulation.
• Landmark Navigation.
• Model Matching – Map matching.

5. Vision Sensors:

Machine vision is concerned with sensing of machine vision and its interpretation by a computer. The typical vision system consists of the C.C.D. camera and digitizing hardware, a digital computer and software necessary to interface them. This interface hardware and software is after referred to as a preprocesser. The operation of the vision system consists of 3 functions :

a) Sensing and digitizing data.

b) Image processing and analysis

c) Application

For object recognition, along with processing, robot programming is also necessary.

6. Miscellaneous Sensors:

This category covers the remaining types of sensors and transducers that might be used for interlocks and other purpose.

This category includes devices with the capability to sense variables such as temperature, pressure, fluid flow, velocity and electrical properties. Hence this category includes sensors and transducers like tachometers. LVDT, Pr gauges etc.

Related Topics and Articles:

1. Autonomous Mobile Robots Overview
2. Ultrasonic Level Sensor
3. Linear Variable Differential Transformer-LVDT

What is Coating?

The covering or spreading of a layer of a material on the component surface is called coating. Since every object expected to meet Variety of specification which could be conflicting with each other. To overcome this problem coating is utilized.

Various Methods of Coating or Coating Deposition:

• Spray Deposition Process.
• Chemical Vapour Deposition Process.
• Physical Vapour Deposition Process.

Here, in this topic we will see Physical Vapour Deposition Process.

PVD:

PVD stands for Physical Vapour Deposition. This method utilizes vacuum technology. PVD is the technology of using physical way to coat materials on to the substrates in the condition of vacuum.

PVD Process Description:

Above figure explains the PVD coating method in brief. Initial and final phase is called as condensed phase and final phase is achieved through the series of phases and process like, gaseous, evaporation and condensation respectively.

Electron Beam Physical Vapour Deposition:

Electron Beam Physical Vapor Deposition is also called as EB PVD process. EB-PVD is a derivative of the electron beam melting technique.

EB-PVD is a form of PVD in which a target anode is bombarded with an electron beam given off by a electron gun under high vacuum.

EB-PVD offers high flexibility in depositing ceramic and metallic.
EBPVD is a relatively new material coating method that produces good results. It is particularly useful in thermal barrier coatings in aircraft turbine blades and in protective coatings on cutting tools.
The increased deposition rates and variety of materials and techniques of the EBPVD process provide an opportunity to broaden the application of this technology into the marketplaces.

Advantages of EB-PVD:

1. The deposition rate in this process can be as low as 1 nm per minute to as high as few micrometers per minute.
2. The deposit has a columnar grains structure.
3. Smooth surface, better interaction with the substrate.
4. The EB-PVD process offers extensive possibilities for controlling variations in the structure.
5. Relatively high deposition rates.

Applications of EB-PVD Coating:

EB-PVD coating have two kinds of major applications which are 1. Decorative Coating. and 2. Tool Coating.

Decorative Coating Applications:

1. For decorative application ,gold is deposited after depositing TIN.
2. The system has also been used for coating of telescopic mirrors.

Applications of PVD in Turbine Industry:

1. To improve life or work temperature of blades.They are coated by the use of thermal barrier coatings (TBCs) over metallic substrate.
2. TBC is the thermal insulator.
3. Zirconia is used as ceramic layer.
4. Tablets of an alloy of Ni, Cr and Al are evaporated using the energy of an electron beam and then condensed on the substrate.

Applications in Machine Tool and Forging Die Industries:

1. Metallic carbides, nitrides, and oxides have long been known to be very hard, wear resistant materials.
2. Applying these hard coatings to tool steels and tungsten carbide-cobalt cutting inserts can increase the tool life by high percent.

Limitations of Physical Vapour Deposition Coating:

1. The process is expensive.
2. Possible to coat only outer surface of complex geometries.
3. At present the process is dependent on highly trained users.
4. Filament degradation in the electron gun.

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Introduction to Mobile Robots:

Robotics is very speedily growing and widely used branch of engineering. It have very large set of applications around, like in automobiles industry, electronics, computer industries, mechanical industries etc.

Now, we will move towards robots. Man is successful in creating the stationary robot and making its use for various applications. For example, robotic arm. Robotic arm is used in the automobile industries and electronics industries for automation purpose. These arms are very skilled in their work and perform the task in almost ideal time. Moreover, their operating cost is much less than the skilled human worker.

However, the main limitation of a robotic arm type stationary robots is that, it has to operate only in a defined area. Mobile robots are next to stationary robotic arms.

Mobile Robots/ Movable Robots:

As discussed before, mobile robot is movable, so it is necessary to have some locomotion system in it. Up till now, wheels and tracks are best options. Now a days, robots designers are looking towards newer ways of locomotion due to complexity in the operation of robot task. These ways includes, designing the robot having legs. Such robots have wider adaptation with working environment. Legged robots have necessary applications in the Defense and Aerospace Applications (Like NASA Projects). As stable robots start moving around in the uneven field, new problem arise which regard to the balancing of robot. This needs the installation of Leveling Mechanism in it.

Controlling The Mobile Robots:

No doubt, that to make robot work smarter and smarter designer have to install a wide types of sensors in it like distance sensors, level sensors, weight sensors etc. These sensors have the whole responsibility that the device will work as per design or not.

Mobile robots can be completely or partially controlled by the remote control devices. These devices communicates with robots through infrared or some similar medias. If area of working of robots is quite defined then direct wires could be used. But this limits the robot working area.

Again, robots can be autonomously controlled too. This is achieved by providing the program which pre-defines the robot task through program. Autonomous robots can act on their own, independent of any controller. The basic idea is to program the robot to respond to a certain way to outside stimuli.

General Applications of Mobile Robots:

Simple robots are used in homes and offices e.g. land moving robots whereas advanced autonomous robots like rover are used in space exploration. Micro robots are used for defense purposes and navigation. Mobile robots with stable legs will an important step in building stable humanoids.

Related Topics and Articles:

1. Sensors In Robotics

Ultrasonic Sensor-Electronics Seminar Topic:

Seminar on Ultrasonic Devices need Following Things.

• What is Sensor?
• Ultrasonic Waves?
• Properties.
• Principle and Working of Ultrasonic Devices.
• Applications.
• Explanation of some applications.

Some applications of Ultrasonics are as Below:

1. Ultrasonic Level Sensor.
2. Ultrasonic Distance Sensor.
3. Ultrasonic Flow Meters.

Sensors:

Sensor is Transducer Device which can sense the change in Pressure, Temperature etc. physical Quantities and turn them into readable digital or analogue quantity. Sensors are responsible for making simple devices and machines into SMART DEVICES or Machines.

What are Ultrasonic Waves?

Now, we discuss about Ultrasonic Devices. Here are some of major properties of Ultrasonic Waves.

1. First of all, Ultrasonic Waves are not the Electromagnetic Waves. They are mechanical waves.
2. As being the mechanical waves, they need medium for their propagation.
3. Their frequency is > 20kHz.
4. As high frequency, wavelength is ought to be small.
5. High penetrative properties.

Ultrasonic Sensors:

Ultrasonic Sensors generates high frequency sound waves and evaluates the echo which is received back by the sensor. They typically comprises at least one ultrasonic transducer which transforms electrical energy into sound and, in reverse, sound into electrical energy. An ultrasonic transducer consists of a transmitter, a receiver & a processing unit. It generates frequency range of 30kHz-100kHz.

Principle of Working For Ultrasonic Sensor:

1. Transducer typically have a piezoelectric ceramic element (material) that converts an excitation electrical signal into ultrasonic energy bursts or vibrations at very high frequency.
2. Conversely, generates voltage whenever subjected to vibrations.
3. Piezoelectric ceramic element such as lead-zirconate-titanate (PZT) having operating frequency close to 32kHz.

Applications:

1. Detecting and identifying solid objects.
2. Measuring the shape and orientation of a work-piece.
3. Distance measurement.
4. Room surveillance.
5. Flow measurement.
6. Level measurement of a tank.

Related Topics and Articles:

1. Ultrasonic Distance Sensing
2. Ultrasonic Level Sensor
3. Ultrasonic Flowmeters

Ultrasonic Flowmeters:

Already we have seen some of the ultrasonic devices before like Ultrasonic Level Sensor and Ultrasonic Distance Sensing. Now, I am going to explain one more ultrasonic device here. Ultrasonic Flow-meters are used to detect the speed of flow or subsequently quantity passed through the flow in given time.

Types of Ultrasonic Flowmeter:

1. Transit Time Type.
2. Doppler Frequency Shift Type.

1. Transit Time Type Ultrasonic Flowmeters:

In this type, two sensors are mounted on the pipe or channel. They send and receive the ultrasonic pulses simultaneously. When the speed of flow is zero or flow is steady, both the sensors receive the reflected pulses at the same time. Vice versa, when the fluid is in motion, sensors receive the pulse with delay between them. This delay is called as transit time difference. This transit time difference is directly proportional to velocity of flow and hence the volume of flow per unit time.

2. Doppler Frequency Shift Method:

Doppler effect could be explained as the frequencies of received sound waves depends on the motion of the source or observer relative to the propagating medium. The transmitter transmits ultrasonic waves. These are reflected from particles and bubbles. Frequency shifting takes place in reflected wave which is linearly proportional to the rate of flow of materials.

Advantages:

1. The flow of pure water, wash water, sewage, process liquids, oils, and other light homogeneous liquids can be measured.
2. It have no moving parts and hence have very less or no maintenance.
3. Can be used for variety of pipes.
4. It have flexibility to be used on existing pipelines.
5. It can be used as a portable device.
6. It does not have any contact with liquid and hence no danger from corrosive liquids.

Seminar on Ultrasonic Flow meter:

Above is given the information about ultrasonic flow meters. Here are short framework for seminar on ultrasonic flowmeter.

1. Introduction to Ultrasonics.
2. Ultrasonics Properties.
3. Ultrasonic Flowmeter.
4. Construction and working.
5. Types.
6. Transit time type.
7. Doppler Frequency Shift Method.
8. Advantages.
9. Limitations.
10. Applications.

Related Topics and Articles:

1. Ultrasonic Devices
2. Ultrasonic Distance Sensing
3. Ultrasonic Level Sensor

Introduction:

In previous article, we studied the Ultrasonic Level Sensors and its details. Now, I am going to explain the another ultrasonic device which works almost similar way to before. Ultrasonic Distance Sensor.

Ultrasonic Distance Sensing:

Ultrasonic Sensors are devices used to take measurements of Remote Distances or we call it as remote distance sensing. Ultrasonic sensing is based on time of flight principle. The transmitter produces the ultrasonic sound or burst or noise, which travels away from source and it enconters the barriers it gets reflected back. Then it is received by receiver.

Whole important topic here is Time Between Wave Produced and Wave Received. This time is used to calculate the distance between the ultrasonic device and obstruction. Other some constants like speed of ultrasonic sound in the air, humidity etc. are major factors in this calculation. If there is a relative movement between the source and the reflector, Doppler Effect can be employed to measure the distance.

Principle of Working of Ultrasonic Distance Sensor:

Ultrasonic sensors work on a principle similar to radar or SONAR which evaluate attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object.

Formula For Ultrasonic Device Measurement:

d=(vt cos θ)/2

where;

d = Final distance,

t= time,

θ = angle of incidence,

Advantages:

1. Ultrasonic Distance measurement devices are more efficient.
2. Ultrasonic Distance measurement devices produce reliable accuracy.
3. Ultrasonic Distance measurement devices have robust construction and have long life of operation.
4. Ultrasonic Distance measurement devices have better accuracy than the other remote distance measuring devices.
5. Ultrasonic Distance measurement devices produce results faster than other devices.
6. Most important thing about Ultrasonic Distance measurement devices is that, they can produce result without interfering the object.

Disadvantages:

1. Ultrasonic Distance measurement devices have limitations when there is density of matter or medium is not consistant.
2. Also the reading may get distorted due to shapes of solids to be measured as reflection of ultrasonic wave is mostly dependent on shape of solid object which is treated as obstruction.

Applications:

Ultrasonic Distance measurement devices have many applications of which most popular are SONAR, Submarine Signaling, robotics etc.

Ultrasonic Distance measurement devices as Electronics Seminar Topics:

Ultrasonic Distance measurement seminar must contain following things.

1. Ultrasonic Sound Introduction.
2. Ultrasonic Devices.
3. Construction and working of Ultrasonic Device.
4. Principle of working.
5. Advantages.
6. Limitations.
7. Applications.

Related Topics and Articles:

1. Ultrasonic Devices
2. Ultrasonic Flowmeters
3. Ultrasonic Level Sensor

Seminar on Ultrasonic Level Sensor:

Ultrasonic Level Sensor is good seminar topic for Electronics Engineering:

1. What is Sensor?
2. Ultrasonic Level Sensor
3. Construction.
4. Working.
5. Advantages.
6. Limitations.
7. Applications.

What is Sensor or Transducer:

Transducer is device which converts the mechanical signal to the electrical signal. Transducer includes various devices like LVDT, tachogenerator, RVDT etc.

Ultrasonic Level Sensor:

Ultrasonic Level Sensor is the device which is used to measure the level of matter in tank or similar. As name suggest, it uses the ultrasonic waves for this measurement.

Construction and Working of Ultrasonic Level Sensor :

Ultrasonic Level Sensor is consist of two main parts viz. transmitter and receiver. The assembly is placed on the tank in which level is to be measured. The transmitter directs the sound waves to the matter and those waves gets reflected back from its surface. Receiver receives the waves and counts down the time delay between the transmission and back receive. From this data and some standard data like speed of ultrasonic sound in the air it finds the distance of level of matter from the sensor.

This sensor provides very fast and reliable data output. Whole answer is mainly dependent upon time delay or lag. The ultrasonic sound is created by the Piezoelectric crystal inside the sensor. It converts electrical energy to ultrasonic sound energy.

Types of Ultrasonic Level Sensor:

1. Continuous Level Sensor:

Continuous Level Sensor can monitor continuously for change in level. In this the phase of emission of waves, their reception and calculation of level is ongoing process.

2. Point Level Sensor

Apart from continuous level sensor, Point level sensor is fire up type. It emits the sound, receives it and calculates the depth for one time. Its name can explain it.

Advantages:

1. Non disturbing technique.
2. Can be used for wide range of things like solid and liquids with wide range of viscosity.
3. Low price.
4. High functionality.
5. Very accurate and low error.
6. Long life instrument.
7. Can measure the level of different liquids having different densities in same tank.

Limitations:

1. Sensor mounting must be properly done.
2. Tank should be free from obstacles otherwise it may cause error in measurement.
3. Result may get affected due to change in temperature or pressure inside the tank or container.

Applications:

1. Automatic pump control.
2. Flow measurement.
3. open channel flow measurement.
4. Used in water/waste applications.

Related Topics and Articles:

1. Ultrasonic Devices
2. Ultrasonic Distance Sensing
3. Ultrasonic Flowmeters

Principle of RVDT:

RVDT is used where precise angular movement is to be measured. RVDT uses the same principle as the LVDT except that, LVDT is for linear measurement while RVDT is for Angular one.

Construction and Working of RVDT:

RVDT is almost identical in the construction with LVDT. The ferrite core in LVDT is replaced by heart or cardiode shaped core. This core is mounted on the shaft or plunger which is capable of rotating. This rotational movement of the shaft creates the imbalance in the external circuit and this imbalance signal is used to measure the angular displacement of the shaft. RVDT give linear output up to displacement of +-40 degree. Then output starts becoming nonlinear.

Applications:

1. RVDT in the signal conditioning as RVDT Conditioner.
2. RVDT as the position sensor.

Examples:

1. Quarter Turn Valve.
2. Mail Sorters.
3. Fractional Shaft measurements.
4. Actuator position sensing in the Aircraft.
5. Marine, Constructional and Agricultural vehicles.

Advantages of RVDT:

1. Low cost.
2. Solid and Robust construction makes it to work in different environments.
3. No frictional resistance, so high accuracy over long time duration.
4. Negligible hysteresis.
5. Excellent reproducibility.

Disadvantages of RVDT:

1. Contact between plunger and measuring surface is always not possible.
2. RVDT provide linear output for about +-40 degree which limits its usability.

Related Topics and Articles:

1. Linear Variable Differential Transformer-LVDT
2. Ultrasonic Level Sensor
3. Ultrasonic Distance Sensing

What is LVDT?

The major use of LVDT is to convert the Rectilinear Physical Motion into Equivalent electrical signal. So LVDT is the sort of transducer which, by means of change in the electrical field of charged coil, changes the output and this change in the output is used to measure the displacement of the object.

Construction of LVDT:

LVDT is provided with two windings

1. Primary Winding.
2. Secondary Winding.

The plunger is provided in the centre which is capable of having linear motion. The ferrite core is mounted on this core which remains in the centre and equidistant form all windings at zero displacement. When this plunger moves towards left or right the imbalance is created in the external circuit connected to measure and this signal is used to measure the displacement of the plunger.

Application of LVDT:

1. LVDTs are used for position feedback in servomechanisms.
2. For measurement in automated machine tools.
3. For many other industrial and scientific applications.

Practical Examples of LVDT:

1. Soil Strength Testing Machine.
2. Weighing Machine.
3. Robot Manipulator.
4. Robot Cleaner.
5. Pill Making Machine.

Limitation:

Major restriction of LVDT is that it can not measure the rotary displacement. But this restriction of LVDT can be overcome by making some change in its construction. i.e. by RVDT(Rotary Variable Displacement Transformer).

Related Topics and Articles:

1. Rotary Variable Differential Transformer-RVDT
2. Ultrasonic Level Sensor
3. Sensors In Robotics

Introduction to E-Bomb:

An e-bomb (electromagnetic bomb) is a weapon that uses an intense electromagnetic field to create a brief pulse of energy that affects electronic circuitry without harming humans or buildings. At low levels, the pulse temporarily disables electronics systems; mid-range levels corrupt computer data. Very high levels completely destroy electronic circuitry, thus disabling any type of machine that uses electricity, including computers, radios, and ignition systems in vehicles. Although not directly lethal, an e-bomb would devastate any target that relies upon electricity: a category encompassing any potential military target and most civilian areas of the world as well.

The concept behind the e-bomb arose from nuclear weaponry research in the 1950s. When the U.S. military tested hydrogen bombs over the Pacific Ocean, streetlights were blown out hundreds of miles away and radio equipment was affected as far as away as Australia. Although at the time these effects were considered incidental, since that time researchers have sought a means of focusing that energy.

EMP:

EMP is the Electromagnetic Pulse. It is Pulse of energy produces a powerful electromagnetic field, particularly within the vicinity of the weapon burst. The field can be sufficiently strong to produce short lived transient voltages of thousands of Volts (ie kiloVolts) on exposed electrical conductors, such as wires, or conductive tracks on printed circuit boards, where exposed.

Who is prone to E-Bomb:

Computers used in data processing systems, communications systems, displays, industrial control applications, including road and rail signalling, and those embedded in military equipment, such as signal processors, electronic flight controls and digital engine control systems, are all potentially vulnerable to the EMP effect.

Other Imporatant Topics in Electromagnetic Bomb:

• Targetting and Delivery of Electromagnetic Bomb
• Defence Against the Electromagnetic Bomb
• Limitation of Electromagnetic Bomb

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