Fig. 5.62 shows the basic principle of how a rotor moves in steps in the case of a permanent magnet rotor. Consider a four stator poles and permanent magnet rotor, as shown in fig. 5.62(b). To start with in step 0, the rotor is in equilibrium since opposite poles are adjacent to each other and hence attracts each other. The rotor can remain in this position and can with stand the opposing torque called holding torque until the magnetization of the stator poles are changed. Once the magnetization of the stator poles are changed (step 0 to step 1) a troque is induced to the rotor causing it to move by 90° in the CW direction and the next equilibrium position is achieved as shown in step 1. When the magnetization is again changed (step 1 to step 2) again a torque is induced in the rotor and it rotates by another 90° and another equilibrium position is obtained as shown in step 2. Successive change of magnetization of stator poles thus rotate the poles in steps of 90°. The direction of rotation of the rotor depends on the direction of sequencing of magnetization of poles, i.e., counter clockwise sequence of magnetization of stator poles, rotates the rotor in CCW direction.
Variable reluctance stepper motor
The variable reluctance stepper motor has a ferro- magnetic rotor rather than a permanent magnet rotor fig. 5.63. Motion and holding are results of minimization of the magnetic reluctance between the stator and the rotor poles. The number of poles on the rotor will always be smaller in number than that on the stator. When current is passed through a pair of stator poles having maximum reluctance path, magnetic field is produced with lines offered trying to shorten themselves, rotates the rotor until the stator and rotor poles lines up which will be the shortest or minimum reluctance path. The steps of angles that are generally obtained with this type of motor is 7.5° or 15°. A variable reluctance motor has the advantage of a low rotor inertia and hence faster dynamic response.
Hybrid Stepper motor : This combines the feature of both permanent magnet and variable reluctance stepper motors. It consists of a permanent magnet mounted inside iron caps. These caps have teeth cut on it as shown in fig. 5.64. This unit forms the rotor of the hybrid stepper motor. The rotor unit itself has minimum reluctance position in response to a pair of energized stator coils. Such motors find its application extensively in high accuracy positioning (e.g., computer hard disc), with a typical step angles of 0.9° and 1.8°.

Stepper motors
A stepper motor is a special type of d.c motor that produces rotation at equal angles called step's for each digital pulse supplied to its input. For example if a pulse can produce a rotation of 10o then 36 pulses will produce one rotation or 360°. Number and rate of the pulse control the position and speed of the motor shaft. Generally stepper motors are manufactured with steps per revolution of 12, 24, 72, 144, 180 and 200 resulting in shaft increments of 30°, 15°, 5°, 2.5° 2° and 1.8° per step. Special micro-stepping circuitry is sometime provided to allow many more steps per revolution, offer 10,000 steps/revolution or even more.
Performance characteristics
The following are the performance characteristics of a stepper motor.
a. Rotation in both directions
b. Precision angular incremental changes
c. Holding torque at zero speed
d. Capability of digital control
Classification of stepper motor
a. Permanent magnet
b. Variable reluctance and
c. Hybrid type
The other classification are
a. Bipolar stepper motor and
b. Unipolar stepper motor
Permanent magnet stepper motor: In this type the stator consists of wound poles and the rotor poles are permanent magnets. The permanent magnet motor has the advantage of a small residual holding torque called the detent torque even when the stator is not energized.
Fig. 5.62 : Basic concept of step rotation of stepper

Three-phase induction motor: This has a statoi with three windings mounted 120o art, each winding connected to one of the three lines of the supply fig. 5.59. Since the three phase reach their maximum current at different times, it can be considered that the magnetic field rotate the stator poles complete one rotation in one full cycle of the current.
Fig. 5.59 : Three Phase
advantage of self-starting. The direction of rotation of the motor can be changed by changing the direction of rotation of magnetic field by interchanging any two of the line connections. The speed of revolving of the magnetic field produced by primary currents is called the synchronous speed of the motor, and is given by N= 120f/p where f is the supply frequency and p is the number of poles. This revolving sweeps across the rotor conductors and thereby induces an emf in these conductors.
Synchronous motors : Synchronous motors has a rotor of permanent magnet or can Demagnetized by supplying d.c supply seperately. The magnetic field of the stator due to a.c supply rotates, and so the magnets of the rotor fig. 5.60. The rotor has two poles and the stator has two poles per phase. The magnetic field rotates through 360O in one cycle of supply and the frequency of rotation will be equal to frequency of supply current. They are used when a precise speed is desired. They are also not of self starting type and a seperate system has to be used for starting them. This gives constant speed from no load to full load. Electromagnetic power varies linearly with the voltage. They operate at higher efficiencies, especially in the low speed but it may fall out of synchronous and stop when over loaded. Advantages of a.c motor over d.c motors
Fig. 5.60 : Three phase two poles synchronous motor
a. Cost is less
b. More rugged
c. Reliable
d. Maintenance free.
Variable speed a.c motor
The disadvantage in a.c motor is the speed control being more complex than d.c motors and hence speed controlled d.c motors are much cheaper than speed controlled a.c motors. Speed of a.c motor depends on the frequency of the a.c supply and one method of controlling the speed is by controlling the frequency of the a.c supply. But the torque developed by a.c motor remains constant when the ratio of stator voltage to frequency is constant. When the frequency is varied for controlling the speed, the torque developed will also vary. To overcome this problem a.c supply is first rectified to d.c using a converter and then using an inverter the d.c again converted back to a.c, this inversion being at selected frequency of a.c. The other method is to convert a.c into a.c at the desired fequency using a cycloconverter without converting a.c to dc. Fig 5.61 shows the basic concept of variable speed a.c motor using a converter and an inverter.

This will take care of the forces acting on the coil to remain acting in the same direction and continue rotation. The direction of rotation of the rotor can also be reversed, by reversing either the field current or armature current depending on the configuration of the field coil and armature coil.
A.C Motors
Electric motors using A.C. supply are called A.C. motors. Classification of a.c motors Alternating current motors are broadly classified into two grouj
I. a. Single-phase a.c motors and
b. Poly-phase a.c motors
II a. Induction motors
b. Synchronous motors.
That is a.c motors can be single phase induction or synchronous motors or polyphase induction or synchronous motors.
Single phase motors are used for low-power requirement and poly phase for higher power requirement.
Induction motors are inexpensive than synchronous motors and are widely used.
Single phase induction motor
This consists of a single phase stator winding with a cage rotor represented schematically in fig. 5.58. The rotors are made up of either copper or aluminium bars that fit into slots in the end
Fig. : 5.58 : Single phase squired cage indication
rings to form a complete electrical circuit. Instead of being concentrated coil, the actual stator winding is distributed in slots in order to give an approximately sinusoidal distributed m.m.f (magneto motive force) in space. When an alternating current is passed through the stator windings, an alternating magnetic field is produced. As a result of electromagnetic induction, emfs are induced in the conductors of the rotor and current flows in the rotor. Such a motor inherently has no starting torque.
Drawbacks of single phase induction motor
Single phase induction motors suffers from several drawbacks. They are,
Low over load capacity
Low efficiency
Low power factor
No self starting
The frequency of the a.c supply determines the speed of the motor. For a two-pole single phase motor supplied with constant frequency supply will alternate the magnetic field with this frequency. This speed of rotation of magnetic field is called synchronous speed. The rotor rotates at slower speed than the rotating stator fields (this is called slip) making the induction impossible. Hence the term asynchronous. Because of this asynchronous motors are sometimes referred to as induction motors. Generally the slip is around 1 to 3 percent.
Three-phase induction motor
Poly-phase induction motor is, by very considerable margin the most widely used a.c motor,
Advantages of poly-phase motor
a. Low cost
b. Simple and extremely rugged construction
c. High efficiency
d. Reasonably good power factor
e. Low maintenance cost
f. Simple starting arrangement.

Advantages offrictionless guideways
a. High stiffness
b. Frictionless
c. No stick-slip
d. Large damping capability
e. Better heat dissipation and hence less thermal distortion
f. Longer life.Disadvantages
a. High cost
b. Leakage problems
c. Difficultly in assembling
guide way and the slide separated by a of high compressed air. These guide ways are also called Aero static guide ways. Because of thek low stiffness characteristic they are used only in positioning applications. Such as Co-ordinate measuring machine (CMM)
Motors
Motors are rotary actuators which make rotational movement when external energy is applied to it. If the external energy given is electrical energy then it is called electric motor. Electric motors are electromechanical devices which converts electrical energy into mechanical energy. Electric motors are the most common actuators used in majority of the mechanical system where motion and force are involved.
Electric motors can be classified based on,
a. its functionality such as torque motor, gear motor, servomotor etc.
b. the type of current used i.e., d.c motors and a.c motors.
The basic principles involved in the action of a motor are,
a. A force F is exerted on a conductor of length L carrying a current /, placed in a magnetic field of flux density B at right angles to the conductor. The force so exerted is given by F = B1L. Fig. 5.40.
DC MOTORS
Principle: A loop of coil carrying current free to rotate, when placed in a field of permanent magne; is acted upon by forces on its sides at right angles to the field, rotates by 90°. Iftherototiw were to be continued the direction of current flowing through the coil is to be reversed. Fig. 5.42. In conventional d.c motors, coils of wire aremounted in slots provided on a cylinder of magnetic material called the armature. The armature is mounted on bearings in a magnetic field produced by field poles. In the fig. 5.43 the magnetic field is produced by the current carried by the field coil. The end of each coil is connected to the next segment of the segmented ring called commutator which delivers current and controls its direction into the armature coil. Solid brushes provide stationary electrical contact to the moving commutator conducting segments. (Brushes in early motors consisted by bristles of copper wire flexed against the commutator and hence the term brush). Brushes are usually made out of conducting solid graphite which provide large contact area, spring loaded for ensuring continual contact and self lubricating. In the air gap between the rotor and the stator the magnetic fields interact. As the armature rotates, the commutator reverses the direction of current in each coil as it moves between the field poles.

LM guide boasts the following outstanding features.
a. Smooth movement with no clearances
b. High running precision with ease
c. High positioning accuracy
d. High rigidity in all directions
e. High permissible load rating
f. High long-term precision
g. High speed operation
c. High productivity
d. Substantial energy-savings
e. High efficiency in machine design
f. Easy maintenance
LM Guide with caged ball technology
In the conventional LM guide their existing contact between the balls (rolling elements) resulting in friction between balls which produce noise. Fig. 4.16.
The above drawback of conventional guide has been over come using caged ball technology. Caged ball technology eliminates contact between balls. This prevents friction between balls thereby ensuring low-noise, maintenance free and high speed operation for a long period of time.
Friction between balls
In the conventional LM guide, the rotary ball bearing of the LM part are not caged. Friction between balls caused loud noise, made high-speed rotation impossible and shortened the service life.
Later after 20 years of the above invention the caged ball design was developed for rotary ball bearings. The new design reduced the number of balls used while enabling high-speed rotation at low noise level and increasing the service life. This marked a major break through in the history of rotary ball bearings. Similarly the quality of needle bearings was significantly improved by the caged ball structure.
What happens in bearings that are not ball caged ? (Disadvantages of uncage ball design).
a. Balls contact one another at various points and rotate in opposite directions.
b. The sliding contact two adjacent balls occur at a speed twice the ball-spinning rate.
c. As the balls are metallic, they cause severe wear and load noise, resulting in short series life.
d. Normally, an oil film between the balls used as lubrication breaks under a bearing stress of 3 kg/mm2. Uncaged ball create point contact, resulting in infinite bearing stress, breakage of the oil film and sliding contact between balls.
Advantages of caged ball design
a. The contacts of the ball is over a wide area, hence oil film will not break.
b. The noise level is low.
c. The balls can rotate at high speed
d. Long service life.
The service life is prolonged (long service life) due to elimination of wear caused by friction between balls.
The lack of friction between balls results in reduced heat generation during high-speed rotation. Lack of friction between balls results in lack of ball-to-ball impact noise.
Even spacing of balls enables them to move smoothly.
The retaining of lubrication oil between balls ensures longer service life.
These type of antifriction linear motion bearing can reduce stick- slip to a very great extent.
Advantages of antifriction guideways
a. Reduced stick-slip motion of slides
b. Low static and Kinetic frictional resistance
c. High durability
d. High accuracy of movement of slides
e. High load coming capacity because of reduced friction.
f. High traverse speed.
g. East of assembly.
h. Operation without external hydrodynamic lubrication.
Disadvantage
a. Low damping Capacity
b. Very expensive.
Use of ball and rollers requires highly finished and hardened guiding surface because contact iscurved line or point, where the waviness of the surface impairs the accuracy of the motion. To combine the advantages of both sliding (as regards to the accuracy of guided motion) and rolling
tools.
Frictionless guide ways: This is featured by solidless contact between the surfaces of the guide ways and slides. In the case of friction and antifriction guide ways there exists physical contact of metals or solids which are proved to wear developing friction. This necessitate replacement of the guide ways and slide after a long usage and another major disadvantage of antifriction guide ways is its low damping capacity. The above demerits of antifriction guide ways can be over come by frictionless guide ways.
Frictionless guide ways do not have any solid or metal contact between the guide ways and the slide and the two are separated by a thin film of fluid. Frictionless guideways are of two types depending on the fluid employed to separate the guide ways and the slide. They are.
a. Hydrostatic guide ways
b. Pneumatic guide ways (Aero static guide ways)
Hydrostatic guide ways Hydrostatic guide ways are those wherein the surfaces of the guide and the slide are separated by a film of oil supplied under a pressure. These type of guide ways are increasingly finding its application is precision machine tools. Friction and stick -slip are completely eliminated. The clearance between the two surface is maintained between 15 to 25 microns. Fig 4.19 shows the principle of hydrostatic guide ways. A high degree of dynamic stiffness and damping can be achieved with these types of guide ways contributing to good machining capabilities.

wear due to usage and manufacturing imperfections. It is highly uneconomical to replace the whole guideway. Instead clearance between mating surfaces may be controlled periodically by means of gibs or strip lining.
These guide ways cannot be used directly in CNC machines, as the demand is for better characteristics because of rapid movements of slides and higher utilization of machine. The solution to this is “antifriction and frictionless guide ways”.
Stick - Slip Phenomenon.
In the case of friction guide ways before the commencement of motion of the slide there exist static friction between the guide ways and the slide, and once the motion has commenced it will be Kinetic friction which is a function of velocity of the slide. The static friction which is high acts on the drive mechanism such as screw and deform it elastically. This results in storing of energy in the screw along with the applied force and cause the slide to slip or move with a jerk. As more and more force in applied to overcome static friction and when the force applied exceeds the static friction, the slider tends to move faster than intended leading to improper positioning of the slide and consequently resulting in jerky motion. This is known as Stick - Slip phenomenon. Fig 4.7 shows graphically the relationship between coefficient of friction and velocity of the slide for friction guide ways.
constant co-efficient of friction is maintained between moving surfaces is contact. This can be achieved by fixing strips of materials having low and constant coefficient of friction, such as poly ten a fluro ethylene (PTEF) or turcite liners on the guide way surfaces. Turcite is a special type of plastic embedded with graphite particles. These graphite particles also act as solid lubricant.
Antifriction guide ways and slides
Even though friction can be minimized in friction guide ways still they are not used in CNC machines. Antifriction guide ways a special type with very low co-efficient of friction are used are in CNC machines. In this case the surface contacts between the guide ways and the slide is prevented by using an intermediate rolling elements such as spherical ball or cylindrical roller between them. These intermediate elements make point contact or line contact (Point contact by spherical ball and line contact by cylindrical roller between the surfaces of the guide ways and the slide ways resulting in considerable reduction in friction. Fig 4.8 illustrates the basic concept of antifriction guide ways. These guide ways ensures precision movements of the slide at uniform speed and have long service life.

These guide ways are employed in CNC machines for the following reasons.
a. Reduced friction, heat generation and wear.
b. Improve smoothness of movement of slides
c. Uniform speed of motion.
d. Long service life.
There are several types of antifriction guide ways that are employed. The most common of them used in CNC machines are,
a. Linear bearing with balls
b. Linear bearing with rollers.
Recirculating balls bearing
In the case of conventional ball and roller bearings, the rolling elements are confined to their pockets, provided in between the inner and outer races as shows in fig 4.9. These are called bush or non-recirculating ball and roller bearings. These functions properly when they are used in the horizontal plane as in the case of vertical spindles of machine tool, where in the load acting on the rolling elements will be uniform. But when used in any other plane as in the case of horizontal spindle of machine tool, there is every possibility of nonuniform wear of the pockets and the rolling elements. This reduces the performance of the bearing. The above problem can be avoided by recirculating the rolling elements, so that all the rolling elements are uniformly loaded. Fig 4.10 illustrates the concept of recirculation of rolling element. The balls in addition to revolving about its own axis also revolve around in the continued race similar to planets. The antifriction bearings listed earlier make use of this concept.

a. Friction guide ways
b. Antifriction guide ways
c. Frictionless guide ways.
Friction of Guideways
Friction guide ways are those wherein there exists surface contacts between the guide ways and the slide. Such guide ways finds its application in conventional machine tools because of their low manufacturing cost and good damping properties. These guide ways have varying coefficient of friction and operate under condition of sliding friction. In such guide ways the co-efficient of friction varies with sliding velocity.
There are four distinct types of friction guide ways based on their cross section. They are
a) Vee guide ways
i. With apex upwards
ii. With apex down wards (Inverted vee)
b) Flat guide ways
c) Dovetail guide ways
d) Cylindrical guide ways, and combination of these.
All these have distinct merits and demerits over each other. Some time it becomes desirable to use a combination of these guide ways.

Vee Guideways
The most widely used guideway on machine tools is Vee or Inverted Vee type as shown, in fig. 4.2, particularly on lathe beds. The Vee type guideways are advantageous because of the self adjustment action due to the weight of the guided parts and therefore the possibility of any play is eliminated. With Vee guides having its apex upwards there is no chip falling or chip accumulation. But lubrication in such cases is difficult. Such guideways donot check the over turning tendency of slides or guided parts. Vee type guideways wears away rapidly due to lack of bearing surface and is difficult to manufacture.
Cylindrical Guideways
Cylindrical guideways offer restraint free guidance fig. 4.5. This fulfills the conditions of kinetic principles being fully, constrained. However high accuracy of manufacturing is essential and hence are expensive. Cylindrical guideways are very efficient for short traverse and light loads. It cannot be used for long traverse and heavy loads because the guideways may sag or bend in the centre of the span under the load.
Dovetail Guideways
Dovetail guideways are preferred when both horizontal and vertical location of the moving parts is considered essential. The guideways have large load carrying capacity and tend to check the overturning tendency under eccentric loading. Fig. 4.4.
In the case of inverted Vee type guideways there is possibility of falling and accumulation of chip, and lubrication is easier.
Flat Guideways
Flat guideways are easy to manufacture and offer a large bearing area, than other guideways and hence suitable for heavy load transmission. Although Vee type have certain advantages, it is the flat or the dovetail type that are used in CNC machine tools. However chip accumulation and lubrication problems are serious. In addition flat guide ways do not wear uniformly. Jibs are used to ensure accurate fitting of the slide on the flat surface. Fig.4.3.
Fig. 4.3 : Flat type guideways

A CNC machine is a mechatronics system since the machine tool which is a mechanical system is incorporated or integrated with electronic controls for its different drives and computer system for interfacing the software with the mechanical and electronic system. Hardware or electronic circuits controls the motions of various drives.
The basic design of conventional machine tools are not suitable for CNC machines because CNC machines have to meet additional requirements.
a. The manual handwheel controls of conventional machine tools are replaced by axis drive motors.
b. To minimize the size of these motors the friction between sliding surfaces have to beconsiderable reduced or prevented if possible.
c. Higher cutting speeds, feeds and improved tooling system induces high multi directional forces which demands for proper machine structure.
d. Much of the time in CNC machines are spent in cutting operations, allowing very little time for setting and change over of jobs.
e. This means high metal removal rate and faster wear of guide ways, lead screws, gears etc.
f. This calls for an efficient system for swarf removal from the machining place and lastly the safety of the operator.
Element of CNC Machine
In order to cater for the above requirements special consideration should be exercised while designing the different elements of the CNC machine. The important elements of a CNC machine are,
a. Machine Structure
b. Guide ways / Slide ways
c. Spindle Mounting
d. Drive Units (Elements of transmission and positioning of slides)
e. Tool and work holding devices
f. Measuring systems
g. Swarf removal
h. Safety Devices.

Guide Ways
Guide ways or slide ways are provided on machine structure to provide
a Movement of slides which carry the tool, the job or the tool post
b To maintain proper alignment of sliding or guided part at all relative positions.
c To absorb all static and dynamic loads.
Guide ways may be an integral part of the machine structure or may be mounted separately on the structure. These guide ways may be horizontal, vertical or inclined, but vertical and inclined guide ways are preferred so that the chips produced during cutting operation do not get collected on the guide ways.
The dimensional accuracy, shape and surface finish of the component or part produced depend on the accuracy of the movement of the slide, geometric (shape) and kinetic accuracy of the guide ways. The geometric relationship of the slide and the guide ways with reference to the base of the machine determines the geometric accuracy of the machine. The kinetic accuracy of the guide ways depends on the straightness, flatness and parallel. Error in any of the above leads to kinetic inaccuracy. Kinetic inaccuracies may result in variety of tracking errors such as pitch, yaw and roll of the slide that are difficult to measure and correct. Errors may also arise due to wear in the guide ways and slides over a period of usage resulting in inaccurate movement and positioning of the slide.
Desired characteristics of guide ways
a. Should possess large stiffness to give exact alignment for guided parts in all positions and also under the effect of operational forces.
b. Minimum wear and provision for compensation of wear developed after usage.
c. Ease of assembly and economy i n manufacturing.
d. Provision for adjustment of play.
e. Geometric and kinetic accuracy.
f. High stiffness and less deformation under the influence of cutting forces.
g. 'Freedom from unnecessary restraint.
Factors influencing the design of guide ways
a. Stiffness and alignment of guided parts
b. High wear resistance and provision for compensation of worn out parts.
c. Effective lubrication and efficient lubricating system.
d. Effective coolant and efficient coolant system
e. Minimum or no chip getting entrapped.
f. Ease of assembly and economy of manufacture
g. Freedom from unnecessary restraint.
h. Velocity of slide.
i. Provision of adjustment of play
j. Protection against swarf and damage.
k. Protective guards to safe guard the guide ways against accidental damages (Mechanical abuse).
The above factors may vary in importance depending upon the particular application and hence selection of type of guide ways and their shape are quite critical in some applications. To import uniform frictional force in the guide ways the driving mechanism should be properly and correctly located relative to the forces of the guide ways.
Types of guide ways.
Guide ways are broadly classified into three types. They are

Engine management system is used for managing the ignition and airfuel requirements of an engine. In the case of a four stroke multicyUnder petrol engine, each cylinder has a piston performing all the four stroke (suction, compression, working or expansion and exhaust strokes) and the piston rod of each piston connected to a common crankshaft, and their power stroke at different times resulting in continuous power for rotation of the crankshaft.
The power and speed of an engine are functions of ignition timing and air fuel mixture. Henc, by controlling the the ignition timing and air fuel mixture it is possible to control the speed and power of the engine. In modern cars the ignition timing, opening and closing of valves at appropriate time, quality of air fuel mixture are controlled by microprocessor with the help of sensors. Fig. 1.16 illustrates the basic concept of engine management
In modern washing machine mechanical system is replaced by digital device i.e., a micro controller and the sequence of instruction i.e. program embedded in the microcontroller. The amount of detergent, amount of water, pH value are all sensed by the sensor and these sensed quantities or signals are input to the microcontroller. Based on the input and the software embedded, the corresponding output of the micro controller to carry out the different sequence of operations. The sequence of contrail can be varied by varying the software embedded at the manufacturing level of the washing machine. Figure 1.15 illustrates the block diagram of a microcontrolled based automatic washing machine.

For ignition timing the crankshaft drives a distributor which makes electrical contacts for each spark plug in turn a timing wheel. This timing wheel generates pulses which are input to the microprocessor. The microprocessor as per the program adjusts the timing at which high voltage pulses are sent to the distributor so that spark occurs at the right time resulting in complete combustion of the fuel. The quantity of air-fuel mixture entering the cylinder during suction stroke is again controlled by the microprocessor by varying the time for which the solenoid is activated to open the intake and the throttle position. The quantity of fuel injected into the air stream (to form air fuel mixture) is sensed by a sensor of the mass flow rate or calculated from other method, and then input to the microprocessor which in turn gives an output to control the fuel injection valve. This is only a very brief description of the engine management system using microprocessor.

ELEMENTS OF CNC MACHINE

INTRODUCTION
The primary function of any machine tool is to impart the required shape and dimensions to a work piece with the desired accuracy by removing excess material from the work piece in the from of chips or particles.
A computerized or computer numerical control (CNC) is a control system that utilizes dedicated, program stored computer or microcontroller to perform some or all the basic numerical control functions. A machine tool incorporating such a control system is called CNC machine. Fig. 4.1

Engine management system is used for managing the ignition and airfuel requirements of an engine. In the case of a four stroke multicyUnder petrol engine, each cylinder has a piston performing all the four stroke (suction, compression, working or expansion and exhaust strokes) and the piston rod of each piston connected to a common crankshaft, and their power stroke at different times resulting in continuous power for rotation of the crankshaft.
The power and speed of an engine are functions of ignition timing and air fuel mixture. Henc, by controlling the the ignition timing and air fuel mixture it is possible to control the speed and power of the engine. In modern cars the ignition timing, opening and closing of valves at appropriate time, quality of air fuel mixture are controlled by microprocessor with the help of sensors. Fig. 1.16 illustrates the basic concept of engine management
In modern washing machine mechanical system is replaced by digital device i.e., a micro controller and the sequence of instruction i.e. program embedded in the microcontroller. The amount of detergent, amount of water, pH value are all sensed by the sensor and these sensed quantities or signals are input to the microcontroller. Based on the input and the software embedded, the corresponding output of the micro controller to carry out the different sequence of operations. The sequence of contrail can be varied by varying the software embedded at the manufacturing level of the washing machine. Figure 1.15 illustrates the block diagram of a microcontrolled based automatic washing machine.

Working: To take the photograph of an object with the help of the camera, the switch is pressed which activates the system. The range sensor, senses the distance of the object to be photographed and this data is input to the micro processor. The microprocessor in turn sends on output to motor drive to position the lens for focusing. The position of the lens is input to the micro processor. The light sensor sends the signal of light intensity on the object to the microprocessor. Based on this, signals are sent to control the duration of time the shutter have to be kept open. All these actions and reactions take place with in fraction of a second. Once the film has been exposed, the information is input to the microprocessor which gives output for driving the motor for advancing the film to drive and the camera is ready for the next exposure. Earlier cameras were adjusted for light, focusing and time or duration of operture opening based on the sensitivity of the film including winding all being carried out manually.
Digital cameras: Digital cameras are flooding the market, indicating an era of digital technology. In this case the image of the object taken by the cameras is converted to digital images and stored is memory housed in the camera. As many number of photographs can be shot depending on the memory size. The photos stored in the memory can be seen on the monitor of a computer system and selection can be made. With the help of a good printer and quality paper the photographs can be obtained. The memory chip can be used again and only thing is it is overwritten. Also the contents of the memory chip can be transferred and then printout of selected shot can be made at leisure. Handy cams of magnetic tape, and digital types with separate memory chip for still photographs are available in the market.
Automatic washing machine
This is a sequential controlled system wherein control is exercised based on event, or are time driven i.e., control action will be executed one after another operation. The operations to be carried out in a domestic washing machine are soaking, washing, rinsing and drying. Each of these operations involves number of steps. Soaking involves selection of correct quantity of detergent and water based on the type and amount of cloth. This requires opening of the valve to fill the machine drum to the required level and closing the valve once the required level of water has reached and rotating the drum one/two rotations in either direction for a pre-set amount of time during the soaking operation.
This is followed by washing which is a time event. Then the rinsing event which measures the pH value and compares it with the supply water. This event continues till the pH value of the water in the cloth and the supply water are equal. Finally the drying operation till the minimum percentage of moisture is retained in the cloth.
All these events were earlier controlled with the help of mechanical system which involved a set of cam-operated switches; the contour of the cam operating different switches being proportional to time. The sequence of instruction used was a function of the set of cams used.

Microprocessor based control system range from a small programmable controller to a microprocessor used to control an entire fractionating column in an oil refinery.
A few of the micro controller based applications have been discussed here. Microprocessors are now rapidly replacing mechanical cam-operated controllers and being used in general to carry out functions. The following examples illustrate the basic aspects of microprocessor-based system that can be used to control focusing and exposure, sequence of washing cycle, managing the ignition and fueling requirements in automatic cameras, automatic washing machine and engine management respectively.
Automatic camera
Modern cameras are fully automatic including focusing and exposure. Fig. 1.14 illustrates the basic elements of the control system for an automatic camera.
in improved reliability, maintainability, reduction is size of the control system and manufacturing cost. Some of the application areas of microprocessor and micro controller-based system include
a. automobile engines
b. industrial automations
c. web-based process monitoring and control application etc.
Data Ocquisition System converts the analog signal from various sensors to digital signals that can be processed by a microprocessor. A keyboard and display in the system allow the user to enter set point values which are stored in the memory and the feed back of the current values are the process variable are read into the memory. Relays, DAS, solenoid valves and other actuators are used to control the process variables using the program. Fig. 1.13 shows a block diagram of a microprocessor basec ontrol system.

feeling whether it is too warm or too cold as in the case of bathing we mix cold water or hot water to have the temperature of the bath being comfortable. In this case it is purely by sense of feeling.

In the case of refrigerator the desired chamber temperature is preset with the help of a thermostat. The actual temperature in the refrigerator cabinet is monitored and compared with the desired value. A switch closes to cause the refrigerant to flow into the coils when the actual temperature increases above the preset value. Heat is taken from the cabinet causing its temperature to fall. The reverse of this process takeplace when the temperature falls below the preset or desired value. That is the thermostat switch opens and cutoff the refrigerant flow into the coils. Only when there is deference in temperature between the preset and the desired value i.e., error the system will operate. That is the system is discontinuous. Opening of the refrigerator door, placing warm food etc., are external disturbances to the system.
Sequential controllers
In many situations necessity arises to control a cycle of operations in sequence i.e., to carry out the different operations in sequence. The sequences of steps may be time based or event driven. One such cycle of operations is washing of clothes, the sequences being, soaking, washing, rinsing and drying. These operations are carried out using washing machines incorporated with relays and cam operated switches to carryout the sequence of operation of the washing cycle. Such type of control system are now being replaced by microprocessor based control system; the sequence being controlled by a software embedded in it. Human operator has to only press a button to activate the system after the clothes have been put into the drum, of course with a provision for continuous supply of water.
Note: Without our knowledge we come across many open and closed loop control systems. But it is for the reader to identify them.
Advantages of Mechatronics
a. A Mechatronics product can be better than just sum of its parts.
b. Mechatronics products exhibit performance characteristics that were previously difficultto achieve without the synergistic combination.
c. The mechatronic approach results in greater productivity, higher quantity and productionreliability by the incorporation of intelligent, self correcting sensory and feed back systems.
d. The integration of sensors and control systems in a complex system reduces capital expenses.
e. Maintains high degree of flexibility
f. Higher percentage of machine utilization
g. Products produced are extremely attractive to the consumer in quality and cost effectiveness.
Disadvantages of Mechatronics
a. Expensive to incorporate to an existing (old) system.
b. Initial cost of the system will be high.
c. Knowledge of different engineering fields is necessary for design and implementation.
d. Each system will have its own specific problem and depends on the system used for theapplication and hence to be properly addressed.

Microprocessor based controllers
Simple control problems can be solved by electronic control system involving combination of sequential logic 1C circuits using hardwired connections. In the past most control applications were relay based with nearly a one -to-one input-output ratio. Control systems, controlling a of group of relays, were capable of controlling machine tools, conveyor systems and other systems such as motors, industrial vehicles etc, followed by Programmable Logic Controllers (PLC) based applications. With the advent of semiconductor technology a more complex situation with more variable to control in a more complex control sequence using a microprocessor and software to make the 'interconnections'.Microprocessor and micro controller-based control systems have become increasingly popular not only in mechatronics systems but in many industrial applications because of their versatility, functionality and high integration level. The number of discrete components get reduced, resulting

Disadvantage of Open-loop System
a. Inaccurate since there is no correction for ever.
b. Relatively slow in response to changes in demand, (because it has to be manual)
c. Time to time recalibration of the controller is necessary to the maintain the qualityand accuracy of the output.
d. The control depends on the human judgement which may be inaccurate and may not beefficient.
e. Lack optimization in control.

Closed-loop System
A system in which the input is dependent on the output, i.e. variation in the output influences the input by some means of controlling on the input is called a closed loop system.
A closed loop system is characterised by the presence of a feedback system. Feedback system permits the output to be compared with the reference input so that appropriate controlling action can be achieved. The main feature of a closed loop control system is the comparison of the actual value of the variable with the desired value of that variable and any difference between these two values (called error) causes action to be taken in such a manner as to eliminate this difference or make the error zero.
Elements of closed loop control system
The basic elements of a closed loop control systems are
a. Comparison element
b. Control unit
c. Correction unit
d. Process unit.
e. Feed back unit.

Figure 1.8 shows the basic elements of a closed loop system.
Fig. 1.8 : Basic elements of a closed loop control system
A segmented circle is used as a symbol in general, for an element at which signals are summed up.
Functions of the elements of a closed loop system
Comparison element: This unit compares the reference or required value with that of the measured value or feedback signal (signal which is output of feedback element) and produces an error signal.
error signal = Reference signal (Reference value) ± Measured value.
Control unit: Control unit analyses the error signal and decides what action is to be taken. The unit poduces a signal; may be to operate a switch or a valve or perhaps a signal to proportionally open or close a valve which depends on the size of the error. The manipulation of the control unit is such that the error will approach zero.
Correction unit: The modified signal from the control unit will be received by the correction unit which produces a change in the process to correct or change the controlled condition. Change in process may be, allowing more power to the room heater to increase the temperature or vice versa, varying the valve opening for allowing the variation of liquid flow to enter the process.
Process Unit: Process unit is the one which is being controlled. It could be the speed a motor, speed of a vehicle, central heating unit or a central air conditioner.
Examples
One of the best example of a closed loop system is human being. A. person wants to reach for an object. Position of the object is given as reference feed back signals and the eyes compares the actual position of the hands with reference to the position of the object. Error signal is given to the brain. Brain manipulates this error and gives signals to the hands. This process continues till the hand reaches the object. Fig. 1.9.

Speed Control of vehicle
The object is to maintain a constant speed of the vehicle immaterial of the gradient and the load. The driver observes the speedometer, and based on the speed shown by the speedometer he decides whether the fuel supply should be increased or decreased or change of gear is to made.
Here the speed shown on the speedometer is feedback. Feedback signals from the eye compares the desired speed in the memory of the driver. Error signals are given to the brain. Brain manipulates the error and gives signals to hand and legs. The hand changes the gear and in the process applies the clutch from the leg and increases the fuel supply if the speed is less than the desired speed, otherwise decreases the fuel supply. Changing of gear and increase or decrease of fuel supply, depends on whether it is an upward or downward gradient respectively. Fig. 1.10 shows the concept of speed control.
Water level control of overhead tanks
Fig. 1.11 shows the schematic diagram of a water level control. The level of the water is sensed by the float. The float has an electrical contactor which is positioned between fixed contactors. The inflow regulation valve is electrically operated. The electrical circuit of the system is closed when the float contactor touches fixed contactors and open when it is not making contact with the fixed contactor. When the level of water in the tank falls the float moves down and make contact with the fixed contactor and the circuit is closed and the pump is switched on. When the level of water rises the float moves up and breaks the contact with the fixed contactor and the circuit is opened and the pump is switched off, thereby the required level of water is maintained
Automatic piloting ofaircrafts
Modern aircrafts are fitted with automatic flight controllers to reduce the monotony of continuous controlling of aircrafts by pilots during long flights. After attaining steady flight conditions, the desired direction and attitude are set on the automatic flight controller. With the help of compass and altimeter (to measure direction and altitude) actual direction and altitude are continuously monitored and automatically compared with the preset values. Any changes in either direction or altitude due to external disturbances such as cross winds or updraft currents are controlled by actuating the appropriate flight control, there by preset or desired flight conditions are restored.
Room temperature controller (Manual)
In this case the required temperature (i.e., comfortable temperature) will be decided by the person in the room and thus is compared mentally based on this whether the room temperature is high or low, the person will operate the switch of the room heater till the desired temperature is achieved Fig. 1.12.

Disadvantage of Open-loop System
a. Inaccurate since there is no correction for ever.
b. Relatively slow in response to changes in demand, (because it has to be manual)
c. Time to time recalibration of the controller is necessary to the maintain the qualityand accuracy of the output.
d. The control depends on the human judgement which may be inaccurate and may not beefficient.
e. Lack optimization in control.

Closed-loop System
A system in which the input is dependent on the output, i.e. variation in the output influences the input by some means of controlling on the input is called a closed loop system.
A closed loop system is characterised by the presence of a feedback system. Feedback system permits the output to be compared with the reference input so that appropriate controlling action can be achieved. The main feature of a closed loop control system is the comparison of the actual value of the variable with the desired value of that variable and any difference between these two values (called error) causes action to be taken in such a manner as to eliminate this difference or make the error zero.
Elements of closed loop control system
The basic elements of a closed loop control systems are
a. Comparison element
b. Control unit
c. Correction unit
d. Process unit.
e. Feed back unit.

Figure 1.8 shows the basic elements of a closed loop system.
Fig. 1.8 : Basic elements of a closed loop control system
A segmented circle is used as a symbol in general, for an element at which signals are summed up.
Functions of the elements of a closed loop system
Comparison element: This unit compares the reference or required value with that of the measured value or feedback signal (signal which is output of feedback element) and produces an error signal.
error signal = Reference signal (Reference value) ± Measured value.
Control unit: Control unit analyses the error signal and decides what action is to be taken. The unit poduces a signal; may be to operate a switch or a valve or perhaps a signal to proportionally open or close a valve which depends on the size of the error. The manipulation of the control unit is such that the error will approach zero.
Correction unit: The modified signal from the control unit will be received by the correction unit which produces a change in the process to correct or change the controlled condition. Change in process may be, allowing more power to the room heater to increase the temperature or vice versa, varying the valve opening for allowing the variation of liquid flow to enter the process.
Process Unit: Process unit is the one which is being controlled. It could be the speed a motor, speed of a vehicle, central heating unit or a central air conditioner.
Examples
One of the best example of a closed loop system is human being. A. person wants to reach for an object. Position of the object is given as reference feed back signals and the eyes compares the actual position of the hands with reference to the position of the object. Error signal is given to the brain. Brain manipulates this error and gives signals to the hands. This process continues till the hand reaches the object. Fig. 1.9.

Speed Control of vehicle
The object is to maintain a constant speed of the vehicle immaterial of the gradient and the load. The driver observes the speedometer, and based on the speed shown by the speedometer he decides whether the fuel supply should be increased or decreased or change of gear is to made.
Here the speed shown on the speedometer is feedback. Feedback signals from the eye compares the desired speed in the memory of the driver. Error signals are given to the brain. Brain manipulates the error and gives signals to hand and legs. The hand changes the gear and in the process applies the clutch from the leg and increases the fuel supply if the speed is less than the desired speed, otherwise decreases the fuel supply. Changing of gear and increase or decrease of fuel supply, depends on whether it is an upward or downward gradient respectively. Fig. 1.10 shows the concept of speed control.
Water level control of overhead tanks
Fig. 1.11 shows the schematic diagram of a water level control. The level of the water is sensed by the float. The float has an electrical contactor which is positioned between fixed contactors. The inflow regulation valve is electrically operated. The electrical circuit of the system is closed when the float contactor touches fixed contactors and open when it is not making contact with the fixed contactor. When the level of water in the tank falls the float moves down and make contact with the fixed contactor and the circuit is closed and the pump is switched on. When the level of water rises the float moves up and breaks the contact with the fixed contactor and the circuit is opened and the pump is switched off, thereby the required level of water is maintained

Disadvantage of Open-loop System
a. Inaccurate since there is no correction for ever.
b. Relatively slow in response to changes in demand, (because it has to be manual)
c. Time to time recalibration of the controller is necessary to the maintain the qualityand accuracy of the output.
d. The control depends on the human judgement which may be inaccurate and may not beefficient.
e. Lack optimization in control.

Closed-loop System
A system in which the input is dependent on the output, i.e. variation in the output influences the input by some means of controlling on the input is called a closed loop system.
A closed loop system is characterised by the presence of a feedback system. Feedback system permits the output to be compared with the reference input so that appropriate controlling action can be achieved. The main feature of a closed loop control system is the comparison of the actual value of the variable with the desired value of that variable and any difference between these two values (called error) causes action to be taken in such a manner as to eliminate this difference or make the error zero.
Elements of closed loop control system
The basic elements of a closed loop control systems are
a. Comparison element
b. Control unit
c. Correction unit
d. Process unit.
e. Feed back unit.

Figure 1.8 shows the basic elements of a closed loop system.
Fig. 1.8 : Basic elements of a closed loop control system
A segmented circle is used as a symbol in general, for an element at which signals are summed up.
Functions of the elements of a closed loop system
Comparison element: This unit compares the reference or required value with that of the measured value or feedback signal (signal which is output of feedback element) and produces an error signal.
error signal = Reference signal (Reference value) ± Measured value.
Control unit: Control unit analyses the error signal and decides what action is to be taken. The unit poduces a signal; may be to operate a switch or a valve or perhaps a signal to proportionally open or close a valve which depends on the size of the error. The manipulation of the control unit is such that the error will approach zero.
Correction unit: The modified signal from the control unit will be received by the correction unit which produces a change in the process to correct or change the controlled condition. Change in process may be, allowing more power to the room heater to increase the temperature or vice versa, varying the valve opening for allowing the variation of liquid flow to enter the process.
Process Unit: Process unit is the one which is being controlled. It could be the speed a motor, speed of a vehicle, central heating unit or a central air conditioner.
Examples
One of the best example of a closed loop system is human being. A. person wants to reach for an object. Position of the object is given as reference feed back signals and the eyes compares the actual position of the hands with reference to the position of the object. Error signal is given to the brain. Brain manipulates this error and gives signals to the hands. This process continues till the hand reaches the object. Fig. 1.9.

CONTROL SYSTEM
Control: The word control means regulate, manipulate, command or adjust. Let us consider the following examples:
A container is to be filled with water from a tap. Once the water fills the container the valve is closed (that is spilling of water is avoided) by observation from a human being who senses the filling and based on the observation closes the valve.
The driver applies the brake for the vehicle when he observes red traffic light. The traffic personnel regulate the traffic in order to maintain smooth flow of traffic.
In all the above cases, the human senses the requirement or necessity and based on it he or she acts, controls or regulates the system.
The temperature of our body is maintained constant immaterial of whether it i s summer or winter unless we are unwell.
It is impossible to control earth quakes, thunder, intensity of sun's heat etc., by human being.
Definition of control system
A group of devices or units or elements which maintain the required output based on the preset or predefined level or quantity by controlling or manipulating the parameters responsible for the output constitutes a control system. Generally the output of a measurement system will be the input to the control system. Fig. 1.5 illustrates a few simple examples of control system.
Si milarly the speed of a motor depends on the power supplied to the motor. In an open loop system the speed of the shaft rotation is solely determined by the position of speed selection knob. Any changes on the shaft load will result in change in speed and the change in speed will not be compensated for maintaining a constant speed. Fig. 1.7.
Advantages of Open-loop System
a. Relatively simple
b. Low cost
c. Good reliability
d. Easy maintainability
e. Inherently stable
power. The amount of power that can be input to the heater is say 1 kW or 2 kW. If a person just switch on the 1 kW position of the switch, the room will heatup and reach a particular temperature. If there are any changes in the condition such as windows being opened, then there is no heat adjustment to compensate for this variation. There is no information fedback to the heating system. Fig. 1.7(a).
Classification of Control System:
Control systems are broadly classified into two types. They are
a. Open loop control system, b. Closed loop control system (Feed back control system).
Open loop control system :
A control system in which the output is dependent on the input, but input or controlling action is independent of output or change in output, is called an open loop control system.
Examples:
A switch is used to off or on an electric lamp. This is an open-loop system. Fig. 1.6.

Measurement system: A group of elements forming a system to carry out the act of measurement is called measurement system.
General elements of a measurement system: Generally a measurement system comprises of these basic elements. They are;
a. Sensor/Transducer b. Signal conditioner c. Display or readout device
In addition to this electrical power supply depending on the system. Fig. 1.1 shows a block diagram of a generalised measurement system and its elements.
Functions of elements of a measurement system
Transducer: Transducer is an element or a device which converts or transforms or transduces
the measurand into some other form generally electrical form. Fig. 1.3 gives basic concept of
transducer.
In the measurement of temperature using a thermocouple, the input to the thermocouple is heat, which the thermocouple transforms in to an em/proportional to the heat. Here thermocouple is a transducer.
Similarly in the measurement of pressure of a fluid using Bourdon pressure gauge, the input is pressure and the bourdon tube is a transducer, which gets displaced. This displacement being proportional to the pressure is displayed on the gauge.
Signal conditioner: A device connected next to the transducer or which receives the output signals of the transducer and converts it into suitable, usable, measurable level of signals. In the case of measurement of temperature using a thermocouple the output of the thermocouple is an electrical quantity of magnitude of say some milli-volts and to display or use this further it has to be amplified to the required level using an amplifier. Here amplifier is a signal conditioner.
Signal conditioner can vary from a simple network of resistance or network of matching impendence to complex multistage amplifiers with detectors, demodulators and filters. Signal conditioners are also termed as signal modifiers or signal processors. The output of the signal conditioner may be either analog or digital quantity.
Display unit: This unit displays the output of the signal conditioner and this display will be the quantitative form of the measurand. Display unit may be either of analog type (the simplest from being a panel meter with a pointer moving across a calibrated scale) or of a digital type. With the development of Computer technology analog signals are invariably
converted into digital form with the help of analog digital converter (ADC) and the measured quantities are displayed in derived units / engineering units on a digital panel. Fig. 1.4 shows the principle of measurement system and digital display.

Measurement system
A system is may be defined as an orderly combination or arrangement of elements, devices, components etc into the single unit to carry out certain well defined function or it is the methodical arrangement of elements, devices, components, etc according to some rational principles.
The combination of physical objects such as machine parts, spring, vacuum tubes, transistors etc. is reformed to as a physical system in contrast to nervous system of our-body or any living being. Mechanical machineries, electrical machineries, TV, stereos are a few examples of physical system resulting from arrangement of component or parts following some rational principle.
Measurement: Measurement is the process of numerically quantifying a physical phenomenon such as dimension, speed, force, pressure, temperature etc so that the numerical quantity may be made use qV,er some constructive purpose. The quantity to be measured is called measured.

An overview of Mechatronics
The discipline of Mechatronics cannot be visualized as a signal entity. The definition of Mechatronics is elusive as it gives a broad meaning or concept of Mechatronics. The scope of Mechatronics is quite vast and the following activities can be enclosed is it.
a. Marketing
b. Manufacturing
c. Design
All of the above activities may not have direct impact on the field of Mechatronics.
Marketing as we all know is to identify user needs by surveying, analysing the data and finally the product specification for customer satisfaction.
Design concept is not limited only to dimensions, loads, materials, quality etc., but also from the aesthetic, comfort to use, cost, reliability, service etc. Many of the domestic appliances are designed from aesthetic point of view and some from the comfort point of view. Remote controlled gadgets such as TV, VCR, DVD players, automatic washing machines, remote controlled locking and unlocking system of automobile doors etc are designs from the comfort point of view and all these are mechatronic systems.
Design of mechatronics system
As far as the design of Machatronic systems is concerned the emphasis is more on understanding the fundamentals aspects of sensors, actuators, controls and integration methods, irrespective of the structure and implementation. The core of Mechatronics system broadly incorporates mechanical, electrical, electronics, information and control system engineering.
Mechanical engineering is quite a vast field. But as far as Mechatronics is concerned, actuation, modeling and mechanism are more important.
Electrical Engineering in Mechantronics is majority concerned with electrical actuators such as motors.
Electronic involves manipulation of electrical current and voltage using various components. These components are connected together to form circuit for controlling mechatronics systems. Electronic circuits range from simple load resistors to CPU and ASIC which contains millions of transistors.
Various control systems are adopted depending on the sophistication requirement.
Information systems are genetic and play an important role that significantly enhance the probability at all levels of control system

Evolution of Mechatronics
"Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent control algorithms in the design and manufacture of product and process."
Recently technology sectors all over the world have identified the importance of Mechatronics discipline for the product design. The concept was originated by the Japanese technocrats such as control system integrators, consumer electronics manufacturers researches etc. Later Scandinavian, American, European engineers experienced the significance and applicability in the design of electro mechanical system and also in other notable fields of applications. Now the concept of Mechatronics based design exists in areas of consumer products such as washing machines, cameras, automatic cash machines, robots, printing, light and heavy automobile engines, air crafts engines, industrial machines, agricultural equipment etc. The knowledge of Mechatronics is of prime importance to engineers of all fields.
As evolution process exits in all aspects of life; so also in Mechatronics. The technology has evolved through several stages that are termed as levels. The evolution levels of Mechatronics are
a. primary level Mechatronics
b. secondary level Mechatronics
c. tertiary level Mechatronics (third)
d. quaternary level Mechatronics (fourth)
In the early days Mechatronics products were at primary level containing I/O devices such as sensors, and actuators that integrated electrical signals with mechanical action at the basic control level. Electrically controlled fluid valves and relays are examples of primary level Mechatronics.
The secondary level Mechatronics integrates microelectronics into electrically controlled devices. Sometimes these products are stand alone ones. Example cassette player.
Third level Mechatronics incorporates advanced feed back functions into control strategy thereby enhancing the quality is terms of sophistication. Mechatronics system at this level is called smart system. The control strategy includes microelectronics, microprocessor and other 'Application Specific Integrated Circuits' (ASIC), Control of electrical motor used to actuate industrial robots, hard disk, CD drives, automatic washing machines are typical examples of third level Mechatronics.
The fourth level incorporates intelligent control in Mechatronics system. This level attempts to improve smartness a step ahead by introducing intelligence and Fault Detection and Isolation (FDI) capability systems. Artificial neural network and Fuzzy logic try to capture some of the intellectual capabilities of the intelligence

Origins of Mechatronics
The field of Mechatronics received the international recognition only in the last few years. The field has been driven by rapid progress in the field of microelectronics, where solid state microprocessor and memory have revolutionized many aspects of instrumentation and control and have facilitated exponential growth in data processing and communication.
The word Mechatronics was coined by Japanese is the late 1970 to describe the philosophy adopted in the design of subsystem of electromechanical systems. There have been major advances in technology and method in those early days and these were available to manufacturing sectors. Although Mechatronics is relatively a new term when compared to many other fields of engineering, it now appears to be firmly established. The term has been freely used by individuals, universities, industries all around the world. At research and development (R & D) level the following areas have been recognized under Mechatronics discipline.
a. Motion control
b. Actuators and sensors
c. Micro devices and optoelectronics
d. Robotics
e. Automotive systems
f. Modeling and design
g. System integration
h. Manufacturing
i. Vibration and noise control

1. Introduction to Mechatronics

INTRODUCTION
What is Mechatronics?
Mechatronics is the complete integration or adoption of electrical, electronics, computer technology information technology and control engineering with mechanical engineering.
Mechatronics plays a crucial a role in the design, manufacturing and maintenance of a wide range of engineering products and processes. As a consequence of this it has become necessary for engineers and technicians to have skills and knowledge that are not confined to a particular field or area of specilization.
Automation and control methods adopting integrated approach to technology has become relevant to industries, machineries and consumer engineering products. Mechatronics is an enabling discipline, has emerged to cater to the need of sophistication and flexibility in the system, and in fact has become a preferred choice for the current generation for real-time automation and control solutions in place of traditional systems. Most of the domestic equipments like washing machines, automatic cameras, digital cameras are a few examples of Mechatronics system which we use without bothering to know the technology adopted in it.
Productivity and quality level of many mechanical products and mechanical systems have considerably improved in the recent years, thanks to Mechatronics.
Multi disciplinary scenario
Multi disciplinary systems are not new; they have been successfully designed and used for many years. One of the most common is the electromechanical system which often uses a computer algorithm to modify the behavior of a mechanical system. Electronics are used to transduce information between the computer science and mechanical discipline.
Multi - disciplinary system employs a sequential design-by-discipline approach. For example in the design of electromechanical system three stages of designs were adopted. They are design of mechanical system, design of microelectronic system and control system. Each design application was after the completion of the previous one. The major draw back of design by discipline approach is fixing the design at various stages in the sequence which resulted in new constraints from the design upto that stage. These new constraints would make the other design to exhibit poor performance and fail to meet the new constraints. The error are costly to repair, major source of problem in the inherently complex nature of design. The solution to this is Mechatronics approach to system design which offers solution to the problems of sequential designing by applying concurrent engineering.