The Concept Of Fuzzy Logic Computer Science Essay

Chapter 1:


The construct of Fuzzy Logic ( FUZZY LOGIC ) was conceived by Lotfi Zadeh, a professor at the University of California at Berkley, and presented non as a control methodological analysis, but as a manner of treating informations by leting partial set rank instead than wrinkle fit rank or non-membership. This attack to put theory was non applied to command systems until the 70 ‘s due to deficient small-computer capableness prior to that clip. Professor Zadeh reasoned that people do non necessitate precise, numerical information input, and yet they are capable of extremely adaptative control.

If feedback accountants could be programmed to accept noisy, imprecise input, they would be much more effectual and possibly easier to implement. Unfortunately, U.S. makers have non been so speedy to encompass this engineering while the Europeans and Nipponese have been sharply constructing existent merchandises around it.

In this context, Fuzzy Logic is a problem-solving control system methodological analysis that lends itself to implementation in systems runing from simple, little, embedded micro-controllers to big, networked, multi-channel Personal computer or workstation-based informations acquisition and control systems.

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It can be implemented in hardware, package, or a combination of both. Fuzzy logic provides a simple manner to get at a definite decision based upon vague, equivocal, imprecise, noisy, or losing input information. Fuzzy logic ‘s attack to command jobs mime how a individual would do determinations, merely much faster.

Fuzzy logic incorporates a simple, rule-based IF X AND Y THEN Z attack to a work outing control job instead than trying to pattern a system mathematically.

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The fuzzed logic theoretical account is empirically-based, trusting on an operator ‘s experience instead than their proficient apprehension of the system. For illustration, instead than covering with temperature control in footings such as “ SP =500F ” , “ T & lt ; 1000F ” , or “ 210C & lt ; TEMP & lt ; 220C ” , footings like “ IF ( procedure is excessively cool ) AND ( procedure is acquiring colder ) THEN ( add heat to the procedure ) ” or “ IF ( procedure is excessively hot ) AND ( procedure is heating quickly ) THEN ( cool the procedure rapidly ) ” are used. These footings are imprecise and yet really descriptive of what must really go on. See what you do in the shower if the temperature is excessively cold: you will do the H2O comfy really rapidly with small problem. Fuzzy logic is capable of miming this type of behaviour but at really high rate.

Fuzzy logic requires some numerical parametric quantities in order to run such as what is considered important mistake and important rate-of-change-of-error, but exact values of these Numberss are normally non critical unless really antiphonal public presentation is required in which instance empirical tuning would find them. For illustration, a simple temperature control system could utilize a individual temperature feedback detector whose information is subtracted from the bid signal to calculate “ mistake ” and so time-differentiated to give the mistake incline or rate-of-change-of-error, afterlife called “ error-dot ” . Mistake might hold units of grades F and a little mistake considered to be 2F while a big mistake is 5F. The “ error-dot ” might so hold units of degs/min with a little error-dot being 5F/min and a big one being 15F/min. These values do n’t hold to be symmetrical and can be “ tweaked ” one time the system is runing in order to optimise public presentation. Generally, fuzzed logic is so forgiving that the system will likely work the first clip without any tweaking.

Fuzzy logic was conceived as a better method for screening and managing informations but has proven to be an first-class pick for many control system applications since it mimics human control logic. It can be built into anything from little, handheld merchandises to big computerized procedure control systems. It uses an imprecise but really descriptive linguistic communication to cover with input informations more like a human operator. It is really robust and forgiving of operator and informations input and frequently works when first implemented with small or no tuning.

Chapter 2:


There are infinite applications for fuzzed logic. In fact, some claim that fuzzed logic is the embracing theory over all types of logic. Some common applications of Fuzzy Logic are:

Bus Time Tables:

Bus agendas are formulated on information that does non stay changeless. They use fuzzed logic because it is impossible to give an exact reply to when the coach will be at a certain halt. Many unanticipated incidents can happen. There can be accidents, unnatural traffic backups, or the coach could interrupt down. An observant scheduler would take all these possibilities into history, and include them in a expression for calculating out the approximative agenda. It is that expression which imposes the indistinctness.

Predicting familial traits:

Familial traits are a fuzzed state of affairs for more than one ground. There is the fact that many traits ca n’t be linked to a individual cistron. So merely specific combinations of cistrons will make a given trait. Second, the dominant and recessionary cistrons that are often illustrated with Punnet squares are sets in fuzzed logic. The grade of rank in those sets is measured by the happening of a familial trait. In clear instances of dominant and recessionary cistrons, the possible grades in the sets are reasonably rigorous. Take, for case, oculus colour. Two brown-eyed parents produce three fair-haired kids. Sounds impossible, right? Brown is dominant, so each parent must hold the recessionary cistron within them. Their rank in the bluish oculus set must be little, but it is still at that place. So their kids have the potency for high rank in the bluish oculus set, so that trait really comes through. Harmonizing to the Punnet square, 25 % of their kids should hold bluish eyes, with the other 75 % holding brown. But in this state of affairs, 100 % of their kids have the recessionary colour. Was the married woman being unfaithful with that nice, fair-haired salesman? Probably non. It ‘s merely fuzzed logic at work.A

Temperature control ( heating/cooling ) :

The fast one in temperature control is to maintain the room at the same temperature systematically. Well, that seems pretty easy, right? But how much does a room have to chill off before the heat boots in once more? There must be some criterion, so the heat ( or air conditioning ) is n’t in a changeless province of turning on and off. Therein lays the fuzzed logic. The set is determined by what the temperature is really set to. Membership in that set weakens as the room temperature varies from the set temperature. Once rank weakens to a certain point, temperature control kicks in to acquire the room back to the temperature it should be.

Auto Focus on cameras:

Auto-focus cameras are a great revolution for those who spent old ages fighting with “ antique ” cameras. These cameras somehow figure out, based on battalions of inputs, what is meant to be the chief object of the exposure. It takes fuzzed logic to do these premises. Possibly the criterion is to concentrate on the object closest to the centre of the spectator. Maybe it focuses on the object closest to the camera. It is non a precise scientific discipline, and cameras err sporadically. This border of mistake is acceptable for the mean camera proprietor, whose chief use is for snapshots. However, the “ antique ” manual focal point cameras are preferred by most professional lensmans. For any mistakes in those exposures can non be attributed to a mechanical bug. The determination devising in concentrating a manual camera is fuzzy every bit good, but it is non controlled by a machine.

Antilock Braking System

The point of an ABS is to supervise the braking system on the vehicle and let go of the brakes merely before the wheels lock. A computing machine is involved in finding when the best clip to make this is. Two chief factors that go into finding this are the velocity of the auto when the brakes are applied, and how fast the brakes are depressed. Normally, the times you want the ABS to truly work are when you ‘re driving fast and sweep on the brakes. There is, of class, a border for mistake. It is the occupation of the ABS to be “ smart ” plenty to ne’er let the mistake goes past the point when the wheels will lock. ( In other words, it does n’t let the rank in the set to go excessively weak. )

Chapter 3:

Automations Systems:

3.1 Three types of Automations:

There are three basic discrepancies of machine-controlled railroad operation which apply irrespective of type of train used.

Where the trains travel automatically from station to station but a human train driver is ever present at the forepart of the train, with duty for door shutting, obstruction sensing on the path before the train and handling of exigency state of affairss.

In a driverless system where the trains runs automatically from station to station but a human Passenger Service Agent is ever present someplace in the train, with duty for door shutting and to reassure nervous riders that there is person ‘onboard ‘ who can take control in the ( improbable ) event of a failure or an exigency state of affairs.

In a wholly driverless system where the trains run automatically at all times, handle door shutting, obstruction sensing and exigency state of affairss, with the lone input from transport staff being from a distant control Centre.

Automation offers fiscal nest eggs in both energy and wear & A ; tear costs because trains are driven to an optimal specification – alternatively of harmonizing to each motorman ‘s ‘style ‘ . Automated trains respond more rapidly to alterations, such as drawing off instantly after a ruddy signal alterations to green – instead than the hold of even a 2nd or two which occurs with human drivers. Although holds of even one second may sound minimum, their cumulative effects, when translated to every train, negatively impinges upon the service frequence ( particularly during first-come-first-serve hours ) and hence reduces the figure of trains which can go along a subdivision of path.

Where trains are wholly unstaffed holding fewer people on the paysheet is financially advantages as staff represent a important portion of the cost of running a conveyance system. Some other advantages of non necessitating staff to be available to drive the trains include the ability to supply far more frequent services at quiet times ( such as eventides and weekends ) when rider degrees are lower and the gross earned would non warrant the costs of using a full complement of train drivers, and the ability of train operators to change the service frequence to run into a sudden unexpected demand

3.2 Automated ‘Driverless ‘ Metro Systems

Automated braking system has been used in the past before.It is still used in the present tube systems.

Automated systems are sometimes besides calledA people-moversA andA automated guided theodolites.

The termA people-moverA normally applies to smallA cabinA type conveyances such as are frequently found at airdromes. Few illustrations are theA Monorails, Maglev ‘s and ‘Cabin ‘ Conveyances.

The conveyances shown here are allA rapid transitA urbanA metroA ( orA mini-metro ) systems that serve full size towns and metropoliss. Some of these could besides be calledA automated guided theodolites, this being a term that refers to to the full automated, grade-separatedA§A conveyances that ( frequently ) use rubber-tyred vehicles which are self-guided – normally by horizontally running usher wheels.

The term ‘grade-separated ‘ agencies that they are ever kept separated from other conveyances and walkers – normally by being elevated above or below everything else, althoughA ifA theyA areA at land degree safety will order that they will necessitate to be fenced in so as to maintain all other types of conveyance and pedestrians off from their rights of manner. Which of class makes sense for an machine-controlled system which is non capable of chuck outing possible unexpected jeopardies along its right of manner?

3.2.1 Automated Train system in London:

After initial safety tests proved successful the first known automatically goaded rider train ran in 1963 between Stamford Brook and Ravenscourt Park on the London Underground District Line. Merely one specially modified train was involved, all other trains on this path continued to run in normal ‘human driven ‘ manner.

With farther tests between these two Stationss go oning to turn out successful, in 1964 full graduated table trails of automatically operated trains began on the Hainault – Woodford subdivision of the Central Line, which at that clip was operated as a little subdivision line shuttle service. Initially a dedicated fleet of four trains was involved, subsequently all the new trains destined for what was to go the first to the full automated line ( and is known as the Victoria Line ) were tested here excessively.

Because the shuttle service operated over the paths used by other trains so these tests efficaciously included shared operation of machine-controlled and human driven trains. The latter included Underground trains on both the Epping path every bit good as ( between Woodford and Grange Hill ) on peak-hour ‘extra ‘ workings going to & A ; from the depot located partway along the machine-controlled path. At this clip the mainline railroad ( British Railways ) still operated freight – and a few riders – services to Epping and Newbury Park via Woodford, so their steam ( Diesel in ulterior yearss ) trains besides travelled on subdivisions of path served by the machine-controlled trains.

British Railways operated trains here because when rider services along this subdivision of railroad were converted from steam to electric grip this was achieved by utilizing Underground trains to replace most of the rider services provided by the mainline railroad.

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Figure 3.a: One of the trains used on the Hainault – Woodford path to prove the machine-controlled rider train engineering.

3.2.2 Automated train System in Tokyo:

Tokyo ‘s first AGT system is theA New Transit Yurikamone, A which when it opened in 1995 was known as theA Tokyo Waterfront New Transit Waterfront Line.This line serves the unreal island of Odaiba which has become a popular amusement and leisure finish. Despite bear downing premium menus and there being cheaper ( subterraneous ) options the line is popular because being elevated it offers riders first-class skyline positions. Transporting over 100,000 riders per twenty-four hours it makes a net net income and will to the full pay off its building cost loans more rapidly than the originally anticipated 20 twelvemonth period. The line is 14.7kmA ( small over 9 stat mis ) A in length and serves 16 Stationss.

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Figure 3.b: The New Transit Yurikamone, Tokyo, Japan.

3.2.3 Automated Train System in Dubai:

On 9 September 2009, Dubai inaugurated its tube web, going the first urban tube web in the Gulf ‘s Arab provinces. It is hoped that the system will ease the day-to-day commute for 1000s of the emirate ‘s workers.

The driverless, to the full automated trains are to the full air-conditioned and designed to run into Dubai ‘s specific demands. Unusual for tube operation, the trains offer standard ‘silver ‘ category, a adult females and kids merely subdivision plus a excellent ‘gold ‘ subdivision ( a passenger car for VIPs ) . The five-car sets are about 75m long, siting about 400 riders but with standing room for many more. Numerous dual doors will let fast and smooth flows.

The automatic train control system will let headrooms of between 90 seconds and two proceedingss. In 2005 MHI contracted Alcatel ( now Alcatel-Lucent ) to provide the driverless train control system and a communications system for on-train picture surveillance, rider information, public reference and the integrated control Centre. Trains will be Wi-Fi enabled.

Busying 10,000mA? , the system ‘s control Centre is at Rashidiya terminal. The undertaking ‘s signaling system is traveling block and to the full automated with in-cab signaling.

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Figure 3.c: Dubai tube, Dubai, U.A.E

Chapter 4:


The Concept of Fuzzy Logic Control is really simple. There are three phases involved in fuzzed logic controls. These phases are input phase, a processing phase, and an end product phase. The input phase involves function of detector or other inputs, such as switches, thumbwheels, to their corresponding rank maps and truth values. In the processing phase each appropriate regulation is invoked and consequences for each regulation are generated, and so combine of the consequences of the regulations takes topographic point. In the concluding phase the combined consequence is converted back into a specific control end product value.

Membership maps form that is most normally used is triangular, although trapezoids and bell curves are besides used. By and large the form is non every bit of import as the figure of curves and where they are placed. From three to seven curves are largely required to cover the needful scope of an input value, or the “ existence of discourse ” in fuzzed slang.

A aggregation of logical regulations, consisting of IF-THEN parametric quantities, form the base of processing phase. The IF parametric quantity is referred to as “ ancestor ” and the THEN parametric quantity is called the “ consequent ” . Largely a common fuzzy control system has twelve or more regulations.

The regulations have rank maps specifying them. The rank maps can be modified by “ hedges ” that are like adjectives. Some of the common hedges include “ up to ” , “ far ” , “ over ” , “ about ” , “ really ” , “ lightly ” , “ extremely ” , and “ small ” . These operations by and large have precise definitions, although the definitions may alter well between different executions.

Operators like AND, OR, and NOT are used to unite ancestors, such as IF-THEN. A fuzzed regulation sets normally have several ancestors. Although once more the definitions may change harmonizing to its execution: AND, in one the definition, uses the minimal weight of all the ancestors, where as OR uses the maximal value. There is besides a NOT operator that subtracts a rank map from 1 to give the “ complementary ” map.

There are several different ways to specify the consequence of a regulation, but one of the most common and simplest is the “ max-min ” illation method, in which the end product rank map is given the truth value generated by the footing.

Rules can be solved in analogue in hardware, or consecutive in package. The consequences of all the regulations that have fired are “ defuzzified ” to a chip value by one of several methods.


A fuzzy logic based automatic braking system is proposed utilizing distance and comparative velocity detectors as inputs and brake-pressure as end product. Heuristic regulations have been developed and implemented. The accountant monitors the slowing rate of the vehicle to forestall tyre lock-up and the attendant loss of directional stableness. The system offers the flexibleness of puting the separation distance. Simulation of the accountant for driving into a stationary or traveling objects shows that the system is executing good. It besides uses an anti lock braking system to slow the vehicle and a throttle on-off accountant to speed up the vehicle and keep a fixed separation distance and thrust behind the object in a trailing manner.

Chapter 5:

Undertaking Details:

5.1 Automated Braking System in trains utilizing the Fuzzy Logic Controller:

This undertaking focuses a new manner of attack to happen the solution for the unreal intelligent braking system in train utilizing the fuzzed logic accountant. Here we are planing the fuzzed logic accountant utilizing fuzzed logic tool box in mat lab package. The fuzzed logic accountant is simulated utilizing Matlab-Simulink fuzzy logic tool chest. The chief map of the fuzzed logic accountant used here is to automatically halt the train in each station without any manual process of halting the train. The fuzzed logic accountant in train gets activated about 500 m from the station so that the train Michigans at the station swimmingly and automatically. The fuzzed accountant takes the determination with mention to the velocity and distance of the train.

By and large the design of automatic braking system becomes more complex but it can be made easier and flexible by utilizing fuzzed logic accountant. In order to acquire the dynamic end product the necessary inputs chosen for the fuzzed accountant are distance and velocity. The dynamic end product of the fuzzed accountant is interrupting power. Based on regulations of logic obtained from RTA metro unit, I have framed 4A-4 ( 16 ) regulations for fuzzed logic accountant. This attack uses the triangular and trapezoidal member maps. The consequences obtained from matlab simulation will clearly demo that the braking power end product is smooth and the train comes to a halt as the distance reduces down to zero.


The first measure in the design is to choose the figure of Stationss where the train Michigans.

The distances between the Stationss are calculated and stored. The fuzzed logic accountant is fed with the instantaneous values of velocity and distance. The accountant invariably compares the distance between the old and the following station to distance traveled by the train towards the nearing station, as and when the train is approximately 500m from the station the braking system in train gets activated.

See the instance where the train is at a distance of 200m from the station nearing it at a velocity 70 kmph. The numerical values therefore obtained are converted into fuzzed sets by fuzzification technique. The fuzzed set relevant to this input is,

Speeda†’ { really fast, 1 }

Distance a†’ { far, 0.8 }

After the fuzzification the corresponding regulations are fired for the instance considered, the regulation ‘If distance is ( FAR ) and velocity is ( VERY FAST ) so braking power is ( HEAVY ) ‘ is fired.

Then end product fuzzed value of the fuzzed sets is converted into numerical values by the defuzzification technique. This numerical value, which is the end product of the fuzzed logic accountant, is used to command the braking system of the train.

5.3 DESIGN Procedure:

The first measure in making a design is organizing rank maps for the inputs and end products. There are two inputs, Speed and Distance, and one end product Braking Power. The rank maps in this design consists both Triangular and Trapezoidal constituents.

The 2nd measure in the design process is rule formation utilizing the rank maps combined utilizing fuzzy operators, such as AND & A ; OR. This design has 4×4 ( 16 ) regulations which uses rank map of velocity, distance and braking power.

While planing this fuzzed logic accountant in mat lab FIS editor ( fuzzed logic tool chest ) , foremost the input and end product rank maps are designed and so the regulations are formed.

5.3.1 MEMBERSHIP FUNCTIONS ( Triangular and Trapezoidal ) :

Input signal

Speed Distance

1. Very slow 1.Very stopping point

2. Decelerate 2.Close

3. Fast 3.Far

4. Very fast 4.Very far

Membership Function of Distance:

Membership Function of Speed:

End product

Braking power

1. Very Light

2. Light

3. Heavy

4. Very Heavy

Membership Function of Braking Power:

5.3.2 Rules Formation:

1. If distance is ( VERY_CLOSE ) and velocity is ( VERY SLOW ) so braking is ( LIGHT )

2. If distance is ( VERY_CLOSE ) and velocity is ( SLOW ) so braking is ( HEAVY )

3. If distance is ( VERY_CLOSE ) and velocity is ( FAST ) so braking is ( VERY HEAVY )

4. If distance is ( VERY_CLOSE ) and velocity is ( VERY FAST ) so braking is ( LIGHT )

5. If distance is ( CLOSE ) and velocity is ( VERY SLOW ) so braking is ( LIGHT )

6. If distance is ( CLOSE ) and velocity is ( SLOW ) so braking is ( LIGHT )

7. If distance is ( CLOSE ) and velocity is ( FAST ) so braking is ( HEAVY )

8. If distance is ( CLOSE ) and velocity is ( VERY FAST ) so braking is ( VERY HEAVY )

9. If distance is ( FAR ) and velocity is ( VERY SLOW ) so braking is ( LIGHT )

10. If distance is ( FAR ) and velocity is ( SLOW ) so braking is ( VERY LIGHT )

11. If distance is ( FAR ) and velocity is ( FAST ) so braking is ( LIGHT )

12. If distance is ( FAR ) and velocity is ( VERY FAST ) so braking is ( HEAVY )

13. If distance is ( VERY FAR ) and velocity is ( VERY SLOW ) so braking is ( VERY LIGHT )

14. If distance is ( VERY FAR ) and velocity is ( SLOW ) so braking is ( VERY LIGHT )

15. If distance is ( VERY FAR ) and velocity is ( FAST ) so braking is ( LIGHT )

16. If distance is ( VERY FAR ) and velocity is ( VERY FAST ) so braking is ( LIGHT )


The concluding measure for the completion is the design of the simulation circuit of fuzzed logic accountant. The circuit takes the inputs in the signifier of velocity and distance and gives the end product in the signifier of interrupting power.

The simulation circuit is shown in Figure 5.4.a wherein the sum of braking power required for halting the train at the station is obtained from the inputs Distance and Speed.

Figure 5.4.a: Mat lab Simulation for Fuzzy Logic Controller

Figure 5.4.b shows the simulation circuit, which proves that the train is stops at the station.

Figure 5.4.b: Mat lab Simulation for Fuzzy Logic Controller


The regulations and rank maps that are formed for execution of the undertaking on mat lab platform. The rank maps and the regulations have been solved on paper to look into their rightness and efficiency.

The hereafter plans for the undertaking is to implement the simulation circuit it on mat lab utilizing Simulink fuzzed logic tool chest.

Find the consequences of the simulations and verify if the train would halt at the needed figure of Stationss automatically and swimmingly.

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The Concept Of Fuzzy Logic Computer Science Essay. (2020, Jun 02). Retrieved from

The Concept Of Fuzzy Logic Computer Science Essay

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