Technical Paper Title: FUZZY LOGIC AND ITS IMPORTANCE IN WHIZZY DEVICES
Authors: M.Krishna Meghana & V.Jhansi Rani, 3rd BTech, ECE
College: S.R Engineering College, Hasanparthy, Warangal
WHAT IS FUZZY LOGIC ?
Fuzzy logic is a form of multi-valued logic derived from fuzzy set theory to deal with reasoning that is approximate rather than precise. In contrast with “crisp logic”, where binary sets have binary logic.
Fuzzy logic variables may have a truth value that ranges between 0 and 1 and is not constrained to the two truth values of classic propositional logic.Furthermore, when linguistic variables are used, these degrees may be managed by specific functions.
From the definition of fuzzy logic..,as additional data are gathered,many systems are able to adjust the probability values assigned to different parameters.Because some such systems appear able to learn from their mistakes,they are often considered as acrude form of ‘ARTIFICIAL INTELLIGENCE’.Fuzzy logic systems acheivedcommercial applications in early 1990’s.advanced clothes washing machines,for example ,use fuzzy logic systems to detect and to adapt to patterns of water movement during a wash cycle,increasing efficiency and reducing water consumption.other applications include EXPERT SYSTEMS,self regulating industrial controls,and computerized speech..etc
HOW DOES IT DIFFER FROM PROBABILISTIC LOGIC
Fuzzy logic and probabilistic logic are mathematically similar – both have truth values ranging between 0 and 1 – but conceptually distinct, due to different interpretations.
Fuzzy logic corresponds to “degrees of truth”, while probabilistic logic corresponds to “probability, likelihood”; as these differ, fuzzy logic and probabilistic logic yield different models of the same real-world situations.
Both degrees of truth and probabilities range between 0 and 1 and hence may seem similar at first. For example, let a 100 ml glass contain 30 ml of water. Then we may consider two concepts: Empty and Full. The meaning of each of them can be represented by a certain fuzzy set. Then one might define the glass as being 0.7 empty and 0.3 full. Here the concept of emptiness would be subjective and thus would depend on the observer or designer. Another designer might equally well design a set membership function where the glass would be considered full for all values down to 50 ml. It is essential to realize that fuzzy logic uses truth degrees as a mathematical model of the vagueness phenomenon while probability is a mathematical model of randomness.
A probabilistic setting would first define a scalar variable for the fullness of the glass, and second, conditional distributions describing the probability that someone would call the glass full given a specific fullness level. This model, however, has no sense without accepting occurrence of some event, e.g. that after a few minutes, the glass will be half empty. The conditioning can be achieved by having a specific observer that randomly selects the label for the glass, a distribution over deterministic observers, or both.
Consequently, probability has nothing in common with fuzziness, these are simply different concepts which superficially seem similar because of using the same unit interval of real numbers [0,1]. Still, since theorems such as De Morgan’s have dual applicability and properties of random variables are analogous to properties of binary logic states, one can see where the confusion might arise.
HOW TO APPLY TRUTH VALUES.
A basic application might characterize subranges of a continuous variable. For instance, a temperature measurement for anti-lock brakes might have several separate membership functions defining particular temperature ranges needed to control the brakes properly. Each function maps the same temperature value to a truth value in the 0 to 1 range. These truth values can then be used to determine how the brakes should be controlled.
FUZZY LOGIC TEMPERATURE
In the above image, the meaning of the expressions cold, warm, and hot is represented by functions mapping a temperature scale. A point on that scale has three “truth values” — one for each of the three functions. The vertical line in the image represents a particular temperature that the three arrows (truth values) gauge. Since the red arrow points to zero, this temperature may be interpreted as “not hot”. The orange arrow (pointing at 0.2) may describe it as “slightly warm” and the blue arrow (pointing at 0.8) “fairly cold”.
While variables in mathematics usually take numerical values, in fuzzy logic applications, the non-numeric linguistic variables are often used to facilitate the expression of rules and facts.
A linguistic variable such as age may have a value such as young or its antonym old. However, the great utility of linguistic variables is that they can be modified via linguistic hedges applied to primary terms. The linguistic hedges can be associated with certain functions.
Types of fuzzy logics
Fuzzy logics can be classified into Propositional and predicate fuzzy logics.
Propositional fuzzy logic is of many types like…
Monoidal t-norm-based propositional fuzzy logic ,Basic propositional fuzzy logic,Łukasiewicz fuzzy logic ,Gödel fuzzy logic ,Product fuzzy logic ,Fuzzy logic with evaluated syntax.
PREDICATE FUZZY LOGIC
These extend the above-mentioned fuzzy logics by adding universal and existential quantifiers in a manner similar to the way that predicate logic is created from propositional logic. The semantics of the universal (resp. existential) quantifier in t-norm fuzzy logics is the infimum (resp. supremum) of the truth degrees of the instances of the quantified subformula.
Once fuzzy relations are defined, it is possible to develop fuzzy relational databases. The first fuzzy relational database, FRDB, appeared in Maria Zemankova’s dissertation. Later, some other models arose like the Buckles-Petry model, the Prade-Testemale Model, the Umano-Fukami model or the GEFRED model by J.M. Medina, M.A. Vila et al. In the context of fuzzy databases, some fuzzy querying languages have been defined, highlighting the SQLf by P. Bosc et al. and the FSQL by J. Galindo et al. These languages define some structures in order to include fuzzy aspects in the SQL statements, like fuzzy conditions, fuzzy comparators, fuzzy constants, fuzzy constraints, fuzzy thresholds, linguistic labels and so on.
As fuzzy logic can be applied to linguistic variables it can be used in many real world applications .some of such uses are its application in air conditioning,in devices used for photography,in digital image processing,dishwashers,elevators,some microcontrollers & microprocessors,language filters,in remote sensing,videogames and many home appliances
RELEVANCE OF FUZZY LOGIC IN AIR CONDITIONING
The task of conditioning the air in a particular place can be taken as a linguistic variable which varies not only in the domain of heat air and cold air but also regarding humidity control..,application of fuzzy logic here helps us in improving the efficiency of the system
Air conditioning is the dehumidification of indoor air for thermal comfort. In a broader sense, the term can refer to any form of cooling, heating, ventilation, or disinfection that modifies the condition of air.An air conditioner (often referred to as AC or air con.) is an appliance, system, or machine designed to stabilise the air temperature and humidity within an area , typically using a refrigeration cycle but sometimes using evaporation, commonly for comfort cooling in buildings and motor vehicles.
.Innovation in air conditioning technologies continues, with much recent emphasis placed on energy efficiency, and on improving indoor air quality. Reducing climate change impact is an important area of innovation, because in addition to greenhouse gas emissions associated with energy use, CFCs, HCFCs and HFCs are, themselves, potent greenhouse gases when leaked to the atmosphere. For example, R-22 (also known as HCFC-22) has a global warming potential about 1,800 times higher than CO2 As an alternative to conventional refrigerants, natural alternatives like CO2 have been proposed.
AIR CONDITIONING APPLICATIONS
Air conditioning engineers broadly divide air conditioning applications into comfort and process.
Comfort applications aim to provide a building indoor environment that remains relatively constant in a range preferred by humans despite changes in external weather conditions or in internal heat loads.
Process applications aim to provide a suitable environment for a process being carried out, regardless of internal heat and humidity loads and external weather conditions. Although often in the comfort range, it is the needs of the process that determine conditions, not human preference.
In both comfort and process applications the objective may be to not only control temperature, but also humidity, air quality and air movement from space to space.
Refrigeration air conditioning equipment usually reduces the humidity of the air processed by the system. The relatively cold (below the dewpoint) evaporator coil condenses water vapor from the processed air, (much like an ice-cold drink will condense water on the outside of a glass), sending the water to a drain and removing water vapor from the cooled space and lowering the relative humidity.
The comfort air conditioner is designed to create a 40% to 60% relative humidity in the occupied space. In food retailing establishments large open chiller cabinets act as highly effective air dehumidifying units.
A specific type of air conditioner that is used only for dehumidifying is called a dehumidifier. A dehumidifier is different from a regular air conditioner in that both the evaporator and condensor coils are placed in the same air path, and the entire unit is placed in the environment that is intended to be conditioned (in this case dehumidified), rather than requiring the condensor coil to be outdoors. Having the condensor coil in the same air path as the evaporator coil produces warm, dehumidified air. The evaporator (cold) coil is placed first in the air path, dehumidifying the air exactly as a regular air conditioner does. The air next passes over the condensor coil re-warming the now dehumidified air. Note that the terms “condensor coil” and “evaporator coil” do not refer to the behavior of water in the air as it passes over each coil; instead they refer to the phases of the refrigeration cycle. Having the condensor coil in the main air path rather than in a separate, outdoor air path (as in a regular air conditioner) results in two consequences—the output air is warm rather than cold, and the unit is able to be placed anywhere in the environment to be conditioned, without a need to have the condensor outdoors.
It should be noted that in a thermodynamically closed system, any energy input into the system that is being maintained at a set temperature (which is a standard mode of operation for modern air conditioners) requires that the energy removal rate from the air conditioner increases. This increase has the effect that for each unit of energy input into the system (say to power a light bulb in the closed system) this requires the air conditioner to remove that energy. In order to do that the air conditioner must increase its consumption by the inverse of its efficiency times the input of energy. As an example, presume that inside the closed system a 100 watt light bulb is activated, and the air conditioner has an efficiency of 200%. The air conditioner’s energy consumption will increase by 50 watts to compensate for this, thus making the 100 W light bulb use a total of 150 W of energy.
It is typical for air conditioners to operate at “efficiencies” of significantly greater than 100%..However it may be noted that the input (electrical) energy is of higher thermodynamic quality than the output which is basically thermal energy (heat dissipated), See Coefficient of performance.
AUTOMOBILE AIR CONDITIONING
Air conditioning systems are designed to allow the driver and or passengers to feel more comfortable during uncomfortably warm humid or hot trips in a vehicle. Cars in hot climates often are fitted with air conditioning. There has been much debate and discussion on what the usage of an air conditioner does to the fuel efficiency of a vehicle. Factors such as wind resistance aerodynamics and engine power and weight have to be factored into finding the true variance between using the air conditioning system and not using it when figuring out difference in actual gas mileage. Other factors on the impact on the engine and an overall engine heat increase can have an impact on the cooling system of the vehicle.
PORTABLE AIR CONDITIONERS
portable air conditioner is one on wheels that can be easily transported inside a home or office. They are currently available with capacities of about 6,000 to 60,000 BTU/h (1,800 to 18,000 watts output) and with and without electric resistance heaters. Portable true air conditioners come in two forms, split and hose. Evaporative coolers, sometimes called conditioners, are also portable.Air-cooled portable air conditioners are compressor-based refrigerant system that use air to exchange heat, in the same way as a car or typical household air conditioner. With this type of system the air is dehumidified as it is cooled
Heat pump is a term for a type of air conditioner in which the refrigeration cycle is able to be reversed, producing heat instead of cold in the indoor environment. They are also commonly referred to, and marketed as, a reverse cycle air conditioner. Using an air conditioner in this way to produce heat is significantly more efficient than electric resistance heating. Some home-owners elect to have a heat pump system installed, which is actually simply a central air conditioner with heat pump functionality. When the heat pump is enabled, the indoor evaporator coil switches roles and becomes the condensor coil, producing heat. The outdoor condensor unit also switches roles to serve as the evaporator, and produces cold air
RELEVANCE OF FUZZY LOGIC IN THE DEVICES USED FOR PHOTOGRAPHY CAMERA
A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura (Latin for “dark chamber”), an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura. Here the concept of brightness can be treated as a linguistic variable .this variable quantity should be adjusted according to our requirement to obtain good quality of image
Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. A majority of cameras have a lens positioned in front of the camera’s opening to gather the incoming light and focus all or part of the image on the recording surface. Most 20th century cameras used photographic film as a recording surface, while modern ones use an electronic camera sensor. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture.
Traditional cameras capture light onto photographic film or photographic plate. Video and digital cameras use an electronic image sensor, usually a charge coupled device (CCD) or a CMOS sensor to capture images which can be transferred or stored in a memory card or other storage inside the camera for later playback or processing.
Cameras that capture many images in sequence are known as movie cameras or as ciné cameras in Europe; those designed for single images are still cameras. However these categories overlap as still cameras are often used to capture moving images in special effects work and many modern cameras can quickly switch between still and motion recording modes. A video camera is a category of movie camera that captures images electronically (either using analogue or digital technology).
The lens of a camera captures the light from the subject and brings it to a focus on the film or detector. The design and manufacture of the lens is critical to the quality of the photograph being taken. The technological revolution in camera design in the 18th century revolutionized optical glass manufacture and lens design with great benefits for modern lens manufacture in a wide range of optical instruments from reading glasses to microscopes. Pioneers included Zeiss and Leitz.
Auto-focus systems can capture a subject a variety of ways; here, the focus is on the person’s image in the mirror.
Due to the optical properties of photographic lenses, only objects within a limited range of distances from the camera will be reproduced clearly. The process of adjusting this range is known as changing the camera’s focus. There are various ways of focusing a camera accurately. The simplest cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens, usually around 3 metres (10 ft) to infinity, is in reasonable focus. Fixed focus cameras are usually inexpensive types, such as single-use cameras. The camera can also have a limited focusing range or scale-focus that is indicated on the camera body. The user will guess or calculate the distance to the subject and adjust the focus accordingly. On some cameras this is indicated by symbols (head-and-shoulders; two people standing upright; one tree; mountains).
The size of the aperture and the brightness of the scene controls the amount of light that enters the camera during a period of time, and the shutter controls the length of time that the light hits the recording surface. Equivalent exposures can be made with a larger aperture and a faster shutter speed or a corresponding smaller aperture and with the shutter speed slowed down.
A wide range of film and plate formats have been used by cameras. In the early history plate sizes were often specific for the make and model of camera although there quickly developed some standardisation for the more popular cameras. The introduction of roll film drove the standardisation process still further so that by the 1950s only a few standard roll films were in use. These included 120 film providing 8, 12 or 16 exposures, 220 film providing 16 or 24 exposures, 127 film providing 8 exposures (principally in Brownie cameras) and 35mm film providing 12, 20 or 36 exposures – or up to 72 exposures in bulk cassettes for the Leica Camera range.For cine cameras, 35mm film was the original film format but 16mm film soon followed produced by cutting 35mm in two. An early amateur format was 9.5mm. Later formats included 8mm film and Super 8.
The earliest cameras produced in significant numbers used sensitised glass plates and are now termed plate cameras. Light entered a lens mounted on a lens board which was separated from the plate by an extendible bellows. Many of these cameras, had controls to raise or lower the lens and to tilt it forwards or backwards to control perspective . Focussing of these plate cameras was by the use of a ground glass screen at the point of focus.
Large format camera
The large format camera is a direct successor of the early plate cameras and remain in use for high quality photography and for technical, architectural and industrial photography. There are three common types, the monorail camera, the field camera and the press camera. All use large format sheets of film, although there are backs for medium format 120-film available for most systems, and have an extensible bellows with the lens and shutter mounted on a lens plate at the front. These cameras have a wide range of movements allowing very close control of focus and perspective.
Medium format camera
The medium-format cameras has a film negative size somewhere in between the large format cameras and the smaller 35mm cameras. Typically these systems use 120- or 220-film. The most common sizes being 6×4.5 cm, 6×6 cm and 6×7 cm. The designs of this kind of camera shows greater variation than their larger brethren. Ranging from monorail systems, via the classic Hasselblad model with separate backs, to smaller rangefinder cameras. There are even compact amateur cameras available in this format.
The introduction of films enabled the existing designs for plate cameras to be made much smaller and for the base-plate to be hinged so that it could be folded up compressing the bellows. These designs were very compact and small models were dubbed Vest pocket cameras.
Box cameras were introduced as a budget level camera and had few if any controls. The original box Brownie models had a small reflex viewfinder mounted on the top of the camera and had no aperture or focusing controls and just a simple shutter.
As camera and lens technology developed and wide aperture lenses became more common range-finder cameras were introduced to make focussing more precise. The range finder had two separated viewfinder windows one of which was linked to the focusing mechanisms and moved right or left as the focussing ring was turned. The two separate images were brought together on a ground glass viewing screen. When vertical lines in the object being photographed met exactly in the combined image, the object was in focus. A normal composition viewfinder was also provided.
In the single-lens reflex camera the photographer sees the scene through the camera lens. This avoids the problem of parallax which occurs when the viewfinder or viewing lens is separated from the taking lens.
Twin-lens reflex cameras used a pair of nearly identical lenses, one to form the image and one as a viewfinder. The lenses were arranged with the viewing lens immediately above the taking lens. The viewing lens projects an image onto a viewing screen which can be seen from above
A ciné camera or movie camera takes a rapid sequence of photographs on strips of film. In contrast to a still camera, which captures a single snapshot at a time, the ciné camera takes a series of images, each called a “frame” through the use of an intermittent mechanism. The frames are later played back in a ciné projector at a specific speed, called the “frame rate” (number of frames per second). While viewing, a person’s eyes and brain merge the separate pictures to create the illusion of motion. The size and complexity of ciné cameras varies greatly depending on the uses required of the camera. Some professional equipment is very large and too heavy to be hand held whilst some amateur cameras were designed to be very small and light for single-handed operation. In the last quarter of the 20th century camcorders supplanted film motion cameras for amateurs. Professional video cameras did the same for professional users around the turn of the century.
The concept of Probability has nothing in common with fuzziness, these are simply different concepts which superficially seem similar because of using the same unit interval of real numbers [0,1].., since theorems such as De Morgan’s have dual applicability and properties of random variables are analogous to properties of binary logic states.
Fuzzy logic corresponds to “degrees of truth”, while probabilistic logic corresponds to “probability, likelihood”; as these differ, fuzzy logic and probabilistic logic yield different models of the same real-world situations.so one can go for a fuzzy logic rather than probabilistic logic to understand the exact change in the variables and to obtain devices with more efficiency