ANALOG COMPUTER

An analog computer or analogue computer is a sort of computer that uses the continuously variable components of bodily phenomena including electric, mechanical, or hydraulic portions to model the hassle being solved. In contrast, digital computer systems constitute varying portions symbolically and by means of discrete values of both time and amplitude.

Analog computer systems could have a very wide variety of complexity. Slide rules and nomograms are the best, whilst naval gunfire manipulate computers and large hybrid digital/analog computer systems were a few of the most complicated.Systems for manner manipulate and protecting relays used analog computation to carry out control and shielding features.

Analog computers have been extensively utilized in scientific and business programs even after the appearance of virtual computers, because on the time they had been usually much faster, but they started out to turn out to be out of date as early because the Nineteen Fifties and Nineteen Sixties, even though they remained in use in some unique programs, inclusive of plane flight simulators, the flight laptop in plane, and for teaching control systems in universities. More complex programs, consisting of aircraft flight simulators and synthetic-aperture radar, remained the area of analog computing (and hybrid computing) well into the 1980s, seeing that digital computer systems had been insufficient for the challenge.

TIMELINE OF ANALOG COMPUTERS

 Precursors

 This is a listing of examples of early computation gadgets considered precursors of the modern computers. Some of them might also even have been dubbed 'computer systems' with the aid of the click, even though they'll fail to match cutting-edge definitions.
The Antikythera mechanism, courting between one hundred fifty and one hundred BC, turned into an early analog computer.

The Antikythera mechanism changed into an orrery and is considered an early mechanical analog pc, in step with Derek J. De Solla Price. It was designed to calculate astronomical positions. It became located in 1901 within the Antikythera damage off the Greek island of Antikythera, between Kythera and Crete, and has been dated to c. 100 BC at some stage in the Hellenistic duration of Greece. Devices of a level of complexity corresponding to that of the Antikythera mechanism would not reappear till a thousand years later.

Many mechanical aids to calculation and measurement had been built for astronomical and navigation use. The planisphere changed into first described with the aid of Ptolemy in the 2nd century AD. The astrolabe become invented inside the Hellenistic international in both the first or 2d centuries BC and is frequently attributed to Hipparchus. A aggregate of the planisphere and dioptra, the astrolabe became effectively an analog pc capable of operating out numerous exclusive forms of issues in round astronomy. An astrolabe incorporating a mechanical calendar laptop and gear-wheels turned into invented through Abi Bakr of Isfahan, Persia in 1235. Abū Rayhān al-Bīrūnī invented the primary mechanical geared lunisolar calendar astrolabe, an early constant-stressed understanding processing system with a equipment train and tools-wheels, c. AD one thousand. The castle clock, a hydropowered mechanical astronomical clock invented by means of Al-Jazari in 1206, become the first programmable analog laptop.The area, a calculating device used for solving troubles in percentage, trigonometry, multiplication and department, and for numerous capabilities, which include squares and dice roots, became developed in the overdue 16th century and found application in gunnery, surveying and navigation.

The planimeter turned into a guide tool to calculate the area of a closed determine by means of tracing over it with a mechanical linkage.The slide rule became invented around 1620–1630, shortly after the publication of the idea of the logarithm. It is a hand-operated analog laptop for doing multiplication and division. As slide rule improvement improved, delivered scales provided reciprocals, squares and rectangular roots, cubes and cube roots, in addition to transcendental features including logarithms and exponentials, circular and hyperbolic trigonometry and different capabilities. Aviation is one of the few fields wherein slide policies are still in vast use, specifically for solving time–distance troubles in light plane.

Charles Babbage is considered with the aid of some to be "father of the computer". In 1822, Babbage began layout on the first mechanical pc, the Difference Engine, that sooner or later caused more complex digital designs, although all of the important ideas of modern-day computers are to be discovered in Babbage's Analytical Engine.

In 1831–1835, mathematician and engineer Giovanni Plana devised a perpetual-calendar gadget, which, through a device of pulleys and cylinders may want to are expecting the perpetual calendar for every yr from AD zero (that is, 1 BC) to AD 4000, keeping track of jump years and ranging day duration.The tide-predicting system invented by using Sir William Thomson in 1872 turned into of exceptional software to navigation in shallow waters. It used a device of pulleys and wires to robotically calculate predicted tide degrees for a hard and fast length at a specific vicinity.

The differential analyser, a mechanical analog pc designed to solve differential equations through integration, used wheel-and-disc mechanisms to carry out the integration. In 1876 James Thomson had already mentioned the viable creation of such calculators, but he have been stymied with the aid of the confined output torque of the ball-and-disk integrators.[14] In a differential analyzer, the output of 1 integrator drove the enter of the following integrator, or a graphing output. The torque amplifier became the advance that allowed those machines to work. Starting in the Twenties, Vannevar Bush and others evolved mechanical differential analyzers.

Modern Era

The Dumaresq changed into a mechanical calculating tool invented round 1902 by using Lieutenant John Dumaresq of the Royal Navy. It turned into an analog pc that associated crucial variables of the fire manage hassle to the motion of 1's personal ship and that of a target ship. It was regularly used with other devices, along with a Vickers range clock to generate variety and deflection facts so the gun sights of the deliver may be constantly set. A variety of variations of the Dumaresq have been produced of growing complexity as development proceeded.

By 1912 Arthur Pollen had evolved an electrically pushed mechanical analog laptop for fire-manage systems, based totally on the differential analyser. It was used by the Imperial Russian Navy in World War I.[citation needed]

Starting in 1929, AC community analyzers have been constructed to remedy calculation troubles associated with electrical power systems that had been too large to resolve with numerical methods at the time. These have been essentially scale models of the electrical properties of the tremendous gadget. Since network analyzers should take care of troubles too huge for analytic methods or hand computation, they have been also used to clear up issues in nuclear physics and inside the design of systems. More than 50 massive community analyzers had been built by means of the end of the Fifties.

World War II technology gun administrators, gun facts computer systems, and bomb points of interest used mechanical analog computer systems. In 1942 Helmut Hölzer constructed a totally electronic analog laptop at Peenemünde Army Research Center as an embedded control device (blending device) to calculate V-2 rocket trajectories from the accelerations and orientations (measured via gyroscopes) and to stabilize and guide the missile. Mechanical analog computer systems had been very critical in gun fireplace control in World War II, The Korean War and properly past the Vietnam War; they were made in enormous numbers.

In the period 1930–1945 in the Netherlands Johan van Veen developed an analogue laptop to calculate and predict tidal currents whilst the geometry of the channels are changed. Around 1950 this concept was advanced into the Deltar, an analogue computer helping the closure of estuaries within the southwest of the Netherlands (the Delta Works).

The FERMIAC become an analog computer invented by means of physicist Enrico Fermi in 1947 to resource in his studies of neutron transport. Project Cyclone turned into an analog computer developed with the aid of Reeves in 1950 for the evaluation and design of dynamic structures. Project Typhoon changed into an analog pc developed by means of RCA in 1952. It consisted of over 4000 electron tubes and used a hundred dials and 6000 plug-in connectors to application. The MONIAC Computer become a hydraulic version of a countrywide economic system first unveiled in 1949.

Computer Engineering Associates was spun out of Caltech in 1950 to provide business services the usage of the "Direct Analogy Electric Analog Computer" ("the most important and maximum brilliant general-purpose analyzer facility for the solution of discipline troubles") advanced there via Gilbert D. McCann, Charles H. Wilts, and Bart Locanthi.

Educational analog computers illustrated the principles of analog calculation. The Heathkit EC-1, a $199 educational analog computer, became made by means of the Heath Company, US c. 1960. It become programmed using patch cords that linked nine operational amplifiers and different components. General Electric additionally advertised an "academic" analog computer package of a simple design within the early Sixties including a two transistor tone mills and three potentiometers wired such that the frequency of the oscillator changed into nulled while the potentiometer dials were located via hand to fulfill an equation. The relative resistance of the potentiometer became then equivalent to the method of the equation being solved. Multiplication or division can be completed, relying on which dials have been inputs and which become the output. Accuracy and determination became restrained and a easy slide rule became greater correct—however, the unit did demonstrate the basic precept.

Analog computer designs had been posted in electronics magazines. One example is the PE Analogue Computer, published in Practical Electronics inside the September 1978 version. Another greater cutting-edge hybrid computer design become posted in Everyday Practical Electronics in 2002. An instance described within the EPE Hybrid Computer become the flight of a VTOL aircraft just like the Harrier jump jet. The altitude and velocity of the aircraft were calculated via the analog a part of the pc and despatched to a PC through a digital microprocessor and displayed on the PC screen.

In commercial technique manipulate, analog loop controllers have been used to mechanically modify temperature, go with the flow, pressure, or other system conditions. The generation of those controllers ranged from purely mechanical integrators, via vacuum-tube and strong-state devices, to emulation of analog controllers with the aid of microprocessors.

Electronic Analog Computer

The similarity among linear mechanical additives, which include springs and dashpots (viscous-fluid dampers), and electric additives, which include capacitors, inductors, and resistors is placing in phrases of mathematics. They can be modeled the use of equations of the equal shape.

However, the distinction among these structures is what makes analog computing beneficial. Complex systems regularly aren't amenable to pen-and-paper evaluation, and require some shape of testing or simulation. Complex mechanical systems, together with suspensions for racing cars, are expensive to manufacture and difficult to modify. And taking particular mechanical measurements all through excessive-velocity assessments adds further problem.

By evaluation, it's miles very cheaper to construct an electrical equal of a complicated mechanical gadget, to simulate its conduct. Engineers set up some operational amplifiers (op amps) and a few passive linear additives to form a circuit that follows the equal equations because the mechanical machine being simulated. All measurements may be taken at once with an oscilloscope. In the circuit, the (simulated) stiffness of the spring, as an instance, can be modified by adjusting the parameters of an integrator. The electric device is an analogy to the bodily device, as a result the name, but it is plenty much less expensive than a mechanical prototype, lots simpler to modify, and normally more secure.

The electronic circuit can also be made to run quicker or slower than the physical device being simulated. Experienced users of digital analog computer systems said that they supplied a comparatively intimate manipulate and understanding of the problem, relative to digital simulations.

Electronic analog computers are particularly properly-suited to representing conditions defined via differential equations. Historically, they had been often used whilst a device of differential equations proved very difficult to remedy via conventional method. As a easy example, the dynamics of a spring-mass device can be defined by using the equation m y ¨ + d y ˙ + c y = m g displaystyle mddot y+ddot y+cy=mg displaystyle mddot y+ddot y+cy=mg, with y displaystyle y y because the vertical function of a mass m displaystyle m m, d displaystyle d d the damping coefficient, c displaystyle c c the spring steady and g displaystyle g g the gravity of Earth. For analog computing, the equation is programmed as y ¨ = − d m y ˙ − c m y − g displaystyle ddot y=-tfrac dmdot y-tfrac cmy-g displaystyle ddot y=-tfrac dmdot y-tfrac cmy-g. The equal analog circuit includes  integrators for the state variables − y ˙ displaystyle -dot y displaystyle -dot y (speed) and y displaystyle y y (role), one inverter, and 3 potentiometers.

Electronic analog computers have drawbacks: the price of the circuit's deliver voltage limits the variety over which the variables may additionally vary (since the price of a variable is represented by means of a voltage on a specific wire). Therefore, every trouble have to be scaled so its parameters and dimensions can be represented the usage of voltages that the circuit can deliver —e.G., the predicted magnitudes of the speed and the location of a spring pendulum. Improperly scaled variables could have their values "clamped" by way of the boundaries of the deliver voltage. Or if scaled too small, they could suffer from higher noise tiers. Either hassle can reason the circuit to supply an incorrect simulation of the bodily machine. (Modern digital simulations are an awful lot extra robust to widely various values in their variables, but are nevertheless now not entirely immune to those issues: floating-factor digital calculations assist a massive dynamic variety, however can suffer from imprecision if tiny differences of huge values lead to numerical instability.)
Analog circuit for the dynamics of a spring-mass system (with out scaling factors)
Damped motion of a spring-mass device

The precision of the analog computer readout was restricted mainly via the precision of the readout gadget used, commonly 3 or four massive figures. (Modern digital simulations are a good deal higher in this area. Digital arbitrary-precision arithmetic can offer any desired degree of precision.) However, in maximum cases the precision of an analog pc is absolutely sufficient given the uncertainty of the model traits and its technical parameters.

Many small computers dedicated to specific computations are still part of business regulation gadget, however from the Nineteen Fifties to the Nineteen Seventies, general-reason analog computers had been the best structures speedy sufficient for real time simulation of dynamic structures, specifically within the aircraft, army and aerospace field.

In the Sixties, the major manufacturer changed into Electronic Associates of Princeton, New Jersey, with its 231R Analog Computer (vacuum tubes, 20 integrators) and subsequently its EAI 8800 Analog Computer (solid state operational amplifiers, 64 integrators). Its challenger become Applied Dynamics of Ann Arbor, Michigan.

Although the simple era for analog computers is generally operational amplifiers (also called "continuous modern amplifiers" due to the fact they haven't any low frequency problem), within the Sixties an strive became made in the French ANALAC pc to apply an opportunity era: medium frequency service and non dissipative reversible circuits.

In the Nineteen Seventies every big agency and management concerned with issues in dynamics had a massive analog computing middle, as an example:

    In the United States: NASA (Huntsville, Houston), Martin Marietta (Orlando), Lockheed, Westinghouse, Hughes Aircraft
    In Europe: CEA (French Atomic Energy Commission), MATRA, Aérospatiale, BAC (British Aircraft Corporation).

Written By : Adrish Waheed