Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four categories, land navigation, marine navigation, aeronautic navigation. It is the term of art used for the specialized knowledge used by navigators to perform navigation tasks, all navigational techniques involve locating the navigators position compared to known locations or patterns. Navigation, in a sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation, for information about different navigation strategies that people use, visit human navigation. In the European medieval period, navigation was considered part of the set of seven mechanical arts, early Pacific Polynesians used the motion of stars, the position of certain wildlife species, or the size of waves to find the path from one island to another.
Maritime navigation using scientific instruments such as the mariners astrolabe first occurred in the Mediterranean during the Middle Ages, the perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery. Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century, the Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean by this route, in 1492 the Spanish monarchs funded Christopher Columbuss expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of America. In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean, some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines.
By then, only two galleons were left from the original seven, the Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from the Philippines, trying to find a path back to the Americas. He arrived in Acapulco on October 8,1565, the term stems from 1530s, from Latin navigationem, from navigatus, pp. of navigare to sail, sail over, go by sea, steer a ship, from navis ship and the root of agere to drive. Roughly, the latitude of a place on Earth is its angular distance north or south of the equator, latitude is usually expressed in degrees ranging from 0° at the Equator to 90° at the North and South poles. The height of Polaris in degrees above the horizon is the latitude of the observer, similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian. Longitude is usually expressed in degrees ranging from 0° at the Greenwich meridian to 180° east and west, for example, has a longitude of about 151° east.
New York City has a longitude of 74° west, for most of history, mariners struggled to determine longitude
A fire-control system is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a weapon system in hitting its target. It performs the task as a human gunner firing a weapon. The best known United States device was the Norden bombsight, simple systems, known as lead computing sights made their appearance inside aircraft late in the war as gyro gunsights. These devices used a gyroscope to measure turn rates, and moved the gunsights aim-point to take this into account, the only manual input to the sight was the target distance, which was typically handled by dialing in the size of the targets wing span at some known range. Small radar units were added in the period to automate even this input. By the start of the Vietnam War, a new computerized bombing predictor, called the Low Altitude Bombing System, the key advantage is that the weapon can be released accurately even when the plane is maneuvering. Most bombsights until this time required that the plane maintain a constant attitude, the LABS system was originally designed to facilitate a tactic called toss bombing, to allow the aircraft to remain out of range of a weapons blast radius.
The principle of calculating the point, was eventually integrated into the fire control computers of bombers and strike aircraft, allowing level, dive. In addition, as the control computer became integrated with ordnance systems. By the start of World War II, aircraft altitude performance had increased so much that anti-aircraft guns had similar predictive problems, the main difference between these systems and the ones on ships was size and speed. The USN Mk 37 system made similar assumptions except that it could predict assuming a constant rate of altitude change. The Kerrison Predictor is an example of a system that was built to solve laying in real time, simply by pointing the director at the target and aiming the gun at a pointer it directed. It was designed to be small and light, in order to allow it to be easily moved along with the guns it served. The radar-based M-9/SCR-584 Anti-Aircraft System was used to air defense artillery since 1943. In combination with the VT proximity fuze, this system accomplished the feat of shooting down V-1 cruise missiles with less than 100 shells per plane.
This system was instrumental in the defense of London and Antwerp against the V-1, although listed in Land based fire control section anti-aircraft fire control systems can be found on naval and aircraft systems. In the United States, Coast Artillery fire control systems began to be developed at the end of the 19th Century, early systems made use of multiple observation or base end stations to find and track targets attacking American harbors. Fire control in the Coast Artillery became more and more sophisticated in terms of correcting firing data for such factors as weather conditions, provisions were made for adjusting firing data for the observed fall of shells
Power windows or electric windows are automobile windows which can be raised and lowered by pressing a button or switch, as opposed to using a hand-turned crank handle. Packard introduced the first power windows in the 1940 Packard 180 series, in 1941, the Ford Motor Company followed with the first power windows on the Lincoln Custom. Cadillac had a straight-electric divider window on their series 75, Power assists originated in the need and desire to move convertible body-style tops up and down by some means other than human effort. The earliest power assists were vacuum-operated and were offered on Chrysler Corporation vehicles, shortly before World War II, General Motors developed a central hydraulic pump for working convertible tops. This system was introduced on 1942 convertibles built by GM, previously, GM had used a vacuum system which did not have the power to handle increasingly larger and complex convertible top mechanisms. These systems were based on major hydraulic advances made in weapons in preparation for World War II.
The Hydro-Electric system was standard on 1947 model year, the seat and window assist system became available on GM closed cars. The full system was only on the high-end GM convertibles made by Oldsmobile, Buick. It was only available as a package, that is, power assisted windows, front seat and this feature can be identified in 1948 and General Motors model numbers with an X at the end, such as the 1951 Cadillac Sixty Special sedan, model 6019X. The electrically operated hydraulic pump system was shared by Hudson and Packard for their 1948 through 1950 models, the drivers door contained four buttons in addition to the remaining individual windows. Ford had a similar system on higher-end convertibles. Mercury and Ford Sportsman convertibles were equipped with windows on four windows from 1946 through 1948 and Mercury. These systems were used by luxury car models until Chrysler introduced the all-electric operation on the 1951 Imperial. The availability of power windows increased with the use of small, General Motors followed with full electric operation in 1954.
This included four-way and six-way seats, which were introduced in 1956, chevrolet introduced the oddity of power front windows in the 1954 model. Ford introduced full four-door power windows in sedans in 1954, the full-sized 1955 Nash Airflyte models featured optional power windows. Electrically-operated vent windows were available as early as 1956 on the Continental Mark II, the 1960s Cadillac Fleetwood came standard with power front and rear vent windows, in addition to standard power side windows, for a total of eight power window controls on the drivers door panel. Modern heavy-duty highway tractors frequently have an option for power window controls and that is, the compressed air system used for air brakes is used for the windows
A constant-speed propeller is a variable-pitch aircraft propeller that automatically changes its blade pitch in order to maintain a chosen rotational speed. The power delivered is proportional to the product of rotational speed and torque. The operation better suits modern engines, particularly supercharged and gas turbine types, an aircraft propeller operates as the source of thrust that moves the plane forward. When an aircraft is stationary with the spinning, air flows past the narrow leading edge of the propeller. This is the most efficient configuration, as the forces on the propeller are the lowest. As the airplane starts moving forward, the airflow begins to push against the front, wider cross section of the propeller and this balances the tradeoff that fixed-pitch propellers must make between high takeoff performance and high cruise performance. A shallower angle of attack requires the least torque, but the highest RPM and this is similar to a car operating in low gear. When the motorist reaches cruising speed, he slow down the engine by shifting into a higher gear.
This is accomplished in an airplane by increasing the angle of attack of the propeller and this means that the propeller moves more air per revolution and allows the engine to spin slower while moving an equivalent volume of air, thus maintaining velocity. The first attempts at constant-speed propellers were called propellers, which were driven by mechanisms that operated on centrifugal force. Their operation is identical to the Watts governor used to limit the speed of steam, eccentric weights were set up near or in the spinner, held in by a spring. When the propeller reached a certain RPM, centrifugal force would cause the weights to swing outwards, when the airplane slowed down, the RPM would decrease enough for the spring to push the weights back in, realigning the propeller to the shallower pitch. In newer models of constant-speed propellers, oil is pumped through the shaft to push on a piston that drives the mechanism to change pitch. The flow of oil and the pitch are controlled by a governor, consisting of a spring, flyweights.
The tension of the spring is set by the propeller control lever. The governor will maintain that RPM setting until an engine overspeed or underspeed condition exists, when an overspeed condition occurs, the propeller begins to rotate faster than the desired RPM setting. This would occur as the plane descends and airspeed increases, the flyweights begin to pull outward due to centrifugal force which further compresses the speeder spring. As that happens, the piston forward, allowing the pilot valve to open
A rotary encoder, called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code. There are two types and incremental. The output of absolute encoders indicates the current position of the shaft, the output of incremental encoders provides information about the motion of the shaft, which is typically further processed elsewhere into information such as speed and position. Conductive, A series of circumferential copper tracks etched onto a PCB is used to encode the information, contact brushes sense the conductive areas. This form of encoder is now rarely seen except as an input in digital multimeters. Optical, This uses a light shining onto a photodiode through slits in a metal or glass disc and this is one of the most common technologies. Optical encoders are very sensitive to dust, on-Axis Magnetic, This technology typically uses a specially magnetized 2 pole neodymium magnet the same size as the motor shaft that typically requires a custom motor shaft be used.
The accuracy is very bad and does not allow many resolution options and this technology does not typically offer UVW or Z pulse outputs. Due to the 2 pole magnet there is lots of jitter on the due to the internal interpolation. Off-Axis Magnetic, This technology typically employs the use of rubber bonded ferrite magnets attached to a metal hub and this offers flexibility in design and low cost for custom applications. Due to the flexibility in many off axis encoder chips they can be programmed to accept any number of pole widths so the chip can be placed in any position required for the application, Magnetic encoders operate in harsh environments where optical encoders would fail to work. An absolute encoder maintains position information when power is removed from the system, the position of the encoder is available immediately on applying power. An incremental encoder accurately records changes in position, but does not power up with a relation between encoder state and physical position.
Devices controlled by incremental encoders may have to go home to a reference point to initialize the position measurement. A multi-turn absolute rotary encoder includes additional code wheels and gears, a high-resolution wheel measures the fractional rotation, and lower-resolution geared code wheels record the number of whole revolutions of the shaft. An absolute encoder has multiple code rings with various binary weightings which provide a data word representing the position of the encoder within one revolution. This type of encoder is often referred to as a parallel absolute encoder, an incremental encoder works differently by providing an A and a B pulse output that provide no usable count information in their own right. Rather, the counting is done in the external electronics, the point where the counting begins depends on the counter in the external electronics and not on the position of the encoder
A servomotor is a rotary actuator or linear actuator that allows for precise control of angular or linear position and acceleration. It consists of a suitable motor coupled to a sensor for position feedback and it requires a relatively sophisticated controller, often a dedicated module designed specifically for use with servomotors. Servomotors are not a class of motor although the term servomotor is often used to refer to a motor suitable for use in a closed-loop control system. Servomotors are used in such as robotics, CNC machinery or automated manufacturing. A servomotor is a servomechanism that uses position feedback to control its motion. The input to its control is a signal representing the position commanded for the output shaft, the motor is paired with some type of encoder to provide position and speed feedback. In the simplest case, only the position is measured, the measured position of the output is compared to the command position, the external input to the controller. As the positions approach, the error signal reduces to zero, the very simplest servomotors use position-only sensing via a potentiometer and bang-bang control of their motor, the motor always rotates at full speed.
This type of servomotor is not widely used in motion control. More sophisticated servomotors use rotary encoders to measure the speed of the output shaft. Both of these enhancements, usually in combination with a PID control algorithm, allow the servomotor to be brought to its commanded position more quickly and more precisely, a servomotor consumes power as it rotates to the commanded position but the servomotor rests. Stepper motors continue to power to lock in and hold the commanded position. Servomotors are generally used as an alternative to the stepper motor. Stepper motors have some inherent ability to position, as they have built-in output steps. Therefore, on first power up, the controller will have to activate the motor and turn it to a known position. This can be observed when switching on a printer, the controller will move the ink jet carrier to the extreme left. A servomotor will immediately turn to whatever angle the controller instructs it to, the encoder and controller of a servomotor are an additional cost, but they optimise the performance of the overall system relative to the capacity of the basic motor.
With larger systems, where a powerful motor represents a proportion of the system cost
Servo (radio control)
Servos are small, mass-produced servomotors or other actuators used for radio control and small-scale robotics. Most servos are rotary actuators although other types are available, linear actuators are sometimes used, although it is more common to use a rotary actuator with a bellcrank and pushrod. Some types, originally used as sail winches for model yachting, a typical servo consists of a small electric motor driving a train of reduction gears. A potentiometer is connected to the output shaft, some simple electronics provide a closed-loop servomechanism. The position of the output, measured by the potentiometer, is compared to the commanded position from the control. Any difference gives rise to a signal in the appropriate direction, which drives the electric motor either forwards or backwards. When the servo reaches this position, the error signal reduces and becomes zero, almost all modern servos are proportional servos, where this commanded position can be anywhere within the range of movement.
Early servos, and a device called an escapement, could only move to a limited number of set positions. Radio control servos are connected through a standard three-wire connection, two wires for a DC power supply and one for control, carrying a PWM signal, each servo has a separate connection and PWM signal from the radio control receiver. This signal is generated by simple electronics, or by microcontrollers such as the Arduino. This, together with their low-cost, has led to their adoption for robotics. RC servos use a three-pin 0.1 spacing jack which mates to standard 0.025 square pins, the most common order is signal, +voltage, ground. The standard voltage is 4.8 V DC, however 6 V and 12 V has seen for a few servos. The control signal is a digital PWM signal with a 50 Hz frame rate, within each 20 ms timeframe, an active-high digital pulse controls the position. The pulse nominally ranges from 1.0 ms to 2.0 ms with 1.5 ms always being center of range, Pulse widths outside this range can be used for overtravel - moving the servo beyond its normal range.
There are two types of PWM. Each PWM defines a value that is used by the servo to determine its expected position, the first type is absolute and defines the value by the width of the active-high time pulse with an arbitrarily long period of low time. The second type is relative and defines the value by the percentage of time the control is active-high versus low-time, the absolute type allows multiple servos to share one communication channel using relatively simple electronics and is the basis of modern RC servos
While working as an instrument maker at the University of Glasgow, Watt became interested in the technology of steam engines. He realised that contemporary engine designs wasted a great deal of energy by repeatedly cooling and reheating the cylinder, Watt introduced a design enhancement, the separate condenser, which avoided this waste of energy and radically improved the power and cost-effectiveness of steam engines. Eventually he adapted his engine to produce rotary motion, greatly broadening its use beyond pumping water, Watt attempted to commercialise his invention, but experienced great financial difficulties until he entered a partnership with Matthew Boulton in 1775. The new firm of Boulton and Watt was eventually highly successful, in his retirement, Watt continued to develop new inventions though none was as significant as his steam engine work. He developed the concept of horsepower, and the SI unit of power, James Watt was born on 19 January 1736 in Greenock, Renfrewshire, a seaport on the Firth of Clyde.
His father was a shipwright, ship owner and contractor, and served as the towns chief baillie, while his mother, Agnes Muirhead, both were Presbyterians and strong Covenanters. Watts grandfather, Thomas Watt, was a teacher and baillie to the Baron of Cartsburn. Despite being raised by parents, he on became a deist. Watt did not attend regularly, initially he was mostly schooled at home by his mother but he attended Greenock Grammar School. He exhibited great manual dexterity, engineering skills and an aptitude for mathematics, while Latin, when he was eighteen, his mother died and his fathers health began to fail. Watt travelled to London to study instrument-making for a year, returned to Scotland and he made and repaired brass reflecting quadrants, parallel rulers, parts for telescopes, and barometers, among other things. Because he had not served at least seven years as an apprentice, Watt was saved from this impasse by the arrival from Jamaica of astronomical instruments bequeathed by Alexander Macfarlane to the University of Glasgow, instruments that required expert attention.
Watt restored them to working order and was remunerated and these instruments were eventually installed in the Macfarlane Observatory. Subsequently three professors offered him the opportunity to set up a workshop within the university. It was initiated in 1757 and two of the professors, the physicist and chemist Joseph Black as well as the famed Adam Smith, at first he worked on maintaining and repairing scientific instruments used in the university, helping with demonstrations, and expanding the production of quadrants. In 1759 he formed a partnership with John Craig, an architect and businessman, to manufacture and sell a line of products including musical instruments and this partnership lasted for the next six years, and employed up to sixteen workers. One employee, Alex Gardner, eventually took over the business, in 1764, Watt married his cousin Margaret Miller, with whom he had five children, two of whom lived to adulthood, James Jr. and Margaret. His wife died in childbirth in 1772, in 1777 he was married again, to Ann MacGregor, daughter of a Glasgow dye-maker, with whom he had two children, who became a geologist and mineralogist, and Janet
A potentiometer, informally a pot, is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a resistor or rheostat. The measuring instrument called a potentiometer is essentially a voltage divider used for measuring electric potential, potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as transducers, for example. Potentiometers are rarely used to control significant power, since the power dissipated in the potentiometer would be comparable to the power in the controlled load. The resistive element can be flat or angled, each end of the resistive element is connected to a terminal on the case. The wiper is connected to a terminal, usually between the other two. On panel potentiometers, the wiper is usually the terminal of three. For single-turn potentiometers, this wiper typically travels just under one revolution around the contact, the only point of ingress for contamination is the narrow space between the shaft and the housing it rotates in.
Another type is the slider potentiometer, which has a wiper which slides along a linear element instead of rotating. Contamination can potentially enter anywhere along the slot the slider moves in, making effective sealing more difficult, an advantage of the slider potentiometer is that the slider position gives a visual indication of its setting. The resistive element of inexpensive potentiometers is often made of graphite, other materials used include resistance wire, carbon particles in plastic, and a ceramic/metal mixture called cermet. Others are enclosed within the equipment and are intended to be adjusted to calibrate equipment during manufacture or repair and they are usually physically much smaller than user-accessible potentiometers, and may need to be operated by a screwdriver rather than having a knob. They are usually called preset potentiometers or trim pots, some presets are accessible by a small screwdriver poked through a hole in the case to allow servicing without dismantling.
Multiturn potentiometers are operated by rotating a shaft, but by several turns rather than less than a full turn, a string potentiometer is a multi-turn potentiometer operated by an attached reel of wire turning against a spring, enabling it to convert linear position to a variable resistance. User-accessible rotary potentiometers can be fitted with a switch which operates usually at the extreme of rotation. Multiple resistance elements can be ganged together with their contacts on the same shaft, for example. The relationship between position and resistance, known as the taper or law, is controlled by the manufacturer
A reduction drive is a mechanical device to shift rotational speed. A planetary reduction drive is a scale version using ball bearings in an epicyclic arrangement instead of toothed gears. Reduction drives are used in engines of all kinds to increase the amount of torque per revolution of a shaft, common household uses are washing machines, food blenders and window-winders. Planetary drives are used in this situation to avoid backlash, which makes tuning easier, if the capacitor drive has backlash, when one attempts to tune in a station, the tuning knob will feel sloppy and it will be hard to perform small adjustments. Gear-drives can be made to have no backlash by using split gears and spring tension, piston-engined light aircraft may have direct-drive to the propeller or may use a reduction drive. The advantages of direct-drive are simplicity and reliability, but an engine may never achieve full output. For instance, an aero engine has a nominal maximum output of 64 kW at 3,300 RPM, but if the propeller cannot exceed 2,600 rpm.
By contrast, a Rotax 912 has a capacity of only 56% of the Jabiru 2200. The Midwest twin-rotor wankel engine has a shaft that spins up to 7,800 rpm
It was the first such device to transmit drawings to a stationary sheet of paper, previous inventions in Europe had used rotating drums to make such transmissions. The telautographs invention is attributed to Elisha Gray, who patented it on July 31,1888, grays patent stated that the telautograph would allow one to transmit his own handwriting to a distant point over a two-wire circuit. It was the first facsimile machine in which the stylus was controlled by horizontal and vertical bars, the telautograph was first publicly exhibited at the 1893 Worlds Columbian Exposition held in Chicago. What you write in Chicago is instantly reproduced here in fac-simile and you may write in any language, use a code or cipher, no matter, a fac-simile is produced here. If you want to draw a picture it is the same, the artist of your newspaper can, by this device, telegraph his pictures of a railway wreck or other occurrences just as a reporter telegraphs his description in words. By the end of the 19th century, the telautograph was modified by Foster Ritchie, calling it the telewriter, Ritchies version of the telautograph could be operated using a telephone line for simultaneous copying and speaking.
Teleautograph systems were installed in a number of railroad stations to relay hand-written reports of train movements from the interlocking tower to various parts of the station. The teleautograph network in Grand Central Terminal included a display in the main concourse into the 1960s. A Telautograph was used in 1911 to warn workers on the 10th floor about the Triangle Shirtwaist Factory fire that had broken out two floors below. An example of a Telautograph machine writing script can be seen in the 1956 movie Earth vs the Flying Saucers as the device for the mechanical translator. Telautograph Corporation changed its name several times, in 1971, it was acquired by Arden/Mayfair. In 1993, Danka Industries purchased the company and renamed it Danka/Omnifax, in 1999, Xerox corporation purchased the company and called it the Omnifax division, which has since been absorbed by the corporation. Archive of Xerox Omnifax Division website, the successor to Telautograph Corporation, Telautograph historical description Patent images in TIFF format U. S.
Patent 0,386,814 Art of Telegraphy, issued July 1888 U. S, Patent 0,386,815 Telautograph, issued July 1888 U. S. Patent 0,461, 470Telautograph, issued October 1891 U. S, Patent 0,461,472 Art of and Apparatus for Telautographic Communication, issued October 1891 U. S. Patent 0,491,347 Telautograph, issued February 1893 U. S, Patent 0,494,562 Telautograph, issued April 1893
Hydraulics is a technology and applied science using engineering and other sciences involving the mechanical properties and use of liquids or fluids. At a very basic level, hydraulics is the version of pneumatics. Fluid mechanics provides the foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In fluid power, hydraulics are used for the generation, hydraulic topics range through some parts of science and most of engineering modules, and cover concepts such as pipe flow, dam design and fluid control circuitry, pumps. The principles of hydraulics are in use naturally in the body within the heart. Free surface hydraulics is the branch of hydraulics dealing with surface flow, such as occurring in rivers, lakes, estuaries. Its sub-field open channel flow studies the flow in open channels, the word hydraulics originates from the Greek word ὑδραυλικός which in turn originates from ὕδωρ and αὐλός. Early uses of water power date back to Mesopotamia and ancient Egypt, other early examples of water power include the Qanat system in ancient Persia and the Turpan water system in ancient Central Asia.
The Greeks constructed sophisticated water and hydraulic power systems, an example is the construction by Eupalinos, under a public contract, of a watering channel for Samos, the Tunnel of Eupalinos. An early example of the usage of hydraulic wheel, probably the earliest in Europe, is the Perachora wheel, notable is the construction of the first hydraulic automata by Ctesibius and Hero of Alexandria. Hero describes a number of working machines using hydraulic power, such as the force pump, in ancient China there was Sunshu Ao, Ximen Bao, Du Shi, Zhang Heng, and Ma Jun, while medieval China had Su Song and Shen Kuo. Du Shi employed a waterwheel to power the bellows of a blast furnace producing cast iron, Zhang Heng was the first to employ hydraulics to provide motive power in rotating an armillary sphere for astronomical observation. In ancient Sri Lanka, hydraulics were used in the ancient kingdoms of Anuradhapura. The discovery of the principle of the tower, or valve pit. By the first century AD, several irrigation works had been completed.
The coral on the rock at the site includes cisterns for collecting water. They were among the first to use of the siphon to carry water across valleys. They used lead widely in plumbing systems for domestic and public supply, hydraulic mining was used in the gold-fields of northern Spain, which was conquered by Augustus in 25 BC