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Proportional Navigation
For example, if the line of sight rotates slowly from north to east, the missile should turn to the right by a certain factor faster than the LOS-rate. This factor is ''N''. Proportional navigation (also known as PN or Pro-Nav) is a guidance law (analogous to proportional control) used in some form or another by most homing air target missiles.Yanushevsky, page 3. It is based on the fact that two vehicles are on a collision course when their direct line-of-sight does not change direction as the range closes. PN dictates that the missile velocity vector should rotate at a rate proportional to the rotation rate of the line of sight (Line-Of-Sight rate or LOS-rate), and in the same direction. : a_n = N\dot \lambda V Where a_n is the acceleration perpendicular to the missile's instantaneous velocity vector, N is the proportionality constant generally having an integer value 3-5 (dimensionless), \dot \lambda is the line of sight rate, and V is the closing velocity. Since the line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AIM-9 Sidewinder
The AIM-9 Sidewinder (where "AIM" stands for "Air Intercept Missile") is a short-range air-to-air missile which entered service with the US Navy in 1956 and subsequently was adopted by the US Air Force in 1964. Since then the Sidewinder has proved to be an enduring international success, and its latest variants remain standard equipment in most Western-aligned air forces. The Soviet K-13 (AA-2 'Atoll'), a reverse-engineered copy of the AIM-9B, was also widely adopted by a number of nations. Low-level development started in the late 1940s, emerging in the early 1950s as a guidance system for the modular Zuni rocket. This modularity allowed for the introduction of newer seekers and rocket motors, including the AIM-9C variant, which used semi-active radar homing and served as the basis of the AGM-122 Sidearm anti-radar missile. Originally a tail-chasing system, early models saw extensive use during the Vietnam War but had a low success rate. This led to all-aspect capabilities i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabolic Mirror
A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a Mirror, reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave travelling along the axis into a spherical wave converging toward the focus. Conversely, a spherical wave generated by a point source placed in the focus (optics), focus is reflected into a plane wave propagating as a collimated beam along the axis. Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). Since the principles of Specular reflection, reflection are reversible, parabolic reflectors can also be used to collimate radiation from an isotropic source into a parallel beam (optics), beam. In optics, parabolic mirrors are used to gather light in reflecting telescop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motion Camouflage
Motion camouflage is camouflage which provides a degree of concealment for a moving object, given that motion makes objects easy to detect however well their coloration matches their background or breaks up their outlines. The principal form of motion camouflage, and the type generally meant by the term, involves an attacker's mimicking the optic flow of the background as seen by its target. This enables the attacker to approach the target while appearing to remain stationary from the target's perspective, unlike in classical pursuit (where the attacker moves straight towards the target at all times, and often appears to the target to move sideways). The attacker chooses its flight path so as to remain on the line between the target and some landmark point. The target therefore does not see the attacker move from the landmark point. The only visible evidence that the attacker is moving is its looming, the change in size as the attacker approaches. Motion is also used in a vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Regulations For Preventing Collisions At Sea
The International Regulations for Preventing Collisions at Sea 1972 (COLREGs) are published by the International Maritime Organization (IMO) and set out, among other things, the "rules of the road" or navigation rules to be followed by ships and other vessels at sea to prevent collisions between two or more vessels.''Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs)'' , from the IMO (The International Maritime Organisation). Retrieved 13 February 2006. COLREGs can also refer to the specific political line that divides inland waterways, which are subject to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Bearing Decreasing Range
Constant bearing, decreasing range (CBDR) is a term in navigation which means that some object, usually another ship viewed from the deck or bridge of one's own ship, is getting closer but maintaining the same absolute bearing. If this continues, the objects will collide. Risk Sailors, especially deck hands and those who stand watch on the bridge, are trained to watch for this situation and make it known when they detect it happening. The reasoning is subtle: non-sailors who are used to driving automobiles normally are able to detect the possible risk of a collision with implicit reference to the background (e.g., the street, the scenery, the landscape, etc.) At sea, when vessels are borne in water, the sea surface removes this vital visual clue. Unaware individuals tend to gauge the risk of two vessels colliding based on which direction each vessel is heading. In other words, a novice will think that two vessels which appear to be heading apart from each other cannot collid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a test charge between the two points. In the International System of Units, the derived unit for voltage is named '' volt''. The voltage between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in generator, inductors, and transformers). On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, and the thermoelectric effect. A voltmeter can be used to measure the voltage between two points in a system. Often a common reference potential such as the ground of the system is used as one of the points. A voltage can represent either a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyroscope
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation (spin axis) is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum. Gyroscopes based on other operating principles also exist, such as the microchip-packaged MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state ring lasers, fibre optic gyroscopes, and the extremely sensitive quantum gyroscope. Applications of gyroscopes include inertial navigation systems, such as in the Hubble Space Telescope, or inside the steel hull of a submerged submarine. Due to their precision, gyroscopes are also used in gyrotheodolites to maintain direction in tunnel mining. Gyroscope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navigation Constant Illustration
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.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator's position compared to known locations or patterns. Navigation, in a broader 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. History In the European medieval period, navigation was considered part of the set of '' seven mechanical arts'', none of which were used for long voyages across open ocean. Polynesian navigation is probably the earliest form of open-ocean navigation; it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proportional Navigation Example
Proportionality, proportion or proportional may refer to: Mathematics * Proportionality (mathematics), the property of two variables being in a multiplicative relation to a constant * Ratio, of one quantity to another, especially of a part compared to a whole ** Fraction (mathematics) * Aspect ratio or proportions * Proportional division, a kind of fair division * Percentage, a number or ratio expressed as a fraction of 100 Science and art * Proportional fonts * Proportionally fair, a scheduling algorithm * Proportional control, a type of linear feedback control system Other uses * Proportionality (law), a legal principle * Proportion (architecture), describes the relationships between elements of a design * Body proportions, in art, the study of relation of human body parts to each other and the whole See also * Proportional representation Proportional representation (PR) refers to a type of electoral system under which subgroups of an electorate are reflected proportiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Velocity
In physics, angular velocity or rotational velocity ( or ), also known as angular frequency vector,(UP1) is a pseudovector representation of how fast the angular position or orientation of an object changes with time (i.e. how quickly an object rotates or revolves relative to a point or axis). The magnitude of the pseudovector represents the ''angular speed'', the rate at which the object rotates or revolves, and its direction is normal to the instantaneous plane of rotation or angular displacement. The orientation of angular velocity is conventionally specified by the right-hand rule.(EM1) There are two types of angular velocity. * Orbital angular velocity refers to how fast a point object revolves about a fixed origin, i.e. the time rate of change of its angular position relative to the origin. * Spin angular velocity refers to how fast a rigid body rotates with respect to its center of rotation and is independent of the choice of origin, in contrast to orbital angular v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line-of-sight (missile)
In missile guidance, line of sight (LOS) is the line directly between the launcher/tacker and the target Target may refer to: Physical items * Shooting target, used in marksmanship training and various shooting sports ** Bullseye (target), the goal one for which one aims in many of these sports ** Aiming point, in field artillery, f ..., which must be in view. If the target is moving the missile is constantly manoeuvred to be on the line of sight as it changes, this results in the missile flying a curved path to the target (see command to line-of-sight). The same path is flown as in pursuit guidance but without the missile having a seeker. No ranger data is used in the control and no prediction of intercept location made. Literature * Tactical and Strategic Missile Guidance, Paul Zarchan, American Institute of Aeronautics and Astronautics Inc. References * Missile operation Missile technology Tracking Targeting (warfare) {{Missile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
