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Anti-rolling Gyro
Ship stabilizing gyroscopes are a technology developed in the 19th century and early 20th century and used to stabilize roll motions in ocean-going ships. It lost favor in this application to hydrodynamic roll stabilizer fins because of reduced cost and weight. However, since the 1990s, there is renewed interest in the device for low-speed roll stabilization of vessels (Tohmei, Seakeeper, Quick MC2, etc.). Unlike traditional fins, the gyroscope does not rely on the forward speed of the ship to generate a roll stabilizing moment and therefore can stabilize motor yachts while at anchor. However, the latest generation of "zero speed" fins stabilizers (CMC, Humphree, etc.) can stabilize yachts while at anchor thanks to their eccentricity with respect of the shaft. The World War I transport , completed in 1917, was the first large ship with gyro stabilizers. It had two 25-ton, diameter flywheels mounted near the center of the ship, spun at 1100 rpm by AC motors. The gyroscopes' ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Motions
Ship motions are the six degrees of freedom that a ship, boat, or other watercraft can experience. Reference axes The '' vertical/Z axis'', or ''yaw axis'', is an imaginary line running vertically through the ship and through its centre of mass. A yaw motion is a side-to side movement of the bow and stern of the ship. The '' transverse/Y axis'', ''lateral axis'', or ''pitch axis'' is an imaginary line running horizontally across the ship and through the centre of mass. A pitch motion is an up-or-down movement of the bow and stern of the ship. The '' longitudinal/X axis'', or ''roll axis'', is an imaginary line running horizontally through the length of the ship, through its centre of mass, and parallel to the ''waterline''. A roll motion is a side-to-side or port-starboard tilting motion of the superstructure around this axis. Rotational There are three special axes in any ship, called longitudinal, transverse and vertical axes. The angular movements around them—a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stabilizer (ship)
Ship stabilizers (or stabilisers) are fins or rotors mounted beneath the waterline and emerging laterally from the hull (watercraft), hull to reduce a ship's ship motions#Rotational motions, roll due to wind or waves. ''Active fins'' are controlled by a gyroscope, gyroscopic control system. When the gyroscope senses the ship roll, it changes the fins' angle of attack so that the forward motion of the ship exerts force to counteract the roll. ''Fixed fins'' and bilge keels do not move; they reduce roll by hydrodynamic drag exerted when the ship rolls. Stabilizers are mostly used on ocean-going ships. Function Fins work by producing lift (force), lift or downforce when the vessel is in motion. The lift produced by the fins should work against the roll moment of the vessel. To accomplish this, two wings, each installed underwater on either side of the ship, are used. Stabilizers can be: *Retractable - All medium and large cruise and ferry ships have the ability to retract the fins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Stabilizing Gyroscopes USS Henderson 1917
A ship is a large vessel that travels the world's oceans and other navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity and purpose. Ships have supported exploration, trade, warfare, migration, colonization, and science. Ship transport is responsible for the largest portion of world commerce. The word ''ship'' has meant, depending on the era and the context, either just a large vessel or specifically a ship-rigged sailing ship with three or more masts, each of which is square-rigged. The earliest historical evidence of boats is found in Egypt during the 4th millennium BCE. In 2024, ships had a global cargo capacity of 2.4 billion tons, with the three largest classes being ships carrying dry bulk (43%), oil tankers (28%) and container ships (14%). Nomenclature Ships are typically larger than boats, but there is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flywheel
A flywheel is a mechanical device that uses the conservation of angular momentum to store rotational energy, a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, assuming the flywheel's moment of inertia is constant (i.e., a flywheel with fixed mass and second moment of area revolving about some fixed axis) then the stored (rotational) energy is directly associated with the square of its rotational speed. Since a flywheel serves to store mechanical energy for later use, it is natural to consider it as a kinetic energy analogue of an electrical Inductor. Once suitably abstracted, this shared principle of energy storage is described in the generalized concept of an accumulator. As with other types of accumulators, a flywheel inherently smooths sufficiently small deviations in the power output of a system, thereby effectively playing the role of a low-pass filter with respect to the mechanical veloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servomotor
A servomotor (or servo motor or simply servo) is a rotary or linear actuator that allows for precise control of angular or linear position, velocity, and acceleration in a mechanical system. It constitutes part of a servomechanism, and consists of a suitable motor coupled to a sensor for position feedback and a controller (often a dedicated module designed specifically for servomotors). Servomotors are not a specific 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 applications such as robotics, CNC machinery, and automated manufacturing. Mechanism A servomotor is a closed-loop servomechanism that uses position feedback (either linear or rotational position) to control its motion and final position. The input to its control is a signal (either analog or digital) representing the desired position of the output shaft. The motor is paired with some type of positio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Moment Gyroscope
A control moment gyroscope (CMG) is an attitude control device generally used in spacecraft attitude control systems. A CMG consists of a spinning rotor and one or more motorized gimbals that tilt the rotor’s angular momentum. As the rotor tilts, the changing angular momentum causes a gyroscopic torque that rotates the spacecraft. Comparison with Reaction Wheels CMGs and reaction wheels are two common types of spacecraft attitude control actuators and serve the same function, though they differ in mechanics and performance characteristics. The latter apply torque simply by changing rotor spin speed, but the former tilt the rotor's spin axis without necessarily changing its spin speed. CMGs are more mechanically complex than reaction wheels and typically more expensive, but are far more power efficient. For a few hundred watts and about 100 kg of mass, large CMGs have produced thousands of newton meters of torque. A reaction wheel of similar capability would require meg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Attitude Control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle attitude requires actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on the current attitude and specification of a desired attitude. Before and during attitude control can be performed, spacecraft attitude determination must be performed, which requires sensors for absolute or relative measurement. The broader integrated field that studies the combination of sensors, actuators and algorithms is called ''guidance, navigation and control'', which also involves non-attitude concepts, such as position determination and navigation. Motivation A spacecraft's attitude must typically be stabilized and controlled for a variety of reasons. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Stability
Ship stability is an area of naval architecture and ship design that deals with how a ship behaves at sea, both in still water and in waves, whether intact or damaged. Stability calculations focus on center of mass#center of gravity, centers of gravity, buoyancy, centers of buoyancy, the metacenters of vessels, and on how these interact. History Ship stability, as it pertains to naval architecture, has been taken into account for hundreds of years. Historically, ship stability calculations relied on rule of thumb calculations, often tied to a specific system of measurement. Some of these very old equations continue to be used in naval architecture books today. However, the advent of calculus-based methods of determining stability, particularly Pierre Bouguer's introduction of the concept of the metacenter in the 1740s ship model basin, allow much more complex analysis. Master shipbuilders of the past used a system of adaptive and variant design. Ships were often copied from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stabilizer (ship)
Ship stabilizers (or stabilisers) are fins or rotors mounted beneath the waterline and emerging laterally from the hull (watercraft), hull to reduce a ship's ship motions#Rotational motions, roll due to wind or waves. ''Active fins'' are controlled by a gyroscope, gyroscopic control system. When the gyroscope senses the ship roll, it changes the fins' angle of attack so that the forward motion of the ship exerts force to counteract the roll. ''Fixed fins'' and bilge keels do not move; they reduce roll by hydrodynamic drag exerted when the ship rolls. Stabilizers are mostly used on ocean-going ships. Function Fins work by producing lift (force), lift or downforce when the vessel is in motion. The lift produced by the fins should work against the roll moment of the vessel. To accomplish this, two wings, each installed underwater on either side of the ship, are used. Stabilizers can be: *Retractable - All medium and large cruise and ferry ships have the ability to retract the fins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyroscopes
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining Orientation (geometry), 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, due to the angular momentum#Conservation of angular momentum, conservation of angular momentum. Gyroscopes based on other operating principles also exist, such as the microchip-packaged Vibrating structure gyroscope#MEMS gyroscopes, MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state ring laser gyroscope, 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 submer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
