Active vibration control is the active application of force in an equal and opposite fashion to the forces imposed by external vibration. With this application, a precision industrial process can be maintained on a platform essentially vibration-free.

Many precision industrial processes cannot take place if the machinery is being affected by vibration. For example, the production of semiconductor wafers requires that the machines used for the photolithography steps be used in an essentially vibration-free environment or the sub-micrometre features will be blurred. Active Vibration Control is now also commercially available for reducing vibration in helicopters, offering better comfort with less weight than traditional passive technologies. A machine is any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of tasks. ... See Oscillator (disambiguation) for particular types of oscillation and oscillators. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... An etched silicon wafer In microelectronics, a wafer is a thin slice of semiconducting material, such as a silicon crystal, upon which microcircuits are constructed by doping (for example, diffusion or ion implantation), etching, and deposition of various materials. ... Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ... A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ... Blur is the name of a British rock band. ...

In the past, passive techniques were used. These include traditional vibration dampers, shock absorbers, and the like, all of which attempt to use friction to convert vibration into heat. But these are not sufficient for the increasing requirements for a vibration-free environment. Passive has several meanings: In grammar it describes a grammatical voice. ... Damping is any effect, either deliberately engendered or inherent to a system, that tends to reduce the amplitude of oscillations. ... A shock absorber in United States parlance (sometimes damper in British use) is a mechanical device designed to smooth out or damp a sudden shock impulse and dissipate kinetic energy. ... Friction is the force that opposes the relative motion or tendency of such motion of two surfaces in contact. ... A red-hot iron rod cooling after being worked by a blacksmith. ...

The typical system uses several components:

• A massive platform suspended by several active drivers (that may use voice coils, hydraulics, or other techniques)
• Three accelerometers that measure acceleration in the three degrees of freedom
• An electronic amplifier system that amplifies and inverts the signals from the accelerometers. A PID controller can be used to get better performance than a simple inverting amplifier.
• For very large systems, hydraulic components that provide the high drive power required.

If the vibration is periodic, the control system may adapt to the ongoing vibration, thereby providing better cancellation than would have been provided simply by reacting to each new acceleration without referring to past accelerations. Mass is a property of a physical object that quantifies the amount of matter it contains. ... Voice coil originally described the coil of copper wire mounted to the moving cone of a loudspeaker. ... Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ... A depiction of an accelerometer designed at Sandia National Laboratories. ... The phrase degrees of freedom is used in three different branches of science: in physics and physical chemistry, in mechanical and aerospace engineering, and in statistics. ... This is a hub page for electronics. ... An amplifier can be considered to be any device that uses a small amount of energy to control a larger amount, although the term today usually refers to an electronic amplifier. ... Generally, amplification is a basic process sometimes seen in nature, and often used in processes which involve a signal which must be made stronger. ... To invert means: to make something inverted to use an inverter the process of inversion In Freudian psychology, an invert is a homosexual. ... In information theory, a signal is a flow of information. ... Periodicity is the quality of occurring at regular intervals (e. ...

See also

• Magnetorheological fluid
• Active noise control
• Noise-cancelling headphone