Compensation (engineering)

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In engineering, compensation is planning for side effects or other unintended issues in a design. The design of an invention can itself also be to compensate for some other existing issue or exception.

One example is in a voltage-controlled crystal oscillator (VCXO), which is normally affected not only by voltage, but to a lesser extent by temperature. A temperature-compensated version (a TCVCXO) is designed so that heat buildup within the enclosure of a transmitter or other such device will not alter the piezoelectric effect, thereby causing frequency drift.

Another example is motion compensation on digital cameras and video cameras, which keep a picture steady and not blurry.

Other examples in electrical engineering include:

A constant voltage device compensates for low or high voltage in an electrical circuit, keeping its output the same within a given range of input.
Error correction compensates for data corruption.
Gray coding compensates for errors on rotary encoders and linear encoders.
Debouncing compensates for jitter in an electrical switch (see Contact Bounce section in Switch article).
A resistor or inductor compensates for negative resistance in gas-discharge lighting.
Frequency compensation is used in feedback control systems to avert oscillations.

There are also examples in civil engineering:

Expansion joints in sidewalks, buildings, and bridges compensate for expansion and contraction.
Various devices between a structure and its Foundation compensate for earthquake movements, either actively or passively.

[edit] Railways

On railways, steep gradients on sharp curves have an equivalent gradient slightly steeper than the stated value. This is because of extra friction of the wheel on the rails, and because wagons stretch out on the chord rather than on the arc, and may thus cause trains to stall. To compensate, the gradient of ruling grades is slightly reduced from say 1 in 50 to 1 in 53.