Servo bandwidth is the maximum trackable

sinusoidal A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the '' sine'' trigonometric function, of which it is the graph. It is a type of continuous wave and also a smooth periodic function. It occurs often in ...

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from '' angular frequency''. Frequency is measured in hertz (Hz) which is ...

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of a ...

A, with tracking achieved at or before 10% of A amplitude is reached. The servo

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

indicates the capability of the

servo Servo may refer to: Mechanisms * Servomechanism, or servo, a device used to provide control of a desired operation through the use of feedback ** AI servo, an autofocus mode ** Electrohydraulic servo valve, an electrically operated valve that c ...

to follow rapid changes in the commanded input. It is usually specified as a frequency in

Hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one her ...

or radian/sec.

Explanation

Bandwidth of systems is generally defined to be the frequency at which the system's amplitude is

\tfrac

times the signal amplitude. But if we apply same logic to servo systems it is difficult to analyze and develop a system to a sufficiently accurate specification. This is because of

ambiguity Ambiguity is the type of meaning in which a phrase, statement or resolution is not explicitly defined, making several interpretations plausible. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement w ...

with regard to frequency at which the amplitude should go to

\tfrac

. A simple and sound definition can be sought regarding this. Let us say we want to design a position

servo control Servo control is a method of controlling many types of RC/hobbyist servos by sending the servo a PWM (pulse-width modulation) signal, a series of repeating pulses of variable width where either the width of the pulse (most common modern hobby ser ...

system with following specifications: * Bandwidth: 10 Hz * Allowed amplitude range : ± 50° The above definition is not enough to design a practical control system. The definitions above have inherent problems with regard to what amplitude the

manufacturer Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a ...

should take to design the servo with 10 Hz bandwidth. If the manufacturer takes the amplitude to be ±20° and rise time for this amplitude to be 0.025 sec (10 Hz sinusoid) and some other manufacturer takes amplitude to be ±50°, the acceleration requirements calculated by two will be very different. This leads us to understand that giving servo bandwidth alone with no amplitude specification is almost useless. Also defining the bandwidth as per normal bandwidth definition does not help (ambiguity with regard to frequency at which the amplitude should go to

\tfrac)

References

{{reflist Wave mechanics Control theory

Explanation

See also

References