Digital control is a branch of control theory that uses digital computers to act as a system. Depending on the requirements, a digital control system can take the form of a microcontroller to an ASIC to a standard desktop computer. Since a digital computer is a discrete system the Laplace transform is replaced with the Z-transform. Also since a digital computer has finite precision (See quantization) extra care is needed to ensure the error in coefficients, A/D conversion, D/A conversion, etc. are not producing undesired or unplanned effects. For the application to living systems, see perceptual control theory. ... A digital system is one that uses numbers, especially binary numbers, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (an analog system) or non-numeric symbols such as letters or icons. ... A computer is a machine capable of undergoing complex calculations. ... A microcontroller (MCU) is a computer-on-a-chip used to control electronic devices. ... An ASIC (application-specific integrated circuit) is an integrated circuit (IC) customised for a particular use, rather than intended for general-purpose use. ... The word discrete comes from the Latin word discretus which means separate. ... In mathematics, the Laplace transform is a powerful technique for analyzing linear time-invariant systems such as electrical circuits, harmonic oscillators, optical devices, and mechanical systems, to name just a few. ... In mathematics and signal processing, the Z-transform converts a discrete time domain signal, which is a sequence of real numbers, into a complex frequency domain representation. ... Quantization of x using Q(x) = floor(Lx)/L. In digital signal processing, quantization is the process of approximating a continuous signal by a set of discrete symbols or integer values; that is, converting an analog signal to a digital one via analog-to-digital conversion. ... This article or section should include material from AD converters In electronics, an analog-to-digital converter (abbreviated ADC, A/D, or A to D) is a device that converts continuous signals to discrete digital numbers. ... In electronics, a digital-to-analog converter (DAC or D-to-A) is a device for converting a digital (usually binary) code to an analogue signal (current, voltage or charges). ...

The need/use of digital control can readily be understood in the use of feedback. Since the creation of the first digital computer in the early 1940s the price of digital computers has dropped considerably, which has made them key pieces to control systems for several reasons Feedback is (generally) information about actions. ... The Atanasoff-Berry Computer was an electronic digital computer [1] [2] and was a major step in the history of computing . ... // Events and trends World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrination, and the use of new, extremely devastating weapons such as the atomic bomb. ...

• Cheap: under $5 for many microcontrollers
• Flexibility: easy to configure and reconfigure through software
• Static operation: digital computers are much less prone to environmental conditions than capacitors, inductors, etc.
• Scaling: programs can scale to the limits of the memory or storage space without extra cost
• Adaptive: parameters of the program can change with time (See adaptive control)

A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal but opposite electric charges have been placed. ... An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... When the parameters of a system are slowly time-varying or uncertain, we need a control law that adapts itself under such conditions to give reliable performance. ...

Digital feedback

One usage of a digital control system is as the controller in a feedback system. The rest of the system can either be digital or analog. Some examples of analog systems with a digital feedback controller are:

• Airplanes
• HVAC
• Motors
• PID controllers
• Radar
• Robotics

The typical setup for a digital feedback controller is Fixed-wing aircraft is a term used to refer to what are more commonly known as aeroplanes in Commonwealth English (excluding Canada) or airplanes in North American English. ... HVAC (pronounced either H-V-A-C or, occasionally, H-VAK) is an initialism/acronym that stands for heating, ventilation and air-conditioning. This is sometimes referred to as climate control. ... A motor is a device that converts energy into mechanical power, and is often synonymous with engine. ... A proportional-integral-derivative controller (PID controller) is a common feedback loop component in industrial control applications (see also control theory). ... M*A*S*H , see Corporal Walter (Radar) OReilly. ... For other uses, see Robot (disambiguation). ...

• A/D conversion as inputs
• D/A conversion as outputs
• A program that relates the outputs to the inputs

The programs can take numerous forms and perform many functions This article or section should include material from AD converters In electronics, an analog-to-digital converter (abbreviated ADC, A/D, or A to D) is a device that converts continuous signals to discrete digital numbers. ... In electronics, a digital-to-analog converter (DAC or D-to-A) is a device for converting a digital (usually binary) code to an analogue signal (current, voltage or charges). ...

• A digital filter for low-pass filtering (analog filters are preferred because digital filters introduce delay)
• A state space model of a system to act as a state observer
• A telemetry system

An FIR filter In electronics, a digital filter is any electronic filter that works by performing digital math operations on an intermediate form of a signal. ... A low-pass filter is a filter that passes low frequencies well, but attenuates (or reduces) frequencies higher than the cutoff frequency. ... In control engineering, a state space representation is a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations. ... A state observer is an extension to a state space model that provides feedback to control a system. ... Telemetry is a technology which allows the remote measurement and reporting of information of interest to the system designer or operator. ...

See also

• Adaptive control
• Analog control
• Control theory
• Digital
• Feedback, Negative feedback, Positive feedback
• Laplace transform
• Real-time control
• Z-transform