digitalcontrol

Digital control is a branch of control engineering in which a controller is implemented as software running on a digital processor. The plant is sampled at discrete times, the controller computes a control signal from the measured outputs, and the signal is converted back to the actuator via a digital-to-analog converter. This discrete-time operation distinguishes digital control from continuous-time (analog) control. Digital control relies on discrete models, commonly represented in the z-domain or as difference equations derived from discretization of a continuous model.

Key components include sensors with analog-to-digital converters, actuators with digital-to-analog converters, and a processor such as a microcontroller, DSP, or FPGA. The sampling rate and processing delay influence stability and performance and must be chosen to capture the plant dynamics and meet real-time requirements. Quantization and finite word length introduce errors that must be accounted for in design.

Many digital controllers implement PID control in discrete time, but a broad range of methods is used, including state-space controllers, model predictive control, and robust or adaptive schemes. Design often starts with discretization of a continuous controller (for example via the zero-order hold or bilinear transform) or by direct discrete-time modeling and pole placement.

Applications span manufacturing, robotics, aerospace, automotive control, power electronics, and consumer electronics. Advantages of digital control include flexibility, ease of integration with digital networks, reproducibility, and the ability to implement complex algorithms. Limitations include processing delays, finite precision effects, and sensitivity to sampling rate relative to plant dynamics.