What is the purpose of integral control in a control system?

Integral control serves a critical role in control systems, particularly in eliminating steady-state errors that may persist despite the system being in operation. This process operates by integrating the error over time, meaning it sums up past errors, allowing the controller to compensate for system bias or disturbances that might prevent the output from reaching the desired setpoint.

When an error is detected—defined as the difference between the desired setpoint and the actual process variable—the integral term begins to accumulate this error. By continuously adjusting the output based on the accumulated error, the integral control action helps bring the system output back to the setpoint. This method ensures that any offset in the system, which could cause a constant deviation from the desired value, is corrected over time, effectively driving the steady-state error towards zero.

The other options focus on different aspects of control functionality. Providing an instant response or measuring the current state addresses different control system dynamics and feedback applications, while variable responses based on input changes suggest a focus on proportional or derivative control mechanisms rather than the cumulative adjustment achieved by integral control.