Which controller type integrates the error over time to eliminate steady-state error?

• A. Proportional Controller
• B. Derivative Controller
• C. Integral Controller
• D. On-Off Controller

Answer: (C)

Integrating the error over time means the controller accumulates past errors and uses that accumulated value to adjust the output. When there’s a constant disturbance or a steady offset between the setpoint and the process, the error persists, so the integral term keeps adding correction until the error is driven to zero. That’s how steady-state error is eliminated in many systems. A proportional controller responds to the present error but leaves a residual offset in steady state, a derivative controller reacts to how quickly the error is changing without removing the steady offset, and an on-off controller simply switches output in a binary fashion, which tends to produce oscillations or a nonzero average error rather than zero offset.