PID Controller

A PID controller computes a correction signal from three pieces of information: how large the current error is, how long that error has persisted, and how quickly it is changing. The proportional term reacts immediately to the present error, the integral term removes long-term bias by accumulating past error, and the derivative term anticipates future behavior by damping rapid changes. Together they form a practical feedback law because they combine fast response, steady-state accuracy, and stability in one control rule.

Use a PID controller when you need a system to track a target value or reject disturbances using feedback, such as in motor speed control, temperature regulation, drone attitude control, or robotic position control. It is especially useful when the plant is too complex for a simple exact model, but you can measure the error over time.

• Forgetting that the integral term depends on accumulated error over time, not just the current error
• Using the raw derivative of noisy measurements without filtering, which can make the control signal unstable
• Choosing gains independently of the physical system, leading to overshoot, slow settling, or oscillation