What causes hunting in a control system?

In the context of control theory, hunting is a self-induced, undesirable oscillation where a system continuously fluctuates above and below a desired equilibrium value.1

This phenomenon is primarily caused by the system overcorrecting itself in response to a transient or a suddenly applied signal. When a control system lacks sufficient stability, it may overshoot the target value in one direction and then compensate by overshooting in the opposite direction, leading to a continuous, repetitive cycle of correction.21

To mitigate hunting, engineers typically introduce damping into the system. Damping functions by slowing the system's response, which prevents excessive overshoots and helps the system settle at the desired value more effectively. Common methods for implementing damping include:2

• Adding electrical resistance in electronic circuits.2
• Applying mechanical brakes.2
• Using fluid-based resistance, such as forcing oil through a small orifice.2