PID微分项系数为负有什么物理意义

The derivative term slows the rate of change of the controller output and this effect is most noticeable close to the controller setpoint.Hence,derivative control is used to reduce the magnitude of the overshoot produced by the integral component and improve the combined controller-process stability.However,differentiation of a signal amplifies noise and thus this term in the controller is highly sensitive to noise in the error term,and can cause a process to become unstable if the noise and the derivative gain are sufficiently large.