What is pid - solution - Huaqiang Electronic Network

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1.P proportional control, is to let him take 110 steps, he went to a hundred steps (such as 108 steps) or more than 10 steps (such as 112 steps) at a certain pace to stop.
P proportional control is one of the simplest methods of control. The output of its controller is proportional to the input error signal. The system output has a Steady-state error when there is only proportional control.
2. PI integral control, that is, he walked to step 112 at a certain pace and then went back and forth, went to the 108 step position, and then went back to the 110 step position. Shake back and forth a few times at the 110 step position and finally stop at the 110 step position.
In the integral I control, the output of the controller is proportional to the integral of the input error signal. For an automatic control system, if there is a steady state error after entering the steady state, the control system is said to have a steady state error or a system with Steady-state Error. In order to eliminate the steady-state error, an "integral term" must be introduced in the controller. The integral term versus the error is integrated over time, and as time increases, the integral term increases. Thus, even if the error is small, the integral term increases with time, which pushes the controller's output up so that the steady-state error is further reduced until it equals zero. Therefore, the proportional + integral (PI) controller can make the system have no steady-state error after entering the steady state.
3.PD differential control, that is, he walks to a certain step at a certain step, and then slowly moves to the position of 110 steps. If the final position can be accurately stopped at 110 steps, there is no static difference control; If you stop near step 110 (such as 109 or 111), there is static control.
In the differential control D, the output of the controller is proportional to the differentiation of the input error signal (ie, the rate of change of the error).
The automatic control system may experience oscillation or even instability in the process of overcoming the error. The reason is that there is a large inertia component (link) or a delay component, which has the effect of suppressing the error, and the change is always behind. The change in error. The solution is to make the change of the suppression error "advance", that is, when the error is close to zero, the effect of suppressing the error should be zero. That is to say, it is often not enough to introduce only the “proportional P” term in the controller. The proportional term is only the amplitude of the amplification error, and the current need to increase is the “differential term”, which can predict the trend of error variation. . In this way, the controller with proportional + differential can make the control effect of the suppression error equal to zero or even a negative value in advance, thereby avoiding the serious overshoot of the controlled amount. Therefore, for a controlled object with large inertia or hysteresis, the proportional P+ differential D (PD) controller can improve the dynamic characteristics of the system during the adjustment process.