The general principle, adjustment method and steps of PID parameter adjustment are briefly described.

I. General rules for parameter adjustment:

According to the control law of each parameter, the ratio P makes the reaction faster, the differential D makes the reaction earlier, and the integral I makes the reaction lag. In a certain range, the greater the values of p and d, the better the adjustment effect. The adjustment principle of each parameter is as follows:

1, when the output does not oscillate, increase the proportional gain p.

2. When the output does not oscillate, reduce the integration time constant ti.

3. When the output does not oscillate, increase the differential time constant Td.

Second, the PID controller parameter setting method:

1, theoretical calculation setting method. It mainly determines the controller parameters through theoretical calculation according to the mathematical model of the system. The calculated data obtained by this method cannot be used directly, and must be adjusted and corrected through engineering practice.

2. The engineering setting method mainly depends on the engineering experience, and is directly carried out in the control system test, which is simple and easy to master and widely used in engineering practice.

The engineering tuning methods of PID controller parameters mainly include critical proportion method, response curve method and attenuation method. The three methods have their own characteristics, and the similarities are all through experiments, and then the parameters of the controller are adjusted according to the engineering experience formula. At present, the critical proportion method is generally used.

The steps of tuning PID controller parameters by this method are as follows:

(1) First, preselect a sampling period short enough for the system to work.

(2) Only add the proportional control link until the step response of the system to the input appears critical oscillation, and write down the proportional magnification and critical oscillation period at this time.

(3) Under a certain degree of control, the parameters of PID controller are calculated by formula. ?

Three. General steps of parameter adjustment:

1, determine the proportional gain.

P When determining the proportional gain p, first remove the integral and differential terms of PID, generally Ti=0, Td=0, and PID is purely proportional adjustment.

The input is set to 60%~70% of the maximum allowed by the system, and the proportional gain p increases gradually from 0 until the system oscillates.

On the contrary, the proportional gain p gradually decreases from this time until the system oscillation disappears, and the proportional gain p at this time is recorded, and the proportional gain p of PID is set to 60%~70% of the current value. The debugging of proportional gain p is completed.

2. Determine the integration time constant ti.

After the proportional gain p is determined, the initial value of the larger integration time constant Ti is set, and then Ti is gradually reduced until the system oscillates, and then Ti is gradually increased until the system oscillation disappears. Record the Ti at this Time, and set the integral time constant ti of PID to 150%~ 180% of the current value. The debugging of integral time constant ti is completed.

3. Determine the differential time constant Td.

Generally, there is no need to set the differential time constant Td, which can be 0. If you want to set it, it is 30% when it does not oscillate, just like the method of determining P and Ti.

4. Debug the system with no-load and load, and then fine-tune the PID parameters until the requirements are met.

Extended data:

Commonly used Pid formula:

Parameter adjustment finds the best order from small to large.

First integrate the proportion, then add the differential.

The curve oscillates frequently, so the proportional reel should be enlarged.

The curve floats around Dawan, and the proportional belt turns to the small plate.

The recovery of curve deviation is slow and the integration time is reduced.

The curve has a long fluctuation period and a longer integration time.

The oscillation frequency of the curve is fast, and the differential is reduced first.

The dynamic difference is large and the fluctuation is slow. The differentiation time should be prolonged.

There are two waves in the ideal curve, which are 4 1 higher before and lower after.

At first glance, the quality of adjustment will not be low.

References:

Baidu encyclopedia-PID control