PID control principle and algorithm

Closed-loop control is a control method based on the output feedback of the control object, which is corrected according to the norm or standard when measuring the deviation between the actual and the plan. For example, to control the speed of a motor, it is necessary to have a measuring speed of the sensor, and the results of feedback to the control line. The closed-loop control algorithm, which has to mention PID, is the simplest one in the closed-loop control algorithm. PID is the proportional (proportion) integral, (Integral) differential, (differential coefficient) abbreviation, respectively represents three kinds of control algorithm. The combination of the three algorithms can effectively correct the deviation of the controlled object, so as to achieve a stable state. As shown in the PID process.

where R (t) represents the given input value, C (t) represents the actual output value, E (t) indicates the amount of signal deviation, and U (t) indicates the amount of correction.

1. Proportion (P), Integral (I), differential (D) control algorithms each have a role:

1), proportion, the basic (current) deviation of the reaction system E (t), the coefficient is large, can speed up the adjustment, reduce the error, but the excessive proportion of the system stability decreased, and even caused the system instability;

2), integral, the cumulative deviation of the reaction system, so that the system to eliminate the steady state error, improve the difference, because there is error, the integral adjustment is carried out, until there is no error;

3), differential, reflect the system deviation signal change rate e (t)-e (t-1), with foresight, can foresee the trend of deviation change, produce advanced control effect, before the deviation has not formed, has been eliminated by the differential regulation, so can improve the system's dynamic

State performance. However, the interference of noise is amplified, and the differential is disadvantageous to the system's anti-jamming.

Neither integral nor differential can function independently and must be mated to proportional control.

Resources:

[1]. The most popular explanation of PID control and the tuning method of PID parameters

[2]. PID Control Algorithm

PID control principle and algorithm