AUTO-TUNING SYSTEM OF PARAMETER OF PID ADJUSTER

摘要

PURPOSE:To calculate the optimum parameter of a PID automatically on the basis of calculated characteristics by supposing that a controlled system is a system consisting of a secondary delay element and finding out the characteristics of the system by an original calculating means. CONSTITUTION:A PID adjuster 1 inputs the measured value PV(t) of a process variable of the controlled system, calculates the PID and applies the result to the controlled system as a manipulated variable MV3 to control the system. At that time, the PID adjuster 1 calculates the PID parameter and supposes that the controlled system is a system consisting of the secondary delay element and a signal generating circuit 8 outputs a step signal to the controlled system by a command from a command circuit 7. Consequently, a measured value PV(t) is obtained. A gain calculating circuit 17 calculates gain K, a multiplier 10 and integration circuits 11, 14 calculate integration values Z1, Z2 on the basis of a weight function from a function generating circuit 9 and a calculating circuit 15 finds out a natural period T and an attenuation factor tau. A PID parameter calculating circuit 16 calculates the optimum value of the PID parameters on the basis of said calculated results and then outputs the optimum value to a PID operation part 5.