| 摘要 |
PURPOSE:To simplify algorithm and to improve control precision by finding parameters of a PI control expression from a gain, time constant, process variables, and overshoot control time of control response as parameters of a first- order lag system. CONSTITUTION:The measured value (u) of an air capacity detector 7 and measured value (x) of a DO detector 6 are inputted to a controlled system identifying part 12. The identifying part 12 calculates the gain K and time constant T of the first-order lag system from the measured values (u) and (x). A PI control constant adjusting part 13 calculates the proportional gain KP and integral time T1 of a PI controller from the gain K and time constant T. The controlled system identifying part 12 performs the arithmetic at every control period. The PI control constant adjusting part 13 performs the arithmetic so that an attenuation constant xsi and overshoot time tP are constant. Even when the characteristics of a controlled system vary, the overshoot time is constant, so quick response is satisfied and gain characteristics to frequency response are desirable all the time. |
