| 摘要 |
PURPOSE:To keep a control deviation at a low level, by having the evaluation for the deviation from the target value and varying the reading period of the control degree or the output period of the operation degree based on the result of evaluation. CONSTITUTION:A timer 11 produces the basic period for process of a DDC computer 4 and then produces a millisecond-based processing period to deliver it to a process starting part 10. The part 10 decides the sampling interval and delivers a process command 12 to a fetching part 7, an output part 8 and an algorism 9 respectively. For the sampling period decided by the part 10, a sampling period of 1/2 basic period is secured for each prescribed period. If the square sum of control deviation of the three preceding samplings is within a specified range after having the above-mentioned sampling, the sampling interval is set back to the original sampling period. In such way, the control deviation is detected for a water level L(t). As a result, the water supply quantity Qin(t) is not kept at a specified level but varies in steps. Thus the water level L(t) is kept at a small control deviation. |
