| 摘要 |
PURPOSE:To minimize a control error due to a steady deviation so as to approximate to the minimum detection level of a controlled variable detector by correcting a target value based on the deviation of a current value from the target one after a control action according to an original target value is terminated and again executing the control action based on the target value after it is corrected. CONSTITUTION:When a release command B is stopped, a returning device 17 stores a position deviation (e) at that time, that is a positioning error e1, and then outputs its storage value M to an adder 18 (a time t2). Thus a corrected target value Y1+e1 obtained by adding the positioning error e1 to the target value Y1 is given to a control part I, which again starts positioning control based on the corrected target value Y1+e1. The positioning control based on the corrected target value Y1+e1 roughly ends, and the absolute value ¦e¦ of the position error (e) continues more than a reference time T to keep at a value smaller than a termination reference E (a time t3). Then a level comparator 15 starts outputting the 2nd end signal A, and a counter 12 receives the signal and switches its count value (n) to '2'.
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