| 摘要 |
PURPOSE:To minimize an overshooting to occur at the time of starting a servo system and to shorten a setting time by adding the second digital control device to execute the proportion control to the first digital control device with a digital compensating filter. CONSTITUTION:A comparator 5 compares a position error signal (b) at the time of sampling and an output signal (h) of a time delaying element 3, when the changing quantity of the position error signal (b) is smaller than the quantity determined beforehand, a signal (j) is generated so that an output signal (i) of a digital compensating filter 4 can be outputted to a changing-over switch 6 as an input (u) to a fine feeding circuit 7, and the digital compensating filter 4 is started by a comparator output signal (j). When the changing quantity of the signal (b) is larger, an output signal (c) of a multiplier 2 is inputted to the fine feeding circuit 7. The fine feeding circuit 7 receives an output signal (u) of the changing-over switch 6, impresses electric currents (d) and (d') to a two-phase linear step motor 8, and as the result, a position signal (x) of a magnetic head 9 is shifted in the direction to minimize the position error signal (b) which is the difference in a target track position signal (a). |
