PURPOSE: To enable highly accurate positional detection of a material, by a method wherein the arrival time at a target position is calculated by the ON- OFF timing of a plurality of material detection sensors provided along the direction of moving material while a timer counting is updated at each change in the ON-OFF state of the material detection sensors to recognize the position of material by calculating the time at which the error is at its minimum from the target arrival time.
CONSTITUTION: Materials 4 and 5 are sent from the upstream and then, as the tip of the material reaches the position of a sensor Se 1 to turn the sensor Se 1 ON from OFF, T 1 is determined from the distance P-L 1 to a deceleration start target position P from the position L 1 of the sensor Se 1 and a material conveying speed υ by f(P-L 1 , υ). Then, the T 1 is set for a set value TP 1 of a deceleration start target position timer and a deceleration start target position timer counter TC 1 is cleared to 0 to start the timer. Then, when a sensor S 2 is turned ON from OFF, as done in the preceding stage, T 2 is determined from P-L 2 and υ and the T 2 is set for the TP 1 while the TC 1 is cleared to 0 to restart the timer. Successively, the same processing is repeated up to the final stage.