Tracking apparatus

A tracking apparatus for tracking position of a material being transported, the apparatus comprising:

• a plurality spaced apart conveyance tables located along a line and including driven parts which convey a conveyed material toward a target position, the conveyed material having a head end;
• a plurality of sensors detecting the head end of the conveyed material, each sensor being located at a respective detection position between a respective pair of the conveyance tables, the sensors detecting actual head end position of the conveyed material as the conveyed material is conveyed by the conveyance tables;
• a tracking generator which calculates a calculated head end tracking position of the head end of the conveyed material using a conveyance speed of a respective conveyance table as a reference speed;
• reference speed setting means which changes the reference speed of the respective conveyance table based on the calculated head end tracking position of the conveyed material;
• a delay timer delaying, by a time delay, generation of detection signals of the sensors apparently detecting the head end of the material conveyed;
• time delay correcting means which corrects the time delay of the detection signals of the sensors which has been inserted by the delay timer;
• slippage detection means detecting slippage of the conveyed material based on detection by a respective sensor of the head end of the conveyed material, as the conveyed material reaches the detection position of the respective sensor, and the calculated head end tracking position, calculated by the tracking generator;
• and
• correcting means which stops calculation of the calculated head end tracking position, upon detection of slippage by the slippage detection means, and resets calculation of the calculated head end tracking position by the tracking generator, based on correction of the time delay by the time delay correcting means, upon detection of the head end of the conveyed material by the respective sensor.