CONTROL SYSTEM FOR SEWING MACHINE

摘要

A semiautomatic sewing system (10) comprises a sewing machine (12), a drive unit (42) including a variable speed motor and encoder for counting stitches sewn, material edge sensors (40) mounted in spaced relationship in front of the needle (22) of the sewing machine, and a microprocessor controller (51) coupled to the sewing machine controls. Accurate control of seam lengths and end points is achieved by initiating countdown of a variable preprogrammed number of final stitches responsive to material edges detected by the sensors (40) only when the stitch count falls within a predetermined window of values so that inaccuracies from stitch counting are limited to a small portion of the overall seam length. If the sensors (40) do not detect a material edge within the window of stitch values, the sewing system (10) reverts to pure stitch counting to determine seam length.