Method and apparatus for varying the length of stitches sewn by a sewing machine in dependence upon sewing speed

摘要

An adaptive semi-automatic sewing system (10) comprises a sewing machine (12), a drive unit (42) including a variable speed motor and encoder for counting stitches sewn and for sensing the rotation of the motor, at least one material edge sensor (40) mounted ahead 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 number of final stitches responsive to detection of the material edge of the sensors (40). The speed of the sewing machine at the time the material edge is detected is monitored and compared to a reference speed. The number of final stitches is then dynamically adjusted to compensate for the speed variance from the reference speed.