Abstract: A sewing machine control device performs a closed loop control of an induction motor without using an encoder for detecting the motor speed. The control device includes an inverter for driving the induction motor, and controls the inverter output so that the actual speed of the motor is brought into coincidence with a target speed instructed from a speed instruction device. When the control device executes the inverter control, it uses not only the target speed fed from the speed instruction device but also a detection signal generated from a needle position detector that represents the position of a needle bar and the moving speed thereof.

Abstract: A sewing system includes a plurality of sewing machines and a managing apparatus for managing sewing operations of the sewing machines. The managing apparatus determines a type of a work to be sewn by each of the sewing machines and sewing steps for such work, and supplies an identification code thereof to the sewing machines. A controller of the sewing machine reads out sewing data corresponding to the identification code from sewing data storage, and controls the sewing machine in accordance with the sewing data.

Abstract: A sewing machine with a cloth-edge detector has a light source for casting light on a sensing point on a cloth, and a light receiver for generating an intensity signal according to the intensity of the received light. Before sewing, a reference signal is set at an average of two intensity signals that are gauged before and after a cloth edge. The cloth edge can be detected by comparing the intensity signal from the light receiver with the reference signal.

Abstract: The invention relates to a sewing machine provided with a needle reciprocated according to rotations of a main shaft and work feeding devices actuated synchronously with rotations of the main shaft, setting a margin to sew from a trailing edge to a sewing end position. The sewing machine includes devices for computing a terminal stitch length according to a set margin width. Control devices are provided for controlling a sewing to be carried out for coping with that which corresponds to the terminal stitch length computed by the computing device. The sewing machine further comprises computing devices for applying a correction to at least one of a number of stitches and a feed pitch, as occasion demands, where there arises the remainder as the result of an operation of the computing devices, and control devices for controlling the sewing to be carried out according to the computed result.

Abstract: A sewing machine forms a seam in the form of a series of stitches for a length preset by the operator. The length of the seam formed is computed from feed pitches data each generated when one stitch is formed. The operation of the sewing machine is stopped when the computed seam length coincides with the preset seam length.