COPRIME FACTORIZATION DESIGN OF A NOVEL MAGLEV PRESSER FOOT CONTROLLER

The problem of adverse presser foot dynamics affecting seam quality is addressed, and a novel control solution is proposed. The dynamics of a controlled sewing system are derived from first principles. The stan dard lockstitch sewing system with a novel maglev control mechanism is expressed both as a fourth order nonlinear state space model and as a Laplace transfer function. Using the linearized model, coprime factor ization is used to find all stabilizing controllers. A controller prod ucing a desired time domain response is then chosen. The resulting sys tem demonstrates that adverse presser foot dynamics can be controlled and a desired sewing force can be maintained at all times during fabri c feeding and stitch formation.