Fuzzy logic based control strategies for an electromagnetic actuated sewing machine presser foot

Comunicação apresentada na International Conference on Industrial Technology, Hammamet, Tunisia, 8 - 10 Dezembro 2004.Industrial sewing machines have been significantly improved in recent years and especially electronic sewing control is now being introduced. This study concerns the development of a controller for an electromagnetically actuated presser foot. The controller is responsible for controlling the vertical movement of the presser foot. This is an important point since the presser foot tends to bounce at high sewing speeds, resulting in irregular seams. In this study a fuzzy logic controller was used. The reference displacement value is set up by an adaptive method in order to respect changes on the number of plies. The tested fuzzy logic controller allows a better performance of the control especially in relation with different fabrics. During this study another control strategy was considered. This control strategy combines a PI-algorithm with a fuzzy logic controller. Yet, the controller restricts the use of new fabrics, which have not been defined in advance. This aspect will be a major point in the future development in order to recognize the fabrics during sewing and to adapt the controller adequately.(undefined

Adaptive control of an electromagnetically actuated presser-foot for industrial sewing machines

This study describes some possibilities of setting up an adaptive control method for an electromagnetically actuated presser-foot in an industrial high-speed sewing machine. The control of fabrics feeding in sewing machines is difficult not only because of the complexity of relations between the intervening variables (material properties, sewing speed), but also because in many operations a varying number of material plies are crossed. This implies that the reference for the controller has to be adapted dynamically. Several methods, using PID and/or fuzzy logic control, have been tried and are described in this paper. A preliminary sewing test is able to provide data to tune the controller variables. With these adaptation techniques, the machine would be able to automatically adapt its feeding system according to the material being sewn.Fundação para a Ciência e a Tecnologia (FCT

Improving feeding efficiency of a sewing machine by on-line control of the presser foot

This paper presents a contribution towards the development of a new generation of sewing equipment integrating auxiliary add-on kits to improve performance and flexibility in the production of high-quality garments. An overview of all the recent developments concerning the redesign of the first PC-based controller developed for a novel electromagnetically actuated presser foot on an industrial overlock sewing machine will be presented. Other software modules, developed to ease the establishment of control references and the tuning of the controller parameters, as well as a brief discussion and analysis of the obtained results, will also be described in this paper. According to the latest results here reported, the presser foot firmly controls the fabric plies for a wide range of materials and situations

Automatic presser-foot force control for industrial sewing machines

To develop and test control methods for real-time automatic presser-foot force control in industrial sewing machines. In this work, a closed-loop controller that controls presser-foot maximum vertical displacement is presented and compared to existing solutions that adjust force depending on sewing speed. Automatic force control can reduce problems such as stitch irregularity, stitch distortions and material damage, besides making material handling easier. Design/methodology/approach An electromagnetic force actuator was integrated in an industrial lockstitch machine. A computer-based control system was designed implementing either speed-variable force control, closed-loop control, or emulating a traditional constant-force system. Maximum presser-foot displacement values were measured and analysed in relevant sewing situations, and seam quality was assessed. Findings Constant-force control does not allow optimal force setting at all speeds. Speed-variable force control is an improvement, but requires empirical setting of the speed-force relation, not always assuring optimal operation. Closed-loop control adapts force to the requirement of each sewing situation more precisely. Sewing quality is good and material handling is eased. Research limitations/implications The actuator has to be optimised regarding response time and maximum force. Some aspects in the behaviour of the control system and actuator have to be further studied. Practical implications The proposed control system enables the automatic setting and adaptation of force to all sewing situations, making material handling easier at low speeds without compromising feeding performance at high speed. The closed-loop controller may be used as teach-in system for speed-dependent control. Originality/value This is the first prototype of a closed-loop control system for presser-foot force on a lockstitch sewing machine and the first comparative study of control methods for presser-foot force control.Fundação para a Ciência e a Tecnologia (FCT