Research And Design On The Servo Control System Of The Lock-stitch Sewing Machine

The boom of rag trade intensifies the market demand for automatic production equipments, the lock-stitch sewing machine as a kind of high-speed sewing machine which is applied in large scale industrial production is undoubtedly typical one. And the servo control system as the core of the lock-stitch sewing machine, directly affects the quality of the products and the cost of production. And the most domestic brands of the lock-stitch sewing machine don't have the independent intellectual property rights of the servo control system, so the research and design of this article for the servo control system is of great significance.At first, this paper introduces the structure and principle of the servo control system. Then, on the basis of the detailed presentation in relation to working principle and mathematical model of the brushless dc motor, we researched, improved and designed a new method to stabilize and control velocity. In order to minimize mechanical shocks, a double closed-loop scheme which consists of current loop and speed loop was adopted in the speed controlling method. The speed loop used fuzzy PID control algorithm, the current loop used comparison algorithm on the basis of the current hysteresis control. And this control scheme was simulated based on modeling for brushless dc motor. The design combined traditional methods including dynamic braking, regenerative braking and plug braking, cooperated with the position control algorithm, could effectively solved the big problem regard to precision of needle stop locating when braked fast.In the whole system, the hardware design chosen TI LM3S1439as the control chip, IRAMS06UP60A chip produced by the International Rectifier Company as power drive modules. The hardware design is reasonable, high integrated, of high reliability. The design of the software was compiled by assembly language and C language with modular method, in order to be convenient to transplant and modify.The servo control system was rapid in responding to Variations of speed, it effectively reduced the mechanical shock noise, reduced the mechanical wear. Meanwhile, the system could quickly complete braking, and ensured accuracy of needle stop locating. After a lot of tests and analysis, the results showed that the servo control system design was rational and feasible, and the performance was stable, reliable, met the lock-stitch sewing machine all kinds of need, had a good market prospect.