Resarch On Servo Control System For Industrial Sewing Machine

With the rapid development of sewing industry, the performance of sewing equipment is demanded higher and higher. Because of the large volume, huge energy consumption, poor performance in adjusting speed and positioning of the traditional industrial sewing machine with clutch motor, it is not suitable for high performance sewing. In most industrial sewing machines with servo controller, the speed and position information of the motor is measured by the photoelectric sensor, with high production and maintenance cost. Due to the lack of energy feedback function, the braking energy from the frequently stopping is comsumed by the brake resistor.This thesis aims at the servo control system for the industrial sewing machine with permanent magnet synchronous motor (PMSM), and the surface mounted PMSM is selected as the actuator motor. A servo control system with rapid speed response, accurate needle positioning, perfect sewing function, speed sensorless control, and function of energy feedback is designed.The main researches and innovations are as follows:(1) In order to improve the static and dynamic performances of the traditional speed control system, a vector control strategy based on kinetic energy storage of the rotor is proposed. Taking account into the rotational inertia and load torque ripple, a load feedforward compensation method is introduced. The results of simulation and experiments show that the proposed control strategy is able to enhance the static and dynamic performances of the control system compared to the traditional vector control strategy with two closed-loops.The strategy can overcome the adverse effects of rotational inertia and load torque fluctuations.(2) For the shortcomings of the mechanical position sensor in the servo control system, an Extended Kalman Filting (EKF) based speed sensorless control scheme is studied. In the EKF algorithm, the ant colony algorithm is introduced to the selection of the covariance matrixes. The simulation and experimental results demonstrate the validity of the sensorless PMSM controller with the EKF method based on ant colony algorithm for tuning the Q and R parameters.(3) For the recycling of the braking energy due to stopping frequently of the industrial sewing machine, a single-phase rectifier based energy feedback system is designed, and the control method of the rectifier is analyzed. A deadbeat control strategy with current correction is proposed, and the energy storaged in capacity is applied as the variable of the outer loop with the feedforward of the motor side power. The experiment results illustrate the effectiveness and feasibility of the proposed control strategy.(4) The dedicated hardware system for the industrial sewing machine is designed according to the specific requirements of sewing operation. The control strategies in this paper are applied to the experimental hardware platform of the servo control system for the industrial sewing machine. The experimental results show that the developed servo control system has accurate needle positioning and rapid response, can meet the need of high-precision complex sewing operations, and is stable and reliable.