Fully-digital tension control system with PID algorithm for winding ultra-fine enameled wires

An active fully-digital tension control system with PID algorithm is proposed. Only digital signals are involved and processed throughout the closed-loop control system, which employs the micro-controller unit (MCU) dsPIC33EV256GM102 as the main controller with PID algorithm, incremental photoelectric encoder as the angular sensor and AC servo motor as the actuator. A rod-spring mechanism is indispensably constructed to convert the change of tension to the variation of rod's swing angle. Characteristics of the controlled object are tested and analyzed, from results of which the mathematical model is theoretically deduced. The PID coefficient set is determined by Ziegler and Nichols method. Its practicability is initially validated in simulation using SIMULINK/MATLAB. The prototype is also fabricated and experimented on with ultra-fine enameled wires (0.08mm). In order to enhance the practical performance, PID coefficients are further adjusted in experiments. The results show that the proposed system performs well both in transient process and steady stage. Meanwhile, it has good anti-interference capability as well.