Self-tuning PID of the Solenoid Response Based on Fiber Squeezer

Solenoids, also called electromagnetic actuators driven by nonlinear magnetic forces, are widely used in many applications. Polarization controllers using fiber squeezer are attractive for their low-loss as well as their low-penalty coherent optical fiber trunk system. However, for the polarization controllers using solenoids as actuators, the stability problem due to the saturation of their magnetic circuit must be studied. In fact, in their conventional configuration, the open-loop stability affects performance and limits applications. Moreover, fluctuations on the performance of solenoids are another major problem especially in industrial applications. These fluctuations are essentially owing to changes in the spring constant, the coefficient of friction, the inductance and resistance of the coil. Preventive maintenance by controlling these parameters is necessary to avoid eventual effects of the parameter variations in the responses of these actuators. This paper proposes a new methodology for smart control of the solenoid response by using polarization controllers based on solenoids that are used as mechanical actuators to exert pressure on optical fiber. The pressure induces optical birefringence that modifies polarization of the light. First, the circuit with PID correctors has been suggested to improve stability performance. Then, a simulation is proposed using Matlab-Simulink software to examine the influence of the solenoid parameters on the corrector constants. The results of the simulation show that if the system parameters change the constants Kp, Ki and Kd of the PID corrector must be adjusted to keep an optimized dynamic response.