Solenoid-operated valve control under adverse mechanical conditions such as vibrations or shocks

This paper describes a method for controlling a solenoid-operated valve (SOV) so that it can detect mechanical vibrations or shocks (accelerations, in general). This feature can be an important safety measure since SOVs are often used in complex systems that contain, for example, dc motors. In case of too large perturbations it becomes possible to issue a stop command. No dedicated sensors are used, such as, for example, accelerometers. Only the feedback current is analyzed. The signal conditioning stage consists only of a low-pass filter — no amplification is done, so the hardware cost is minimal or none. The effect of vibrations can be "seen" in the steady-state, when the PWM command is held constant, but the feedback current oscillates or has sharp amplitude variations (very small but detectable).