Patent ID: 9709979
Date: 2017-07-18
CPC Classifications: F02C,G05B,H02P

Claim:
1. A method of monitoring an actuator system comprising a control device, a torque motor having a voltage Umc across terminals of the torque motor and actuating a servo-valve, and an actuator controlled by the servo-valve, the control device being suitable for delivering to the torque motor a control current Icmd as a function of a current setpoint I_c and of a measured current Imes, the monitoring method comprising: comparing, using the control device, the control current Icmd with a predetermined threshold current Iinhib; inhibiting any signaling of a servo-valve failure, only when the control current Icmd is less than or equal to the predetermined threshold current Iinhib; comparing, using the control device, the voltage Umc measured across the terminals of the torque motor with a predetermined threshold voltage Vthresh, only when the control current Icmd is greater than the predetermined threshold current Iinhib; and raising an alarm and indicating a failure of the servo-valve, only when the voltage Umc measured across the terminals of the torque motor is less than or equal to the predetermined threshold voltage Vthresh, wherein the predetermined threshold current is determined using the following formula: with Zmin being a minimum impedance of the torque motor, and dUmc and dIcmd being inaccuracies in the respective measurements of the voltage Umc across the terminals of the torque motor and the current Icmd.