The paper studies the reliability (sensor and actuator failures) of the asymptotic disturbance rejection problem for linear time invariant systems using the factorization approach, assuming that not all loops fail simultaneously and that sensor and actuator do not fail simultaneously. The plant is two-output, i.e. two-vector-output, and the disturbance is at the measured output of the plant. Necessary and sufficient conditions are presented for the general problem and a simple solution is given for problems with stable plants.
Disturbance rejection; Actuator failures; Sensor failures; Stability