A control system comprises an actuator, a control law and a processor. The actuator positions a control surface and the control law controls the actuator. The processor comprises an open loop module, a corrector, a comparator, and an estimator, and generates model output to direct the control law. The open loop module generates the model output as a function of a model state and a model input. The corrector generates a corrector output as a function of the model output. The comparator generates an error by comparing the corrector output to the model input. The estimator generates the model state as a function of the error, such that the error is minimized as a function of single-input, single-output gain matrix.