A fatigue test apparatus includes a control system configured to receive, during a first iteration of a fatigue test of an article under test, a command signal corresponding to a particular test step of the fatigue test. The control system is configured to generate, based on the command signal and during the first iteration, a test output signal to cause a force to be applied to the article under test. The control system is configured to generate an error signal associated with the particular test step during the first iteration. A gain calculation device is configured to generate, based on the error signal, a gain adjustment value associated with the particular test step. A variable gain feedforward device is configured to provide, during a second iteration of the fatigue test and based on the gain adjustment value, a stabilization gain to the control system.