Techniques are disclosed relating to control of seismic sources such as marine vibrators. According to some embodiments, iterative learning control (ILC) systems may be used to control such seismic sources. According to some embodiments, a control unit provides first input signals to the marine vibrator which include an excitation signal and a high-amplitude, low-frequency signal, the latter is operable to decrease friction effects in the marine vibrator. Furthermore local sensor(s) placed in, on, or near a seismic source and/or remote sensors placed in the far-field region to measure the acoustic output of the marine vibrator. The control unit is further configured to generate initial values for a transfer function of the marine vibrator based on the measured acoustic output.