A voice coil motor ("VCM") control circuit controls operation of a VCM which positions a disk drive head/actuator arm assembly. A data processor is continuously updated with the current position and relative radial velocity of the disk drive head/actuator arm assembly. The data processor provides signals to a digital-to-analog converter ("DAC") of the VCM control circuit representative of the amount of energy necessary to move the head/actuator arm assembly to a parking position from a current position. The DAC generates an analog signal which is applied to a capacitor. When an undervoltage condition occurs, the signal stored in the capacitor is applied to amplifier circuitry to be used as an initial condition reference signal from which signals are generated to park the head/actuator arm assembly in a desired parking position.