Acceleration of the vibration platform. A-C) Magnitude of acceleration in the x, y, and z directions are shown. As designed, virtually all of the vibration occurs in the vertical or z direction with minimal acceleration in the axes parallel to the platform. D-F) Fast Fourier transform of the vibration signal confirms that the frequency content of the vibration is desired frequency of 30 Hz. It also demonstrated that the z-direction contained most of the frequency content.