A method for real-time three-dimensional (3-D) ultrasound imaging using a mechanically scanned linear phased array is proposed. The high frame rate necessary for real-time volumetric imaging is achieved using a sparse synthetic aperture beamforming technique utilizing only a few transmit pulses for each image. Grating lobes in the two-way radiation pattern are avoided by adjusting the transmit element spacing and the receive aperture functions to account for the missing transmit elements. The signal loss associated with fewer transmit pulses is minimized by increasing the power delivered to each transmit element and by using multiple transmit elements for each transmit pulse. By mechanically rocking the array, in a way similar to what is done with an annular array, a 3-D set of images can be collected in the time normally required for a single image.
An architecture for the development of on-line models to support future uninhabited aerial vehicles is developed. The architecture is based on a new filter called the Unscented Kalman Filter that approximates the state and noise stochastic distributions, rather than the dynamics. A square root version of the Unscented Kalman Filter is shown to have better characteristics for on-line implementation than traditional methods, such as less sensitivity to tuning, initial conditions, and sample frequency. The estirnation methodology is shown to be able to estimate the nonlinear state and model parameters for an aircraft during failure, and to generate aerodynamic models with potential application to on-line control reconfiguration. 0-7803-7298-0102/$17.00 0 2002 AACC
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