Abstract
A new method aimed at non-contact velocity measurement of moving objectsis proposed. In this method, ultrasonic wave is emitted, the echo field reflected by moving objects is detected by receiver array, and recorded for a certain period of time. The velocity vector field is reconstructed numerically from the recorded signal using digital beamforming techniques. Whole distribution of velocity vector components, both the longitudinal and transverse components can be measured simultaneously. The possible applications are non-invasive measurement of blood flow, observation of high temperature gas, or investigation of moving powder, etc.
In this paper, 2-dimensional case is discussed for feasibility study, however, the principle can be extended to 3-dimensional measurement. The measurement system emits monochromatic sinusoidal ultrasonic wave through a single transmitter and it detects the echo by a linear array of receivers.
Two velocity estimating algorithms are proposed. The accuracy of velocity measurement by the each algorithm is evaluated as the square root of the minimum obtainable variance of the estimate. Several fundamental relations for selection of parameters are obtained.
The experimental measuring system is built utilizing ultrasonic wave in air (40kHz). Computer simulation and experimental results prove the feasibility of the method.
