Research On Acoustic Localization Technologies Of Multi-target Near-field Sources

Near-field sound source localization technique extensively applied in virtual reality,human-computer interaction, smart home, health care as well as many other areas.2-D MUSIC algorithm is a representative algorithm of the near-field sourcelocalization with performances such as high accuracy, high resolution and robustestimation. Compared with the MUSIC algorithm of Direction–of Arrival (DOA)estimation for far-field source localization,2-D MUSIC algorithm can obtain rangeparameters information about the target sources. However, it is difficult to achieve inthe DSP because of the high computational cost with the two-dimensional spectrumpeak searching. It is important and significant to research near-field source locationmethods with well performance and strong anti-interference ability.The work starts with simulation analysis the2-D MUSIC algorithm and solvesthree problems which are covariance matrix calculation, eigenvalue decompositionand spectrum peak searching on2-D MUSIC algorithm achieving in the DSP. Theprinciple verification system of2-D MUSIC algorithm for the near-field sourcelocalization is developed based on TMS320VC5502hardware platform and tests theperformance of source location. The main work is as follows.(1) The C language program of2-D MUSIC algorithm which needs to achievecovariance matrix solver, eigenstructure and spectral search has been completed.Correlation matrix are deduced with the method of matrix transpose andmultiplication operation, then eigenstructure is realized by QR decomposing andHouseholder transform, besides the hierarchical search method was adopted to realizethe two-dimensional spectral searching. At present, C language implementation of the2-D MUSIC algorithm have been debugged, at the same time.(2) A series of data preprocessing including the Hilbert transform, zero crossingdetection and amplitude normalization have been completed. To solve the problemthat near-field source localization algorithm can only deal with complex data, but the actual system only transmits real data, the method of Hilbert transform is utilized toachieve a real-to-complex conversion. The zero crossing detection and amplitudenormalization method is applied to the sample after data preprocessing, to avoid theproblem that signal amplitude do not match the received array in the actual systemand appear unobvious spectrum peak as well as pseudo peak.(3) A dual-target implementation is proposed whose transmitter exploite frequencydivision and the receiver utilized sub-search threshold as well as detection method.(4) Based on the designed overall project of the principle verification system andthe hardware development platform, four modules are designed and realized. Thetransmitter module consists of a signal generator and a power amplifier, which canlaunch any form of acoustic signals generated by matlab. Being composed of a lownoise amplifier circuit and a band-pass filter circuit, the receiver module can realizeacoustic signal amplification and filtering. Data processing module based onTMS320VC5502processor achieves AD sampling and positional parametercalculation. The display module consists of a microcontroller and LCD screen, whichcan display positioning results in real-time.(5) About3000group experimental tests of near-field and far-field source showedthe positioning accuracy of a single targeting system meet the technical requirements,while the dual targeting system positioning accuracy perform slightly worse.The main contribution of this paper is as follows:(1) Complete the C language program of2-D MUSIC algorithm and put forwarddual targeting implementation, which makes the subspace algorithms really used inthe actual system.(2) Put forward a series of data preprocessing including the Hilbert transform, zerocrossing detection and amplitude normalization, which develop the near-field sourcelocalization algorithm in the actual system,(3) Set up a hardware system for the near-field source localization algorithm,whichcan effectively verify the realizability of2-D MUSIC algorithm.The above work provides a new solution for high-precision near-field acousticpositioning system, which enhances the existing acoustic positioning system.