Research On Key Technologies Of Multi-target3D Ultrasonic Positioning In A Large Scope

Three-dimensional ultrasonic positioning technology is one of the keytechnologies of indoor positioning and Virtual Reality, which is mainly used fortracking target. The technology can be used for shopping navigation, hospital patientmonitoring, the goods warehouse management and so on. However, the existingspatial positioning system always has detects of limited range and limited targets,which restrict its application in the future.Based on the ultrasonic positioning system, this paper studied the3D ultrasonicpositioning system of large range and multi-target. This paper puts forward a methodwith universal significance of large range and multi-target3D positioning system, andhas researched the3D model and algrithm. This paper has also put forward asuppression algorithm of the same frequency interference for acoustic system, whichcan improve the positioning accuracy of ultrasonic location system.Firstly, aiming at the characteristic of large-scale multi-target system, time,frequency and coding multi-objective distinguishing approach is analysed andcompared, the new method combining time and frequency is designed. This newmethod can make up the detects of complicated equipment in coding system, and thedetects of time-division system of the inverse ratio between the target number and thereal-time.Secondly, aiming at the detects of the small rang of the existing ultrasoniclocation system, the large scale has been divided into some smaller subspaces. Eachsubspace is a basic positioning unit. The space switching method is designed, thismethod is realized by comparing the switching threshold of subspace with ultrasonicsignal intensity of target, when the target signal reaches the switching threshold, theswitching begins. The mosaic between different subspaces is realized by using thismethodFor the detect that the time base signal can easily be disturbed, the basicalgorithm of this paper uses the TDOA method as the three-dimensional positioncoordinate extraction, and has solved the three-dimensional coordinates of the target model by using spherical intersection method. Because the error and resolution hasrelationship with the sensor distribution variable length, so the positioning error hasbeen analysed by using the geometrical theory of3D ultrasonic location system basedon the TDOA method, and the quantitative relationship between the error and sensordistribution length has also been deduced.Aiming at the co-channel frequency of acoustic interference which is difficult tobe removed from3D ultrasound positioning system, nearly5000groups of ultrasonicsignal waveform is analyzed, a careful study of the ratio between the peaks along therising edge is studied, and the "subtraction" way to do a waveform transform of thesignal is aggressively used, which weakens the interference effect of ultrasonic risingedge. Steps to achieve suppression algorithm includes waveform transform,breakpoint location search, breakpoint position adjustment and so on. Theexperimental results show that this method can effectively eliminate the co-channelinterference by using DSP.The innovation ideas of this paper are as follow:(1) On the base of the existing ultrasonic location system, a multi-targetdistinguishing method combined with time and frequency distinction and the spaceswitching method is designed.(2) Error and resolution of3D ultrasound system based on the TDOA method isanalyzed. The quantitative relationship between the error and sensor distributionlength has been deduced.(3) By the steps of waveform transform, breakpoint location search breakpointposition adjustment and so on, the same frequency acoustic interference suppressionalgorithm is proposed, which can effectively eliminate the co-channel interference.