Intelligent positioning system based on sound propagation (question F)--2023 National College Student Electronic Design Competition question

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1. Task

Based on the natural frequency of the object and the sound propagation characteristics in the medium, we apply algorithms such as pattern recognition and machine learning to design and produce an intelligent positioning system to detect and locate knocking sound sources or placed objects in a specific area.
The system includes a horizontally placed square plane plate with a side length of 450mm. The top view and Cartesian coordinate system definition are shown in Figure 1. The specific area M is a square with a side length of 300 mm, and its center is defined as the coordinate origin O. A square of 60 mm × 60 mm at the four corners of the flat panel is defined as area Z. Electroacoustic or acoustic-electric conversion components are installed in area Z to excite or detect the acoustic signals propagating inside the flat panel.

1) Make a homemade signal generator to generate a step sweep signal with a frequency range of 15kHz~20kHz, a step frequency of 1kHz, and a sweep period of 5 seconds. The electroacoustic component converts it into an acoustic signal and injects it into the flat plate. The acoustic signal is received by any acoustic-electric conversion component that is not at the same position. A test port is reserved and the received signal is observed through an oscilloscope.
2) Divide the area M evenly into 6×6 large squares according to the thick red frame line in Figure 2. After starting the system with one click, tap once in the designated square, and the system will complete the detection and positioning within 5 seconds and display the corresponding square number. The display format is that the horizontal axis number is at the front and the vertical axis number is at the back, separated by commas, for example: (EF, 0304), (GH, 1112).

1) Divide the area M evenly into 12×12 small squares according to Figure 2. After placing the magnet disc in a designated square, start the system with one click. It will complete the positioning within 15 seconds and display the number of the square where the disc is located. The display format is that the horizontal axis number is in front and the vertical axis number is in the back. Separate them with commas, for example: (E, 08), (I, 10).
2) After placing the magnet disc at any designated position in the area M, start the system with one click. The positioning will be completed within 20 seconds and its rectangular coordinate value will be displayed. The unit is mm. The horizontal axis coordinate is in the front and the vertical axis coordinate is in the back. , separated by commas, for example: (-50mm, 100mm). The positioning error is no more than 10mm.
3) Others.

1) The square flat plate should be made of acrylic material. The side length is 450mm10mm; the thickness is uniform and 8mm1mm. Use a marker pen to draw grids and marks on the surface, but no other processing is allowed.
2) The electroacoustic/acoustic components and necessary supporting and fixing components must be installed within the flat panel area Z.
(3) The end face of the flat plate that is struck should be small enough so that the striking position can be distinguished.
4) Use NdFeB magnet discs (diameter 12mm, thickness 2mm), stack 5 pieces each on the flat plate and the lower surface, and the two flat plates will attract each other. The center of the magnet disc serves as the reference position for positioning the play part (2).
5) When testing each task, it is required to switch the system to the corresponding working mode first, and then display or output the results after one-click startup. Between the two tests, it is allowed to reset the system.
6) The detection and positioning functions are limited to the use of acoustic signals propagating inside the flat plate material, and other types of sensors are not allowed.

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