Design And Realization Of Middle School Physics Experiment System Based On Intelligent Sensing

In the era of rapid progress in computer technology and sensor technology,education has also presented a new style.Driven by digital technology,the core requirements of teaching have also been transformed into the cultivation of scientific thinking,experimental inquiry,physical concepts,and scientific attitudes.Applying digital technology to middle school physics experiments can effectively improve middle school students’ hands-on ability and cooperation ability,make the traditional experimental education develop towards the exploratory experimental education,improve traditional experiments,and realize experiments that are difficult to complete with traditional instruments.Based on computer technology and sensor technology,the paper designs and realizes a digital physical experiment platform that can carry out different kinds of experiments such as sound,light,force,electricity,and magnetism.Then,the algorithm research was carried out on the speech signal and photoplethysmography(PPG)involved in the two exploratory experiments of "exploration and analysis of temperature,thermal radiation and heart rate" and "exploration and analysis of male and female voice signals".Finally,the experimental platform and algorithm are verified by experiments.The specific work is as follows:(1)Based on the embedded chips N76E003AT20 and NUC230LC2 AE,the hardware system of the experimental platform is designed to realize the simultaneous acquisition,conditioning,conversion and transmission of multi-channel signals.The software system uses the SQL SERVER database for data storage,and is designed and developed based on the WINFORM framework and three-tier architecture.It fulfills the needs of students for digital analysis and visual processing of data during the experiment,as well as the needs of teachers for the management of experimental information such as experimental operation steps and precautions,and for reviewing experimental reports.(2)In order to remove baseline drift signals,it is proposed to fuse Empirical Mode Decomposition(EMD)with smoothing priors to remove baseline drift signals in PPG signals,and introduce the Mann-Kendall method in statistics to judge the trend of the mean of absolute value of the autocorrelation function value of the Intrinsic Modal Function(IMF),and adaptively select the IMF to be processed.It solves the problems of repeatedly artificially setting thresholds after EMD and the over-selection and missing-selection problems caused by fixed thresholds.Matlab simulation shows that compared with the classical EMD algorithm,the smooth prior method and Combination algorithm of VMD and EMD,the proposed algorithm has better effect,with higher Signal-to-Noise Ratio and smaller Mean Square Error.(3)An improved spectral subtraction algorithm is used to denoise the speech signal.And it proposed a voice activity detection algorithm based on the fusion of fractal dimension and mean of absolute value of autocorrelation function,and the selection of over-reduction factor is adjusted on the basis of the proposed voice activity detection algorithm.Matlab simulation shows that compared with traditional spectral subtraction,wavelet transform and Wiener filtering,the improved spectral subtraction algorithm can better preserve speech signals,remove environmental noise and suppress "music noise".The improved spectral subtraction performs better than the other three algorithms on Segment Signal-to-Noise Ratio(seg SNR)and Perceptural Evaluation of Speech Quality(PESQ).(4)In order to test and verify the experimental system and the proposed improved algorithm,we used the experimental platform to complete two experiments of "exploration and analysis of temperature,thermal radiation and heart rate" and "exploration and analysis of male and female voice signals".Experiments show that in the stable state of the human body,the heart rate value finally obtained by the algorithm in this paper is more stable than the other three algorithms,and the speech signal obtained by the improved spectral subtraction can better suppress noise.During the experiment,the hardware system works normally without overheating and other phenomena.The software system runs stably,and there are no phenomena such as freezes or flashbacks.