Research And Design Of ECT Data Acquisition System Based On Kalman Algorithm

Electrical capacitance tomography(ECT)is based on medical CT technology and is a kind of process tomography(PT)technology.ECT has a very good prospect because of its low-cost,non-invasive,and non-destructive characteristics.The ECT system is mainly composed of three parts,namely sensor,data acquisition system and image reconstruction system,in which data acquisition is the most critical intermediate link,and the filtering algorithm plays a very important role in the ECT data acquisition system,whether it is good or not directly determines the precision of data acquisition for ECT system.The filtering of ECT data acquisition system is used as the research object.Based on the analysis of the FIR filter of ECT data acquisition system and the kalman filter with higher filtering efficiency,real-time and precision of data acquisition in ECT system are researched.The main researches are as follows:Firstly,the current research status of capacitance tomography and the present situation of ECT data acquisition system are analyzed,and the deficiencies of the system in filtering are pointed out.The parameters of FIR filter depend on requirements and experience;the kalman filter can have a very good effect on the filtering of white Gaussian noise,but in reality,the noises are complex and it is difficult to filter out all the noises.Secondly,based on the analysis of the working principle of ECT data acquisition system,the kalman filtering algorithm is studied emphatically,and the deficiency of the algorithm is analyzed.It is difficult to determine the statistical characteristics of the noises,and they have a direct impact on the performance of the kalman gain,so multi-wavelet transform is introduced.A new algorithm for fusion of kalman filtering and multi-wavelet transform is proposed,and the concrete steps of the fusion are introduced.The algorithm is to carry on the multi-wavelet four or fifth levels decomposition,and soft or hardthreshold processing in turn.According to MATLAB simulation,the results are analyzed.Finally,the hardware implementation of the algorithm is presented.Based on the principle of multiplexing and folded structure,multi-wavelet decomposition and reconstruction are combined to make high pass filtering and low-pass filtering parallel processing to meet the real-time requirements.Simulation results show that the processing speed of the improved filter of data acquisition for ECT is increased,and the data collected is more accurate than the traditional ECT data acquisition system.It provides a new method to realize the filter for ECT data acquisition system.