基于DSP的土工三轴仪数据采集系统的研制

【作者】 王彦华；

【导师】 佟宇；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2004， 硕士

【摘要】 三轴仪是为研究土的应力—应变关系而设计开发出的一种基础科学试验仪器。随着土工试验的日益发展，需要处理的数据量越来越大，对实时性和精度的要求越来越高，原有的三轴仪系统已经远远不能满足土工试验的要求。 本文针对以上问题，分析了目前土工试验对三轴仪数据采集系统的技术要求以及数字信号处理器(DSP)在数据采集、信号处理等方面的应用，研制了以数字信号处理器(TMS320LF2407A)为核心的多通道、高精度三轴仪数据采集系统，实现了数据的采集、滤波和处理。以下是研究的主要工作： 硬件设计方面：根据三轴仪系统中数据采集和处理的实际特点以及前期机械部分的研究工作，设计了以TMS320LF2407、AD7660为核心，SPI总线为基础的多通道、高精度数据采集卡，重点叙述了模拟信号处理模块、DSP模块和液晶扩展模块的设计方法和电路设计方面的内容。 软件设计方面： 1．详细介绍了数据采集系统各模块的软件设计，分析了A／D部分的逻辑时序并给出了其程序流程图。 2．深入研究了信号的采集和处理，在信号的的处理过程中应用了过采样、数字滤波等技术，使得系统在同样模数转换器的条件下，从软件上提高了其采样分辨率，同时还降低了硬件设计中对模拟滤波器的要求。 3．研究了快速傅立叶变换(FFT)在定点DSP中的实现和算法，使得采集的压力信号能够在频域中得到更为全面的分析。 通过三轴仪数据采集系统实现了对土样的压力信号采集和处理，从而验证了土的本构关系(即：土的应力、应变、强度和时间这四个变量之间的内在关系)以及土与结构物相互作用的规律，建立了土的强度-变形理论，满足了三轴仪试验的要求更多还原

【Abstract】 Triaxial instrument is one kind of basic science research apparatuses. It aims at studying earth stress-strain analysis. With the development of triaxial instrument experimentation, more and more data is required to be processed, as well as real-time and precision is desired to be enhanced .So initial triaxical instrument can’t meet the demand of soil test.Considering above-mentioned problems, the technique requirements of triaxial instrument in soil test and the applications of DSP in data acquiring and signal processing are analyzed. A muti-channel, high-precise data acquisition system based on DSP techniques has been designed for implementing data acquiring, filtering and processing .The main work of this paper is showed as follows:In the aspect of hardware, According to the actual conditions of data-acquiring and processing in triaxical instruments and previous research on mechanism, a multi-channel, high-precision data acquisition card based on SPI-BUS, TMS320LF2407 and AD7660 is successfully designed .The circuit design and the design method about analog signal processing, DSP and LCD extended module are emphasized.In the aspect of software, main achievements include:First, software design for each module of data acquisition systems and analysis on logic timing of A/D are elaborated and the software program flowcharts are also givenSecond, the acquisition and processes of signal is further studied. Due to application of the oversampling and digital filter techniques during the signal processing, sample resolution is improved from the aspect of software under the same bit of ADC; simultaneously the demand of hardware for analog filter is reduced.Third, the implementation and algorithm of FFT in fixed-point DSP are studied, so that the acquired stress signal can be completely analysed in the frequency domain.By using of the triaxial instrument data acquisition system, the acquisition and processing of soil pressure signal are accomplished. The soil structure relationship that is an internal relation between the soil stress, strain, intensity and time and the interaction rule between soil and structures are validated .The soil theory of intensity -distortion is established. Results show that the designed triaxial instrument data acquisition system can meet the demand of triaxial experimentation.更多还原