Research Of Signal Generating System Of Vibration Actuating Based On Windows Operation System

Many periodic actuating signals based on PC are used in the test of mechanical vibration. The deficiencies of the previous waveform generators based on simple chip microcomputer and DOS are introduced. In order to deal with the problem, the research of signal generating system of vibration actuating based on Windows operation system is done. The main research in this paper is as follows:Firstly, the operating principle and the selection principle of D/A converter are analyzed. The address decoding circuitry of I/O port and the circuit diagram of D/A transfer card are designed.Secondly, the driver of D/A transfer card is developed by the driver development toolkit. Based on the driver, the D/A transfer card can work correctly in Windows. During the development process of driver, dissimilar program code is generated in response to different development environments. Then the card driver is distributed.The third part of the paper is developing control program of D/A transfer card by Visual C++6.0. Then a general waveform generator controlled by computer program is developed on Windows. Two difficult problems met during programming, how to visit port address of computer and how to design high precision time delay subroutine, are resolved. Sine signal is taken as an example to introduce the programming methods and steps.According to the principle of the general waveform generator, distortion error is caused inevitably in synthesizing waveform. Usually, the distortion error of signal waveform is judged by the total harmonic distortion (THD). The influence of periodic sampling point on THD of synthesized signal waveform is analyzed in detail, and the formulas of THD of synthesized waveform are presented. Because the non-harmonic waves, such as square, triangular and saw-tooth waveform, are natural distorted wave, their formulas of THD are discussed and modified to increase calculated precision.Finally, the vibration test of a simple supported beam is taken as an example to introduce the usage mode of the general waveform generator.