Development Of Portable Roughness Measuring Instrument Based On Piezoelectric Sensor

The surface roughness is the microscopic and undulating extent between the peaksand valleys. It is the main measuring indicator of the workpiece`s surface machiningaccuracy. To any two or more workpieces, it affects their friction, the worn and thesealing degree between the contacting surfaces, even more the fatigue of the workpieces.the portable roughness measuring instrument that I developed in this article is a handleinstrument used to the production site and the moving measuring. It has these followingcharacteristics: wide range of applications, high precision, multi-parameter calculation,simple operation and compliance the requirements for surface roughness measuringinstrument with ISO international standards.The surface roughness developed in this text is a contact instrument. The contact isa piezoelectric sensor. The output of the sensor is electric charge. Because of itstransient and instability,we should change it into a voltage value.The text is focused on the design of the Q-V conversion circuit, to facilitate thesubsequent analog signal processing. In the digital circuits and signal processing section,this text gives important introduction and design about the minimum system of DSPand the related peripheral equipment and giving the corresponding driver programs andprogram flows. Each device functions properly during commissioning.The text is also focused on the Gaussian filter`s design. Gaussian filter min-line isthe extraction method in international and national standards. The text mostlyintroduces the main characteristics of Gaussian filter. The text researchs multilevelButterworth simulation Guassian approach filter. And then design the type ofIIR(infinitely impulse response)digital Guassian approach filter, getting a good resultafter simulating.The experiment shows that the instrument complies the requirements of nationalstandard, and get the predetermined parameters standards. The instrument is portable,by some sample operation to complete every functions with a fast measuring speed anda high and stable accuracy.