Dissertation > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > Mechanical quantity measuring instruments > Displacement measuring instrument

Research on the Integrated Grating Subdividing Digital Display Device Based on DSP

Author LiuJiao
Tutor LiuWanYu
School Harbin Institute of Technology
Course Instrument Science and Technology
Keywords optical grating displacement sensor DSP phase-shifting resister chain QEP USB
Type Master's thesis
Year 2008
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Grating sensor is an important device for precision measuring, which is widely applied in the fields of position measuring, numerical control machine, automation control and so on. When the precision of the Grating sensor is certain, the processing-circuit play an important part in the measure system. It decides the precision and reliability of the measurement system to some extend,and is also a cost-effective way. However, as is restricted by the beam path, the scan frequency of the scanning circuit, the maximum available measuring speed has inverse proportion relationship to the measuring pace of a single grating scale. According to the problem that grating scale hardly achieves high resolution and precision when in high speed, this paper presents a new hardware system to design the integrated grating subdividing digital display device.According to properties of subdivision methods and powerful controlling function of TMS320LF2407A, this paper uses the optical grating displacement sensor and DSP to realize digital measurement. After been processed, the signal is divided by phase-shifting resister chain method, then it is direction-discriminated and further divided using internal QEP circuit of TMS320LF2407A. At last, the display circuit and the controlling circuit are finished. The speed and displacement are detected by the QEP and CAP circuit. and it can achieves an high precision for different speeding by setting different intermitted periods.This system is developed based on Microsoft Visual C++6.0, which finishes the speed and displacement data communication with the computer. Precision is calculated through lots of data. The measurement platform is built and the measurement is compared with Double Frequency Laser Interferometer. Experiments are done to verify the measuring theory and methods, and its precision achieve 1μm. Some experience is summed up, which lays a good foundation of the further research and application of this measuring method.The frame is benefit for integration of measurement and controlling, and realizes miniaturization. The measurement method can be more intuitionistic according to the human-machine interface. It can make lots of machines work together through inspecting and controlling them, which realizes centralized controlling.

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