Gravitational force type capillary pipe viscosity instrument high precision automatic timing method

Abstract

The invention discloses the high-precious automatic timing method of a gravity capillary viscometer, which takes a photoelectric sensor as a liquid level measurement part, uses an intermittent sampling method and a changing sample ratio processing technology, uses the Lomanrovski guidelines and a curve-fitting method based on the least squares method, determines the start point and the end point of timing separately so as to obtained the times that the liquid flows through the timing starting scale line and the timing ending line of the gravity capillary viscometer. The method includes the following steps: (1) gathering and pretreating the liquid level detection voltage; (2) determining the changing curve equation of the liquid level detection voltage in non-timing scale line area; (3) determining the start point of curve fitting in the timing scale line area; (4) determining the changing curve equation of the liquid level detection voltage in timing scale line area; (5) carrying on the adaptive fuzzy determine of an intermittent time t of the intermittent sampling.

Description

technical field [0001] A high-precision automatic timing method for a gravity capillary viscometer. The present invention relates to an automatic timing method, in particular to a high-precision automatic timing method for a gravity capillary viscosity measuring instrument, which belongs to the field of opto-mechanical detection and signal processing. It can be used for liquid level detection in other fields. technical background [0002] Gravity capillary viscometer is widely used in chemical industry, textile, medicine, national defense and other industries due to its simple principle and high measurement accuracy. To determine the viscosity of Newtonian liquid, therefore, high-precision timing is one of the key technologies to realize the automatic viscosity measurement of gravity capillary viscometer. [0003] Existing gravity-type capillary viscometer timing methods include: (1) the traditional method is to judge the concave liquid surface of the liquid to be measured ...

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Problems solved by technology

[0003] Existing gravity-type capillary viscometer timing methods include: (1) the traditional method is to judge the concave liquid surface of the liquid to be measured by human eyes and flow through the viscometer scale line, and cooperate with the stopwatch to complete. This method has low work efficiency and The measurement error is large; (2) use photoelectric switch or optical fiber sensor as the detection part, according to the output voltage of the detection part when the liquid level changes, use the comparison circuit and the waveform shaping circuit to complete the detection of the timing start scale line and the timing end scale line, This method can realize automatic timing, but it does not consider the difference in detection voltage caused by the change of the liquid level of different measured liquids, nor does it consider the impact of the concave liquid surface generated when the measured liquid drops, so it will inevitably A large detection error is generated; (3) with the photoelectric sensor as the detection component, when the liquid level changes, the output voltage of the detection component will produce a peak value (minimum value) due to the existence of the concave liquid level. Using a microcontroller, adopt The peak detection method automatically completes the detection of the timing start scale line and the timing end scale line. This method takes into account the impact of the concave liquid surface on the detection accuracy, but at the same time it produces a timing error whose maximum error is the sampling interval time. Considering the hardware The limitation of the liquid level information makes the sampling rate of the liquid level information not too high, so this method will also have a large detection error

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