CN110412080B - Temperature, salinity and depth sensor and control method for inhibiting thermal hysteresis effect - Google Patents
Temperature, salinity and depth sensor and control method for inhibiting thermal hysteresis effect Download PDFInfo
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- CN110412080B CN110412080B CN201910594063.7A CN201910594063A CN110412080B CN 110412080 B CN110412080 B CN 110412080B CN 201910594063 A CN201910594063 A CN 201910594063A CN 110412080 B CN110412080 B CN 110412080B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
- G01K7/21—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit for modifying the output characteristic, e.g. linearising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/045—Circuits
- G01N27/046—Circuits provided with temperature compensation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
- G01N27/08—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid which is flowing continuously
Abstract
The invention belongs to the technical field of thermohaline depth sensors, and particularly relates to a thermohaline depth sensor and a control method for inhibiting a thermal hysteresis effect. The method comprises the steps of comparing data (platinum resistance) with a reference temperature sensor (a thermistor in a conductivity sensor probe) integrated with a conductivity sensor and a measurement temperature sensor integrated with a temperature-salt-depth sensor end cover, and selecting a method for inhibiting a thermal hysteresis effect formula according to a difference range to obtain the actual conductivity near the reference temperature sensor so as to correct the error amplitude caused by the thermal hysteresis effect. The method can obviously improve the precision of the measured data when the underwater autonomous mobile observation platform carries the thermohaline depth sensor to pass through the thermocline, thereby making up the defects of the prior related thermohaline depth profile measuring technology.
Description
Technical Field
The invention belongs to the technical field of a thermohaline depth sensor, and particularly relates to a thermohaline depth sensor and a control method for inhibiting a thermal hysteresis effect, which is a deep sea thermohaline depth sensor control method suitable for an underwater autonomous navigation platform.
Background
The technology for measuring the conductivity, temperature and depth of seawater is one of the key technologies for researching and utilizing the rapid change of the ocean and global climate. Since the early 70 s of the 20 th century, a temperature, salinity and depth (CTD) sensor is used as an important hydrological investigation tool, can acquire environmental parameters of marine physics, and provides important basic data of temperature, salinity and depth for the research of the marine physics in the aspects of environment, flow field, hydrodynamic force and the like.
The underwater autonomous mobile observation platform comprises various system devices such as an underwater robot, an underwater glider, a manned deep submersible operation device and the like, can move flexibly and has the deep sea hydrodynamics multi-parameter observation and operation sampling capacity, and high-quality temperature and salt depth data is required for the layered sampling of seawater samples and the precise control of the sampling of seabed sediments. CTD sensors have a thermal hysteresis effect, which is caused by the heat stored in the conductivity cell. The thermal hysteresis effect is the temperature abnormity of the cylinder and the rectangular cylinder caused by the heat stored by the fluid passing through the wall surface of the cylinder of the conductivity cell under the assumption of quasi-steady-state heat transfer, has influence on the calculation of salinity, and can derive a numerical model of the effect.
When the underwater autonomous mobile observation platform passes through the thermocline, the heat stored in the conductivity cell can be diffused to the surroundings to obviously influence the measurement accuracy of the conductivity sensor and the temperature sensor. When the underwater autonomous mobile observation platform enters cold water from warm water, usually in a submerged state, the measured value is larger than the true value, resulting in obtaining a larger salinity. When the underwater autonomous mobile observation platform enters warm water from cold water, which is usually in a floating state, the measured value is smaller than the true value, resulting in obtaining less salinity.
Most of the existing commercial thermohaline depth measuring instruments for section measurement do not have the function of inhibiting the thermal hysteresis effect and corresponding control methods, and cannot be well suitable for the application requirements of the thermohaline depth field measurement of the deep sea underwater autonomous mobile observation platform.
Disclosure of Invention
Aiming at the technical problems, the invention provides a temperature and salt depth sensor control method which is suitable for an underwater autonomous mobile observation platform and has the function of inhibiting the thermal hysteresis effect. According to the method, a high-precision and quick-response temperature sensor is respectively integrated on a conductivity sensor and an end cover of a temperature and salt depth sensor; the temperatures measured by the two temperature sensors are compared, and whether an algorithm for inhibiting the thermal hysteresis effect is carried out or not is judged according to the magnitude and the range of the absolute value of the temperature difference, and a thermal hysteresis effect correction formula and a mathematical model are selected.
The invention is realized by the following technical scheme:
a warm salt depth sensor, comprising: the pressure-resistant cabin comprises a pressure-resistant cabin body, an end cover arranged on the pressure-resistant cabin body, a platinum resistor, a pressure sensor and a conductivity sensor;
the conductivity sensor comprises a conductivity probe and a thermistor, the conductivity probe comprises a through hole-shaped conductivity cell for flowing of the measured seawater, and the thermistor is packaged in the conductivity cell of the conductivity probe.
Furthermore, the temperature, salinity and depth sensor further comprises a control module for inhibiting the thermal hysteresis effect, the control module compares the temperature data measured by the platinum resistor and the thermistor, and selects a corresponding thermal hysteresis effect inhibition formula according to the temperature difference range obtained by comparison to obtain the actual conductivity near the thermistor, so that the error amplitude caused by the thermal hysteresis effect is corrected.
Further, the conductivity sensor also comprises a conductivity cylinder arranged on the end cover, and the conductivity probe is connected with the end cover through the conductivity cylinder; the platinum resistor and the pressure sensor are arranged on the end cover.
A method of controlling a thermohaline depth sensor to suppress thermal hysteresis effects, the method comprising:
(1) initializing and setting parameters of a temperature, salinity and depth sensor measurement control module;
(2) delaying for waiting, reading temperature data acquired by a platinum resistor on the end cover, filtering singular value median filtering processing on the temperature data acquired by the platinum resistor, and calculating by a quartic fitting formula to obtain a measured value T1 of the platinum resistor temperature;
(3) reading temperature data acquired by a thermistor packaged in the conductivity probe, filtering singular value median values of the temperature data acquired by the thermistor, and calculating by a quartic fitting formula to obtain a measured thermistor temperature value T2;
(4) subtracting the temperature measurement data T1 and T2, comparing, selecting a formula for inhibiting the thermal hysteresis effect according to the comparison result, and correcting the actual conductivity data measured by the conductivity probe, wherein the formula specifically comprises the following steps:
if the absolute value | T2-T1| ≧ T of the subtraction result1Correcting by using two parameters of abnormal relaxation time tau and sensitivity gamma by using a thermal hysteresis effect inhibiting formula;
if the absolute value t of the subtraction result2≤|T2-T1|≤t1Correcting by using a thermal hysteresis effect inhibition formula and using a parameter of abnormal relaxation time tau;
if the absolute value | T2-T1| of the subtraction result is less than or equal to T2Correcting without adopting a formula for inhibiting the thermal hysteresis effect;
wherein, t1And t2The two thresholds are determined according to different changes of sea thermocline of a specific application sea area of the temperature sensor or specific sea condition differences;
(5) delaying for waiting, starting an excitation source of a probe of the conductivity sensor, collecting conductivity data of the conductivity sensor, filtering singular value median filtering processing on the conductivity data, and calculating by a quartic fitting formula to obtain a conductivity measured value C; then closing an excitation source of the conductivity sensor probe;
(6) and (3) delaying for waiting, acquiring the measurement data of the pressure sensor, filtering the singular value median of the measurement data of the pressure sensor, performing four-time fitting formula calculation, and obtaining a pressure measured value D.
(7) And finishing a measuring period of the warm salt depth sensor.
Further, in the step (2), the step of filtering singular value median filtering of the temperature data collected by the platinum resistor means that the maximum value and the minimum value of analog-to-digital conversion voltage values of m original temperature data continuously measured by the platinum resistor are removed, and the arithmetic mean value v is obtained from the analog-to-digital conversion voltage values of the remaining m-2 temperature dataTWherein m is more than or equal to 3;
the four-term fitting formula calculation is carried out, and the formula for obtaining the measured value T1 of the platinum resistance temperature is as follows:
in the formula, a0、a1、a2、a3、a4Is a standard coefficient obtained by the platinum resistor according to the national standard GBT23246-2009 calibration test.
Further, in the step (3), the step of filtering the singular value median filter processing of the temperature data acquired by the thermistor means that the analog-to-digital conversion voltage values of o original temperature data continuously measured by the platinum resistor are removed from the maximum value and the minimum value, and the arithmetic mean value v is obtained from the analog-to-digital conversion voltage values of the remaining o-2 temperature dataW(ii) a Wherein o is more than or equal to 3;
the formula of the measured thermistor temperature value T2 is obtained by four times of fitting formula calculation:
in the formula, b0、b1、b2、b3、b4Is a standard coefficient obtained by the thermistor according to the national standard GBT23246-2009 calibration test.
Further, in the step (4),
when | T2-T1| ≧ T1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+γa[T(n)-T(n-1)]；
when t is reached2≤|T2-T1|≤t1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+a[T(n)-T(n-1)]
wherein, CT(n) is the actual conductivity value measured by the conductivity sensor for the current measurement period, CT(n-1) is an actual conductivity value measured by the conductivity sensor in the previous measuring period, T (n) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the current measuring period, and T (n-1) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the previous measuring period; γ is the sensitivity of the conductivity to temperature; n is the sampling count, a and b are both coefficients, and are calculated by the following formula:
a＝4fnαβ-1(1+4fnβ-1)-1；
b＝1-2aα-1；
α is the initial weighted fluid temperature error with a gradient of 1 deg.C, fnIs Nyquist frequency, tau is the abnormal relaxation time of the water surface temperature, beta is the reciprocal of tau; the coefficients a, b are determined from the temperature error a and the abnormal relaxation time τ values.
Further, in the step (5), the filtering of the singular value median filter processing on the conductivity data means that the conductivity sensor continuously measures the analog-to-digital conversion voltage values of p original conductivity data, removes the maximum value and the minimum value, and calculates the arithmetic mean value v of the analog-to-digital conversion voltage values of the remaining p-2 conductivity dataC；p≥3；
The formula of the measured value of the conductivity C obtained by the calculation of the fourth-order fitting formula is:
in the formula, c0、c1、c2、c3、c4The standard coefficient is obtained by a conductivity sensor probe according to a national standard GBT23246-2009 calibration test.
Further, in the step (6), the filtering of singular value median filtering processing on the measurement data of the pressure sensor means that the pressure sensor continuously measures the analog-to-digital conversion voltage values of q pieces of original pressure data, removes the maximum value and the minimum value, and calculates the arithmetic mean value v of the analog-to-digital conversion voltage values of the remaining q-2 pieces of pressure dataD；q≥3；
And (4) calculating by a four-term fitting formula to obtain a pressure measured value D:
in the formula (d)0、d1、d2、d3、d4The standard coefficient is obtained by the pressure sensor according to the national standard GBT23246-2009 calibration test.
Further, between the step (6) and the step (7), the following steps are also included:
after the step (6) is finished, inquiring whether a setting instruction of the serial port communication of the upper computer exists, and if the setting instruction of the serial port communication of the upper computer does not exist, directly entering the step (7) to finish the measuring period of the temperature and salt depth sensor for one time; if the communication command of the upper computer is received, the ASCII code of the communication protocol command is specifically analyzed:
if the first instruction is received, the excitation source of the conductivity sensor probe is closed;
if a second instruction is received, starting a probe excitation source of the conductivity sensor;
if a third instruction is received, the data output mode of the temperature, salinity and depth sensor is an output mode of jointly outputting the analog-to-digital conversion original voltage value and the measured value;
if a fourth instruction is received, the measurement data of the thermohaline depth sensor is in a normal output mode;
and if a fifth instruction is received, outputting the measurement data of the temperature, salinity and depth sensor and increasing the serial number.
If a sixth instruction is received, setting parameters such as thermal hysteresis effect correction of the thermohaline depth sensor, measurement time interval and the like;
after the ASCII code of the communication protocol instruction is specifically analyzed, the step (7) is carried out to finish the measuring period of the temperature, salt and depth sensor.
The invention has the beneficial technical effects that:
according to the method, a high-precision and quick-response temperature sensor is respectively integrated on the conductivity sensor and the end cover of the temperature and salt depth sensor; the temperatures measured by the two temperature sensors are compared, and whether an algorithm for inhibiting the thermal hysteresis effect is carried out or not is judged according to the magnitude and the range of the absolute value of the temperature difference, and a thermal hysteresis effect correction formula and a mathematical model are selected.
Drawings
FIG. 1 is a schematic structural diagram of a thermohaline depth sensor according to an embodiment of the present invention;
FIG. 2 is a flowchart of a method for controlling a thermohaline depth sensor with a thermal hysteresis effect suppression function according to an embodiment of the present invention;
reference numerals: 1. a conductivity cell; 2. a conductivity sensor probe; 3. a thermistor; 4. a conductivity sensor column; 5. a platinum resistor; 6. a pressure sensor; 7. an end cap; 8. a pressure-resistant cabin body.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
The invention discloses a control method for inhibiting a thermal hysteresis effect by a temperature, salt and depth sensor, and relates to a software control flow and an algorithm for measuring marine hydrokinetic parameters by a novel profile suitable for an underwater autonomous mobile observation platform. The method comprises the steps of comparing data with a reference temperature sensor integrated with a conductivity sensor and a measurement temperature sensor integrated with a temperature-salt-depth sensor end cover, and selecting a method for inhibiting a thermal hysteresis effect formula according to a difference range to obtain the actual conductivity near the reference temperature sensor, so that the error amplitude caused by the thermal hysteresis effect is corrected. The method can obviously improve the precision of the measured data when the underwater autonomous mobile observation platform carries the thermohaline depth sensor to pass through the thermocline, thereby making up the defects of the existing related thermohaline depth profile measuring technology. The thermohaline depth sensor has the working capacity of long-term online and self-contained measurement, can be applied to observation platforms of underwater robots, underwater gliders and manned deep submersible operation devices, and has important significance in improving the data quality of acquired marine hydrodynamic parameters.
An embodiment of the present invention provides a temperature and salt depth sensor, as shown in fig. 1, including: the pressure-resistant cabin comprises a pressure-resistant cabin body, an end cover arranged on the pressure-resistant cabin body, a platinum resistor, a pressure sensor and a conductivity sensor;
the conductivity sensor comprises a conductivity probe and a thermistor, the conductivity probe comprises a through hole-shaped conductivity cell for flowing of the measured seawater, and the thermistor is packaged in the conductivity cell of the conductivity probe.
Specifically, a hole is formed in the internal cross section of the conductivity cell, and the thermistor probe is packaged and sealed in the hole. The cross section inside the conductivity cell refers to the middle position of the inner arc surface of a cylindrical through hole (namely the conductivity cell) of the conductivity probe, a hole is formed in the cross section inside the conductivity cell for tapping, the thermistor probe is screwed tightly through threads, an O-shaped ring is used for sealing, and sealing silicone grease is filled in the hole.
In this embodiment, the temperature, salinity and depth sensor further includes a control module for suppressing a thermal hysteresis effect, the control module compares temperature data measured by the platinum resistor and the thermistor, and selects a corresponding thermal hysteresis effect suppression formula according to a temperature difference range obtained by the comparison to obtain an actual conductivity near the thermistor, thereby correcting an error amplitude caused by the thermal hysteresis effect.
In this embodiment, the conductivity sensor further includes a conductivity cylinder disposed on the end cap, and the conductivity probe is connected to the end cap through the conductivity cylinder; the platinum resistor and the pressure sensor are arranged on the end cover.
Preferably, the platinum resistor adopts Pt1000 with high precision and quick response.
Preferably, the thermistor adopts a high-precision and quick-response NTC thermistor.
The invention also provides an embodiment of a control method of the thermohaline depth sensor for inhibiting the thermal hysteresis effect, and the thermohaline depth sensor adopting the embodiment comprises the following steps:
(1) initializing and setting parameters of a temperature, salinity and depth sensor measurement control module; preferably, the parameters include serial port communication parameters, analog-to-digital conversion acquisition parameters, general IO port parameters, watchdog parameters, and interrupt parameters;
(2) delaying for waiting, reading temperature data acquired by a platinum resistor on the end cover, filtering singular value median filtering processing on the temperature data acquired by the platinum resistor, and calculating by a quartic fitting formula to obtain a measured value T1 of the platinum resistor temperature;
(3) reading temperature data acquired by a thermistor packaged in the conductivity probe, filtering singular value median values of the temperature data acquired by the thermistor, and calculating by a quartic fitting formula to obtain a measured thermistor temperature value T2;
(4) subtracting the temperature measurement data T1 from the temperature measurement data T2, comparing, and selecting a thermal hysteresis effect inhibition formula according to the comparison result to correct the actual conductivity data measured by the conductivity probe, wherein the specific steps are as follows:
if the result of the subtraction is positiveAbsolute value of | T2-T1| ≧ T1Correcting by using two parameters of abnormal relaxation time tau and sensitivity gamma by using a thermal hysteresis effect inhibiting formula;
if the absolute value t of the subtraction result2≤|T2-T1|≤t1Correcting by using a thermal hysteresis effect inhibition formula and using a parameter of abnormal relaxation time tau;
if the absolute value | T2-T1| of the subtraction result is less than or equal to T2Correcting without adopting a formula for inhibiting the thermal hysteresis effect;
wherein, t1And t2The two thresholds are determined according to different changes of sea thermocline of a specific application sea area of the temperature sensor or specific sea condition differences; for example, in the sea area of 21 degrees north latitude and 118 degrees east longitude in the south sea, a plurality of high-performance temperature and salt depth sensors with different models are adopted, and through comparison and analysis of a large amount of sea test data for a long time, an obvious thermocline exists in the water depth of 100-200 meters. The error amplitude of the temperature sensor with fast response is less than or equal to 0.05 ℃, and the error amplitude of the temperature sensor with slow response time is less than or equal to 0.1 ℃. Therefore, in a specific thermocline with the water depth of 100-200 m in a specific sea area of 21 degrees north latitude and 118 degrees east longitude in the south sea, t is set1＝0.1℃，t20.05 ℃. It should be noted that different thermocline t in a specific sea area is determined1And t2And a plurality of high-performance temperature and salinity depth sensors with different models are adopted for the two thresholds, a large number of sea tests are carried out in the same sea area at different time, and the sea test data are compared and statistically analyzed.
(5) Delaying for waiting, starting an excitation source of a probe of the conductivity sensor, collecting conductivity data of the conductivity sensor, filtering singular value median filtering processing on the conductivity data, and calculating by a quartic fitting formula to obtain a conductivity measured value C; then closing an excitation source of the conductivity sensor probe; so as to reduce the power consumption of the temperature, salinity and depth sensor;
(6) and (3) delaying for waiting, acquiring the measurement data of the pressure sensor, filtering the singular value median of the measurement data of the pressure sensor, performing four-time fitting formula calculation, and obtaining a pressure measured value D.
(7) And finishing a measuring period of the warm salt depth sensor.
In step (2) of this embodiment, the filtering of singular value median filtering processing on the temperature data collected by the platinum resistor means that the maximum value and the minimum value of the analog-to-digital conversion voltage values of m original temperature data continuously measured by the platinum resistor are removed, and the arithmetic mean value v is obtained from the analog-to-digital conversion voltage values of the remaining m-2 temperature dataTWherein m is more than or equal to 3; preferably, m is 11.
The four-term fitting formula calculation is carried out, and the formula for obtaining the measured value T1 of the platinum resistance temperature is as follows:
in the formula, a0、a1、a2、a3、a4Is a standard coefficient obtained by a platinum resistor calibration test according to the national standard (GBT23246-2009 conductivity temperature depth profiler).
In step (3) of this embodiment, the step of filtering the singular value median filter from the temperature data collected by the thermistor refers to the step of obtaining an arithmetic mean value v from the analog-to-digital conversion voltage values of o original temperature data continuously measured by the platinum resistor, removing the maximum value and the minimum value, and obtaining the analog-to-digital conversion voltage values of the remaining o-2 temperature dataW(ii) a Wherein o is more than or equal to 3; preferably, o ═ 11;
the formula of the measured thermistor temperature value T2 is obtained by four times of fitting formula calculation:
in the formula, b0、b1、b2、b3、b4The standard coefficient is obtained by the thermistor according to the national standard (GBT23246-2009 conductivity temperature depth profiler) calibration test.
In the step (4) of the present embodiment,
when | T2-T1| ≧ T1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+γa[T(n)-T(n-1)]；
when t is2≤|T2-T1|≤t1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+a[T(n)-T(n-1)]
wherein, CT(n) is the actual conductivity value measured by the conductivity sensor for the current measurement period, CT(n-1) is an actual conductivity value measured by the conductivity sensor in the previous measuring period, T (n) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the current measuring period, and T (n-1) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the previous measuring period; γ is the sensitivity of the conductivity to temperature; n is the sampling count, a and b are both coefficients, and are calculated by the following formula:
a＝4fnαβ-1(1+4fnβ-1)-1；
b＝1-2aα-1；
α is the initial weighted fluid temperature error with a gradient of 1 deg.C, fnIs the Nyquist frequency, τ is the abnormal relaxation time of the water surface temperature, and β is the reciprocal of τ; the coefficients a, b are determined from the temperature error a and the abnormal relaxation time τ values.
In step (5) of this embodiment, the filtering of the singular value median of the conductivity data refers to that the conductivity sensor continuously measures the analog-to-digital conversion voltage values of p pieces of original conductivity data, removes the maximum value and the minimum value, and calculates the arithmetic mean v from the analog-to-digital conversion voltage values of the remaining p-2 pieces of conductivity dataC(ii) a p is more than or equal to 3; preferably, p is equal to 11.
The formula of the measured value of the conductivity C obtained by the calculation of the fourth-order fitting formula is:
in the formula, c0、c1、c2、c3、c4The conductivity sensor probe is according to national standard (GBT23246-2009 electricity)Conductivity temperature depth profiler) to calibrate the standard coefficients obtained by the test.
In step (6) of this embodiment, the filtering of singular value median filter processing on the measurement data of the pressure sensor means that the pressure sensor continuously measures the analog-to-digital conversion voltage values of q pieces of original pressure data, removes the maximum value and the minimum value, and calculates the arithmetic mean value v from the analog-to-digital conversion voltage values of the remaining q-2 pieces of pressure dataD(ii) a q is more than or equal to 3; preferably, q is equal to 11.
And (4) calculating by a four-term fitting formula to obtain a pressure measured value D:
in the formula (d)0、d1、d2、d3、d4The standard coefficient is obtained by the pressure sensor according to the national standard (GBT 23246-.
In this embodiment, between step (6) and step (7), the following steps are further included:
after the step (6) is finished, inquiring whether a setting instruction of the serial port communication of the upper computer exists, and if the setting instruction of the serial port communication of the upper computer does not exist, directly entering the step (7) to finish the measuring period of the temperature and salt depth sensor for one time; if the communication command of the upper computer is received, the ASCII code of the communication protocol command is specifically analyzed:
if the first instruction is received, the excitation source of the conductivity sensor probe is closed;
if a second instruction is received, starting a probe excitation source of the conductivity sensor;
if a third instruction is received, the data output mode of the temperature, salinity and depth sensor is an output mode of jointly outputting the analog-to-digital conversion original voltage value and the measured value;
if a fourth instruction is received, the measurement data of the thermohaline depth sensor is in a normal output mode;
and if a fifth instruction is received, outputting the measurement data of the temperature, salinity and depth sensor and increasing the serial number.
If a sixth instruction is received, setting parameters such as thermal hysteresis effect correction of the thermohaline depth sensor, measurement time interval and the like;
after the ASCII code of the communication protocol instruction is specifically analyzed, the step (7) is carried out to finish the measuring period of the temperature, salt and depth sensor.
Technical contents not described in the above embodiments can be realized by taking or referring to the existing technologies.
The control method of the temperature-salinity-depth sensor for inhibiting the thermal hysteresis effect can also be widely applied to general marine monitoring and investigation and research work, and provides accurate temperature-salinity-depth and other basic hydrographic dynamic parameters for deep sea research.
Compared with the prior art, the invention has the beneficial technical effects that:
the method can modify the abnormal relaxation time tau or the inverse beta of the thermal hysteresis effect correction formula seawater surface temperature, and can weigh the main parameters such as the fluid temperature error alpha and the sensitivity gamma of the conductivity to the temperature with the initial gradient of 1 ℃ through the serial port communication instruction of the upper computer.
The invention discloses a control method for inhibiting a thermal hysteresis effect by a temperature, salt and depth sensor, and relates to a software control flow and an algorithm for measuring marine hydrokinetic parameters by a novel profile suitable for an underwater autonomous mobile observation platform. The method comprises the steps of comparing data (platinum resistance) with a reference temperature sensor (a thermistor in a conductivity sensor probe) integrated with a temperature sensor integrated with a temperature-salt-depth sensor end cover, selecting a method for inhibiting a thermal hysteresis effect formula according to a difference range, so as to obtain the actual conductivity near the reference temperature sensor, and correcting the error amplitude caused by the thermal hysteresis effect. The method can obviously improve the precision of the measured data when the underwater autonomous mobile observation platform carries the thermohaline depth sensor to pass through the thermocline, thereby making up the defects of the existing related thermohaline depth profile measuring technology and improving the measurement precision of the thermohaline depth sensor on the temperature and salinity under the autonomous mobile observation application environment. The thermohaline depth sensor has the working capacity of long-term online and self-contained measurement, can be applied to observation platforms of underwater robots, underwater gliders and manned deep submersible operation devices, and has important significance in improving the data quality of acquired marine hydrodynamic parameters.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (8)
1. A thermohaline depth sensor, comprising: the pressure-resistant cabin comprises a pressure-resistant cabin body, an end cover arranged on the pressure-resistant cabin body, a platinum resistor, a pressure sensor and a conductivity sensor;
the conductivity sensor comprises a conductivity probe and a thermistor, the conductivity probe comprises a through-hole-shaped conductivity cell for flowing of the measured seawater, and the thermistor is packaged in the conductivity cell of the conductivity probe;
the temperature, salinity and depth sensor also comprises a control module for inhibiting the thermal hysteresis effect, the control module compares the temperature data measured by the platinum resistor and the thermistor, and selects a corresponding formula for inhibiting the thermal hysteresis effect according to the temperature difference range obtained by comparison so as to obtain the actual conductivity near the thermistor, thereby realizing the correction of the error amplitude caused by the thermal hysteresis effect;
the conductivity sensor also comprises a conductivity cylinder arranged on the end cover, and the conductivity probe is connected with the end cover through the conductivity cylinder; the platinum resistor and the pressure sensor are arranged on the end cover.
2. A method of controlling a thermohaline depth sensor according to claim 1, the method comprising:
(1) initializing and setting parameters of a temperature, salinity and depth sensor measurement control module;
(2) delaying for waiting, reading temperature data acquired by a platinum resistor on the end cover, filtering singular value median filtering processing on the temperature data acquired by the platinum resistor, and calculating by a quartic fitting formula to obtain a measured value T1 of the platinum resistor temperature;
(3) reading temperature data acquired by a thermistor packaged in the conductivity probe, filtering singular value median values of the temperature data acquired by the thermistor, and calculating by a quartic fitting formula to obtain a measured thermistor temperature value T2;
(4) subtracting the temperature measurement data T1 and T2, comparing, selecting a formula for inhibiting the thermal hysteresis effect according to the comparison result, and correcting the actual conductivity data measured by the conductivity probe, wherein the formula specifically comprises the following steps:
if the absolute value | T2-T1| ≧ T of the subtraction result1Correcting by using two parameters of abnormal relaxation time tau and sensitivity gamma by using a thermal hysteresis effect inhibiting formula;
if the absolute value t of the subtraction result2≤|T2-T1|≤t1Correcting by using a thermal hysteresis effect inhibition formula and using a parameter of abnormal relaxation time tau;
if the absolute value | T2-T1| of the subtraction result is less than or equal to T2Correcting without adopting a formula for inhibiting the thermal hysteresis effect;
wherein, t1And t2The two thresholds are determined according to different changes of sea thermocline of a specific application sea area of the temperature sensor or specific sea condition differences;
(5) delaying for waiting, starting an excitation source of a probe of the conductivity sensor, collecting conductivity data of the conductivity sensor, filtering singular value median filtering processing on the conductivity data, and calculating by a quartic fitting formula to obtain a conductivity measured value C; then closing an excitation source of the conductivity sensor probe;
(6) delaying for waiting, acquiring the measurement data of the pressure sensor, filtering the singular value median of the measurement data of the pressure sensor, and calculating by a quartic fitting formula to obtain a pressure measured value D;
(7) and finishing a measuring period of the warm salt depth sensor.
3. The method for controlling a thermohaline depth sensor according to claim 2, characterized in that in the step (2), the step of filtering singular value median filter processing of the temperature data collected by the platinum resistor means that the platinum resistor is continuously measured for mThe analog-to-digital conversion voltage value of the original temperature data is removed from the maximum value and the minimum value, and the arithmetic mean value v is obtained from the analog-to-digital conversion voltage values of the remaining m-2 temperature dataTWherein m is more than or equal to 3;
the four-term fitting formula calculation is carried out, and the formula for obtaining the measured value T1 of the platinum resistance temperature is as follows:
in the formula, a0、a1、a2、a3、a4Is a standard coefficient obtained by the platinum resistor according to the national standard GBT23246-2009 calibration test.
4. The method for controlling the thermohaline depth sensor according to claim 2, wherein in the step (3), the step of filtering the singular value median filter processing of the temperature data collected by the thermistor means that the analog-to-digital conversion voltage values of o original temperature data continuously measured by the platinum resistor are removed from the maximum value and the minimum value, and the arithmetic mean value v is obtained from the analog-to-digital conversion voltage values of the remaining o-2 temperature dataW(ii) a Wherein o is more than or equal to 3;
the formula of the measured thermistor temperature value T2 is obtained by four times of fitting formula calculation:
in the formula, b0、b1、b2、b3、b4Is a standard coefficient obtained by the thermistor according to the national standard GBT23246-2009 calibration test.
5. The method for controlling a thermohaline depth sensor according to claim 2, wherein in step (4),
when | T2-T1| ≧ T1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+γa[T(n)-T(n-1)]；
when t is2≤|T2-T1|≤t1In the process, the calculation formula of the actual conductivity value measured by the conductivity sensor is as follows:
CT(n)＝-bCT(n-1)+a[T(n)-T(n-1)]
wherein, CT(n) is the actual conductivity value measured by the conductivity sensor for the current measurement period, CT(n-1) is an actual conductivity value measured by the conductivity sensor in the previous measuring period, T (n) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the current measuring period, and T (n-1) is an actual temperature value measured by the thermistor integrated in the conductivity probe in the previous measuring period; γ is the sensitivity of the conductivity to temperature; n is the sampling count, a and b are both coefficients, and are calculated by the following formula:
a＝4fnαβ-1(1+4fnβ-1)-1；
b＝1-2aα-1；
α is the initial weighted fluid temperature error with a gradient of 1 deg.C, fnIs Nyquist frequency, tau is the abnormal relaxation time of the water surface temperature, beta is the reciprocal of tau; the coefficients a, b are determined from the temperature error a and the abnormal relaxation time τ values.
6. The method for controlling a thermohaline depth sensor according to claim 2, wherein in the step (5), the filtering of singular value median filtering processing on the conductivity data means that the conductivity sensor continuously measures the analog-to-digital conversion voltage values of p original conductivity data, removes the maximum value and the minimum value, and calculates the arithmetic mean value v of the analog-to-digital conversion voltage values of the remaining p-2 conductivity dataC；p≥3；
The formula of the measured value of the conductivity C obtained by the calculation of the fourth-order fitting formula is:
in the formula, c0、c1、c2、c3、c4The standard coefficient is obtained by a conductivity sensor probe according to a national standard GBT23246-2009 calibration test.
7. The method for controlling the thermohaline depth sensor according to claim 2, wherein in the step (6), the filtering of singular value median filter processing on the measurement data of the pressure sensor means that the pressure sensor continuously measures the analog-to-digital conversion voltage values of q original pressure data, the maximum value and the minimum value are removed, and the arithmetic mean v is obtained by the analog-to-digital conversion voltage values of the remaining q-2 pressure dataD；q≥3；
And (4) calculating by a four-term fitting formula to obtain a pressure measured value D:
in the formula (d)0、d1、d2、d3、d4The standard coefficient is obtained by the pressure sensor according to the national standard GBT23246-2009 calibration test.
8. The method for controlling the thermohaline depth sensor according to claim 2, characterized by further comprising the following steps between the step (6) and the step (7):
after the step (6) is finished, inquiring whether a setting instruction of the serial port communication of the upper computer exists, and if the setting instruction of the serial port communication of the upper computer does not exist, directly entering the step (7) to finish the measuring period of the temperature and salt depth sensor for one time; if the communication command of the upper computer is received, the ASCII code of the communication protocol command is specifically analyzed:
if the first instruction is received, the excitation source of the conductivity sensor probe is closed;
if a second instruction is received, starting a probe excitation source of the conductivity sensor;
if a third instruction is received, the data output mode of the temperature, salinity and depth sensor is an output mode in which the analog-to-digital conversion original voltage value and the measured value are output together;
if a fourth instruction is received, the measurement data of the thermohaline depth sensor is in a normal output mode;
if a fifth instruction is received, outputting the measurement data of the thermohaline depth sensor and increasing the serial number;
if a sixth instruction is received, setting thermal hysteresis effect correction of the thermohaline depth sensor, and measuring a time interval;
after the ASCII code of the communication protocol instruction is specifically analyzed, the step (7) is carried out to finish the measuring period of the temperature, salt and depth sensor.
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