# US 2018/0321071 A1 · Liquid level sensing and diagnostic determination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321071 A1 - Document ID: US20180321071A1 - Status: Published application - Kind: A1 - Application number: 15/584,514 - Filed: 2017-05-02 - Published: 2018-11-08 - Earliest claimed: 2017-05-02 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: John F. Larsen - Web page: https://patentgrep.com/patent/US20180321071A1 ## CPC - G01F 23/802: {Particular electronic circuits for digital processing equipment} - B60K 15/00: Arrangement in connection with fuel supply of combustion engines {or other fuel consuming energy converters, e.g. fuel cells}; Mounting or construction of fuel tanks - B60K 15/03: Fuel tanks - G01F 23/22: by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water (involving the use of floats G01F23/30) - G01F 25/20: of apparatus for measuring liquid level - G01N 35/1009: {Characterised by arrangements for controlling the aspiration or dispense of liquids} - G05D 9/12: characterised by the use of electric means - G06Q 10/0631: Resource planning, allocation, distributing or scheduling for enterprises or organisations - B60K 2015/03217: {Fuel level sensors} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES - G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR ## Abstract A method for determining a liquid level of a reservoir includes sensing a plurality of liquid level points during a plurality of defined computation intervals, and determining filtered block points from the sensed liquid level points occurring during each of the computation intervals. The method fits a regression model to the determined filtered block points, including determining a slope and a standard error of regression, and determines an actual liquid level change from the slope of the regression model. The method may also include making a diagnostic determination if the method determines that a confidence ratio is sufficiently high. ## Claims ### Claim 1 A method for determining a liquid level change of a reservoir subject to disturbances, the method comprising: sensing a plurality of liquid level points during a plurality of defined computation intervals; determining a plurality of filtered block points from the sensed liquid level points occurring during each of the computation intervals; fitting a regression model to the determined filtered block points, including determining a slope and a standard error of regression; and determining an actual liquid level change from the slope of the regression model. ### Claim 2 (depends on 1) The method of claim 1, further comprising: monitoring an inflow and an outflow from the reservoir; determining an expected liquid level change from the inflow and the outflow; calculating a potential level error from the difference between the expected liquid level change and the actual liquid level change; determining a confidence ratio from the standard error of regression of the regression model; and comparing the determined confidence ratio to a minimum confidence ratio: if the determined confidence ratio is higher than the minimum confidence ratio, making a diagnostic determination from the potential level error; and if the determined confidence ratio is lower than the minimum confidence ratio, making no diagnostic determination, irrespective of the potential level error. ### Claim 3 (depends on 2) The method of claim 2, wherein the computation intervals are defined by a parameter that is proportional to the actual liquid level change. ### Claim 4 (depends on 2) The method of claim 2, wherein the computation intervals are defined by net liquid transferred to and from the reservoir. ### Claim 5 (depends on 2) The method of claim 2, wherein the filtered block points are calculated as an arithmetic mean of the sensed liquid level points over each of the computation intervals. ### Claim 6 (depends on 2) The method of claim 2, wherein the filtered block points are calculated as an exponentially weighted moving average of the sensed liquid level points over each of the computation intervals. ### Claim 7 (depends on 2) The method of claim 2, wherein the regression model is an ordinary least squares (OLS) model. ### Claim 8 (depends on 2) The method of claim 2, wherein, if the determined confidence ratio is higher than the minimum confidence ratio, making the diagnostic determination includes: determining a total variation from at least the standard error of regression multiplied by a calibrated factor; determining a lower failure threshold by subtracting the total variation from the expected liquid level change; and comparing the actual liquid level change to the lower failure threshold: if the actual liquid level change is less than the lower failure threshold, recording a diagnostic failure; and if the actual liquid level change is greater than the lower failure threshold, recording a diagnostic pass. ### Claim 9 (depends on 8) The method of claim 8, wherein making the diagnostic determination further includes: determining an upper failure threshold by adding the total variation to the expected liquid level change; and comparing the actual liquid level change to the upper failure threshold: if the actual liquid level change is greater than the upper failure threshold, recording a diagnostic failure; and if the actual liquid level change is greater than the lower failure threshold and less than the upper failure threshold, recording a diagnostic pass. ### Claim 10 (depends on 9) The method of claim 9, wherein the computation intervals are defined by a parameter that is proportional to the actual liquid level change; and wherein the regression model is a linear model. ### Claim 11 (depends on 10) The method of claim 10, further comprising: comparing the number of the filtered block points to a minimum regression sample size; and determining the confidence ratio only if the number of the number of the filtered block points is greater than or equal to the minimum regression sample size. ### Claim 12 A method for determining a liquid level of a reservoir subject to disturbances, the method comprising: sensing a plurality of liquid level points during a plurality of defined computation intervals; determining a plurality of filtered block points from the sensed liquid level points occurring during each of the computation intervals; fitting a regression model to the determined filtered block points, including determining a slope and a standard error of regression; and determining an actual liquid level from the slope of the regression model. ### Claim 13 (depends on 12) The method of claim 12, further comprising: monitoring an inflow and an outflow from the reservoir; determining an expected liquid level from the inflow and the outflow; calculating a potential level error from the difference between the expected liquid level and the actual liquid level; determining a confidence ratio from the standard error of regression of the regression model; and comparing the determined confidence ratio to a minimum confidence ratio: if the determined confidence ratio is higher than the minimum confidence ratio, making a diagnostic determination from the potential level error; and if the determined confidence ratio is lower than the minimum confidence ratio, making no diagnostic determination, irrespective of the potential level error. ### Claim 14 (depends on 13) The method of claim 13, wherein, if the determined confidence ratio is higher than the minimum confidence ratio, making the diagnostic determination includes: determining a total variation from at least the standard error of regression multiplied by a calibrated factor; determining a lower failure threshold by subtracting the total variation from the expected liquid level; and comparing the actual liquid level to the lower failure threshold: if the actual liquid level is less than the lower failure threshold, recording a diagnostic failure; and if the actual liquid level is greater than the lower failure threshold, recording a diagnostic pass. ### Claim 15 (depends on 14) The method of claim 14, wherein the computation intervals are defined by a parameter that is proportional to the actual liquid level; and wherein the regression model is a linear model. ### Claim 16 (depends on 15) The method of claim 15, wherein the regression model is an ordinary least squares (OLS) model.