# US 2009/0260414 A1 · Method of calibrating measurement systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260414 A1 - Document ID: US20090260414A1 - Status: Published application - Kind: A1 - Application number: 12/094,821 - Filed: 2005-11-23 - Published: 2009-10-22 - Earliest claimed: 2005-11-23 - Assignees: AB Volvo Penta - Inventors: Pal Loodberg - Web page: https://patentgrep.com/patent/US20090260414A1 ## CPC - G01F 25/20: of apparatus for measuring liquid level - B63B 11/04: Constructional features of bunkers, {e.g. structural fuel tanks,} or ballast tanks, e.g. with elastic walls ({tanks for fuel or the like not forming subdivisions of the hull B63B17/0027; } cleaning of tanks B63B57/00) - G01F 23/30: by floats - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - B63B: SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING (arrangements of vessel ventilation, heating, cooling, or air-conditioning B63J2/00; floating substructures as supports of dredgers or soil-shifting machines E02F9/06) ## Abstract There is provided a method of calibrating a measurement system for measuring a position (h) of a meniscus of a liquid fuel included within a marine fuel tank and therefrom generating a corresponding content signal indicative of a proportion of the tank filled with fuel. The method includes steps of: (a) from a first time instance when the tank is substantially empty, filling during a calibration phase the tank with the fuel at a substantially constant rate whilst simultaneously recording corresponding values (h(t)) of a meniscus position indicative signal generated by the measurement system; (b) at a second time instance after said first time instance, terminating filling of the tank with fuel when the position indicative signal corresponds to the tank being substantially filled with fuel; and (c) subsequently, after the calibration phase, applying signal processing to the position indicative signal to generate the content signal indicative of the proportion of the tank filled with fuel, the signal processing accounting for the tank during the calibration phase being filled at the substantially constant rate. ## Claims ### Claim 1 A method of calibrating a measurement system operable to measure a spatial position of a meniscus of a liquid included within a container and therefrom generating a corresponding liquid content signal indicative of a proportion of the container filled with the liquid, the method including steps of: (a) from a first time instance when the container is in a first state including a first quantity of the liquid, progressively filling during a calibration phase the container with the liquid at a substantially constant volumetric rate, which rate is unknown, of liquid delivery whilst periodically simultaneously recording corresponding generated values of a meniscus position indicative signal generated by the measurement system; (b) at a second time instance after the first time instance during the calibration phase, terminating progressive filling of the container with the liquid when the position indicative signal corresponds to the container being in a second state including a second quantity of the liquid; and (c) determining the position of the meniscus at a lower and upper position over which calibration is desired and/or a given volumetric capacity K of the container corresponding to the meniscus being at an upper position, for example at the second state; and (d) subsequently, in normal use after the calibration phase, applying signal processing to the position indicative signal provided from the measurement system to generate the corresponding liquid content signal indicative of the proportion of the container filled with the liquid, the signal processing accounting for the container during the calibration phase having been filled at the substantially constant volumetric rate of liquid delivery to the container. ### Claim 2 (depends on 1) A method as claimed in claim 1, wherein the first state corresponds to the tank being substantially empty and devoid of liquid therein, and the second state corresponding to the tank being in a full state substantially filled with liquid. ### Claim 3 (depends on 1) A method as claimed in claim 1, wherein the container is a fuel tank, and the liquid is a combustible fuel for including in the fuel tank. ### Claim 4 (depends on 1) A method as claimed in claim 1, wherein the measurement system operable to measure the spatial position of the meniscus of the liquid included in the container is operable to employ a float which is operable to float on the meniscus for measuring the position. ### Claim 5 (depends on 1) A method as claimed in claim 1, wherein in the step (c) the signal processing is implemented in a processor operable to determine a mathematical relationship between a volumetric portion of the container filled with liquid and the corresponding meniscus position indicative signal and to apply substantially the mathematical relationship so as to derive in the normal use the container liquid content signal indicative of a proportion of the container filled with the liquid. ### Claim 6 (depends on 5) A method as claimed in claim 5, wherein the mathematical relationship is a polynomial approximation derived from periodically recorded generated values of the meniscus position indicative signal. ### Claim 7 (depends on 1) A method as claimed in claim 1 adapted for use with a marine vessel wherein the container is a fuel tank of said the marine vessel. ### Claim 8 (depends on 1) A method as claimed in claim 1, wherein the container is a fuel tank arrangement susceptible to being supplemented with one or more additional fuel tanks in liquid communication with the fuel tank arrangement, the method being repeatedly applicable in response to the fuel tank arrangement being supplemented or desupplemented with the one or more additional tanks, so that the container liquid content signal is indicative of a proportion of the fuel tank arrangement and its one or more supplementary fuel tanks coupled thereto that are filled with the liquid. ### Claim 9 (depends on 1) A method as claimed in claim 1, wherein the first time instance is recorded by the measurement system as commencing when a threshold rate of change of the meniscus position indicative signal occurs after user activation of a calibrate input of the measurement system. ### Claim 10 A measurement system operable to measure a spatial position of a meniscus of a liquid included within a container and therefrom generating a corresponding liquid content signal indicative of a proportion of the container filled with the liquid, the measurement system being operable to being calibrated: (a) from a first time instance when said container is in a first state including a first quantity of liquid by progressively filling during a calibration phase said container with the liquid at a substantially constant rate, which rate is unknown, of liquid delivery whilst simultaneously recording corresponding generated values of a meniscus position indicative signal generated by said measurement system; (b) at a second time instance after said first time instance during said calibration phase, by terminating progressive filling of said container with said liquid when said position indicative signal corresponds to the container being in a second state including a second quantity of liquid, (c) determine the position of the meniscus at a lower and upper position over which calibration desired and/or a given volumetric capacity K of the container corresponding to the meniscus being at an upper position, for example at the second state; and (d) subsequently, in normal use after said calibration phase, by applying signal processing to said position indicative signal provided from the measurement system to generate said corresponding liquid content signal indicative of said proportion of the container filled with the liquid, said signal processing accounting for said container during said calibration phase having been filled at the substantially constant rate of liquid delivery to the container. ### Claim 11 (depends on 10) A measurement system as claimed in claim 10, wherein said first state corresponds to the container being substantially in an empty state substantially devoid of the liquid, and the second state corresponds to the container being in a full state substantially filled with the liquid. ### Claim 12 (depends on 11) A measurement system as claimed in claim 11, wherein the container is a fuel tank and the liquid is a combustible fuel, the measurement system being adapted to measure fuel included within the fuel tank. ### Claim 13 (depends on 11) A measurement system as claimed in claim 11 adapted for use in marine vessels. ### Claim 14 (depends on 1) Software on a data carrier, the software being executable on computing hardware for implementing a method as claimed in claim 1.