# US 2018/0321364 A1 · Method for Calibrating Measuring Element, Method for Evaluating Road Surface Properties, and Apparatus for Evaluating Road Surface Properties > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321364 A1 - Document ID: US20180321364A1 - Status: Published application - Kind: A1 - Application number: 15/850,212 - Filed: 2017-12-21 - Published: 2018-11-08 - Earliest claimed: 2017-03-01 - Assignees: Topcon Corporation - Applicants: Topcon Corporation - Inventors: You SASAKI; Tadayuki ITO - Web page: https://patentgrep.com/patent/US20180321364A1 ## CPC - G01S 7/497: Means for monitoring or calibrating - G01B 11/24: for measuring contours or curvatures - G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) - G01S 17/89: for mapping or imaging - G01S 7/4815: {using multiple transmitters} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract A method for calibrating unevenness of a plurally of measuring elements in an apparatus for evaluating road surface property having a plurality of measuring elements repeats steps of computing separation quantities from a calibration reference plane on a reference area regarding all measuring elements: determining a measuring element where the separation quantity is maximum from among all the measuring element to calibrate the measuring element such that a difference between point cloud data produced from a measurement value of the measuring element where the separation quantity is maximum and the calibration reference plane becomes equal or less than a predetermined value, producing a new calibration reference plane from the measurement values of the measuring elements including the calibrated measuring element, until RMS of point cloud data does not change. ## Claims ### Claim 1 A method for calibrating unevenness of a plurality of measuring elements in an apparatus for evaluating road surface properties the apparatus being provided with the plurality of measuring elements for emitting measuring light and receiving reflected light, the apparatus performing evaluation by scanning a road surface with the plurality of measuring elements and measuring a separation quantity from a reference plane of the road surface while being moved along a measurement route of the road surface, the method determining a final calibration value of each of the measuring elements by performing the steps of: setting a reference area for performing the calibration and a provisional reference plane of the reference area; acquiring a measurement value obtained by each of the measuring elements regarding the reference area; and producing point cloud data on separation quantity of the each point from the provisional reference plane of the reference area in the reference area and subsequently, until separation quantities form the reference plane for calibration of the point cloud data obtained by all the measuring elements become smaller than a predetermined reference value, repeating steps of: computing the separation quantities form the reference plane for calibration based upon the statistic regarding all of the measuring elements; determining a measuring element where the separation quantity is maximum from among all of the measuring elements, and determining a calibration value of the measuring element such that a difference between point cloud data produced form the measurement value of the measuring element where the separation quantity is maximum and the reference plane for calibration is equal to or less than a predetermined threshold; and producing a new reference plane for calibration form the measurement values of all of the measuring elements including the measuring element calibrated. ### Claim 2 (depends on 1) The method for calibrating unevenness of a plurality of measuring elements in an apparatus for evaluating road surface properties according to claim 1, wherein, when the provisional reference plane of the reference area is set, it is confirmed that a separation quantity at each measuring point from a fitting plane produced from measurement values acquired in the reference area measured by one measuring element selected from the plurality of measuring elements is smaller than a predetermined specified value. ### Claim 3 (depends on 1) The method for calibrating unevenness of a plurality of measuring elements in an apparatus for evaluating road surface properties according to claim 1, wherein the reference area is set at a specified place in the measurement route of the road surface to be measured. ### Claim 4 (depends on 1) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 1, wherein the reference area is set at least one of a place corresponding to a starting position of the measurement route and a place corresponding to a terminating position thereof. ### Claim 5 (depends on 4) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 4, wherein the reference area is set at two places corresponding to a starting position and corresponding to a terminating position, and a calibration value of each measuring element at each measuring point between the place corresponding to a starting position to the place corresponding and a terminating position is acquired based upon the calibration value of each measuring element acquired at the two positions. ### Claim 6 (depends on 1) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 1, wherein a flat plate is disposed on the reference area. ### Claim 7 (depends on 1) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 1, wherein each measuring element is calibrated based upon the calibration value to perform evaluation of the road surface and the road surface properties. ### Claim 8 An apparatus for evaluating road surface properties provided with a plurality of measuring, elements emitting measuring light and receiving reflected light for performing evaluation by scanning a road surface by the plurality of measuring elements and measuring a separation quantity from a reference plane of the road surface while the apparatus for evaluating road surface properties being moved along a measurement route of the road surface, comprising: a means for setting a reference area for performing the calibration and a provisional reference plane on the reference area; a means for acquiring a measurement value obtained by each measuring element regarding the reference area; a means for producing point cloud data on a separation quantity of the each point from the provisional reference plane on the reference area regarding the reference area; a means for producing a reference plane for calibration based upon a statistic of the point cloud data acquired from all of the measuring elements; a means for computing a separation quantity from the reference plane for calibration of the statistic about all of the measuring elements; a means for determining a measuring element where the separation quantity is maximum of from among all of the measuring elements; a means for calibrating the measuring element so as to make a difference between point cloud data produced from a measurement value of the measuring element where the separation quantity is maximum and the reference plane for calibration less than a predetermined threshold; a means for producing a new reference plane for calibration from measurement values obtained by all the measuring elements including the calibrated measuring element; and a means for determining a final calibration value of each measuring elements by repeating computing a separation quantity from the reference plane for calibration of the statistic regarding, all of the measuring elements, determining a measuring element where the separation quality is maximum from among all of the measuring elements, calibrating the measuring element so as to make a difference between point cloud data produced from a measurement value of the measuring element where the separation quantity is maximum and the reference plane for calibration equal to or less than a predetermined threshold, and producing a new reference plane for calibration from all of the measuring elements including the calibrated measuring element until the separation quantities from the reference plane for calibration of the point cloud data obtained by all of the measuring elements become smaller than a predetermined reference value. ### Claim 9 (depends on 8) The apparatus for evaluating road surface properties provided with the apparatus for evaluating road surface properties according to claim 8, where evaluation of the road surface is performed based upon the calibration value. ### Claim 10 (depends on 2) The method for calibrating unevenness of a plurality of measuring elements in an apparatus for evaluating road surface properties according to claim 2, wherein the reference area is set at a specified place in the measurement route of the road surface to be measured. ### Claim 11 (depends on 2) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 2, wherein the reference area is set at least one of a place corresponding to a starting position of the measurement route and a place corresponding to a terminating position thereof. ### Claim 12 (depends on 3) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 3, wherein the reference area is set at least one of a place corresponding to a starting position of the measurement route and a place corresponding to a terminating position thereof. ### Claim 13 (depends on 2) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 2, wherein a flat plate is disposed on the reference area. ### Claim 14 (depends on 3) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 3, wherein a flat plate is disposed on the reference area. ### Claim 15 (depends on 4) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 4, wherein a flat plate is disposed on the reference area. ### Claim 16 (depends on 5) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 5, wherein a flat plate is disposed on the reference area. ### Claim 17 (depends on 2) The method for evaluating road surface properties including the method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 2, wherein each measuring element is calibrated based upon the calibration value to perform evaluation of the road surface. ### Claim 18 (depends on 2) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 2, wherein each measuring element is calibrated based upon the calibration value to perform evaluation of the road surface and the road surface properties thereof. ### Claim 19 (depends on 3) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 3, wherein each measuring element is calibrated based upon the calibration value to perform evaluation of the road surface and the road surface properties thereof. ### Claim 20 (depends on 4) The method for calibrating unevenness of a plurality of measuring elements in the apparatus for evaluating road surface properties according to claim 4, wherein each measuring element is calibrated based upon the calibration value to perform evaluation of the road surface and the road surface properties thereof.