1、Designation: E950/E950M 09Standard Test Method forMeasuring the Longitudinal Profile of Traveled Surfaceswith an Accelerometer Established Inertial ProfilingReference1This standard is issued under the fixed designation E950/E950M; the number immediately following the designation indicates the yearof
2、 original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement and recordingof th
3、e profile of vehicular-traveled surfaces with an acceler-ometer established inertial reference on a profile-measuringvehicle.1.2 The test method uses measurement of the distancebetween an inertial plane of reference and the traveled surfacealong with the acceleration of the inertial platform to dete
4、ctchanges in elevation of the surface along the length beingtraversed by the instrumented vehicle. In order to meet aparticular class, the transducers shall meet accuracy require-ments and the calculated profile shall meet the specifications ofthat class.1.3 The values measured represent a filtered
5、profile mea-sured from a moving plane of reference using the equipmentand procedures stated herein. The profile measurements ob-tained should agree with actual elevation measurements thatare subjected to the same filtering. Selection of proper filteringallows the user to obtain suitable wavelength i
6、nformation forthe intended data processing.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two
7、 systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bilit
8、y of regulatory limitations prior to use. Specific precau-tionary information is given in Section 7.2. Referenced Documents2.1 ASTM Standards:2E178 Practice for Dealing With Outlying ObservationsE867 Terminology Relating to Vehicle-Pavement SystemsE1364 Test Method for Measuring Road Roughness bySta
9、tic Level MethodF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentation3. Terminology3.1 Definitions:3.1.1 aliasing, vin the context of this practice, spectrumof a digitized data record exists over the range of frequenciesfrom zero to o
10、ne half the sampling frequency. If the spectrumof the original signal extends beyond one half the samplingfrequency, then those components of the signal at frequencieshigher than one half the sampling frequency will, whendigitized, be folded back into the spectrum of the digitizedsignal. The excessi
11、vely high-frequency components will thusbe “aliased” into low-frequency components.3.1.2 anti-aliasing filter, nlow-pass analog filter appliedto the original analog profile signal to suppress those compo-nents of the signal at frequencies higher than one half theintended digital sampling frequency.3
12、.1.3 frequency domain filtering, vfiltering operation per-formed by first calculating the the spectrum of the profilerecord and then multiplying the spectral components by thefrequency response transfer function of the filter.3.1.4 profile record, ndata record of the surface elevation,slope, or acce
13、leration, of arbitrary length.3.1.5 profile segment, nthat part of a profile record forwhich the profile index will be calculated.1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.31 onMethods for Measu
14、ring Profile and Roughness.Current edition approved Nov. 1, 2009. Published December 2009. Originallyapproved in 1983. Last previous edition approved in 2004 as E950 98 (2004).DOI: 10.1520/E0950_E0950M-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
15、ervice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 spatial domain filtering, va filter
16、ing operation per-formed directly on the profile record.4. Summary of Test Method4.1 The test apparatus consists of a vehicle equipped withthe necessary transducers, computing, and recording equip-ment to measure and record elevation profile of the traveledsurface (1).34.2 The sampling rate is selec
17、ted and depends on theanticipated roadway conditions and data requirements for theintended data processing.4.3 The test apparatus is driven in the wheel tracks or in thecorrect lateral location over the section of traveled surface to beprofiled. Transducers measure vertical acceleration of thevehicl
18、e and the vertical distance between the accelerometer andthe traveled surface and the longitudinal distance. Thesetransducer signals are combined by a computer to produce thelongitudinal profile of the traveled surface.5. Significance and Use5.1 The measurement of vehicular traveled surfaces usingan
19、 instrumented vehicle with an inertial plane of referenceprovides a satisfactory method for acquiring traveled surfaceprofile data (1).5.2 The profile data can be processed to produce, bysimulation, the outputs of other devices. This can be done online in real time or can be computed as a post proce
20、ss. Some ofthe devices that can be simulated include road meters (2),various straightedge devices (3), profilographs, (4), as well aspavers and grinders. Comparisons of various equipment andtheir profile computer programs are given in reference (5, 6).5.3 The raw data or the profile data can also be
21、 recorded fordata processing at a later time and for analysis by morecomplex data processing procedures.6. Apparatus6.1 The test apparatus consists of a vehicle equipped withtransducers and profile computing and recording equipment.The transducers are used to measure vertical acceleration,displaceme
22、nt, and the distance traveled. The computer is usedto process the transducer outputs to produce the computedprofile of the traveled surface. The test apparatus shall havetransducer capability for one or more tracks and a mass storagedevice for long-term storage of the data. If two wheel tracks areme
23、asured, the displacement transducers shall be mounted 1.5to 1.8 m 58 to 71 in. apart so that they measure in the twowheel tracks of the traveled surface.Aset of gauge blocks shallbe included to calibrate and validate static transducer opera-tion. Other supporting apparatus can include a driver speed
24、display and a graphical display of the profile or data. Someform of data display is recommended to ensure correct data isbeing collected.6.2 Vehicle RequirementsThe vehicle is the platform forthe mounting of the profile-measuring equipment. The vehicleshall be large enough to accommodate all the req
25、uired equip-ment without major structural modifications. The engine,steering mechanisms, and suspension components shall beadequate to allow smooth maintenance of speed and directionof travel. The environment of the interior of the vehicle shall bemaintained within tolerable limits of the instrument
26、ation andoperators.6.3 Transducers:6.3.1 AccelerometerThe accelerometer measures the ac-celeration used to establish the inertial reference. A high-quality accelerometer shall be used that meets the classrequirements of the profiling device. The accelerometer shallbe mounted on the measuring vehicle
27、 with the accelerometerssensitive axis perpendicular to the traveled surface. The accel-erometer range shall be large enough to accommodate thelevels of acceleration expected from the bounce motions of themeasuring vehicle (typically 61 g). The accelerometer shall bebiased to account for the 1-g acc
28、eleration of gravity. Theaccelerometer or external circuitry shall contain a self-calibration external voltage source that, on command, causesthe output of the acceleration signal level to change a prede-termined value. The accelerometer shall have a minimumresolution to allow profile calculation an
29、d accuracy and bias tomeet the class requirements as given in this test method.6.3.2 Displacement MeasurementA displacement trans-ducer measures the distance between the accelerometer and thetraveled surface. The transducer shall be mounted on thevehicle with its measuring axis perpendicular to the
30、traveledsurface and in line with the sensitive axis of the accelerometer.The displacement transducer shall measure the vertical dis-tance to the traveled surface continuously or sample at intervalsnot greater than that needed to allow calculated profile as givenin Table 1. The vertical resolution is
31、 that necessary to meet theclass given in Table 2.6.3.3 Distance MeasurementThe distance transducer maybe of the type that produces a series of pulses, the intervals ofwhich represent a distance along the traveled surface to aresolution needed to satisfy Table 1. The pulses are used tomeasure speed
32、and can be used to convert from a function oftime to a function of distance traveled.Any distance transducerthat produces analog or digital signals with sufficient accuracymay be used. The accuracy of the distance measurement isestablished by calibration (see 9.2.3).6.3.4 Location MarkersUse of a se
33、ction start, intermedi-ate feature location(s), and section end shall be identified bylocation marks that can be accurately detected by an automaticmeans, such as magnetic detection, photocells detection ofreflective tape, or similar means.6.4 Profile ComputationA computer shall be used toprocess ac
34、celeration and distance transducer outputs to producemeasured traveled surface profile. There are two basic methodsof computing measured traveled surface profile:6.4.1 Spatial BasedIn the spatial-based method, the trans-ducer outputs are acquired and profile data points are computed3The boldface num
35、bers in parentheses refer to the list of references at the end ofthis standard.TABLE 1 Longitudinal SamplingClass 1 less than or equal to 25 mm 1 in.Class 2 greater than 25 mm 1 in. to 150 mm 6 in.Class 3 greater than 150 mm 6 in. to 300 mm 12 in.Class 4 greater than 300 mm 12 in.E950/E950M 092as a
36、function of the distance traveled. In the spatial-basedmethod, the computation of measured road profile is indepen-dent of the vehicle measuring speed.6.4.2 Time-BasedIn the time-based system, the transduceroutputs are acquired and profile data points are computed as afunction of a fixed-time interv
37、al. In the time-based method, thecomputation of measured road profile is not independent of thevehicle measuring speed.6.4.3 Filtering that permits the computation of measuredelevation profile with no attenuation or amplification of roadprofile wave lengths at least 60 m 200 ft long at test speedsof
38、 25 to 95 km/h 15 to 60 mph shall be provided. Thecomputer and system shall not add noise in excess of 10 % ofthe displacement measuring transducer resolutions given inTable 2.6.4.4 As part of the profile computation equipment, acomputer terminal shall be provided that will allow theoperator to perf
39、orm system calibration, select system param-eters, and monitor system outputs.6.5 Driver Speed Display:6.5.1 The vehicle speed shall be displayed conveniently forthe driver to assist in maintaining the desired measuring speedon systems requiring constant speed during measurement.Some systems, especi
40、ally in the case of spatial-based systems,are independent of speed and the speedometer is sufficient.6.5.2 The displayed vehicle speed, when required, may becomputed by the profile computer from the distance pulses.Other means of measuring vehicle speed are acceptable.6.6 DisplayA display should be
41、used that allows visualmonitoring of the systems outputs. The display should allowprofile amplitudes to be displayed as a function of time ordistance traveled. Amplitude and distance scaling shall becontrolled by the operator through the profile computer termi-nal.6.7 Storage DeviceA device shall be
42、 provided for therecording and long-term storage of data or computed profile, orboth. The device shall have play back ability for additionalon-board processing or for later processing. Profile data forrecording shall be scaled by the computer to maintain storageresolution of the computed profile and
43、 to accommodate the fullrange of amplitudes encountered during normal profile mea-suring operation. Signal-to-noise (S/N) ratio shall be 10 orbetter.6.8 Event MarkerThe operator shall be provided themeans to event mark location data as part of the data records.The system may use a transducer (option
44、ally) to sense andrecord automatically location markers that have been placed onthe traveled surface.7. Safety Precautions7.1 The test vehicle, as well as all attachments to it, shallcomply with all applicable state and federal laws. Necessaryprecautions imposed by laws and regulations, as well asve
45、hicle manufacturers, shall be taken to ensure safety ofoperating personnel and other traffic.8. Digital Profile Recording8.1 The computed profile shall be recorded at adequateintervals for accurate representation of the traveled surface forthe intended use of the data. Also, antialiasing filters are
46、required when the folding frequency (one half of samplingfrequency) is close to the upper frequency of interest (seeTerminology E867). Identical antialiasing filtering shall beapplied to both the accelerometer signal and to the displace-ment measurement signal before computing profiles. The upperfil
47、ter frequency depends upon the intended use of the profile.8.2 Where two or more paths of traveled surface aremeasured, the recorded profile data for the paths shall be at thesame longitudinal location. This requirement is not necessary ifthe analysis to be used is independent of the wheel tracks (f
48、orexample, only quarter car analysis used).9. Calibration Procedures9.1 Because of the level of performance required of theclass of traveled surface profile measuring apparatus, it isimportant that the system and its components be calibratedperiodically as recommended by the manufacturer.NOTE 1Becau
49、se of the complexity of the calibration, it is recom-mended that the calibration procedure be automated to reduce or eliminateoperator involvement and decision making.9.2 Transducers:9.2.1 Acceleration TransducerThe acceleration trans-ducer shall have an internal or external calibration feature. Ameasure of the accelerometer error shall then be displayed forthe operators acceptance. As an alternative, the accelerationtransducer may be calibrated separately in the laboratory. Ineither case, an error larger than that allowed for the class shallno
