WO2019231336A1 - Procédé et système de mesure de déformation d'une surface - Google Patents

Procédé et système de mesure de déformation d'une surface Download PDF

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Publication number
WO2019231336A1
WO2019231336A1 PCT/NZ2019/050058 NZ2019050058W WO2019231336A1 WO 2019231336 A1 WO2019231336 A1 WO 2019231336A1 NZ 2019050058 W NZ2019050058 W NZ 2019050058W WO 2019231336 A1 WO2019231336 A1 WO 2019231336A1
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WIPO (PCT)
Prior art keywords
gyroscope
deformation
wheel
measure
pavement
Prior art date
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PCT/NZ2019/050058
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English (en)
Inventor
Graham Alexander SALT
Original Assignee
Pavement Analytics Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pavement Analytics Limited filed Critical Pavement Analytics Limited
Priority to AU2019279457A priority Critical patent/AU2019279457A1/en
Publication of WO2019231336A1 publication Critical patent/WO2019231336A1/fr
Priority to US17/106,475 priority patent/US20210080242A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0075—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by means of external apparatus, e.g. test benches or portable test systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/28—Measuring arrangements characterised by the use of mechanical techniques for measuring roughness or irregularity of surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
    • B60C23/06—Signalling devices actuated by deformation of the tyre, e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle
    • B60C23/064—Signalling devices actuated by deformation of the tyre, e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle comprising tyre mounted deformation sensors, e.g. to determine road contact area
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0066—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by exciting or detecting vibration or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass
    • G01M99/004—Testing the effects of speed or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass
    • G01M99/007—Subject matter not provided for in other groups of this subclass by applying a load, e.g. for resistance or wear testing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C19/00—Tyre parts or constructions not otherwise provided for
    • B60C2019/004—Tyre sensors other than for detecting tyre pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/14—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of gyroscopes

Definitions

  • the present invention relates to determination of one or more structural parameters of a surface.
  • Load bearing capability is a fundamental property that requires quantification for all types of pavement structures. This encompasses roads (both local and state highways), airport runways, heavy duty pavements and in many earthfills and hardfills where adequate compaction and strength are important. Pavement structural capacity may deteriorate, over time, owing to a number of factors, including changes in the elastic moduli of sub-pavement layers of bound layers, aggregates or earth.
  • the load bearing capability of the pavement can be periodically tested to quantify its structural condition. It is desirable to utilise technologies that are non-destructive so that the integrity of the pavement surface is maintained. Further, the measurements should desirably be made rapidly or at least at customary traffic speed, through an automated system, to minimize time, avoid impediments or risk to road users and reduce costs.
  • Deflectometers measure the deflection of a surface (such as a road or pavement) under a given force and use this deflection either to calculate some strength or stiffness parameter (e.g. the elasticity modulus) or to use the deflection as a direct empirical measure of the strength and stiffness.
  • some strength or stiffness parameter e.g. the elasticity modulus
  • the Lacroix and California Traveling Deflectograph were based on the Benkleman Beam and utilise probes placed on the road surface to measure the deflection from a constantly moving lorry. These devices a re limited to a maxim um speed of about 7 km ph .
  • the French Curviametre utilises Geophones mounted on a continuous closed-loop track passing between two wheels (i.e. the wheels do not drive on the chain) with the chain travelling on the pavement surface between dual rear wheels. Measurements are taken when the chain approaches and passes between the two rear wheels.
  • the fifteen meters long closed-loop chain is equipped with three geophones generating a result every five meters. This design was limited to a top speed of about 20 kmph. With this device the track passes in the space between dual wheels, not beneath a loaded tyre, nor does this device test at highway speed.
  • TSD or Traffic Speed Deflectometer traditionally using laser velocity measurement from a horizontal beam on the test vehicle, measures pavement vertical velocity with a row of sensors extending horizontally in the direction of travel from the centre of loaded dual wheels. It is carried out while the testing equipment is intended to be travelling at traffic speed, but in practice is often limited to 70 kmph because trucks tend to set up vibrations so the signal to noise ratio deteriorates at higher speeds, usually limited to well below 100 kmph.
  • RWD or Rolling Weight Deflectometer traditionally using laser distance measurement from a horizontal beam on test vehicle, to measure pavement deflection between loaded dual wheels with a row of sensors extending horizontally in the direction of travel. It is intended to be carried out while the testing equipment is travelling at traffic speed.
  • the Purdue Deflectograph includes at least four non-contact laser range finders mounted in a line a long the vehicle. A geometric relationship is then used to calculate the deflection.
  • High Speed Deflectographs use laser Doppler velocity-meters rather than the "standard" laser tria ngulation distance-meters. These devices are, however, complex and capital cost is expensive.
  • the TSD and RWD systems utilise a fast moving, heavy dual wheel load that rolls along the pavement, with sensors being arranged at intervals out from between the centre of the dual wheels to measure deflection. A device of this type is disclosed in U.S. Pat. No. 4,571,695.
  • a load is placed on a dual wheel assembly that rolls along the pavement and the depth of a deflection basin created by the loaded dual wheels is measured using precision laser sensors mounted on a horizontal member that tracks with the dual wheel.
  • Such deflection measurements provide insight into the load bearing capability of the pavement.
  • pavement deflections are usually very small, typically 0.010 to 0.100 inch for a 20,000 pound applied axle load. Therefore, not only are extremely sensitive sensors required to measure the deflection, but the sensors should have a stable reference plane.
  • DSD Dynamic Screening Deflectometer
  • a gyroscope alone may provide useful information to determine surface deformation and can in fact provide superior results to an accelerometer alone, particularly at speeds above about 70 kmph.
  • Gyroscopes alone have never been used for pavement analysis as the expectation was that drift resulting from the required double integration and noise would overcome any useful signals.
  • a less noisy signal is actually produced by a gyroscope at speeds over about 70 kmph than from an accelerometer because of the particular nature of truck vibration on a road coupled with the way the sensor is impressed onto a surface over the cycloid stationary period, such that it is largely insensitive to the prevailing waves that are set up by a moving vehicle.
  • the gyroscope as used in the DSD has an important difference in that it is the only device that can directly measure rotational velocity at the centrepoint of the tyre load and can therefore enable a direct measure of curvature of the surface at the point of maximum curvature which enables the properties of the layer closest to the surface to evaluated.
  • Other devices focus on the point between dual wheels which has lesser curvature than under the loaded wheel, and is less sensitive to the properties of the pavement forming and immediately beneath the surface.
  • the gyroscope signal may be integrated with respect to time to determine additional parameters including in particular the curvature of the pavement deflection bowl at the point of application of the rolling load (i.e. angular displacement).
  • additional parameters including in particular the curvature of the pavement deflection bowl at the point of application of the rolling load (i.e. angular displacement).
  • the advantage now is the compact size and low cost of sensors. Gyroscopes are also available in a composite form (inertial measurement unit or IMU), most with capacity to measure magnetic orientation and acceleration.
  • IMU intial measurement unit
  • gyroscope and rotational velocity are used below, but they are used herein to denote each of the characteristics detected by one or more gyroscopes, accelerometers or IMUs (or calculated from their measurements) and including one or more relevant parameters, being acceleration, linear velocity, angular velocity, jolt and magnetic orientation, about any or all three dimensions, measured individually, with reference to either a single or multiple axes, or in any combination, in the situations and for the purpose described below.
  • the present invention relates to determination of one or more structural parameters of a surface, particularly, although not exclusively, the invention relates to non-destructive testing of pavements and in particular to methods and apparatus for determination of pavement structural parameters including e.g. one or more of deflection, curvature and stiffness of pavements as well as direct correlations with distress severity.
  • the testing can be carried out at either fast or slow speeds using one or more rolling weights or wheel(s).
  • the same concept used for measurement at high speed can also be used at slow speed.
  • inspection of the gyro signatures have revealed an additional purpose and a methodology that has now been developed.
  • the methodology for the first time overcomes the limitations in the LNEC trials in the 1990' s, that is: to use one or more gyroscopes or IMU's with one or more axes in a stationary setting placed in close contact on, or in the surface a short distance away from the loaded wheel followed by a new methodology for relating the gyro measurements to structural propertries including one or more of rate of rotation, deflection, curvature, or layer moduli.
  • This particular methodology when used in earthworks construction enables construction quality control of earthworks much more quickly and cheaply than any existing method.
  • a method of measuring deformation or structural properties of a surface comprising:
  • a system for measuring the deformation or stuctural properties of a surface including:
  • a gyroscope or gyroscopes positioned on or near the rolling weight to measure deformation at or near the periphery of the rolling weight
  • iii extracts rotational information for the identified stationary periods; and iv. develops one or more measures of surface deformation or structural properties based on the extracted gyroscope information.
  • a system for measuring the deformation or structural properties of a surface including:
  • a gyroscope positioned on or near the rolling weight to measure deformation at or near the periphery of the rolling weight; and c. a signal analysis circuit which:
  • ii. identifies stationary or stationary cycloid periods based on user input
  • the gyroscope may be positioned on or near the periphery of the rolling weight, on or near the periphery of a wheel near the rolling weight or be mounted in or to the surface.
  • a system for measuring the deformation or structural properties of a surface including:
  • a gyroscope positioned to measure deformation proximate to the surface for direct force transmission from the surface;
  • a tyre belt or mesh adapted to fit to the tyre of a vehicle for measuring the deformation of a surface
  • a belt adapted to be fitted about a vehicle tyre having one or more gyroscope sensors positioned to measure deformation at or near the periphery of the belt.
  • a tyre for measuring the deformation of a surface including one or more gyroscopes positioned to measure deformation at or near the periphery of the tyre.
  • a method of determining water content of material underlying a surface by measuring deformation of the surface at or near a rolling weight and determining water content of the underlying material based on the relative smoothness of the shape of the response curve compared with a reference curve of a surface having known water content.
  • Figures 1A to 1C illustrate a trajectory defined by a device mounted at or near the periphery of a rolling wheel
  • Figure 2 shows a rolling weight having a plurality of gyroscopes distributed about its periphery
  • Figure 2A shows a track driven arrangement in which a plurality of gyroscopes are provided along a track driven around two wheels;
  • Figure 3 shows a gyroscope mounted within a mesh secured to a wheel
  • Figure 4 shows a gyroscope embedded within the tread of a wheel
  • Figure 5 shows a schematic diagram of a system for measuring the deformation of a surface
  • Figure 6 shows a sample recording from a gyroscope embedded in a wheel
  • Figure 7 shows a high speed event
  • Figures 8A to 8C show methods for communication of data between the sensor(s) and a computer
  • Figure 9 is a flow chart illustrating one embodiment of measurement method
  • Figure 10 shows a plot of rotational velocity versus time
  • Figure 11 shows a gyroscope forward rotation axis when the rotational velocity is measured from an adjacent wheel or from a point on the surface within the deflection bowl;
  • Figure 12 shows a gyroscope lateral rotation axis when the rotational velocity is measured from an adjacent wheel or from a point on the surface within the deflection bowl;
  • Figure 13 shows an example image of a test result displayed on a smart phone
  • Figure 14 shows example bowl deflection data
  • Figure 15 illustrates the fitting of curve fitting solutions to displacement data using Excel.
  • Figure 16 shows a range of possible valid bowl profile solutions.
  • the present invention involves positioning one or more gyroscopes at or near the perimeter of a heavily loaded rolling wheel and/or nearby rolling wheels to make possible the utilisation of the stationary period in cycloid movement when the rugged sensor housing of a gyroscope becomes pressed against the road surface.
  • the sensor may measure and record the rotation velocity versus time history of motion from which pavement curvature and/or the "signature" shape of part of the record is used to determine pavement structural properties for asset management, design or construction quality assurance.
  • the sensor may alternatively be located in or on the surface within the bowl of surface deformation, or in a wheel some distance in from the perimeter of the wheel but rigidly connected in a manner that it will record the deformation of the perimeter.
  • the gyroscope may be mounted with a rigid connection to the measuring pad which is pressed against (typically mounted to) the road.
  • the gyroscope needs to be positioned within the bowl of deflection influence, which in a typical pavement situation may be about 1.5 to 2 metres from the rolling weight.
  • This information may then then utilised to determine more than rotational velocity and according to the present invention may be utilised to determine curvature of the pavement surface as well as critical strain parameters or structural parameters that can be applied to predict bearing capacity, deformation, potential for cracking, rutting progression, roughness progression, remaining life, rehabilitation requirements and associated characteristics of pavements.
  • This approach enhances the value of pavement testing while at the same time allowing for testing systems having both slow, medium or fast moving wheel loads.
  • the collected data from multiple wheels of different configurations can be used to determine pavement life, vertical compressive strain, shear strain and horizontal tensile strain and other structural properties, which can be more valuable for the prediction of remaining pavement life and design recommendations for repair and maintenance.
  • IMUs inertial measurement units
  • An IMU is an electronic device that measures and reports a body's specific acceleration/force, angular velocity rate, and sometimes the magnetic field surrounding the body, using a combination of accelerometers and gyroscopes, and sometimes also magnetometers. IMUs often contain three accelerometers and three gyroscopes and optionally three magnetometers. The accelerometers are commonly placed such that their three measuring axes are orthogonal to each other. They measure inertial acceleration, also known as G- forces. Three gyroscopes may be placed in a similar orthogonal arrangement, measuring rate of rotation in reference to an arbitrarily chosen coordinate system.
  • Three magnetometers may also be included to allow better performance for dynamic orientation calculation. Where an IMU is employed multiple characteristics of the sensors may be used to quantify desired parameters and address instrument noise and drift. As well as rotation, acceleration and velocity may be used to determine the change in deflection over the stationary period, in particular, the curvature of the deformed shape of the pavement deflection bowl at the point of greatest curvature, which in itself is a widely used empirical parameter for design of asphaltic pavements. Detecting the earth's magnetic field may be used for orientation, including identification of any localised deviation of the vehicle path from a straight line so that anomalous readings that occur simultaneously can be corrected in the quality assurance process.
  • a horizontal pressure wave due to forward motion of the wheel as the wheel approaches a surface, followed by its reversal as it goes away from it, is a deformation characteristic that the invention may utilise, either in conjunction with or independent from, readings from other sensors on the heavily loaded wheel or nearby wheels, to determine the stiffness properties of the pavement, which are then used for remaining life and rehabilitation requirements.
  • the perimeter of a rolling wheel would be subject to very large rotations and accelerations from centrifugal forces, so any small movement of the pavement itself would be indistinguishable and attempts to construct a device that would be practical, would be futile. This is not the case, as explained below with reference to Figures 1A to 1C.
  • the dashed trajectory defines the locus of the gyroscope position on the perimeter of the wheel and the cusp that meets the solid line (road surface) defines the stationary period of the sensor, when it has zero horizontal velocity, irrespective of the velocity of the centre of the wheel (assuming the pavement is rigid). Because all road surfaces and wheels are not infinitely stiff, the compression of either will extend the stationary period from instantaneous to several milliseconds or longer and this duration can be controlled with wheel materials (or tyre pressures).
  • a rolling weight in the form of a wheel 1 has four gyroscopes 2 housed in ruggedised housings positioned about (at or near) its periphery. It will be appreciated that where a gyroscope is described below that an IMU or other ancillary sensors may be substituted.
  • the gyroscope housings are embedded within the tyre tread so that the ruggedised housings are substantially flush with the surface of the tyre tread, although they could be located anywhere at or near the tyre surface as long as adequate data could be obtained for the type of wheel used, the type of surface and the information required.
  • gyroscopes 2 Whilst four gyroscopes 2 are shown any number may be provided depending upon the measurement interval required and number of nearby wheels to widen the definition of the deformation away from the loaded wheel.
  • An alternative configuration may be to have the loaded wheel(s) not instrumented, with all measurements taken only from a nearby wheel(s) which has only nominal loading but using the same principle.
  • the stationary cycloid interval also allows enhanced analysis because pavement surface texture can also be measured using the same principle, measuring the degree of sealing achieved, when a fluid is injected centrally to the footprint of a tyre, as explained below. Correction of results for the "seating effects" of texture increases the accuracy of the structural parameters determined but also allows a new method of determining estimates of texture and hence skid resistance, which are traditional parameters collected with other high-speed vehicles which measure pavement surface properties.
  • a strain gauge coupled to an inertial mass could form a gyroscope.
  • a strain gauge housing pressed against the surface or used with an inertial mass could indirectly be used to approximate the more primary measurement of curvature made by the gyroscope.
  • the focus of this application is the measurement of pavement surface curvature at traffic speed from a device located on or in proximity to the perimeter of a rolling wheel using the stationary cycloidal period for the purposes of evaluating engineering properties of the pavement (not properties of the tyre or wheel).
  • No other device derives such a direct measure of pavement curvature at traffic speed (i.e. typically 20 to 90 km/hr). They deduce curvature indirectly from sensors that take discrete readings of vertical deformation at specific points along the deflection bowl.
  • air can be continuously supplied under pressure (readily achieved using the established central tyre inflation system) to the tyre.
  • a fine tube allows a limited flow of fluid to escape from the pressurising system through an appropriately small hole to a disc shaped cavity recessed into about the middle third of the tyre tread. Just beyond the cavity the usual tyre grooves are filled to provide an annulus of smooth rubber, flush with the tread, to promote a partial seal when in contact with the pavement during the stationary cycloidal interval.
  • the escaping fluid may be instrumented with a rapid response pressure sensor thus providing a measure of the effectiveness of the seal during each stationary interval, allowing correlation with the traditional measurement of pavement surface texture and skid resistance.
  • each gyroscope reaches a stationary period in cycloid movement (as per the gyroscope numbered 2 in Figure 2).
  • data from the gyroscope 2 may be utilised to determine surface movement as will be explained below.
  • Either one, but usually two or more sets of wheels may be instrumented, including sensors on axles with single wheels and also on axles with dual wheel configuration, with readings taken usually in each wheel track but on some occasions the vehicle may be offset laterally so that readings can be taken between wheel tracks to compare parts of the road that have not been trafficked with other parts that have.
  • a belt in the form of track 6 rotates about wheels 4 and 5.
  • a number of gyroscopes 7 are provided at intervals along belt 6.
  • point data from each gyroscope 7 may be utilised to determine surface deflection when it is directly below one of the wheels.
  • Figure 3 shows a further embodiment in which one or more gyroscopes 9 may be provided on a mesh 8 fitted to a standard vehicle wheel.
  • the mesh 8 may be of the type typically fitted to wheels to provide increased grip, such as snow chains. This approach has the advantage that a relatively inexpensive device may be fitted to a standard vehicle tyre to provide very useful measures of pavement deformation.
  • Figure 4 shows a conventional tyre 10 having a gyroscope 11 embedded in the tread so that it is flush with the tyre tread.
  • FIG. 5 shows a block diagram of a system for acquiring and processing information from a gyroscope.
  • a ruggedised case may contain a gyroscope 12, processor IB, memory 14 and transmitter 15. Data from gyroscope 12 that is supplied to processor 13 may be stored in memory and/or transmitted via wireless transmitter 15.
  • transmitter 15 may be omitted and memory 14 may be a removable memory card that may be removed from the ruggedised casing after measuring and be inserted into a computer for processing. Where wireless transmitter 15 is employed memory 14 could be omitted with all data being transmitted to receiver 16 and stored by computer 17. Other communication channels such as wired or optical links may also be employed.
  • Gyroscopes may typically be sampled at a rate of about l-10kHz.
  • Employing multiple gyroscopes to measure the pavement rotation under multiple different load configurations may be used to provide test data which may be used with correlations to determine the various traditional parameters for structural design or asset management.
  • Rotation measurements may be used to correlate against well recognised pavement structural design parameters such as curvature, standard curvature index under Falling Weight Deflectometer (FWD), deflection, or other offset parameters from the FWD, Benkelman Beam, Deflectograph, Rolling Wheel Deflectometer or Traffic Speed Deflectometer and similar traditional devices for measuring pavement structural capacity and remaining life. This allows generation of the critical strain parameters that can be applied to predict bearing capacity, rutting progression and roughness progression characteristics of pavements.
  • FWD Falling Weight Deflectometer
  • the collected data can be used to determine vertical compressive strain, shear strain and horizontal tensile strain, which can be more valuable for the prediction of remaining life time and recommendations for repair and maintenance.
  • Figure 6 shows a recording from an IMU embedded in a wheel of a fully loaded vehicle on a 5 km run with signal logged at 1 m intervals at an approximately constant speed of 70 km/hr.
  • the interpretation may use data from the gyroscope alone or the accelerometer alone, as in most forms of pavement the acceleration and rotation signals form sub-parallel traces as they increase or decrease in sympathy. However increased accuracy is generally obtained by using the signals from both the gyroscope and accelerometer.
  • the following comments for acceleration apply similarly for rotational measurements.
  • the lower shaded zone (g ⁇ 3.5) indicates pavement with strong accelerations and hence limited life. This information may be used directly or as the basis for directing traditional (FWD) tests to be performed. In this case FWD tests would be done just around the low points (here the 3 to 4 kilometre chainage), or for fuller calibration some would be done at the peaks, ie around chainage 7.0-7.2 km also.
  • FWD traditional
  • a micro-logger using a microSD card in or near the sensor housing may be adopted, or Bluetooth to a laptop computer in the vehicle if real-time monitoring is required.
  • the screening survey may be used alone, where good historic correlations with FWD or similar devices are available.
  • Data may be communicated from the sensor(s) to a processor, computing device or PC of any suitable kind by any suitable communications method, including one of those shown in Figures 8A to 8C.
  • the logger carries out high frequency sampling (usually 1 to 10 kHz) of rotational velocities and forces, logging them to memory, and sending them via Bluetooth to a laptop computer.
  • high frequency sampling usually 1 to 10 kHz
  • the data is processed using software.
  • the initial signal is filtered by picking "events" (stationary cycloid period). Data are stored for each event, including for representative intervals within each event, and for each axis, the angular velocity.
  • Rotational velocity measurements are used to correlate against well recognised pavement structural design parameters such as standard central deflection under Falling Weight Deflectometer (FWD), curvature function, surface curvature index, or other offset deflections and parameters from the FWD, Benkelman Beam, Deflectograph or Traffic Speed Deflectometer and similar traditional devices for measuring pavement structural capacity and remaining life.
  • FWD Falling Weight Deflectometer
  • curvature function curvature function
  • surface curvature index or other offset deflections and parameters from the FWD
  • Benkelman Beam Deflectograph
  • Traffic Speed Deflectometer Traffic Speed Deflectometer
  • v m the median rotational velocity measured in units radians per second centred on the mid point of the cycloidal stationary period.
  • dO Benkelman Beam deflection
  • SCI curvature
  • SCI (mm) k2 v m
  • SCI is the Surface Curvature Index (d0-d300) and kl & k2 are constants for a given testing speed and loaded tyre size, (with the gyroscope placed centrally on the perimeter of a 35 kN large single tyre such as 385 65R 22.5 inflated to 700 kPa).
  • dO the Surface Curvature Index
  • kl & k2 are constants for a given testing speed and loaded tyre size, (with the gyroscope placed centrally on the perimeter of a 35 kN large single tyre such as 385 65R 22.5 inflated to 700 kPa).
  • the magnitude of SCI is much smaller than dO, hence the signal to noise ratio makes accurate determination of SCI much more difficult for all prior art equipment because, until now, that equipment measures vertical movement.
  • the gyroscope signal has been found to be much less affected by the particular form of vibration generated by
  • start and end chainages for the road interval to be tested are obtained. These may be input manually by a user, or may be obtained automatically using a GPS device. In either case the start and end chainages may be associated with GPS coordinates.
  • one or more sensors are mounted at or near the perimeter of the tyre.
  • the sensors may be mounted in any suitable rigid housing.
  • the housings may be mounted in the tyre such that the rigid housing fits flush with the tyre surface and is firmly pressed against the road surface as the tyre rotates.
  • the perimeter of the tyre is measured in its usual state of inflation.
  • the senor is connected to a logger programmed for recording the rotational velocity.
  • the sensor and logger may be arranged to record rotational velocity over a range of at least 0-100 degrees per second at 1-10 kHz sampling. Other forms of sensors may be used for refined readings.
  • a calibration run is performed.
  • the sensor and logger are actuated, such that rotational velocity data and concurrent GPS position data are captured.
  • the testing vehicle is driven at creep speed ( ⁇ 1 km/hr).
  • the captured data is assessed to check that the gyroscope does record smoothly as the sensor rotates around tyre.
  • a data capture run is performed.
  • the testing vehicle is run at typical but relatively constant speed for the road environment between the start and finish chainages.
  • the rotational velocity may be plotted versus time and/or versus distance using the GPS information. Much of the plot may be in saturation for the sensor (i.e. the acceleration may be greater than the maximum measurable acceleration for the sensor), but in the relevant periods the rotational velocity will be between 2 and 20 degrees per second.
  • stationary cycloid periods may be identified in the recorded data, smoothing vibrations or averaging over short lengths to identify the characteristic minimum rotational velocity period, in a similar fashion to that shown in Figure 10, which shows an example plot of acceleration versus time, with both rotational velocity and accelerations exhibiting minima at about the same time.
  • the minimum rotational velocity may be identified as a median lower bound for successive readings.
  • the process may be performed graphically from time to time to ensure no anomalies are present, but conventional smoothing using software for filtering or determining running means may be used for production runs.
  • rotational velocities are measured from an adjacent wheel or from a point on the surface within the deflection bowl, a typical set of forward and lateral gyro axes recorded at slow speed are shown in Figures 11 and 12.
  • Figure 15 displays the results (i.e. location and stiffness inferred from correlation with FWD, as well as other standard parameters calculated from the stiffness using any of the various pavement design manuals).
  • a number of positions on the road may be determined where extremes are evident. That is where the rotational velocities are smallest and greatest (usually those that are below the 10 percentile or above the 90 percentile of all readings for that road). These will reflect the stiffest and weakest intervals of pavement.
  • the determined extreme intervals may be tested with any conventional pavement testing device to find the characteristic DO and SCI values.
  • any conventional pavement testing device for example, a Benkelman Beam, which records the transient surface deflection as a truck with dual wheels loaded to 40 kN travels over a given point, may be used.
  • a Falling Weight Deflectometer which applies a load of about 40 kN to a 300 mm circular plate, or any other suitable device, may be used.
  • DO is the central deflection and SCI is the curvature of the pavement under a 4.2 tonne (40 kN) dual wheel (or 300 mm load plate). Typical values of DO are 0.3 mm for a heavy duty pavement, 0.9 mm for a moderately trafficked road or 1.5 mm for a lightly trafficked road. SCI, however, is much smaller; approximately 0.2 times DO. Other parameters which may be measured are the D0-D200 curvature index or the remaining life of the pavement, from standard correlations.
  • the sensor may be correlated to the DO or SCI values (or other preferred measure) for the road under consideration (checking for sensibility using data from previous projects).
  • a more refined calibration should include speed.
  • a methodology is described for processing the data from one or more gyroscope with one or more axis, to develop a profile of the stiffness of the layer or layers beneath the surface of a pavement during construction as each layer is applied or at the end of construction, with provision of software to enable immediate decisions.
  • This allows simple and cost effective road construction and maintenance treatments such that a non-specialist user, such as a roading contractor, may be able to carry out testing and obtain most of the key information for pavement construction and maintenance decisions, including a rapid field test for determining if the compacted material is too wet, too dry or at optimum water content for compaction. Only time consuming laboratory tests provide such information currently.
  • An exemplary process is:
  • a sensing device typically containing a set of 3 gyroscopes (or usually 3 IMUs each with 3 motion sensors (gyroscope, accelerometer and magnetic field) and 3 axes (giving a total of 27 traces recorded with one wheel pass).
  • the smartphone can then immediately display both the results and interpretation of the test as shown in Figure 13, together with necessary actions for quality control and maintenance.
  • the amplitude of the gyro pulse quantifies both the stiffness of the pavement and the allowable traffic loading, while the relative width of the pulse correlates to how deep a failed section of pavement will need to be excavated and replaced with higher quality materials.
  • the first is the key consideration in new pavement construction while both in combination provide the necessary parameters for maintenance (digouts or reconstruction).
  • the new device and methodology thus address and effectively preclude the commonly encountered issue that a significant proportion of digouts undergo premature failure, often within a year, usually because the necessary depth of excavation is not accurately defined.
  • the principal information for new construction is the uniformity and stiffness of the underlying material including whether compaction requirements have been met for fill and what additional thickness of confining layers are necessary to carry specific highway traffic.
  • output is whether only the surfacing requires sealing or if deeper layers require improvement or replacement and if so how deep.
  • a smartphone can be preloaded with the necessary correlations with FWD or TSD data for any particular region.
  • much more detailed design information can be accessed by searching a national database containing several million FWD structural analyses, to generate many other parameters including the inferred pavement profile of stiffness versus depth (layer moduli and subgrade stiffness, i.e. California Bearing Ratio).
  • the exemplary description below illustrates how the sample data shown in Figure 14 may be interpreted.
  • the x axis shows the distance in metres from the centre of the loaded wheel, and the y value shows the deflection in microns of the pavement due to compression of the layers beneath from the load.
  • any standard double integration is done to convert the rotations to deflections, then any of the traditional curve fitting solutions available from recognised software packages (such as Excel in the example shown in Figure 15) are used to join the individual points into a full deflection bowl.
  • the parameters for that bowl as recorded in the database are assigned to that location.
  • the user may immediately view the parameters relevant to the situation, including for instance for existing pavements: remaining life for given traffic intensity, required overlay thickness or depth of digout for repair, stiffness (moduli) change with depth; and for earthfill construction: traditional compaction parameters (moduli and relation to optimum water content) and thickness of overlying layers to provide adequate structural capacity.
  • the immediate access to this information without needing specialist equipment or lengthy laboratory testing is the principal benefit of the procedure.
  • No other device known to the Applicant uses the stationary cycloid period for measuring rotational velocity at or near the most pertinent point of maximum loading (immediately beneath a tyre contact area), and is capable of measuring rotations effectively over such a wide range of vehicle speeds.
  • the method and system is simple and convenient, allowing measurements to be performed at normal driving speeds and having much lower capital and operating costs than all other traditional devices.
  • the data obtained may also be quickly analysed and available to users within a few minutes of testing, much sooner than any other high speed device, (for which customary delivery times are many weeks). This is because a large amount of test data can be generated, that relates simply to the most widely recognised test concepts in pavement engineering (standard deflection and curvature under a 40 kN wheel load).
  • TSD highway speed devices
  • the method described allows short-period, high frequency measurement during the stationary cycloid period experienced by a rolling weight or wheel moving at traffic speed by a device located on or in proximity to the perimeter of the wheel for the purposes of evaluating one or more engineering properties of the pavement (not properties related to the tyre or wheel).
  • the engineering properties are (i) the curvature of the pavement deflection bowl using primarily a gyroscope or less direct measure such as a strain gauge to measure bending or inertial forces during the stationary cycloid period; (ii) the texture of the surface using a fluid under measured pressure or less direct measure.
  • Structural Maintenance digout and, patching. The timing and nature of the maintenance required on the network, identifying to a resolution of 2 metres or less, the extents and form of required maintenance, the year in which that will be required, and cost.
  • the system and method mechanistically determines in a methodical fashion the reason(s) that a pavement will become terminal (fail structurally), and it does this from any well populated pavement management database, by automatically finding the critical stresses and strains that have resulted in the past for each distress mode then applying these to a pavement deterioration model to generate programmes for (i) future structural maintenance and (ii) future structural rehabilitation.
  • the programmes have a far higher level of reliability and predict far further ahead (many years) than any existing techniques for assessing future budget requirements.
  • the invention may also be used in combination with other developing technologies that use either distance or velocity measurements including RWD and stereo imaging.
  • RWD distance or velocity measurements
  • the comparison enables a very simple calibration and assurance test that is widely recognised and understood throughout the industry.
  • Embodiments of the invention are described herein with reference to schematic view illustrations. As such, the actual dimensions of the elements of the present invention may vary depending on the particular arrangement of the invention as well as the manufacturing techniques employed. Embodiments of the invention should not be construed as limited to the particular shapes or sizes of the elements illustrated herein but are to include deviations. Thus, the elements illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of an element and are not intended to limit the scope of the invention. The present invention is described herein with reference to certain embodiments, but it is understood that the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Road Repair (AREA)

Abstract

La déformation d'une surface, telle qu'une surface de chaussée, est mesurée à l'aide d'un poids de roulement ou d'une roue portant un ou plusieurs gyroscopes positionnés de sorte à mesurer la déformation se produisant au niveau d'un point sur le périmètre de la roue ou à proximité de celui-ci. On fait rouler le poids sur la surface à mesurer. Les signaux développés par lesdits gyroscopes pendant une période cycloïdale stationnaire du point sur la périphérie de la roue sont analysés pour fournir une mesure de déformation de surface sur la base du ou des signaux.
PCT/NZ2019/050058 2015-12-04 2019-05-29 Procédé et système de mesure de déformation d'une surface WO2019231336A1 (fr)

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AU2019279457A AU2019279457A1 (en) 2018-05-30 2019-05-29 A method and system for measuring deformation of a surface
US17/106,475 US20210080242A1 (en) 2015-12-04 2020-11-30 Method and system for measuring deformation of a surface

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002092364A2 (fr) * 2001-05-15 2002-11-21 Wilson Kitchener C Systeme, appareil et procede de surveillance d'automobiles et de pneus d'automobiles
WO2010073272A1 (fr) * 2008-12-23 2010-07-01 Pirelli Tyre S.P.A. Procédé et système de détermination du frottement potentiel entre un pneu de véhicule et une surface de roulement
WO2017095239A1 (fr) * 2015-12-04 2017-06-08 Pavement Analytics Limited Procédé et système de mesure de déformation de surface

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WO2002092364A2 (fr) * 2001-05-15 2002-11-21 Wilson Kitchener C Systeme, appareil et procede de surveillance d'automobiles et de pneus d'automobiles
WO2010073272A1 (fr) * 2008-12-23 2010-07-01 Pirelli Tyre S.P.A. Procédé et système de détermination du frottement potentiel entre un pneu de véhicule et une surface de roulement
WO2017095239A1 (fr) * 2015-12-04 2017-06-08 Pavement Analytics Limited Procédé et système de mesure de déformation de surface

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SAVARESI, S. M. ET AL.: "New Regressors for the Direct Identification of Tire Deformation in Road Vehicles Via ''In-Tire'' Accelerometers", IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, vol. 16, no. 4, July 2008 (2008-07-01), pages 769 - 780, XP011225842, Retrieved from the Internet <URL:http://ieeexplore.ieee.org/abstract/document/4476153> [retrieved on 20190808], DOI: 10.1109/TCST.2007.912245 *

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