# Patent

## Title
Smoothness indicator

## Abstract

A smoothness indicator for measuring a profile of a road surface includes two or more non-contact elevation distance sensors, such as ultrasonic sensors, laser sensors, or the like. The non-contact elevation distance sensors are arranged in pairs including a trailing non-contact elevation distance sensor and a leading non-contact elevation distance sensor disposed at a known distance from the trailing non-contact elevation distance sensor along the profile. A slope sensor for measuring an angle of incidence of the leading and trailing non-contact elevation distance sensors relative to a horizontal plane is also included. The smoothness indicator generates an elevation profile of the road surface by calculating an elevation for the second location using an elevation assigned to the first location and an elevation difference between the first location and the second location.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of U.S. patent application Ser. No. 11/451,615, filed Jun. 12, 2006, entitled “SMOOTHNESS INDICATOR,” now abandoned, which in turn is a divisional of U.S. patent application Ser. No. 10/876,258, filed Jun. 23, 2004, entitled “SMOOTHNESS INDICATOR,” now abandoned, which in turn is a continuation-in-part of U.S. patent application Ser. No. 10/098,981, filed Mar. 15, 2002, now U.S. Pat. No. 7,044,680, entitled “Method and Apparatus for Calculating and Using the Profile of a Surface,” issued May 16, 2006. U.S. patent application Ser. Nos. 11/451,615, 10/876,258 and 10/098,981 are herein incorporated by reference in their entirety.


FIELD OF THE INVENTION
The present invention generally relates to the field of road surface profiling, and more particularly, to a smoothness indicator for measuring a profile of a road surface.
BACKGROUND OF THE INVENTION
Methods for finishing paved surfaces such as concrete presently use a paving machine to slip form edges, screed and trowel the surface, and insert structural steel. Because contractors are frequently graded on the smoothness of the finished surface, it is desirable to profile the surface for determining whether modifications such as grinding are required. Typically, pavement of a road is completed and the road surface is allowed to set up or cure to a point of hardness such that surface profile measurements may be taken for determining whether the surface meets smoothness requirements. The surface profile measurements are used to calculate index values for the road surface, such as Profile Index (PI) values and International Roughness Index (IRI) values.
After the paved surface has set up, a surface profile is taken with a profilograph, such as a California profilograph, which is wheeled along the road for creating a roughness profile of the road. Then, modifications to the road surface such as grinding may be conducted to meet specifications. This is a costly technique for altering the road surface.
Thus, it would be desirable to provide a method for measuring a surface profile while the road surface is in a plastic state, for immediate modification of the surface as well as correction of paving machine settings. Preferably, an independent vehicle or rig is utilized for increased versatility.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a smoothness indicator for measuring a profile of a road surface. The smoothness indicator may be used for measuring a profile of a paved surface, such as a surface paved with concrete or asphalt; a base course including base courses of cement treated base (CTB), lean concrete base, crushed stone, and crushed slag; a subbase, such as a subbase of subgrade soil or aggregate; a subgrade upon which a subbase, a base, a base course, or pavement is constructed; other graded surfaces including sand, rock, and gravel; or surfaces which have not been graded. The smoothness indicator may be used to measure profiles for surfaces which have not cured, such as freshly paved concrete still in a plastic state.
The smoothness indicator includes a bridge rig assembly for spanning the road surface without contacting the road surface. The bridge rig includes a drive system for moving the bridge rig along the road surface. The bridge rig supports one or more sensor assemblies over the road surface. Each sensor assembly includes a pair of non-contact elevation distance sensors, disposed at a known distance from one another for measuring distances to the road surface, and a slope sensor for measuring angles of incidence of the sensors relative to a horizontal plane. An elevation profile is generated by periodically calculating elevations along the road surface using the measured distances and the angles of incidence.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:
FIG. 1 is an isometric view illustrating a smoothness indicator in accordance with an exemplary embodiment of the present invention;
FIG. 2 is an isometric view of the smoothness indicator illustrated in FIG. 1;
FIG. 3 is a side elevation view of the smoothness indicator illustrated in FIG. 1, wherein a side of the smoothness indicator is illustrated on a paved surface;
FIG. 4 is another side elevation view of the smoothness indicator illustrated in FIG. 1, wherein the smoothness indicator is illustrated straddling a paved surface;
FIG. 5 is an isometric view illustrating a smoothness indicator in accordance with another exemplary embodiment of the present invention, wherein the smoothness indicator is capable of extension and retraction;
FIG. 6 is an isometric view illustrating a smoothness indicator in accordance with a further exemplary embodiment of the present invention;
FIG. 7 is an end elevation view of the smoothness indicator illustrated in FIG. 6;
FIG. 8 is an isometric view illustrating a slip form paver including a smoothness indicator in accordance with another exemplary embodiment of the present invention;
FIG. 9 is a partial isometric view of the slip form paver illustrated in FIG. 8;
FIG. 10 is a partial cross-sectional isometric view of the smoothness indicator illustrated in FIG. 8, further illustrating an ultrasonic sensor assembly;
FIG. 11 is a partial cross-sectional end elevation view of the smoothness indicator illustrated in FIG. 8, wherein an ultrasonic sensor assembly includes a temperature gauge assembly;
FIG. 12 is a side elevation view illustrating a sensor assembly for use with a smoothness indicator in accordance with an exemplary embodiment of the present invention;
FIG. 13 is a side elevation view of the sensor assembly illustrated in FIG. 12, wherein the sensor assembly is shown in operation at an angle θ;
FIG. 14 is a side elevation view of the sensor assembly illustrated in FIG. 12, wherein the sensor assembly is shown in operation at a first position P1 and a second position P2;
FIG. 15 is a side elevation view illustrating a profile of a road surface in accordance with an exemplary embodiment of the present invention, wherein the road surface is marked off in a series of horizontal increments, and an average elevation between the increments, δ, is shown;
FIG. 16 is an end elevation view illustrating a smoothness indicator in accordance with a further exemplary embodiment of the present invention, wherein the smoothness indicator includes a series of sensor assemblies positioned over tire track locations on a road surface;
FIG. 17 is a side elevation view illustrating translation of a sensor assembly for use with a smoothness indicator in accordance with an exemplary embodiment of the present invention;
FIG. 18 is a side elevation view illustrating rotation of a sensor assembly for use with a smoothness indicator in accordance with a further exemplary embodiment of the present invention;
FIG. 19 is a flow diagram illustrating a method for profiling a surface in accordance with an exemplary embodiment of the present invention;
FIG. 20 is a system diagram illustrating a smoothness indicator in accordance with another exemplary embodiment of the present invention;
FIG. 21 illustrates a setup screen for a smoothness indicator graphical user interface in accordance with an exemplary embodiment of the present invention;
FIG. 22 illustrates a job information screen for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 23 illustrates two real time traces of a measured surface profile for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 24 illustrates a single trace of the measured surface profile for the smoothness indicator graphical user interface shown in FIG. 21, wherein a user of the smoothness indicator may view the single trace at a specified location;
FIG. 25 illustrates two traces of the measured surface profile for the smoothness indicator graphical user interface shown in FIG. 21, wherein the user may view the traces at a specified location;
FIG. 26 illustrates a measurement options screen for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 27 illustrates a bump alarm options screen for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 28 illustrates a Profile Index report screen for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 29 illustrates an International Roughness Index report screen for the smoothness indicator graphical user interface shown in FIG. 21;
FIG. 30 is an isometric view illustrating a smoothness indicator including a bridge rig having a cantilevered arm in accordance with an exemplary embodiment of the present invention; and
FIG. 31 is an isometric view illustrating a smoothness indicator including an all terrain vehicle (ATV) having a cantilevered arm in accordance with an exemplary embodiment of the present invention.



DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.
Referring generally to FIGS. 1 through 31, a smoothness indicator 10 for measuring a profile of a surface in accordance with exemplary embodiments of the present invention is described. The smoothness indicator 10 may be used for measuring a profile of a paved surface such as concrete; a base course including cement treated base (CTB), lean concrete base, crushed stone, and crushed slag; a subbase, such as subgrade soil or aggregate; a subgrade upon which a subbase, a base, a base course, or pavement is constructed; and other graded surfaces including sand, rock, and gravel. The smoothness indicator 10 may also be used for measuring a profile of a surface which has not been graded.
The smoothness indicator 10 includes one or more sensor assemblies each having two elevation distance sensors. In exemplary embodiments of the present invention, the elevation distance sensors comprise non-contact sensors, such as ultrasonic sensors, laser sensors, or the like. In this manner, the smoothness indicator 10 may be used to measure profiles for surfaces which have not cured, such as freshly paved concrete in a plastic state. Each non-contact elevation distance sensor has a footprint over which a distance measurement is taken. In this manner, measurements taken by a non-contact elevation distance sensor reflect a portion of the surface included within the bounds of the sensor's footprint. This may have a smoothing/averaging effect for providing a more characteristic representation of the surface. Preferably, the footprint of a non-contact elevation distance sensor is of sufficient diameter for smoothing the effect of measurement of minor imperfections in the paved road surface, such as texture on the surface (e.g. skid surface texture), cracks, seams, pebbles, glass shards, and the like, which may be disposed upon the road surface. Further, in exemplary embodiments, the footprint of a non-contact elevation distance sensor approximates the footprint of a typical automobile tire (i.e. the surface space occupied by the tire), for providing a surface profile characteristic of travel of the automobile tire upon the surface. In the exemplary embodiment illustrated, for example, each non-contact elevation distance sensor has a circular footprint with approximately a 6-inch diameter. However, it will be appreciated that sensors may provide footprints of greater or smaller diameters without departing from the scope of the present invention. Those of skill in the art will appreciate that various surfaces may be profiled by the smoothness indicator 10 of the present invention. Additionally, while two elevation distance sensors are shown in the accompanying figures, those of skill in the art will appreciate that more than two elevation distance sensors may also be utilized without departing from the scope of the present invention.
Preferably an independent vehicle or rig is utilized for increased versatility. For instance, when a road is paved in concrete using a slip form paving machine or the like, a contractor may be graded on meeting smoothness requirements for the road surface. Utilizing an independent rig including the smoothness indicator of the present invention, the smoothness of the road may be determined as the road is paved. For example, the rig may be driven along behind the paver, while the smoothness indicator generates a surface profile of the freshly paved road. When a surface irregularity, such as a must-grind bump or a low spot, is encountered, personnel are alerted and work to correct the irregularity, such as utilizing a bull float, a troweling machine, a roller, or the like, while the concrete is still in a plastic state. Then, the rig may be driven over the area of the irregularity to verify that the corrected road surface meets smoothness requirements. Additionally, the smoothness indicator may be used to gauge the effectiveness of paving machine settings. In a further example, a paver is connected to the smoothness indicator via a wireless connection for providing smoothness data to the paving machine supervisor/operator or for automatic updates.
Referring to FIGS. 1 through 7, a smoothness indicator 10 in accordance with an exemplary embodiment is described. Preferably, the smoothness indicator 10 includes an extensible and retractable bridge rig assembly 12 having one or more sensor assemblies 100. For example, the bridge rig 12 may be extended over a four-lane road and retracted for a two-lane road. The sensor assemblies 100 are positioned for measuring locations upon a road surface 150, such as where automobile tires travel upon the road. In a first embodiment, the sensor assemblies 100 may be manually positioned, and a setscrew may be provided for locking a sensor assembly 100 in place. Alternatively, a drive assembly may be utilized for automatically adjusting the sensor assembly 100 to a pre-selected position.
In the present example, the bridge rig 12 includes a height adjustment assembly 14, such as an assembly including a hydraulic piston, a mechanical linkage, or the like, for adjusting the height of the bridge rig and positioning a sensor assembly 100 a distance from the road surface 150. This may be desirable for maintaining the sensor assembly in an optimal range while profiling the surface. For example, an operator may wish to maintain a sensor assembly 100 a distance between 18 and 24 inches from the road surface 150. It is contemplated that the operator may position the bridge rig 12 at a median height (the median height being relative to the distance between a sensor assembly and the road surface), such as to account for a banked turn. In further embodiments, the smoothness indicator 10 transmits a command to the height adjustment assembly 14 to position a sensor assembly 100 at a specified distance from the road surface 150. For instance, the operator may specify a distance at which the sensor assembly should be located from the road surface. The smoothness indicator may then transmit a command to the height adjustment assembly. Those of skill in the art will appreciate that the command to the height adjustment assembly 14 may be transmitted electronically, mechanically, or the like without departing from the scope of the present invention.
The bridge rig assembly 12 includes at least one travel distance sensor 710 connected to a wheel 16 of the bridge rig. The travel distance sensor 710 measures distances traveled by the wheel of the rig to determine distances traveled by a sensor assembly 100. In embodiments, two or more travel distance sensors are included for determining distances over non-linear terrain, such as distances around a sweeping highway curve. For instance, in the embodiment illustrated, two encoders and two pulse pickups may be utilized to measure longitudinal distances traveled by two wheels of the bridge rig assembly 12 (one encoder and one pulse pickup for each wheel). For example, if first and second travel distance sensors 710 are included with wheels 16 on both sides of the bridge rig 12, a weighted average of distance measurements from the travel distance sensors may be utilized to calculate a distance traveled by a sensor assembly between them. For instance, an average distance may be used for a sensor assembly 100 located in the center of the bridge rig 12. Alternatively, a distance traveled by a sensor assembly one-fourth a distance from the first travel distance sensor to the second travel distance sensor may be calculated by taking 25 percent of a distance measured by the first travel distance sensor and adding 75 percent of a distance measured by the second travel distance sensor. In a further example, a distance measuring wheel may be included with the smoothness indicator 10 for determining distances traveled by a sensor assembly 100.
In further embodiments, the smoothness indicator 10 includes one or more contact sensors 18. A contact 20 is included for measuring a distance between the bridge rig 12 and a guide, such as a string line positioned for guiding a paver, or the like. For example, a contact sensor 18 may follow a string line 22 for automatically directing the bridge rig 12 when measuring a surface profile. The contact 20 follows the string line as the bridge rig advances over the road surface 150. By analyzing movement of the contact 20, the smoothness indicator positions the bridge rig 12 for travel in a direction following the direction of the road. In another embodiment, an elevation distance sensor assembly is utilized to guide the bridge rig by tracking a line, which may be rope or another type of line detectable by the elevation distance sensor.
A feedback and actuator assembly may be utilized to control the wheel 16 of the bridge rig 12. The feedback and actuator assembly may include a feedback sensor (such as a rotary potentiometer, or the like, for sensing an angle of the wheel 16), an actuator, and/or a control assembly, for guiding the angle of the wheel 16, controlling its rotational velocity, and/or directing another characteristic of the wheel's movement. For example, a computer assembly or an integrated circuit utilizing control logic senses a characteristic of the wheel's movement via the feedback sensor and guides the wheel 16 via the actuator. The feedback and actuator assembly may be coupled with the contact sensor 18 (or the elevation distance sensor) for controlling the direction of travel of the bridge rig 12. Alternatively, the bridge rig and/or the wheel are controlled by a Global Positioning System (GPS) directing the rig. In this manner, the bridge rig 12 may travel a predetermined course.
In a further embodiment, the smoothness indicator 10 may be utilized to compare elevation measurements for a subgrade against elevation measurements for a string line. For example, a string line may be utilized by a paver for determining the thickness of a paved surface, such as the road surface 150, to be constructed upon a subgrade. Thus, a percentage yield for a paving material such as concrete may be determined by comparing elevation measurements for the subgrade against elevation measurements for the string line. Additionally, pavement thicknesses may be determined at various locations, and surface inconsistencies, which can reduce the percentage yield of a paving material, may be identified. In one embodiment, an elevation profile measured by a sensor assembly 100 for the subgrade is compared against an elevation profile measured for the string line (e.g. elevation measurements of the string line made by an elevation distance sensor). Alternatively, a profile of elevation difference measurements is generated, such as by measuring elevation differences between a subgrade and a string line at various locations. In a still further embodiment, elevation measurements for either of the subgrade and the string line are compared against theoretical elevation measurements for the other of the subgrade and the string line.
Typically, dimensions such as length, width, and depth of a concrete slab to be constructed upon a subgrade are specified. These dimensions may be used to calculate a design volume (i.e., the theoretical volume of paving material needed to construct the slab) which may be compared to an expected volume calculated from the elevation measurements for the subgrade and/or the string line to determine a predicted volume difference or overall average volume change (if elevation profiles from multiple sensor assemblies 100 are used). If the predicted volume differences or overall average volume change are to be excessive, the subgrade may be modified accordingly in order to reduce or eliminate the actual volume difference after paving, saving paving material and reducing the cost of the slab. Those of skill in the art will appreciate that other data may be calculated by comparing subgrade and/or string line elevation measurements without departing from the scope and intent of the present invention.
The smoothness indicator 10 is capable of profiling a surface in either a forward or a reverse direction. For example, the bridge rig 12 may travel in a forward direction behind a paver. Upon detection of a surface irregularity, such as a must-grind bump or a low spot, the smoothness indicator 10 may emit an audible alarm, a visual alarm, or the like, to notify personnel to correct the irregularity. An operator may then drive the bridge rig assembly 12 backward and forward over the area of the surface irregularity, repeatedly (if necessary) measuring the surface until proper correction and/or minimization of the irregularity has been achieved. Various options may be provided for identifying surface irregularities, such as parameters for must-grind bump size, and other surface criteria.
In one embodiment, previous elevation measurements for locations measured along the road surface 150 are replaced with more recent elevation measurements for the same locations. For example, elevations measured for locations along the road surface before the bridge rig 12 is driven backwards over an area are replaced by elevations measured when the bridge rig assembly is driven forward over the area. This has the advantage of reflecting the corrected profile of the road surface 150 when measuring is resumed.
The smoothness indicator 10 may be utilized for profiling a variety of surfaces. Different intervals may be used for averaging measured elevations when profiling the surfaces, minimizing the elevations associated with a profile. For instance, a two-inch interval may be utilized when measuring a concrete surface, while a one-fourth inch interval may be utilized for a subgrade. The smaller interval may allow for the detection of rocks, glass, and the like. In still a further embodiment, an averaging ski may be used with the sensor assembly 100 for measuring a subgrade. In this instance, two averaging skis may be used with the sensor assembly 100: a leading averaging ski, and a trailing averaging ski. It should be noted that various contacting and non-contacting sensors may be used with the smoothness indicator 10 of the present invention to optimize detection for a particular surface without departing from the scope thereof.
In embodiments, the bridge rig assembly 12 includes a seat 24 for supporting an operator. The seat may be adjustable for allowing the operator a less obstructed view of the road surface 150 or for purposes of comfort. Additionally, the bridge rig 12 includes a steering wheel 26 for manually controlling the position of the bridge rig, such as when driving the rig to a job-site. (Preferably, the bridge rig is oriented longitudinally with a road when driving to a job-site, occupying one lane of the road.) The steering wheel 26 may be used to override directional commands, while a lockout feature may be provided for preventing inadvertent direction changes. Preferably, a graphical user interface assembly 28 is included for setting parameters, entering information, viewing data, and controlling the smoothness indicator 10. A printer 30 may be provided for generating a hard copy, such as a surface profile measured by the smoothness indicator 10, or related data.
In order to generate a surface profile, the smoothness indicator 10 utilizes a trailing (first) non-contact elevation distance sensor 110 and a leading (second) non-contact elevation distance sensor 115 to measure a distance D1 and a distance D2 from a road surface 150. By measuring angles of incidence of the sensors 110 and 115, and utilizing a known/pre-selected distance D3 between the sensors, an elevation for a first location L1 may be calculated using an elevation assigned to a second location L2. It will be appreciated that the terms trailing/first and leading/second are used to describe non-contacts sensors 110 and 115 in relation to the direction of travel of the smoothness indicator 10. In exemplary embodiments, the bridge rig 12 may travel in two directions. Thus, a trailing/first non-contact elevation distance sensor may become a leading/second non-contact elevation distance sensor if the direction of travel is reversed. Alternatively, a leading/second non-contact elevation distance sensor may become a trailing/first non-contact elevation distance sensor in the same manner. For the following description, let the x axis be oriented in a direction parallel to motor vehicle travel on the road surface.
For the present invention, an elevation profile of the road surface is constructed using a method called the “Incremental Slope Method” (ISM). ISM constructs a road-surface elevation profile by measuring the slope between successive pairs of points, such as locations (x1, y1) and (x2, y2), (oriented such that a line drawn between these points and the x axis define a plane) on the road surface, which are separated by a known distance. Using an elevation/benchmark assigned to one point, it is possible to calculate an elevation for the other point as

y1=y0+mdx 

where y0 and y1 are the elevations of the points at x0 and x1, respectively; m is the slope between points 0 and 1; and dx is the known horizontal distance between the two points.
By moving the sensors in the x-direction a known distance less than dx, the process can be repeated and a surface elevation profile constructed in desired increments. Thus, a priori knowledge or an estimate of the profile for the road surface in the region, x0≦x≦x0+dx is needed. Then, for x0+dx<x, elevations may be calculated, and the road-surface profile constructed as desired (within tolerances of the sensors and other equipment).
For the following analysis, the following definitions are used (see FIG. 13):

    
    
        x is the coordinate on the abscissa, lying in a horizontal orientation longitudinally along a road. This coordinate will curve with the road, but always lies in a horizontal plane.
        y is the coordinate used on the ordinate, oriented in the vertical direction.
    
    


Referring now to FIGS. 8 through 18, in a further embodiment, the smoothness indicator 10 includes a first ultrasonic sensor 110 and a second ultrasonic sensor 115, separated by a pre-selected distance d 130. The first and second ultrasonic sensors 110 and 115 use active ultrasonic ranging for measuring the distance to the surface, e.g. from a sensor to the road surface 150. By comparing distance measurements obtained by the first and second ultrasonic sensors 110 and 115, an elevation difference between locations on the road surface 150 is computed. For instance, by measuring a first distance h1 from the first ultrasonic sensor 110 to a first location (x1, y1) on the road surface 150 and a second distance h2 from the second ultrasonic sensor 115 to a second location (x2, y2) on the road surface 150, an elevation difference h3 between the first and second locations is computed.
Those of skill in the art will appreciate that the smoothness indicator 10 may not travel a level course, due to uneven terrain, thus causing the first and second ultrasonic sensors 110 and 115 to assume various angles of incidence relative to a horizontal plane. Electronic circuitry, mathematical formulae, or other techniques may be used to calculate the elevation difference h3 between the first location (x1, y1) and the second location (x2, y2), such as by noting the various angles of the first and second ultrasonic sensors relative to the horizontal.
The first and second ultrasonic sensors 110 and 115 are oriented along a line having a slope θ from the horizontal. In embodiments, the ultrasonic sensors are positioned such that the sensors face the road surface substantially perpendicular to the line having slope θ from the horizontal. This places the first and second ultrasonic sensors 110 and 115 at the same angle of incidence relative to the horizontal, namely slope θ. The elevation difference h3 between the first location (x1, y1) measured by the first ultrasonic sensor 110 and the second location (x2, y2) measured by the second ultrasonic sensor 115 relative to the road surface 150 is computed using the pre-selected distance d 130, the first and second distances (h1 and h2), and the slope θ. The following formula may be used to compute the elevation difference h3 between the first and second locations (x1, y1) and (x2, y2) on the road surface 150 measured by the ultrasonic sensors:

h3=(h1−h2)cos θ+d sin θ.

In exemplary embodiments of the present invention, the first ultrasonic sensor 110 and the second ultrasonic sensor 115 are connected to a paver such as a concrete paver; a slip form machine; a form-riding machine; a bridge deck machine; a tow paver, such as a tow-type paver, a tow-behind paver, or a box paver; one or more machines in a paving train, including a spreader or belt placer, a slip form paver, and a curing and texturing machine; a canal lining paver; a cold planar; a road reclaimer; a road trimmer; as well as other vehicles and machines. The first and second ultrasonic sensors 110 and 115 may be adjustably mounted on a paver for identifying surface irregularities without disrupting paving operations. Preferably, the ultrasonic sensors are mounted on a separate vehicle, such as a bridge rig assembly, thus allowing for repeated surface profiles and rapid profiling of a subgrade. Those of skill in the art will appreciate that the sensors may be connected to a variety of vehicles/machines such as an all terrain vehicle (ATV) (see FIG. 31).
In exemplary embodiments of the present invention, the first ultrasonic sensor 110 and the second ultrasonic sensor 115 are connected to a mounting assembly, such as a beam 120. A slope sensor 140 may be connected to the beam, for measuring the slope θ from the horizontal of the line along which the ultrasonic sensors are oriented. The ultrasonic sensors are placed facing the road surface 150, such that they are oriented perpendicular to the beam 120 and have the same angle of incidence relative to the horizontal, slope θ. In this manner, the elevation difference h3 between the first and second locations (x1, y1) and (x2, y2) on the road surface 150 measured by the ultrasonic sensors is computed as described above. Those of skill in the art will appreciate that the first and second ultrasonic sensors 110 and 115 may each have a separate slope sensor and/or utilize various sensors for determining an angle of incidence relative to the horizontal, to account for uneven terrain or the like. Electronic circuitry, mathematical formulae, and techniques may be used to calculate an elevation difference between the first and second locations measured by the ultrasonic sensors using the various angles of incidence.
In a present embodiment, the slope sensor 140 includes a fluid chamber having a gas bubble. By determining a position of the gas bubble with respect to the chamber at a given instant, the slope θ may be determined. However, when a jarring bump is encountered by the smoothness indicator 10, the gas bubble's position may fluctuate and thus not accurately reflect the slope of the beam 120. In embodiments, the rate of change in the position of the gas bubble is measured (for a time period) to ascertain whether the slope determined is accurate.
For example, measurements obtained during a bump may instead utilize a slope determined before or after the bump. In another example, intermediate slope measurements are calculated over the time interval of the bump from slope measurements obtained before and after the bump. These measurements are utilized to calculate intermediate slope measurements, such as by interpolating the various slope measurements. In this manner, slope measurements may more accurately reflect the slope of the beam 120 at a given instant. Other techniques may be used to account for jarring, such as the use of an accelerometer coupled with the beam 120, or the like, for rapidly measuring beam movement.
In one embodiment, the beam 120 connecting the ultrasonic sensors is affixed/secured to a vehicle, which travels over a surface from a first position P1 to a second position P2. In another embodiment, the beam 120 is longitudinally positioned by the vehicle between the first and second positions. For instance, the beam 120 is mounted to a vehicle such that it is translatable from the first position to the second position relative to the vehicle. By using a first elevation difference between a first pair of locations (x1n-1, y1n-1) and (x2n-1, y2n-1), measured by the first and second ultrasonic sensors 110 and 115 at the first position P1, and a second elevation difference between a second pair of locations (x1n, y1n) and (x2n, y2n), measured by the first and second ultrasonic sensors 110 and 115 at the second position P2, a profile of the surface is generated through successive measurements n−1 and n. In this manner, the beam 120 may be moved from the first position to the second position for measuring the profile of the surface.
The incremental slope method is used to construct a surface profile by measuring the slope between successive pairs of points on the surface (e.g. road surface 150) which are separated by a calculable increment. FIG. 12 provides a schematic of the sensor assembly 100, which comprises two sets of non-contacting elevation distance sensors 110 and 115 (for example, Topcon Laser Systems, Inc. sells a model called “Sonic Tracker II” 9142-0000) mounted on a beam 120 a fixed distance, d 130 apart, along with a slope sensor 140 which measures the slope of the beam in the direction of travel. (For example, the slope sensor might be a “System Four Plus Slope Sensor” 9150P/9152P from Topcon Laser Systems, Inc.) The elevation distance sensors may be any non-contacting detector such as ultrasonic or laser sensors. Elevation distance sensor 115 is ahead of elevation distance sensor 110 in a direction of travel the assembly will travel. The elevation profile of road surface 150 to the left (as oriented in FIG. 12) of elevation distance sensor 115 would be known (or estimated).
In the present example, the first and second ultrasonic sensors 110 and 115 use active ultrasonic ranging for measuring distances to a surface, such as distances from the ultrasonic sensors to the road surface 150. Preferably, the ultrasonic sensors have an operating range of 14 to 55 inches, such as to account for a banked curve. However, the first and second ultrasonic sensors 110 and 115 are preferably disposed in a range of 18 to 24 inches to minimize atmospheric impact and the like. Those of skill in the art will appreciate that the sensors should be disposed to minimize atmospheric effects while accommodating lateral height differences.
Preferably, the first and second ultrasonic sensors 110 and 115 are positioned to remain within the desired operating range. An auditory signal such as an audible alarm, a visual indicator such as a flashing light, and/or a mechanical flag may be utilized to alert an operator if a sensor is out of range or nearing a range limit. For instance, various combinations of alerts may be utilized to provide differing levels of warnings. Additionally, a mechanical actuator or the like may be provided for maintaining the beam 120 and/or the first and second ultrasonic sensors 110 and 115 in a desired range. In a further example, a mechanical actuator includes a measuring device for determining translational movement of the beam relative to the vertical direction, and adjusts measurements taken by the first and second ultrasonic sensors 110 and 115 accordingly. In another embodiment, vertical translation of the beam may be controlled by an elevation distance sensor coupled with the smoothness indicator 10 for measuring the height of a string line (which typically correlates to a road surface). Those of ordinary skill in the art will appreciate that various other techniques may be used for maintaining the ultrasonic sensors in a desired range.
Preferably, environmental conditions (such as temperature, etc.) are taken into account during operation. When taking ultrasonic measurements over hot asphalt, for instance, correction and/or adjustment of the data gathered by the first and second ultrasonic sensors 110 and 115 is required to account for temperature variations in hot, localized air through which the distance measurements are taken. For example, a temperature gauge assembly 112, a hydrometer, or the like, may be used to correct measurements to account for the speed of sound through the localized air.
Various methods of determining or estimating the speed of sound through the air between the first and second ultrasonic sensors 110 and 115, and a surface to be profiled, may be utilized as well. For example, measurements of a known distance may be taken periodically and used to calibrate the ultrasonic sensor. Alternatively, the smoothness indicator 10 may include optional/required settings for inputting conditions, such as the type of surface being profiled, the ambient air temperature, and the like. These settings may then be utilized to adjust and/or correct measurements taken by the sensors.
After the elevation difference h3 between a pair of locations (x1, y1) and (x2, y2) measured by the first and second ultrasonic sensors 110 and 115 has been calculated, the elevation difference h3 may be added to or subtracted from a known elevation assigned to one or the other of the pair of locations. For example, if a first elevation y1 has been assigned to the first location (x1, y1) measured by the first ultrasonic sensor 110, the elevation difference h3 is added to the first elevation y1 for calculating a second elevation y2 for the second location (x2, y2) measured by the second ultrasonic sensor 115. If a third elevation y2′ has been assigned to the second location (x2, y2) measured by the second ultrasonic sensor 115, the elevation difference h3 is subtracted from the third elevation y2′ for calculating a fourth elevation y1′ for the first location (x1, y1) measured by the first ultrasonic sensor 110. Thus, by utilizing a known elevation assigned to a location measured by one of the first and second ultrasonic sensors 110 and 115, an elevation for another location measured by the other sensor is calculated. Those of skill in the art will appreciate that the elevations measured and/or calculated for the pair of locations (x1, y1) and (x2, y2) measured by the first and second sensors may be relative to a pre-selected elevation (e.g. a benchmark), related to an absolute elevation, or the like. For example, a GPS measurement may be used as a benchmark, or an elevation input by a user may be assigned to one of the locations (x1, y1) and (x2, y2).
The elevation of the road surface 150 as determined by the forward elevation distance sensor 115 is calculated utilizing the known elevation at the point sensed by rear elevation distance sensor 110. The method is carried out by calculating the vertical distance from the road surface to the rear end of beam 120, then the distance from the rear end of beam 120 to the forward end, then the vertical distance from the forward end of beam 120 to the road surface sensed by the forward sensor 115. The orientation of the sensing apparatus is shown in FIG. 13. In practice, the calculation is as follows:

y2=y1+(h1−h2)cos θ+d sin θ

where the subscript 1 is for the rear sensor, and the subscript 2 is for the forward sensor. The x (horizontal) coordinate for the forward sensor is also required for later reference. This is found by:

x2=x1+(h2−h1)sin θ+d cos θ

The coordinates (x1, y1) and (x2, y2) are depicted in FIG. 13. However, the instantaneous x coordinate of the rear sensor is not immediately known. This may be calculated according to the equation below:




  
    x
    1
    2
  
  =
  
    
      x
      1
      
        n
        -
        1
      
    
    +
    
      Δ
      ⁢
      
        
      
      ⁢
      
        s
        n
      
      ⁢
      
        cos
        ⁡
        
          [
          
            
              1
              2
            
            ⁢
            
              (
              
                
                  θ
                  
                    n
                    -
                    1
                  
                
                +
                
                  θ
                  n
                
              
              )
            
          
          ]
        
      
    
    -
    
      
        (
        
          
            h
            1
            
              n
              -
              1
            
          
          +
          l
        
        )
      
      ⁢
      sin
      ⁢
      
        
      
      ⁢
      
        θ
        
          n
          -
          1
        
      
    
    +
    
      
        (
        
          
            h
            1
            n
          
          +
          l
        
        )
      
      ⁢
      sin
      ⁢
      
        
      
      ⁢
      
        θ
        n
      
    
    +
    
      
        1
        2
      
      ⁢
      
        d
        ⁡
        
          (
          
            
              cos
              ⁢
              
                
              
              ⁢
              
                θ
                
                  n
                  -
                  1
                
              
            
            -
            
              cos
              ⁢
              
                
              
              ⁢
              
                θ
                
                  n
                  -
                  1
                
              
            
          
          )
        
      
    
  




where the superscript n−1 refers to the previous location of beam 120, while superscript n is for the present location of beam 120.
The coordinates (x2, y2) are recorded, the beam 120 translated another increment, Δs 170, and the process repeated until the end of the surface of interest is reached. Interpolation, such as a polynomial spline fit of the data, may be performed to estimate the coordinates of the road surface 150 between the measured points. From the data, roughness indices may be calculated/output. The data may be displayed as a trace or profile.
A result may be calculated, in a fashion analogous to the measurement made by a twenty five foot, eight wheeled profilograph (see FIG. 15). Using the recorded (x, y) data, nine points three feet apart (for instance) are selected or calculated by interpolation. An arithmetic average is taken of eight of the elevations (y values)—all except the elevation for point 5 (y5). Then the vertical distance between point 5 and the average is taken as the profilograph output for point 5 (at x5). A continuous profilograph output may be interpolated between discrete measurement points.
To determine the road surface elevation profile, we begin with a known or estimated road surface elevation profile throughout an initial increment, x0≦x<x0+d cos θ0 where x0 is an arbitrary starting coordinate, and d 130 is the beam length, and θ0 is the initial angle of the beam 120 measured from the horizontal as shown in FIG. 13. Initial angle θ0 is as measured by slope sensor 140.
In the present example, the smoothness indicator 10 measures a surface profile by interleaving a series of discrete profiles measured by the sensor assembly 100. For example, at the start of an elevation profile, the first and second ultrasonic sensors 110 and 115 measure an elevation difference at a first position P1 relative to the road surface 150. A first elevation measurement y1n-1 assigned to the first location is (x1n-1, y1n-1) on the road surface 150, measured by the first ultrasonic sensor 110 (in this case, the trailing sensor relative to the direction of travel); and an elevation difference between the first location (x1n-1, y1n-1) and the second location (x2n-1, y2n-1) on the road surface, measured by the second ultrasonic sensor 115 (in this case, the leading sensor), is added to the first elevation y1n-1 to calculate a second elevation measurement y2n-1 for the second location (x2n-1, y2n-1) on the road surface 150. In embodiments, the first elevation measurement y1n-1 assigned to the first location (x1n-1, y1n-1) measured by the trailing sensor is zero, and it is assumed that the sensor assembly 100 is starting on a level surface. In other embodiments, the smoothness indicator 10 allows the user to enter initial elevation data for the location measured by the trailing sensor. Additionally, GPS data or the like may be utilized to assign an elevation to an initial location measured by the trailing sensor.
The sensor assembly 100 is moved in the direction of travel (e.g. from left to right with respect to FIGS. 12 and 13) an incremental horizontal distance less than or equal to d cos θ0. This increment is denoted Δs 170 as shown in FIG. 14. A travel distance sensor (such as 710, FIG. 1) is utilized to measure the distance traveled by the sensor assembly 100. At this point, rear elevation distance sensor 110 senses the road surface 150 at a location for which the elevation is known (or assumed). Forward elevation distance sensor 115 senses the surface 150 at a new location—one for which the elevation has not yet been calculated.
In order to generate a profile for a surface, the elevation differences are correlated to distances between measurement positions. For example, elevation differences are measured by the first and second ultrasonic sensors 110 and 115 between pairs of locations at first and second positions P1 and P2, along the direction traveled by the sensor assembly 100. In order to determine distances between these positions, an elevation distance sensor is used. For instance, a pulse pickup (PPU) embedded in a drive motor is utilized to measure longitudinal distances between the first and second positions P1 and P2. Alternatively, a separate distance wheel may be included for determining distances between the positions. Those of skill in the art will appreciate that various techniques may be used for determining distances between the first and second positions P1 and P2 as desired.
The first and second ultrasonic sensors 110 and 115 travel longitudinally along a path (e.g. the road) to the second position P2, for generating the surface profile. Upon reaching the second position P2, another set of measurements are obtained. An initial elevation measurement y1n is again assigned to a third location (x1n, y1n) on the road surface 150, measured by the first ultrasonic sensor 110 at the second position P2; and an elevation difference between the third location (x1n, y1n) and a fourth location (x2n, y2n) on the road surface, measured by the second ultrasonic sensor 115 at the second position P2, is added to the initial elevation measurement y1n, as described above, for determining an elevation measurement y2n for the fourth location (x2n, y2n) on the road surface 150. This process is repeated until the sensor assembly 100 has traveled the pre-selected distance d 130, at which point elevation measurements assigned to locations measured by the trailing sensor comprise elevation measurements made by the leading sensor. In further embodiments, the elevation measurements are averaged over distance intervals, and an average elevation measurement for each interval is stored. For example, the elevation measurements are averaged over 2-inch intervals and stored. In this manner, data storage may be minimized. Additionally, the use of elevation measurements averaged over distance intervals may provide a smoothing and filtering effect.
The translating of the sensor assembly 100 may be carried out in several ways, and the present invention is not to be limited to a particular mode of translation. For example, a plurality of sensor assemblies 100 are mounted on the rear of a road paving machine. This permits adjustment of the paving machine as surface variations are detected. Also, variations may be corrected while the concrete is in a plastic state. Referring to FIG. 16, a dedicated rig is employed. Again, a plurality of sensor assemblies 100 are utilized to provide a profile of the road surface, such as the expected lanes traveled by a vehicle's tires.
As discussed, the elevation profile for an initial portion of the surface may be known, estimated, or assumed, such as by utilizing a generally flat section, on the interval x0≦x<x0+d cos θ0.
One of the ways the surface can be obtained in this region is to assume the surface is flat for a distance equal to the distance between the first and second sensors. The difference between the actual elevation at each point and the assumed surface will reappear as errors in the elevation (y values) on each interval following the initial one. There are two options for improving the resulting surface estimate:

    
    
        1. Remove the resulting errors with a low-pass filter by passing the entire elevation profile through a low-pass filter algorithm with a cutoff wavelength longer than d—thus diminishing the error.
        2. Attempt to remove the error by determining a Taylor Series or Fourier Series most highly correlated to the y(x) values in every interval of the surface profile.
    
    


In additional examples, the initial surface is obtained by laying a known flat plate having a length greater than d 130 such that it lies under both elevation distance sensors at the initial location. Deviations from this flat plate are measured.
Obtaining an initial surface elevation profile is depicted in FIG. 17. In this alternative, translation of the sensor assembly occurs over a distance of at least d cos θ0 without movement of the vehicle on which the assembly is mounted, such as by a mechanical actuator/carriage assembly. In this manner, the angle, θ, is unchanging throughout the process. An additional translation sensor (710 of FIG. 1, for instance) to measure the distance traversed must be included in the apparatus. For this approach, the required distance of translation would only be 1⁄2d cos θ0 because both sensors may be utilized. The coordinates of the rear sensor are calculated as follows

x1n=x1n-1+Δsn cos θ

y1n=yn-1+Δsn sin θ+(h1n−h2n)cos θ

where Δs is measured by the additional translation sensor. The superscripts are defined as above. The coordinates for the front sensor are given as

x2n=x1n+d cos θ

y2n=y1n+(h1n−h2n)cos θ+d sin θ

Finally, the beam 120 can be rotated parallel to a (roughly) vertical plane about its center (the actual point of rotation is arbitrary, but for the following analysis, the center is the assumed point of rotation). No translation is to take place during this process. FIG. 18 is a depiction of this method. Let 0 be the initial orientation of the beam, and 1, 2, . . . , n−1, n, . . . , N be successive angles at which discrete measurements are taken.
To determine the rear elevation distance sensor's final location,

    
    
        x11,
    
    


relative to its initial location

    
    
        x10,
    
    


the horizontal distance from the initial location to the beam's center, then back to the final location, is calculated. Referring to FIG. 18 for nomenclature, the location of

    
    
        x11 
    
    


is calculated as:




  
    x
    1
    1
  
  +
  
    x
    1
    0
  
  -
  
    
      (
      
        
          h
          1
          0
        
        +
        l
      
      )
    
    ⁢
    sin
    ⁢
    
      
    
    ⁢
    
      θ
      0
    
  
  +
  
    
      (
      
        
          h
          1
          1
        
        +
        l
      
      )
    
    ⁢
    sin
    ⁢
    
      
    
    ⁢
    
      θ
      1
    
  
  +
  
    
      1
      2
    
    ⁢
    
      d
      ⁡
      
        (
        
          
            cos
            ⁢
            
              
            
            ⁢
            
              θ
              0
            
          
          -
          
            cos
            ⁢
            
              
            
            ⁢
            
              θ
              1
            
          
        
        )
      
    
  




The corresponding y location,

    
    
        y11,
    
    


relative to the initial y location,

    
    
        y10,
    
    


is determined calculating the vertical distance from the initial location to the beam's center, then back to the final location, thus:




  
    y
    1
    1
  
  =
  
    
      y
      1
      0
    
    -
    
      
        (
        
          
            h
            1
            0
          
          +
          l
        
        )
      
      ⁢
      sin
      ⁢
      
        
      
      ⁢
      
        θ
        0
      
    
    +
    
      
        (
        
          
            h
            1
            1
          
          +
          l
        
        )
      
      ⁢
      sin
      ⁢
      
        
      
      ⁢
      
        θ
        1
      
    
    +
    
      
        1
        2
      
      ⁢
      
        d
        ⁡
        
          (
          
            
              cos
              ⁢
              
                
              
              ⁢
              
                θ
                0
              
            
            -
            
              cos
              ⁢
              
                
              
              ⁢
              
                θ
                1
              
            
          
          )
        
      
    
  




At the same time, the rear sensor 110 can be measuring the road surface as the beam is rotated. The coordinates when θ=θ0 are calculated thus:

x20=x10+(h20−h10)sin θ0+d cos θ0 

y20=y10+(h10−h20)cos θ0+d sin θ0 

Then, as the beam is rotated, the coordinates from both sensors are calculated as:



  
    
      x
      1
      n
    
    =
    
      
        x
        1
        
          n
          -
          1
        
      
      +
      
        
          (
          
            
              h
              1
              
                n
                -
                1
              
            
            +
            l
          
          )
        
        ⁢
        sin
        ⁢
        
          
        
        ⁢
        
          θ
          
            n
            -
            1
          
        
      
      +
      
        
          (
          
            
              h
              1
              n
            
            +
            l
          
          )
        
        ⁢
        sin
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
      +
      
        
          1
          2
        
        ⁢
        
          d
          ⁡
          
            (
            
              
                cos
                ⁢
                
                  
                
                ⁢
                
                  θ
                  
                    n
                    -
                    1
                  
                
              
              -
              
                cos
                ⁢
                
                  
                
                ⁢
                
                  θ
                  n
                
              
            
            )
          
        
      
    
  




  
    
      x
      2
      n
    
    =
    
      
        x
        1
        n
      
      +
      
        
          (
          
            
              h
              2
              n
            
            -
            
              h
              1
              n
            
          
          )
        
        ⁢
        sin
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
      +
      
        d
        ⁢
        
          
        
        ⁢
        cos
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
    
  




  
    
      y
      1
      n
    
    =
    
      
        y
        1
        
          n
          -
          1
        
      
      +
      
        
          (
          
            
              h
              1
              
                n
                -
                1
              
            
            +
            l
          
          )
        
        ⁢
        cos
        ⁢
        
          
        
        ⁢
        
          θ
          
            n
            -
            1
          
        
      
      +
      
        
          (
          
            
              h
              1
              n
            
            +
            l
          
          )
        
        ⁢
        cos
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
      +
      
        
          1
          2
        
        ⁢
        
          d
          ⁡
          
            (
            
              
                sin
                ⁢
                
                  
                
                ⁢
                
                  θ
                  
                    n
                    -
                    1
                  
                
              
              -
              
                sin
                ⁢
                
                  
                
                ⁢
                
                  θ
                  n
                
              
            
            )
          
        
      
    
  




  
    
      y
      2
      n
    
    =
    
      
        y
        1
        n
      
      +
      
        
          (
          
            
              h
              2
              n
            
            -
            
              h
              2
              n
            
          
          )
        
        ⁢
        cos
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
      +
      
        d
        ⁢
        
          
        
        ⁢
        sin
        ⁢
        
          
        
        ⁢
        
          θ
          n
        
      
    
  



In the foregoing manner, an elevation profile is an interleaved series of discrete profiles. For instance, if elevation measurements are determined for pairs of locations at two-inch intervals, and the ultrasonic sensors are spaced three feet apart, 18 discrete profiles will be generated and interleaved together. Thus, elevation measurements for any two locations spaced two inches apart will be independent of each other. Those of skill in the art will appreciate that the spacing of the first and second ultrasonic sensors 110 and 115, the distance between measurements taken by the sensors, and the number of discrete profiles generated may vary as desired.
Because the surface profile generated by the smoothness indicator 10 is an interleaved series of discrete profiles, it will be appreciated that random errors introduced in the course of measuring elevation differences between series of locations will propagate, accumulating to form errors for the interleaved series of discrete profiles which may exceed errors for the elevation measurements of a single profile. Those of ordinary skill in the art will appreciate that this may generate an error band for the interleaved series of measurements larger than that for a single profile.
In exemplary embodiments, an incremental spatial filter is applied when generating a surface profile. For example, a single-pole low-pass spatial filter is utilized to generate a filtered profile of the surface (such as a spatial filter utilizing a nine-inch length constant). For example, a series of elevation differences are measured by the first ultrasonic sensor 110 and the second ultrasonic sensor 115, and the elevation differences are used to calculate an average elevation measurement over an initial two-inch interval. The average elevation measurement for the initial two-inch interval is then filtered, such as by comparing it to an elevation measurement for a second two-inch interval adjacent to the initial interval. In the current example, a surface profile is post-filtered, or filtered upon completion of the profile's elevation measurements; while in another embodiment, the surface profile is incrementally filtered, wherein each new elevation measurement for the profile is filtered before being stored. Those of skill in the art will appreciate that other filters may be used to alter, correct, and/or modify elevation measurements, for increasing the relative accuracy of the measurements, without departing from the scope and intent of the present invention.
Surface profile data measured by the smoothness indicator 10 may be used for deriving information about a surface. In exemplary embodiments, the surface profile data is used to identify a must-grind bump, a bump which must be reduced and/or eliminated from the surface (e.g. to meet construction specifications). For example, the smoothness indicator 10 may use hardware and/or software installed in an information handling system device, such as a portable computer assembly, to identify a must-grind bump. In embodiments, the smoothness indicator 10 includes a mechanical assembly for marking or identifying the must-grind bump, such as by painting a mark at the location of the bump. Other techniques may be used to identify a must-grind bump as desired. Additionally, other surface irregularities may be noted, such as low spots.
An advantage of the present system is that a surface irregularity may be indicated and corrected while the road surface 150 is still in a plastic state. It will be appreciated that a dedicated smoothness indicator 10 may be used to identify a surface irregularity, such as a must grind bump; and the bridge rig assembly 12 may be reversed to allow for smoothing of the road surface 150. Upon smoothing and/or elimination of the irregularity, the smoothness indicator 10 may be moved over the feature to verify that it has been reduced and/or eliminated and to provide a profile of the corrected segment. This process may be repeated as required. In exemplary embodiments of the present invention, surface profile data acquired for the surface irregularity before it has been reduced and/or eliminated is replaced by data from a second pass, a third pass, or another pass over the irregularity. In this manner, data stored by the smoothness indicator reflects the actual surface profile of the road surface 150, such as for a 1/10 mile road segment. However, it is contemplated that initial measurement data for the feature may be retained by the smoothness indicator 10 for measuring the effectiveness of the corrective operation, for personnel training or the like.
In another embodiment, a surface profile is taken of the road surface 150, and elevation measurements determined for the surface are stored by the smoothness indicator, such as by a Random Access Memory (RAM), a Read-Only Memory (ROM), a magnetic diskette, and/or removable media, such as a floppy disk. These elevation measurements may be utilized to determine must-grind bumps or other surface irregularities upon completion of the elevation profile. In combination with station marker data, which may be stored along with elevation measurements, the stored data may be retrieved and examined, such as by hardware or software, to identify must-grind bumps. An operator may identify the bumps via station marker data, location data, or other data stored as part of the surface profile, for identifying the location of the surface irregularity. Those of skill in the art will appreciate that other information may be determined upon completion of the profile, such as low spots, Profile Index data, International Roughness Index data, Gomaco Smoothness Index data, or the like.
The surface profile data is analyzed to provide data in various formats. In embodiments, surface profile measurements are utilized to produce a simulated profilograph output (FIG. 15). For example, a California Profilograph output may be generated. Additionally, Profile Index values may be calculated. Measurements may also be utilized to calculate International Roughness Index values, which simulate travel of a theoretical “golden car” over the road surface 150. Typically, index values such as Profile Index values and International Roughness Index values are computed for set intervals, such as between station markers. Another advantage of the smoothness indicator 10 of the present invention is that it allows for the calculation of index values, such as Gomaco Smoothness Index values, over a user-defined interval, such as an interval of one-tenth of a mile, for instance. Additionally, the user-defined interval may be centered on any point within the profile. Those of skill in the art will appreciate that surface profile measurements may be formatted in a wide variety of ways.
Referring now to FIG. 19, a method 200 for determining an elevation profile in accordance with an embodiment is described. In step 202, a first non-contact elevation distance sensor, such as the first ultrasonic sensor 110, measures a first distance to a surface, such as the distance h1 to the road surface 150, at a first location, such as the location (x1, y1). In step 204, a second non-contact elevation distance sensor, such as the second ultrasonic sensor 115, measures a second distance to the surface, such as the distance h2 to the road surface 150, at a second location, such as the location (x2, y2). In step 206, a first angle of incidence for the first ultrasonic sensor 110 relative to a horizontal plane is determined, such as by measuring angle θ using slope sensor 140. Then, in step 208, a second angle of incidence for the second ultrasonic sensor 115 relative to the horizontal is determined (such as by measuring angle θ using slope sensor 140). In step 210, an elevation difference, such as elevation difference h3, is calculated between the first and second locations, using the first and second distances and the first and second angles of incidence. Next, in step 212, the first location (x1, y1) along the road surface 150 is calculated using the first distance and the first angle of incidence. Likewise, in step 214, the second location (x2, y2) along the road surface 150 is calculated using the second distance and the second angle of incidence. Finally, in step 216, the elevation of the second location (x2, y2) is calculated using an elevation assigned to the first location (x1, y1), for generating an elevation profile of the road surface.
Referring to FIG. 20, a smoothness indicator 250 in accordance with an exemplary embodiment of the present invention is described. The smoothness indicator 250 includes a first elevation distance sensor 252, a second elevation distance sensor 254, a slope sensor 256, a travel distance sensor 258, a feedback and actuator assembly 260 coupled with a wheel 262, and a processor 264 coupled with a memory 266, interconnected in a bus architecture 268. The first and second elevation distance sensors 252 and 254 are non-contact sensors, such as ultrasonic sensors, laser sensors, or the like. In one embodiment, the first and second elevation distance sensors are ultrasonic sensors, and they communicate measurements to the processor forty times per second. The slope sensor 256 is for measuring a slope from a horizontal plane of a line along which the ultrasonic sensors 252 and 254 are oriented. The travel distance sensor 258 is for measuring distances traveled, such as distances traveled by the wheel 262. The feedback and actuator assembly 260 uses control logic for controlling the wheel 262 via an actuator assembly. The processor 264 uses distance measurements taken by the first and second elevation distance sensors 252 and 254, in combination with slope measurements taken by the slope sensor 256, to calculate elevation differences between locations on a surface, such as the road surface 150 (FIG. 1). Additionally, the processor 264 communicates with the memory 266, storing and retrieving elevation measurements for calculating smoothness index values, Profile Index (PI) values, International Roughness Index (IRI) values, and other elevation measurements and indices. The processor 264 may also provide input to the feedback and actuator assembly 260. For example, the processor may be coupled with a contact sensor or an elevation distance sensor for tracking the location of a string line and moving the smoothness indicator 250 accordingly. Those of ordinary skill in the art will appreciate that a smoothness indicator may use various components without departing from the scope and intent of the present invention.
Referring generally to FIGS. 21 through 29, a graphical user interface 300 for the smoothness indicator 10 is described. The graphical user interface 300 may be displayed on a portable information handling system device, such as a personal computer, a dedicated processing assembly, or another similar machine.
Referring to FIG. 21, a sensor and encoder setup screen 302 is described. The sensor and encoder setup screen 302 includes radio/selection buttons 304 for selecting English and/or metric units. A number of text entry boxes 306 may be included for allowing an operator to input the distances of sensor assemblies 100 relative to a wheel of the bridge rig assembly 12, such as a wheel 16 (FIG. 1), or the like. A second text entry box 308 is provided for entering the position of a control line relative to the wheel. A third text entry box 310 is provided for inputting the distance between wheels of the bridge rig assembly 12. Load and save buttons 312 are also included for recording and/or recalling information entered in the text boxes 306, 308, and 310. Other text entry boxes may be included for recording parameters for the smoothness indicator 10 and the like.
Referring now to FIG. 22, a job information screen 314 is described in accordance with an exemplary embodiment of the present invention. The job information screen 314 may include text entry boxes 316 for entering information about a particular profile, a particular job for which a profile is to be generated, and other information as desired. Information entered in the job information screen 314, may be stored and/or recorded with a surface profile to aid identification.
Referring to FIGS. 23 through 25, exemplary trace displays 318 are described. In embodiments, the trace displays 318 allow a user to dynamically view surface profile information from one or more elevation profiles. The trace displays 318 display surface profile data in graphical form such as by placing the data on a scale or the like. Indicators such as dashed lines may be superimposed on a trace 320, for indicating station markers relative to points on the trace 320. The trace displays 318 may include a slider bar 322, forward and reverse buttons, or similar functionality, for allowing an operator of the smoothness indicator 10 to observe surface profile data as desired. In this case, radio/selection buttons 324 are provided for selecting a real time display of a surface profile or allowing the operator to view the history of the surface profile. Other information such as a file name, a job description, or other identifying information may be included for identifying a surface profile. Two or more traces 320 may be displayed on the trace displays 318 at one time. For example, a first trace 320 may be located above a second trace 320 for comparison purposes. Alternatively, the first trace 320 may be superimposed in front of, or behind, the second trace 320. The traces 320 may be displayed in various formats without departing from the scope of the present invention.
Referring now to FIG. 26, a measurement options screen 326 in accordance with an exemplary embodiment is described. The measurement options screen 326 includes text entry boxes 328 for entering Profile Index parameters, text entry boxes 330 for entering International Roughness Index parameters, text entry boxes 332 for entering bump detection parameters, and text entry box 334 for entering smoothness index parameters. The text boxes 328, 330, 332, and 334, may be used to enter relevant measurement information for calculating Profile Index data, International Roughness Index data, and smoothness index data. Additionally, these text boxes may be used for defining parameters for activating a bump alarm or another similar indication of a bump. Those of skill in the art will appreciate that various other parameters may be included on the measurement options screen 326 without departing from the scope and intent of the present invention. Load and save buttons 336 are also included for recording and/or recalling information entered in the text boxes 328, 330, 332, and 334.
Referring to FIG. 27, a bump alarms options screen 338 is described in accordance with exemplary embodiments of the present invention. Check boxes 340 are provided for allowing an operator of the smoothness indicator 10 to selectively determine the functionality of an alarm/series of alarms. Various options may be provided for different types of alarms. Additionally, options for controlling a marking (e.g. a visual cue such as a paint sprayer) may be included on the bump alarm options screen 338.
Referring now to FIG. 28, a Profile Index report screen 342 is described. The Profile Index report screen 342 includes radio/selection buttons 344 for allowing an operator of the smoothness indicator 10 to view Profile Index report information 346. The Profile Index report information 346 is calculated by the smoothness indicator 10, and displayed according to a radio/selection button 344 selected by the user. Additionally, text boxes 348 are included for entering parameters for calculating the Profile Index report information 346. These text boxes 348 may allow entry for information such as minimum scallop height, minimum scallop width, segment length, scallop resolution, blanking band, and the like. Those of ordinary skill in the art will appreciate that other various parameters for calculating the Profile Index report information 346 may be included without departing from the scope and intent of the present invention.
Referring now to FIG. 29, an International Roughness Index report screen 350 is described in accordance with exemplary embodiments of the present invention. The International Roughness Index report screen 350 includes radio/selection buttons 352 for allowing an operator of the smoothness indicator 10 to view International Roughness Index report information 354. The International Roughness Index report information 354 is calculated by the smoothness indicator 10, and displayed according to a radio/selection button 352 selected by the user. Additionally, a text box 356 is included for entering parameters for calculating the International Roughness Index report information 354. The text box 356 may be provided along with other text boxes for entry of information such as segment length, and the like. Various parameters for calculating the International Roughness Index report information 354 may be included without departing from the scope and spirit of the present invention.
Referring to FIGS. 30 and 31, a smoothness indicator 10 including one or more sensor assemblies 100, like the embodiments illustrated in FIGS. 1 through 7, is described in accordance with further exemplary embodiments. The smoothness indicator 10 includes a bridge rig 12 having a cantilevered arm 13. The cantilevered arm 13 may be extended over a surface 150 for profiling the surface. For instance, the cantilevered arm may be folded and/or stowed alongside the rig 12 for transport, and extended for profiling a surface. The sensor assemblies 100 are positioned for measuring locations upon the surface 150, such as where automobile tires may travel upon the surface. In a first embodiment, the sensor assemblies 100 may be manually positioned. Alternatively, a drive assembly may be utilized for automatically adjusting a sensor assembly 100 to a pre-selected position.
The smoothness indicator 10 may include a height adjustment assembly 14, such as an assembly including a hydraulic piston, a mechanical linkage, or the like, for adjusting the height of the smoothness indicator 10 and positioning a sensor assembly 100 a distance from the surface 150. This may be desirable for maintaining the sensor assembly in an optimal range while profiling the surface. In further embodiments, the smoothness indicator 10 transmits a command to the height adjustment assembly 14 to position a sensor assembly 100 at a specified distance from the surface 150.
The smoothness indicator 10 may include a travel distance sensor 710 connected to a wheel 16 of the smoothness indicator. The travel distance sensor 710 measures distances traveled by the wheel of the smoothness indicator to determine distances traveled by a sensor assembly 100. In embodiments, two or more travel distance sensors are included for determining distances over non-linear terrain, such as distances around a sweeping highway curve. In a further example, a distance measuring wheel may be included with the smoothness indicator 10 for determining distances traveled by a sensor assembly 100.
In further embodiments, the smoothness indicator 10 includes one or more contact sensors 18. A contact 20 is included for measuring a distance between the smoothness indicator 10 and a guide, such as a string line positioned for guiding a paver, or the like. For example, a contact sensor 18 may follow a string line 22 for automatically directing the smoothness indicator 10 when measuring a surface profile. The contact 20 follows the string line as the smoothness indicator advances over the surface 150. By analyzing movement of the contact 20, the smoothness indicator positions the smoothness indicator 10 for travel in a direction following the direction of the surface. In another embodiment, an elevation distance sensor assembly is utilized to guide the smoothness indicator by tracking a line, which may be rope or another type of line detectable by the elevation distance sensor.
A feedback and actuator assembly may be utilized to control the wheel 16 of the smoothness indicator 10. The feedback and actuator assembly may include a feedback sensor (such as a rotary potentiometer, or the like, for sensing an angle of the wheel 16), an actuator, and/or a control assembly, for guiding the angle of the wheel 16, controlling its rotational velocity, and/or directing another characteristic of the wheel's movement. The feedback and actuator assembly may be coupled with the contact sensor 18 (or the elevation distance sensor) for controlling the direction of travel of the smoothness indicator 10. Alternatively, the smoothness indicator and/or the wheel are controlled by a Local Positioning System (LPS) (e.g. a robotic total station), a Global Positioning System (GPS), or the like, for directing the smoothness indicator. In this manner, the smoothness indicator 10 may travel a predetermined course.
Referring now to FIG. 31, the surface 150 over which the cantilevered arm 13 is extended may comprise a subgrade. A sensor assembly 100 is positioned for measuring locations upon the subgrade, such as for determining the thickness of pavement to be constructed upon the subgrade. Thus, the smoothness indicator 10 may be utilized to check the subgrade. For example, the smoothness indicator may be correlated to a line detected by an elevation distance sensor for determining a percentage yield for a paving material such as concrete. Alternatively, the contact sensor 18 may be used to compare the string line 22 to the subgrade. For instance, string line used by a paver for determining the thickness of a paved surface, such as a road surface, may be compared to the subgrade for determining pavement thickness at various locations and minimizing surface inconsistencies which reduce the percentage yield. In such a case, the contact sensor 18 may be replaced by an elevation distance sensor or the like as needed.
It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof, it is the intention of the following claims to encompass and include such changes.

## Claims

1. An apparatus, comprising:
a bridge rig for spanning a road surface, the bridge rig having a first wheel and a second wheel;
a plurality of non-contact elevation distance sensors supported by the bridge rig for measuring distances to the road surface at a plurality of locations along the road surface;
a slope sensor supported by the bridge rig for measuring an angle of incidence of the plurality of non-contact elevation distance sensors relative to a horizontal plane;
a height adjustment assembly coupled with the bridge rig, the height adjustment assembly configured for adjusting a height of the bridge rig above the road surface and for adjusting a height of the plurality of non-contact elevation distance sensors above the road surface, the height adjustment assembly responsive to an input to adjust the height of the plurality of non-contact elevation distance sensors above the road surface;
a first travel distance sensor connected to the first wheel of the bridge rig for measuring a first travel distance for the first wheel of the bridge rig; and
a second travel distance sensor connected to the second wheel of the bridge rig for measuring a second travel distance for the second wheel of the bridge rig,
wherein the distances measured by the plurality of non-contact elevation distance sensors and the angle of incidence measured by the slope sensor are utilized to generate an elevation profile of the road surface for the plurality of locations along the road surface, and the plurality of locations along the road surface measured by each of the plurality of non-contact elevation distance sensors are determined at least in part by calculating a weighted average utilizing the first travel distance and the second travel distance.

2. The apparatus of claim 1, wherein the weighted average calculated utilizing the first travel distance and the second travel distance represents a position at least substantially approximating the location of an automobile tire along the road surface.

3. The apparatus of claim 1, wherein at least one of the first travel distance sensor or the second travel distance sensor comprises a pulse pickup embedded in a drive motor.

4. The apparatus of claim 1, wherein at least one of a Profile Index value, an International Roughness Index value, or a California Profilograph value are calculated for the road surface utilizing the generated elevation profile.

5. The apparatus of claim 1, wherein a smoothness index value is calculated for a user-defined interval for the road surface utilizing the generated elevation profile.

6. The apparatus of claim 1, wherein the plurality of non-contact elevation distance sensors comprises an ultrasonic sensor.

7. The apparatus of claim 1, further comprising a transmitter for transmitting information regarding the elevation profile of the road surface.

8. A system, comprising:
a bridge rig for spanning a road surface, the bridge rig having a first wheel and a second wheel;
a plurality of non-contact elevation distance sensors supported by the bridge rig for measuring distances to the road surface at a plurality of locations along the road surface;
a slope sensor supported by the bridge rig for measuring an angle of incidence of the plurality of non-contact elevation distance sensors relative to a horizontal plane;
a first travel distance sensor connected to the first wheel of the bridge rig for measuring a first travel distance for the first wheel of the bridge rig;
a second travel distance sensor connected to the second wheel of the bridge rig for measuring a second travel distance for the second wheel of the bridge rig;
a processor connected to the plurality of non-contact elevation distance sensors, the slope sensor, the first travel distance sensor, and the second travel distance sensor; and
control programming for execution by the processor operatively configured to generate an elevation profile of the road surface for the plurality of locations along the road surface utilizing the distances measured by the plurality of non-contact elevation distance sensors and the angle of incidence measured by the slope sensor,
wherein the plurality of locations along the road surface measured by each of the plurality of non-contact elevation distance sensors are determined at least in part by calculating a weighted average utilizing the first travel distance and the second travel distance.

9. The system of claim 8, wherein the weighted average calculated utilizing the first travel distance and the second travel distance represents a position at least substantially approximating the location of an automobile tire along the road surface.

10. The system of claim 8, wherein at least one of the first travel distance sensor or the second travel distance sensor comprises a pulse pickup embedded in a drive motor.

11. The system of claim 8, wherein at least one of a Profile Index value, an International Roughness Index value, or a California Profilograph value are calculated for the road surface utilizing the generated elevation profile.

12. The system of claim 8, wherein a smoothness index value is calculated for a user-defined interval for the road surface utilizing the generated elevation profile.

13. The system of claim 8, wherein the plurality of non-contact elevation distance sensors comprises an ultrasonic sensor.

14. The system of claim 8, further comprising a transmitter for transmitting information regarding the elevation profile of the road surface.

15. A method, comprising:
spanning a road surface;
positioning a first wheel on a first side of the road surface;
positioning a second wheel on a second side of the road surface;
supporting a plurality of non-contact elevation distance sensors over the road surface for measuring distances to the road surface at a plurality of locations along the road surface;
adjusting a height of the plurality of non-contact elevation distance sensors over the road surface based on a median of the height of each of the plurality of non-contact elevation distance sensors over the road surface in response to a command input;
measuring an angle of incidence of the plurality of non-contact elevation distance sensors relative to a horizontal plane;
measuring a first travel distance for the first wheel;
measuring a second travel distance for the second wheel;
generating an elevation profile of the road surface for the plurality of locations along the road surface utilizing the distances measured by the plurality of non-contact elevation distance sensors and the angle of incidence; and
determining the plurality of locations along the road surface measured by each of the plurality of non-contact elevation distance sensors at least in part by calculating a weighted average utilizing the first travel distance and the second travel distance.

16. The method of claim 15, wherein the weighted average calculated utilizing the first travel distance and the second travel distance represents a position at least substantially approximating the location of an automobile tire along the road surface.

17. The method of claim 15, wherein measuring at least one of the first travel distance or the second travel distance comprises measuring a travel distance utilizing a pulse pickup embedded in a drive motor.

18. The method of claim 15, wherein at least one of a Profile Index value, an International Roughness Index value, or a California Profilograph value are calculated for the road surface utilizing the generated elevation profile.

19. The method of claim 15, wherein a smoothness index value is calculated for a user-defined interval for the road surface utilizing the generated elevation profile.

20. The method of claim 15, wherein the plurality of non-contact elevation distance sensors comprises an ultrasonic sensor.

21. The system of claim 8, further comprising a height adjustment assembly coupled with the bridge rig, the height adjustment assembly configured for adjusting a height of the bridge rig above the road surface and for adjusting a height of the plurality of non-contact elevation distance sensors above the road surface, the height adjustment assembly responsive to an input to adjust the height of the plurality of non-contact elevation distance sensors above the road surface.

22. The system of claim 8, wherein the bridge rig is configured for at least one of extension or retraction of a width of the bridge rig in a direction approximately perpendicular to a direction of travel of the bridge rig.

23. An apparatus, comprising:
a bridge rig for spanning a road surface;
a plurality of non-contact elevation distance sensors supported by the bridge rig for measuring distances to the road surface;
a height adjustment assembly coupled with the bridge rig, the height adjustment assembly configured for adjusting a height of the bridge rig above the road surface and for adjusting a height of the plurality of non-contact elevation distance sensors above the road surface, the height adjustment assembly responsive to an input to adjust the height of the plurality of non-contact elevation distance sensors above the road surface;
a slope sensor supported by the bridge rig for measuring an angle of incidence of the plurality of non-contact elevation distance sensors relative to a horizontal plane; and
a marker for marking a signal indicating a smoothness of the road surface,
wherein the measured distances and the angle of incidence are utilized to generate an elevation profile of the road surface including the smoothness of the road surface.

24. The apparatus of claim 23, wherein the signal indicates a surface irregularity.

25. The apparatus of claim 24, wherein the surface irregularity comprises at least one of a must-grind bump or a low spot.

26. The apparatus of claim 23, wherein the signal comprises information regarding a possible correction for the surface irregularity.

27. The apparatus of claim 23, wherein the signal comprises a painted mark near the location of the surface irregularity.

28. The apparatus of claim 27, wherein the painted mark comprises visual information regarding a possible correction for the surface irregularity.