Geometrical instruments – Gauge – Straightness – flatness – or alignment
Reexamination Certificate
2002-12-05
2004-08-17
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Gauge
Straightness, flatness, or alignment
C033S775000
Reexamination Certificate
active
06775914
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to surveying instruments. More specifically the invention relates to a rolling, contact-based, surface profiler for determining the contour and characteristics of a surface. Such apparatus are useful in a number of industries and applications, most notably in the construction and maintenance of roads, aviation runways, bridges, buildings and other structures.
BACKGROUND OF THE INVENTION
Surface profiling methods include either non-contact methods using optical (e.g. laser) and ultrasonic transducers, or contact-based methods using ground-engaging pads or wheels.
Contact-based profilers are generally either of the “walking” or the rolling type. So-called “walking” profilers include those having spaced ground-engaging pads that are alternately brought into engagement with the surface across the distance to be measured. However, the majority of contact-based profilers are of the rolling type. Rolling profilers travel on wheels over the surface to be profiled. They may be manually propelled by a walking operator, or driven or towed by a vehicle.
Rolling profilers may in turn generally be characterized as being of the type where the profiler's supporting wheels are not connected to the transducer (typically with an inclinometer or a pendulum measuring the inclination of the entire profiler's frame) or of the type having separate marker or sensing wheels that do not support the profiler but are connected to a transducer for direct sensing of the position of the marker wheel in relation to the supporting wheels. A relatively common prior art approach for rolling profiling apparatus of the latter type is to provide load bearing wheels at the front and rear ends of a frame and ground-engaging sensing means mounted between the load bearing wheels. Such apparatus is exemplified by U.S. Pat. No. 5,535,143 to Face.
In surface profiling, a surface contour or “profile” is acquired by making measurements at constant distance intervals of the elevation along the surface, relative to a starting elevation. Sampling of elevation in this manner produces a mathematical series of elevations, which collectively represent the physical surface. The elevation series can be used for a number of purposes relating to construction or ongoing management of the surface.
Various mathematical algorithms can be applied to the series to calculate indices that are representative of the roughness or smoothness of the surface. The “roughness” relates to the discomfort that would be experienced by a passenger riding in a real or simulated vehicle that rolls over the surface. One of these indices, by way of example, is the International Roughness Index (IRI), that models the suspension of a nominal quarter of an automobile that is rolled over the surface within a computer model. The IRI algorithm computes the total travel of the quarter car's suspension per unit of distance traveled while rolling over the subject profile—the greater the travel, the higher the IRI value or roughness.
IRI is increasingly being used for surface construction contract management. The quality of a newly constructed surface is compared to its contractual end product specification to determine if the finished or “end product” surface is compliant with the specification. Construction contracts can be managed using surface profilers with contract bonuses and penalties payable depending on profile test results. IRI is coming into use as the preferred index being used to determine profile quality. It should be apparent that instruments used to acquire the elevation series representing the actual surface profile that are used as input for calculation of the IRI must therefore have high accuracy and repeatability.
IRI is also being used for management of large-scale networks of roads within the jurisdictions of state departments of transport and highways, where non-contact surface profilers capable of collecting data at highway speeds are commonly being used. These are typically inertial profilers that measure elevation with reference to an inertial reference contained within a computer model. Due to their inherent limitations, such inertial profilers must be calibrated or verified against a benchmark reference or a more accurate profiling instrument to validate the data they acquire.
As the accuracy of any rolling contact-based profiler depends on maintaining continuous contact between the profiler and the surface to be profiled, the more accurate rolling profilers tend to be those that are manually operated at relatively low speeds so that the characteristics of the surface can be fully captured. While the accuracy of such devices is generally higher, the rate of data collection using contact devices has generally been too slow.
Prior art rolling devices, travelling at speeds approaching normal human walking speed of about 2.5 mile per hour, begin to lose contact with the surface to be profiled, particularly when travelling over holes or bumps. As a result, the operator must restrict the speed of the profiler to avoid bouncing it and such profilers require substantial time to collect data, requiring the operator to remain in the field for extended periods. This in turn subjects the operator to risks from the traffic in the area being surveyed. In addition, despite care being taken by the operator to avoid bounce, the accuracy of some of these devices is still less than ideal.
It is therefore an object of the present invention to provide a rolling profiler having improved accuracy and increased speed of data acquisition. More specifically, it is an object of the present invention to provide such improved accuracy and increased speed in a rolling profiler wherein the transducer measures the inclination of the entire profiler frame.
It is known to provide, in a rolling profiler, a suspension system between load bearing wheels and the frame of the profiler, which supports inclinometer transducer means, in a manner analogous to a conventional vehicle suspension. Such a system is disclosed for example in U.S. Pat. No. 3,882,607 to Plasser et al. in a rail profiling car. The effect of such a suspension is to smooth out the ride of the frame. However, where the transducer measures the inclination of the frame, this results in an averaging of the profile data and detracts from the accuracy of the profile.
It is desirable to provide a means for maintaining the supporting wheels of the profiler in continuous contact with the surface but to do so by means of a bias system that nonetheless allows the frame to fully track the vertical displacement of the wheels caused by discontinuities in the surface being profiled.
It is further known to provide a handle to allow an operator to propel a manual rolling profiler. Such handles are disclosed in U.S. Pat. No. 3,026,164 to Lancerini and U.S. Pat. No. 5,107,598 to Woznow et al. It will be noted that such prior art handles are typically either rigidly mounted at the rear end of the profilers or are pivoted high above the wheel axles. However, such arrangements subject the frame of the profiler to an unbalanced vertical force as a result of the propulsion and manipulation (pushing and pulling) by the operator of the handle. This unbalanced vertical force on the frame skews the derived profile data.
It is therefore a further object of the present invention to provide a handle arrangement that minimizes the imbalance imposed on the frame as a result of manipulation by the operator.
With the higher accuracy and higher speed of operation contemplated by the present invention, it is possible to operate the profiler at speeds greater than the normal walking speed of an operator. It is therefore desirable to provide means for converting the profiler from a manual mode to a driven mode.
The foregoing and other objects of the invention will be appreciated by reference to the summary and detailed description of the preferred embodiment that follow.
SUMMARY OF THE INVENTION
The surface profiling apparatus to which the invention relates comprises a frame, whe
Fulton Christopher W.
Glenn Michael A.
Glenn Patent Group
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