Measuring and testing – Tire – tread or roadway – Tire inflation testing installation
Patent
1991-01-14
1994-01-25
Woodiel, Donald O.
Measuring and testing
Tire, tread or roadway
Tire inflation testing installation
73105, G01B 728
Patent
active
052807193
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for measuring roughness along the surface of a traffic area, e.g. a road or an airport runway.
More specifically, the invention concerns measuring the longitudinal dimension of the road, i.e. along a "wheel track", and not transverse to the road (for instance in order to measure the transverse profile of the wheel track).
2. State of the Prior Art
Previously known techniques for measuring roughness or evenness along a road track mainly comprise mechanical sensing techniques. During recent years optical techniques have also been put into use. For example, U.S. Pat. No. 4,653,316 discloses a vehicle comprising two attached laser devices longitudinally spaced in relation to each other, which devices emit light beams perpendicularly down towards the road surface. The light spots are read by corresponding detectors (focus detection).
U.S. Pat. No. 4,685,806 discloses a system in which stationary laser sources generate vertical and horizontal laser planes as a reference for a vehicle, which vehicle is equipped with "laser cameras" or the like, i.e. a transverse row of lasers/detectors or possibly ultrasound transducers directed down towards the road surface. A two-dimensional type mapping along the road track is thereby achieved, but the use of additional lasers for defining e.g. a horizontal plane is expensive and time-consuming.
SUMMARY OF THE INVENTION
The present invention utilizes only one single row of ultrasound transducers, which feature involves cost savings in relation to laser devices. Furthermore, the requirement for fixed reference planes is eliminated when the present invention is put into use, and the measurements can be made quickly and reliably.
In accordance with the present invention, this is achieved by adopting a method for measuring surface roughness along a longitudinal dimension of a traffic area, e.g. along a road. In the method a measuring apparatus is carried during use by a vehicle or a carriage trailing behind a vehicle, wherein control means (or control), an energizing means (or energizer) and a recording means (or a recorder) for executing the measurements, as well as measuring devices for trailer/vehicle speed and distance tranvelled, are brought along. The method is characterized in that during motion there are simultaneously emitted ultrasound waves down toward the surface of the traffic area from a number N>2 of ultrasound transducers being located in a row on the underside of and along a straight bar which is arranged substantially parallel to the road surface on the trailer/vehicle and in a longitudinal direction. The ultrasound transducers are mounted an equal distance x between every two successive transducers, and each transducer receives an ultrasound echo from the surface which is due to that transducer's own emission.
Preferably the method is also characterized in that the measurements are constantly repeated during motion in such a manner that a new ultrasound wave emission is made when the trailer/vehicle has advanced a distance nx in relation to the preceding measurement, n being an integer and n<N-1, so that an overlap with the preceding measurement is achieved.
According to another favourable feature of the present invention, the successive measurements made during motion are chained together after their recording by means of a pre-programmed computer to create a continuous elevation profile of the longitudinal dimension of the traffic area.
Preferably the ultrasound transducers are also tested for correct functioning by means of an automatically controlled comparison of measurement results at corresponding positions by overlap measurements.
The invention also relates to an apparatus for measuring surface roughness along the longitudinal dimension of the traffic area adapted to be placed in the vehicle/trailer, and comprising control means, energizing means and recording means for the measurements, as well as measuring devices for the trailer/v
REFERENCES:
patent: 4048849 (1977-09-01), Gocho et al.
Veidirektoratet, Veglaboratoriet
Woodiel Donald O.
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