Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
1998-08-26
2003-04-29
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S043000, C702S175000, C177S2100EM
Reexamination Certificate
active
06556927
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to devices and methods for highway and traffic engineering data acquisition, including vehicle weighing, vehicle classification, structural analysis, and roadway structural condition monitoring.
2. Background Information
There has long been a need to use electronic sensing in relation to vehicle travel, and obtaining other highway and traffic data for engineering purposes. Current proprietary engineering data acquisition systems for use at permanent roadway sites have been shown to be expensive to install, of limited durability, and for the most part are not interchangeable between the various manufacturers. Current systems require that a large slot be cut into the pavement, and in many cases, that the transducer system be epoxied flush with the surface of the roadway structure. This requires a large expenditure of resources for a relatively short-lived system.
Due to roadway rutting and point impact loading from studded vehicle tires, the durability of these engineering data acquisition systems has been shown to be on the order of two to three years before failure. Many are inherently open loop gain systems, and are subject to an immediate change in calibration. Each axle event has been shown to make a slight change in the characteristics of their transducers. This drift has been demonstrated to be cumulative.
Devices have been patented for obtaining a weight for vehicles while they are in motion. Devices also exist for detecting the presence of a vehicle, in order to activate a traffic signal. Devices also exist for determining the velocity of a vehicle traveling over a certain stretch of road. What these systems lack is the ability to identify a vehicle by the pattern of force which is transmitted by the mass of the vehicle into the roadway structure as the vehicle travels. These prior art systems also lack the ability to analyze the force distribution a vehicle presents to the roadway structure in order to evaluate the loading of each axle of the vehicle, the velocity of a vehicle, and the acceleration and deceleration of a vehicle. These prior art systems also lack the ability to monitor a section of roadway to evaluate the structural condition of the roadway itself. The prior art devices also lack the ability to monitor force distribution from objects and events other than vehicles, such as the force patterns made over road surfaces by avalanches, mud slides, rock falls and even the passage of bicycles, pedestrians and animals. The prior art devices also lack the ability to utilize force distribution from objects and events to track objects and events from one location to another.
Accordingly, it is an object of the invention to provide an apparatus and method for determining the mass, velocity, presence, the acceleration and deceleration, and the tracking of a vehicle over a roadway.
Another object of the invention is to provide an apparatus and method of identifying a vehicle by the force pattern distribution it creates as it passes over a roadway.
A further object of the invention is to provide an apparatus and method for monitoring the physical integrity and condition of a section of roadway structure.
Another object is to provide an apparatus and method for evaluating the distribution of the mass on the axles of a vehicle in motion.
A further object of the invention is to provide an apparatus and a method for detecting the passage of bicycles, pedestrians and animals across a road surface.
A further object of the invention is to provide an apparatus and a method for detecting the presence and severity of such highway maintenance problems as avalanches, mud slides, and rock slides.
Additional objects, advantages and novel features of the invention will be set forth in part in the description as follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
These and other objects are accomplished by a detection system for generating engineering data which senses internal structural picostrains produced by a force event. The picostrains act on an array of one or more transducers, to generate a signal representative of the force event or a signal with information about the force event. The picostrains of interest to the invention include those generated by a vehicle traveling on a roadway or a structure, or another event which generates a force event on a roadway or structure. These picostrains could be sensed by an array of one or more transducers, which generate a signal representative of the force signature of the vehicle or force generator. In one mode of the preferred embodiment of the invention, the applied force from the vehicle creates a three dimensional zone or spheroid of isobaric pressure gradients under each wheel of a vehicle. As a vehicle travels along a road, the wheels of the vehicle apply pressure to the roadway directly below the vehicle. Other objects can create a force event, such as avalanches, rock slides, mud slides, seismic events, pedestrians, animals, bicycles, or motorcycles. The invention can operate in conjunction with a broad array of transducer types, including strain gauges, fiber optic, piezo-electric strip, and cable, accelerometer, capaticitive strip, or any one of many other technologies which may be made to respond to isobaric pressure gradients and horizontal shear.
One version of the invention includes an array of one or more transducers laid horizontally across a roadbed, which sends a filtered and amplified signal to a computer which generates a unique signature for that vehicle, which was the source of the force event. This system can be described in terms of an orthogonal axis system, in which the roadway is the X axis, and the Y axis is horizontal and is perpendicular to the X axis. The Z axis is vertical, and perpendicular to the plane which contains the X and Y axis. The transducer array is laid in slots in the roadway structure, along the Y axis of the roadway. The slots with the transducer array installed are filled with a material such as epoxy which has a modulus of elasticity which makes the slot with the transducer installed behave as an integral part of the roadway structure.
The force which is applied to the roadway structure by a passing vehicle travels along the X axis, and passes over and through the region of the transducer array. The applied force is referenced to a particular time, or T
o
. The applied force is a pressure wave created by an object such as a vehicle traveling on a road. This pressure forms what could be called a virtual spheroid of deformation beneath the applied force. This could be illustrated as a ball with a side compressed from a pressure applied to one side, with the side opposite showing an equivalent compression due to the reactive forces generated within the structural material. The deformation of this virtual spheroid is proportional to:
F
n
approximately=
ks
where F
n
represents the force applied normal to the surface of the spheroid, and where k represents the volumetric force constant of the deformed material, and where s represents the reactive volumetric displacement about the surface of the spheroid. The zone of increased pressure below the wheels of the vehicle is in an isobaric gradient, in an anisotropic structural material, with the highest pressure area closest to the tire, and lower pressure areas radiating out from the tire.
Along with a zone of isobaric pressure with its pressure gradients, the tire of the vehicle can cause a slight physical displacement of the pavement itself. This physical displacement within the pavement structure resembles a wave which proceeds in front of the wheel, and there is also a wave which follows behind the wheel. As the raised wave in the pavement and the
Dykas Frank J.
Idaho Transportation Department
Nipper Stephen M.
Shaver Robert L.
Wachsman Hal
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