Method and appartus for converting static in-ground vehicle scales into weigh-in-motion systems
First Claim
1. A method for determining the total weight of a vehicle moving atop a weight scale comprising the steps of:
- A) providing a weight scale of sufficient length that multiple axle sets of a vehicle can be located on said scale simultaneously;
B) determining at a predetermined data rate the velocity of said vehicle at a plurality of discrete points in time beginning at the point in time when a first tire of said vehicle enters said scale until a point in time when a last tire of said vehicle exits said scale;
C) sensing and recording the position of said axle sets at a plurality of locations on said weight sensor within the period of time that said vehicle is on said scale;
D) determining the instantaneous weight of said vehicle at each of said plurality of discrete points in time;
E) summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
F) normalizing by dividing the result of the preceding step by said predetermined data rate; and
G) multiplying the result obtained in the preceding step by a calibration constant to determine vehicle weight.
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Accused Products
Abstract
An apparatus and method for converting in-ground static weighing scales for vehicles to weigh-in-motion systems. The apparatus upon conversion includes the existing in-ground static scale, peripheral switches and an electronic module for automatic computation of the weight. By monitoring the velocity, tire position, axle spacing, and real time output from existing static scales as a vehicle drives over the scales, the system determines when an axle of a vehicle is on the scale at a given time, monitors the combined weight output from any given axle combination on the scale(s) at any given time, and from these measurements automatically computes the weight of each individual axle and gross vehicle weight by an integration, integration approximation, and/or signal averaging technique.
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Citations
27 Claims
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1. A method for determining the total weight of a vehicle moving atop a weight scale comprising the steps of:
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A) providing a weight scale of sufficient length that multiple axle sets of a vehicle can be located on said scale simultaneously;
B) determining at a predetermined data rate the velocity of said vehicle at a plurality of discrete points in time beginning at the point in time when a first tire of said vehicle enters said scale until a point in time when a last tire of said vehicle exits said scale;
C) sensing and recording the position of said axle sets at a plurality of locations on said weight sensor within the period of time that said vehicle is on said scale;
D) determining the instantaneous weight of said vehicle at each of said plurality of discrete points in time;
E) summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
F) normalizing by dividing the result of the preceding step by said predetermined data rate; and
G) multiplying the result obtained in the preceding step by a calibration constant to determine vehicle weight. - View Dependent Claims (2, 3, 4, 5, 25, 26, 27)
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6. A method for determining the weight of a vehicle axle moving atop a weight scale comprising the steps of:
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A) providing a weight scale of sufficient length that multiple axle sets of a vehicle can be located on said scale simultaneously;
B) determining at a predetermined data rate the velocity of said vehicle at a plurality of discrete points in time beginning at the point in time when a tire of an axle of said vehicle enters said scale until a point in time when said tire exits said scale;
C) sensing and recording the position of each axle at a plurality of locations on said weight sensor within the period of time that said vehicle is on said scale;
D) determining the instantaneous weight of the vehicle axles at each of said plurality of discrete points in time;
E) summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
F) normalizing by dividing the result of the preceding step by said predetermined data rate; and
G) multiplying the result obtained in the preceding step by a calibration constant to determine the weight of said vehicle axle. - View Dependent Claims (7, 8, 9, 10)
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11. A method of weighing a vehicle having multiple adjacent axles moving atop a weight scale, comprising the steps of:
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passing more than one axle over said weight scale at a time such that multiple adjacent axles are on said scale for a period of time;
determining at a predetermined data rate the velocity of said vehicle at a plurality of discrete points in time beginning at the point in time when a first tire of said vehicle enters said scale until a point in time when a last tire of said vehicle exits said scale;
determining the instantaneous weight of said vehicle at each of said plurality of discrete points in time;
summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
normalizing by dividing the result of the preceding step by said predetermined data rate; and
multiplying the result obtained in the preceding step by a calibration constant to determine vehicle weight. - View Dependent Claims (12, 13)
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14. A method of weighing a vehicle having at least two axles, comprising the steps of:
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passing a vehicle having at least two axle sets over a weight sensor of sufficient length to accommodate more than one axle set on said weight sensor at a time;
sensing and recording the position of an axle at a plurality of locations on said weight sensor within a period of time;
determining a velocity profile of said vehicle over said period of time by use of said plurality of sensed and recorded axle positions;
determining axle spacing by use of said variable velocity profile and said sensed and recorded positions of said axle;
sensing and recording an instantaneous weight profile of each axle set_over said period of time by use of said weight sensor;
using said axle spacing to determine a time segment within said period of time when only one of said axle sets is known to be on said scale;
for said one axle, determining at a predetermined data rate the velocity of said vehicle at a plurality of discrete points in time during said time segment;
determining the instantaneous weight of said axle set at each of said plurality of discrete points in time;
summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
normalizing by dividing the result of the preceding step by said predetermined data rate;
multiplying the result obtained in the preceding step by a calibration constant to determine the weight of said one axle set; and
for each axle set comprising more than one axle, using redundant weight information of said axle set to calculate an optimum weight of the individual axles comprising said axle set using the least-squares method. - View Dependent Claims (15, 16)
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17. A method for retrofitting a static scale facility into a weigh-in-motion facility, said static scale facility prior to said conversion including a scale configured to provide a variable weight profile of weight versus time in response to a variable weight placed atop said scale over a period of time, said retrofitting process comprising the steps of:
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locating a weight scale being along a vehicle path, said weight scale being of sufficient length to accommodate more than one axle set of a vehicle on said weight scale at a time, and said weight scale configured to provide weight scale data such as used in static scales;
placing a plurality of tire presence sensors in said vehicle path, said tire presence sensors configured to provide tire switch data; and
installing a processor for evaluating said tire switch data and said static scale weight data and providing weight-in-motion calculations by performing the following steps;
1. determining the velocity of a vehicle at each of a plurality of discrete points in time;
2. determining the instantaneous weight of said vehicle at each of said plurality of discrete points in time;
3. summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
4. normalizing by dividing the result of the preceding step by said predetermined data rate; and
5. multiplying the result obtained in the preceding step by a calibration constant to determine vehicle weight. - View Dependent Claims (18)
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19. Apparatus for determining the weight of a moving vehicle comprising:
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a) a scale having a length such that at least two axles of a multiple-axle vehicle can be received thereon at the same time, said scale generating an output corresponding to the weight of a load located thereon;
b) tire position determining means at various locations along the scale length, said tire position determining means generating switch transitions in response to determining the presence of a tire;
c) a means for digitizing said scale output as a function of time;
d) a means for recording said switch transitions as a function of time; and
e) a means for computing vehicle weight by performing the steps of;
1. determining the velocity of a vehicle at each of a plurality of discrete points in time;
2. determining the instantaneous weight of said vehicle at each of said plurality of discrete points in time;
3. summing the products of the determined velocity and the determined instantaneous weight at each of said plurality of discrete points in time;
4. normalizing by dividing the result of the preceding step by said predetermined data rate; and
5. multiplying the result obtained in the preceding step by a calibration constant to determine vehicle weight. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification