Patent Application
20240151574
The present invention relates to a weigh-in-motion system for motor vehicles based on flexible sensors and fiber-optic. Its field of technical application corresponds to that of systems for measuring dynamic physical events that are caused directly or indirectly by the passage of a motor vehicle over its sensors. The aim of the invention is to monitor road traffic variables such as (but not limited to): detecting vehicles, counting wheels, identifying single and/or double wheelsets, measuring weight per wheel, measuring weight per axle, measuring the weight of groups of axles, measuring the total weight of vehicles and measuring pavement mechanical parameters. The solution proposed by the present invention has a number of advantages, including: a simplified manufacturing process and a compact size, sensors that are immune to electromagnetic interference, a long service life and the possibility of being installed on different types of pavements.
Monitoring traffic parameters is used in the areas of road safety, traffic control, maintenance and infrastructure, diagnosing traffic problems, pricing on toll roads and imposing fines in irregular traffic situations, among many other scenarios. The information generated is used by different agents in society, such as government bodies responsible for the road sector, regulatory agencies, public safety entities, road concessionaires and, in some cases, road users themselves. The constant evolution of road parameter monitoring techniques is relevant and brings benefits to society.
As known technical experts in the field of weigh-in-motion, the movement of a vehicle on the pavement generally causes physical effects which, when monitored, generate information about the vehicle's characteristics. These characteristics are related to the constructive aspects of the vehicle, such as weight, dimensions, number of wheels and axles, among others, and to the use of the vehicle that is moving over the pavement, including speed, acceleration, load, number of passengers, among others. Currently known methodologies for detecting and measuring physical parameters involving vehicle traffic are magnetic detection, image detection, optical sensor detection, radar detection, vibration detection, deformation detection and temperature detection.
In some cases, a road traffic monitoring system uses a combination of two or more of the methodologies described above to generate as much information as possible, or even to reduce the uncertainties intrinsic to a given technology by combining the data captured.
In order to guarantee measurement with low uncertainty of a given variable of interest, the most common technique adopted, whatever the technology applied, is to have as many data readings as possible, so as to have a larger sample and consequently greater precision.
In the case of weighing in motion, both techniques are commonly used: the combination of different sensors (generally inductive loops in combination with piezoelectric sensors or load cells) and the installation of a greater number of sensors when greater precision is desired.
In general, a moving vehicle is weighed by measuring the deformations or vibrations exerted on the road surface. The main differences between measurement methodologies for fiber optic-based sensors, whether reported in the literature in the form of patents or technical articles, relate to the types of sensor elements and their encapsulation. The types of sensor elements vary depending on the type of quantity to be measured, such as intensity, frequency and/or phase, or wavelength of the optical wave. The encapsulation, in turn, consists of the protective element and, above all, the mechanical transduction element responsible for transforming and/or amplifying the force components related to the vehicle's weight.
Some patent registrations in the area of traffic monitoring with fiber optic sensors can be found in patent databases.
In Australian patent WO2001027569A1, the optical fiber is fixed to a substrate, a deflection plate, which deforms as vehicles pass by and the detection of the optical fiber deformation is based on interferometric measurement.
In British patent GB2056672A, the optical fiber is placed next to and across the path where the vehicle passes.
U.S. patent Ser. No. 12/376,875 uses a strain gauge consisting of a fiber optic Fabry Perot interferometer.
European patent EP20110160916 uses a flexible plate with fiber optic diffraction networks to measure weight.
In the U.S. patent Ser. No. 07/410,764 the optical fiber is installed between rigid and semi-rigid plates to measure pressure through the deformation/bending of the plates.
In the U.S. patent Ser. No. 11/425,392 diffraction networks are connected to a mechanical structure.
In the U.S. patent Ser. No. 10/467,075 a sensor is installed on the road with interferometric detection by Rayleigh backscattering.
U.S. Pat. No. 5,260,520 reports the encapsulation of optical fiber by elastomeric material, which is the transduction element. One of the major problems with this type of material is its dependence on temperature, which alters deformation rates. At higher temperatures, such as those found on pavements, the material can saturate before the end of the measurement scale, thus restricting the sensor's operating range.
U.S. Pat. No. 5,260,520 discloses a device for weighing moving vehicles that is supplied by a plurality of elongated fiber optic sensors defined by an optical fiber embedded in an elastomeric material encapsulation and arranged parallel to each other on the road in the path of the moving vehicles. Each fiber-optic sensor is provided with contact media arranged in a grid that can be selectively altered to have adequate sensitivity for each vehicle weight range. Switch systems are used in conjunction with the fiber optic sensors to provide signals indicating vehicle speed, weight distribution, tire position and wheelbase. The use of an N-shaped switch configuration also facilitates the determination of the number of tires on each axle, and the tire tread on the ground. When the switches in this configuration are made up of optical fibers, the extent of light transmission by the fibers in contact with the vehicle's tires is indicative of the vehicle's weight.
Chinese utility model CN200962255 discloses a fiber vehicle detector comprising a light source, fiber optic sensor unit, detector, data acquisition unit and processing unit, wherein the fiber optic sensor unit comprises two Mach-Zehnder interferometric sensors comprising a stainless-steel bar and a lighter plastic sheet of standard shape. The bar can detect the road vibration signal while the sheet acts as a reinforcement under the road surface. The beneficial effects are improved sensitivity and blocking of electromagnetic interference on the detector, with no effect from the environment, and improved signal-to-noise ratio by adding the stainless-steel bar and lighter plastic sheet to interferometric sensors, where one arm of the sensor is always the reference arm and the other is the signal arm. In addition, the reference arm is immobile and corresponds to the protective enclosure, as is the rejection of the common mode of the differential amplifier in the electronic circuit when the stainless-steel bar and the lighter plastic sheet vibrate together.
Romanian patent RO127980 refers to a method for determining the weight of motor vehicles in motion without restricting in any way the traffic of the vehicles to be weighed and to a device that applies the method. The method measures the variation of the optical power transmitted by an optical fiber depending on the variable weight applied, using an opto-electronic device with a single-mode or multiple-mode optical fiber when there is propagated a light radiation with the infrared spectral gamma wave emitted in a continuous wave regime by a laser diode or an LED, the optical fiber is mounted on a mechanical device that ensures its curvature depending on the weight to be measured. The claimed device comprises a source of radiation in the near infrared spectrum that can be a laser diode or an LED, said laser diode or LED emitting the infrared radiation through an optical fiber bent under the weight of the motor vehicle to be weighed, the micro-bending of the fiber caused by the weight causing a change in the transmission of the light emitted through the fiber, proportional to the weight of the vehicle on the asphalt.
Brazilian patent PI0106699 describes a piece of equipment whose main purpose is to provide an automated mechanism for the supervision and inspection of traffic lanes intended for the exclusive use of certain types of vehicles (public transport, official vehicles, etc.). Its function is to identify and record, through digitized images, unauthorized vehicles that are traveling on the exclusive lanes. It is characterized by having vehicle detectors that collect data through sensors, allowing the presence of a vehicle to be identified at a given place and time, as well as its characterization in terms of length parameters and optionally, weight, height, speed and other information concerning the detected vehicle. The data captured by the vehicle detector is transmitted electronically to a local computer. The local computer receives the data from the vehicle detectors, the images from the video cameras, processes them and feeds a database with the information received and processed. The local computer is capable of operating simultaneously with several vehicle detectors and video cameras. The equipment covered by PI0106699 is characterized by using a communication medium that allows data to be exchanged between the local computer and the central processing unit. The means of communication corresponds to any commercially used technology that allows the interconnection of computers, such as common telephone lines, fiber optics, private lines, radio transmission, local or remote computer network connections, among others. The equipment covered by PI0106699 is also characterized by having a central processing unit that carries out the final processing of the information collected on the local computer. The processing center has the capacity to simultaneously process information from several local computers, and its size varies from a single computer to several computers and other accessories in a computer network. The end product of the equipment covered by patent PI0106699 is the processing center's real-time remote supervision of vehicles, automatic identification of vehicles, especially those whose characteristics captured by the vehicle detector do not match the standards allowed for traffic (identification of offending vehicles), generation of information for issuing infraction notices (fines) including the digitized image of the vehicle at the place and time of the occurrence, the registration data of the vehicle with its license plate identified through the image (by manual typing or automatic recognition when using automatic character recognition tools), the issuance of infraction notices, the generation of data and statistical reports for studies of the behavior and use of the monitored region, among other information that can be easily generated by processing and cross-referencing the information obtained.
U.S. Pat. No. 4,560,016 discloses a method and apparatus for measuring the weight of a moving vehicle, where an optical fiber is embedded in a matrix, such as a rubber mat, and a multiplicity of micro-folding fastening devices are distributed along the path of the optical fiber. Thus, as the wheels of a vehicle pass over the mat, the force of the wheels causes the micro-folded fasteners to compress together and attenuate the light that is transmitted through the optical fiber. The light transmitted through the optical fiber from a light source at one end of the fiber is received by a light receiver at the other end of the optical fiber. Then, by measuring the amount of light input and the net amount of light output and calibrating the device, the weight of each axle and the weight of the vehicle above that axle can be measured.
Chinese patent CN2924496 discloses a device for dynamic vehicle axle weighing by optical fiber grating, which comprises a laser source. The output terminal of the laser source is connected to a first end of the fiber coupler, and a third end of the fiber coupler connected to the fiber grating wavelength module, photoelectric conversion module, data acquisition equipment and industrial PC. The hydraulic pressure sensing element consists of the fiber grid pressure sensing head, hydraulic valve assembly and hydraulic hose. The fiber grid pressure sensing head is made of epoxy polyester to hold the fiber on both sides of the sensing grid in a flexible metal shim, and the shim is connected to the hydraulic valve assembly which is communicated with the hydraulic hose.
Chinese patent 206618472 discloses a multi-stage optical fiber grating weighing sensor based on a telescopic rod structure comprising the multiple light source sensing box body structure, optical splitter, optical power meter, demodulation light path and telescopic link. Where the internal structure of the box includes: upper weighing plate, support spring, position control hole, clamp, lever post, cantilever beam, telescopic link. The surface is glued, respectively, and has a fiber grid over the cantilever beam. Weight load causes the cantilever beam to deform, transmitted through the telescopic link, and changes in the demodulation light output energy value allow the weight to be measured by calculation. The design of the sensor is multi-stage, with the addition of load mass and operating conditions respectively entering different levels to be provided with the overload protector. This structure has succeeded in improving the measurement range by guaranteeing the resolution power of the sensor's measurements.
Chinese patent CN208254420 discloses a distributed optical fiber equipment for measuring ground deformation, configured on the optical fiber end, aligned with the fixed anchor plate of a plurality of optical fibers at the bottom of the optical fiber end, the fixed anchor plate of the optical fiber being the reference point, to be equipped with sensing fiber hole and temperature measuring optical fiber hole in the optical fiber fixed anchor plate, so that it moves along with the soil to realize the real-time load measurement through the sensing fiber and the temperature variation so as to realize the temperature compensation correction, the internal deformation that the soil reaches.
The technologies disclosed by the currently existing patents, in relation to the technology of the present patent, have limitations, drawbacks and disadvantages:
In patents WO2001027569A1, EP20110160916, U.S. Ser. No. 07/410,764 and U.S. Ser. No. 11/425,392 the measurement methodologies employ mechanical transducers based on deflection plates to transform the weight force into mechanical deformation of the optical fiber. In general, this type of sensor has large dimensions, is highly intrusive to the pavement, has highly demanding geometry requirements in terms of installation and is also complex to manufacture.
Patents GB2056672A and RO127980 use the measurement of the variation in the luminous intensity of the light that travels through the optical fiber as the measurement method. The intensity variation occurs by throttling the optical fiber by means of a mechanism with the passage of a vehicle over the fiber. This technique is susceptible to fluctuations in the optical source and detection components, as well as cables and connections, and is therefore inaccurate and unusable in metrological systems.
U.S. Ser. No. 10/467,075 discloses the use of a distributed acoustic measurement system for monitoring road parameters. This technique is based on measurements of acoustic emissions from vehicles and the interaction of vehicles with the pavement.
U.S. Pat. No. 5,260,520 reports the encapsulation of the optical fiber by elastomeric material, which is the transduction element. One of the major problems with this type of material is its dependence on temperature, which alters deformation rates. At higher temperatures, such as those found on pavements, the material can saturate before the end of the measurement scale, thus restricting the sensor's operating range.
Patent CN 20096255 uses a mechanical transducer based on a stainless-steel plate and polymer bar to detect vibration. This design is highly complex mechanically, has a high temperature dependence and is large in size and therefore highly intrusive on the pavement.
More recently, the applicant of the present patent filed the Brazilian patent BR 102017017613-4 called “System for monitoring dynamic weighing and speed of vehicles on lanes” which disclosed fiber optic technology in unique mounting configurations with point and quasi-distributed sensors, which allow rapid response, for the measurement of deformation, vibration, temperature and pressure, be encapsulated in order to enhance sensitivity to the variables of interest, employ specific materials and can be installed with advanced configurations of optical networks, They can be encapsulated to enhance sensitivity to the variables of interest, facilitate the installation process and/or protect the sensing optical fiber, use specific materials and can be installed with advanced optical network configurations, with the advantages of lower cost and longer service life compared to others; the sensors can be multiplexed; they have high spatial resolution across the pavement; the manufacturing technology is simple and inexpensive and transferable in terms of associated costs. The patent presented differs from patent BR 102017017613-4 in three main aspects: the use of a continuous sensor rather than a point based quasi-distributed sensor; the physical effect on which the measurement is based is interferometric, rather than time of flight and measurement of wavelength variation; and, finally, it presents a significant evolution in the method of manufacturing and assembling the weight sensor, which reduces costs and increases the yield of the manufacturing batch.
“IN-MOTION WEIGHING SYSTEM FOR MOTOR VEHICLES BASED ON FLEXIBLE SENSORS AND FIBER OPTIC”, the subject of this patent, was developed to overcome the limitations, drawbacks and disadvantages of existing technologies for dynamic weighing, monitoring physical variables on roadways, through a sensor that uses guided optical interferometry for measurement and built in composite material such as carbon fiber, glass or aramid of any weight or weave, to enable measurements of parameters with high precision in a more reliable and simple way, with the advantages of being able to be installed and molded into any pavement, minimally intrusive, low interference, low cost, long service life, multiplexable, and making use of a simple manufacturing technology at a lower cost than that demonstrated in the state of the art.
The sensor in this patent solved the following technical problems:
The following figures are attached for a better understanding of the present patent:
The sensor in this patent also has the following advantages:
According to
As shown in
As shown in
A presence sensor (3), which consists of a presence probe (3-A), of the inductive loop type, but not limited to this, connected to a processor (3-B) which interfaces with the variables provided by a presence trigger (GP) and a speed (V) trigger, as shown in
A temperature sensor (4) consists of a temperature probe (4-A), of the digital or analog thermometer type, but not limited to these, which is connected to a processor (4-B) that interfaces the temperature variable (T), as shown in
An information processing and display equipment (5) connected to the emission and detection equipment (2), presence sensor (3) and temperature sensor (4) and consists of an information processing machine, computer or dedicated system with a processor with a recorded logic program. This machine contains a logic program specially developed for the operation of the system covered by this patent. The program interfaces frequencies, signals emitted by sensors, generating the data and results desired by the inventor.
The computer program is inserted into the information processing and display equipment (5), and its process is as follows (
The set of sensors, weight sensor(s) (1), presence sensor(s) (3) and temperature sensor (4), are installed in the pavement as shown in
The system in this patent works in the following sequence:
Base Manufacture Fb):
Rod Manufacture Fh):
Assembly M) of the weight sensor (1) takes place in the following sequence:
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021004560.4 | Mar 2021 | BR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/BR2022/050073 | 3/7/2022 | WO |
