Vehicle speed monitoring device based on piezoelectric film sensor

Abstract

The utility model provides a vehicle speed monitoring device based on a piezoelectric film sensor, which comprises at least two accommodating grooves arranged on a driving road at a preset interval, a protective layer, a piezoelectric film sensor, a fixing piece and a filling layer are sequentially arranged in each accommodating groove, one end of each accommodating groove is a sealed end, and the other end of each accommodating groove is a sealed end. The other end of the containing groove is an open end, each piezoelectric film sensor is connected with a signal line, and the end, opposite to the piezoelectric film sensor, of each signal line penetrates through the open end and is connected with a dynamic acquisition instrument. The dynamic acquisition instrument is used for calculating the speed change of the vehicle according to the time difference of electric signals generated when a front axle and / or a rear axle of the vehicle sequentially presses the two piezoelectric film sensors, and accurate speed monitoring and driving state judgment can be conducted through the time difference of the front axle and the rear axle of the vehicle passing through the front piezoelectric film sensor and the rear piezoelectric film sensor. Therefore, important data support is provided for traffic management and safety monitoring.

Description

Technical Field

[0001] This utility model relates to the field of vehicle monitoring technology, and in particular to a vehicle speed monitoring device based on a piezoelectric thin film sensor. Background Technology

[0002] Dynamic Weight-in-Motion System (WIM) is a key technology in various fields such as traffic management, road safety monitoring, and logistics transportation. It allows vehicles to pass through weighing sensors installed on the road surface at normal speeds, enabling the measurement of the vehicle's total weight and the weight of each axle without stopping or significantly slowing down. Traditional WIM systems have already effectively provided vehicle weight information, greatly promoting the development of various application scenarios such as overload enforcement, bridge health monitoring, logistics efficiency improvement, and toll station passage.

[0003] However, while existing traditional WIM systems can accurately measure vehicle weight under normal driving conditions, their functionality still has certain limitations. Specifically, these systems typically only provide vehicle speed data under static conditions, lacking the ability to effectively monitor dynamic vehicle behavior—such as changes in acceleration and deceleration. This means that current WIM systems cannot comprehensively capture the vehicle's motion state throughout the entire passage process, thus limiting their potential in a wider range of applications, such as assessing vehicle driving safety and optimizing traffic flow control. Utility Model Content

[0004] Therefore, the purpose of this invention is to provide a vehicle speed monitoring device based on a piezoelectric thin film sensor to solve the problems mentioned above in the background.

[0005] A vehicle speed monitoring device based on a piezoelectric thin film sensor includes at least two receiving slots spaced at a preset interval on a driving road. Each receiving slot contains, in sequence, a protective layer, a piezoelectric thin film sensor, a fixing element, and a filling layer. One end of each receiving slot is a sealed end, and the other end is an open end. Each piezoelectric thin film sensor is connected to a signal line. The end of the signal line facing away from the piezoelectric thin film sensor passes through the open end and is connected to a dynamic acquisition device. The dynamic acquisition device is used to calculate the vehicle speed change based on the time difference of the electrical signals generated when the front axle and / or rear axle of the vehicle presses onto the two piezoelectric thin film sensors.

[0006] Compared to existing technologies, the advantages of this application are as follows: by using two receiving slots spaced at a predetermined interval on the driving road, the spacing between the two piezoelectric thin-film sensors installed in these receiving slots is ensured to be fixed. This fixed spacing design allows us to use the time difference between the front and rear axles passing through the two piezoelectric thin-film sensors for accurate speed monitoring and driving status judgment. Specifically, when the vehicle is traveling at a constant speed, the time difference recorded by the front axle through the two piezoelectric thin-film sensors (denoted as ΔT1) is equal to the time difference recorded by the rear axle through the same sensors (denoted as ΔT2). However, when the vehicle is accelerating, due to the increased speed, the time difference ΔT1 between the front axle and the two sensors will be greater than the time difference ΔT2 between the rear axle; conversely, if the vehicle is decelerating, the time difference ΔT1 between the front axle and the rear axle will be less than the time difference ΔT2 between the rear axle and the front axle.

[0007] By comparing these two time differences, we can accurately determine whether the vehicle is accelerating, decelerating, or maintaining a constant speed. This method not only provides a specific numerical value of the vehicle's speed but also clearly distinguishes the vehicle's acceleration and deceleration states, thus providing crucial data support for traffic management and safety monitoring. Therefore, this vehicle speed monitoring device based on a piezoelectric thin-film sensor not only possesses high-precision speed measurement capabilities but also effectively identifies dynamic changes in the vehicle, contributing to a more intelligent and efficient traffic management solution.

[0008] Furthermore, the fastener includes a horizontal plate, with vertical plates bent upwards at both ends of the horizontal plate, and a connecting plate bent away from the horizontal plate at one end of the vertical plate, with a through hole for engaging with a bolt.

[0009] Furthermore, the depth of the receiving groove is 20-50mm, the width of the receiving groove is 17-20mm, and the width of the receiving groove is greater than the width of the piezoelectric thin film sensor.

[0010] Furthermore, a rubber ring is provided inside the opening end, and the rubber ring is adapted to the signal line to prevent moisture from entering the receiving groove.

[0011] Furthermore, a coil sensor is provided between two adjacent receiving slots. The coil sensor is used to provide additional timestamp information of the vehicle, thereby helping to improve the accuracy of speed measurement.

[0012] Furthermore, the length and width of the coil sensor are 1.8-2.2m, and the length between two adjacent receiving slots is 2.8-3.2m.

[0013] Furthermore, a waterproof layer is provided on the filling layer, which is made of asphalt or rubber sheet, the filling layer is made of cured concrete, and the protective layer is made of elastic material.

[0014] Furthermore, it also includes a communication module for transmitting the data acquired by the dynamic acquisition device to a remote server. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the vehicle speed monitoring device based on a piezoelectric thin film sensor according to this utility model;

[0016] Figure 2 This is a side view of the vehicle speed monitoring device based on a piezoelectric thin film sensor according to this utility model;

[0017] Figure 3 This is a schematic diagram of the module connection of this utility model;

[0018] Figure 4 The waveform diagram of the piezoelectric thin film sensor signal output obtained by the dynamic acquisition instrument of this utility model;

[0019] Figure 5 This is a side view of the fastener of this utility model.

[0020] Key component symbols: 100, Lane; 10, Receiving groove; 11, Sealing end; 12, Open end; 13, Rubber ring; 20, Protective layer; 30, Piezoelectric thin sensor; 31, Signal line; 32, Dynamic acquisition instrument; 33, Communication module; 40, Fixing component; 41, Horizontal plate; 42, Vertical plate; 43, Connecting plate; 44, Bolt; 50, Filling layer; 60, Waterproof layer; 70, Coil sensor. Detailed Implementation

[0021] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.

[0022] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] Please see Figures 1 to 3 The image shows a fixing device for an emergency monitoring and early warning device according to an embodiment of the present invention. It includes at least two receiving slots 10 opened at a preset interval on the road. Each receiving slot 10 is provided with a protective layer 20, a piezoelectric thin film sensor 30, a fixing member 40 and a filling layer 50 in sequence. One end of the receiving slot 10 is a sealed end 11 and the other end of the receiving slot 10 is an open end 12. Each piezoelectric thin film sensor is connected to a signal line 31. The end of the signal line 31 facing away from the piezoelectric thin film sensor passes through the open end 12 and is connected to a dynamic acquisition device 32. The dynamic acquisition device 32 is used to calculate the speed change of the vehicle based on the time difference of the electrical signals generated when the front axle and / or rear axle of the vehicle presses on the two piezoelectric thin film sensors.

[0025] Please see Figure 4 In the figure, △T1=t3-t1, △T2=t4-t2.

[0026] It is worth noting that by using two receiving slots 10 spaced at preset intervals on the driving road, the spacing between the two piezoelectric thin-film sensors installed within these slots 10 is ensured to be fixed. This fixed spacing design allows for precise speed monitoring and driving status judgment using the time difference between the front and rear axles passing through the two piezoelectric thin-film sensors. Specifically, when the vehicle is traveling at a constant speed, the time difference recorded by the front axle through the two piezoelectric thin-film sensors (denoted as ΔT1) is equal to the time difference recorded by the rear axle through the same sensors (denoted as ΔT2). However, when the vehicle is accelerating, due to the increased speed, the time difference ΔT1 between the front axle and the two sensors will be greater than the time difference ΔT2 between the rear axle; conversely, if the vehicle is decelerating, the time difference ΔT1 between the front axle and the rear axle will be less than the time difference ΔT2 between the rear axle and the front axle.

[0027] By comparing these two time differences, we can accurately determine whether the vehicle is accelerating, decelerating, or maintaining a constant speed. This method not only provides a specific numerical value of the vehicle's speed but also clearly distinguishes the vehicle's acceleration and deceleration states, thus providing crucial data support for traffic management and safety monitoring. Therefore, this vehicle speed monitoring device based on a piezoelectric thin-film sensor not only possesses high-precision speed measurement capabilities but also effectively identifies dynamic changes in the vehicle, contributing to a more intelligent and efficient traffic management solution.

[0028] Please see Figure 5 Furthermore, in order to stably limit the piezoelectric thin sensor 30 within the receiving groove 10, the fixing member 40 includes a horizontal plate 41, with vertical plates 42 bent upwards at both ends of the horizontal plate 41. A connecting plate 43 is bent away from the horizontal plate 41 at one end of the vertical plate 42. A through hole is provided on the connecting plate 43 to cooperate with the bolt 44. By passing the bolt 44 (expansion bolt 44) through the through hole and then into the preset hole of the lane 100, the fixing member 40 is fixed within the receiving groove 10, thereby stably limiting the piezoelectric thin sensor 30 within the receiving groove 10.

[0029] Specifically, the depth of the receiving groove 10 is 20-50mm, the width of the receiving groove 10 is 17-20mm, and the width of the receiving groove 10 is greater than the width of the piezoelectric thin film sensor, so as to provide sufficient space for installing each layer of components and to ensure that the sensor is not affected by external pressure when it is working.

[0030] Specifically, a rubber ring 13 is provided inside the opening end 12. The rubber ring 13 is adapted to the signal line 31 to prevent moisture from entering the receiving groove 10 and to ensure the long-term reliability of the system.

[0031] Furthermore, a coil sensor 70 is provided between two adjacent receiving slots 10. The coil sensor 70 is used to provide additional timestamp information of the vehicle, thereby helping to improve the speed measurement accuracy.

[0032] Specifically, the length and width of the coil sensor 70 are 1.8-2.2m, and the length between two adjacent receiving slots 10 is 2.8-3.2m.

[0033] Specifically, a waterproof layer 60 is also provided on the filling layer 50. The waterproof layer 60 is made of asphalt or rubber sheet to further enhance structural stability and waterproof performance.

[0034] The filler layer 50 is made of cured concrete (fast-curing concrete).

[0035] The protective layer 20 is made of an elastic material. The elastic material can be fine sand or foam padding to cushion the impact on the sensor when a vehicle passes by and reduce the influence of external environmental factors.

[0036] Furthermore, it also includes a communication module 33, used to transmit the data acquired by the dynamic acquisition device 32 to a remote server.

[0037] As mentioned above, vehicle speed measurement involves installing two piezoelectric thin-film sensors on the road surface, with a spacing of 3 meters or a fixed length between the sensors. When the vehicle speed varies, the time taken to pass through the fixed-length piezoelectric thin-film sensor differs, calculated using the formula: Vehicle speed = Sensor installation distance L / Time taken to pass through the two sensors. Since the vehicle is a two-axle or multi-axle vehicle, the state is identified by measuring the difference in time taken for different axles to pass through.

[0038] The specific installation steps are as follows:

[0039] 1. Preparations before installation

[0040] Assess site conditions: Select a suitable installation location, ensuring the road surface is flat, dry, and free of obvious cracks or damage. Also consider factors such as traffic flow and vehicle type.

[0041] Determine the installation spacing: Determine the standard spacing (e.g., 3 meters) between the two piezoelectric film sensors according to the design requirements. This will be used for subsequent speed calculations.

[0042] 2. Road surface treatment

[0043] Surface cleaning: Use appropriate tools to thoroughly clean the selected area of ​​the road surface to remove dust, oil, and other impurities to ensure good contact between the sensor and the ground.

[0044] Mark the installation location: Use marking lines or templates to accurately mark the specific installation location of each sensor, ensuring that they span the entire width of the lane and remain parallel.

[0045] 3. Excavate trenches

[0046] 3.1 Planning and Surveying

[0047] Precise Measurement: Use measuring tools (such as laser rangefinders, steel tape measures, etc.) to accurately measure and mark the installation position of each sensor, ensuring that the spacing between them is the design value (e.g., 3 meters) and spans the entire lane width.

[0048] Mark the trench boundaries: Clearly mark the boundaries of the trench to be excavated on the road surface with chalk or spray paint, ensuring that the lines are straight and meet the design requirements.

[0049] 3.2 Cutting the groove

[0050] Cutting equipment selection: Use a professional road cutting machine for cutting operations. This type of machine can provide straight cuts and reduce the impact on the surrounding road structure.

[0051] Cutting depth control: Adjust the cutting machine blade depth to approximately 5-10 cm, depending on local traffic conditions and road material type. For asphalt pavements, a shallower cut is usually sufficient; for concrete pavements, a deeper cut may be necessary.

[0052] Cutting width determination: Determine the groove width based on the actual size of the piezoelectric film sensor. Generally, it should be about 1-2 cm wider than the sensor to facilitate installation and subsequent backfilling operations.

[0053] 3.3 Cleaning the trench

[0054] Remove waste: Carefully remove the cut road debris and place it in a designated location for disposal to avoid environmental pollution.

[0055] Clean the bottom: Use a shovel or other tools to thoroughly clean the bottom of the trench, removing loose stones, soil and other debris, and ensuring the bottom of the trench is flat and clean.

[0056] 3.4 Laying the protective layer

[0057] Material selection: Lay a layer of soft, resilient material, such as fine sand, foam pads, or a specially designed cushioning pad, at the bottom of the trench, approximately 2-3 centimeters thick. This helps absorb the impact force generated when vehicles pass by, protecting the sensors from direct damage.

[0058] Evenly distributed: Ensure that the protective material is evenly distributed throughout the bottom of the trench, without any obvious bumps or depressions.

[0059] 4. Install the sensor

[0060] 4.1 Placement of Sensors

[0061] Inspection of appearance: Before placing the piezoelectric film sensor into the trench, carefully inspect it for any physical damage or defects, such as cracks or wrinkles.

[0062] Accurate positioning: Gently place the sensor on the protective layer inside the trench, ensuring it is fully extended and in close contact with the ground. If the sensor has multiple segments, ensure that each segment is securely connected and free from twisting.

[0063] Keep it level: Use a spirit level to check that the sensor is level. If necessary, fine-tune its position to ensure that it responds evenly to pressure changes as a vehicle passes by.

[0064] 4.2 Fixed Sensor

[0065] Fixing method selection: Choose the appropriate fixing method based on the actual situation. One common method is to apply a small amount of special adhesive to both sides of the sensor and then gently press it to adhere to the bottom of the trench. Another method is to use a custom-made fixing device to secure the sensor, but it is necessary to ensure that no additional stress is applied to the sensor.

[0066] Prevent movement: Ensure the sensor is securely fixed in the trench and will not shift or warp due to vehicle passage.

[0067] 4.3 Connection Lines

[0068] Cabling planning: Plan the route of the outgoing lines in advance to avoid crossing or tangling the lines as much as possible and reduce the possibility of signal interference.

[0069] Waterproofing: For exposed parts, especially joints, use waterproof tape or heat shrink tubing to seal them to prevent moisture intrusion and short circuits.

[0070] Marking the route: To facilitate maintenance and troubleshooting, mark the start and end points of the lead-out lines, as well as the corresponding lane numbers and other information, at appropriate locations.

[0071] 4.4 Check installation quality

[0072] Visual inspection: Visually inspect the sensor and its leads again to ensure that all components are correctly installed and there are no obvious problems.

[0073] Functional testing: Use portable testing instruments to perform preliminary functional tests on the newly installed sensors to verify whether they can work properly and output the expected signals.

[0074] 5. Backfilling and Repair

[0075] Backfill material: Use fast-curing concrete or other high-strength filler materials to fill the trench, ensuring that its surface is flush with the surrounding road surface and does not affect the normal driving of vehicles.

[0076] Compaction treatment: Use tools such as small vibratory compactors to properly compact the backfill area to improve the stability of the overall structure.

[0077] Surface repair: Finally, the installation area is treated with surface treatment, such as applying asphalt or laying rubber sheets, to restore the original road appearance and enhance durability.

[0078] 6. Testing and Calibration

[0079] Preliminary testing: After installation, immediately conduct preliminary functional tests to check whether the sensor can output signals correctly.

[0080] System calibration: Through a series of standard vehicle passage tests, the system parameters are adjusted to ensure that the measurement accuracy meets expectations.

[0081] 7. Maintenance and upkeep

[0082] Regular inspections: Regularly inspect the sensors and their connecting components to promptly identify and resolve potential problems.

[0083] Cleaning and maintenance: Keep the area around the sensor clean to prevent debris from accumulating and affecting detection results.

[0084] This application enables effective identification of vehicle speed and acceleration / deceleration status by fully utilizing the fixed-space installation of existing sensors and their output signal information without adding additional hardware. This approach simplifies the system architecture, reduces costs, and maintains high-precision monitoring capabilities.

[0085] Specifically, vehicle speed calculation relies on the signal amplitude, pulse width, and timing information acquired by the dynamic data acquisition system as the front and rear axles pass the piezoelectric thin-film sensors. Since the mounting distance between the piezoelectric thin-film sensors is known and fixed, vehicle speed can be determined through simple mathematical calculations: vehicle speed equals the sensor mounting distance divided by the time difference (ΔT) between the front axle and the two piezoelectric thin-film sensors. This method not only accurately measures vehicle speed but also determines whether the vehicle is accelerating or decelerating by comparing the time difference between the front and rear axles passing the same sensors.

[0086] For example, when a vehicle is traveling at a constant speed, the time difference between the front and rear axles passing through the two sensors is equal; however, when the vehicle accelerates, the time difference for the front axle becomes greater than that for the rear axle; conversely, during deceleration, the time difference for the front axle is less than that for the rear axle. Through this mechanism, we can not only obtain the vehicle's speed data but also clearly understand its acceleration and deceleration behavior, thus providing valuable information for traffic management and safety monitoring.

[0087] In summary, the fixing device of the emergency monitoring and early warning equipment in the above embodiments of this utility model has the following beneficial effects: by opening two receiving slots at a preset interval on the driving road, the distance between the two piezoelectric thin film sensors set in these receiving slots is ensured to be fixed. This fixed distance design allows us to use the time difference between the front and rear axles passing through the two piezoelectric thin film sensors to perform accurate speed monitoring and driving status judgment. Specifically, when the vehicle is traveling at a constant speed, the time difference recorded by the front axle through the two piezoelectric thin film sensors (denoted as ΔT1) is equal to the time difference of the rear axle through the same sensor (denoted as ΔT2). However, when the vehicle is accelerating, due to the increase in speed, the time difference ΔT1 between the front axle and the two sensors will be greater than the time difference ΔT2 between the rear axle; conversely, if the vehicle is decelerating, the time difference ΔT1 between the front axle and the rear axle will be less than the time difference ΔT2 between the rear axle and the front axle.

[0088] By comparing these two time differences, we can accurately determine whether the vehicle is accelerating, decelerating, or maintaining a constant speed. This method not only provides a specific numerical value of the vehicle's speed but also clearly distinguishes the vehicle's acceleration and deceleration states, thus providing crucial data support for traffic management and safety monitoring. Therefore, this vehicle speed monitoring device based on a piezoelectric thin-film sensor not only possesses high-precision speed measurement capabilities but also effectively identifies dynamic changes in the vehicle, contributing to a more intelligent and efficient traffic management solution.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A vehicle speed monitoring device based on a piezoelectric thin film sensor, characterized by, The application relates to a speed measurement device for vehicles, which comprises at least two accommodating grooves arranged on a driving road at preset intervals, a protective layer, a piezoelectric thin film sensor, a fixing piece and a filling layer are sequentially arranged in each accommodating groove, one end of the accommodating groove is a sealed end, the other end of the accommodating groove is an open end, each piezoelectric thin film sensor is connected with a signal line, one end of the signal line away from the piezoelectric thin film sensor penetrates through the open end and is connected with a dynamic acquisition instrument, and the dynamic acquisition instrument is used for calculating the speed change of a vehicle according to the time difference of electric signals generated by a front axle and / or a rear axle of the vehicle pressing on two piezoelectric thin film sensors in sequence.

2. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1 wherein, The fixing piece comprises a horizontal plate, vertical plates are upwardly bent at two ends of the horizontal plate respectively, a connecting plate is bent away from the horizontal plate at one end of the vertical plate away from the horizontal plate, and a through hole matched with a bolt is formed in the connecting plate.

3. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1 wherein, The depth of the accommodating groove is 20-50 mm, the width of the accommodating groove is 17-20 mm, and the width of the accommodating groove is greater than the width of the piezoelectric thin film sensor.

4. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1, wherein, A rubber ring is arranged in the open end, the rubber ring is matched with the signal line, and water is prevented from entering the interior of the accommodating groove.

5. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1, wherein, A coil sensor is arranged between two adjacent accommodating grooves, the coil sensor is used for providing additional timestamp information of the vehicle, and the speed measurement precision is improved.

6. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 5, wherein, The length and width of the coil sensor are 1.8-2.2 m respectively, and the length between two adjacent accommodating grooves is 2.8-3.2 m.

7. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1 wherein, A waterproof layer is further arranged on the filling layer, the waterproof layer is asphalt or a rubber plate, the filling layer is made of solidified concrete, and the protective layer is made of an elastic material.

8. The piezoelectric thin film sensor based vehicle speed monitoring device as claimed in claim 1, wherein, A communication module is further arranged, which is used for transmitting data acquired by the dynamic acquisition instrument to a remote server.

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