Optical fiber sensing network and optical fiber sensing system for monitoring deformation of automobile chassis

Abstract

The invention belongs to the field of automobile bottom deformation monitoring, and particularly discloses an optical fiber sensing network and an optical fiber sensing system for monitoring deformation of an automobile chassis. According to the invention, the main sensing layer optical fiber is axially laid on the chassis, the temperature compensation layer optical fiber is transversely laid on the chassis, decoupling of temperature and strain signals is realized at the cross node of the main sensing layer optical fiber and the temperature compensation layer optical fiber based on the frequency shift difference model, and the signal identification accuracy is effectively improved. The system adopts a single-mode optical fiber and a high-stability frequency sweeping laser source to improve the stability, the spatial resolution and the dynamic response speed of an optical signal, and longitudinal bending, transverse shearing and torsional deformation are identified through a multi-axis strain separation module. An oil-resistant fluororubber sheath is adopted for optical fiber packaging, and a double-channel structure is introduced, so that the system still has good adaptability and long-term operation reliability in complex roads and climate environments.

Description

Technical Field

[0001] The present application relates to the field of automobile bottom deformation monitoring, and more specifically, to a fiber optic sensing network and a fiber optic sensing system for monitoring automobile chassis deformation. Background Art

[0002] Traditional chassis deformation monitoring technology based on electrical sensing involves attaching resistance strain gauges (accuracy ±5με) or placing accelerometers at key points. However, these technologies have significant limitations: First, spatial coverage is insufficient. The effective monitoring range of a single strain gauge is only 2-3 cm². To fully cover the chassis of a mid-size SUV, more than 300 sensors would need to be deployed, exponentially increasing wiring complexity and increasing chassis weight by 300-510 kg. Second, environmental adaptability is poor. Resistance strain gauges are prone to substrate debonding in humid and oily environments (failure probability >18%). Electromagnetic compatibility testing shows that their signal-to-noise ratio degrades to <20 dB under high-frequency interference from motors. Third, real-time performance is a bottleneck. Under the existing CAN bus architecture, the sampling rate of 100 sensor nodes is limited to 1 kHz, making it difficult to capture the millisecond-level deformation transient response at the moment of impact.

[0003] Patent CN113060068A discloses an electric vehicle chassis collision protection and alarm system that uses optical signals acquired by a microbend fiber sensor to detect deformation of the chassis and battery compartment. The microbend fiber sensor comprises a light source for emitting an optical signal; a multimode optical fiber for transmitting the optical signal; and a photoelectric converter connected to the microprocessor for receiving the optical signal transmitted by the multimode optical fiber and converting the received optical signal into an electrical signal. The microbend fiber sensor can be a sleeve-type microbend fiber sensor or a microbend-type microbend fiber sensor. In the case of a microbend-type microbend fiber sensor, based on the mechanism of the disclosed microbend fiber sensor, it also includes a microbend deformer. The microbend deformer houses the light source, multimode optical fiber, and photoelectric converter, and is configured to deform in response to external pressure. The multimode optical fiber is laid flat between the microbend deformers and passes through the center of the tooth-like structure. The microbend deformer generates periodic bends, resulting in variations in the output light intensity. When the microbend fiber sensor is a sleeve-type sensor, polyester fiber is spirally wrapped around the core of the multimode optical fiber, and then the sleeve is used to secure and protect the core. When the sleeve-type microbend fiber sensor is subjected to external pressure, it undergoes periodic deformation. The multimode optical fiber must be laid between the protective plate and the battery compartment of the electric vehicle. During the specific laying process, the multimode optical fiber is laid in a U-shaped spiral pattern or in a concentric circle.

[0004] This patent obtains optical signals through a micro-bend optical fiber sensor. The multi-mode optical fiber in the micro-bend optical fiber sensor is laid between the protective plate and the battery box of the electric vehicle in a U-shaped spiral manner or in a concentric circle manner. Although the multi-mode optical fiber and micro-bend structure are superior to traditional electrical sensors to a certain extent, they still have the following defects and shortcomings: poor optical signal stability, limited resolution and dynamic response, inability to distinguish between temperature and collision signals, and inability to operate reliably in actual roads / climates. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the purpose of this application is to provide a fiber optic sensing network and a fiber optic sensing system for monitoring automobile chassis deformation, aiming to solve the problems of poor optical signal stability, limited resolution and dynamic response, inability to distinguish between temperature and collision signals, and inability to operate reliably in actual roads / climates.

[0006] In a first aspect, the present application provides a fiber optic sensing network for monitoring automobile chassis deformation, comprising: The main sensing layer optical fiber is laid in a U-shape on the chassis longitudinal and cross beam surfaces to monitor the strain caused by temperature and stress in real time. The temperature compensation layer optical fiber is laid in a horizontal U-shaped suspension above any position of the chassis to monitor the strain caused only by temperature in real time; The multi-axial strain separation module is used to distinguish longitudinal bending strain, transverse shear strain and torsional deformation components through the joint solution of axial fiber and transverse fiber cross nodes.

[0007] Preferably, the optical fiber is a single-mode optical fiber, and the outer layer of the optical fiber is encapsulated with an oil-resistant fluororubber sheath.

[0008] Preferably, the optical fiber of the main sensing layer is rigidly bonded to the surface of the chassis using a thermal expansion coefficient matching glue.

[0009] Preferably, the optical fiber sensing network adopts a dual-channel design, with two sets of optical fibers laid in the main sensing layer and the compensation layer respectively. The two independent optical fibers respectively monitor the tensile and compressive strains at the same position, and eliminate temperature drift errors through differential signals.

[0010] Preferably, a single optical fiber achieves 1m×0.5m area coverage, with a spatial resolution of 1cm in the axial direction and 2cm in the lateral direction.

[0011] Preferably, the distance between adjacent optical fibers in the main sensing layer is no more than 3 cm, and the distance between the optical fibers in the temperature compensation layer and the chassis surface is 2-3 mm.

[0012] Preferably, the multi-axis strain separation module performs a joint solution of the fork nodes in the following manner: (1) The axial optical fiber and the transverse optical fiber are arranged in a grid structure, and each intersection is a strain observation point. Each optical fiber sensor records the strain in the one-dimensional projection direction; (2) Obtain two strain values ​​in the axial direction and two strain values ​​in the transverse direction of each cross node through a dual-channel optical fiber sensor; (3) Based on the axial and transverse strain values ​​obtained at the intersection, the overdetermined linear equations are solved to obtain the longitudinal bending strain, transverse shear strain, and torsional deformation components.

[0013] In a second aspect, the present application provides a fiber optic sensing system for automobile chassis deformation monitoring, comprising: the fiber optic sensing network as described in the first aspect, a tunable laser, an optical coupler, a circulator, an optical modulator, and a photoelectric converter; wherein, The tunable laser is used to generate narrow linewidth laser with continuous and linear frequency changes, and output it to the main sensing layer optical fiber and the temperature compensation layer optical fiber; The optical coupler is used to divide the input laser into multiple paths in proportion and output them to the circulator, or to combine the return signal with the reference light; The circulator is used for unidirectional transmission of optical signals: it injects the optical fiber of the main sensing layer from port 1 to port 2, then extracts the backscattered light from port 2 to port 3 and outputs it to the optical modulator; The optical modulator is used to generate calibration pulses through voltage control, compensate for the nonlinear error of the laser frequency sweep, and output the signal to the photoelectric converter; The photoelectric converter is used to convert the light intensity fluctuation of the interference light signal into a current signal.

[0014] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0015] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies: (1) To address the problem of being unable to distinguish between temperature and collision signals, this application proposes a fiber optic sensing network for monitoring automobile chassis deformation. Through a dual-channel design consisting of a main sensing layer fiber (monitoring strain + temperature) and a transverse temperature compensation layer fiber (monitoring only temperature), and establishing a frequency shift differential model at the cross-node, the strain and temperature signal components are decoupled: the first channel reflects the total frequency shift (including the dual effects of strain and temperature), and the second channel reflects only the frequency shift caused by temperature. The difference between the two is used to obtain the true mechanical strain, and then the stress response is calculated using Hooke's law. This method overcomes the interference of factors such as temperature rise, engine thermal radiation, and external environmental temperature changes on the sensing results, allowing collision-induced structural deformation to be clearly distinguished and accurately identified, avoiding false alarms or missed alarms.

[0016] (2) In order to solve the problem of being unable to operate reliably in actual roads / climates, this application proposes a fiber optic sensing network for monitoring the deformation of automobile chassis. By selecting single-mode optical fibers with high mechanical strength and low refractive index drift, and encapsulating them with fluororubber sheath materials that are resistant to oil, corrosion, and UV rays, the system effectively resists the erosion and loss of sensing materials caused by road and climate conditions such as mud, salt spray, extreme cold, and extreme heat. At the same time, the system adopts a passive sensing solution, and the optical fiber body does not require power supply. It has good vibration resistance and anti-electromagnetic interference capabilities, and is suitable for the operating environment of high-voltage and high-frequency components of electric vehicles. In addition, through the dual-channel structure, even if a part of the optical fiber is damaged, the other group of optical fibers can maintain the key area monitoring task, significantly improving the stability and engineering reliability of the system under actual complex operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of laying a fiber optic sensing network for automobile chassis deformation monitoring provided in an embodiment of the present application.

[0018] Figure 2 This is a schematic diagram of the structure of a fiber optic sensing system for automobile chassis deformation monitoring provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0021] This application proposes laying the main sensing layer optical fiber axially and the temperature compensation layer optical fiber transversely on the chassis, and decoupling the data at the intersection to obtain temperature and strain values.

[0022] like Figure 1 As shown, this application proposes a fiber optic sensing network for automobile chassis deformation monitoring, comprising: The main sensing layer optical fiber is laid in a U-shape on the chassis longitudinal and cross beam surfaces to monitor the strain caused by temperature and stress in real time. The temperature compensation layer optical fiber is laid in a horizontal U-shaped suspension above any position of the chassis to monitor the strain caused only by temperature in real time; The multi-axial strain separation module is used to distinguish longitudinal bending strain, transverse shear strain and torsional deformation components through the joint solution of axial fiber and transverse fiber cross nodes.

[0023] Preferably, the optical fiber is a single-mode optical fiber, and the outer layer of the optical fiber is encapsulated with an oil-resistant fluororubber sheath.

[0024] It should be noted that, in order to address the problem of poor stability of optical signals, this application adopts single-mode optical fiber to replace traditional micro-bend structure multi-mode optical fiber as the core transmission medium. The single-mode has strong anti-interference ability and stable signal, which significantly reduces the signal fluctuations caused by inter-modal dispersion and interference; at the same time, the outer layer of the optical fiber is encapsulated with an oil-resistant, high-insulation fluororubber sheath, so that the tensile strength is ≥15MPa, which can effectively prevent the additional attenuation of the optical signal caused by chassis environmental pollution such as moisture, mud, and oil stains; combined with the narrow linewidth, linear continuous frequency sweeping laser source provided by the tunable laser, the consistency and coherence of the signal source are enhanced, and the overall optical signal stability, anti-interference and anti-attenuation capabilities of the system in long-term operation are improved, and the goal of stably obtaining optical response signals in complex environments is achieved.

[0025] Preferably, thermal expansion coefficient matching glue is used to rigidly bond the main sensing layer optical fiber.

[0026] Preferably, the optical fiber sensing network adopts a dual-channel design, with two sets of optical fibers laid in the main sensing layer and the compensation layer respectively. The two independent optical fibers respectively monitor the tensile and compressive strains at the same position, and eliminate temperature drift errors through differential signals.

[0027] It should be noted that even if one set of optical fibers is damaged, the system can still maintain monitoring capabilities through the other set of data, but will lose its strain separation function. To further ensure the normal operation of the separation function, more optical fibers with multiple channels, such as three or four channels, can also be used.

[0028] Preferably, a single optical fiber can achieve 1m×0.5m area coverage with a spatial resolution of 1cm (axial)×2cm (lateral), thus realizing fully distributed monitoring and reducing the hardware cost by 83% compared with traditional point sensors.

[0029] It should be noted that in order to address the problems of limited resolution and dynamic response, this application achieves 1m×0.5m area coverage with a single optical fiber by constructing a high-density sensing network of U-shaped axial laying + lateral suspended laying, with a spatial resolution of 1cm in the axial direction and 2cm in the lateral direction, which is two orders of magnitude higher than the coverage density of the patent CN113060068A solution; at the same time, combined with a tunable laser source with a sweep bandwidth of up to hundreds of GHz and a high-speed photoelectric demodulation system, the system's dynamic response rate is increased to the sub-millisecond level, which can effectively capture millisecond-level deformation changes during the impact process, thereby meeting the real-time and continuous monitoring needs in scenarios of high-speed collision or violent shaking of automobiles, and breaking through the bottleneck of traditional strain gauges limited by CAN bus and sampling rate.

[0030] Preferably, the distance between adjacent optical fibers in the main sensing layer is no more than 3 cm, and the distance between the optical fibers in the temperature compensation layer and the surface is 2-3 mm.

[0031] Preferably, the multi-axis strain separation module performs a joint solution of the fork nodes in the following manner: (1) The axial optical fiber and the transverse optical fiber are arranged in a grid structure, and each intersection is a strain observation point. Each optical fiber sensor records the strain in the one-dimensional projection direction; (2) Obtain the axial strain value of each cross node through the dual-channel optical fiber sensor 、 and the strain value in the transverse direction 、 ; (3) Based on the axial and transverse strain values ​​obtained at the intersection, the overdetermined linear equations are solved to obtain the longitudinal bending strain, transverse shear strain, and torsional deformation components.

[0032]

[0033] in, is the longitudinal bending strain; is the transverse shear strain; is the torsional deformation component; The angle between the fiber optic cable and the main axis.

[0034] like Figure 2 As shown, this application proposes a fiber optic sensing system for monitoring automotive chassis deformation, comprising: the aforementioned fiber optic sensing network, a tunable laser, an optical coupler, a circulator, an optical modulator, and a photoelectric converter. The tunable laser is used to generate narrow-linewidth laser light with a continuously linear frequency variation, which is output to the main sensing layer and the compensation layer. Its frequency sweep range can reach hundreds of GHz (for example, a wavelength from 1520nm to 1570nm), and the spatial resolution is inversely proportional to the laser sweep bandwidth. Specifically, the resolution is equal to the speed of light divided by (twice the fiber refractive index multiplied by the sweep bandwidth). The larger the sweep bandwidth, the higher the resolution.

[0035] The optical coupler is used to proportionally split the input laser into multiple paths (for example, 90% for the main sensing path and 10% for the auxiliary calibration path) and output them to the circulator, or to combine the return signal with reference light. Its core function is to ensure a light splitting / combining efficiency exceeding 95%, minimizing signal loss, based on the principle of optical evanescent field coupling.

[0036] The circulator is designed for unidirectional optical signal transmission: from port 1 to port 2 (for injection into the sensing fiber), then from port 2 to port 3 (for backscattered light), and finally output to the optical modulator. Its isolation is superior: the reverse optical signal is attenuated by over 40 decibels (equivalent to a 10,000-fold attenuation), preventing interference from reflected noise. Insertion loss is less than 1 decibel in the forward direction (i.e., signal strength is retained at least 80%).

[0037] The optical modulator generates calibration pulses through voltage control, compensating for nonlinear errors in the laser frequency sweep, and outputs the signal to the optoelectronic converter. A high-frequency phase carrier is added to the lightwave to improve the demodulated signal-to-noise ratio. The lightwave frequency is offset (e.g., by +80 MHz) to separate the signal and noise spectra.

[0038] The photoelectric converter is used to convert the light intensity fluctuation of the interference light signal into a current signal. The interference light intensity presents cosine fluctuation over time, and its fluctuation frequency is proportional to the optical path difference and the frequency sweep speed.

[0039] In the circulator, port 1 is mainly used for the input of optical signals and has an isolation effect on the reverse optical signal; port 2 can be used as both an input port and an output port, has a bidirectional transmission function, and has an isolation effect on the reverse optical signal; port 3 is mainly used for the output of optical signals and has an isolation effect on the reverse optical signal.

[0040] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0041] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0042] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0043] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0044] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0045] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0046] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A fiber optic sensing network for monitoring automobile chassis deformation, characterized in that: include: The main sensing layer optical fiber is laid in a U-shape on the surface of the chassis longitudinal beams and cross beams to monitor the strain caused by temperature and stress in real time; The temperature compensation layer optical fiber is laid in a horizontal U-shaped suspension above any position of the chassis to monitor the strain caused only by temperature in real time; The multi-axial strain separation module is used to distinguish longitudinal bending strain, transverse shear strain and torsional deformation components through the joint solution of axial fiber and transverse fiber cross nodes.

2. The optical fiber sensor network according to claim 1, wherein: The optical fiber is a single-mode optical fiber, and the outer layer of the optical fiber is encapsulated with an oil-resistant fluororubber sheath.

3. The optical fiber sensor network according to claim 1, wherein: The optical fiber of the main sensing layer is rigidly bonded to the chassis surface using thermal expansion coefficient matching glue.

4. The optical fiber sensor network according to claim 1, wherein: The optical fiber sensing network adopts a dual-channel design, with two sets of optical fibers laid in the main sensing layer and the compensation layer respectively. The two independent optical fibers monitor the tensile and compressive strains at the same position respectively, and eliminate temperature drift errors through differential signals.

5. The optical fiber sensor network according to claim 1, wherein: A single optical fiber can achieve 1m×0.5m area coverage, with a spatial resolution of 1cm in the axial direction and 2cm in the lateral direction.

6. The optical fiber sensor network according to claim 1, wherein: The distance between adjacent optical fibers in the main sensing layer is no more than 3 cm, and the optical fiber in the temperature compensation layer is 2-3 mm away from the chassis surface.

7. The optical fiber sensor network according to claim 4, wherein: The multi-axis strain separation module performs a joint solution of the fork nodes in the following way: (1) The axial optical fiber and the transverse optical fiber are arranged in a grid structure, and each intersection is a strain observation point. Each optical fiber sensor records the strain in the one-dimensional projection direction; (2) Obtain two strain values ​​in the axial direction and two strain values ​​in the transverse direction of each cross node through a dual-channel optical fiber sensor; (3) Based on the axial and transverse strain values ​​obtained at the intersection, the overdetermined linear equations are solved to obtain the longitudinal bending strain, transverse shear strain, and torsional deformation components.

8. A fiber optic sensing system for automobile chassis deformation monitoring, characterized in that: include: The optical fiber sensor network, tunable laser, optical coupler, circulator, optical modulator and photoelectric converter according to any one of claims 1 to 7; wherein, The tunable laser is used to generate narrow linewidth laser with continuous and linear frequency changes, and output it to the main sensing layer optical fiber and the temperature compensation layer optical fiber; The optical coupler is used to divide the input laser into multiple paths in proportion and output them to the circulator, or to combine the return signal with the reference light; The circulator is used for unidirectional transmission of optical signals: it injects the optical fiber of the main sensing layer from port 1 to port 2, then extracts the backscattered light from port 2 to port 3 and outputs it to the optical modulator; The optical modulator is used to generate calibration pulses through voltage control, compensate for the nonlinear error of the laser frequency sweep, and output the signal to the photoelectric converter; The photoelectric converter is used to convert the light intensity fluctuation of the interference light signal into a current signal.

Images