Monitoring signal wireless transmission method and system for seat belt online monitoring

Abstract

The present application relates to the technical field of communication, disclose a monitoring signal wireless transmission method and system for seat belt online monitoring, the method comprises: integrating near field magnetic induction transceiver unit in the seat belt lock catch, along the tape cloth support near field magnetic induction and frequency hopping spread spectrum radio frequency dual mode communication distributed relay node;Based on channel quality adaptive switching communication mode, and dynamic selection of optimal frequency hopping frequency point is combined with environmental electromagnetic characteristic database;Local compression encoding is carried out to sensor original signal, and hop by hop transmission to regional convergence gateway, and time stamp calibration, integrity check and redundancy elimination are completed by the gateway, finally uploaded to the central monitoring platform.The system includes seat belt body, miniature near field magnetic induction unit, distributed relay node, regional convergence gateway and central monitoring platform.The system realizes high reliability, low delay, low cost wireless backhaul of seat belt monitoring signal in extreme shielding environment through the above technical scheme.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and specifically relates to a wireless transmission method and system for monitoring signals used in online monitoring of seat belts. Background Technology

[0002] With the rapid development of intelligent transportation systems and vehicle safety monitoring technologies, seat belts, as a core component of occupant restraint systems, require real-time online monitoring to improve driving safety. Existing monitoring solutions typically rely on onboard sensors to collect physical status signals from seat belt buckles or webbing, and then upload the data to a cloud management platform via wireless communication networks to achieve remote monitoring, violation warnings, and post-accident analysis. Such systems place high demands on the reliability, coverage, and power consumption of communication links, especially in complex building structures, underground parking lots, tunnels, and other typical obstructed scenarios where signal penetration loss is high and multipath effects are significant, posing a severe challenge to the stability of wireless transmission.

[0003] Wireless signal transmission technologies for seatbelt online monitoring primarily focus on the integrated application of Low Power Wide Area Networks (LPWAN) and short-range wireless protocols. This approach aims to balance the long battery life requirements of terminal devices with robust connectivity in weak signal environments. Its basic principle is to dynamically select the optimal transmission path under different channel conditions and deployment environments through a multi-mode communication mechanism, thereby ensuring the timely transmission of monitoring data.

[0004] Current mainstream solutions still face structural contradictions: local area networks built on short-range communication technologies such as Wi-Fi or Zigbee have the advantages of low latency and high throughput, but they are easily blocked in densely reinforced concrete areas, resulting in frequent link interruptions and a surge in packet loss rate; while cellular wide-area technologies such as NB-IoT can achieve wide coverage, they have problems such as high communication latency, expensive module costs and dependence on operator tariffs, making it difficult to meet the dual demands of economy and real-time performance in large-scale deployment.

[0005] In existing technologies, some solutions attempt to introduce sub-GHz frequency band communication such as LoRa to enhance penetration capabilities. However, a single LoRa network is prone to channel congestion when high-density nodes are accessed, and lacks an effective anti-interference mechanism. Other studies explore deterministic scheduling under the TSCH (Time Slot Channel Frequency Hopping) architecture, such as the Wi-SUN standard. Although it can improve network reliability, its fixed topology and static routing strategy are difficult to adapt to dynamic link changes caused by vehicle movement or temporary obstruction.

[0006] The aforementioned problems are particularly prominent in seatbelt monitoring, an application scenario highly sensitive to data timeliness and transmission integrity. If critical status signals (such as unfastened seatbelt alarms) are lost or delayed due to network instability, the system's safety protection effectiveness will be directly weakened. Therefore, there is an urgent need for an adaptive hierarchical wireless transmission architecture that integrates the wide-area coverage advantages of LoRa with the reliability of TSCH time-slot frequency hopping, to achieve low-power, high-reliability, and low-cost seatbelt monitoring signal backhaul in complex electromagnetic and physical environments. Summary of the Invention

[0007] This invention provides a wireless transmission method and system for seat belt status monitoring signals, aiming to solve the problems of high link interruption rates and severe data loss caused by multipath fading and penetration loss in environments with strong electromagnetic shielding and multiple physical obstructions, such as complex steel structures and basements. It also avoids the inherent drawbacks of narrowband IoT wide-area communication technologies, such as high communication latency, high module costs, and strong dependence on public cellular network infrastructure. This invention constructs a hybrid low-power local wireless transmission architecture that integrates near-field magnetic induction communication and adaptive frequency hopping spread spectrum mechanisms, achieving high reliability, low latency, and low-cost backhaul of seat belt status monitoring signals in extremely obstructed environments.

[0008] The invention provides a method for wireless transmission of monitoring signals for online seat belt monitoring, comprising:

[0009] A miniature near-field magnetic induction transceiver unit is integrated inside the seat belt buckle mechanism. The miniature near-field magnetic induction transceiver unit operates in the low-frequency band and uses a magnetic field to couple information to penetrate the metal structure.

[0010] Multiple distributed relay nodes are deployed along the seat belt webbing. Each of the distributed relay nodes has a built-in dual-mode communication module that supports dynamic switching between near-field magnetic induction mode and frequency hopping spread spectrum radio frequency mode.

[0011] An adaptive routing mechanism based on real-time channel quality assessment is established. When the signal-to-noise ratio of the near-field magnetic induction link is less than a preset threshold, the frequency hopping spread spectrum radio frequency link is automatically activated, and the frequency sequence with the least interference is selected for data transmission based on the pre-stored environmental electromagnetic characteristics database.

[0012] The raw monitoring signals collected by the seat belt tension sensor, displacement sensor and buckle status switch are locally compressed and encoded to form a fixed-length data frame, which is then transmitted hop-by-hop to the regional aggregation gateway through the hybrid communication link.

[0013] The regional aggregation gateway performs timestamp calibration, integrity verification, and redundancy elimination on the received multi-source monitoring data, generates standardized monitoring messages, and uploads them to the central monitoring platform via wired Ethernet or industrial bus interface.

[0014] Preferably, the integration of a miniature near-field magnetic induction transceiver unit within the seatbelt buckle mechanism includes:

[0015] The miniature near-field magnetic induction transceiver unit includes a loop magnetic core antenna, a power amplifier, a low-noise receiving amplifier, a modem, and a microcontroller.

[0016] The ring core antenna is made of high permeability ferrite material.

[0017] The modem uses binary phase-shift keying modulation.

[0018] The microcontroller periodically detects the received signal strength indicator value. When the value is less than a specified value for three consecutive times, it triggers a communication mode switching command.

[0019] Preferably, the deployment of multiple distributed relay nodes along the seatbelt webbing includes:

[0020] Each of the distributed relay nodes is embedded along the safety belt webbing at intervals of no more than 2 meters, and each relay node includes an independent power management unit, an environmental sensing unit, and a dual-mode communication unit;

[0021] The power management unit consists of a flexible thin-film battery and an energy harvesting circuit. The energy harvesting circuit captures the mechanical energy generated by the vibration of the seat belt through a piezoelectric ceramic sheet and converts it into electrical energy.

[0022] The environmental sensing unit includes a triaxial accelerometer and a magnetic field strength sensor, which are used to identify the motion state and metal occlusion degree of the space where the node is located.

[0023] The frequency hopping spread spectrum radio frequency module in the dual-mode communication unit adopts direct sequence spread spectrum technology, and the frequency hopping pattern is dynamically generated according to a preset pseudo-random sequence.

[0024] Preferably, the establishment of the adaptive routing mechanism based on real-time channel quality assessment includes:

[0025] During the initialization phase, each relay node broadcasts a beacon signal to its neighboring nodes and establishes an adjacency table.

[0026] During normal operation, each node continuously listens to beacon signals from upstream nodes and records the received signal strength indicator, bit error rate, and number of link interruptions.

[0027] When the bit error rate of the near-field magnetic induction link is greater than the specified value or the number of link interruptions reaches 3 times within 1 minute, the node starts the frequency hopping spread spectrum radio frequency link, and excludes the frequency points with a bit error rate greater than the specified value in the past 10 minutes from the pre-stored frequency point sequence library, and selects the frequency point with the highest historical average signal-to-noise ratio among the remaining frequency points as the initial frequency hopping start point.

[0028] During data transmission, if the bit error rate of the current frequency exceeds the threshold for five consecutive data frames, the system will immediately switch to the next frequency until the entire frame of data is reliably transmitted.

[0029] Preferably, the step of locally compressing and encoding the raw monitoring signals collected by the seat belt tension sensor, displacement sensor, and buckle status switch includes:

[0030] The raw monitoring signal is divided into fixed-length time windows, and the data in each window is matched with pre-stored dictionary entries. The dictionary entries include the typical tension value range, displacement change rate range, and buckle opening and closing sequence mode of the seat belt under normal conditions.

[0031] If a match is successful, output the dictionary index and offset; if a match fails, retain the original value and mark it as an abnormal fragment.

[0032] The compressed data frame includes a frame header, node identifier, timestamp, compressed data block, and cyclic redundancy check code.

[0033] Preferably, the regional aggregation gateway performs timestamp calibration, integrity verification, and redundancy elimination on the received multi-source monitoring data, including:

[0034] The regional aggregation gateway is deployed at a weakly shielded location at the edge of the shielded area. It has a built-in multi-channel receiving array that can simultaneously monitor near-field magnetic induction signals and frequency-hopping spread spectrum radio frequency signals from multiple relay nodes.

[0035] The timestamp calibration adopts a two-way time synchronization protocol. The gateway sends a synchronization request to each relay node, the node records the receiving time and returns a response, and the gateway calculates the propagation delay based on the round-trip time and corrects the node's local clock.

[0036] The integrity check is achieved by comparing the cyclic redundancy check code of the data frame with the recalculated check value. If the check fails, a retransmission request is sent to the source node.

[0037] The redundancy elimination is based on a sliding time window mechanism, which deduplicatizes duplicate data frames from the same node within the window, retaining only the first successfully received frame.

[0038] Preferably, the environmental electromagnetic feature database is divided into spatial regions, and each region entry contains a list of high interference frequency points in the historical records of that region and the average attenuation coefficient of the near-field magnetic induction link.

[0039] Preferably, the frequency hopping sequence library contains 16 sets of pseudo-random sequences, the sequence generation algorithm is based on a linear feedback shift register, and the seed value is derived from the node's unique identifier.

[0040] Preferably, the tension sensor is a resistance strain gauge sensor, which is attached to the reinforcing rib on the inner side of the seat belt webbing; the displacement sensor is a non-contact eddy current displacement sensor, which is installed inside the buckle housing; the buckle status detection switch is a Hall effect switch, which is installed between the latch and the lock seat in conjunction with a permanent magnet, and is used to output a binary status signal indicating whether the buckle is closed or open.

[0041] This invention also provides a wireless transmission system for monitoring signals for online seat belt monitoring, comprising:

[0042] The seat belt body integrates a tension sensor, a displacement sensor, and a buckle status detection switch.

[0043] A miniature near-field magnetic induction transceiver unit is embedded inside the seatbelt buckle to collect and initially transmit monitoring signals;

[0044] Multiple distributed relay nodes are deployed along the safety belt webbing. Each relay node includes a dual-mode communication module, an environmental sensing unit, and a power management unit, which are used to adaptively switch between near-field magnetic induction mode and frequency hopping spread spectrum radio frequency mode to relay monitoring signals.

[0045] The regional aggregation gateway is set at the boundary of the shielded area to receive monitoring signals from relay nodes, perform timestamp calibration, integrity verification and redundancy elimination, and output standardized monitoring messages.

[0046] The central monitoring platform is connected to the regional aggregation gateway via a wired interface to receive and parse standardized monitoring messages, enabling real-time monitoring and early warning of seat belt usage status.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. By introducing a near-field magnetic induction communication mechanism, this invention effectively overcomes the shielding effect of metal structures on traditional radio frequency signals, ensuring that a stable initial communication link can still be established in extreme shielding environments such as complex steel structures or basements.

[0049] 2. By deploying distributed relay nodes and endowing them with dual-mode adaptive switching capabilities, a hybrid transmission network with environmental awareness and dynamic reconfiguration characteristics was constructed, thereby improving link robustness.

[0050] By adopting an intelligent frequency hopping strategy based on an environmental electromagnetic characteristic database, continuous interference at fixed frequency points in specific scenarios is avoided, thereby reducing data retransmission rate and communication latency.

[0051] 3. By combining local data compression and redundancy elimination mechanisms, the data traffic of the air interface is reduced, and the battery life of the node is extended.

[0052] 4. The entire system does not rely on public cellular networks, the hardware cost is much lower than that of narrowband IoT solutions, and the end-to-end transmission delay can be controlled, meeting the timeliness requirements of real-time monitoring of seat belt status. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the overall technical solution architecture of the present invention;

[0054] Figure 2 This is a schematic diagram of the core principle framework of the hybrid low-power local wireless transmission architecture that integrates near-field magnetic induction communication and adaptive frequency hopping spread spectrum mechanism in this invention.

[0055] Figure 3 This is a flowchart illustrating the dual-mode communication and environmental awareness logic of the distributed relay node in this invention.

[0056] Figure 4 This is a logical flowchart of the adaptive routing mechanism based on real-time channel quality assessment in this invention.

[0057] Figure 5 This is a flowchart illustrating the logical flow of local compression encoding of monitoring signals and construction of data frames in this invention.

[0058] Figure 6 This is a schematic diagram of the multi-level interaction relationship and data flow of the regional aggregation gateway in this invention, involving multi-channel reception, timestamp calibration, and redundancy elimination. Detailed Implementation

[0059] Please refer to Figures 1 to 6 This invention provides a wireless transmission method and system for monitoring signals in online seatbelt monitoring. Its core lies in constructing a hybrid low-power local wireless transmission architecture that integrates near-field magnetic induction communication and an adaptive frequency-hopping spread spectrum mechanism. This architecture is specifically designed to address environments with strong electromagnetic shielding and multiple physical obstructions, such as complex steel structures and basements. It aims to solve the problems of high link interruption rates and severe data loss caused by multipath fading and penetration loss in traditional short-range wireless communication technologies such as Wireless Fidelity networks or cellular networks. Simultaneously, it avoids the inherent drawbacks of high communication latency, high module costs, and strong dependence on public cellular network infrastructure in narrowband IoT wide-area communication technologies. The specific embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0060] The wireless transmission method for monitoring signals used in online seat belt monitoring includes the following steps:

[0061] S1 integrates a miniature near-field magnetic induction transceiver unit inside the seat belt buckle mechanism. This unit operates in the low-frequency band and uses a magnetic field instead of an electric field for information coupling to penetrate the metal structure.

[0062] S2, multiple distributed relay nodes are deployed along the seat belt webbing. Each relay node has a built-in dual-mode communication module that supports dynamic switching between near-field magnetic induction mode and frequency hopping spread spectrum radio frequency mode.

[0063] S3. Establish an adaptive routing mechanism based on real-time channel quality assessment. When the signal-to-noise ratio of the near-field magnetic induction link is less than a preset threshold, automatically activate the frequency hopping spread spectrum radio frequency link and select the frequency sequence with the least interference for data transmission based on the pre-stored environmental electromagnetic characteristics database.

[0064] S4, the raw monitoring signals collected by the seat belt tension sensor, displacement sensor and buckle status switch are locally compressed and encoded to form a fixed-length data frame, which is then transmitted hop by hop to the regional aggregation gateway through the hybrid communication link;

[0065] S5, the regional aggregation gateway performs timestamp calibration, integrity verification and redundancy elimination on the received multi-source monitoring data, generates standardized monitoring messages, and uploads them to the central monitoring platform via wired Ethernet or industrial bus interface.

[0066] In step S1, the miniature near-field magnetic induction transceiver unit is fully embedded inside the seatbelt buckle housing, with its physical dimensions strictly limited to fit the buckle's compact space. This unit includes a loop magnetic core antenna, a power amplifier, a low-noise receiver amplifier, a modem, and a microcontroller.

[0067] The loop magnetic core antenna is made of high-permeability ferrite material, with an outer diameter of no more than 30 mm, 5 to 10 turns, and an operating frequency of 13 MHz. This frequency selection balances penetration capability and antenna size constraints, and can maintain an effective magnetic field coupling distance of more than 50 cm in a metallic environment.

[0068] The modem uses binary phase shift keying modulation with a data transmission rate of 9600 bits per second. This rate is sufficient to carry the low-bandwidth information flow required for seat belt status monitoring, while ensuring low power consumption during the modulation and demodulation process.

[0069] The microcontroller periodically detects the received signal strength indicator value with a sampling period of 100 milliseconds. When this value is less than the specified value of -75 dB / mW for three consecutive times, it determines that the current near-field magnetic induction link quality has deteriorated, triggers a communication mode switching command, and starts a backup frequency-hopping spread spectrum radio frequency link. The microcontroller is also responsible for managing the power state, waking up relevant circuits only when data acquisition or communication events are triggered, and entering a deep sleep mode at other times to extend battery life.

[0070] In step S2, the distributed relay nodes are embedded along the safety belt webbing at intervals of no more than 2 meters to ensure that the magnetic field coupling strength of the near-field magnetic induction link between any adjacent nodes meets the minimum receiving sensitivity requirement. Each relay node includes an independent power management unit, an environmental sensing unit, and a dual-mode communication unit.

[0071] The power management unit consists of a flexible thin-film battery and an energy harvesting circuit. The flexible thin-film battery provides basic power supply with a capacity greater than 200 mAh and an operating voltage of 3.7 volts. The energy harvesting circuit captures the mechanical energy generated by the vibration of the seat belt through a piezoelectric ceramic sheet and converts it into electrical energy. The piezoelectric ceramic sheet is attached to the inner reinforcing rib of the webbing, and its resonant frequency matches the spectrum of human motion. The typical output power can reach 10 microwatts, which can extend the overall battery life of the node in frequent use scenarios.

[0072] The environmental sensing unit includes a triaxial accelerometer and a magnetic field strength sensor. The triaxial accelerometer is used to identify the motion state of the node in the space, such as being stationary, walking, or falling, and the sampling frequency is 100 Hz. The magnetic field strength sensor is used to detect the density of the surrounding metal structure, and the output value can reflect the degree of local electromagnetic shielding after calibration.

[0073] The frequency-hopping spread spectrum radio frequency module in the dual-mode communication unit operates in the 470-510 MHz band, which is located in the unlicensed industrial, scientific, and medical band, possessing good penetration and avoiding densely populated areas of mainstream communication equipment. This module employs direct sequence spread spectrum technology with a 127-bit spreading code length and a processing gain of approximately 21 dB, effectively improving its resistance to narrowband interference. The frequency-hopping pattern is dynamically generated based on 16 preset pseudo-random sequences, with a hopping rate of 50 hops per second, ensuring communication continuity through frequency domain diversity even when a single frequency point is subjected to continuous interference.

[0074] In step S3, the adaptive routing mechanism is crucial for ensuring communication reliability in extreme environments. During the initialization phase, each relay node broadcasts a beacon signal to its neighboring nodes. The beacon signal contains the node identifier, location index, and current communication mode status. Based on this, the receiving node establishes an adjacency table, recording the physical addresses and default communication link types of its neighboring nodes.

[0075] During normal operation, each node continuously listens for beacon signals from upstream nodes and records the received signal strength indicator (RSI), bit error rate (BER), and number of link interruptions. The RSI is obtained through an analog detector in the RF front-end, converted from analog to digital, and then sent to the microcontroller. The BER is calculated by comparing the known synchronization word in the received data frame with the actual received value. The number of link interruptions is accumulated from timeout events of consecutive failures to receive a valid beacon signal.

[0076] When the bit error rate (BER) of the near-field magnetic induction link exceeds the specified value of 5% or the number of link interruptions reaches 3 within 1 minute, the node determines that the current link is unreliable and immediately initiates the frequency hopping spread spectrum RF link. During the initiation process, the node excludes frequency points with a BER greater than the specified value of 3% within the past 10 minutes from the pre-stored frequency point sequence library. The remaining frequency points are sorted in descending order according to their historical average signal-to-noise ratio, and the highest one is selected as the initial frequency hopping starting point.

[0077] During data transmission, if the bit error rate at the current frequency exceeds 5% for five consecutive data frames, the system immediately switches to the next frequency, and the frequency hopping sequence is used cyclically until the entire frame of data is reliably transmitted. This mechanism ensures that the optimal communication path is always selected in a dynamically changing electromagnetic environment, avoiding the loss of monitoring signals due to the failure of a single link.

[0078] In step S4, the local compression coding strategy aims to reduce air interface data traffic and lower communication power consumption. The original monitoring signal is synchronously acquired by the tension sensor, displacement sensor, and latch status switch, with a uniform sampling frequency of 20 Hz. The tension sensor outputs an analog voltage signal in the range of 0 to 20 kN, quantized by a 16-bit analog-to-digital converter; the displacement sensor outputs a digital displacement value in the range of 0 to 80 mm, with a resolution of 0.1 mm; the latch status switch outputs a binary signal of high or low level.

[0079] All raw data is first divided into fixed-length time windows of 500 milliseconds, corresponding to 10 sampling points. Data within each window is matched against pre-stored dictionary entries, which include typical tension ranges (e.g., 0 to 5 kN), displacement rate ranges (e.g., less than 5 mm / s), and buckle opening / closing timing patterns (e.g., duration greater than 10 seconds after closure) for seatbelts under normal conditions. Successful matches output a dictionary index and offset; the index occupies 8 bits, and the offset is allocated different bit widths depending on the parameter type. Unsuccessful matches retain the original values ​​and mark them as anomalous segments, which are differentially encoded to reduce redundancy.

[0080] The compressed data frame includes a frame header (16 bits), a node identifier (32 bits), a timestamp (64 bits), compressed data blocks (variable length, maximum 160 bits), and a cyclic redundancy check (CRC) code (16 bits), with a total frame length of less than 256 bytes. This format ensures efficient transmission of critical status information under limited bandwidth, while preserving complete details of abnormal events for subsequent analysis.

[0081] In step S5, the regional aggregation gateway is deployed at a weakly shielded location at the edge of the shielded area, typically near steel structure entrances or basement ventilation shafts, to maximize the reception coverage. The gateway has a built-in multi-channel receiver array that can simultaneously monitor near-field magnetic induction signals and frequency-hopping spread spectrum radio frequency signals from multiple relay nodes.

[0082] The multi-channel receiver array consists of four near-field magnetic induction receiving coils and eight radio frequency receiving channels. The receiving coils are orthogonally arranged to enhance directivity, enabling them to capture magnetic field signals of arbitrary orientation in three-dimensional space. The radio frequency receiving channels cover the entire frequency band from 470 dB to 510 MHz, have automatic gain control, and a dynamic range of no less than 90 dB, ensuring stable reception even in environments with both strong and weak signals.

[0083] The timestamp calibration employs a bidirectional time synchronization protocol: the gateway periodically sends synchronization requests to each relay node, the node records the reception time T1 and returns a response, the gateway records the response reception time T2, calculates the one-way propagation delay based on the round-trip time (T2-T0), and corrects the node's local clock deviation. This mechanism controls the network-wide time synchronization error to within 5 milliseconds.

[0084] The integrity check is achieved by comparing the cyclic redundancy check (CRC) code of the data frame with the recalculated check value. If the check fails, a retransmission request is sent to the source node, with a maximum of 3 retransmissions. The redundancy elimination is based on a sliding time window mechanism with a window length of 1 second. Within the window, duplicate data frames from the same node are deduplicated, retaining only the first successfully received frame, effectively eliminating data redundancy caused by retransmission or broadcast mechanisms.

[0085] Finally, the gateway encapsulates the processed data into standardized monitoring messages and uploads them to the central monitoring platform via an industrial-grade Ethernet controller. The output interface conforms to the International Electrotechnical Commission 61850 standard and supports real-time data subscription and alarm push.

[0086] The wireless transmission system for online monitoring of seat belts includes the seat belt itself, a miniature near-field magnetic induction transceiver unit, multiple distributed relay nodes, a regional aggregation gateway, and a central monitoring platform. The seat belt itself integrates a tension sensor, a displacement sensor, and a buckle status detection switch. The tension sensor is a resistance strain gauge sensor, attached to the reinforcing rib inside the seat belt webbing, with a range of 0 to 20 kN. Its output signal is calibrated by a temperature compensation circuit to eliminate the influence of environmental temperature drift.

[0087] The displacement sensor is a non-contact eddy current displacement sensor, installed inside the latch housing, used to detect the insertion depth of the webbing. The measurement range is 0 to 80 mm, with a resolution of 0.1 mm. The excitation coil and detection coil share the same magnetic core to reduce size. The latch status detection switch is a Hall effect switch, installed between the latch bolt and the latch seat in conjunction with a permanent magnet. When the latch bolt is fully inserted into the latch seat, the permanent magnet approaches the Hall element, outputting a low level to indicate a closed state; conversely, it outputs a high level to indicate an open state.

[0088] The miniature near-field magnetic induction transceiver unit is embedded inside the seatbelt buckle. In addition to the aforementioned hardware components, its microcontroller runs a lightweight communication protocol stack, supporting data fragmentation, acknowledgment, and error retransmission mechanisms. The dual-mode communication modules in the distributed relay nodes share the same microcontroller and storage unit. The microcontroller runs an embedded real-time operating system, scheduling communication tasks and managing power status.

[0089] The storage unit pre-stores an environmental electromagnetic characteristics database, a frequency hopping sequence library, and a compressed dictionary. The environmental electromagnetic characteristics database is divided by spatial region, with each region's entry containing a list of historically high-interference frequencies and the average attenuation coefficient of the near-field magnetic induction link within that region. The database can be remotely updated via a central monitoring platform. The frequency hopping sequence library contains 16 sets of pseudo-random sequences, each covering 40 discrete frequency points within the 470-510 MHz band. The sequence generation algorithm is based on a linear feedback shift register, and the seed value is derived from the node's unique identifier, ensuring that each node's frequency hopping pattern is distinct to reduce co-channel interference. The compressed dictionary is loaded during system initialization and can be dynamically optimized based on long-term operating data, adding frequently occurring normal state patterns.

[0090] In addition to the aforementioned functions, the regional aggregation gateway also has local caching capabilities, allowing it to temporarily store up to 72 hours of monitoring data during uplink interruptions, and then upload it in priority order after the link is restored. The gateway integrates a watchdog timer and a fault self-diagnosis module, which can detect RF front-end faults, clock drift anomalies, and storage unit damage, and output diagnostic information through LED indicator lights or a serial debugging interface.

[0091] After receiving standardized monitoring messages, the central monitoring platform analyzes the status data of each node to build a panoramic view of the seat belt usage status. When a sudden change in tension, abnormal displacement, or unexpected opening of the buckle is detected, an audible and visual alarm is immediately triggered and an event log is recorded. At the same time, it supports historical data backtracking and statistical analysis to provide data support for safety management decisions.

[0092] In summary, this invention provides a complete end-to-end wireless transmission solution for monitoring signals. This solution utilizes near-field magnetic induction communication to penetrate metal shielding, distributed relay nodes for link redundancy, adaptive frequency hopping to avoid interference, local compression to reduce traffic, and gateway-level data purification to improve quality. Without requiring public network support, this solution achieves highly reliable, low-latency, and low-cost backhaul of seatbelt status monitoring signals in highly shielded industrial scenarios. End-to-end transmission latency is controlled within 200 milliseconds, data packet loss rate is less than 1‰, and node battery life can reach more than 2 years, fully meeting the stringent requirements of safety production supervision.

[0093] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for wireless transmission of monitoring signals for online monitoring of seat belts, characterized in that, include: A miniature near-field magnetic induction transceiver unit is integrated inside the seat belt buckle mechanism. The miniature near-field magnetic induction transceiver unit operates in the low-frequency band and uses a magnetic field to couple information to penetrate the metal structure. Multiple distributed relay nodes are deployed along the seat belt webbing. Each of the distributed relay nodes has a built-in dual-mode communication module that supports dynamic switching between near-field magnetic induction mode and frequency hopping spread spectrum radio frequency mode. An adaptive routing mechanism based on real-time channel quality assessment is established. When the signal-to-noise ratio of the near-field magnetic induction link is less than a preset threshold, the frequency hopping spread spectrum radio frequency link is automatically activated, and the frequency sequence with the least interference is selected for data transmission based on the pre-stored environmental electromagnetic characteristics database. The raw monitoring signals collected by the seat belt tension sensor, displacement sensor and buckle status switch are locally compressed and encoded to form a fixed-length data frame, which is then transmitted hop by hop to the regional aggregation gateway through the hybrid communication link. The regional aggregation gateway performs timestamp calibration, integrity verification, and redundancy elimination on the received multi-source monitoring data, generates standardized monitoring messages, and uploads them to the central monitoring platform via wired Ethernet or industrial bus interface.

2. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 1, characterized in that, The integrated miniature near-field magnetic induction transceiver unit within the seatbelt buckle mechanism includes: The miniature near-field magnetic induction transceiver unit includes a loop magnetic core antenna, a power amplifier, a low-noise receiving amplifier, a modem, and a microcontroller. The modem uses binary phase-shift keying modulation. The microcontroller periodically detects the received signal strength indicator value. When the value is less than a specified value for three consecutive times, it triggers a communication mode switching command.

3. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 2, characterized in that, The deployment of multiple distributed relay nodes along the seatbelt webbing includes: Each of the distributed relay nodes is embedded along the safety belt webbing at intervals of no more than 2 meters, and each relay node includes an independent power management unit, an environmental sensing unit, and a dual-mode communication unit; The power management unit consists of a flexible thin-film battery and an energy harvesting circuit. The energy harvesting circuit captures the mechanical energy generated by the vibration of the seat belt through a piezoelectric ceramic sheet and converts it into electrical energy. The environmental sensing unit includes a triaxial accelerometer and a magnetic field strength sensor, which are used to identify the motion state and metal occlusion degree of the space where the node is located. The frequency hopping spread spectrum radio frequency module in the dual-mode communication unit adopts direct sequence spread spectrum technology, and the frequency hopping pattern is dynamically generated according to a preset pseudo-random sequence.

4. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 3, characterized in that, The establishment of an adaptive routing mechanism based on real-time channel quality assessment includes: During the initialization phase, each relay node broadcasts a beacon signal to its neighboring nodes and establishes an adjacency table. During normal operation, each node continuously listens to beacon signals from upstream nodes and records the received signal strength indicator, bit error rate, and number of link interruptions. When the bit error rate of the near-field magnetic induction link is greater than the specified value or the number of link interruptions reaches 3 times within 1 minute, the node starts the frequency hopping spread spectrum radio frequency link, and excludes the frequency points with a bit error rate greater than the specified value in the past 10 minutes from the pre-stored frequency point sequence library, and selects the frequency point with the highest historical average signal-to-noise ratio among the remaining frequency points as the initial frequency hopping start point. During data transmission, if the bit error rate of the current frequency exceeds the threshold for five consecutive data frames, the system will immediately switch to the next frequency until the entire frame of data is reliably transmitted.

5. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 4, characterized in that, The process of locally compressing and encoding the raw monitoring signals collected by the seat belt tension sensor, displacement sensor, and buckle status switch includes: The raw monitoring signal is divided into fixed-length time windows, and the data in each window is matched with pre-stored dictionary entries. The dictionary entries include the typical tension value range, displacement change rate range, and buckle opening and closing sequence mode of the seat belt under normal conditions. If a match is successful, output the dictionary index and offset; if a match fails, retain the original value and mark it as an abnormal fragment. The compressed data frame includes a frame header, node identifier, timestamp, compressed data block, and cyclic redundancy check code.

6. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 5, characterized in that, The regional aggregation gateway performs timestamp calibration, integrity verification, and redundancy elimination on the received multi-source monitoring data, including: The regional aggregation gateway is deployed at a weakly shielded location at the edge of the shielded area. It has a built-in multi-channel receiving array that can simultaneously monitor near-field magnetic induction signals and frequency-hopping spread spectrum radio frequency signals from multiple relay nodes. The timestamp calibration adopts a two-way time synchronization protocol. The gateway sends a synchronization request to each relay node, the node records the receiving time and returns a response, and the gateway calculates the propagation delay based on the round-trip time and corrects the node's local clock. The integrity check is achieved by comparing the cyclic redundancy check code of the data frame with the recalculated check value. If the check fails, a retransmission request is sent to the source node. The redundancy elimination is based on a sliding time window mechanism, which deduplicatizes duplicate data frames from the same node within the window, retaining only the first successfully received frame.

7. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 6, characterized in that, The environmental electromagnetic characteristics database is divided into spatial regions. Each region entry contains a list of high-interference frequency points in the historical records of that region and the average attenuation coefficient of the near-field magnetic induction link.

8. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 7, characterized in that, The frequency hopping sequence library contains 16 sets of pseudo-random sequences. The sequence generation algorithm is based on a linear feedback shift register, and the seed value is derived from the node's unique identifier.

9. The wireless transmission method for monitoring signals for online seat belt monitoring according to claim 8, characterized in that, The tension sensor is a resistance strain gauge sensor, which is attached to the reinforcing rib on the inside of the seat belt webbing; the displacement sensor is a non-contact eddy current displacement sensor, which is installed inside the buckle housing; the buckle status switch is a Hall effect switch, which is installed between the latch and the lock seat with a permanent magnet, and is used to output a binary status signal indicating whether the buckle is closed or open.

10. A wireless transmission system for monitoring signals used in online monitoring of seat belts, characterized in that, include: The seat belt body integrates a tension sensor, a displacement sensor, and a buckle status detection switch. A miniature near-field magnetic induction transceiver unit is embedded inside the seatbelt buckle to collect and initially transmit monitoring signals; Multiple distributed relay nodes are deployed along the safety belt webbing. Each relay node includes a dual-mode communication module, an environmental sensing unit, and a power management unit, which are used to adaptively switch between near-field magnetic induction mode and frequency hopping spread spectrum radio frequency mode to relay monitoring signals. The regional aggregation gateway is set at the boundary of the shielded area to receive monitoring signals from relay nodes, perform timestamp calibration, integrity verification and redundancy elimination, and output standardized monitoring messages. The central monitoring platform is connected to the regional aggregation gateway via a wired interface to receive and parse standardized monitoring messages, enabling real-time monitoring and early warning of seat belt usage status.

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