An intelligent recovery system for a seafloor seismometer based on inertial triggering and multi-modal sensing

Abstract

The application discloses a kind of based on inertial trigger and multimodal perception's seabed seismograph intelligent recovery system, belong to marine geophysical exploration equipment technical field, including: sealed pressure cabin, and the main control unit of pressure cabin, capacitive inertial detection unit, attitude sensor, GPS module, data radio station module, LED flash group, power management module are set in the pressure cabin.The application has the advantages of simple structure, high reliability, low power consumption, high searching efficiency.

Description

Technical Field

[0001] This invention relates to the field of marine geophysical exploration equipment technology, and more specifically to an intelligent recovery system for seabed seismometers based on inertial triggering and multimodal sensing. Background Technology

[0002] Currently, after completing their seabed data acquisition missions, seabed seismometers are primarily recovered using the following methods: 1. Timed Ascent: The instrument automatically releases ballast and ascends at preset times. This method cannot flexibly meet actual operational needs, and if the clock is inaccurate, the instrument may be lost.

[0003] 2. Acoustic beacon positioning: After the instrument surfaces, it relies on its onboard acoustic transponder for ranging and positioning by an acoustic receiver on the mother ship.

[0004] Existing methods have obvious drawbacks: Low positioning accuracy: Acoustic positioning error is usually tens to hundreds of meters, making it like finding a needle in a haystack in a marine environment.

[0005] Highly affected by the environment: Acoustic signals are easily affected by temperature, salinity gradients and sea noise when propagating in seawater, leading to signal instability or even loss.

[0006] Low search efficiency: The mother ship needs to conduct a "carpet search" over a large area, which is time-consuming and labor-intensive, and it is almost impossible to operate at night or when visibility is poor.

[0007] 3. Mechanical Trigger Switch: Some equipment uses mechanical pressure switches to sense when the device is bottoming out and surfacing. However, the high pressure and low temperature environment of the deep sea can easily cause mechanical components to jam or fail, resulting in low reliability.

[0008] The existing solution using pressure switches still has the following problems: (1) Sealing problem: Traditional seabed seismometers often sense the status by installing pressure sensors or mechanical switches through openings in the shell, which damages the overall sealing of the equipment and increases the risk of leakage under the high pressure of the deep sea.

[0009] (2) Single state perception: The pressure sensor can only sense the static water pressure and cannot distinguish dynamic processes such as "uniform sinking", "bottoming impact" and "slow floating", which can easily lead to false triggering or missed triggering.

[0010] The power consumption management method is crude: modules such as pressure switches continue to consume power during the long bottoming-out period, affecting the overall battery life of the device.

[0011] Therefore, how to provide an intelligent recovery system for seabed seismometers based on inertial triggering and multimodal sensing is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0012] In view of this, the present invention provides an intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing, which has the advantages of simple structure, high reliability, low power consumption and high search efficiency, and overcomes the shortcomings of the prior art.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: A smart recovery system for a seafloor seismograph based on inertial triggering and multimodal sensing includes: A sealed pressure chamber, and a main control unit, a capacitive inertial detection unit, an attitude sensor, a GPS module, a data transmission radio module, an LED flash assembly, and a power management module installed inside the pressure chamber; The capacitive inertial detection unit is connected to the main control unit and is used to sense the motion state of the instrument. An attitude sensor, connected to the main control unit, is used to collect three-dimensional attitude data after being woken up; The GPS module is connected to the main control unit and is used to obtain positioning information after the instrument floats to the surface of the water; The data transmission radio module, connected to the main control unit, is used to send data packets containing the positioning information to the outside world; An LED flash assembly, connected to the main control unit, is used to emit light signals at night or in low-visibility environments. The power management module connects to the main control unit, capacitive inertial detection unit, attitude sensor, GPS module, data radio module, and LED flash assembly, and provides energy management.

[0014] Furthermore, the capacitive inertial detection unit includes a fixed lower capacitor plate fixed inside the chamber, and a movable upper capacitor plate suspended above the fixed lower capacitor plate by an elastic element. The movable upper capacitor plate moves relative to the fixed lower capacitor plate as the instrument moves, thereby changing the capacitance value.

[0015] Furthermore, the capacitive inertial detection unit also includes a capacitor-to-digital converter connected to the main control unit, used to convert the real-time capacitance value between the upper plate of the movable capacitor and the lower plate of the fixed capacitor into a digital signal and transmit it to the main control unit.

[0016] Furthermore, the main control unit determines the sinking, bottoming, and floating states of the instrument by detecting changes in the capacitance value, and switches the system's working mode according to different states.

[0017] Furthermore, the main control unit pre-stores a capacitance-displacement linearization estimation model based on first-order Taylor expansion, used to convert the real-time acquired capacitance values ​​into displacement values, as shown in the formula:

[0018] in, This represents the minute displacement of the upper capacitor plate relative to its initial equilibrium position. The initial spacing between the capacitor plates in the initial equilibrium state; This is the current capacitance value measured in real time. This is the reference capacitance value calibrated under the initial equilibrium state.

[0019] Furthermore, the main control unit also pre-stores an inertial acceleration calculation formula based on Hooke's law, used to convert the displacement into an acceleration value. The formula is as follows:

[0020] in, This refers to the inertial acceleration acting on the inertial mass block. The spring constant of the spring connected to the upper electrode plate; The total mass of the upper electrode plate and the inertial mass block connected to it; It is the acceleration due to gravity; This represents the displacement of the tension spring of the capacitor plate in the initial equilibrium state, that is, the elongation of the spring when the upper plate is in equilibrium with the upward spring force and gravity.

[0021] Furthermore, the main control unit also pre-stores an instantaneous velocity estimation formula based on acceleration integral, which is used to estimate the instantaneous sinking or rising velocity of the instrument by performing discrete-time integration on the acceleration value. The formula is as follows:

[0022] in, In time The instantaneous descent velocity of the instrument, estimated at all times; In time The acceleration value calculated from Formula 2 at time 1; The time interval for the MCU to perform sampling and calculation; For the first sampling during MCU The acceleration value obtained from the second sample is calculated using formula two. For the number of samples, .

[0023] Furthermore, it also includes a magnetic switch electrically connected to the main control unit; the magnetic switch is used to close under the attraction of an external magnet, triggering the system to enter a low-power lockout state for transportation and storage.

[0024] Furthermore, it also includes a flexible solar panel mounted on top of the pressure-resistant chamber, and a maximum power point tracking charging controller electrically connected to the solar panel and the power management module, for auxiliary charging of the system when the instrument is on the water surface.

[0025] Furthermore, the capacitive inertial detection unit also includes a locking device, which is an electric telescopic rod electrically connected to the main control unit. When the main control unit determines that the instrument has entered the floating state, it controls the electric telescopic rod to extend and press against the upper electrode of the movable capacitor until it contacts and locks against the lower electrode of the fixed capacitor, while simultaneously turning off the power supply to the capacitive inertial detection unit.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention provides an intelligent recovery system for seabed seismometers based on inertial triggering and multimodal sensing. After the instrument floats to the surface, it can actively emit strong light signals and high-precision GPS coordinate information to guide the mother ship to quickly and accurately locate the equipment, thereby significantly improving the recovery success rate and operational efficiency of seabed seismometers. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 A schematic diagram of the overall structure of the submerged and floating seabed seismograph provided by the present invention; Figure 2 This invention provides a schematic diagram of the process of releasing discarded heavy objects. Figure 3 This is a schematic diagram of the internal structure of the intelligent recovery system for the submerged seabed seismograph provided by the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: Embodiment 1 of this invention discloses an intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing. This system is mounted on a floating seabed seismograph, and its core technical solution is as follows: The overall structure includes a sealed and pressure-resistant titanium cabin, which houses a main control unit [MCU (Microcontroller Unit)], a capacitive inertial detection unit, an attitude sensor, a GPS positioning module, a data transmission radio module, an LED flash assembly, and a power management module. All modules are powered by a unified 18650 battery pack.

[0031] Working principle and process: 1. Sinking and Recording Phase: After entering the water, the instrument begins to sink. The capacitive inertial detection unit monitors changes in capacitance. During this period, the main control unit controls the attitude sensor to collect and record the instrument's three-dimensional attitude data (such as tilt angle and azimuth angle) in real time, and stores the data in non-volatile memory.

[0032] 2. Bottom-up Sleep Phase: Once the capacitive inertial detection unit detects that the device has bottomed out, the main control unit confirms that the instrument has stabilized. Immediately, the main control unit sends a sleep command to the attitude sensor and cuts off its power. It also enters a low-power sleep mode, retaining only the capacitive inertial detection unit for minimal-power periodic monitoring to achieve energy conservation.

[0033] 3. Ascent Activation Phase: When recovery is required, the instrument releases ballast and begins to ascend. As the speed increases, the capacitance value measured by the capacitive inertial detection unit increases, at which point the main control unit is immediately activated.

[0034] 4. Active Positioning and Location Phase: After the main control unit is woken up, the following functions are activated in sequence: Activate the GPS module to obtain the latitude and longitude coordinates of the current location.

[0035] Control the LED flash unit to flash at a set frequency and mode (such as SOS, constant light, strobe) with high intensity to provide visual guidance in dark or murky seawater.

[0036] The control data transmission radio module encodes and modulates the acquired GPS coordinate information according to a preset communication protocol and transmits it outward in a broadcast format.

[0037] Specifically, the capacitive inertial detection unit has an "inertial mass block" suspended by a high-strength spring inside the instrument. The bottom of the mass block is the "movable upper electrode plate of a capacitor", and directly below it is the "fixed lower electrode plate of a capacitor" fixed to the bottom of the device.

[0038] Working principle: Sinking Acceleration: The instrument's speed from the water surface will accelerate from 0 to 1m / s. This process is the accelerated sinking process. The inertial mass block compresses the spring upwards, the distance between the plates increases, and the capacitance value decreases. The main control unit MCU captures this capacitance value to determine that the instrument's current state is sinking.

[0039] Bottom-seat impact: The instrument experiences a huge upward acceleration the instant it bottoms out. Due to inertia, the mass block stretches the spring downward, and its velocity drops from 1 m / s to 0 due to the impulse. The distance between the plates decreases sharply, and the capacitance value shows a "transient spike pulse". The MCU captures this pulse as a precise criterion for "bottoming out".

[0040] Floating: The instrument floats up, generating an upward acceleration from 0 to 1 m / s. The mass block pulls the spring downward relative to the surface, the distance between the plates decreases, and the capacitance increases.

[0041] Water surface: During the surfacing phase, all sensors inside the device are turned on to ensure that the lights flash after surfacing and the data transmission radio can send the received GPS signals.

[0042] Data transmission radio module: It is preferred to use a wireless data transmission module that operates in the 433MHz or 915MHz ISM band, which has a long communication distance and strong anti-interference ability.

[0043] ISM (Industrial, Scientific and Medical) Band: Industrial, scientific and medical frequency band.

[0044] Specifically, dynamic attitude recording and quality assessment based on depth change rate: During the descent phase, the MCU simultaneously records capacitance values ​​(indirectly reflecting acceleration) and data from high-precision MEMS attitude sensors. By analyzing the coupling relationship between "descent velocity" (derived from the integral of acceleration) and "attitude angle change," a "descent attitude trajectory" is constructed. This allows for precise determination of whether the instrument experienced a "soft landing" or a "hard impact." If it is a "hard impact," the system automatically marks it in the data file, indicating potential distortion in that segment of seismic data, providing crucial metadata for subsequent data processing.

[0045] Specifically, in the adaptive hierarchical positioning and localization (LoRa+GPS) part, this invention designs a dynamic, multi-stage positioning logic: Phase 1 (Long-distance guidance): If no instructions are received from the mother ship after 15 minutes of ascent, activate the "low-frequency acoustic beacon" (12kHz) to guide the mother ship to the approximate sea area using its long-distance propagation characteristics.

[0046] Phase Two (Mid-range Visual Guidance): After surfacing for one hour, the "high-brightness blue-green LED array" is activated, flashing in a "three short and one long" SOS mode. By utilizing the penetrability of blue-green light in water and the high sensitivity of the human eye, efficient visual positioning is achieved at night or in turbid water.

[0047] Phase 3 (Precise Short-Range Positioning): After the device surfaces, it immediately transmits the latitude and longitude coordinates with centimeter-level accuracy obtained by the GNSS module via the "LoRa Spread Spectrum Data Transmitter". At the same time, it also broadcasts data packets containing the device ID, battery level, and self-test status in a loop, thereby achieving seamless and efficient searching within a range of several kilometers to several meters.

[0048] Specifically, solar-assisted charging and energy management: The instrument integrates a flexible thin-film solar panel on its top casing and is equipped with a maximum power point tracking (MPPT) charge controller. When the device is floating on the water and it is daytime, the system automatically switches to charging mode to replenish the battery. This ensures the device has sufficient power while awaiting recovery, preventing GPS and data transmission functions from failing due to depletion of power.

[0049] Specifically, this invention is mounted on a submerged and floating seabed seismograph, and the structure of the submerged and floating seabed seismograph is as follows: Figure 1 The deployment sequence of the floating-type seabed seismograph is as follows: First, a ship transports the floating-type seabed seismograph to the deployment point. A crane then moves the seismograph to the sea surface. Next, a release device is used to loosen the rope between the crane and the seismograph. Due to gravity, the seismograph will sink. (During the sinking process, the device provided by this invention calculates the current capacitance value by detecting the voltage across the capacitive inertial detection unit. The change in capacitance value indicates that the instrument is sinking. The device then records the data from the inclinometer inside the device and the current capacitance value, and then uses a formula to calculate the sinking value.) (The sinking velocity is estimated), and after sinking to the seabed, it records seabed seismic activity (when the submersible seismograph settles on the seabed, it experiences an impulse, which acts on the capacitive inertial detection unit, causing a change in capacitance, thus indicating that the submersible seismograph has settled on the seabed; after settling, the device enters a low-power state). When retrieving the submersible seismograph, the ship first arrives at the deployment point and then sends a signal to the submersible seismograph using an acoustic signal device. Upon receiving the signal, the submersible seismograph jettisons its own weight (ballast). The weight jettisoning process is as follows... Figure 2As shown, after discarding the weight, the buoyancy of the buoyancy material on the submerged seabed seismograph is greater than its own weight, causing it to rise. (During the acceleration phase of ascent, the capacitive inertial detection unit in this device will detect changes in capacitance, thus knowing that the instrument is recovering and rising. Then the device will wake up the main control unit (here the main control unit MCU uses an STM32 microcontroller). After the main control unit is woken up, it will enable the GPS module, LED flash group and data transmission radio module, and then collect GPS signals and provide light reminders through LED flashing, and send out the GPS signal through the data transmission radio.)

[0050] Specifically, based on the overall usage scenario described above, this embodiment describes the process of using a computer or other device with data processing or control functions to process data or control other devices: In this invention, the core unit for implementing data processing and control functions is the main control unit MCU, which is an STM32 microcontroller. 1. Power-on phase: After power-on, the main control unit (MCU) will first enable the GPS module, LED flashlight group, and data transmission radio module. Then, it will collect GPS signals and provide light reminders through LED flashing. It will also send out GPS signals through the data transmission radio. At this power-on detection phase, the main function is to check whether the LED lights, GPS data collection, and data transmission radio's GPS signal transmission are normal. The computer receiving software receives the GPS signal sent by the data transmission radio and verifies whether it matches the current location of the device. If they match, the power-on detection phase is successful. If they do not match, maintenance is required.

[0051] 2. Equipment Storage and Transportation Stage: After successful power-on testing, the equipment has an internal magnetic switch. This switch is closed by attaching a magnet to the outside of the instrument. When the main control unit (MCU) detects the closed magnetic switch and maintains this state for 5 seconds, it puts the instrument into a low-power state. In this low-power state, only the MCU and the capacitive inertial detection unit are in sleep mode, and the data transmission radio is also in a low-power state (i.e., external command-triggered wake-up state). All other sensors are powered off. The equipment can then be stored and transported in this state. In other words, the magnetic switch closes under the attraction of the external magnet, triggering the main control unit to power off all modules except the capacitive inertial detection unit and the data transmission radio module. Simultaneously, the main control unit and the data transmission radio module enter a low-power state.

[0052] 3. Deployment and Sinking Phase: After the equipment is transported to the deployment point, it will be installed on the floating seabed seismograph. The deployment personnel will control and activate the main control unit (MCU). The equipment will then be transported to the deployment point along with the floating seabed seismograph. A crane will move it to the sea surface, and then the release device will be used to loosen the rope between the crane and the floating seabed seismograph. Due to gravity, the floating seabed seismograph will sink. When the capacitive inertial detection unit detects the accelerated sinking of the equipment, the main control unit (MCU) will capture this capacitance value to determine that the instrument is currently in a sinking state. Then, the attitude sensor will be activated to record the attitude, and the change in capacitance value in the capacitive inertial detection unit will be recorded. The sinking speed can then be estimated using the recorded capacitance value and the formula below.

[0053] See Figure 3 The invention is encapsulated in a titanium alloy chamber with a diameter of 10cm and a height of 20cm. The chamber is divided into three parts: 1. First part: Transparent part. The transparent part is made of light-transmitting pressure-resistant material. Inside the transparent part is a high-brightness blue-green LED array, which is the LED light strip in the schematic diagram above, a GPS module, and a solar panel. The purpose is to allow the light to flash through the instrument. The GPS module is placed here to better receive satellite positioning signals. The solar panel is placed here because it needs to transmit light for solar charging.

[0054] 2. The second part consists of the main control unit MCU, the data transmission radio circuit board, the attitude sensor, the magnetic switch, the circuit part of the capacitive inertial detection unit, and the battery circuit part. This part is the superposition space of various modules and circuit boards. The main control unit MCU acts as the main controller to control and manage the various modules.

[0055] 3. The capacitor part of the third part of the capacitive inertial detection unit has a flat surface with a snap-hole in the center of the cabin. The snap-hole is for passing wires. The flat surface is suspended by three disc springs, which form the upper electrode of the capacitive sensor. The lower electrode is fixed to the fixing rod at the bottom of the device.

[0056] In addition, the antenna of the data transmission radio is brought out through the external vulcanization of the equipment cabin.

[0057] The above describes the overall structure of the equipment.

[0058] Specifically, the overall work process is as follows: 1. When the device is first manufactured, its state is the same as that of the LED lights floating on the water, GPS data collection, and GPS signal transmission via the data transmission radio. At this time, the device will enter a low-power state after being attracted by the magnetic switch inside the device for more than 5 seconds. The capacitive inertial detection unit is still working (i.e., the upper plate of the capacitor is in an active state, and the capacitive inertial detection circuit is in a power-on detection state). The device is locked at this time, and the MCU microcontroller and data transmission radio are in a low-power state. The device can be stored and moved.

[0059] 2. Deployment and Sinking Acceleration Detection: When the equipment is moved to sea level for stationary deployment, on-site personnel will use a computer connected to the receiver of the data radio to send an unlock command (command AA BF 01 00 00 FE) to the transmitter inside the instrument. Upon receiving the unlock command, the transmitter will wake up the MCU. (During this wake-up process, on-site personnel will send an unlock command via a computer with a host computer interface showing both send and receive commands.) If an unlock command (AA BF 01 00 00 FE) is sent and a response (66 AA BF 01 01 00) is received within 5 seconds, the system will detect the unlock. (FE) This indicates that the device's MCU has been successfully woken up via a command sent from the host computer. If no response is received within 5 seconds, the unlock command will be repeatedly sent every 4 seconds, 3 seconds, 2 seconds, and 1 second until a correct response is received. If no response is received within a 1-second interval, the staff will be alerted that the current device status is incorrect and requires salvage and repair. After being woken up, the device is currently in a stationary deployment state at sea level. At this time, the state of the internal capacitor plates is as follows: the lower plate remains relatively stationary with respect to the device, and the upper plate remains stationary, subjected to two forces: its own weight and the tension of a spring. The spring tension balances the weight of the upper plate (including the inertial mass block), keeping the upper plate stationary at sea level. Then, the device is deployed. After deployment, the device's speed will gradually increase from 0 to 1 m / s. At this time, the state of the internal capacitor plates is as follows: the lower plate remains relatively stationary with respect to the device, and the upper plate needs to gradually increase its speed from 0 to 1 m / s (here, 1 m / s is the theoretical value calculated using buoyancy and gravity). The actual constant velocity is calculated and recorded, and then read from the recovered equipment. The 1 m / s below refers to this; it's just an example here. The instrument as a whole experiences a downward acceleration (which can also be understood as the upper plate remaining stationary due to inertia, causing the spring tension to decrease). Therefore, during the downward acceleration, the spring tension decreases, making the weight of the upper plate greater than the spring tension, thus giving the upper plate a downward acceleration. This allows the upper plate to gradually rise from 0 to 1 m / s. The spring tension changes from being in equilibrium with gravity to being less than gravity, causing the spring to contract. This means the upper plate will move upward relative to the lower plate. According to the capacitor principle formula C = ... As the distance increases, the capacitance value of capacitor C decreases. The capacitance value of capacitor C is converted into a voltage value through a capacitive inertial detection circuit, and then transmitted to the MCU microcontroller through an AD converter. Since the microcontroller has just been woken up, it will determine that the device is in the sinking acceleration phase when the voltage value decreases for the first time. At this time, the flag bit inside the MCU will change from 0 to 1. The state of 1 indicates that the device is in the sinking state.

[0060] Specifically, on-site staff can use a computer to connect to the receiver of the data transmission radio and send an unlock command. The purpose is to prevent accidental triggering during transportation and handling. During transportation and handling, the upper plate of the instrument may vibrate. However, if the data transmission radio does not send an unlock command to wake up the MCU, the MCU will not perform AD voltage detection on the capacitor, thus avoiding accidental triggering.

[0061] 3. Uniform Descending Speed: After accelerating to a speed of 1 m / s, the device will maintain a uniform descent speed (the MCU has anti-jitter logic, so slight speed changes and capacitance fluctuations will not trigger the device to perform corresponding actions). During uniform descent, the MCU will calculate the capacitance value at each sampling moment during acceleration based on the voltage values ​​recorded and collected during acceleration. Then, the corresponding speed value can be simulated according to the formula below: Firstly, the purpose of the Taylor series is to simplify the calculation model and improve the efficiency of the MCU by discarding higher-order terms through Taylor series expansion because the distance the upper plate moves is relatively small. Then, Formula 1 is formed, which first converts the capacitance value into a small displacement.

[0062] This addresses the minute displacements of capacitor plates caused by inertial forces. To address the problem of difficulty in directly and accurately measuring nonlinear functions, this invention introduces a first-order linearization method based on Taylor series. This method transforms nonlinear functions... The deployment is performed near the operating point, effectively overcoming the stability issues caused by direct calculation. Specifically, the system first calibrates the reference capacitance value of the instrument in a stable state. and the corresponding electrode spacing During real-time operation, the main control unit (MCU) obtains the current capacitance value through a high-precision capacitance-to-digital converter (CDC). Furthermore, by utilizing the linear terms of the Taylor expansion, the nonlinear capacitance-displacement relationship is transformed into a linear calculation model, thereby enabling the calculation of minute displacements of the plates. High-sensitivity, high-resolution estimation.

[0063] Formula 1: Capacitance-Displacement Linearization Estimation Model Based on First-Order Taylor Expansion

[0064] in : The minute displacement (in meters, m) of the upper capacitor plates relative to their initial equilibrium positions. Positive values ​​indicate an increase in spacing, while negative values ​​indicate a decrease in spacing.

[0065] The initial distance between capacitor plates in an initial equilibrium state (such as uniform sinking or suspension on the water surface) (unit: meter, m).

[0066] Real-time measured current capacitance value (unit: farad, F).

[0067] Reference capacitance value calibrated under initial equilibrium conditions (unit: farad, F).

[0068] Formula 1 is the cornerstone of the entire algorithm. It transforms the originally complex nonlinear inverse proportional relationship... exist Linearization was performed on the surrounding area. The innovation lies in the fact that it allows the MCU to extract the original capacitor data, which is highly susceptible to noise, with just one simple multiplication or division operation. Converted into a displacement quantity with a clear physical meaning This laid a high-precision data foundation for subsequent acceleration and motion state analysis.

[0069] Formula 2: Formula for calculating inertial acceleration based on Hooke's Law and Taylor model

[0070] in : Inertial acceleration acting on the inertial mass (unit: m / s²). Its direction is the same as the direction of the instrument's motion acceleration.

[0071] : The spring constant of the spring connected to the upper plate (unit: Newton / meter, N / m).

[0072] : Total mass of the upper electrode plate and the inertial mass block connected to it (unit: kilogram, kg).

[0073] , , , : Same as formula 1.

[0074] It is the displacement of the tension spring of the capacitor plate in the initial equilibrium state (that is, the extension of the spring when the upper plate is in equilibrium with the upward spring force and gravity in the initial state).

[0075] Formula 2 describes the physical characteristics of the mechanical system (Hooke's Law). The MCU cleverly combines capacitance data measured electronically, meaning that it does not require an additional accelerometer. It can accurately sense every acceleration and deceleration action of the instrument in the vertical direction, including the critical "bottoming-out impact," simply by measuring capacitance changes.

[0076] Formula 3: Estimation formula for instantaneous sinking velocity based on acceleration integral

[0077] in In time The instantaneous descent velocity of the instrument, estimated at any given time (unit: meters per second, m / s).

[0078] In time The acceleration value calculated from Formula 2 at time 1.

[0079] : The time interval between sampling and calculation by the MCU (unit: seconds, s).

[0080] : The first sampling step during MCU sampling The acceleration value is calculated by solving Formula 2 for the second sampling.

[0081] Number of samples .

[0082] The technical significance and innovation of Formula 3: This formula is the final basis for state determination. It reconstructs the velocity change process of the instrument by performing discrete integration on the acceleration. This invention can be based on... The characteristics are used to accurately divide the work stages: 1. Accelerated sinking phase: It starts from 0 and continues to increase.

[0083] 2. Uniform descent stage: It reaches and stabilizes at a preset value (e.g., 1 m / s).

[0084] 3. The moment of sitting on the ground: A downward step-like zeroing occurs.

[0085] 4. Ascent Phase: It becomes a negative value.

[0086] The judgment logic based on the fusion of multiple parameters of velocity and acceleration provided by this invention is far more reliable and intelligent than the single pressure threshold judgment.

[0087] The calculated sinking speed is also stored so that the sinking status of the seismograph can be known after subsequent salvage.

[0088] 4. Seabed Detection and Low Power Consumption: When the device sinks at a constant speed and touches the seabed, it generates an impact. The overall speed of the instrument rapidly decreases from a constant speed to 0. At this time, the upper electrode plate inside the instrument will change from a state of force balance and constant speed to a state of deceleration with upward acceleration. To achieve this deceleration state, the upper electrode plate will continue to stretch the spring (which can also be understood as the upper electrode plate continuing to move downward due to inertia, thus continuing to stretch the spring). The upper electrode plate moves downward relative to the lower electrode plate, the distance between the electrodes decreases, and the capacitance increases. The capacitance value C is converted into a voltage value by the capacitive inertial detection circuit, and then transmitted to the MC via AD conversion. Within the MCU, since the current internal flag bit is 1, when the detected voltage value increases while the flag bit is 1, it is determined that the current device is in the bottoming-out deceleration phase. During this phase, the upper plate sways up and down due to the impact on the seabed, eventually stabilizing. When the MCU detects that the voltage value is stable, it considers the bottoming-out phase to be over. At this time, the internal flag bit of the MCU will change from 1 to 2. The state of 2 indicates that the device is in the bottoming-out state. At this time, the MCU will record the total time from the initial moment of the device's sinking acceleration to the bottoming-out phase, and this time will also be recorded. At this time, the MCU will maintain the flag bit set to 2 for low power consumption (note that the low power consumption in this state is different from the low power consumption when the device is being handled or transported on the ground, because the presence of the flag bit makes the state when entering low power consumption different. Therefore, the wake-up methods are different in different states: one is wake-up via data transmission radio command, and the other is wake-up via capacitive inertial detection circuit). At this time, the upper plate is stationary (a comparator is added to the capacitive inertial detection circuit, so it is also in a de-jitter state, and slight movement will not wake up the MCU). At this time, the upper plate is in a balanced state, and gravity is equal to the spring tension.

[0089] 5. Ascent and Wake-up Phase: After receiving the acoustic release signal, the main device will discard the load and then ascend. This ascent will cause the main device to ascend synchronously. During ascent, the speed will accelerate from 0 to 1 m / s (for example). During the acceleration ascent, the internal upper plate needs an upward acceleration, which will stretch the spring downward (this can also be understood as the upper plate maintaining a constant speed of 0 due to inertia, while the main device moves upward, thus stretching the spring). At this time, the distance between the upper and lower plates will decrease, and the capacitance value will increase. The capacitance value C is converted into a voltage value by the capacitive inertial detection circuit. If the comparator in the capacitive inertial detection circuit detects that the voltage value change exceeds the threshold, it will wake up the MCU microcontroller. After the MCU microcontroller is woken up, since the current flag bit is 2, and the voltage value collected by the AD converter is increasing, it is determined that the current device state is the ascent state, and the flag bit is set to 3. The state 3 indicates that the device is in the ascent state.

[0090] 6. Once the device enters the surfacing state (i.e., when the flag is 3), the MCU will extract the total time recorded from the initial moment of the device's descent acceleration to the moment it reaches the bottom. A delay of 0.8 times this total time will be applied. The purpose is to minimize high power consumption before the device surfaces. The 0.8-times delay is to activate all sensors before the device surfaces, ensuring timely updates to all states after surfacing. After the delay, the MCU will collect the current positioning signal via GPS, and the data transmission radio will simultaneously broadcast a handshake command carrying GPS positioning information, while the LED lights will flash.

[0091] 7. Once in the surfacing state, the capacitive inertial detection circuit and upper pole plate do not require vibration. After the instrument ascends, the power supply to the capacitive inertial detection circuit will be cut off. At this time, a locking device will lock the upper pole plate. The locking device is an electric telescopic rod, which is fixed to the same position as the spring on a plane with a cable passage hole in the center of the cabin. Normally, the push rod end of the telescopic rod will not contact the upper pole plate. Only during surfacing and locking will the telescopic rod extend until it hits the upper pole plate, allowing it to move downwards against the upper pole plate. Tightening involves pushing the upper electrode plate downwards until it contacts the lower electrode plate, while simultaneously detecting the stall current of the electric telescopic rod motor. When the stall current reaches a set threshold, the telescopic rod stops extending and retracting. At this point, the upper and lower electrode plates are in contact, completing the locking. This locking device will automatically release when the staff resets the instrument after the equipment is retrieved and recovered. After resetting, the MCU microcontroller will clear the total stored duration and flag bits to zero. Then, after fully charging, the device will enter a low-power mode and wait for the next use after being attracted to the magnetic control switch inside the device by a magnet for more than 5 seconds.

[0092] The above are the working steps and process of the entire equipment.

[0093] Compared with the prior art, the present invention has the following significant advantages: 1. High positioning accuracy: The latitude and longitude coordinates obtained by GPS are directly transmitted through a data transmission radio, and the positioning error can be controlled within a few meters, which is far superior to acoustic positioning. The mother ship can sail directly to the target point, greatly shortening the search time.

[0094] 2. High search efficiency: The combination of "strong light visual guidance" and "radio data guidance" enables efficient searching around the clock. Even at night or in inclement weather, the strong light allows the mother ship to detect targets at a considerable distance.

[0095] 3. High system reliability: The system adopts the capacitive sensing principle instead of mechanical switches, which fundamentally eliminates the risk of misjudgment or failure caused by component jamming, and can adapt to the extreme environment of the deep sea.

[0096] 4. Ultra-low power consumption operation: The innovative hibernation-wake mechanism enables the instrument to maintain basic monitoring functions with only a small amount of power during a year-long underwater operation, effectively ensuring the mission's endurance.

[0097] 5. High data value: Attitude data recorded during the subsidence phase provides an important reference for assessing the quality of seismic data.

[0098] Example 2: In this embodiment 2, the subsea seismograph's floating positioning and locating device is encapsulated in a titanium alloy cabin with a diameter of 10cm and a height of 20cm. Inside the cabin, at the center, a 50g brass mass block suspended by three disc springs forms a capacitive sensor. An STM32 series MCU is used, integrating a LoRa RF module and an MPPT controller. A 5W flexible solar panel is mounted on top.

[0099] Hardware Connection and Initialization: The main control unit (MCU) uses an STM32L series low-power microcontroller. After power-on, the MCU first executes a self-test program to initialize all I / O ports and peripherals, and then enters the main loop. After entering low power mode by magnetic attraction, it enters the default state. In the default state, except for the capacitor detection, all other modules are powered off, and the MCU and data transmission radio are in low power mode.

[0100] Descending and Recording Phase: After the instrument is placed in the water, the operator activates the MCU, which reads the values ​​from the capacitive inertial measurement unit at a frequency of 1Hz. The MCU internally stores a threshold value for the capacitance. As the instrument descends, the capacitance value decreases; when it reaches the threshold, the descent process is considered complete. At this point, the MCU outputs a control signal to power on the attitude sensor (such as Analog Devices' ADIS16470). The attitude sensor begins operating, and the MCU reads its output triaxial angular velocity, acceleration, and magnetometer data at a frequency of 10Hz via the SPI interface. After processing with a fusion filtering algorithm, the MCU calculates the instrument's pitch, roll, and yaw angles and stores this data, along with a timestamp, in the EEPROM.

[0101] Bottom-up Sleep Phase: When the MCU detects a capacitance spike of 180pF, it determines "bottom-up successful," shuts down the attitude sensor, and then determines that the instrument has stabilized on the bottom, shutting down the attitude sensor and entering sleep mode. The MCU then sends a power-off command to the attitude sensor via the GPIO port and shuts down its power. The MCU itself calls the WFI (Wait For Interrupt) instruction to enter STOP mode, and the system clock is reduced to the minimum. The MCU's internal RTC (Real-Time Clock) wakes the MCU once every 24 hours. The MCU only needs milliseconds to check for abnormal changes in the capacitance value; if there is no change, it re-enters STOP mode.

[0102] Ascent Activation Phase: During recovery operations, the mother ship sends an acoustic command or at a predetermined time, and the instruments activate the surfacing motor to release the ballast. As the speed increases, the capacitance value also increases. When the capacitance value exceeds a comparison threshold, the MCU is awakened. The awakened MCU immediately exits STOP mode, waking up the entire system.

[0103] Active positioning and localization phase: The MCU first pulls the level high to start the GPS module (such as the U-blox M8P). The GPS module's antenna begins searching for satellite signals through the wave-transparent window of the pressure-resistant housing. After about 30 seconds, the GPS module obtains a valid GGA statement in NMEA-0183 format.

[0104] At the same time, the MCU controls three high-power blue LED beads connected externally via PWM (pulse width modulation) port, making them blink in a cycle of "on for 0.5 seconds, off for 0.5 seconds", and the brightness can be seen by the naked eye from hundreds of meters away.

[0105] If no instructions are received from the mother ship after 15 minutes of ascent, the "low-frequency acoustic beacon" (12kHz) will be activated.

[0106] After surfacing for one hour, the "high-brightness blue-green LED array" is activated, flashing in a "three short and one long" SOS mode. By utilizing the penetrability of blue-green light in water and the high sensitivity of the human eye, it can achieve efficient visual positioning at night or in turbid water.

[0107] The MCU reads the data stream output by the GPS module via serial port, parses out the longitude and latitude information, and packages it into data frames according to a custom protocol, for example: `$OBS_POS,39.123456,N,118.654321,E,` CC\r\n`; Where $OBS_POS represents the data frame header. CC\r\n indicates the end of the frame and a newline. 39.123456,N,118.654321,E represents latitude and longitude coordinates. N represents North latitude, and the value before N is the North latitude coordinate. E represents East longitude, and the value before E is the East longitude coordinate.

[0108] The MCU activates the data radio module (such as Silicon Labs' SI4463) to broadcast the data frame in a loop at a baud rate of 9600bps with a transmission power of 500mW. Theoretically, the communication distance in open sea areas can reach more than 5 kilometers.

[0109] Solar charging: The device floats on the water surface, and the MPPT controller starts working to charge the battery.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0111] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A smart recovery system for a seabed seismograph based on inertial triggering and multimodal sensing, characterized in that, include: A sealed pressure chamber, and a main control unit, a capacitive inertial detection unit, an attitude sensor, a GPS module, a data transmission radio module, an LED flash assembly, and a power management module installed inside the pressure chamber; The capacitive inertial detection unit is connected to the main control unit and is used to sense the motion state of the instrument. An attitude sensor, connected to the main control unit, is used to collect three-dimensional attitude data after being woken up; The GPS module is connected to the main control unit and is used to obtain positioning information after the instrument floats to the surface of the water; The data transmission radio module, connected to the main control unit, is used to send data packets containing the positioning information to the outside world; An LED flash assembly, connected to the main control unit, is used to emit light signals at night or in low-visibility environments. The power management module connects to the main control unit, capacitive inertial detection unit, attitude sensor, GPS module, data radio module, and LED flash assembly, and provides energy management.

2. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 1, characterized in that, The capacitive inertial detection unit includes a fixed lower electrode plate of a capacitor fixed inside the chamber, and a movable upper electrode plate of a capacitor suspended above the fixed lower electrode plate by an elastic element. The movable upper electrode plate moves relative to the fixed lower electrode plate as the instrument moves, thereby changing the capacitance value.

3. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 2, characterized in that, The capacitive inertial detection unit also includes a capacitor-to-digital converter connected to the main control unit, used to convert the real-time capacitance value between the upper plate of the movable capacitor and the lower plate of the fixed capacitor into a digital signal and transmit it to the main control unit.

4. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 3, characterized in that, The main control unit determines the sinking, bottoming, and floating states of the instrument by detecting changes in the capacitance value, and switches the system's working mode according to different states.

5. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 4, characterized in that, The main control unit pre-stores a capacitance-displacement linearization estimation model based on first-order Taylor expansion, which is used to convert the real-time acquired capacitance values ​​into displacement values. The formula is as follows: in, This represents the minute displacement of the upper capacitor plate relative to its initial equilibrium position. The initial spacing between the capacitor plates in the initial equilibrium state; This represents the current capacitance value measured in real time. This is the reference capacitance value calibrated under the initial equilibrium state.

6. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 5, characterized in that, The main control unit also pre-stores an inertial acceleration calculation formula based on Hooke's law, which is used to convert the displacement into an acceleration value. The formula is as follows: in, This refers to the inertial acceleration acting on the inertial mass block. The spring constant of the spring connected to the upper electrode plate; The total mass of the upper electrode plate and the inertial mass block connected to it; It is the acceleration due to gravity; This represents the displacement of the tension spring of the capacitor plate in the initial equilibrium state, that is, the elongation of the spring when the upper plate is in equilibrium with the upward spring force and gravity.

7. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 6, characterized in that, The main control unit also pre-stores an instantaneous velocity estimation formula based on acceleration integral, which is used to estimate the instrument's instantaneous sinking or surfacing velocity by performing discrete-time integration on the acceleration value. The formula is as follows: in, In time The instantaneous descent velocity of the instrument, estimated at all times; In time The acceleration value calculated from Formula 2 at time 1; The time interval for the MCU to perform sampling and calculation; For the first sampling during MCU The acceleration value obtained from the second sample is calculated using formula two. For the number of samples, .

8. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 1, characterized in that, It also includes a magnetic switch electrically connected to the main control unit; the magnetic switch is used to close under the attraction of an external magnet, triggering the system to enter a low-power lock-up state for transportation and storage.

9. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 1, characterized in that, It also includes a flexible solar panel mounted on top of the pressure chamber, and a maximum power point tracking charge controller electrically connected to the solar panel and the power management module, for auxiliary charging of the system when the instrument is on the water surface.

10. The intelligent recovery system for a seabed seismograph based on inertial triggering and multimodal sensing according to claim 3, characterized in that, The capacitive inertial detection unit also includes a locking device, which is an electric telescopic rod electrically connected to the main control unit. When the main control unit determines that the instrument has entered the floating state, it controls the electric telescopic rod to extend and press against the upper electrode of the movable capacitor until it contacts and locks against the lower electrode of the fixed capacitor, and at the same time shuts off the power supply of the capacitive inertial detection unit.

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