Long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels

Abstract

The present invention relates to a long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels, and its main technical features are: including a communication buoy body and its wireless communication module, a main control chip, a modulation and demodulation module, an amplification and filtering module, a hydroacoustic transducer, a transducer driving module, a power module, a voltage stabilization and voltage reduction module, a solar panel and a charging control module; on the water surface, the wireless communication module can be used to communicate with a host computer, and under the water surface, the hydroacoustic transducer is used to convert an electrical signal into a hydroacoustic signal and send it out, or the received hydroacoustic signal is converted into an electrical signal and then sent to the host computer through the wireless communication module. The present invention realizes the function of being able to communicate with a host computer on the water surface using a wireless communication module, and the solar panel is used to supplement the power supply module with electricity under the control of the charging control module and the clock frequency control algorithm in the main control chip, which can effectively improve the endurance of the equipment.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and relates to underwater monitoring equipment, in particular to a long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and a solar panel. Background Art

[0002] At present, there are two main communication methods between various underwater monitoring equipment including underwater robots and surface computers, namely cabled and cableless communication methods.

[0003] Cable communication is mainly carried out in the form of power carrier lines. This communication method has high speed and good stability, and can achieve real-time communication, completing the real-time communication between the host computer and the underwater monitoring equipment. However, the cable length greatly limits the operating range of the monitoring equipment, and the cable is prone to entanglement. Its flexibility and adaptability are low, and as the cable length increases, the cost and communication power of the underwater monitoring equipment also increase greatly.

[0004] Cableless communication is mainly accomplished by hydroacoustic modems. When underwater monitoring equipment monitors hydrology, geology, etc. for a long time under the water surface, the hydroacoustic modem modulates the electrical signal into an acoustic signal, and then transmits it in the hydroacoustic channel. This communication method has a long transmission distance, and the deployment and operation of underwater monitoring equipment are more flexible. However, the time point of communication and the amount of data transmitted are random. If the STM32 works at a fixed high clock frequency for a long time, it will consume a lot of power. When it is independently deployed on the water surface, it will increase the load on the battery, thereby affecting its endurance. Therefore, it is difficult to be used independently in a surface operation environment for a long time.

[0005] In summary, how to increase the endurance of communication buoys and their flexible wireless communication capabilities is an issue that needs to be urgently addressed. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels, which can functionally meet the wireless communication function between the host computer and the underwater monitoring equipment, and use solar energy devices and clock frequency control algorithms to improve endurance.

[0007] The present invention solves the technical problem by adopting the following technical solutions:

[0008] A long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels, including a communication buoy body, on which the following modules are installed:

[0009] Main control chip: connected with wireless communication module and modulation and demodulation module to realize overall control function;

[0010] Wireless communication module: connected to the main control chip, used for the buoy to communicate with the host computer on the water surface;

[0011] Modulation and demodulation module: connected to the amplification and filtering module and the transducer driving module, used to convert the analog signal received by the underwater acoustic transducer into a digital signal, or convert the digital signal output by the main control chip into an analog signal;

[0012] Amplification and filtering module: connected to the modulation and demodulation module and the underwater acoustic transducer, used to amplify and filter the analog signal;

[0013] Transducer driving module: connected with the modulation and demodulation module and the underwater acoustic transducer to provide energy for sending the underwater acoustic signal;

[0014] Hydroacoustic transducer: connected to the amplification and filtering module and the transducer driving module, used to convert the received hydroacoustic signal into an electrical signal, or convert the electrical signal into a hydroacoustic signal and send it out;

[0015] Solar panel: connected to the charging control module, used to convert solar energy into electrical energy and store it in the power module;

[0016] Charging control module: connected with the solar panel and the power module, used to control the charging process of the solar panel to the power module;

[0017] Power module: connected to the charging control module and the voltage stabilizing and step-down module, used to store the energy transmitted from the solar panel and provide power for the entire system;

[0018] Voltage stabilizing and step-down module: connected to the power module, used to filter and step down the voltage of the power module, and then supply it to different modules of the system for use.

[0019] Furthermore, the communication buoy body includes a sealed cabin and a bracket, the bracket is installed at the upper end of the sealed cabin, a bracket seat is installed on the bracket, a solar panel and an antenna are installed on the bracket seat, a floating body is set on the outside of the sealed cabin to provide buoyancy and maintain balance, a circuit board mounting seat is installed inside the sealed cabin, a circuit board and a power module are installed on the mounting seat, the power module is connected to the solar panel, and a ballast weight for maintaining the stability of the sealed cabin is installed at the bottom of the sealed cabin; the hydroacoustic transducer is installed below the sealed cabin through a transducer cable, and a weight is connected to the bottom of the hydroacoustic transducer to prevent the cable from being entangled.

[0020] Furthermore, the main control chip adopts an STM32 series chip, which communicates with the wireless communication module via an SPI interface.

[0021] Furthermore, the charging control module is composed of a BUCK circuit, a voltage detection device, a photosensor, an AND gate circuit, a PID controller, and a MOS tube driver chip; the voltage detection device and the photosensor are connected to a PID controller through an AND gate circuit, the PID controller controls the MOS tube driver chip, and the MOS tube in the BUCK continuously adjusts the conduction duty cycle under the drive of the MOS tube driver chip, so that the voltage output from the solar panel to the power supply is also continuously adjusted. When the power supply voltage rises too fast or approaches the rated voltage, the duty cycle is reduced, that is, the charging voltage is reduced, otherwise the duty cycle is increased and the charging voltage is increased.

[0022] Furthermore, a clock frequency control algorithm is installed in the main control chip to predict the time when the communication request occurs in the next 24 hours, and set the chip clock frequency for the next 24 hours accordingly, so as to reduce the power consumption of the main control chip.

[0023] Furthermore, the clock frequency control algorithm includes the following steps: first, a prediction function is generated using the communication request time of the previous day, then a prediction coefficient is generated using the number of communication requests in the previous three days, and finally a total prediction function is generated based on the prediction function and the prediction coefficient, and the clock frequency for the next 24 hours is determined based on this.

[0024] Furthermore, the clock frequency prediction method also includes: after a day's communication ends, the actual communication time point is compared with the predicted communication time point to generate an error value E. When E is greater than a certain value, the prediction is considered inaccurate, and it is necessary to re-count the communication time points for three days and generate a new predicted frequency; when E is less than a certain value, the prediction is considered accurate, and the data of the previous two days is retained and supplemented with the data of the current day to predict the frequency of the next day.

[0025] The advantages and positive effects of the present invention are:

[0026] 1. The present invention is reasonably designed. The STM32 main control chip on the circuit board controls the underwater acoustic transducer to detect signals through the modulation and demodulation module. After receiving the detection signal of the underwater acoustic transducer, it communicates with the host computer through the wireless communication module and sends the signal to the host computer, thereby realizing the function of communicating with the host computer by using the wireless communication module on the water surface, and converting the electrical signal into the underwater acoustic signal and sending it out by using the underwater acoustic transducer under the water surface, or converting the received underwater acoustic signal into the electrical signal and then sending it to the host computer through the wireless communication module. In addition, the present invention replenishes the power supply module with electricity through the solar panel under the control of the charging control module, which can effectively improve the endurance of the equipment.

[0027] 2. The present invention uses the clock frequency control algorithm in the STM32 main control chip to dynamically adjust the clock operating frequency, thereby effectively reducing the power consumption of the STM32 main control chip and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the communication buoy structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the topological connection between the communication buoy modules of the present invention;

[0030] Figure 3 is a circuit diagram of a transducer driving circuit of the present invention;

[0031] Figure 4 This is a schematic diagram of the charging control module circuit of the present invention;

[0032] Figure 5 This is a flow chart of the clock frequency control algorithm of the main control chip of the present invention;

[0033] Figure 6 Schematic diagram of the probability of requesting communication at time t;

[0034] In the figure, 1-antenna, 2-solar panel, 3-bracket, 4-circuit board, 5-bracket seat, 6-power module, 7-floating body, 8-circuit board mounting seat, 9-ballast weight, 10-sealed cabin, 11-cable, 12-hydroacoustic transducer, 13-weight. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings.

[0036] A long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar energy devices, such as Figure 1 As shown, the communication buoy body includes a sealed cabin 10, a bracket 3 and a hydroacoustic transducer 12, the bracket is installed at the upper end of the sealed cabin, a bracket seat 5 is installed on the bracket, a solar panel 2 and an antenna 1 are installed on the bracket seat, a floating body 7 is set around the outside of the sealed cabin to provide buoyancy and maintain balance, a circuit board mounting seat 8 is installed inside the sealed cabin, a circuit board 4 and a power module 6 are installed on the mounting seat, and the power module is connected to the solar panel, and a ballast weight 9 for maintaining the stability of the sealed cabin is installed at the bottom of the sealed cabin. The hydroacoustic transducer 12 is installed at the bottom of the sealed cabin through a transducer cable 11, and a weight is connected to the bottom of the hydroacoustic transducer to prevent the cable from being entangled.

[0037] like Figure 2As shown, the circuit board in the sealed cabin includes a wireless communication module, a main control chip, a modulation and demodulation module, an amplification and filtering module, a transducer driving module, a voltage stabilization and bucking module, and a charging control module. The main control chip is connected to the wireless communication module and the modulation and demodulation module, and the modulation and demodulation module is connected to the amplification and filtering module and the transducer driving module, and the amplification and filtering module and the transducer driving module are connected to the hydroacoustic transducer. The charging control module is connected to the solar panel to charge the power module, and the buck and voltage stabilization circuit is connected to the power module to output a stable voltage to power the main control chip, the wireless communication module, the modulation and demodulation module, the amplification and filtering module, and the transducer driving module.

[0038] The wireless communication module is connected to the antenna on the bracket, and the wireless communication module communicates wirelessly with the host computer under the control of the STM32 main control chip. In this embodiment, the wireless communication module selects an integrated wireless communication chip, and the specific model is selected but not limited to nRF24L01. The wireless communication chip integrates a frequency generator, an enhanced controller, a power amplifier, a modem, etc., and can select channels and set protocols through the SPI interface. Its operating voltage is 3.3V to 5.0V.

[0039] The modulation and demodulation module is used to amplify the analog signal transmitted by the filter module and modulate it into a digital signal that can be recognized by the STM32 main control chip, or modulate the digital signal that the main control chip needs to send into an analog signal, and then transmit it to the transducer drive module. In this embodiment, the modulation and demodulation module selects the MSM7512 series chip designed and produced by OKI, which has a baud rate of 1200, a power supply voltage of 3.0V to 5.0V, four working modes, and a low price.

[0040] In this embodiment, the main control chip is used as the core control module, and is selected from but not limited to the STM32 series chips of STMicroelectronics (ST). The clock frequency of the chip can be dynamically adjusted, the power supply voltage is 2.0V to 3.6V, the maximum operating frequency can reach 72MHz, and it has a relatively rich peripheral interface.

[0041] When the STM32 main control chip needs to send an underwater acoustic signal, it passes the digital information to the modulation and demodulation module. The modulation and demodulation module modulates the digital signal into an analog signal and passes it to the transducer driving module. After receiving the analog signal to be sent, the transducer driving module generates the high voltage required to drive the transducer, and then loads the high voltage onto the underwater acoustic transducer to drive the underwater acoustic transducer to send an underwater acoustic signal into the water.

[0042] When the STM32 main control chip receives an underwater acoustic signal, the sound wave vibration will cause the thin sheet of the underwater acoustic transducer to vibrate, thereby generating a corresponding tiny voltage signal. The amplification and filtering module amplifies and filters the signal to obtain a relatively pure analog signal, which is then converted into a digital signal that can be recognized by the chip after passing through the modulation and demodulation module.

[0043] like Figure 3 As shown, the transducer drive module adopts an integrated drive chip, and the model is the IR2117 drive chip produced by IR Company. The point where the high voltage of the transducer drive module is loaded on the transducer is also the point where the amplifying filter circuit receives a tiny signal. Since the transducer is a transceiver, it is possible to receive signals while sending signals. If the voltage limiting measures are not taken, when the higher transmission voltage of the drive circuit is directly loaded on the receiving circuit, the components of the receiving circuit will be burned, thereby causing the entire system to be paralyzed. In order to prevent the high voltage from damaging the amplifying filter circuit when receiving and sending are carried out simultaneously, a limiting circuit is added at this point, that is, a resistor with a resistance of 200 kilo-ohms, two capacitors of 0.1 microfarads and two diodes are added before the ultrasonic signal. When the high voltage directly acts on the receiving circuit, the current first passes through the current limiting resistor, and the diode is turned on at this time. The conduction of the diode loop causes the diode 0.7V conduction voltage to be loaded on the receiving end, so that the subsequent circuit will not be affected. When the receiving end receives the sound wave signal, the voltage of the millivolt level cannot turn on the diode, so that the signal is transmitted to the receiving end processing circuit.

[0044] The amplification and filtering module is mainly composed of a power amplification circuit, a voltage amplification circuit and a bandpass filtering circuit.

[0045] The model adopted by the hydroacoustic transducer is a transceiver-transducer, which not only sends hydroacoustic signals to other underwater information nodes, but also receives hydroacoustic signals sent by other hydroacoustic transducers and converts them into electrical signals. It requires a higher voltage to send hydroacoustic signals.

[0046] The power module is a lithium battery that can be repeatedly charged and discharged, and its discharge voltage is 12V.

[0047] The charging control module uses a BUCK circuit to charge the lithium battery and monitor the lithium battery voltage. When the battery voltage is close to 12V or rises too fast, the duty cycle is reduced, otherwise the duty cycle is increased. This control process uses PID control. Figure 4As shown, the charging control module circuit is composed of a BUCK circuit, a voltage detection device, a photosensitive sensor, an AND gate circuit, a PID controller, and a MOS tube driver chip. The voltage detection device and the photosensitive sensor are connected to a PID controller through an AND gate circuit. The PID controller controls the MOS tube driver chip. The MOS tube in the BUCK continuously adjusts the conduction duty cycle under the drive of the MOS tube driver chip, so that the voltage output from the solar panel to the power supply is also continuously adjusted. If the power supply voltage rises too fast or is close to the rated voltage, the duty cycle is reduced, that is, the charging voltage is reduced. Otherwise, the duty cycle and the charging voltage are increased. This can prevent overcharging from causing damage to the battery. When the voltage detection device detects that the voltage is lower than a certain critical value, it will send a signal. If the photosensitive element also senses a certain light intensity, the AND gate is turned on, and the battery starts to charge. After the battery is fully replenished, if the voltage detection device detects that the voltage rises to a normal value, the device will automatically reset and charging will end. During the control process of this charging control module, the solar panel power generation voltage is higher than the power supply voltage, and the solar panel charges the power module through the BUCK circuit. The solar panel will only charge the power module when the power monitoring module detects that the power supply voltage is lower than the critical value and the light value of the photosensor is greater than a certain value.

[0048] The solar panel is a micro photovoltaic panel with an output voltage of 15V. Its area is about 100 square centimeters, its shape is square, and it is attached above the communication buoy. After passing through the charging control module, the solar panel is connected to the rechargeable power module. When the voltage detection module detects that the power supply voltage is low and the light sensor senses a certain light intensity, the BUCK circuit will be turned on under the control of the PID algorithm and continuously adjust the duty cycle according to the charging situation to prevent overcharging. The buck regulator chip filters the power supply voltage and reduces it to different levels of voltage for the main control chip and other modules.

[0049] The voltage regulator and buck module uses an integrated voltage regulator and buck chip, and its model is selected from but not limited to the LM2675 series buck chip, which can convert the 12V input voltage into 5V for use in wireless communication modules and modulation and demodulation modules. It is selected from but not limited to the AMS1117-3.3 voltage regulator chip, which converts the 5V voltage into 3.3V voltage for use in the main control chip.

[0050] In order to reduce the power consumption of the chip as much as possible, the STM32 main control chip adopts Figure 5The clock frequency control algorithm shown is used to predict and adjust the system clock frequency. The specific instructions are as follows: First, the system is turned on and initialized, and then runs at the maximum clock frequency for three days, that is, 72 hours. During this process, the number of communications per day is recorded, set as n1, n2, and n3, and the time of request communication from the third day, that is, from the 49th hour to the 72nd hour, is recorded. Suppose there are n times in total, namely t1, t2, t3…tn. A plane rectangular coordinate system is established with time as the horizontal coordinate, one hour as a unit length, and probability P as the vertical coordinate. Substitute t1, t2, t3…tn into the formula μ in the form Figure 6 As shown in the image (taking t1 and t2 as examples), these n functions are added together and then divided by n, and the resulting function is the clock frequency prediction function f obtained based on the data from 49h to 72h.

[0051] Then, a quadratic spline interpolation function Y=g(x) is obtained based on the coordinate points (1, n1), (2, n2), and (3, n3). Substituting n=4 into x, the prediction number n4 for the fourth day is obtained, and the prediction ratio coefficient k is obtained using the formula k=n4÷n3. The calculation formula of the total prediction function F is F=k*f. If the value of F is greater than 1, F is set to 1. Since the clock frequency can only be 8MHz and its integer multiples, and the maximum is 64MHz, the specific frequency is determined according to the following rules: when F is greater than 0 and less than or equal to 0.125, the clock frequency is set to 8MHz; when F is greater than 0.125 and less than or equal to 0.25, the clock frequency is set to 16MHz; when F is greater than 0.25 and less than or equal to 0.375, the clock frequency is set to 24MHz; when F is greater than 0.375 and less than or equal to 0.5, the clock frequency is set to 32MHz; when F is greater than 0.5 and less than or equal to 0.625, the clock frequency is set to 40MHz; when F is greater than 0.625 and less than or equal to 0.75, the clock frequency is set to 48MHz; when F is greater than 0.75 and less than or equal to 0.875, the clock frequency is set to 56MHz; when F is greater than 0.875 and less than or equal to 1, the clock frequency is set to 64MHz.

[0052] After obtaining the above-mentioned predicted clock frequency, the data of the second day is set as that of the first day, and the data of the third day is set as that of the second day. Then, the system is operated according to the predicted clock frequency, and the data of the time when communication is requested is recorded. After 24 hours, the data of this day is regarded as the data of the third day, that is, the time when communication is requested within 49 hours to 72 hours mentioned above.

[0053] The algorithm for calculating the prediction error is as follows: suppose there are a number of communication request times in the previous day, namely t1, t2…ta, and there are b number of communication request times after the end of the day, namely T1, T2…Tb, then the calculation formula for the error E is: If E is greater than 1, it is judged that the regularity of requesting communication has changed, resulting in a large error and the need to re-record and obtain a new prediction function. If E is less than 1, it is judged that the time regularity of requesting communication has not changed, and the frequency value of the next day can be predicted on this basis.

[0054] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels, comprising a communication buoy body, characterized in that: The following modules are installed on the buoy body: Main control chip: connected with wireless communication module and modulation and demodulation module to realize overall control function; Wireless communication module: connected to the main control chip, used for the buoy to communicate with the host computer on the water surface; Modulation and demodulation module: connected to the amplification and filtering module and the transducer driving module, used to convert the analog signal received by the underwater acoustic transducer into a digital signal, or convert the digital signal output by the main control chip into an analog signal; Amplification and filtering module: connected to the modulation and demodulation module and the underwater acoustic transducer, used to amplify and filter the analog signal; Transducer driving module: connected with the modulation and demodulation module and the underwater acoustic transducer to provide energy for sending the underwater acoustic signal; Hydroacoustic transducer: connected to the amplification and filtering module and the transducer driving module, used to convert the received hydroacoustic signal into an electrical signal, or convert the electrical signal into a hydroacoustic signal and send it out; Solar panel: connected to the charging control module, used to convert solar energy into electrical energy and store it in the power module; Charging control module: connected with the solar panel and the power module, used to control the charging process of the solar panel to the power module; Power module: connected to the charging control module and the voltage stabilizing and step-down module, used to store the energy transmitted from the solar panel and provide power for the entire system; Voltage stabilizing and voltage reducing module: connected to the power module, used to filter and reduce the voltage of the power module, and then supply it to different modules of the system; The main control chip is installed with a clock frequency control algorithm for predicting the time when the communication request will occur in the next 24 hours, and setting the chip clock frequency for the next 24 hours accordingly, so as to reduce the power consumption of the main control chip; The clock frequency control algorithm comprises the following steps: firstly, generating a prediction function using the communication request time of the previous day, then generating a prediction coefficient using the communication request times of the previous three days, and finally generating a total prediction function based on the prediction function and the prediction coefficient, and determining the clock frequency for the next 24 hours based on the total prediction function; The clock frequency prediction method also includes: after a day's communication ends, the actual communication time point is compared with the predicted communication time point to generate an error value E. When E is greater than a certain value, it is considered that the prediction is inaccurate, and it is necessary to re-count the communication time points for three days and generate a new predicted frequency; when E is less than a certain value, it is considered that the prediction is accurate, and the data of the previous two days is retained and supplemented with the data of the current day to predict the frequency of the next day.

2. The long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels according to claim 1 is characterized in that: The communication buoy body includes a sealed cabin and a bracket, the bracket is installed at the upper end of the sealed cabin, a bracket seat is installed on the bracket, a solar panel and an antenna are installed on the bracket seat, a floating body is set on the outside of the sealed cabin to provide buoyancy and maintain balance, a circuit board mounting seat is installed inside the sealed cabin, a circuit board and a power module are installed on the mounting seat, the power module is connected to the solar panel, and a ballast weight for maintaining the stability of the sealed cabin is installed at the bottom of the sealed cabin; the hydroacoustic transducer is installed below the sealed cabin through a transducer cable, and a weight is connected to the bottom of the hydroacoustic transducer to prevent the cable from being entangled.

3. The long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels according to claim 1 or 2, characterized in that: The main control chip adopts an STM32 series chip, which communicates with the wireless communication module via an SPI interface.

4. The long-endurance cross-medium communication buoy for underwater monitoring based on STM32 and solar panels according to claim 1 or 2, characterized in that: The charging control module is composed of a BUCK circuit, a voltage detection device, a photosensor, an AND gate circuit, a PID controller, and a MOS tube driver chip. The voltage detection device and the photosensor are connected to a PID controller through an AND gate circuit. The PID controller controls the MOS tube driver chip. The MOS tube in the BUCK continuously adjusts the conduction duty cycle under the drive of the MOS tube driver chip, so that the voltage output from the solar panel to the power supply is also continuously adjusted. When the power supply voltage rises too fast or approaches the rated voltage, the duty cycle is reduced, that is, the charging voltage is reduced. Otherwise, the duty cycle is increased and the charging voltage is increased.

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