Acoustic remote control device for bionic robotic fish and method thereof

Abstract

An acoustic remote control device and method for a bionic robotic fish, relate to underwater acoustic telemetry remote control. The device is composed of an acoustic emission module, an acoustic receiving module and a remote control terminal. The data of the remote control terminal is output to the acoustic emission module through wireless communication, the data of the acoustic emission module is output to the acoustic receiving module through acoustic communication, and the acoustic receiving module outputs control instructions to the bionic robotic fish through an RS232 serial port. The acoustic emission module is used to receive instructions from the remote control terminal through a wireless transceiver, complete channel coding, modulation and underwater acoustic signal transmission of the remote control instructions. The bandwidth of the underwater acoustic emission transducer is divided into two sub-bands B1 and B2. User instruction data is grouped by Hamming coding, information bits are sent through the B1 sub-band, and check bits are sent through the B2 sub-band. The remote control terminal receives user instructions through a remote control panel, source encodes the user instructions, and sends the encoded data to the acoustic emission module through a wireless transceiver.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater acoustic telemetry remote control, and particularly relates to an acoustic remote control device for a bionic robotic fish and a method thereof. BACKGROUND

[0002] Underwater robots play a huge role in reducing the cycle and cost of ocean development, reducing the risk of underwater detection and the convenience of replacing manual detection, and have become one of the hotspots of research in the world. Through further improvement and innovation of acoustic telemetry remote control of underwater robots, the goal of human exploration of the ocean and utilization of ocean resources for production and life has become a new ocean technology. The development of small underwater robots with smaller size and better operability, whose size ranges from a few centimeters to one meter, has become an increasingly concerned field. Bionic robotic fish is a small underwater robot designed in the shape of a bionic fish and the swimming mode. Compared with traditional underwater robots, bionic robotic fish has the advantages of realistic shape, high efficiency, quietness and flexibility, making it possible for humans to observe fish activities at close range and interact with marine life (Webb PW.Body Form, Locomotion and Foraging in Aquatic Vertebrates [J]. American Zoologist, 1984, 24(1): 107-120).

[0003] Important progress has been made in the research of biomimetic robotic fish at home and abroad. For example, the MIT Distributed Robotics Laboratory in the United States has successfully researched Robotuna, VCUUV and Alvarado, etc. three generations of biomimetic robotic fish since 1994 (Robert K. Katzschmann, Joseph DelPreto, Robert MacCurdy, et al. Exploration of underwater life with an acoustically controlled soft robotic fish [J]. Science Robotics, 2018, 3(16), eaar3449). Beijing University of Aeronautics and Astronautics has developed robotic dolphins, biomimetic manta rays, SPC series, etc. robotic fish, among which the SPC-II robotic fish participated in the underwater shipwreck archaeological work in 2004 (Liang Jianhong, Zou Dan, Wang Song, et al. SPC-II robotic fish platform and its autonomous navigation experiment [J]. Journal of Beijing University of Aeronautics and Astronautics, 2005(07):709-713). However, it is still a big challenge to remotely control the biomimetic robotic fish, and various control methods have their limitations: (1) the range of traditional cable control is limited, and it is easy to form cable breakage and cable twisting accidents; (2) the control based on radio communication has the shortcomings of fast attenuation of electromagnetic short waves in water and complex reception of long waves; (3) the control based on optical communication has the problems of large attenuation and easy influence of surrounding light scattering and suspended particles. Sound wave is a mechanical wave, which has small attenuation and long transmission distance in water, so it is suitable for being used as the carrier of control information transmission of biomimetic robotic fish. In recent years, the digital underwater acoustic communication technology has developed rapidly, and various underwater acoustic Modems with different modulation methods and different communication rates have appeared on the market. However, these underwater acoustic Modems have high power consumption, large size, high price and cannot be customized, so they are difficult to be applied to the remote control field of biomimetic robotic fish. SUMMARY

[0004] The purpose of the present application is to provide a small, low-power and embedded acoustic remote control device and method for biomimetic robotic fish and other small underwater robots.

[0005] The biomimetic robotic fish acoustic remote control device is composed of an acoustic emission module, an acoustic receiving module and a remote control terminal. The data of the remote control terminal is output to the acoustic emission module through wireless communication, the data of the acoustic emission module is output to the acoustic receiving module through acoustic communication, and the acoustic receiving module outputs control instructions to the biomimetic robotic fish through the RS232 serial port.

[0006] The hardware system of the acoustic emission module comprises a wireless transceiver, an embedded CPU and its peripheral circuit, a power amplification circuit, a power conversion circuit and a underwater acoustic emission transducer, the wireless transceiver communicates with the embedded CPU through an RS232 serial port, digital signals generated by the embedded CPU are output to the power amplification circuit after D / A conversion, the output of the power amplification circuit is connected to the underwater acoustic emission transducer, the power conversion circuit realizes power voltage conversion, and the output voltage is used to power the wireless transceiver, the embedded CPU and its peripheral circuit and the power amplification circuit; the acoustic emission module is used to receive instructions from a remote control terminal through the wireless transceiver, complete channel coding, modulation of the remote control instructions and emission of underwater acoustic signals and the like;

[0007] The hardware system of the acoustic emission module comprises a wireless transceiver, an embedded CPU and its peripheral circuit, a power amplification circuit, a power conversion circuit and a underwater acoustic emission transducer, the wireless transceiver communicates with the embedded CPU through an RS232 serial port, digital signals generated by the embedded CPU are output to the power amplification circuit after D / A conversion, the output of the power amplification circuit is connected to the underwater acoustic emission transducer, the power conversion circuit realizes power voltage conversion, and the output voltage is used to power the wireless transceiver, the embedded CPU and its peripheral circuit and the power amplification circuit; the acoustic emission module is used to receive instructions from a remote control terminal through the wireless transceiver, complete channel coding, modulation of the remote control instructions and emission of underwater acoustic signals and the like;

[0008] The hardware system of the remote control terminal comprises a control panel, a single-chip microcomputer and a wireless transceiver; the remote control terminal receives user instructions through the remote control panel, source encodes the user instructions, and sends the encoded data to the acoustic emission module through the wireless transceiver. The single-chip microcomputer and the wireless transceiver communicate through an RS232 serial port.

[0009] An acoustic remote control method of a bionic robotic fish, comprising the following steps:

[0010] 1) The remote control terminal receives user input instructions through the control panel, and source encodes the user instructions;

[0011] 2) The remote control terminal sends the source encoded data obtained in step 1) to the acoustic emission module through the wireless transceiver;

[0012] 3) The acoustic emission module receives the user instruction from the remote terminal through the wireless transceiver, and returns the corresponding response to the remote terminal according to whether the user instruction is correct or not. The "Ok" response is returned if the user instruction is correct, and the "Err" response is returned if the user instruction is incorrect.

[0013] 4) The acoustic emission module (7, 4) Hamming encodes the user instruction data obtained in step 3) in groups of 4 bits.

[0014] 5) The acoustic emission module Pulse Position Modulation (PPM) encodes the encoded data obtained in step 4), in which 16PPM modulation is performed on the information bits in groups of 4 bits, and the linear frequency modulation pulse signal of the B1 sub-band is used; 8PPM modulation is performed on the check bits in groups of 3 bits, and the linear frequency modulation pulse of the B2 sub-band is used. The output signal after modulation is:

[0015]

[0016] wherein, N p = T p F s is the number of sampling points of the modulation pulse, T p is the pulse length, F s is the sampling frequency; I = N / 4, N is the length of the user instruction data to be sent; is the number of sampling points corresponding to the symbol period of the information bits; is the number of sampling points corresponding to the symbol period of the check bits; k i1 is the transmission symbol corresponding to the i-th group of data information bits; k i2 is the transmission symbol corresponding to the i-th group of data check bits; p i (n) is the linear frequency modulation signal with pulse width N p , that is:

[0017]

[0018] wherein, f i = f1, f i = f2 when i is odd, f1 and f2 are the start and end frequencies of the B1 and B2 sub-bands respectively when i is even.

[0019] 6) The acoustic emission module inserts a full-bandwidth detection signal identical to each frame of the modulated signal before and after the modulated signal, and inserts a protection interval between the detection signal and the modulated signal.

[0020] 7) The acoustic emission module converts the digital signal obtained in step 6) into an analog signal through a D / A converter, and the analog signal excites the underwater acoustic emission transducer to emit sound waves after power amplification.

[0021] 8) The hydrophone of the acoustic receiving module receives the acoustic signal from the acoustic transmitting module.

[0022] 9) The acoustic receiving module detects the signal obtained in step 8) to obtain the detection of the probe signal, and when the probe signal is detected, the time difference between the front and rear two probe signals is detected by the cross-correlation method, and the Doppler shift is estimated according to the time difference, and the received signal is compensated by Doppler.

[0023] 10) The acoustic receiving module uses the signal obtained in step 9) to obtain the estimated value of the impulse response of the underwater acoustic channel by the first probe signal That is,

[0024]

[0025] Wherein, is the estimated value of the number of paths of the underwater acoustic channel, and are the estimated values of the path amplitude and time delay of the underwater acoustic channel, respectively.

[0026] 11) The acoustic receiving module divides the signal obtained in step 9) into two paths, and performs band-pass filtering processing of B1 sub-band on the first path signal, and performs band-pass filtering processing of B2 sub-band on the second path signal.

[0027] 12) The acoustic receiving module performs time reversal processing on the two signals obtained in step 11) respectively, and uses energy detection method to judge the received symbol, and the received symbol corresponding to the i(i=1,2…,I) group of data information bits is:

[0028]

[0029] Wherein, r1(n) is the first path signal in step 11); k i1 =0,1,…,15. The received symbol corresponding to the i(i=1,2…,I) group of data check bits is:

[0030]

[0031] Wherein, r2(n) is the second path signal in step 11); k i2 =0,1,…,7.

[0032] 13) The acoustic receiving processing module demodulates the information bits and check bits of the symbol obtained in step 12), and performs (7,3) Hamming decoding.

[0033] 14) The acoustic receiving processing module judges whether the user instruction obtained in step 13) is correct according to the coding rule, and if it is correct, it is sent to the control host of the bionic robotic fish through the RS232 serial port, otherwise no sending operation is performed.​

[0034] The advantages of the present application are as follows:

[0035] 1. The system device adopts modular structure design, combines acoustic communication with radio communication, and realizes remote real-time control of the underwater bionic robotic fish.

[0036] 2. The acoustic communication adopts pulse position modulation technology, and has small duty ratio and energy loss; information bits and check bits adopt different modulation modes, and adopt linear frequency modulation pulse signals belonging to different sub-bands, so that code interference caused by multi-path transmission of the underwater acoustic channel can be effectively eliminated; the acoustic receiver adopts time reversal and energy detection combination method for demodulation, so that the energy of the signals arriving along each path of the underwater acoustic channel can be fully utilized.

[0037] 3. The source coding and (7, 3) Hamming channel coding technology are adopted, so that the system has strong anti-burst error capability.

[0038] 4. The embedded design scheme is adopted, so that the hardware system has small size, low power consumption and low price; the software system is upgradeable, easy to debug and has strong maintainability. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a general block diagram of the bionic robotic fish acoustic remote control device.

[0040] Figure 2 It is a structure diagram of the acoustic emission module.

[0041] Figure 3 It is a structure diagram of the acoustic receiving module.

[0042] Figure 4 It is a structure diagram of the remote control terminal.

[0043] Figure 5 It is a program flow chart of the remote control terminal.

[0044] Figure 6 It is a program flow chart of the acoustic emission module.

[0045] Figure 7 It is a frame structure of the emission signal.

[0046] Figure 8 It is a signal processing flow chart.

[0047] Figure 9 It is a program flow chart of the acoustic receiving processing module. DETAILED DESCRIPTION

[0048] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0049] The acoustic remote control device of the bionic robotic fish is composed of an acoustic emission module, an acoustic receiving module and a control terminal, as shown in Figure 1 The remote control terminal receives user instruction input, source encodes it, and outputs the encoded data to the acoustic emission module in a wireless communication mode. The acoustic emission module outputs data to the acoustic receiving module in an acoustic communication mode. The acoustic emission module completes Hamming encoding and pulse modulation of data, and the acoustic receiving module completes synchronization, Doppler estimation and compensation, channel estimation, time reversal, demodulation and Hamming decoding of underwater acoustic signals. The acoustic emission module, as shown in Figure 2 includes a wireless transceiver, an STM32 embedded CPU, a D / A converter and an underwater acoustic emission transducer. The wireless transceiver communicates with the STM32 embedded CPU through an RS232 serial port. The D / A converter uses an STM32 on-chip 12-bit D / A output circuit. The underwater acoustic emission transducer uses a circular plate type longitudinal diameter coupled vibration piezoelectric ceramic transducer with a 6dB bandwidth of 35kHz-45kHz. Except for the emission transducer immersed in water, the rest of the acoustic emission module is exposed to the water surface. The acoustic receiving module, as shown in Figure 3 includes an underwater acoustic receiving transducer, a preamplification filter circuit, an A / D converter and an STM32 embedded CPU. The underwater acoustic receiving transducer uses the same circular plate type longitudinal diameter coupled vibration piezoelectric ceramic transducer as the underwater acoustic emission transducer. The A / D converter uses an STM32 on-chip 12-bit A / D output circuit. The STM32 embedded CPU outputs control instructions to the control host of the bionic robotic fish through an RS232 serial port. Figure 4 The remote control terminal, as shown in

[0050] includes a control panel, a 89C51 single-chip microcomputer and a wireless transceiver. The control panel receives user instruction input. The 89C51 single-chip microcomputer communicates with the wireless transceiver through an RS232 serial port.

[0051] Table I Control Command Encoding Rules

[0052] Instructions Stop Forward Left turn Right turn Float up Sink down Reserved Reserved Code word 0000 0011 0101 0110 1001 1010 1100 1111

[0053] The remote control terminal program processing flow is shown in Figure 5As shown, after system initialization, it is detected whether the command button is pressed or not. If it is pressed, the source coding is performed according to the rules of Table I. At a certain time, only one command button is accepted as being in the pressed state. If multiple command buttons are pressed simultaneously, all the command buttons are invalid. The user control command, i.e. the code word, is sent to the wireless transceiver through the serial port. The wireless transceiver sends it to the acoustic transmitting module. The acoustic transmitting module receives the user control command through the wireless transceiver. If it is a correct user control command, i.e. the received user control command conforms to the coding rules shown in Table I, an "Ok" response is returned. Otherwise, an "Err" response is returned. The "Ok" coding is 0x00, and the "Err" coding is 0xff. After receiving the "Ok" response, the control terminal program clears the current sending code word and performs the next command button detection. If no response is received or an "Err" response is received, a counter is started and the user control command is sent to the acoustic transmitting module again until the "Ok" response is received or the counter overflows. If the counter overflows, the fault warning light is lit to inform the user that the wireless transceiver communication is faulty. The user can extinguish the warning light through the "clear fault" button.

[0054] The acoustic transmitting module program processing flow is as shown in Figure 6 The program includes a main program and a serial port interrupt program. The serial port interrupt program reads the data received from the wireless transceiver and sends it to the serial port buffer. The main program first initializes the system software and hardware, and then starts processing the data in the serial port buffer. If the serial port buffer has data, the user instruction is parsed according to the communication protocol. If the user instruction is correct, i.e. the instruction conforms to the coding rules in Table I, an "Ok" response information is returned through the serial port, and the user instruction is (7,3) Hamming coded. The information bits after Hamming coding are modulated using 16PPM, i.e. one symbol contains 4 bits, and there are 16 positions. The check bits are modulated using 8PPM, i.e. one symbol contains 3 bits, and there are 8 positions. A same linear frequency modulation signal is inserted before and after the modulated signal to generate a signal. The signal is output through D / A conversion to excite the underwater acoustic transmitting transducer to emit sound waves. In order to eliminate the code interference caused by the multipath propagation of underwater acoustic channel, the linear frequency modulation pulse signal belonging to B1 subband is used for the information bit corresponding symbol, and the linear frequency modulation pulse signal of B2 subband is used for the check bit corresponding symbol. The modulated output signal is:

[0055] s(n) = p1(n - k1N p ) + p2[n - 16N p -k2N p ] (6)

[0056] Wherein, k1 (0≤k1≤15) is the sending symbol corresponding to the first code element, the coding rule of k1 is shown in Table II, i.e. k1=0 represents the corresponding sending bit is "0000", and k1=15 represents the corresponding sending bit is "1000"; k2 (0≤k2≤7) is the sending symbol corresponding to the second code element, the coding rule of k2 is shown in Table II, i.e. k2=0 represents the corresponding sending bit is "000", and k2=7 represents the corresponding sending bit is "100"; N p = T p F s = 288 is the number of sampling points of the modulated pulse.

[0057] Table II information bit symbol coding rule

[0058] ​ 0 1 2 3 4 5 6 7 Bits 0000 0001 0011 0010 0110 0111 0101 0100 ​ 8 9 10 11 12 13 14 15 Bits 1100 1101 1111 1110 1010 1011 1001 1000

[0059] Table III check bit symbol coding rule

[0060] <k2> 0 1 2 3 4 5 6 7 Bits 000 001 011 010 110 111 101 100

[0061] The signal emitted by the acoustic emitting module adopts the frame structure as shown in Figure 7 . Each frame includes 4 linear frequency modulation pulse signals, wherein the 1st and the 4th linear frequency modulation pulse signals are completely identical, the frequency range is 35kHz-45kHz, and the duration is 10ms; the frequency range of the 2nd linear frequency modulation signal is 35kHz-39kHz, and the duration is 3ms, which is used to modulate the Hamming coded information bit; the frequency range of the 3rd linear frequency modulation signal is 40kHz-45kHz, and the duration is 3ms, which is used to modulate the Hamming coded check bit. A 20ms protection interval is inserted between the 1st linear frequency modulation pulse signal and the modulated signal, and a 20ms protection interval is also inserted between the modulated signal and the 4th linear frequency modulation pulse signal. The code element period of the 1st code element is 48ms, and the code element period of the 2nd code element is 24ms, thus the total time length of each frame signal is 132ms.

[0062] The signal receiving and processing flow of the acoustic receiving and processing module is shown in Figure 8 . The received signal is first amplified by the low noise amplifier Figure 8It can be seen that the receiving processing module mainly includes the function modules of Doppler shift estimation and compensation, underwater acoustic channel estimation, band-pass filtering, time reversal and energy detection and Hamming decoding. Since the pulse energy detection method is used to make the decision of the received symbol, the frequency variation caused by Doppler shift has less influence on the symbol decision, but the expansion or compression of the signal caused by Doppler shift will affect the position of the pulse, thus affecting the accuracy of the symbol decision. The acoustic receiving processing module estimates and compensates the Doppler shift through the two probe signals inserted before and after the modulated signal. If the time difference between the two probe signals in the received signal is the same as that between the two probe signals in the transmitted signal, no Doppler shift occurs and no compensation is needed. If the time difference is different, the received signal is resampled according to the time difference expansion (or reduction) to complete the compensation of the Doppler shift. After the Doppler compensation of the received signal, the cross-correlation detection method is used to estimate the impulse response of the underwater acoustic channel That is,

[0063]

[0064] wherein, is the number of paths of the underwater acoustic channel, and are the amplitude and delay of the l path, respectively. Assuming that the received signal is r(n), the band-pass filtering of r(n) through the sub-band B1 and the sub-band B2 gives r1(n) and r2(n), respectively. The time reversal processing of r1(n) and r2(n) gives and The received symbol corresponding to the information bit is:

[0065]

[0066] wherein, 0≤k1≤15. The received symbol corresponding to the check bit is:

[0067]

[0068] wherein, 0≤k2≤7. After obtaining and , the corresponding information bit and check bit can be obtained according to Table II and Table III, and the user instruction can be obtained by (7, 4) Hamming decoding.

[0069] The program flow chart of the acoustic receiving processing module is shown in Figure 9 . The received signal is first Figure 9It can be seen that the acoustic receiving processing module program includes a main program and A / D interrupt service program and A / D terminal service program, and the received signal is saved to A / D cache. In order to reduce the number of interrupts and improve the data storage efficiency, a direct memory access mode is adopted, and after 64 A / D data are stored, a terminal interrupt is generated, and the 64 A / D data are stored into the A / D cache at one time in the interrupt service program. After the main program completes the initialization of hardware and software, the data in the A / D cache is processed. A cross-correlation detection method is used to determine whether a synchronization signal arrives, if yes, Doppler shift estimation and compensation, underwater acoustic channel estimation, band-pass filtering, time reversal, PPM demodulation and Hamming decoding are performed, and effective user instructions are sent to the bionic robotic fish through a serial port; if not, subsequent A / D data is processed.

Claims

1. A biomimetic robotic fish acoustic remote control device, characterized in that... It consists of three parts: an acoustic transmitting module, an acoustic receiving module, and a remote control terminal. The data from the remote control terminal is output to the acoustic transmitting module via wireless communication, and the data from the acoustic transmitting module is output to the acoustic receiving module via acoustic communication. The acoustic receiving module outputs control commands to the bionic robotic fish via an RS232 serial port. The hardware system of the acoustic transmission module includes a wireless transceiver, an embedded CPU and its peripheral circuits, a power amplifier circuit, a power conversion circuit, and an underwater acoustic transducer. The wireless transceiver communicates with the embedded CPU via an RS232 serial port. The digital signal generated by the embedded CPU is converted by a D / A converter and output to the power amplifier circuit. The output of the power amplifier circuit is connected to the underwater acoustic transducer. The power conversion circuit converts the power supply voltage and outputs the voltage to power the wireless transceiver, the embedded CPU and its peripheral circuits, and the power amplifier circuit. The acoustic transmission module is used to receive commands from the remote control terminal via the wireless transceiver and complete the channel coding, modulation, and transmission of the underwater acoustic signal for the remote control command. The hardware system of the acoustic receiving module includes an embedded CPU and its peripheral circuits, an amplification and filtering circuit, a power conversion circuit, and a receiving underwater acoustic transducer. The embedded CPU and its peripheral circuits, as well as the power conversion circuit, are identical to those in the acoustic transmitting module. The output of the receiving underwater acoustic transducer is connected to the amplification and filtering circuit. The output signal of the amplification and filtering circuit enters the embedded CPU through an A / D converter. The embedded CPU outputs control commands to the bionic robotic fish via an RS232 serial port. The acoustic receiving module receives underwater acoustic signals from the acoustic transmitting module through the receiving underwater acoustic transducer, performs synchronization, Doppler estimation and compensation, channel estimation, time reversal, demodulation, and channel decoding of the underwater acoustic signals, and sends the received correct remote control commands to the control host of the bionic robotic fish via the RS232 serial port. The bandwidth of the underwater acoustic transmitting transducer is divided into two sub-bands, B1 and B2. After the user command data is grouped using Hamming encoding, the information bits are sent through the B1 sub-band, and the check bits are sent through the B2 sub-band. The hardware system of the remote control terminal includes a control panel, a microcontroller, and a wireless transceiver; the remote control terminal receives user commands through the remote control panel, performs source encoding on the user commands, and sends the encoded data to the acoustic transmission module through the wireless transceiver; the microcontroller and the wireless transceiver communicate through an RS232 serial port. The bandwidth of the underwater acoustic transmitter is divided into two subbands, B1 and B2. User command data is encoded in groups of 4 bits using (7,3) Hamming encoding. After encoding, the information bits are sent in groups of 4 bits through the B1 subband, while the parity bits are sent in groups of 3 bits through the B2 subband.

2. An acoustic remote control method for a biomimetic robotic fish, characterized in that... The method of using the biomimetic robotic fish acoustic remote control device as described in claim 1 includes the following steps: 1) The remote control terminal receives user input commands through the control panel and performs source encoding on the user commands; 2) The remote control terminal sends the source-encoded data obtained in step 1) to the acoustic transmission module via a wireless transceiver; 3) The acoustic transmitting module receives user commands from the remote control terminal via a wireless transceiver and returns corresponding responses to the remote control terminal based on whether the user commands are correct or not. It returns an "Ok" response for correct commands and an "Err" response for incorrect commands. 4) The acoustic transmission module performs (7,4) Hamming encoding on the user command data obtained in step 3) in groups of 4 bits; 5) The acoustic emission module performs pulse position modulation on the encoded data obtained in step 4); 6) The acoustic emission module inserts an identical full-bandwidth probe signal before and after each frame of modulated signal, and inserts a guard interval between the probe signal and the modulated signal. 7) The acoustic emission module converts the digital signal obtained in step 6) into an analog signal through a D / A converter. The analog signal is then amplified to excite the underwater acoustic emission transducer to emit sound waves. 8) The acoustic receiving module receives acoustic signals from the acoustic transmitting module via an underwater acoustic transducer; 9) The acoustic receiving module detects the detection signal obtained in step 8). After the detection signal is detected, the time difference change between the two detection signals is detected by cross-correlation method, and the Doppler frequency shift is estimated accordingly. The received signal is then compensated for by Doppler. 10) The acoustic receiving module uses the signal obtained in step 9) to obtain an estimate of the impact response of the underwater acoustic channel through the first detection signal; 11) The acoustic receiving module splits the signal obtained in step 9) into two paths, performs bandpass filtering on the first path signal in the B1 subband, and performs bandpass filtering on the second path signal in the B2 subband. 12) The acoustic receiving module performs time reversal processing on the two signals obtained in step 11), and uses the energy detection method to make a decision on the received symbols; 13) The acoustic receiving and processing module demodulates the information bits and check bits of the symbols obtained in step 12) and performs (7,3) Hamming decoding; 14) The acoustic receiving and processing module determines whether the user instruction obtained in step 13) is correct according to the encoding rules. If it is correct, it sends it to the control host of the bionic robotic fish through the RS232 serial port; otherwise, it does not perform the sending operation.

3. The acoustic remote control method for a biomimetic robotic fish as described in claim 2, characterized in that... In step 5), the acoustic emission module performs pulse position modulation on the encoded data obtained in step 4). The information bits are modulated at 16 PPM in groups of 4 bits, using a linear frequency modulated pulse signal from the B1 subband. The parity bits are modulated at 8 PPM in groups of 3 bits, using a linear frequency modulated pulse from the B2 subband. The modulated output signal is: Where, N p =T p F s T represents the number of sampling points for the modulation pulse. p For pulse duration, F s The sampling frequency is I; I = N / 4, where N is the length of the user instruction data to be sent. The number of dots is used to represent the symbol period corresponding to the information bits; The number of sampling points in the symbol period corresponding to the check bit; k i1 k is the transmission symbol corresponding to the i-th group of data information bits; i2 p is the transmitted symbol corresponding to the i-th group of data check bits; i (n) represents the pulse width N. p The linear frequency modulated signal, i.e.: Among them, f i =f1, when i is odd, f i =f2, when i is even, f1 and f2 are the start and end frequencies of subbands B1 and B2, respectively.

4. The acoustic remote control method for a biomimetic robotic fish as described in claim 3, characterized in that... In step 10), the estimated value of the impulse response of the underwater acoustic channel is: in, This is an estimate of the underwater acoustic channel path number. and The underwater acoustic channel is the first Estimated values ​​for path amplitude and time delay.

5. The acoustic remote control method for a biomimetic robotic fish as described in claim 3, characterized in that... In step 12), the received symbol, the received symbol corresponding to the i-th (i = 1, 2, ..., I) group of data information bits is: Where r1(n) is the first signal in step 11); k i1 =0,1,…,15; the received symbol corresponding to the i-th (i=1,2,…,I) group of data parity bits is: Where r2(n) is the second signal in step 11); k i2 =0,1,…,7.

Images