An underwater robot positioning system and method

Abstract

The present invention discloses an underwater robot positioning system and method. The system includes: a guiding machine, an underwater robot main console signal-connected to the guiding machine, an underwater robot connected to the underwater robot main console through an umbilical cable, and a transponder disposed on the underwater robot. The transponder includes a transmitting transducer and a direction-finding transducer. The guiding machine is connected to a guiding transducer through a cable. The guiding transducer is located in water and is respectively signal-connected to the transmitting transducer and the direction-finding transducer. The system has two working modes: a synchronous mode and a response mode. The underwater robot is positioned through the synchronous mode, with strong anti-interference ability, which can effectively avoid the interference of reverberation on positioning and achieve accurate positioning. In the response mode, the underwater robot can accurately return, avoiding the loss of the position of the underwater robot after the umbilical cable breaks, resulting in difficulties or inability to return for the underwater robot.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater robot positioning, and particularly relates to a system and method for accurately positioning an underwater robot in a limited space with severe reverberation such as a water-filled tunnel. Background Art

[0002] Diversion-type hydropower stations are very common in hydropower stations in China. They use long-distance water conveyance tunnels to introduce high-head water bodies into generator sets for power generation, which are key hydraulic structure facilities of hydropower stations. Due to the influence of long-term operation or construction quality factors, the concrete lining of the water conveyance tunnel often has apparent defects such as concrete cracks, waterstop damage, concrete erosion, exposed reinforcement, erosion, surface attachments, and bottom plate wear, which will further lead to lining collapse and spalling, lining deformation, concrete cracking, and internal defects, and seriously will cause major accidents. At present, the underwater robot operation technology has been continuously promoted and applied in the field of inspection of underwater engineering structures of hydropower stations. However, reliably and accurately positioning the underwater robot in a long water-filled tunnel, realizing the control of the operation situation, and positioning and recording the location of structural defects are one of the key technologies that need to be solved in the development of underwater robot operation technology in the field of hydropower and hydraulic inspection.

[0003] When the underwater robot operates in a closed water-filled tunnel for a long time, it is necessary to real-time monitor the underwater orientation of the underwater robot and use it to indirectly determine the location of the tunnel structural defects when there is a lack of position reference in the tunnel. Currently, the most commonly used positioning technologies for underwater robots are mainly underwater acoustic positioning, GPS-based and inertial navigation technologies, and underwater vision positioning.

[0004] It is difficult to obtain satellite signals in a closed underwater tunnel space through the navigation and positioning method based on GPS and inertial navigation technologies, and the error of the inertial navigation device will continuously accumulate during long-term operation, so it cannot provide reliable and effective positioning.

[0005] Underwater vision positioning is to take pictures through a camera and perform positioning in combination with image processing algorithms. Due to the low visibility in the tunnel, the image quality taken by the camera is poor, and there are no obvious structural difference features on the underwater concrete lining, so it is impossible to position the underwater robot through this method.

[0006] Underwater acoustic positioning is a technology for determining the orientation and distance of an underwater vehicle or device with an underwater acoustic device. Positioning is performed according to the arrival time or phase of the acoustic pulse signals received from more than three acoustic transponders that make up the array. However, due to the relatively severe reverberation in the tunnel and being limited by the structural size of the underwater vehicle, there are factors such as difficult operation, placement, and installation, and the existing underwater acoustic positioning methods cannot achieve the positioning of the underwater robot. Summary of the Invention

[0007] In view of the above problems, the inventors provide an underwater robot positioning system and method, which can accurately position an underwater robot in a limited space with severe reverberation such as a water-filled tunnel.

[0008] According to the first aspect, the present invention provides an underwater robot positioning system, including a guiding machine, an underwater robot main control console signal-connected to the guiding machine, an underwater robot connected to the underwater robot main control console through an umbilical cable, and a transponder arranged on the underwater robot. The transponder includes a transmitting transducer and a direction-finding transducer. The guiding machine is connected to a guiding transducer through a cable. The guiding transducer is located in water, and the guiding transducer is signal-connected to the transmitting transducer and the direction-finding transducer through underwater sound. When the umbilical cable is intact, the system is in a synchronous mode. When the umbilical cable is broken, the system switches to a response mode.

[0009] Further, the guiding machine includes: a single-chip microcomputer, a signal generation circuit connected to the single-chip microcomputer, and a signal conditioning circuit. The single-chip microcomputer is signal-connected to the underwater robot main control console, and both the signal generation circuit and the signal conditioning circuit are signal-connected to the guiding transducer.

[0010] According to the second aspect, the present invention also provides an underwater robot positioning method, including: a guiding machine, an underwater robot main control console signal-connected to the guiding machine, an underwater robot connected to the underwater robot main control console through an umbilical cable, and a transponder arranged on the underwater robot. The transponder includes a transmitting transducer and a direction-finding transducer. The guiding machine is connected to a guiding transducer through a cable. The guiding transducer is located in water, and the guiding transducer is signal-connected to the transmitting transducer and the direction-finding transducer. The method includes: a synchronous mode and a response mode, wherein the synchronous mode includes:

[0011] The guiding machine sends a synchronous pulse emission instruction to the underwater robot through the underwater robot main control console at a set period and starts timing;

[0012] The underwater robot receives the synchronous pulse emission instruction and transmits the synchronous pulse emission instruction to the transmitting transducer;

[0013] After receiving the synchronous pulse emission instruction, the transmitting transducer emits a synchronous pulse sound signal;

[0014] The guiding machine receives the synchronous pulse sound signal through the guiding transducer and stops timing;

[0015] Determine the distance between the underwater robot and the guiding transducer according to the time difference between the guiding machine sending the synchronous pulse emission instruction and receiving the synchronous pulse sound signal;

[0016] When the umbilical cable breaks, the underwater robot sends a response mode instruction to the transponder, and the transponder switches to the response mode. The response mode includes:

[0017] The guiding transducer continuously emits omnidirectional pulsed sound signals according to the instructions of the guiding machine;

[0018] The direction-finding transducer receives the pulsed sound signal emitted by the guiding transducer and sends the pulsed sound signal to the transponder;

[0019] The transponder determines the incident direction of the pulsed sound signal according to the pulsed sound signal and sends the incident direction to the underwater robot;

[0020] The underwater robot returns along the incident direction.

[0021] Further, the distance D between the underwater robot and the guiding transducer is D = C×(T - t)

[0022] where C is the propagation speed of sound in water; T is the time difference between the guiding machine sending the synchronous pulse emission instruction and receiving the synchronous pulsed sound signal; t is the time delay from the guiding machine sending the synchronous pulse emission instruction to the transmitting transducer sending the synchronous pulsed sound signal.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The underwater robot positioning system and method provided by the present invention have two working modes: synchronous mode and response mode. The underwater robot is positioned through the synchronous mode, with strong anti-interference ability, which can effectively avoid the interference of reverberation on positioning and achieve accurate positioning. In the response mode, the underwater robot can accurately return, avoiding the loss of the position of the underwater robot after the umbilical cable breaks, resulting in difficulties or inability to return for the underwater robot.

[0025] (2) The transponder has the characteristics of being light in structure, easy to install, and having low requirements for the load of the underwater robot, and is easy to implement; its guiding transducer has the remarkable characteristics of small volume, light weight, convenient to carry at the operation site, simple to deploy, and does not require fixed installation.

[0026] (3) The underwater robot positioning system and method provided by the present invention get rid of the dependence on GPS signals based on GPS and inertial navigation technologies in a highly enclosed water-filled tunnel environment, and can achieve reliable positioning in underwater turbid and low-light environments. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the underwater robot positioning system in Embodiment 1;

[0028] Figure 2Schematic diagram of the principle of the guiding machine in Embodiment 1;

[0029] Figure 3 Schematic diagram of the principle of the transponder in Embodiment 1;

[0030] Figure 4 Schematic diagram of the working principle of the synchronization mode of the underwater robot positioning system in Embodiment 1;

[0031] Figure 5 Schematic diagram of the working principle of the response mode of the underwater robot positioning system in Embodiment 1.

[0032] Reference numerals:

[0033] 1 - Guiding machine; 11 - Guiding transducer; 2 - Main control console of the underwater robot; 3 - Umbilical cable; 4 - Underwater robot; 5 - Transponder; 51 - Transmitting transducer; 52 - Direction-finding transducer. Detailed implementation manners

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings through specific implementation manners.

[0035] Embodiment 1

[0036] The present invention provides an underwater robot positioning system, which can accurately position an underwater robot in a limited space with severe reverberation such as a water-filled tunnel. Specifically, as Figure 1 shown, the positioning system includes: a guiding machine 1 placed on the shore or on a ship, a main control console 2 of the underwater robot signal-connected to the guiding machine, an underwater robot 4 connected to the main control console 2 of the underwater robot through an umbilical cable 3, and a transponder 5 arranged on the underwater robot 4. The guiding machine 1 is connected to the guiding transducer 11 through a signal transmission cable, and the guiding transducer 11 is lowered into the water for transmitting or receiving acoustic pulse signals. As Figure 2 shown, the guiding machine 1 is composed of a single-chip microcomputer, a signal generation circuit, a power amplification circuit, a signal conditioning circuit, an A / D acquisition circuit on the single-chip microcomputer, and connectors arranged in the main chassis of the guiding machine. The single-chip microcomputer is respectively connected to the main control console 2 of the underwater robot and a display and control computer through serial ports, and is connected to the guiding transducer 11 through connectors and a signal transmission cable.

[0037] As Figure 3 shown, the transponder 5 is composed of a transmitting transducer 51, a signal generation circuit connected to the transmitting transducer 51, a power amplification circuit, a direction-finding transducer 52, a preamplifier connected to the direction-finding transducer, a signal conditioning circuit, an A / D circuit, and a DSP circuit (digital signal processing circuit). The DSP circuit is connected to the underwater robot 4 through a serial port.

[0038] Specifically, as Figure 4As shown, under normal circumstances (when the umbilical cable 3 is intact), the system locates the underwater robot 4 in the default working mode (synchronous mode):

[0039] The single-chip microcomputer of the guidance machine 1 sends a synchronous pulse emission instruction to the main console 2 of the underwater robot through the serial port according to the set period and starts timing. The main console 2 of the underwater robot sends this instruction to the underwater robot 4 through the umbilical cable 3, and the underwater robot 4 then transmits it to the transponder 5. The signal generation circuit on the transponder 5 generates a corresponding electrical signal, which is amplified by the power amplifier and then converted into a synchronous pulse sound signal by the transmitting transducer 51 and sent to the guiding transducer 11. After receiving this signal, the guiding transducer 11 converts it into a corresponding electrical signal, which is transformed into a digital signal that can be collected by the single-chip microcomputer A / D circuit through the signal conditioning circuit and then transmitted to the single-chip microcomputer. When the guiding transducer 11 receives the synchronous pulse sound signal, the single-chip microcomputer stops timing and records the time difference T of the process from sending the synchronous pulse emission instruction to receiving the synchronous pulse sound signal, and calculates the distance D between the underwater robot and the guiding transducer as D = C×(T - t), where C is the sound propagation speed in water, usually 1500 m / s, and in actual use, it can be set according to the actual situation. For example, in seawater at 25°C, C = 1531 m / s. t is the time delay from when the guidance machine sends the synchronous pulse emission instruction to when the transmitting transducer 51 sends the synchronous pulse sound signal. The calculation result of the distance between the underwater robot 4 and the guiding transducer 11 can be transmitted to the display and control computer through the serial port for display.

[0040] However, when the umbilical cable 3 breaks, the main console 2 of the underwater robot is disconnected from the underwater robot 4. At this time, the underwater robot 4 sends an instruction to switch to the response mode to the transponder 5 through the serial port. After receiving this instruction, the transponder 5 switches to the response mode. In this mode, the underwater robot 4 returns to base according to the position of the guiding transducer 11, as Figure 5 shown, specifically:

[0041] The signal generation circuit of the guidance machine 1 generates an electrical signal, which is amplified by the power amplification circuit and then transmitted to the guiding transducer 11. The guiding transducer 11 converts this electrical signal into an omnidirectional guiding pulse sound signal. The direction-finding transducer 52 composed of multiple highly directional receiving transducers receives the pulse sound signals from different directions. Since the intensity ratios of the signals received by different receiving transducers are different, by comparing the signal intensity ratios with the look-up table, the specific incident direction of the guiding pulse sound signal (i.e., the azimuth of the guiding transducer 11) can be queried, and the underwater robot 4 returns to base according to the incident direction.

[0042] Specifically, the method for making the look-up table is as follows:

[0043] In the anechoic tank, calibrate the received signal intensity ratio corresponding to each incident direction within the horizontal 360° range at a resolution of 1°. After calibration, obtain the intensity ratio of the received signal of the receiving transducer in each incident direction, and record the intensity ratio of the signal in each incident direction.

[0044] The above uses specific examples to elaborate on the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the technical field to which the present invention pertains, based on the idea of the present invention, several simple deductions, deformations or substitutions can also be made.

Claims

1. An underwater robot positioning system, characterized in that, it includes a guiding machine, an underwater robot main console signal - connected to the guiding machine, an underwater robot connected to the underwater robot main console through an umbilical cable, and a transponder arranged on the underwater robot. The transponder includes a transmitting transducer and a direction - finding transducer. The guiding machine is connected to a guiding transducer through a cable. The guiding transducer is located in water and is communicatively connected to the transmitting transducer and the direction - finding transducer respectively. When the umbilical cable is intact, the system is in a synchronous mode. When the umbilical cable breaks, the system switches to a response mode; The synchronous mode includes: The guiding machine sends a synchronous pulse emission instruction to the underwater robot through the underwater robot main console at a set period and starts timing; The underwater robot receives the synchronous pulse emission instruction and transmits the synchronous pulse emission instruction to the transmitting transducer; After receiving the synchronous pulse emission instruction, the transmitting transducer emits a synchronous pulse sound signal; The guiding machine receives the synchronous pulse sound signal through the guiding transducer and stops timing; Determine the distance between the underwater robot and the guiding transducer according to the time difference between the guiding machine sending the synchronous pulse emission instruction and receiving the synchronous pulse sound signal; When the umbilical cable breaks, the underwater robot sends a response mode instruction to the transponder, and the transponder switches to the response mode; The response mode includes: The guiding transducer continuously emits an omnidirectional pulse sound signal according to the instruction of the guiding machine; The direction - finding transducer receives the pulse sound signal emitted by the guiding transducer and sends the pulse sound signal to the transponder; The transponder determines the incident direction of the pulse sound signal according to the pulse sound signal and sends the incident direction to the underwater robot; The underwater robot returns along the incident direction.

2. The underwater robot positioning system according to claim 1, characterized in that, the guiding machine includes: a single - chip microcomputer, a signal generation circuit connected to the single - chip microcomputer, and a signal conditioning circuit. The single - chip microcomputer is signal - connected to the underwater robot main console, and both the signal generation circuit and the signal conditioning circuit are signal - connected to the guiding transducer.

3. The system according to claim 1, characterized in that, the distance D between the underwater robot and the guiding transducer is D = C×(T - t) where C is the propagation speed of sound in water; T is the time difference between the guiding machine sending the synchronous pulse emission instruction and receiving the synchronous pulse sound signal; t is the time delay from the guiding machine sending the synchronous pulse emission instruction to the transmitting transducer emitting the synchronous pulse sound signal.

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