CN115783166A - Head-dropping-free underwater cleaning robot and control method thereof - Google Patents

Abstract

The invention relates to a head-dropping-free underwater cleaning robot and a control method thereof. The main frame is a double-layer pipe structure, the propelling and adsorbing assembly consists of a plurality of horizontal propellers and vertical propellers, the walking and steering assembly consists of universal wheels and bearing wheels driven by steering gears, the sensing and controlling assembly comprises a pressure sensor, a Doppler velocimeter, an attitude sensor and a hydroacoustic locator, and the cavitation cleaning device is a plurality of cavitation jet cleaning disks. The cleaning robot is mainly used for underwater cleaning of large-scale structural surface attachments such as ships, ports and wharfs, and the steering engine is adopted to drive the wheels to turn, move transversely and turn around, so that the control difficulty can be reduced, the maneuverability is increased, the turn-around time and space are saved, and the control precision, the cleaning efficiency and the single cleaning coverage rate are improved.

Description

Head-dropping-free underwater cleaning robot and control method thereof

Technical Field

The invention belongs to the technical field of large-scale structure surface underwater cleaning robots, and particularly relates to a head-dropping-free underwater cleaning robot and a control method thereof.

Background

A large amount of seashells, seaweeds, barnacles and other marine organisms can be attached to the surfaces of hull shells, ports, wharf facades and the like which are soaked in seawater for a long time, so that the speed, the oil consumption, the controllability and the like of ships are influenced, the corrosion degree of attached walls is aggravated, and the service life is influenced. Therefore, frequent or regular cleaning is required from the viewpoints of economy, environmental protection, safety, reliability, and the like.

Compared with the traditional manual cleaning mode, the underwater robot cleaning mode has the advantages of economy, safety, high efficiency and the like, and related cleaning robot products are actively researched and developed at home and abroad, and certain achievements are obtained. However, in the related large cleaning robot patents or products disclosed at present, when cleaning large wall surfaces, the robot basically turns around after turning around, and the large underwater robot has a large turning around radius, long turning time and large control difficulty, so that the working efficiency is greatly reduced by the turning around mode.

Disclosure of Invention

In order to overcome the defects of the existing underwater cleaning robot turning method and solve the problems of low turning operation efficiency, high control difficulty, low control precision and easiness in washing leakage of a large underwater cleaning robot, a solution is provided.

The invention provides a head-dropping-free underwater cleaning robot, which comprises a main frame 1, a propelling and adsorbing assembly 2, a walking and steering assembly 3, a sealed electronic cabin 4, a sensing control assembly 5, an optical communication device 6, a buoyancy module 7 and a cavitation cleaning device 8, wherein the propelling and adsorbing assembly is arranged on the main frame; wherein:

the propelling and adsorbing assembly 2 comprises a plurality of vertical propellers 21 and a plurality of horizontal propellers 22, and the vertical propellers 21 provide rolling moment and adherence adsorption force for the robot; the horizontal thruster 22 provides driving force for the robot to walk around and walk along the wall;

the walking and steering assembly 3 comprises a first bearing wheel 31, a second bearing wheel 32, a third bearing wheel 33, a first steering engine 34 and a second steering engine 35; the first bearing wheel 31 is driven by the first steering engine 34 to turn and fix the direction, and the second bearing wheel 32 is driven by the second steering engine 35 to turn and fix the direction; the third bearing wheels 33 are universal wheels;

the sealed electronic cabin 4 comprises a robot power supply device, a control device and an information transmission device;

the sensing control component 5 comprises a pressure sensor 51, a doppler velocity meter 52, a hydroacoustic locator 53 and a posture sensor, wherein the pressure sensor 51 provides depth information of the robot, the doppler velocity meter 52 provides the moving speed of the robot, the hydroacoustic locator 53 provides position information of the robot, and the posture sensor provides current posture information of the robot;

the light flux equipment 6 comprises a camera 61 and an illuminating lamp 62 which are simultaneously arranged in the middle of the front end and the rear end of the main frame 1 and are used for illuminating, recording and observing the environment in front of and behind the robot;

the buoyancy module 7 consists of a plurality of sealed thin-wall shells, and is arranged at the front part, the middle part and the rear part of the main frame 1 in a bilateral symmetry manner;

the cavitation cleaning device 8 is composed of three cavitation jet cleaning discs and is arranged in the middle of the main frame 1.

Furthermore, in the head-dropping-free underwater cleaning robot, the main frame 1 is a double-layer sealing frame structure formed by connecting pipes, and can provide buoyancy far larger than self weight.

Furthermore, in the head-dropping-free underwater cleaning robot, the first bearing wheel 31, the second bearing wheel 32 and the third bearing wheel 33 are driven wheels, are arranged on the lower side of the main frame 1 in an isosceles triangle shape, and are pushed to move by the horizontal thruster 22.

Furthermore, the first steering engine 34 and the second steering engine 35 in the head-dropping-free underwater cleaning robot can rotate for 360 degrees and can be self-locked after reaching a target angle; position sensors are arranged in the first steering engine 34 and the second steering engine 35 and used for feeding back rotation angle information so as to realize steering closed-loop controllability.

Secondly, the invention also provides a control method of the turning-free underwater cleaning robot, which comprises the following steps:

(1) Controlling a plurality of horizontal thrusters 22 to push the robot to walk on the operation wall surface in a straight line;

(2) When the robot reaches the edge of the operation wall surface, the first steering engine 34 and the second steering engine 35 are controlled to synchronously rotate for 90 degrees, and the first bearing wheel 31 and the second bearing wheel 32 are driven to rotate for 90 degrees;

(3) Then controlling a plurality of horizontal thrusters 22 to push the robot to transversely move for one station width, and then controlling a first steering engine 34 and a second steering engine 35 to drive a first bearing wheel 31 and a second bearing wheel 32 to rotate for 90 degrees;

(4) And finally, controlling a plurality of horizontal thrusters 22 to push the robot to walk linearly in opposite directions, so as to realize the bow-shaped operation without turning around.

Further, in the control method of the u-turn free underwater cleaning robot, when the robot travels straight on the working wall surface, closed-loop control is performed according to data collected by the pressure sensor 51, the doppler velocity meter 52 and the attitude sensor, and the rotation speeds and the steering of the plurality of horizontal thrusters 22 are respectively controlled, so that the robot travels straight ahead at a certain speed.

Further, in the control method of the u-turn-free underwater cleaning robot, when the robot travels straight on the operation wall surface, the controlled variables are the pitch angle, the depth and the traveling speed of the robot, and the control method includes:

(1) Firstly, setting an expected pitch angle to be zero, and issuing an expected depth and an expected walking speed by an upper computer;

(2) Secondly, constructing errors of the pitch angle, the depth and the walking speed on the basis of acquiring the pitch angle, the depth and the walking speed of the robot by using an attitude sensor, a pressure sensor 51 and a Doppler velocity meter 52;

(3) Thirdly, according to the spatial layout of the horizontal thruster 22, mapping relations between the thrust of the horizontal thruster 22 and the transverse resultant force, and between the pitching moment and the forward resultant force are established;

(4) And finally, constructing a mapping relation between the thrust of the horizontal thruster 22 and the errors of the pitch angle, the depth and the walking speed by utilizing a PID control strategy, namely a control law.

Further, in the control method of the u-turn-free underwater cleaning robot, the first steering engine 34 and the second steering engine 35 are controlled to drive the first bearing wheel 31 and the second bearing wheel 32 to rotate by 90 degrees, and the control method comprises the following steps:

(1) Firstly, controlling a horizontal thruster 22 to adjust the posture of the robot so that the pitch angle error of the robot reaches a desired value;

(2) Secondly, issuing an expected steering engine turning angle by an upper computer;

(3) Thirdly, acquiring the rotation angles of the two steering engines by using position sensors arranged in the first steering engine 34 and the second steering engine 35, and constructing steering engine rotation angle errors;

(4) And finally, performing corner closed-loop correction based on the steering engine position control mode to enable the steering engine corner error to reach an expected value.

Further, in the control method of the u-turn-free underwater cleaning robot, when the robot moves transversely, closed-loop control is performed according to data collected by the pressure sensor 51, the doppler velocity meter 52, the underwater acoustic positioner 53 and the attitude sensor, the rotation speeds and the steering directions of the plurality of horizontal thrusters 22 are respectively controlled, and the robot is controlled to move transversely by one station width.

Further, in the control method of the u-turn-free underwater cleaning robot, when the robot moves laterally, the controlled variables are the traversing distance and the pitch angle of the robot, and the control method includes:

(1) Firstly, setting an expected traversing distance and an expected pitch angle as a station width and zero of the robot respectively;

(2) Secondly, constructing a sideslip distance and pitch angle error on the basis of acquiring the sideslip amount, depth difference, pitch angle and roll angle of the robot by using the Doppler velocity instrument 52, the pressure sensor 51, the underwater acoustic locator 53 and the attitude sensor;

(3) Thirdly, according to the spatial layout of the horizontal thruster 22, constructing a mapping relation between the thrust of the horizontal thruster 22 and the transverse resultant force and the pitching moment;

(4) And finally, constructing a mapping relation between the thrust of the horizontal thruster 22 and the errors of the traversing distance and the pitching angle by utilizing a PID control strategy, namely a control law.

Compared with the prior art, the invention has the beneficial effects that:

1) The invention adopts a mode that the horizontal propeller pushes the wheels to walk, has simple structure and can avoid the phenomenon of skidding of the wheels.

2) The steering engine is adopted to drive the wheels to steer, move transversely and steer to replace turning around, so that the control difficulty can be reduced, the maneuverability is increased, the turning around time and space are saved, and the cleaning efficiency and the single cleaning coverage rate of the robot are improved.

3) The steering engine-bearing wheel combination provided by the invention is fixed in direction when the robot walks in a straight line and can rotate to any specified angle when the robot needs to turn, so that the walking straightness and the steering flexibility of the robot are improved.

4) The control method provided by the invention integrates various sensor information, is oriented to the control strategy constructed by the operation mode of the head-dropping-free cleaning robot, and has high control precision and good control stability.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below. It is to be understood that the drawings in the following description are illustrative of some, but not all embodiments of the invention, and that other drawings may be derived therefrom by those skilled in the art without the benefit of the teachings herein.

Fig. 1 is a general diagram of an underwater cleaning robot provided in an embodiment of the present invention.

Fig. 2 is a top view of an underwater cleaning robot provided in an embodiment of the present invention.

Fig. 3 is a bottom view of an underwater cleaning robot provided in an embodiment of the present invention.

Fig. 4 is a combined view of a steering engine and a bearing wheel according to an embodiment of the present invention.

Fig. 5 is a schematic view of the direction of wheels when the underwater cleaning robot provided by the embodiment of the present invention moves transversely.

Fig. 6 is a flowchart illustrating an operation of the underwater cleaning robot according to the embodiment of the present invention.

Reference numerals: 1: a main frame; 2: a propulsion and adsorption assembly; 3: a walking and steering assembly; 4: sealing the electronic cabin; 5: a sensing control component; 6: a light pass device; 7: a buoyancy module; 8: a cavitation cleaning device; 21: a vertical thruster; 22: a horizontal thruster; 31: a first load-bearing wheel; 32: a second bearing wheel; 33: a third load-bearing wheel (universal wheel); 34: a first steering engine; 35: a second steering engine; 51: a pressure sensor; 52: a Doppler velocimeter; 53: an acoustic locator; 61: a camera; 62: an illuminating lamp.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. It is to be understood that the embodiments described are merely illustrative of some, but not all, of the present invention and that the invention may be embodied or carried out in various other specific forms, and that various modifications and changes in the details of the specification may be made without departing from the spirit of the invention.

Also, it should be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Example 1: the invention relates to a no-head-dropping underwater cleaning robot, and the embodiment of the invention is explained in detail below with reference to the attached drawings 1-5.

Referring to fig. 1, 2 and 3, the turning-around-free underwater cleaning robot comprises a main frame 1, a propelling and adsorbing assembly 2, a walking and steering assembly 3, a sealed electronic cabin 4, a sensing control assembly 5, a light-passing device 6, a buoyancy module 7 and a cavitation cleaning device 8.

The propulsion and adsorption assembly 2 comprises a plurality of vertical propellers 21 and a plurality of horizontal propellers 22, in the embodiment, four vertical propellers and four horizontal propellers are respectively arranged, and the arrangement of the vertical propellers ensures that at least the sinking, floating, pitching and rolling motions of the underwater robot in the tour process can be controlled and realized and the adsorption force required by the underwater robot to work on the operation surface is provided; the arrangement of the horizontal propeller needs to ensure that the forward and backward and yaw movement of the tour process of the underwater robot and the forward, backward and transverse movement of the underwater robot when the underwater robot works against the wall can be controlled at least.

As shown in fig. 2 and 3, the walking and steering assembly 3 includes a first bearing wheel 31, a second bearing wheel 32, a third bearing wheel 33, a first steering engine 34 and a second steering engine 35; the bearings of the three bearing wheels are hermetically designed so as to avoid the blockage and even the death caused by salt accumulation, corrosion and the like after long-time work in seawater; the three bearing wheels are driven wheels, are fixedly arranged on the lower side of the main frame 1 in an isosceles triangle shape, and are pushed to move by four horizontal thrusters 22.

As shown in fig. 4, the output shaft of the first steering engine 34 drives the first bearing wheel 31 to steer through key connection, and when the target angle is reached, the first steering engine 34 is self-locked and fixes the direction of the first bearing wheel 31; an output shaft of the second steering engine 35 is in key connection with the second bearing wheel 32 to drive the second bearing wheel to turn, and after the target angle is reached, the second steering engine 35 is self-locked and fixes the direction of the second bearing wheel 32; the first steering engine 34 and the second steering engine 35 can rotate 360 degrees, position sensors are installed in the steering engines, and rotation angle information can be fed back to achieve steering closed-loop controllability.

As shown in figure 2, the sealed electronic cabin 4 is arranged at the middle position near the front end of the main frame 1 along the length direction of the main frame 1, and all non-waterproof equipment for robot power supply, control and information transmission is integrated in the sealed electronic cabin, and a watertight connector is adopted as an external wiring port.

As shown in fig. 2 and 3, the sensing and control assembly 5 includes a pressure sensor 51, a doppler velocity meter 52, a hydrophone 53, and an attitude sensor; the pressure sensor 51 is arranged at the transverse center line position of the robot and provides depth information of the robot in underwater operation; the Doppler velocimeter 52 is arranged in the main frame 1 through a bracket and provides the moving speed of the robot; the underwater positioner 53 is arranged on the frame of the main frame 1 and provides the position information of the robot; the attitude sensor is arranged in the sealed electronic cabin 4 and provides attitude information such as a pitch angle, a roll angle and the like in the motion process of the robot.

As shown in fig. 2 and 3, the light passing device 6 includes a camera 61 and an illumination lamp 62, and one camera 61 is installed at each of the lower front and rear middle portions of the main frame 1; a set of illuminating lamps 62 are respectively arranged in the middle of the front end and the rear end of the upper layer of the main frame 1; the brightness of the illuminating lamp is adjustable, underwater illumination and light supplement are carried out on the camera, and therefore environmental information on the front and the back of the robot can be shot, recorded and observed clearly.

As shown in fig. 1, the main frame 1 is a double-layer frame structure formed by connecting pipes, the volume density of the pipes is less than that of water, and the whole frame is fully sealed and can provide buoyancy far greater than the dead weight.

As shown in fig. 1 and 2, the buoyancy module 7 is composed of a plurality of sealed thin-wall shells, which may be cylindrical cylinders, spherical shells, etc., and in the embodiment of the present invention, a plurality of cylindrical cylinders are used as the buoyancy cylinders and are arranged at the front, middle and rear portions of the main frame 1 in a left-right symmetrical manner; the buoyancy cylinder is simple in structure, small in specific gravity and low in cost, the situation that the density of the glass bead buoyancy material changes after being soaked in water for a long time is avoided, and the buoyancy cylinder has great advantages for underwater robots for shallow water operation.

As shown in fig. 2, the cavitation cleaning device 8 is composed of three cavitation jet cleaning discs, the three cavitation jet cleaning discs are arranged in a triangle, and the lower edge of each cavitation jet cleaning disc is supported by three universal wheels; the cavitation cleaning device 8 is arranged in the middle of the main frame 1, and when the robot walks, the robot drives the three cavitation jet cleaning discs to move along the wall, so that the robot walks and cleans the wall surface at the same time.

The method for avoiding the head dropping operation of the head dropping-free underwater cleaning robot comprises the following main steps: firstly, controlling four horizontal thrusters 22 to push the robot to walk on the operation wall surface in a straight line, controlling two steering engines (a first steering engine 34 and a second steering engine 35) to synchronously rotate 90 degrees when the robot reaches the edge of the wall surface, driving a first bearing wheel 31 and a second bearing wheel 32 to rotate 90 degrees, then controlling the four horizontal thrusters 22 to push the robot to move transversely, and automatically rotating the third bearing wheel 33 90 degrees along the stress direction at the moment, wherein the directions of the three bearing wheels are shown in figure 5 in the transverse moving process of the robot; after the robot transversely moves by the distance of the width of one station, two steering engines are controlled to drive the first bearing wheel and the second bearing wheel to rotate by 90 degrees, finally four horizontal propellers 22 are controlled to push the robot to linearly walk in opposite directions, the directions of the three bearing wheels are shown in figure 3, and the reciprocating operation is carried out so as to realize the bow-shaped operation without turning around.

When the robot walks straightly on the operation wall surface, closed-loop control is carried out according to data collected by the pressure sensor 51, the Doppler velocimeter 52 and the attitude sensor, and the rotating speed and the steering of the four horizontal thrusters 22 are respectively controlled, so that the robot walks straightly forwards at a certain speed.

The controlled variables in the stage are the pitch angle, the depth and the walking speed of the robot. The design steps of the controller comprise: firstly, setting an expected pitch angle to be zero, and issuing an expected depth and an expected walking speed by an upper computer; secondly, constructing errors of a pitch angle, a depth and a walking speed on the basis of acquiring the pitch angle, the depth and the walking speed of the robot by using an attitude sensor, a pressure sensor 51 and a Doppler velocimeter 52; thirdly, according to the spatial layout of the horizontal thruster 22, mapping relations between the thrust of the horizontal thruster and the transverse resultant force, and between the pitching moment and the forward resultant force are established; and finally, constructing a mapping relation, namely a control law, between the thrust of the horizontal thruster and the errors of the pitch angle, the depth and the walking speed by using a PID control strategy.

The step of controlling two steering engines to drive the bearing wheel to rotate for 90 degrees comprises the following steps: firstly, controlling a horizontal thruster 22 to adjust the posture of the robot so that the pitch angle error of the robot reaches a desired value; secondly, issuing an expected steering engine turning angle by an upper computer; thirdly, acquiring the rotation angles of the two steering engines by using position sensors arranged in the first steering engine 34 and the second steering engine 35, and constructing steering engine rotation angle errors; and finally, performing corner closed loop correction based on the steering engine position control mode to enable the steering engine corner error to reach an expected value.

When the robot moves transversely, closed-loop control is performed according to data collected by the pressure sensor 51, the Doppler velocity meter 52, the underwater acoustic positioner 53 and the attitude sensor, the rotating speed and the steering of the four horizontal thrusters 22 are respectively controlled, and the robot is controlled to move transversely by one station width.

The controlled variables at this stage are the traversing distance and the pitching angle of the robot. The design steps of the controller comprise: firstly, setting an expected traversing distance and an expected pitch angle as a station width and zero of the robot respectively; secondly, constructing a sideslip distance and a pitch angle error on the basis of acquiring a sideslip amount, a depth difference, a pitch angle and a roll angle of the robot by using a Doppler velocity meter 52, a pressure sensor 51, a hydroacoustic locator 53 and an attitude sensor; thirdly, according to the spatial layout of the horizontal thruster 22, constructing a mapping relation among the thrust of the horizontal thruster, the transverse resultant force and the pitching moment; and finally, constructing a mapping relation between the thrust of the horizontal thruster and the errors of the traversing distance and the pitch angle by utilizing a PID control strategy, namely a control law.

Example 2: working principle and operation process of head-dropping-free underwater cleaning robot

Referring to fig. 6, the cleaning operation of the present embodiment includes:

s1: starting the robot, controlling the horizontal thruster 22 to push the robot to tour to the wall surface to be cleaned on the water surface, controlling the left and right vertical thrusters 21 to generate thrust in opposite directions to form a turning moment, laterally turning the robot by 90 degrees, controlling the vertical thrusters 21 to generate thrust towards the wall surface, pushing the robot to be attached to the wall surface in a side-standing posture, and ensuring that the three bearing wheels are attached to the wall surface;

s2: adjusting the posture of the robot according to the feedback value of the posture sensor until the robot reaches a horizontal state, starting the cavitation cleaning device 8, and simultaneously controlling the horizontal thruster 22 to push the three bearing wheels to linearly walk forwards to perform cleaning operation;

s3: in the walking process of the robot, comprehensively judging the position of the robot according to the Doppler velocimeter 52 and the underwater sound locator 53, and stopping advancing until the robot is judged to reach the edge of the wall surface (end);

s4: judging whether the cleaning is finished or not according to the information of the pressure sensor 51, the ship body, the planned cleaning area and the like, and if so, finishing the operation and recovering the robot; if the cleaning is not finished, continuing to perform the following steps;

s5: sending a steering engine command, controlling the two steering engines to synchronously rotate for 90 degrees, and respectively driving the first bearing wheel and the second bearing wheel to rotate for 90 degrees;

s6: controlling the horizontal thruster 22 to push the robot to move transversely by one station width and then stopping;

s7: step S5 is executed again, and the robot posture is corrected to the basic level;

s8: controlling the horizontal thruster 22 to push the robot to walk in a straight line in the opposite direction for cleaning;

s9: and (5) repeatedly executing S3-S8, and cleaning according to the shape of a Chinese character 'bow' in a reciprocating manner until the wall surface cleaning operation is finished.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention in any way, and any person skilled in the art can make modifications and equivalents of the above-described embodiments without departing from the scope of the present invention.

Claims (10)

1. The underwater cleaning robot without the head dropping is characterized by comprising a main frame (1), a propelling and adsorbing assembly (2), a walking and steering assembly (3), a sealed electronic cabin (4), a sensing control assembly (5), a light-passing device (6), a buoyancy module (7) and a cavitation cleaning device (8); wherein:

the propelling and adsorbing assembly (2) comprises a plurality of vertical propellers (21) and a plurality of horizontal propellers (22), and the vertical propellers (21) provide rolling moment and adherence adsorption force for the robot; the horizontal thruster (22) provides driving force for the robot to walk along and adhere to the wall;

the walking and steering assembly (3) comprises a first bearing wheel (31), a second bearing wheel (32), a third bearing wheel (33), a first steering engine (34) and a second steering engine (35); the first bearing wheel (31) is driven by the first steering engine (34) to turn and fix the direction, and the second bearing wheel (32) is driven by the second steering engine (35) to turn and fix the direction; the third bearing wheel (33) is a universal wheel;

the sealed electronic cabin (4) comprises robot power supply equipment, control equipment and information transmission equipment;

the sensing control component (5) comprises a pressure sensor (51), a Doppler velocity meter (52), a hydroacoustic locator (53) and a posture sensor, wherein the pressure sensor (51) provides depth information of the robot, the Doppler velocity meter (52) provides moving speed of the robot, the hydroacoustic locator (53) provides position information of the robot, and the posture sensor provides current posture information of the robot;

the light-passing equipment (6) comprises a camera (61) and an illuminating lamp (62), which are simultaneously arranged in the middle of the front end and the rear end of the main frame (1) and are used for illuminating, shooting, recording and observing the environment in front of and behind the robot;

the buoyancy module (7) consists of a plurality of sealed thin-wall shells and is arranged at the front part, the middle part and the rear part of the main frame (1) in a bilateral symmetry manner;

the cavitation cleaning device (8) is composed of three cavitation jet cleaning discs and is arranged in the middle of the main frame (1).

2. The drop-free underwater cleaning robot according to claim 1, wherein the main frame (1) is a double-layer sealed frame structure formed by connecting pipes, and can provide buoyancy far larger than self weight.

3. The drop-free underwater cleaning robot according to claim 1, wherein the first bearing wheel (31), the second bearing wheel (32) and the third bearing wheel (33) are driven wheels, are mounted on the lower side of the main frame (1) in an isosceles triangle shape, and are pushed to move by the horizontal thruster (22).

4. The drop-free underwater cleaning robot according to claim 1, wherein the first steering engine (34) and the second steering engine (35) can rotate 360 degrees and can be self-locked when reaching a target angle; and position sensors are arranged in the first steering engine (34) and the second steering engine (35) and used for feeding back rotation angle information so as to realize steering closed-loop controllability.

5. The method of controlling a headless underwater cleaning robot according to any one of claims 1 to 4, characterized by comprising the steps of:

(1) A plurality of horizontal thrusters (22) are controlled to push the robot to walk on the operation wall surface in a straight line;

(2) When the robot reaches the edge of the operation wall surface, the first steering engine (34) and the second steering engine (35) are controlled to synchronously rotate for 90 degrees, and the first bearing wheel (31) and the second bearing wheel (32) are driven to rotate for 90 degrees;

(3) Then controlling a plurality of horizontal thrusters (22) to push the robot to transversely move for a station width, and then controlling a first steering engine (34) and a second steering engine (35) to drive a first bearing wheel (31) and a second bearing wheel (32) to rotate for 90 degrees;

(4) And finally, a plurality of horizontal propellers (22) are controlled to push the robot to walk linearly in opposite directions, so that the bow-shaped operation without turning around is realized.

6. The method of claim 5, wherein when the robot travels straight on the working wall, the method performs closed-loop control based on the data collected by the pressure sensor (51), the Doppler velocimeter (52), and the attitude sensor, and controls the rotation speed and the steering of the plurality of horizontal thrusters (22), respectively, so that the robot travels straight ahead at a certain speed.

7. The method of claim 6, wherein the controlled variables are a pitch angle, a depth and a traveling speed of the robot when the robot travels straight on the work wall surface, the method comprising:

(1) Firstly, setting an expected pitch angle to be zero, and issuing an expected depth and an expected walking speed by an upper computer;

(2) Secondly, constructing errors of the pitch angle, the depth and the walking speed on the basis of acquiring the pitch angle, the depth and the walking speed of the robot by using an attitude sensor, a pressure sensor (51) and a Doppler velocity meter (52);

(3) Thirdly, according to the spatial layout of the horizontal thruster (22), constructing a mapping relation between the thrust and the transverse resultant force, and between the pitching moment and the forward resultant force of the horizontal thruster (22);

(4) And finally, constructing a mapping relation between the thrust of the horizontal thruster (22) and the errors of the pitch angle, the depth and the walking speed by utilizing a PID control strategy.

8. The control method of the no-drop underwater cleaning robot according to claim 5, wherein the first steering engine (34) and the second steering engine (35) are controlled to drive the first bearing wheel (31) and the second bearing wheel (32) to rotate 90 degrees, and the control method comprises the following steps:

(1) Firstly, controlling a horizontal thruster (22) to adjust the attitude of the robot so that the pitch angle error of the robot reaches an expected value;

(2) Secondly, issuing an expected steering engine turning angle by an upper computer;

(3) Thirdly, acquiring the rotation angles of the two steering engines by using position sensors arranged in the first steering engine (34) and the second steering engine (35) to construct steering engine rotation angle errors;

(4) And finally, performing corner closed loop correction based on the steering engine position control mode to enable the steering engine corner error to reach an expected value.

9. The method of claim 5, wherein when the robot moves laterally, the rotation speed and direction of the plurality of horizontal thrusters (22) are controlled individually to control the robot to traverse a width of one station by performing closed-loop control based on data collected by the pressure sensor (51), the Doppler velocity meter (52), the underwater positioner (53), and the attitude sensor.

10. The method of controlling a headless underwater cleaning robot as claimed in claim 9, wherein the controlled variables are a traverse distance and a pitch angle of the robot when the robot moves laterally, the method including:

(1) Firstly, setting an expected traversing distance and an expected pitch angle as a station width and zero of the robot respectively;

(2) Secondly, constructing a sideslip distance and a pitch angle error on the basis of acquiring a sideslip amount, a depth difference, a pitch angle and a roll angle of the robot by using a Doppler velocity meter (52), a pressure sensor (51), a hydroacoustic positioner (53) and an attitude sensor;

(3) Thirdly, according to the spatial layout of the horizontal thruster (22), constructing a mapping relation between the thrust of the horizontal thruster (22), the transverse resultant force and the pitching moment;

(4) And finally, constructing a mapping relation between the thrust of the horizontal thruster (22) and the sideslip distance and pitch angle errors by utilizing a PID control strategy.

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