Multi-mode underwater detection robot

Abstract

The invention provides a multi-mode underwater detection robot. The robot comprises a body section assembly formed by connecting a plurality of cabin pipe assemblies and power cabin assemblies in series. Joints between the cabin pipe assemblies are connected through joint connecting pieces (7); a steering engine joint piece (3) is arranged at the joint connecting piece, a propeller propelling device (4) is arranged at the power cabin assembly, and when the underwater posture and the propelling working condition of the robot are adjusted, a steering engine of the steering engine joint piece applies force to the joint connecting piece to change the included angle of the joint connecting piece, so that the body section assembly is twisted, and the posture of the robot is converted into different modes; the propelling direction of the propeller propelling device is changed; the problems that an existing underwater robot is single in mode, incapable of adapting to complex environments, low in energy efficiency, difficult in structure maintenance and poor in function expansion capacity can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robots, and in particular to a multi-modal underwater detection robot. BACKGROUND

[0002] With the increasing demand for underwater exploration, the existing underwater robot technology has limitations in single motion mode, low energy efficiency, difficult structure maintenance, single function and poor expandability. Traditional underwater robots are mainly in single motion mode, which is difficult to adapt to complex underwater terrain, has insufficient endurance, is difficult to maintain, and most underwater robots are limited in the number of external devices, with poor function expansion.

[0003] Single motion mode: traditional underwater robots mostly use fixed propeller layout and frame structure, and can only realize straight line motion or simple turning, and cannot adapt to complex underwater terrain (such as coral reef groups and ship interiors).

[0004] Low energy efficiency: single battery system has voltage fluctuation problem, and 12V power supply equipment has insufficient endurance of less than 2 hours when running at full load.

[0005] Difficult structure maintenance: integrated sealed cabin design requires overall disassembly for fault maintenance, and the average maintenance time is more than 4 hours.

[0006] Single function and poor expandability: traditional frame type underwater robots mostly have single function and poor expandability, which leads to slow progress of subsequent iteration and upgrade.

[0007] The present application proposes a multi-modal underwater detection robot to solve the problems of single mode, inability to adapt to complex environment, low energy efficiency, difficult structure maintenance, and poor function expansion. SUMMARY

[0008] The present application proposes a multi-modal underwater detection robot to solve the problems of single mode, inability to adapt to complex environment, low energy efficiency, difficult structure maintenance, and poor function expansion.

[0009] The present application adopts the following technical solutions.

[0010] A multimodal underwater inspection robot comprises a body assembly formed by connecting a plurality of cabin pipe assemblies and a power cabin assembly in series; the joints between the cabin pipe assemblies are connected by joint connectors (7); a steering gear joint (3) is provided at the joint connector, and a propeller propulsion device (4) is provided at the power cabin assembly; when adjusting the underwater posture and propulsion working condition of the robot, a steering gear of the steering gear joint applies force to the joint connector to change the angle of the joint connector, thereby twisting the body assembly so that the robot posture is transformed into a different mode and the propulsion direction of the propeller propulsion device is changed.

[0011] The front end of the body assembly is provided with a snake head (1); the snake head is provided with a lighting lamp (10) and a camera (11), and can also be integrated with a sensing system component;

[0012] The sensing system components include depth sensors, cameras, underwater lights, water quality dissolved oxygen sensors, water quality conductivity sensors and expandable sensors (such as COD, ORP, pH sensors, etc.);

[0013] The robot uses the pressure sensing capability of the depth sensor to measure the pressure value and calculate the depth based on the water density to obtain accurate water depth information and transmit it to the host system;

[0014] The robot collects underwater images through the camera and uses underwater lighting to provide a good lighting environment underwater, which is used to achieve image collection in low visibility underwater.

[0015] The dissolved oxygen sensor and the water conductivity sensor are used to detect the dissolved oxygen and conductivity values ​​in the water. Through the analysis of the values, a comprehensive assessment of the water quality can be made, which can be used to enable the robot to detect the water quality in the water.

[0016] An interface for expandable sensors is reserved on the robot for subsequent functional iteration and upgrade, which is used to realize the strong functional expandability of the multimodal underwater detection robot.

[0017] Motion control system: This includes thrusters, servos, and expandable peripherals (such as robotic arms and motors). The thrusters provide the multimodal underwater inspection robot's primary power source in the water, enabling it to move forward, backward, ascend, and descend. The servos control the two-degree-of-freedom rotation of the robot's four joints, enabling the robot's mode transitions. Expandable peripherals are reserved for subsequent functional upgrades, ensuring the robot's highly scalable functionality.

[0018] The steering gear joint comprises a waterproof shell for wrapping a steering gear structure, and the steering gear structure is provided with two steering gears (23) symmetrically distributed at 90 degrees.

[0019] The cabin tube assembly is used to form a robot main body frame, including a front cabin tube (2), a middle cabin tube (5), and a rear cabin tube (6);

[0020] The power cabin assembly is used to form a propulsion system installation base of the robot, and includes a front power cabin (8) located between the front cabin tube and the middle cabin tube, and a rear power cabin (9) located between the middle cabin tube and the rear cabin tube.

[0021] There are four joint connectors in total. The steering gear joint is fixed to a cabin pipe assembly or a power cabin assembly at one end of the joint connector and is connected to the cabin pipe assembly or the power cabin assembly at the other end of the joint connector via a coupling (42). Each steering gear joint is provided with two steering gears arranged vertically to a horizontal plane. A total of eight steering gears are provided at all steering gear joints of the robot. When the robot's posture mode needs to be changed, the steering gear at the steering gear joint drives the joint connector to rotate a required angle through the coupling. By changing the rotation angle of each joint connector, the robot is transformed into a different posture mode.

[0022] The propeller propulsion device includes 8 groups of symmetrically distributed propulsion units, which are composed of 4 vertically symmetrically distributed propeller propellers and 4 inclined propeller propellers, of which the 4 inclined propellers have an inclination angle of 45 degrees.

[0023] When the robot performs an ascent or descent action, the working condition of the propulsion unit is selected according to the position of the eight symmetrically distributed propulsion units in the current posture of the robot. If the four vertically symmetrical propeller thrusters are in a horizontal state, the four horizontal propeller thrusters are responsible for outputting the thrust for ascent and descent. If the four inclined propeller thrusters are in a horizontal state, the four inclined propeller thrusters are responsible for outputting the thrust for ascent and descent.

[0024] The robot's control system includes the host computer control system, motion control system, perception system, and power supply system;

[0025] Host computer control system: This includes the multi-modal underwater inspection robot's motion control system, perception system, and power supply system. It is used to control the robot's various functions, observe its surroundings in real time, and monitor battery voltage status in real time.

[0026] Motion control system: includes propeller thrusters, servos, and expandable peripherals (such as robotic arms, motors, and other peripherals). The propeller thrusters provide the multimodal underwater inspection robot with power in the water, used to achieve the multimodal underwater inspection robot's forward, backward, ascent, and descent; the servos control the two-degree-of-freedom rotation of the joint connectors, used to achieve the multimodal underwater inspection robot's mode conversion, and reserve expandable peripherals for subsequent functional iteration and upgrade, used to achieve the multimodal underwater inspection robot's strong functional scalability.

[0027] Power supply system: including power management board 1 (21), power management board 2 (32), 24V lithium battery pack 1 (19), 24V lithium battery pack 2 (36). The power management board has built-in 5V, 12V, and 24V power outputs. The power management board monitors the battery voltage, assists the main controller in controlling the multi-modal underwater detection robot, detects and issues warnings on the battery power, and ensures that the multi-modal underwater detection robot has sufficient power to move. It also provides 5V power to the main controller and steering gear light of the multi-modal underwater detection robot, and provides 24V power to the propeller and underwater lighting of the multi-modal underwater detection robot.

[0028] When the control system is working, the robot's main controller uses the single-board computer as the control center and communicates with the slave controller through the IIC communication protocol. The host computer sends signals to the main controller.

[0029] The main controller sends signals to the slave controller through IIC communication. The slave controller receives the signal and sends a PWM signal to the electronic regulator to control the propeller propulsion device, realizing the motion control function of the multi-modal underwater detection robot. The sent PWM signal also controls the servo to realize the rotation of the joints of the multi-modal underwater detection robot.

[0030] The robot's control system uses signals from the power management board to monitor the battery charge status in real time at the host computer. It is connected to the remote host computer via a cable to collect and transmit signals in real time and communicate with the single-board computer.

[0031] The motion control of the robot comprises the following steps:

[0032] Step A1: Turn on the robot power and complete the initialization of various sensors and actuators, including thrusters, servos, sensors, and power supply systems. The system verifies that all modules are operating normally by detecting power status and device connections.

[0033] Step A2: Connect the robot to the remote PC control system through a dedicated cable to ensure smooth communication between the host computer and the robot.

[0034] Step A3: Open the PC and start the dedicated robot control software or interface on the PC to prepare for control operations. At this point, the host computer establishes a preliminary connection with the robot's control system.

[0035] Step A4: Open the host computer system and start the host control system in the PC software interface. This system is responsible for sending motion commands to the robot and receiving feedback signals from the robot. At this point, the robot is fully connected to the host computer system and is ready to receive control commands.

[0036] Step A5: Connect the remote control and buttons, establishing a connection between the remote control and the button host computer system. Ensure that the remote control and buttons can send operating instructions to the host computer, which then transmits them to the robot. After this step is completed, the operator can control the robot in real time using the remote control and buttons.

[0037] Step A6: Controlling the thrusters and servos: The host computer system transmits motion commands from the remote controller to the thrusters and servos. These commands generate thrust and rotation angles, controlling the robot's basic movements of forward, backward, ascent, and descent, as well as rotation at any joint angle.

[0038] Step A7: Control the servos at the joints. The servo control module controls the rotation of the eight servos according to the host computer's instructions, enabling the robot to switch between multiple modes of posture, ensuring that the robot can use different modes to cope with different working environments.

[0039] The robot postures include S-type, I-type, O-type, L-type, and U-type;

[0040] When the robot's posture mode is switched, the corresponding servos are transformed accordingly. When the robot's posture needs to be switched to S-shaped mode, the servos in the vertical position of the robot's four joints are rotated to a certain corresponding angle, making the robot present an S-shaped posture; the same is true for switching to other modes.

[0041] In all robot posture modes, if the robot does not need to ascend or dive, only the four tilted propellers are in operation. No matter how the robot rolls during operation, the four tilted propellers always maintain their tilted position. The propellers are fixed to the robot shell, and changing modes does not change the physical position of the propellers.

[0042] The entire robot connection structure is rigidly connected, and the joints and each cabin tube are fixedly connected (the overall connection structure can be clearly seen in the three-view drawing, which is fixed);

[0043] The method for determining the attitude of each propeller thruster specifically includes:

[0044] (1) Based on the rudder rotation angle of the attitude determination: In the multimodal underwater detection robot, the attitude of each propeller is directly controlled by the rotation angle of the corresponding rudder; The system determines the current attitude of the propeller by the following steps:

[0045] Step A: The main controller reads the rotation angle of each rudder in real time (feedback signal through encoder or potentiometer), and compares it with the preset "horizontal attitude" and "inclined attitude" angle range;

[0046] Horizontal attitude determination: When the rudder rotation angle is 0°±5° (calibration error range), it is determined that the corresponding propeller is in a horizontal state;

[0047] Inclined attitude determination: When the rudder rotation angle is 45°±5° (calibration error range), it is determined that the corresponding propeller is in an inclined state;

[0048] Step B: The main controller dynamically updates the propeller attitude database according to the rudder angle information, and marks the current state of each propeller (horizontal / inclined);

[0049] (2) Inertial measurement unit IMU-based attitude auxiliary calibration, specifically:

[0050] The robot monitors the overall attitude data of the robot (such as pitch angle, roll angle) in real time with the IMU (integrated gyroscope, accelerometer) carried in the controller;

[0051] When there is a conflict between the rudder angle and the robot attitude data feedback by the IMU (for example: the rudder shows horizontal but the IMU detects that the robot is inclined), the robot system triggers the self-checking program, and the actual attitude of the propeller is calibrated preferentially with the IMU data;

[0052] The method for determining the direction of the robot propeller in the motion coordinate system is as follows:

[0053] (1) Propeller thrust direction modeling:

[0054] The thrust direction of each propeller is determined by its installation position and the rudder rotation angle:

[0055] Horizontal propeller: The thrust direction is parallel to the robot main axis (X-axis direction), which is used for ascending / descending.

[0056] Inclined propeller: The thrust direction is at an angle of 45° with the robot main axis (Y-axis and Z-axis components coexist), which is used for horizontal propulsion or auxiliary attitude adjustment;

[0057] (2) Thrust synthesis in the motion coordinate system

[0058] The main controller executes the following operations according to the target motion instruction (such as ascending, descending, turning) combined with the current propeller attitude data:

[0059] Step A: Retrieve the thruster status (level / tilt) from the attitude database.

[0060] Step B: Select the currently available propeller thruster group (e.g., horizontal group or tilt group) as the power source;

[0061] Step C: Based on the thrust vectoring model, calculate the direction and magnitude of the resultant force of the selected thruster group to ensure that the direction of the resultant force is consistent with the target motion direction;

[0062] Step D: Dynamically adjust the speed of each propeller through PWM signals to achieve precise motion control.

[0063] Example: Floating Control Flow

[0064] If the current mode is "horizontal thruster dominant", four horizontal thrusters are selected to output a vertical upward force (in the Z-axis direction);

[0065] If the current mode is "Tilt Thruster Dominant", the tilt thrusters adjust the servo angles to superimpose the thrust components in the Z-axis direction, generating an upward buoyancy force.

[0066] When the robot is working, the suppression and compensation scheme of the reaction force of each joint is as follows:

[0067] (1) Rigid structure design

[0068] Joint rigid connection: The joints (23, 43) where the steering gear is located are fixed to the cabin pipes (2, 5, 6) and the power cabin shell (8, 9) with high-strength materials and rigid couplings (42), ensuring that the overall deformation of the joints is less than 0.5 mm when the steering gear rotates, thereby minimizing the attitude deviation caused by the reaction force.

[0069] The joints where the servos are located will also be affected by reaction forces, which may cause changes in the posture of the joints where the servos are located. What the robot needs is a change in mode morphology. Slight changes in posture will not affect the final mode change.

[0070] When the robot is working, the thruster working state is controlled by the following time-sharing control strategy method:

[0071] Attitude adjustment stage: When the servo executes mode switching (such as S-type to I-type), propeller thrusters 1 to 8 stop working (PWM signal duty cycle drops to 0%) to prevent propeller thrust from interfering with the joint attitude adjustment process.

[0072] Movement execution phase: After the servo angle is locked, the propeller thrusters are restarted according to the target command (such as ascending or descending) to ensure that the thrust direction matches the current attitude.

[0073] The present invention has the following advantages:

[0074] 1. Efficient mode conversion: It can achieve multiple motion modes, including S-type, I-type, O-type, L-type, and U-type, adapting to complex underwater environments (such as narrow pipes and rugged terrain). The servos 1-8 control four sets of two-degree-of-freedom joints. The master and slave controllers collaborate via the IIC protocol to generate multi-joint linkage commands. The symmetrical distribution of the thrusters 1-8 provides multi-dimensional power.

[0075] 2. The 24V dual lithium battery pack is used in conjunction with the power management board to improve the battery life and support 5V / 12V / 24V multi-level voltage intelligent distribution.

[0076] 3. The present invention uses a multi-layer sealing structure with sealing flanges, a distributed sealing solution with airtight screws, and cable waterproofing with threading screws, thereby improving structural reliability.

[0077] 4. The structure of the present invention is easy to maintain and has a distributed structure with multiple modules. Unlike traditional integrated robots that require disassembly of the entire machine, the distributed structure can be disassembled and replaced separately according to the damaged parts, reducing maintenance time and maintenance costs.

[0078] 5. The present invention has strong functional scalability and reserves a large number of scalable interfaces in the motion control system-level perception system, laying the foundation for subsequent functional iteration and upgrade. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0080] Attachment Figure 1 It is a main view schematic diagram of the present invention;

[0081] Attachment Figure 2 It is a three-dimensional schematic diagram of the present invention;

[0082] Attachment Figure 3 It is a schematic diagram of the snake head of the present invention (left schematic view);

[0083] Attachment Figure 4 It is a right-side view schematic diagram of the present invention;

[0084] Attachment Figure 5 This is a schematic cross-sectional view of the internal structure of the detection cabin (front cabin tube) of the cabin tube assembly of the multi-modal underwater detection machine;

[0085] Attachment Figure 6 1 is a schematic cross-sectional view of the internal structure of the front power compartment of the multimodal underwater inspection robot of the present invention;

[0086] Attachment Figure 7 This is a schematic cross-sectional diagram of the internal structure of the main control cabin (middle cabin tube) of the cabin tube assembly of the multi-modal underwater inspection robot;

[0087] Attachment Figure 8 This is a schematic cross-sectional diagram of the internal structure of the rear power cabin of the multimodal underwater inspection robot;

[0088] Attachment Figure 9 This is a schematic cross-sectional view of the internal structure of the energy cabin (rear cabin tube) of the cabin tube assembly of the multimodal underwater inspection robot;

[0089] Attachment Figure 10 This is a schematic diagram of the joint structure of the multimodal underwater detection robot;

[0090] Attachment Figure 11 This is another schematic diagram of the joint structure of the multimodal underwater inspection robot;

[0091] Attachment Figure 12 It is a schematic diagram of the internal structure cross-section of the multimodal underwater inspection robot. DETAILED DESCRIPTION

[0092] As shown in the figure, a multimodal underwater inspection robot includes a body assembly composed of multiple cabin pipe assemblies and power cabin assemblies connected in series; the joints between the cabin pipe assemblies are connected by joint connectors 7; the joint connectors are provided with servo joints 3, and the power cabin assemblies are provided with propeller propulsion devices 4. When adjusting the underwater posture and propulsion working conditions of the robot, the servo of the servo joint applies force to the joint connector to change the angle of the joint connector, so that the body assembly is twisted to transform the robot posture into different modes and change the propulsion direction of the propeller propulsion device.

[0093] The front end of the body assembly is provided with a snake head 1; the snake head is provided with a lighting lamp 10 and a camera 11, and can also be integrated with a sensing system component;

[0094] The sensing system components include depth sensors, cameras, underwater lights, water quality dissolved oxygen sensors, water quality conductivity sensors and expandable sensors such as COD, ORP, pH sensors, etc.

[0095] The robot uses the pressure sensing capability of the depth sensor to measure the pressure value and calculate the depth based on the water density to obtain accurate water depth information and transmit it to the host system;

[0096] The robot collects underwater images through the camera and uses underwater lighting to provide a good lighting environment underwater, which is used to achieve image collection in low visibility underwater.

[0097] The dissolved oxygen sensor and the water conductivity sensor are used to detect the dissolved oxygen and conductivity values ​​in the water. Through the analysis of the values, a comprehensive assessment of the water quality can be made, which can be used to enable the robot to detect the water quality in the water.

[0098] The interface of the extensible sensor is reserved at the robot, for subsequent functional iteration upgrade, to realize the strong expandability of the multi-modal underwater detection robot.

[0099] The motion control system includes propeller, rudder and extensible peripherals such as mechanical arm, motor and the like. The propeller provides the main source of power for the multi-modal underwater detection robot in water, for realizing the advancing, retreating, floating up, diving and the like of the multi-modal underwater detection robot. The rudder controls the two-degree-of-freedom rotation of the four joints, for realizing the mode conversion of the multi-modal underwater detection robot. The extensible peripherals are reserved for subsequent functional iteration upgrade, to realize the strong expandability of the multi-modal underwater detection robot.

[0100] The rudder joint member includes a waterproof shell for wrapping the rudder structure, and the rudder structure is provided with two rudders 23 symmetrically distributed at 90 degrees.

[0101] The cabin pipe assembly is used to constitute the robot main body frame, including front cabin pipe 2, middle cabin pipe 5 and rear cabin pipe 6.

[0102] The power cabin assembly is used to constitute the installation base of the propulsion system of the robot, including front power cabin 8 between the front cabin pipe and the middle cabin pipe, and rear power cabin 9 between the middle cabin pipe and the rear cabin pipe.

[0103] The joint connecting member is four in total. The rudder joint member is fixed at the cabin pipe assembly or the power cabin assembly at one end of the joint connecting member, and is connected to the cabin pipe assembly or the power cabin assembly at the other end of the joint connecting member through the shaft coupling 42. Each rudder joint member is provided with two rudders vertically arranged with the horizontal plane. Eight rudders are provided at all the rudder joint members of the robot. When the posture mode of the robot needs to be changed, the rudders at the rudder joint members drive the joint connecting member to rotate by the required angle through the shaft coupling, and the robot is changed into different posture modes by changing the rotation angle of each joint connecting member.

[0104] The propeller propulsion device includes 8 groups of symmetrically distributed propulsion units, which are composed of 4 vertically symmetrically distributed propellers and 4 obliquely distributed propellers. The oblique angle of the 4 oblique propellers is 45 degrees.

[0105] When the robot performs the floating up action or the diving action, the working condition of the propulsion unit is selected according to the position of the 8 groups of symmetrically distributed propulsion units under the current posture of the robot. If the four vertically symmetric propellers are in the horizontal state, the four horizontal propellers are responsible for outputting the floating up and diving thrust. If the four oblique propellers are in the horizontal state, the four oblique propellers are responsible for outputting the floating up and diving thrust.

[0106] The robot's control system includes the host computer control system, motion control system, perception system, and power supply system;

[0107] Host computer control system: This includes the multi-modal underwater inspection robot's motion control system, perception system, and power supply system. It is used to control the robot's various functions, observe its surroundings in real time, and monitor battery voltage status in real time.

[0108] Motion control system: includes propeller thrusters, servos, and expandable peripherals such as robotic arms and motors. The propeller thrusters provide the multimodal underwater inspection robot with power in the water, enabling it to move forward, backward, ascend, and descend. The servos control the two-degree-of-freedom rotation of the joint connectors, enabling the multimodal underwater inspection robot to switch modes. Expandable peripherals are reserved for subsequent functional iterations and upgrades, enabling the multimodal underwater inspection robot to have strong functional scalability.

[0109] Power supply system: includes power management board 1 21, power management board 2 32, 24V lithium battery pack 19, and 24V lithium battery pack 2 36. The power management board has built-in 5V, 12V, and 24V power outputs. It monitors battery voltage, assists the main controller in controlling the multimodal underwater inspection robot, detects battery charge and provides early warnings to ensure the multimodal underwater inspection robot has sufficient power for movement. It also provides 5V power to the multimodal underwater inspection robot's main controller and steering gear lights, and 24V power to the multimodal underwater inspection robot's thrusters and underwater lights.

[0110] When the control system is working, the robot's main controller uses the single-board computer as the control center and communicates with the slave controller through the IIC communication protocol. The host computer sends signals to the main controller.

[0111] The main controller sends signals to the slave controller through IIC communication. The slave controller receives the signal and sends a PWM signal to the electronic regulator to control the propeller propulsion device, realizing the motion control function of the multi-modal underwater detection robot. The sent PWM signal also controls the servo to realize the rotation of the joints of the multi-modal underwater detection robot.

[0112] The robot's control system uses signals from the power management board to monitor the battery charge status in real time at the host computer. It is connected to the remote host computer via a cable to collect and transmit signals in real time and communicate with the single-board computer.

[0113] The motion control of the robot comprises the following steps:

[0114] Step A1: Turn on the robot power and complete the initialization of various sensors and actuators, including thrusters, servos, sensors, and power supply systems. The system verifies that all modules are operating normally by detecting power status and device connections.

[0115] Step A2: Connect the robot to the remote PC control system through a dedicated cable to ensure smooth communication between the host computer and the robot.

[0116] Step A3: Open the PC and start the dedicated robot control software or interface on the PC to prepare for control operations. At this point, the host computer establishes a preliminary connection with the robot's control system.

[0117] Step A4: Open the host computer system and start the host control system in the PC software interface. This system is responsible for sending motion commands to the robot and receiving feedback signals from the robot. At this point, the robot is fully connected to the host computer system and is ready to receive control commands.

[0118] Step A5: Connect the remote control and buttons, establishing a connection between the remote control and the button host computer system. Ensure that the remote control and buttons can send operating instructions to the host computer, which then transmits them to the robot. After this step is completed, the operator can control the robot in real time using the remote control and buttons.

[0119] Step A6: Controlling the thrusters and servos: The host computer system transmits motion commands from the remote controller to the thrusters and servos. These commands generate thrust and rotation angles, controlling the robot's basic movements of forward, backward, ascent, and descent, as well as rotation at any joint angle.

[0120] Step A7: Control the servos at the joints. The servo control module controls the rotation of the eight servos according to the host computer's instructions, enabling the robot to switch between multiple modes of posture, ensuring that the robot can use different modes to cope with different working environments.

[0121] The robot postures include S-type, I-type, O-type, L-type, and U-type;

[0122] When the robot's posture mode is switched, the corresponding servos are transformed accordingly. When the robot's posture needs to be switched to S-shaped mode, the servos in the vertical position of the robot's four joints are rotated to a certain corresponding angle, making the robot present an S-shaped posture; the same is true for switching to other modes.

[0123] In all modes of the robot, if the robot does not need to float or dive, only four inclined propellers are running, regardless of how the robot rolls when running, the four inclined propellers always remain in the inclined position, and the propellers are fixedly connected with the robot shell, and the mode conversion does not change the physical position of the propeller;

[0124] The overall robot connection structure is rigid connection, and the joint is fixedly connected with each cabin pipe (in the three views, the overall connection structure can be clearly seen, which is fixed and unchanged) ;

[0125] The posture determination method of each propeller is specifically as follows:

[0126] (1) Posture determination based on the rotation angle of the rudder: in the multi-mode underwater detection robot, the posture of each propeller is directly controlled by the rotation angle of the corresponding rudder; the system determines the current posture of the propeller through the following steps:

[0127] Step A: The main controller reads the rotation angle of each rudder in real time (feedback signal through the encoder or potentiometer), and compares it with the preset angle range of the "horizontal posture" and "inclined posture";

[0128] Horizontal posture determination: when the rotation angle of the rudder is 0°±5° (calibration error range), it is determined that the corresponding propeller is in a horizontal state;

[0129] Inclined posture determination: when the rotation angle of the rudder is 45°±5° (calibration error range), it is determined that the corresponding propeller is in an inclined state;

[0130] Step B: The main controller dynamically updates the propeller posture database according to the rudder angle information, and marks the state (horizontal / inclined) of each propeller at present;

[0131] (2) Inertial measurement unit (IMU) assisted posture calibration, specifically:

[0132] The robot carries an IMU (integrated gyroscope and accelerometer) to monitor the overall posture data (such as pitch angle and roll angle) of the robot in real time;

[0133] When there is a conflict between the rudder angle and the robot posture data feedback by the IMU (for example: the rudder shows horizontal but the IMU detects that the robot is inclined), the robot system triggers the self-checking program, and the actual posture of the propeller is calibrated preferentially by the IMU data;

[0134] The determination method of the robot propulsion direction in the motion coordinate system is specifically as follows:

[0135] (1) Propeller thrust direction modeling:

[0136] The thrust direction of each thruster is determined by its installation position and the servo rotation angle:

[0137] Horizontal thruster: The thrust direction is parallel to the axis of the robot body (X-axis direction) and is used for ascent / descent.

[0138] Tilt thruster: The thrust direction forms a 45° angle with the robot's main axis (Y-axis and Z-axis components coexist), used for horizontal propulsion or auxiliary posture adjustment;

[0139] (2) Thrust synthesis in the motion coordinate system

[0140] The main controller performs the following operations based on the target motion instructions (such as ascending, descending, and turning) and the current thruster attitude data:

[0141] Step A: Retrieve the thruster status (level / tilt) from the attitude database.

[0142] Step B: Select the currently available propeller thruster group (e.g., horizontal group or tilt group) as the power source;

[0143] Step C: Based on the thrust vectoring model, calculate the direction and magnitude of the resultant force of the selected thruster group to ensure that the direction of the resultant force is consistent with the target motion direction;

[0144] Step D: Dynamically adjust the speed of each propeller through PWM signals to achieve precise motion control.

[0145] Example: Floating Control Flow

[0146] If the current mode is "horizontal thruster dominant", four horizontal thrusters are selected to output a vertical upward force (in the Z-axis direction);

[0147] If the current mode is "Tilt Thruster Dominant", the tilt thrusters adjust the servo angles to superimpose the thrust components in the Z-axis direction, generating an upward buoyancy force.

[0148] When the robot is working, the suppression and compensation scheme of the reaction force of each joint is as follows:

[0149] (1) Rigid structure design

[0150] Joint rigid connection: The joints (23, 43) where the steering gear is located are fixed to the cabin pipes (2, 5, 6) and the power cabin shell (8, 9) with high-strength materials and rigid couplings (42), ensuring that the overall deformation of the joints is less than 0.5 mm when the steering gear rotates, thereby minimizing the attitude deviation caused by the reaction force.

[0151] The joints where the servos are located will also be affected by reaction forces, which may cause changes in the posture of the joints where the servos are located. What the robot needs is a change in mode morphology. Slight changes in posture will not affect the final mode change.

[0152] When the robot is working, the thruster working state is controlled by the following time-sharing control strategy method:

[0153] Attitude adjustment stage: When the servo executes mode switching (such as S-type to I-type), propeller thrusters 1 to 8 stop working (PWM signal duty cycle drops to 0%) to prevent propeller thrust from interfering with the joint attitude adjustment process.

[0154] Movement execution phase: After the servo angle is locked, the propeller thrusters are restarted according to the target command (such as ascending or descending) to ensure that the thrust direction matches the current attitude.

[0155] Example:

[0156] like Figures 3 to 10 As shown, this example uses a multi-layer sealing structure using a sealing flange (18), a distributed sealing solution using airtight screws (16, 24, 26, 29, 34), and cable waterproofing using threading screws (15, 25), thereby improving structural reliability.

[0157] like Figures 3 to 10 As shown, the multimodal underwater inspection robot includes 1-snake head shell, 2, 5, 6-cabin tubes (front cabin tube 2, middle cabin tube 5, rear cabin tube 6), 3-servo joint shell, 4-propeller thruster; 7, 39-joint connectors (joint connector A7, joint connector B39); 8-front power compartment shell, 9-rear power compartment shell, 10, 17-lights (underwater lighting A10, underwater lighting B17); 11, 20-cameras (camera A11, camera B20), 12-knob switch, 13-watertight connector, 14-depth sensor, 15, 25-threading screws (threading screw A15, threading screw B25); 16, 24, 26, 29, 34-airtight screws (airtight screws Airtight screw A16, airtight screw B24, airtight screw C26, airtight screw D29, airtight screw E34); 18-sealing flange; 19, 36-lithium battery pack (lithium battery pack A19, lithium battery pack B36), 21, 32-power management board (power management board A21, power management board B32), 22-cabin bracket, 23, 43-servo (servo A23, servo B43), 27-function expansion board, 28-connection board, 30-main controller; 31, 37-counterweight chamber (counterweight chamber A31, counterweight chamber B37), 33-slave controller, 35-power carrier module, 38-hatch cover, 40-joint servo fixing main part, 41-joint servo fixing subpart, 42-coupling.

[0158] Main frame structure:

[0159] Snake head shell 1: robot front-end structure, with internal integrated perception system components;

[0160] Cabin tube assembly 2, 5, 6: including the front cabin tube 2, the middle cabin tube 5, and the rear cabin tube 6, forming the robot main frame;

[0161] Servo joint housing 3: A waterproof housing that wraps the servo structure. Each joint consists of two servos symmetrically distributed at 90 degrees.

[0162] Power compartment assembly: The front power compartment shell 8 and the rear power compartment shell 9 constitute the propulsion system installation base.

[0163] Power and actuator:

[0164] Propeller thrusters 4: 4 sets of symmetrically distributed propulsion units, consisting of 4 vertically symmetrically distributed propeller thrusters and 4 tilted propeller thrusters, of which the 4 tilted propeller thrusters have an inclination angle of 45 degrees;

[0165] Servo components 23 and 43 (servo component A23 and servo component B43): There are 4 sets of two-degree-of-freedom servo joints in total, corresponding to 4 joint mechanisms respectively.

[0166] Perception system:

[0167] Depth sensor 14: integrated on the rear compartment tube hatch;

[0168] Vision module: includes cameras 11, 20 and matching underwater lights 10, 17.

[0169] Control system:

[0170] Main controller 30: A single-board computer is used as the control center and is installed on the internal bracket of the middle cabin tube;

[0171] Slave controller 33: communicates with the master controller via IIC protocol;

[0172] Function expansion board 27: an interface reserved for subsequent function iterations;

[0173] Power carrier module 35: realizes long-distance signal transmission.

[0174] Energy supply and distribution system:

[0175] Lithium battery pack 19,36: 24V dual battery system;

[0176] Power management board 21, 32: integrated 5V / 12V / 24V multi-level voltage conversion.

[0177] Auxiliary structure:

[0178] Counterweight chambers 31, 37: sealed chambers with adjustable buoyancy;

[0179] Airtight connectors: including threading screws 15, 25, airtight screws 16, 24, 26, 29, 34;

[0180] Sealing flange 18: Waterproof connection structure between compartments.

[0181] Watertight connector 13 realizes waterproof connection of host computer signal cable

[0182] Main structure connection:

[0183] The snake head housing 1 is sealed to the front compartment pipe 2 via a sealing flange 18;

[0184] Each cabin pipe 2, 5, 6 and the power cabin shell 8, 9 are axially sealed connected to the joint connector 7, 39 through the sealing flange 18.

[0185] Joint structure connection:

[0186] The two servos 23 and 43 are fixedly connected by the 40-joint servo fixing main part and the 41-joint servo fixing auxiliary part, and are combined into a joint rotation mechanism;

[0187] The steering gears 23 and 43 are fixedly connected to the joint connectors 7 and 39 via the coupling 42 , and the rotation of the steering gears 23 and 43 drives the rotation of the joint connectors 7 and 39 .

[0188] Power system connection:

[0189] Four propellers 4 are horizontally symmetrical and four are axially symmetrically mounted on the power cabin housing 8, 9;

[0190] The steering gears 23 and 43 form a two-degree-of-freedom rotation pair with the adjacent compartments through the joint connectors 7 and 39.

[0191] Electronic control system connection:

[0192] The master controller 30 is connected to the slave controller 33 via the connection board 28;

[0193] The slave controller 33 integrates the IIC bus to connect the drive circuits of each actuator;

[0194] The power management boards 21 and 32 realize cross-compartment power transmission through threading screws 15 and 25.

[0195] Perception system integration:

[0196] The depth sensor 14 is mounted on the rear tube hatch cover 38;

[0197] The cameras 11, 20 adjust the pitch angle through the servo joint housing 3 and the servo assembly 23;

[0198] Underwater lighting lamps 10, 17 are installed on the snake head shell to provide lighting conditions underwater.

Claims

1. A multimodal underwater inspection robot, characterized by: The robot comprises a body assembly formed by connecting a plurality of cabin pipe assemblies and a power cabin assembly in series; the joints between the cabin pipe assemblies are connected by joint connectors (7); a steering gear joint (3) is provided at the joint connector, and a propeller propulsion device (4) is provided at the power cabin assembly. When adjusting the underwater posture and propulsion working condition of the robot, the steering gear of the steering gear joint applies force to the joint connector to change the angle of the joint connector, thereby twisting the body assembly so that the robot posture is transformed into a different mode and the propulsion direction of the propeller propulsion device is changed.

2. The multimodal underwater inspection robot according to claim 1, characterized in that: The front end of the body assembly is provided with a snake head (1); the snake head is provided with a lighting lamp (10), a camera (11), and an integrated sensing system component; The perception system components include depth sensors, cameras, underwater lights, water dissolved oxygen sensors, water conductivity sensors and expandable sensors.

3. The multimodal underwater inspection robot according to claim 1, characterized in that: The steering gear joint comprises a waterproof shell for wrapping a steering gear structure, and the steering gear structure is provided with two steering gears (23) symmetrically distributed at 90 degrees.

4. The multimodal underwater inspection robot according to claim 1, characterized in that: The cabin tube assembly is used to form a robot main body frame, including a front cabin tube (2), a middle cabin tube (5), and a rear cabin tube (6); The power cabin assembly is used to form a propulsion system installation base of the robot, and includes a front power cabin (8) located between the front cabin tube and the middle cabin tube, and a rear power cabin (9) located between the middle cabin tube and the rear cabin tube.

5. The multimodal underwater inspection robot according to claim 4, characterized in that: There are four joint connectors in total. The steering gear joint is fixed to a cabin pipe assembly or a power cabin assembly at one end of the joint connector and is connected to the cabin pipe assembly or the power cabin assembly at the other end of the joint connector via a coupling (42). Each steering gear joint is provided with two steering gears arranged vertically to a horizontal plane. A total of eight steering gears are provided at all steering gear joints of the robot. When the robot's posture mode needs to be changed, the steering gear at the steering gear joint drives the joint connector to rotate a required angle through the coupling. By changing the rotation angle of each joint connector, the robot is transformed into a different posture mode.

6. The multimodal underwater inspection robot according to claim 5, characterized in that: The propeller propulsion device includes 8 groups of symmetrically distributed propulsion units, which are composed of 4 vertically symmetrically distributed propeller propellers and 4 inclined propeller propellers, of which the 4 inclined propellers have an inclination angle of 45 degrees.

7. The multimodal underwater inspection robot according to claim 6, characterized in that: When the robot performs an ascent or descent action, the working condition of the propulsion unit is selected according to the position of the eight symmetrically distributed propulsion units in the current posture of the robot. If the four vertically symmetrical propeller thrusters are in a horizontal state, the four horizontal propeller thrusters are responsible for outputting the thrust for ascent and descent. If the four inclined propeller thrusters are in a horizontal state, the four inclined propeller thrusters are responsible for outputting the thrust for ascent and descent.

8. The multimodal underwater inspection robot according to claim 5, characterized in that: The robot's control system includes the host computer control system, motion control system, perception system, and power supply system; Host computer control system: including the motion control system, perception system, and power supply system of the multi-modal underwater inspection robot; Motion control system: includes propeller thrusters, servos, and expandable peripherals; propeller thrusters provide the multi-modal underwater inspection robot with power in the water, used to achieve the multi-modal underwater inspection robot's forward, backward, ascent, and dive; servos control the two-degree-of-freedom rotation of the joint connector to achieve the multi-modal underwater inspection robot's mode conversion; When the control system is working, the robot's main controller uses the single-board computer as the control center and communicates with the slave controller through the IIC communication protocol. The host computer sends signals to the main controller. The master controller sends a signal to the slave controller through IIC communication. The slave controller receives the signal and sends a PWM signal to the electronic regulator to control the propeller propulsion device, thereby realizing the motion control function of the multi-modal underwater detection robot. The PWM signal sent also controls the servo to realize the rotation of the joints of the multi-modal underwater detection robot. The robot's control system uses signals from the power management board to monitor the battery charge status in real time at the host computer. It is connected to the remote host computer via a cable to collect and transmit signals in real time and communicate with the single-board computer.

9. The multimodal underwater inspection robot according to claim 5, characterized in that: The motion control of the robot comprises the following steps: Step A1: Turn on the robot power and complete the initialization of various sensors and actuators, including thrusters, servos, sensors, and power supply systems. The system verifies that all modules are operating normally by detecting power status and device connections. Step A2: Connect the robot to the remote PC control system through a dedicated cable to ensure smooth communication between the host computer and the robot. Step A3: Open the PC and start the dedicated robot control software or interface on the PC to prepare for control operations; Step A4: Open the host computer system and start the host computer control system in the PC software interface. This system is responsible for sending motion commands to the robot and receiving feedback signals from the robot; Step A5: Connect the remote control and buttons, establish a connection between the remote control and the button host computer system, and ensure that the remote control and buttons can send operation instructions to the host computer and pass them to the robot through the host computer. Step A6: Control the thrusters and servos. The host computer system transmits the motion commands from the remote control to the thrusters and servos. The thrusters and servos generate corresponding thrust and rotation angles according to the commands, controlling the robot to achieve basic movements such as forward, backward, ascent, and descent in the water, as well as rotation at any joint angle. Step A7: Control the servos at the joints. The servo control module controls the rotation of the eight servos according to the host computer's instructions, realizing the switching of the robot's posture in multiple modes. The robot postures include S-type, I-type, O-type, L-type, and U-type; When the robot's posture mode is switched, the corresponding servos are transformed accordingly. When the robot's posture needs to be switched to S-shaped mode, the servos in the vertical position of the robot's four joints are rotated to a certain corresponding angle, making the robot present an S-shaped posture. The same applies to transitioning to other modes.

10. The multimodal underwater inspection robot according to claim 9, characterized in that: In all the robot's posture modes, if the robot does not need to float or dive, only the four tilted propellers are in operation, and the four tilted propellers always maintain the tilted position; The method for determining the attitude of each propeller thruster specifically includes: (1) Posture determination based on the rotation angle of the servo: In a multimodal underwater inspection robot, the posture of each propeller is directly controlled by the rotation angle of the corresponding servo. The system determines the current posture of the propeller through the following steps: Step A: The main controller reads the rotation angle of each servo in real time and compares it with the preset "horizontal posture" and "tilt posture" angle ranges; Horizontal attitude determination: When the servo rotation angle is at 0°±5°, the corresponding propeller is determined to be in a horizontal state; Tilt attitude determination: When the servo rotation angle is at 45°±5°, the corresponding propeller is determined to be in a tilted state; Step B: The main controller dynamically updates the propeller attitude database based on the servo angle information and marks the current state of each propeller; (2) Attitude assisted calibration based on the inertial measurement unit (IMU), specifically: The robot uses the onboard IMU to monitor the robot's overall posture data in real time; When there is a conflict between the servo angle and the robot attitude data fed back by the IMU, the robot system triggers a self-check program and prioritizes calibrating the actual thruster attitude with the IMU data; The method for determining the robot's propulsion direction in the motion coordinate system is as follows: (1) Modeling of thrust direction of propeller: The thrust direction of each thruster is determined by its installation position and the servo rotation angle: Horizontal thruster: The thrust direction is parallel to the axis of the robot body, in the X-axis direction, and is used for ascent / descent. Tilt thruster: The thrust direction is at a 45° angle to the axis of the robot body, with both Y-axis and Z-axis components coexisting, and is used for horizontal propulsion or auxiliary posture adjustment; (2) Thrust synthesis in the motion coordinate system The main controller performs the following operations based on the target motion instruction and the current thruster attitude data: Step A: Retrieve the thruster status from the attitude database, including level / tilt; Step B: Select the currently available propeller thruster group, divided into a horizontal group or a tilt group, as the power source; Step C: Based on the thrust vector model, calculate the direction and magnitude of the resultant force of the selected thruster group to ensure that the resultant force direction is consistent with the target motion direction; Step D: Dynamically adjust the speed of each propeller through PWM signals to achieve precise motion control; When the robot is working, the thruster working state is controlled by the following time-sharing control strategy method: Attitude adjustment stage: When the servo executes mode switching, the propeller thrusters suspend working to prevent the propeller thrust from interfering with the joint attitude adjustment process. Movement execution phase: After the servo angle is locked, the propeller thrusters restart according to the target command to ensure that the thrust direction matches the current attitude.

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