A deep-sea fish mouth-imitation underwater robot and its control method

Abstract

The present invention belongs to the technical field of underwater operation robots and specifically discloses a deep-sea fish-mouth-like underwater robot and its control method, wherein the underwater robot includes a robot body, which is used to provide a power source; a mounted collector, which is connected to the robot body via a mounting surface; wherein the mounted collector includes a fish-mouth upper jaw assembly, a fish-mouth lower jaw, a collection chamber, and a drive assembly; the fish-mouth upper jaw assembly includes an upper jaw body, a fixed joint, and a movable joint; during the pitching movement of the underwater robot, the drive assembly drives the movable joint to slide, the upper jaw body approaches or moves away from the fish-mouth lower jaw, and the mounted collector switches between a closed-mouth state and an open-mouth state to complete the mining operation. The present invention can operate efficiently without the need for additional motor drive, can realize multi-sample collection, and significantly improves the shortcomings of traditional underwater grabbing mining manipulators in terms of operational flexibility and energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater operation robots, and in particular to a deep-sea fish mouth imitating underwater robot and a control method thereof. Background Art

[0002] Deep-sea mining has garnered widespread attention as a key area of ​​future resource development. Seafloor deposits, the target of deep-sea mining, are among Earth's richest troves of mineral resources, harboring metal raw materials vital to modern industry. Polymetallic nodules, the most common type of seafloor deposit, are typically spherical or ellipsoidal, ranging in diameter from 1 to 12 centimeters. They are rich in manganese, nickel, copper, cobalt, and other metals. These nodules are widely distributed across the abyssal plains, offering significant mining potential.

[0003] Traditional deep-sea mining equipment has a significant impact on the seabed environment and consumes a lot of energy. This is primarily due to a long-standing bias in the deep-sea mining field against heavy machinery and high-energy-consuming technologies. The belief is that only powerful mechanical force and energy support can ensure equipment efficiency and reliability, while lightweight or biomimetic equipment cannot meet the complex demands of the deep-sea environment. Furthermore, traditional robot-arm coupling systems are complex in structure, and few are designed for specific workloads, such as deep-sea mining.

[0004] Research on underwater manipulators has progressed from two-degree-of-freedom to multi-degree-of-freedom designs, achieving diverse operational capabilities through the modeling and optimization of underactuated and rigid-flexible structures. However, these designs still have limitations. Many manipulators fail to fully consider the dynamic coupling characteristics of the underwater environment. Furthermore, manipulators primarily focused on grasping often suffer from high energy consumption, can only collect a single object at a time, and exhibit poor environmental performance.

[0005] In summary, it is now necessary to design an underwater robot mounted collector that imitates the mouth of a deep-sea fish and a control method thereof to solve the above-mentioned problems in the prior art. Summary of the Invention

[0006] The present invention provides a deep-sea fish-mouth-like underwater robot and a control method thereof, which overcomes the technical prejudice that light bionic equipment cannot meet the requirements of seabed mining.

[0007] In order to achieve the purpose of solving the above technical problems, the present invention adopts the following technical solutions:

[0008] An underwater robot imitating a deep-sea fish mouth, comprising:

[0009] A robot body, which is used to provide a power source;

[0010] A mounting collector connected to the robot body via a mounting surface;

[0011] The mounted collector includes a fish mouth upper jaw component, a fish mouth lower jaw, a collection cabin and a drive component;

[0012] The fish mouth upper jaw assembly includes an upper jaw body, a fixed joint and a movable joint; the upper jaw body is connected to the mounting surface via the fixed joint; the upper jaw body is connected to the driving assembly via the movable joint;

[0013] The driving assembly includes a driving counterweight and a driving connecting rod, wherein the driving counterweight is connected to the collection cabin via a driving joint shaft; one end of the driving connecting rod is connected to the driving counterweight, and the other end is connected to the movable joint;

[0014] During the pitching motion of the underwater robot, the driving assembly drives the movable joint to slide, the upper jaw body approaches or moves away from the fish mouth lower jaw, and the mounted collector switches between the closed mouth state and the open mouth state to complete the mining action.

[0015] In some embodiments of the present invention, the upper jaw body includes a top plate, a first side plate and a second side plate, wherein the first side plate and the second side plate are symmetrically arranged on both sides of the top plate; the first side plate and the second side plate are triangular plate structures with the same structure; the top angle of the triangular plate structure is a fixed point for setting the fixed joint; one of the bottom angles of the triangular plate structure is a rotation point for setting the movable joint, and the other bottom angle is used to contact the lower jaw of the fish mouth when the mounted collector is in a closed mouth state.

[0016] In some embodiments of the present invention, when the underwater robot performs a diving motion, the rotation point can rotate around the fixed point under the push of the driving assembly, the upper jaw body moves away from the fish mouth lower jaw, and the mounted collector enters an open mouth state;

[0017] When the underwater robot performs an upward movement, the rotation point can rotate around the fixed point under the pull of the driving component, the upper jaw body approaches the lower jaw of the fish mouth, and the mounted collector enters a closed mouth state.

[0018] In some embodiments of the present invention, the fish mouth upper jaw assembly also includes a baffle, which includes a connecting end and a free end, the connecting end is connected to the top plate and can rotate relative to the top plate; the free end is in contact with the fish mouth lower jaw.

[0019] In some embodiments of the present invention, the drive assembly and the maxillary body form a double rocker mechanism, and the output angle of the double rocker mechanism is the opening angle of the maxillary body; the output angle is obtained by the following formula:

[0020] ;

[0021] ;

[0022] ;

[0023] ;

[0024] Among them, φ1 is the rotation angle of the driving counterweight, φ3 is the output angle; U, V, and W are all intermediate variables, a is the length of the active rod of the double rocker mechanism, b is the length of the middle link of the double rocker mechanism, c is the length of the driven rod of the double rocker mechanism, and d is the length of the base of the double rocker mechanism.

[0025] In some embodiments of the present invention, the driving counterweight is located on both sides of the collection cabin; the driving counterweight is a nearly fan-shaped structure, and the driving joint axis is located at the center of the nearly fan-shaped structure; the driving connecting rod is connected to the end points of the nearly fan-shaped structure; during the pitching motion of the underwater robot, the driving counterweight rotates around the driving joint axis to drive the driving connecting rod to transmit.

[0026] In some embodiments of the present invention, a control method for a deep-sea fish mouth-like underwater robot is provided, comprising the following steps:

[0027] S1. Use sensors to collect water flow velocity, calculate water resistance parameters based on the water flow velocity and the movement speed of the underwater robot, and obtain a real-time water resistance matrix;

[0028] S2. updating the dynamic model of the robot body-mounted collector coupling system according to the real-time water resistance matrix;

[0029] S3. Calculate the actual control law of the dynamic model using the LQR method to obtain corresponding control instructions;

[0030] S4. The robot body adjusts the state variables of the coupling system to reach a desired state according to the control instructions.

[0031] In some embodiments of the present invention, step S3 specifically includes the following steps:

[0032] S31, determining the state variables of the underwater robot;

[0033] S32, linearize the system matrix and the input matrix;

[0034] S33, setting the weight matrix and calculating the optimal cost matrix;

[0035] S34, use the above matrix to solve the feedback gain K, and then determine the actual control law ;

[0036] in, is the driving force of the pitch motion of the robot body, is the state variable of the underwater robot.

[0037] In some embodiments of the present invention, the state variable for:

[0038] ,

[0039] x is the displacement of the underwater robot in the X direction, is the speed of the underwater robot in the X direction, z is the displacement of the underwater robot in the Z direction, is the speed of the underwater robot in the Z direction, θ1 is the rotation angle of the robot body around the Y axis, is the angular velocity of the robot body around the Y axis, θ2 is the rotation angle of the driving counterweight around the Y axis, is the angular velocity of the counterweight rotating around the Y axis.

[0040] In some embodiments of the present invention, the water resistance parameters in step S1 include: the water resistance of the underwater robot in the X-axis direction, the water resistance of the underwater robot in the Z-axis direction, the water resistance of the underwater robot rotating around the Y-axis, and the water resistance coupled to the driving link by the dynamic relationship of the double rocker mechanism.

[0041] The technical solution of the present invention has the following technical effects compared with the prior art:

[0042] The underwater robotic collector designed in this invention utilizes a large opening and closing structure that mimics the mouth of a deep-sea fish. Combining the advantages of a bucket and a robotic arm, the collector is driven by the pitch motion of the robot body. Incorporating the LQR control method, this demonstrates the feasibility of a lightweight design, enabling efficient operation without the need for additional motors and the collection of multiple samples. This significantly improves the operational flexibility and energy consumption deficiencies of traditional underwater grab-type mining robotic arms, enabling more efficient mining operations. The device can efficiently collect seafloor minerals, such as ferromanganese alloy nuclei, ranging in size from 8 to 14 centimeters, and is widely applicable to deep-sea mining, deep-sea sand mining, and other marine resource development and environmental monitoring projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 This is a structural schematic diagram of the deep-sea fish mouth imitating underwater robot in a closed state.

[0045] Figure 2 This is a structural schematic diagram of the deep-sea fish mouth imitating underwater robot in the open state.

[0046] Figure 3 This is a structural diagram of the mounted collector.

[0047] Figure 4 Schematic diagram of the cross-sectional structure of the mounted collector.

[0048] Figure 5 Schematic diagram of the structure of the maxillary body.

[0049] Figure 6 The motion diagram of the double rocker mechanism is shown in FIG. Figure 1 .

[0050] Figure 7 The motion diagram of the double rocker mechanism is shown in FIG. Figure 2 .

[0051] Figure 8 This is a simplified schematic diagram of the robot body-mounted collector coupling system.

[0052] Figure 9 This is a graph showing the changes in θ1 and θ2 during the process of starting the mounted collector.

[0053] Figure 10 This is a graph showing the changes in θ1 and θ2 during the closing process of the mounted collector.

[0054] Figure numerals: 100, robot body; 200, mounted collector; 210, fish mouth upper jaw assembly; 211, upper jaw body; 212, fixed joint; 213, movable joint; 214, top plate; 215, first side plate; 216, second side plate; 220, fish mouth lower jaw; 230, collection cabin; 231, mounting surface; 232, through hole; 241, driving counterweight; 242, driving connecting rod; 243, driving joint shaft; 250, baffle. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections. A person of ordinary skill in the art will understand the specific meanings of the above terms in the present invention in specific circumstances. In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any appropriate manner in any one or more embodiments or examples.

[0057] The deep-sea mining industry has long harbored a bias against heavy machinery and high-energy-consuming technologies, believing that only powerful mechanical forces and energy support can ensure equipment efficiency and reliability. This perception has led to skepticism about lightweight or biomimetic designs, believing they are unable to meet the complex demands of the deep-sea environment.

[0058] Furthermore, research on underwater manipulators has progressed from designs with two to multiple degrees of freedom. This has enabled diverse operational capabilities through the modeling and optimization of underactuated and rigid-flexible structures. For example, some have developed underwater vehicle systems equipped with dual manipulators, enabling dual-arm acquisition motions under dynamic coupling. Others have designed three- and six-degree-of-freedom manipulator systems for operations in diverse environments. However, these designs still have limitations. Many manipulators fail to fully consider the dynamic coupling characteristics of the underwater environment. Furthermore, manipulators primarily focused on grasping often suffer from high energy consumption and can only acquire a single object at a time, resulting in poor environmental performance.

[0059] This invention analyzes the mouth structure of deep-sea fish based on their main feeding movements; designs a dual-rocker structure to mimic the mouth structure of deep-sea fish, thereby mimicking the feeding movements of anglerfish for mining. The specific scheme is as follows:

[0060] Example 1: Reference Figure 1 and Figure 2 As shown, an underwater robot imitating a deep-sea fish mouth comprises:

[0061] The robot body 100 is used to provide a power source;

[0062] The mounting collector 200 is connected to the robot body 100 via the mounting surface 231;

[0063] The mounted collector 200 includes a fish mouth upper jaw component 210, a fish mouth lower jaw 220, a collection cabin 230 and a driving component;

[0064] The fish mouth upper jaw assembly 210 includes an upper jaw body 211, a fixed joint 212 and a movable joint 213; the upper jaw body 211 is connected to the mounting surface 231 via the fixed joint 212; the upper jaw body 211 is connected to the driving assembly via the movable joint 213;

[0065] The driving assembly includes a driving counterweight 241 and a driving connecting rod 242. The driving counterweight 241 is connected to the collection chamber 230 via a driving joint shaft 243. One end of the driving connecting rod 242 is connected to the driving counterweight 241, and the other end is connected to the movable joint 213.

[0066] During the pitching motion of the underwater robot, the driving assembly drives the movable joint 213 to slide, the upper jaw body 211 approaches or moves away from the fish mouth lower jaw 220, and the mounted collector 200 switches between the closed mouth state and the open mouth state to complete the mining action.

[0067] Specifically, the robot body 100 is fixedly connected to the mounting surface 231 located on the top of the mounting collector 200, so that the robot body 100 can drive the mounting collector 200 to perform pitching motion synchronously when performing pitching motion, thereby realizing the mouth opening and closing motions.

[0068] In some embodiments of the present invention, reference Figure 3 and Figure 4 As shown, the fish mouth upper jaw component 210 and the fish mouth lower jaw 220 are arranged opposite to each other, and are both located at the end of the collection chamber 230.

[0069] Specifically, the collection chamber 230 is a semi-enclosed structure consisting of a bottom surface, two side surfaces, a rear end surface and a mounting surface 231. The collection chamber 230 can temporarily place ores and other materials collected by the fish mouth structure.

[0070] The fish mouth lower jaw 220 is fixedly connected to the bottom surface of the collection chamber 230. The fish mouth lower jaw 220 has a downwardly concave arc and is used for collecting and gathering materials.

[0071] Continue to refer to Figure 3 As shown, for the fish mouth upper jaw component 210, its upper jaw body 211 is connected to the end of the mounting surface 231 through the fixed joint 212, so that the upper jaw body 211 can rotate relative to the mounting surface 231, but cannot produce displacement in any direction relative to the mounting surface 231.

[0072] The upper jaw body 211 is connected to the two side surfaces of the collection chamber 230 through the movable joint 213. Specifically, both side surfaces are provided with symmetrical through holes 232, which are in the shape of long strips. The movable joint 213 slides in the through holes 232, thereby driving the upper jaw body 211 to approach or move away from the fish mouth lower jaw 220.

[0073] In some embodiments of the present invention, reference Figure 5As shown, the upper jaw body 211 includes a top plate 214, a first side plate 215 and a second side plate 216, wherein the first side plate 215 and the second side plate 216 are symmetrically arranged on both sides of the top plate 214; the first side plate 215 and the second side plate 216 are triangular plate structures with the same structure; the top angle of the triangular plate structure is a fixed point for setting the fixed joint 212; one of the bottom angles of the triangular plate structure is a rotation point for setting the movable joint 213, and the other bottom angle is used to contact the fish mouth lower jaw 220 when the mounted collector 200 is in a closed mouth state.

[0074] In some embodiments of the present invention, when the underwater robot performs a diving motion, the rotation point can rotate around the fixed point under the push of the driving assembly, the upper jaw body 211 moves away from the fish mouth lower jaw 220, and the mounted collector 200 enters the open mouth state;

[0075] When the underwater robot performs an upward movement, the rotation point can rotate around the fixed point under the pull of the driving component, the upper jaw body 211 approaches the fish mouth lower jaw 220, and the mounted collector 200 enters a closed mouth state.

[0076] In some embodiments of the present invention, continue to refer to Figure 4 As shown, the fish mouth upper jaw assembly 210 further includes a baffle 250, which includes a connecting end and a free end. The connecting end is connected to the top plate 214 and can rotate relative to the top plate 214; the free end contacts the fish mouth lower jaw 220. The provision of the baffle 250 allows collected material to enter the collection chamber 230 in a single direction, thereby preventing material from leaking from the collection chamber 230 when the mouth is open.

[0077] In some embodiments of the present invention, continue to refer to Figure 4 As shown, in order to match the two side plate structures of the upper jaw body 211, the drive components are also arranged in two symmetrical groups, and the drive components are arranged on the two inner walls of the collection chamber 230. Specifically, the drive counterweight body 241 has a nearly fan-shaped structure, and the drive joint shaft 243 is located at the center of the nearly fan-shaped structure; the drive connecting rod 242 is connected to the end points of the nearly fan-shaped structure; during the pitch movement of the underwater robot, the drive counterweight body 241 rotates around the drive joint shaft 243 to drive the drive connecting rod 242. That is, the drive connecting rod 242 is used to connect the power source and the driven part, providing the driving force for the opening and closing of the fish mouth.

[0078] The invention analyzes the mouth structure of deep-sea fish (huge jaws and wide opening) based on their main feeding movements (the robot drives the collector to dive downward, and the upper jaw rotates counterclockwise and pushes outward, forming a bucket-like structure to "scoop" food into the mouth). It designs a double rocker structure to imitate the mouth structure of deep-sea fish, so as to imitate the feeding movements of anglerfish for mining.

[0079] In some embodiments of the present invention, reference Figure 6 and Figure 7 As shown, the drive assembly and the maxillary body 211 form a double rocker mechanism. Specifically, the active rod length of the double rocker mechanism is the distance between the drive joint axis point A and the connection point B of the drive link 242 on the drive counterweight body 241, the middle link length of the double rocker mechanism is the length of the drive link 242, the driven rod length of the double rocker mechanism is the distance between the movable joint point C and the fixed joint point D, and the base length of the double rocker mechanism is the distance between the drive joint axis point A and the fixed joint point D.

[0080] For this double rocker mechanism, the driving link 242 and the maxillary body 211 are made of lightweight materials, and their mass is much smaller than that of the driving counterweight 241. The inertia of the driving link 242 and the maxillary body 211 is ignored, and the model is simplified; the friction between the rotating joints of the double rocker mechanism is small, and the influence of joint friction is ignored.

[0081] The output angle of the double rocker mechanism is the opening angle of the maxillary body 211; the output angle is obtained by the following formula:

[0082] ;

[0083] ;

[0084] ;

[0085] ;

[0086] Among them, φ1 is the rotation angle of the driving counterweight 241, φ3 is the output angle; U is the intermediate variable 1, V is the intermediate variable 2, W is the intermediate variable 3, a is the active rod length of the double rocker mechanism, b is the middle connecting rod length of the double rocker mechanism, c is the driven rod length of the double rocker mechanism, and d is the base length of the double rocker mechanism.

[0087] The relationship between the angular velocities is:

[0088] ;

[0089] ;

[0090] Where, for The angular velocity, for The angular velocity, for angular velocity.

[0091] The relationship between the angular accelerations is:

[0092] ;

[0093] ;

[0094] Where, for The angular acceleration of for angular acceleration.

[0095] Figure 6 This is a structural diagram of the double rocker mechanism in the closed mouth state of the fish mouth. When the robot body performs a dive action, the driving counterweight 241 generates a clockwise driving torque. After the transmission of the driving connecting rod 242, the upper jaw body 211 has a counterclockwise output torque, thereby about to perform a mouth opening action.

[0096] Figure 7 This is a structural diagram of the double rocker mechanism in the open mouth state of the fish mouth. When the robot body performs an upward tilt movement, the driving counterweight 241 generates a counterclockwise restoring torque. After being transmitted by the driving connecting rod 242, the upper jaw body 211 has a clockwise output torque, thereby about to perform a mouth closing movement.

[0097] The technical solution of the present invention has the following technical effects compared with the prior art:

[0098] The present invention utilizes the feeding movement characteristics of the deep-sea fish's head to achieve more efficient collection movements; it only relies on the robot's gravity and restoring torque to work, does not require additional motors, has no additional energy consumption, and has excellent environmental benefits; it can efficiently develop marine resources, has low cost, environmental protection advantages and excellent working performance.

[0099] Example 2: A control method for a deep-sea fish mouth-like underwater robot is provided, comprising the following steps:

[0100] S1. Use sensors to collect water flow velocity, combine the water flow velocity and the movement speed of the underwater robot to calculate the water resistance parameters and obtain the water resistance matrix.

[0101] Specifically, they first used fluid dynamics simulation software to simulate the underwater robot's motion under different water flow velocities, obtaining scattered data on water resistance, water flow velocity, and motion speed. They then fitted the data to obtain a functional relationship between water resistance, water flow velocity, and motion speed. This functional relationship was then built into the underwater robot's main control board.

[0102] During actual operation, an underwater robot uses sensors to collect real-time water velocity in its ocean environment. These sensors are typically Doppler velocimeters. The robot's velocity is typically acquired through inertial sensors. Once equipped with these sensors, the robot can receive this data through the host computer's network serial port.

[0103] Then substitute the real-time water flow velocity and the current movement speed into the functional relationship to obtain the corresponding water resistance parameters.

[0104] The water resistance parameters include: the water resistance d1 of the underwater robot in the X-axis direction, the water resistance d2 of the underwater robot in the Z-axis direction, the water resistance d3 of the underwater robot rotating around the Y-axis, and the water resistance d4 coupled to the driving link by the dynamic relationship of the double rocker mechanism.

[0105] The obtained real-time water resistance matrix Di is:

[0106] .

[0107] S2. Update the dynamic model of the robot body-mounted collector coupling system according to the real-time water resistance matrix.

[0108] Reference Figure 8 The figure shows a simplified diagram of the robot-collector system. The inertial coordinate system is point O (0, 0, 0) of the water base station coordinate system, and point G of the body coordinate system is at the center of gravity of the robot. The collector is similar to a two-link under-actuated robotic arm. The joint of link 1 coincides with point G and is fixed, that is, link 1 is rigidly connected and cannot move; joint A of link 2 can only rotate around the Y axis and has only one degree of freedom.

[0109] The working principle of the mounted collector is to move by relying on the inertial force generated by the robot's own pitch motion (rotation around the Y-axis of point G) and the gravity of the connecting rod 2 itself. As the robot rotates around the Y-axis of point G to the lower rotation limit position, the connecting rod 2 will swing downward clockwise due to the action of inertia and gravity. When the robot rotates around the Y-axis of point G to the upper rotation limit position, the connecting rod 2 will swing from top to bottom due to the action of inertia and gravity.

[0110] The dynamic model of the robot body-mounted collector coupling system established based on the Lagrangian method is:

[0111] ;

[0112] Among them, M is the inertial mass matrix, C is the Coriolis force and centrifugal force matrix, G is the gravitational potential energy matrix, and Di is the real-time water resistance matrix.

[0113] The updated dynamic model will be involved in the calculation of the actual control law.

[0114] The specific process of establishing the dynamic model is as follows:

[0115] Step 1: Calculate the speed and angular velocity of the robot body and the driving counterweight;

[0116] First, we characterize the generalized position vector of the robot-collector and the generalized velocity vector :

[0117] ;

[0118] ;

[0119] Where x is the displacement of the robot body in the X direction, z is the displacement of the robot body in the Z direction, θ1 is the rotation angle (pitch angle) of the robot body around the Y axis, and θ2 is the rotation angle of the driving counterweight around the Y axis;

[0120] is the speed of the robot body in the X direction, is the speed of the robot body in the Z direction, is the angular velocity of the robot body around the Y axis, is the angular velocity that drives the counterweight to rotate around the Y axis.

[0121] Then determine the center of gravity p of the robot body c1 and the center of gravity p of the driving counterweight c2 ;exist Figure 8 In the figure, the center of gravity of the robot body p c1 Coincident with the origin O of the coordinate system:

[0122] ;

[0123] ;

[0124] Among them, l c1 is the distance from the robot body's rotation center to its center of gravity, l c1 =0, that is, the rotation center of the robot body coincides with the center of gravity; l c2is the length from the rotation center of the driving counterweight to the center of gravity; l1 is the distance from the center of gravity of the robot body to the rotation center of the driving counterweight; l2 is the length between the rotation center of the driving counterweight and the driving joint axis; q1 is the center of gravity offset angle of the robot body; q2 is the center of gravity offset angle of the driving counterweight.

[0125] Calculate the velocity and angular velocity of the robot body and the driving counterweight:

[0126] ;

[0127] Among them, v1 is the speed of the robot body; v2 is the speed of the driving counterweight; ω1 is the angular velocity of the robot body; ω2 is the angular velocity of the driving counterweight.

[0128] Step 2: Use the Lagrangian method to calculate the inertial mass matrix of the robot-collector, solve the Coriolis force and centrifugal force matrix, the gravitational potential energy matrix and the water resistance matrix.

[0129] First, calculate the overall kinetic energy Wt of the robot-collector:

[0130] ;

[0131] Wherein, m1 is the mass of the robot body; m2 is the mass of the driving counterweight; M RB is the rigid body inertia mass matrix; I1 is the moment of inertia of the robot body; I2 is the moment of inertia of the driving counterweight.

[0132] Then calculate the additional mass matrix:

[0133] .

[0134] According to formulas (1)-(7), the calculation formula for the inertial mass matrix M of the robot-collector can be obtained as follows:

[0135] ;

[0136] in, ;

[0137] ;

[0138] ;

[0139] ;

[0140] ;

[0141] ;

[0142] ;

[0143] ;

[0144] ;

[0145] .

[0146] According to Christoffel notation, we have formula (9):

[0147] .

[0148] According to formulas (8) and (9), the Coriolis force and centrifugal force matrix C can be obtained:

[0149] ;

[0150] in:

[0151] ;

[0152] ;

[0153] ;

[0154] ;

[0155] .

[0156] Gravitational potential energy is defined as:

[0157] ;

[0158] ;

[0159] .

[0160] Calculate the gravitational potential energy matrix G:

[0161] ;

[0162] in, ;

[0163] ;

[0164] ;

[0165] .

[0166] The water resistance matrix D is obtained in step S1.

[0167] S3, using the LQR method to calculate the actual control law of the dynamic model to obtain the corresponding control instructions; specifically comprising the following steps:

[0168] S31, determining the state variables of the underwater robot ;

[0169] The state variables of the underwater robot , x is the displacement of the underwater robot in the X direction, is the speed of the underwater robot in the X direction, z is the displacement of the underwater robot in the Z direction, is the speed of the underwater robot in the Z direction, θ1 is the rotation angle of the robot body around the Y axis, is the angular velocity of the robot body around the Y axis, θ2 is the rotation angle of the driving counterweight around the Y axis, is the angular velocity of the counterweight rotating around the Y axis.

[0170] According to the state variables of the underwater robot, its derivative can be obtained as follows:

[0171] ;

[0172] Combining formula (12) with the updated dynamic model, we can obtain:

[0173] .

[0174] S32, linearizing the system matrix A and the input matrix B;

[0175] Determine the output force and torque vector τ: ;

[0176] Among them, f x is the resultant force of the thruster in the X direction; f z is the resultant force of the propeller in the Z direction; τ1 is the torque generated by the propeller around the Y axis.

[0177] Specifically, the calculation formula of the system matrix A is: ;

[0178] Input matrix B calculation formula: .

[0179] S33, setting the weight matrix and calculating the optimal cost matrix;

[0180] According to the above calculation results, the state equation is obtained: .

[0181] Set the values ​​of the weight matrix Q and R, which control the state accuracy and energy respectively:

[0182] ;

[0183] .

[0184] S34, use the above matrix to solve the feedback gain K, and then determine the actual control law .

[0185] Solving the Riccati equation for continuous systems

[0186] .

[0187] The calculation formula of feedback gain K is as follows:

[0188] .

[0189] After obtaining the optimal solution of K and P, the actual control law is finally determined .

[0190] The LQR control algorithm used in this embodiment obtains It is the driving force for the pitching motion of the robot body. Specifically, the driving force is the aggregation of multiple driving forces of multiple motors of the underwater robot.

[0191] That is, the actual control law output is the control instruction of the driving force of multiple motors of the underwater robot.

[0192] S4. The robot body adjusts the state variables of the robot body-mounted collector coupling system according to the control instructions. Reach the desired state.

[0193] The robot body adjusts the driving force of each motor according to the control instruction, thereby adjusting the state variables of the underwater robot to reach the desired state.

[0194] Using the control method in this embodiment, good control effect can be obtained. Figure 9 and Figure 10 As shown: the purple line is the robot body pitch angle θ1, and the pink line is the collector drive block working angle θ2. Figure 9 In the opening process shown, the collector is turned on, and it can be seen that θ1 decreases and then increases, indicating that the robot returns to the horizontal after rotating clockwise around the Y axis, and the angle θ2 decreases and then remains horizontal, indicating that the collector is turned on. Figure 10 During the power-on process shown, it can be seen that θ1 increases and then decreases, indicating that the robot rotates counterclockwise around the Y axis and then returns to a horizontal position. The angle θ2 increases and then remains horizontal, indicating that the collector is turned off.

[0195] The main control board involved in this embodiment is responsible for receiving and processing data from various sub-functional modules and outputting corresponding control signals based on sensor feedback and operational instructions. This allows for motion control, status monitoring, task instruction transmission, and inter-system data communication. The main control hardware system is centered around a microcontroller unit (MCU), equipped with multiple communication interfaces for interacting with external devices, and implements signal processing and control through multiple circuit modules.

[0196] The technical solution of the present invention has the following technical effects compared with the prior art:

[0197] The underwater robotic collector designed in this invention utilizes a large opening and closing structure that mimics the mouth of a deep-sea fish. Combining the advantages of a bucket and a robotic arm, the collector is driven by the pitch motion of the robot body. Incorporating the LQR control method, this demonstrates the feasibility of a lightweight design, enabling efficient operation without the need for additional motors and the collection of multiple samples. This significantly improves the operational flexibility and energy consumption deficiencies of traditional underwater grab-type mining robotic arms, enabling more efficient mining operations. The device can efficiently collect seafloor minerals, such as ferromanganese alloy nuclei, ranging in size from 8 to 14 centimeters, and is widely applicable to deep-sea mining, deep-sea sand mining, and other marine resource development and environmental monitoring projects.

[0198] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0199] The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A control method for a deep-sea fish-mouth-like underwater robot, characterized in that: The deep-sea fish mouth imitation underwater robot comprises: A robot body, which is used to provide a power source; A mounting collector connected to the robot body via a mounting surface; The mounted collector includes a fish mouth upper jaw component, a fish mouth lower jaw, a collection cabin and a drive component; The fish mouth upper jaw assembly includes an upper jaw body, a fixed joint and a movable joint; the upper jaw body is connected to the mounting surface via the fixed joint; the upper jaw body is connected to the driving assembly via the movable joint; The driving assembly includes a driving counterweight and a driving connecting rod, wherein the driving counterweight is connected to the collection cabin via a driving joint shaft; one end of the driving connecting rod is connected to the driving counterweight, and the other end is connected to the movable joint; During the pitching motion of the underwater robot, the driving assembly drives the movable joint to slide, the upper jaw body moves closer to or away from the fish mouth lower jaw, and the mounted collector switches between the closed mouth state and the open mouth state to complete the mining action; The control method of the deep-sea fish mouth-simulating underwater robot comprises the following steps: S1. Use sensors to collect water flow velocity, calculate water resistance parameters based on the water flow velocity and the movement speed of the underwater robot, and obtain a real-time water resistance matrix; S2. updating the dynamic model of the robot body-mounted collector coupling system according to the real-time water resistance matrix; S3. Calculate the actual control law of the dynamic model using the LQR method to obtain corresponding control instructions; S4. The robot body adjusts the state variables of the coupling system to reach a desired state according to the control instructions.

2. The control method of a deep-sea fish mouth underwater robot according to claim 1, characterized in that: The upper jaw body includes a top plate, a first side plate and a second side plate, wherein the first side plate and the second side plate are symmetrically arranged on both sides of the top plate; the first side plate and the second side plate are triangular plate structures with the same structure; the top angle of the triangular plate structure is a fixed point for setting the fixed joint; one of the bottom angles of the triangular plate structure is a rotation point for setting the movable joint, and the other bottom angle is used to contact the lower jaw of the fish mouth when the mounted collector is in the closed mouth state.

3. The control method of a deep-sea fish mouth underwater robot according to claim 2, characterized in that: When the underwater robot performs a diving motion, the rotating point can rotate around the fixed point under the push of the driving component, the upper jaw body moves away from the fish mouth lower jaw, and the mounted collector enters the open mouth state; When the underwater robot performs an upward movement, the rotation point can rotate around the fixed point under the pull of the driving component, the upper jaw body approaches the lower jaw of the fish mouth, and the mounted collector enters a closed mouth state.

4. The control method of a deep-sea fish mouth underwater robot according to claim 3, characterized in that: The fish mouth upper jaw component also includes a blocking piece, which includes a connecting end and a free end. The connecting end is connected to the top plate and can rotate relative to the top plate; the free end is in contact with the fish mouth lower jaw.

5. The control method of a deep-sea fish mouth underwater robot according to claim 3, characterized in that: The drive assembly and the maxillary body form a double rocker mechanism, and the output angle of the double rocker mechanism is the opening angle of the maxillary body; the output angle is obtained by the following formula: ； ； ； ； in, is the rotation angle of the driving counterweight, is the output angle; U, V, and W are all intermediate variables, a is the length of the active rod of the double rocker mechanism, b is the length of the middle connecting rod of the double rocker mechanism, c is the length of the driven rod of the double rocker mechanism, and d is the length of the base of the double rocker mechanism.

6. The control method of a deep-sea fish mouth underwater robot according to claim 1, characterized in that: The driving counterweight body is located on both sides of the collection cabin; the driving counterweight body is a nearly fan-shaped structure, and the driving joint axis is located at the center of the nearly fan-shaped structure; the driving connecting rod is connected to the end points of the nearly fan-shaped structure; during the pitching movement of the underwater robot, the driving counterweight body rotates around the driving joint axis to drive the driving connecting rod to transmit.

7. The control method of a deep-sea fish mouth underwater robot according to claim 1, characterized in that: The step S3 specifically includes the following steps: S41, determining the state variables of the underwater robot; S42, linearize the system matrix and the input matrix; S43, setting a weight matrix and calculating an optimal cost matrix; S44, using the above matrix to solve the feedback gain K, and then determine the actual control law; Among them, is the driving force of the pitch motion of the robot body, and is the state variable of the underwater robot.

8. The control method of a deep-sea fish mouth underwater robot according to claim 7, characterized in that: The state variables are: ； Where x is the displacement of the underwater robot in the X direction, is the speed of the underwater robot in the X direction, z is the displacement of the underwater robot in the Z direction, is the speed of the underwater robot in the Z direction, θ1 is the rotation angle of the robot body around the Y axis, is the angular velocity of the robot body around the Y axis, θ2 is the rotation angle of the driving counterweight around the Y axis, is the angular velocity of the counterweight rotating around the Y axis.

9. The control method of a deep-sea fish mouth underwater robot according to claim 1, characterized in that: The water resistance parameters in step S1 include: the water resistance of the underwater robot in the X-axis direction, the water resistance of the underwater robot in the Z-axis direction, the water resistance of the underwater robot rotating around the Y-axis, and the water resistance of the dual rocker mechanism coupled to the driving link by dynamics.

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