Spherical underwater robot with single group of propellers and hydrological monitoring equipment

Abstract

The invention belongs to the field of robots, and particularly relates to a spherical underwater robot with a single set of propellers and hydrological monitoring equipment. The underwater robot comprises a pressure-resistant shell, a propeller, a balance adjusting assembly, a gyroscope, a power source and a controller. The two propellers are symmetrically and fixedly installed on the two sides of the pressure-resistant shell. The balance adjusting assembly drives the robot to roll by adjusting the position of the mass center of the equipment, and then the thrust direction of the propeller is adjusted. The controller is electrically connected with the two driving motors and the propeller; on one hand, the controller can adjust the space posture of the robot by controlling the two driving motors; on the other hand, advancing, retreating or steering can be achieved by controlling the two propellers. On the basis, the driving motor and the propellers are cooperatively controlled, so that the underwater machine can realize complex actions by utilizing a single group of propellers. Therefore, the problem that the underwater robot needs to depend on multiple propellers to realize attitude adjustment and motion control is solved.

Description

Technical Field

[0001] The present invention belongs to the field of robots, and particularly relates to a spherical underwater robot with a single set of thrusters and its corresponding hydrological monitoring equipment. Background Art

[0002] Underwater robots are often used in fields such as underwater exploration or hydrological monitoring. Underwater robots can navigate underwater and complete various detection or sampling tasks. Existing underwater robots usually achieve attitude control through propellers or flywheels. In order to achieve more free navigation and attitude control, underwater robots often need to be equipped with thrusters in multiple directions, and steering or other actions are achieved through the combined thrust applied by different thrusters. However, more thrusters lead to complex device structures and high energy consumption, and increase the design difficulty of miniaturizing related devices. Therefore, how to improve the attitude adjustment accuracy and motion stability of underwater robots based on a simpler structure in complex underwater environments is becoming a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0003] In order to solve the problem that underwater robots need to rely on multiple thrusters to achieve attitude adjustment and motion control, the present invention provides a spherical underwater robot with a single set of thrusters and its corresponding hydrological monitoring equipment.

[0004] The technical solution provided by the present invention is as follows:

[0005] A spherical underwater robot with a single set of thrusters can achieve underwater navigation through the thrusters installed thereon. The underwater robot includes a spherical pressure-resistant shell, two thrusters, a balance adjustment component, a gyroscope, a power source, and a controller. Among them, the two thrusters are symmetrically and fixedly installed on both sides of the pressure-resistant shell; in the device coordinate system of the underwater robot in this embodiment, the connection direction of the two thrusters is the X-axis direction, and the thrust direction is the Y-axis direction. The gyroscope is fixed inside the pressure-resistant shell and is used to detect the spatial attitude of the underwater robot; the power source is located inside the pressure-resistant shell and is used to supply power to the underwater robot.

[0006] The balance adjustment component is fixedly connected to the inner cavity of the pressure-resistant shell; the balance adjustment component includes a fixed frame, a swing arm, a first driving motor, and a linear module. The swing arm is rotatably connected to the fixed frame; the first driving motor is installed on the fixed frame. The linear module is fixed on the swing arm, and the linear module includes a second driving motor, a lead screw, and a slide table as a counterweight. The first driving motor is used to drive the combination of the linear module and the swing arm to rotate relative to the fixed frame in the YOZ plane; the second driving motor drives the slide table to translate along the X-axis direction on the swing arm through the lead screw.

[0007] The controller is electrically connected to the first drive motor, the second drive motor and the two propellers; the controller includes a posture control unit, a motion control unit and a balance control table. The balance control table includes the rotation angle α of the first drive motor i The pitch angle θ of the thruster in the YOZ plane i The mapping relationship between them, and at any pitch angle θ i In the state, the displacement distance l of the slide along the X-axis direction j The yaw angle β of the thruster in the XOZ plane ij The mapping relationship between them. The attitude control unit is used to determine the real-time attitude of the underwater robot according to the detection results of the gyroscope in the suspended or moving state, and then query the balance control table to generate instructions for collaboratively controlling the first drive motor and the second drive motor, and then adjust the center of mass position of the underwater robot to drive it to achieve attitude adjustment, and finally reach the target attitude. The motion control unit is used to: (i) synchronously drive the two thrusters to operate to achieve forward or backward movement. (ii) When the thruster is in an inclined state, drive the two thrusters to operate synchronously to achieve floating or diving; (iii) When the thruster is in a horizontal state, differentially control the two thrusters to achieve steering.

[0008] As a further improvement of the present invention, the first drive motor is a servo motor or a stepper motor; the first drive motor is connected to the swing arm through a gear set or a coupling.

[0009] As a further improvement of the present invention, the fixing frame includes a long strip top plate and a plurality of supporting plates perpendicular to the top plate and parallel to each other. The first drive motor is hoisted below the top plate and fixed by the supporting plates. The output shaft of the first drive motor is parallel to the extension direction of the bottom plate of the fixing frame.

[0010] The swing arm is L-shaped, including a long strip bottom plate and a cantilever perpendicular to the bottom plate. A circular hole is provided at the end of the cantilever away from the bottom plate; the axial direction of the circular hole is parallel to the extension direction of the bottom plate; the swing arm is sleeved on the end of the output shaft of the first drive motor through the circular hole on it, and the two are rotatably connected through a bearing.

[0011] As a further improvement of the present invention, the output shaft of the first drive motor is drivingly connected to the swing arm through a planetary gear set. The planetary gear set includes: a first separator plate, a ring gear, a sun gear, planet gears, a planet carrier, a second separator plate, a first connecting rod, and a second connecting rod. Through holes are provided at the centers of the first separator plate and the second separator plate; the two are sleeved on the output shaft of the first drive motor through bearings; the first connecting rod fixedly connects the two on the opposite sides of the first separator plate and the second separator plate. Teeth are provided on the inner side of the ring gear, and the ring gear is fixed on one side of the first separator plate close to the second separator plate; the ring gear, the first separator plate, and the second separator plate are coaxially arranged; the outer diameter of the sun gear is smaller than the inner diameter of the ring gear; the sun gear is key-connected to the output shaft of the first drive motor and is located at the center of the ring gear; the planet gears are mounted on the output shaft through the planet carrier; the planet gears are both externally meshed with the sun gear and internally meshed with the ring gear, thereby realizing the driving connection between the two; one end of the second connecting rod is fixedly connected to the outer edge of the second separator plate, and the other end is fixedly connected to one side of the swing arm close to the bottom plate.

[0012] As a further improvement of the present invention, mounting holes are provided on the plate surface of the support plate, and the first drive motor is inserted into the mounting holes of two adjacent support plates for fixation.

[0013] Vertical plates perpendicular to the bottom plate are provided at both ends of the bottom plate in the swing arm, and both ends of the lead screw are rotatably connected to the vertical plates at both ends of the bottom plate through bearings.

[0014] As a further improvement of the present invention, the pressure-resistant shell is assembled by two hemispherical shells, and a sealing ring is provided at the contact surface between the two.

[0015] As a further improvement of the present invention, a circular partition plate is provided inside the pressure-resistant shell, and the partition plate divides the inner cavity of the pressure-resistant shell into an upper cavity and a lower cavity.

[0016] As a further improvement of the present invention, the power supply uses a rechargeable lithium battery, and the power supply is installed in the upper cavity; the balance adjustment assembly is installed in the lower cavity.

[0017] As a further improvement of the present invention, through holes are provided in the pressure-resistant shell, and portholes are provided at the through holes.

[0018] The underwater robot includes a camera, which is used to obtain an environmental image on one side corresponding to the forward direction outside the pressure-resistant shell through the porthole.

[0019] As a further improvement of the present invention, the underwater robot includes an ultrasonic radar, which is used to detect obstacles around the underwater robot.

[0020] As a further improvement of the present invention, the underwater robot includes a positioning module, which is used to perform real-time positioning on the underwater robot.

[0021] As a further improvement of the present invention, the underwater robot includes a depth sensor for detecting the depth information of the underwater robot.

[0022] As a further improvement of the present invention, the underwater robot includes a temperature and humidity sensor for detecting the temperature and humidity inside or outside the underwater robot.

[0023] As a further improvement of the present invention, the spherical underwater robot further includes a navigation module. The navigation module is used to generate a planned path based on the real-time position and the target position of the underwater robot; the planned path contains multiple path nodes, and the target state information of each path node includes the corresponding attitude information and power information. The navigation module is used to obtain the real-time state information of the underwater robot, and then generate the corresponding attitude adjustment amount and power control amount by combining the target state information corresponding to the current path node and the real-time state information; and then send them to the controller of the underwater robot.

[0024] As a further improvement of the present invention, the navigation module is further used to obtain the obstacle information collected by the ultrasonic radar and the camera, and adjust the planned path in real time according to the obstacle information.

[0025] The present invention further includes a hydrological monitoring device, which uses the spherical underwater robot with a single set of thrusters as described above as a vehicle; sensors or detection devices related to hydrological monitoring are also installed in the vehicle of the hydrological detection device.

[0026] The technical solution provided by the present invention has the following beneficial effects:

[0027] Although the spherical underwater robot provided by the present invention is only equipped with a single set of symmetric thrusters, through the balance adjustment component installed therein, the robot can freely adjust its own spatial attitude underwater. Combining the spatial pose and the switching of the thrust direction of the thrusters, the underwater robot of the present invention can perform various complex actions such as forward, backward, hovering, rotating, ascending and descending underwater. Compared with the existing single thruster or the propulsion system with limited directions, the present invention has better flexibility and adaptability, and the structure is simpler, which also lays a foundation for using it as a vehicle to carry various complex underwater detection devices.

[0028] The underwater robot provided by the present invention can adopt a modular design, so that each component can be repaired or replaced separately when damaged, reducing the overall maintenance cost. At the same time, the design of the closed spherical shell ensures that the robot has good pressure resistance and sealing performance, improving the reliability of the system when working underwater.

[0029] Combined with various detection devices and sensors carried, the underwater robot provided by the present invention can achieve more accurate state detection and environmental perception, and can utilize the detection results to achieve path planning, autonomous obstacle avoidance, and automatic navigation underwater, so as to further reduce the operation difficulty of the underwater robot. Combined with the control algorithm in the controller, the underwater robot can also quickly respond to external environmental changes and maintain stable postures. Especially in the case of complex water flows or the presence of obstacles, compared with traditional underwater robots, the present invention has a significant improvement in attitude stability. Description of the Drawings

[0030] Figure 1 It is an overall external view of the spherical underwater robot provided in Embodiment 1 of the present invention.

[0031] Figure 2 It is a perspective view of the spherical underwater robot provided in Embodiment 1 of the present invention.

[0032] Figure 3 It is a schematic structural diagram of the interior of the spherical underwater robot provided in Embodiment 1 of the present invention.

[0033] Figure 4 It is a schematic structural diagram of the balance adjustment assembly in Embodiment 1 of the present invention.

[0034] Figure 5 It is an assembly schematic diagram of the fixed frame and the swing arm in the balance adjustment assembly.

[0035] Figure 6 It is a structural assembly diagram of the swing arm and the linear module in the balance adjustment assembly.

[0036] Figure 7 It is a schematic structural diagram of the planetary gear set adopted in Embodiment 1 of the present invention.

[0037] Figure 8 It is an exploded view of the parts of the planetary gear set adopted in Embodiment 1 of the present invention.

[0038] Figure 9 It is an assembly schematic diagram of the ring gear, the sun gear, and the planet gear in the planetary gear set.

[0039] Figure 10 It is a state change diagram of the underwater robot achieving the diving action in Embodiment 1 of the present invention.

[0040] Figure 11 It is a flowchart of the underwater robot achieving the obstacle avoidance strategy in Embodiment 1 of the present invention.

[0041] The labels in the figure are:

[0042] 1. Pressure-resistant shell; 2. Thruster; 3. Power supply; 4. Balance adjustment assembly; 11. Partition board; 41. Fixing frame; 42. First drive motor; 43. Swing arm; 44. Planetary gear set; 45. Linear module; 411. Top plate; 412. Support plate; 421. Bottom plate; 422. Cantilever; 423. Vertical plate; 441. Coupling; 442. First partition disc; 443. Tooth ring; 444. Sun gear; 445. Planet gear; 446. Planet carrier; 447. Second partition disc; 448. First connecting rod; 449. Second connecting rod; 451. Lead screw; 452. Slide block; 453. Second drive motor. Detailed implementation manner

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] Embodiment 1

[0045] This embodiment provides a spherical underwater robot with a single set of thrusters 2. This underwater robot belongs to a diving robot. In the diving state, the buoyancy and gravity of the robot are balanced, so it can remain suspended after stopping. A balance chamber can also be provided in the underwater robot, and then the ballast water in the balance chamber can be increased or decreased to adjust the gravity of its own equipment, thereby realizing the adjustment of the draft depth. In addition, when the thruster 2 of this type of underwater robot operates, it can "roll" by adjusting its own center of mass position, thereby adjusting the thrust direction of the thruster 2 and realizing free underwater navigation.

[0046] Specifically, as Figure 1 and Figure 2As shown in the figure, the underwater robot includes a spherical pressure hull 1, two thrusters 2, a balance adjustment assembly 4, a gyroscope, a power supply 3, and a controller. The power supply 3 is located inside the pressure hull 1 and is used to power the underwater robot. Among them, the pressure hull 1 is assembled by two hemispherical hulls. In practical applications, the pressure hull 1 can be made of alloy materials or processed by FDM 3D printing technology using resin materials such as PLA+. For small devices, the two hemispherical hulls can be connected by trapezoidal threads. For larger spherical underwater robots, flange plates can be provided at the edges of the hemispherical hulls, and the two hemispherical hulls can be flange-connected. In order to make the assembled spherical hull have better sealing performance and durability, sealing rings are provided on the contact surfaces of the two hemispherical hulls in this embodiment. Through the design of the spherical pressure hull 1 in this embodiment, the fluid resistance suffered by the robot in water is small, and the resistance in all directions is uniform, which helps to reduce energy consumption and improve propulsion efficiency. In addition, through the ARV centroid adjustment, partial attitude control is realized, reducing the energy loss caused by simply relying on the thrusters, thereby increasing the underwater endurance time of the robot.

[0047] As Figure 3 shown, in the typical solution of this embodiment, a circular partition 11 is provided inside the pressure hull 1, and the partition 11 is installed in the upper spherical hull. The partition 11 in this embodiment divides the inner cavity of the pressure hull 1 into an upper cavity and a lower cavity. Among them, the space of the lower cavity is larger than that of the lower cavity. In this embodiment, the power supply 3 uses a rechargeable lithium battery, and the power supply 3 is installed in the upper cavity; the balance adjustment assembly 4 is installed in the lower cavity. In this embodiment, the power supply 3 and other electronic control devices are placed in two separate cavities to improve the safety of the device.

[0048] In the underwater robot provided in this embodiment, a mounting seat is symmetrically provided on each side of the spherical hull, and the two thrusters 2 are symmetrically and fixedly installed on both sides of the pressure hull 1 through the mounting seats. In the solution of this embodiment, each thruster 2 includes a nose and a propeller. Driven by the nose, the propeller can rotate forward and backward, thereby providing thrust in different directions for the underwater robot. In the solution of this embodiment, the two thrusters 2 are fixedly installed on the side of the pressure hull 1 and cannot rotate relative to each other. The thrust direction of the thruster 2 is tangent to the spherical surface of the pressure hull 1. As Figure 2 shown, in the device coordinate system of the underwater robot in this embodiment, the connection direction of the two thrusters 2 is the X-axis direction, and the thrust direction is the Y-axis direction. Based on this structure, when the two thrusters 2 are in a horizontal horizontal position, the spherical robot can only perform actions such as forward, backward, and turning on the current horizontal plane, and cannot perform diving or floating actions.

[0049] The balance adjustment component 4 of this embodiment is a controllable deformation mechanism, which serves as an adjustable "counterweight" in the underwater robot. The balance adjustment component 4 is fixedly connected to the inner cavity of the pressure-resistant shell 1. By adjusting the shape of the balance adjustment component 4, the position of the center of mass of the spherical underwater robot in the pressure-resistant shell 1 can be changed. At this time, when the center of mass position changes, in order to balance gravity and buoyancy again, the underwater robot will spontaneously roll over, thereby changing the spatial posture of the underwater robot and tilting the thrust direction of the two thrusters 2, so that the thrust of the thruster 2 can generate a component force in the vertical direction, thereby enabling the underwater robot to achieve actions such as diving and floating.

[0050] Specifically, Figure 4 As shown, the balance adjustment component 4 of this embodiment includes a fixed frame 41, a swing arm 43, a first drive motor 42 and a linear module 45. The swing arm 43 is rotatably connected to the fixed frame 41; the first drive motor 42 is installed on the fixed frame 41. The linear module 45 is fixed on the swing arm 43, and the linear module 45 includes a second drive motor 453, a lead screw 451 and a slide as a counterweight. The first drive motor 42 is used to drive the combination of the linear module 45 and the swing arm 43 to rotate in the YOZ plane relative to the fixed frame 41; the second drive motor 453 drives the slide to translate along the X-axis direction on the swing arm 43 through the lead screw 451.

[0051] In detail, the first drive motor 42 and the second drive motor 453 of the present embodiment are respectively used to more accurately control the rotation of the swing arm 43 and the translation of the slider 452. Therefore, both can adopt servo motors or stepper motors. Among them, in order to realize the rotation adjustment, the first drive motor 42 and the swing arm 43 can be transmitted through a gear set, or the output shaft of the drive motor can be directly connected to the swing arm 43 through a coupling 441, so that the swing arm 43 swings when the output shaft of the drive motor rotates.

[0052] In the typical solution provided in this embodiment, Figure 5 As shown, the fixing frame 41 includes a long strip-shaped top plate 411 and a plurality of support plates 412 perpendicular to the top plate 411 and parallel to each other. The first drive motor 42 is suspended below the top plate 411 and fixed by the support plates 412. The output shaft of the motor is parallel to the extension direction of the bottom plate 421 of the fixing frame 41. The fixing frame 41 of this embodiment includes a total of four support plates 412, wherein the plate surfaces of the two support plates 412 on the left are provided with mounting holes, and the body of the first drive motor 42 is inserted into the mounting holes of the two adjacent support plates 412 to achieve fixation. Bearings are respectively embedded and installed in the two support plates 412 on the right, and the output shaft of the first drive motor 42 passes through the inner rings of the bearings on the two support plates 412 to achieve rotatable connection with the fixing frame 41.

[0053] Combined with Figure 6 It can also be found that the swing arm 43 in the balance adjustment assembly 4 of this embodiment is L-shaped, including a long strip-shaped bottom plate 421 and a cantilever 422 perpendicular to the bottom plate 421. A round hole is provided at the end of the cantilever 422 on the side far from the bottom plate 421; the axial direction of the round hole is parallel to the extension direction of the bottom plate 421; the swing arm 43 is sleeved on the end of the output shaft of the first drive motor 42 through the round hole thereon, and the two are rotatably connected through a bearing. In Figure 5 In the assembled state shown, the first drive motor 42 still cannot directly drive the swing arm 43 to rotate relative to the fixed frame 41. In order to achieve control, this embodiment also transmits and connects the output shaft of the first drive motor 42 and the swing arm 43 through a planetary gear set 44.

[0054] Specifically, as Figure 7 and Figure 8 shown, the planetary gear set 44 adopted in this embodiment includes a first separator 442, a gear ring 443, a sun gear 444, a planetary gear 445, a planet carrier 446, a second separator 447, a first connecting rod 448 and a second connecting rod 449. Through holes are provided in the centers of the first separator 442 and the second separator 447; bearings are embedded in the through holes, and the inner rings of the bearings are sleeved on the output shaft of the first drive motor 42. In this embodiment, the first connecting rod 448 fixedly connects the first separator 442 and the second separator 447 along the opposite sides of the first separator 442 and the second separator 447. At this time, the first separator 442 and the second separator 447 form a whole, and the two can rotate with the output shaft of the electrode as the rotation axis. In practical applications, the combination formed by the first separator 442, the second separator 447 and the first connecting rod 448 can be assembled by split parts or directly by integral parts. Among them, the first connecting rod 448 can adopt a connecting pin or other connecting parts connecting the first separator 442 and the second separator 447, or can also adopt a ribbed structure processed integrally.

[0055] In this embodiment, the inner side of the gear ring 443 is provided with teeth, and the gear ring 443 is fixed on the side of the first separator 11 close to the second separator 11; among them, the gear ring 443, the first separator 442 and the second separator 447 are coaxially arranged. The three are located at different positions on the axial direction of the output shaft of the first drive motor 42. In this embodiment, the outer diameter of the sun gear 444 is smaller than the inner diameter of the gear ring 443; the sun gear 444 is key-connected to the output shaft of the first drive motor 42 through a coupling 441, and the sun gear 444 is located in the center of the gear ring 443; the planetary gear 445 is installed on the output shaft through the planet carrier 446; the planetary gear 445, the sun gear 444 and the gear ring 443 are located at the same position on the axial direction of the output shaft of the first drive motor 42, among which, as Figure 9As shown, the planet gear 445 is in external meshing with the sun gear 444 and internal meshing with the ring gear 443, thereby achieving a transmission connection between the two. In this embodiment, the planet carrier 446 is in a Z shape. One end of the planet carrier 446 is connected with a sleeve and the other end is connected with a rotating shaft. The extension directions of the sleeve and the rotating shaft are parallel. The sleeve is sleeved on the output shaft of the first driving motor 42, and the inner diameter of the sleeve is larger than the outer diameter of the output shaft; the planet gear 445 is rotatably connected with the rotating shaft at the end of the planet carrier 446 through a bearing.

[0056] In this embodiment, the first partition plate 442 is installed on the side close to the body of the first driving motor 42, and the second partition plate 447 is installed on the side close to the swing arm 43. At the same time, in this embodiment, the second partition plate 11 and the swing arm 43 are fixedly connected through the second connecting rod 449. Specifically, one end of the second connecting rod 449 is fixedly connected with the outer edge of the second partition plate 11, and the other end is fixedly connected with the side of the swing arm 43 close to the bottom plate 421.

[0057] Based on the Figure 7 shown planetary gear set 44, when the output shaft of the first driving motor 42 rotates, it will first drive the sun gear 444 to rotate self, and the sun gear 444 will continue to drive the ring gear 443 to rotate self relative to the output shaft of the first driving motor 42 through the planet gear 445. During this process, the combination of the first partition plate 442 and the second partition plate 447 rotates with the ring gear 443, and drives the swing arm 43 to rotate relative to the output shaft through the second connecting rod.

[0058] In this embodiment, the swing arm 43 is used to fix the linear module 45. As Figure 6 shown, the execution module is composed of a second driving motor 453, a lead screw 451 and a slider as a counterweight. Vertical plates 423 perpendicular to the bottom plate 421 are provided at both ends of the bottom plate 421 in the swing arm 43. Both ends of the lead screw are rotatably connected with the vertical plates 423 at both ends of the bottom plate 421 through bearings. When the second driving motor 453 drives the lead screw to rotate, the slider 452 will translate in the extension direction of the lead screw (X-axis direction). When necessary, other components that can be used as counterweights or heavy objects without other functions, such as iron blocks, etc., can be further fixed on the slider; to improve the centroid adjustment effect of the balance adjustment component 4.

[0059] In the underwater robot of this embodiment, the first drive motor 42 drives the swing arm 43 to rotate relative to the output shaft to adjust the position of the linear module 45 within the entire pressure hull 1, thereby changing the center-of-mass position of the entire underwater robot. Among them, since the first drive motor 42 can only drive the combination of the linear module 45 and the swing arm 43 to rotate relative to the fixed frame 41 in the YOZ plane. This results in limited directions of the center-of-mass offset of the underwater robot. On this basis, the linear module 45 of this embodiment can further use the second drive motor 453 to drive the slide table to translate along the X-axis direction on the lead screw 451. When the slide table moves, the center of mass can be offset within the XOZ plane, thereby expanding the distribution range of the center-of-mass offset directions. Therefore, by coordinately controlling the first drive motor 42 and the second drive motor 453, the center of mass of the underwater robot can achieve more diverse offsets, and then the thrust directions of the two thrusters 2 of the underwater robot can be adjusted more precisely.

[0060] The basic principle of the underwater robot provided in this embodiment to achieve spatial attitude adjustment can be explained in combination with the schematic diagram as Figure 10 shown in the following schematic diagram:

[0061] The heavy object marked in the figure can be used to represent the counterweight composed of the linear module 45, etc. installed on the swing arm 43. In the initial state, the self-gravity G and buoyancy F of the underwater robot are balanced; and the gravity direction of the entire underwater robot coincides with the center line of the pressure hull 1. At this time, the underwater robot remains floating and the two thrusters 2 remain horizontal.

[0062] When it is necessary to drive the underwater robot to dive, the swing arm 43 can be lifted by the first drive motor 42. At this time, the center-of-mass position of the underwater robot is offset, and the gravity direction no longer coincides with the center line of the pressure hull 1. In this state, the underwater robot will spontaneously roll over, and the rolling direction is opposite to the direction of the center-of-mass offset, and the rolling angle is the same as the center-of-mass offset angle, so that the gravity direction coincides with the center line of the pressure hull 1 again. After completing the above attitude adjustment, the thrust directions of the thrusters 2 of the underwater robot are no longer in the underwater direction, but in an inclined downward state.

[0063] After completing the above attitude adjustment, when the thruster 2 rotates forward, the thrust output by the thruster 2 includes a vertically downward component force. When this component force in the vertical direction is greater than or equal to the resultant force of the buoyancy of the underwater robot (the buoyancy will increase during the process of the underwater robot diving from the floating state to the suspended state) and the gravity, the underwater robot can be driven to dive. In addition, considering that the above spatial attitude adjustment usually cannot directly adjust the thruster 2 to the vertical state, but only adjust it to an inclined state. The thrust generated by the thruster 2 in the inclined state will also include a component force in the horizontal direction; therefore, in a static and stable water body, this underwater robot can usually only achieve inclined floating or diving, rather than vertical floating or diving. In a further optimized solution of this embodiment, a balance adjustment chamber can be provided in the pressure hull 1, and then the vertical floating or diving can be achieved by increasing or decreasing the ballast water therein.

[0064] In this embodiment, a gyroscope is installed in the underwater robot to detect the spatial attitude of the underwater robot; so that the controller can more accurately control the operating state of the underwater robot according to the detection results of the gyroscope. In practical applications, the gyroscope can be fixedly installed in the pressure hull 1.

[0065] The controller, as the control center of the underwater robot, is electrically connected to the first drive motor 42, the second drive motor 453, and the gyroscope. The controller in this embodiment includes an attitude control unit, a motion control unit, and a balance control table. Among them, the balance control table includes the rotation angle α of the first drive motor 42 i and the pitch angle θ of the thruster 2 in the YOZ plane i between the mapping relationship, and at any pitch angle θ i state, the displacement distance l of the slide along the X-axis direction j and the h yaw angle β of the thruster 2 in the XOZ plane ij between the mapping relationship. In any state, when the angle of the thrust direction of the thruster 2 needs to be adjusted, according to the offset angle between the target state and the current state of the thrust direction, and then the offset angle is decomposed into three components along the X-axis, Y-axis, and Z-axis directions. Among them, the offset component along the Z-axis direction can be adjusted by controlling the differential operation of the two thrusters 2, the offset component along the X-axis direction can be adjusted by controlling the rotation of the swing arm 43 by the first drive motor 42, and the offset component in the Y-axis direction can be adjusted by controlling the translation of the sliding body by the second drive motor 453.

[0066] In this embodiment, the operating states of the first driving motor 42 and the second driving motor 453 are adjusted by the attitude control unit, while the operating states of the two thrusters 2 are adjusted by the motion control unit. Specifically, the attitude control unit is used to determine the real-time attitude of the underwater robot according to the detection results of the gyroscope in the suspended or moving state, and then query the balance control table to generate instructions for coordinating the control of the first driving motor 42 and the second driving motor 453, and further drive the attitude adjustment by adjusting the centroid position of the underwater robot, and finally reach the target attitude. In this embodiment, the attitude adjustment function is used to adjust the thrust direction of the thruster 2 on the one hand, and can also keep the device stable during the navigation of the underwater robot on the other hand.

[0067] The control logic of the motion control unit includes three categories, namely:

[0068] (ⅰ) Drive the two thrusters 2 to rotate synchronously to achieve forward or backward movement.

[0069] Among them, when both thrusters 2 rotate forward, a backward thrust can be generated, thereby driving the spherical underwater robot forward; when both thrusters 2 rotate backward, a forward thrust can be generated, thereby driving the spherical underwater robot backward.

[0070] (ⅱ) When the thrusters 2 are in an inclined state, drive the two thrusters 2 to rotate synchronously to achieve floating or diving.

[0071] In the underwater robot of this embodiment, in the initial state, both thrusters 2 are kept horizontal. At this time, when the thrusters 2 are started, the underwater robot can only be driven to move on the horizontal plane at a specified depth underwater. In order to drive the underwater robot to float or dive, the centroid position of the underwater robot can be adjusted first through the attitude control unit, so that the underwater robot rolls and reaches the specified spatial attitude. In this spatial attitude, the thrust direction of the thrusters 2 just follows the direction of the target trajectory. At this time, driving the two thrusters 2 to rotate synchronously can drive the underwater robot to move obliquely upward or obliquely downward, that is, to realize the floating or diving action of the underwater robot.

[0072] (ⅲ) When the thrusters 2 are in a horizontal state, perform differential control on the two thrusters 2 to achieve turning.

[0073] In the underwater robot of this embodiment, the two thrusters 2 can rotate synchronously or at an overspeed. In the state where the two thrusters 2 rotate differentially, the underwater robot can achieve turning. For example, when the thrust of the left thruster 2 is backward and the thrust of the right thruster 2 is forward, the underwater robot will turn clockwise; when the thrust of the left thruster 2 is forward and the thrust of the right thruster 2 is backward, the underwater robot will turn counterclockwise.

[0074] To enable the underwater robot to perceive the underwater environment, ultrasonic radars, cameras, depth sensors, positioning modules, etc. can also be installed in the underwater robot in this embodiment, and the above functional modules for realizing environmental perception are electrically connected to the controller. Among them, to install the camera, through holes can be opened in the pressure hull 1, and portholes can be installed at the through holes. Then the camera is installed at the position corresponding to the porthole. At this time, the camera can obtain the environmental image on the side corresponding to the forward direction outside the pressure hull 1 through the porthole. The installed ultrasonic radar can be used to detect obstacles around the underwater robot. The positioning module can adopt a positioning module based on the GPS or Beidou navigation system, and the installed positioning module can be used to perform real-time positioning on the underwater robot. Correspondingly, the depth sensor can be used to detect the depth information of the underwater robot. Among them, the controller can use the data collected by the ultrasonic radar and the camera to detect obstacles underwater, and accurately identify its own spatial position through the detection data of the positioning module and the depth sensor.

[0075] In addition, in a further optimized solution of this embodiment, the underwater robot can also be installed with a temperature and humidity sensor, and then the temperature and humidity inside or outside the underwater robot can be detected through the temperature and humidity sensor.

[0076] Based on the spatial position of the underwater robot collected in real time by the positioning module and the depth sensor, in a further optimized solution of this embodiment, a navigation module is also included in the spherical underwater robot. The navigation module provided in this embodiment realizes navigation in an inertial guidance manner. Specifically, the navigation module can generate a planned path according to the real-time position and target position of the underwater robot. The planned path produced in this embodiment contains multiple path nodes, and the target state information of each path node includes the corresponding attitude information and power information. The navigation module is used to obtain the real-time state information of the underwater robot, and then generate the corresponding attitude adjustment amount and power control amount by combining the target state information and the real-time state information corresponding to the current path node; then send it to the controller of the underwater robot. After receiving the corresponding control information, the controller can query the aforementioned balance control table, and generate an attitude control instruction for adjusting the operating states of the first drive motor 42 and the second drive motor 453 through the attitude control unit, and generate a motion control instruction sent to the two thrusters 2 through the motion control unit. Through this strategy, this embodiment can accurately control the spatial attitude and thrust output of the underwater robot during the entire navigation process, so as to enable the underwater robot to sail smoothly along the established planned path underwater.

[0077] In addition, considering the environmental perception ability of the aforementioned underwater robot, the navigation module of this embodiment is further configured to obtain obstacle information collected by ultrasonic radars and cameras, and adjust the planned path in real time according to the obstacle information, thereby realizing obstacle avoidance. The obstacle avoidance strategy of the underwater robot in this embodiment is as Figure 11 shown, and includes the following steps:

[0078] During autonomous cruising, the ultrasonic radar continuously detects whether there are obstacles ahead. If there are obstacles, the horizontal thruster 2 rotates in reverse until the forward speed of the sphere is reduced to 0. After that, the task of turning right by 90 degrees is executed. After completion, it travels straight at a low speed for 5 seconds. After completion, it turns left by 90 degrees and detects whether there are still obstacles. If there are, the above actions are repeated. Otherwise, the current coordinate position is obtained, and in combination with the target coordinate position, the heading angle is recalculated and it continues to travel straight.

[0079] In the actual application process, the core of the controller in the underwater robot of this embodiment can adopt an STM32 chip. The STM32 chip realizes PID control of the first drive motor 42, the second drive motor 453, and the drive motors of the two thrusters 2 through a PID controller. The navigation module can adopt an IMU inertial navigation module. In this architecture, the typical working mode of the underwater robot is as follows:

[0080] After the underwater robot is started, it first performs system initialization, then initializes the IMU inertial navigation module. Then, the stm32 executes the acquisition task of the IMU inertial navigation module at a frequency of 10Hz, and applies the data to PID control. After collecting the attitude information of the underwater spherical robot, it executes a straight swimming control task similar to that of a dolphin at a control frequency of 10Hz. Then, it judges its own attitude information according to the attitude sensor on the IMU inertial navigation module, calculates the real-time roll angle data according to the collected state data, and performs a difference processing with the set roll angle target value to obtain the real-time error value. Then, this value is input into the above-obtained PID controller for operation, and the output control amount is used as the PWM value and assigned to the first drive motor 42, the second drive motor 453, and the two thrusters 2 in the horizontal direction. The thrusters 2 and the balance adjustment component 4 control the operation of the device according to the preset control instructions, thereby realizing dynamic adjustment of the spatial attitude and power output of the underwater robot.

[0081] The spherical underwater robot provided in this embodiment can be equipped with an IMU inertial navigation sensor, an RGBD camera, a temperature and humidity sensor, a pressure sensor, a water quality sensor, an ultrasonic sensor, etc., forming a perfect environmental monitoring and attitude perception system. The control system collects the data of these sensors in real time, analyzes and makes decisions through the STM32F407 control chip to ensure that the robot can efficiently perform detection tasks. Compared with traditional robots that can only perform simple detection, this solution has richer sensing capabilities and provides reliable data support for various underwater operations.

[0082] The underwater robot provided in this embodiment has a simple structure and can achieve flexible and free underwater navigation, so it is suitable for performing various underwater operation tasks. Typically, this device can be applied to hydrological monitoring. On this basis, this embodiment further provides a hydrological monitoring device, which can use the spherical underwater robot with a single set of thrusters 2 as described above as a vehicle; sensors or detection devices related to hydrological monitoring, such as water quality sensors, water sampling devices, water quality analyzers, etc., are also installed in the vehicle of the hydrological detection device.

[0083] The spherical underwater robot designed in this embodiment with only a single thruster can achieve various complex operations with the help of the balance adjustment component 4, which enables the robot to adapt to various underwater environments, such as irregular terrain, complex water currents, narrow spaces, etc. Compared with traditional underwater robots, the robot in this embodiment can complete detection and navigation tasks more flexibly in complex environments, effectively improving the environmental adaptability.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A spherical underwater robot with a single set of thrusters, characterized in that, It includes: A spherical pressure shell, Two thrusters are symmetrically fixedly mounted on both sides of the pressure hull; the connecting direction of the two thrusters is defined as the X-axis direction, and the thrust direction is defined as the Y-axis direction; A balance adjustment component, which is fixedly connected in the inner cavity of the pressure-resistant shell; the balance adjustment component includes a fixed frame, a swing arm, a first drive motor and a linear module; the swing arm is rotatably connected to the fixed frame; the first drive motor is installed on the fixed frame; the linear module is fixed on the swing arm, and the linear module includes a second drive motor, a lead screw and a slide as a counterweight; the first drive motor is used to drive the combination of the linear module and the swing arm to rotate in the YOZ plane relative to the fixed frame; the second drive motor drives the slide to translate along the X-axis direction on the swing arm through the lead screw; A gyroscope, which is fixed in the pressure-resistant shell and is used to detect the spatial attitude of the underwater robot; A power source, which is located in the pressure-resistant shell and is used to supply power to the underwater robot; A controller, which is electrically connected to a first drive motor, a second drive motor and two thrusters. The controller includes an attitude control unit, a motion control unit and a balance control table; the balance control table contains the rotation angle α of the first drive motor i and the pitch angle θ of the thruster in the YOZ plane i between the mapping relationship, and at any pitch angle θ i in the state, the displacement distance l of the slide table along the X-axis direction j and the h yaw angle β of the thruster in the XOZ plane ij between the mapping relationship; the attitude control unit is used to determine the real-time attitude of the underwater robot according to the detection results of the gyroscope in the suspended or moving state, then query the balance control table, generate instructions for coordinating the control of the first drive motor and the lead screw, and then drive the attitude adjustment by adjusting the centroid position of the underwater robot, and finally reach the target attitude; The motion control unit is used to: i. drive the two propellers to operate synchronously to achieve forward or backward movement; ii. drive the two propellers to operate synchronously to achieve floating or diving when the propellers are in a tilted state; iii. differentially control the two propellers to achieve steering when the propellers are in a horizontal state.

2. The spherical underwater robot with a single set of thrusters according to claim 1, characterized in that: The first drive motor is a servo motor or a stepper motor; the first drive motor is connected to the swing arm through a gear set or a coupling.

3. The spherical underwater robot with a single set of thrusters as described in claim 1, characterized in that: The fixing frame includes a long strip top plate and a plurality of supporting plates perpendicular to the top plate and parallel to each other; the first driving motor is hoisted under the top plate and fixed by the supporting plates, and the output shaft of the first driving motor is parallel to the extension direction of the bottom plate of the fixing frame; The swing arm is L-shaped, including a long strip base plate and a cantilever perpendicular to the base plate; a circular hole is provided at the end of the cantilever away from the base plate; the axial direction of the circular hole is parallel to the extension direction of the base plate; the swing arm is sleeved on the end of the output shaft of the first drive motor through the circular hole thereon, and the two are rotatably connected through a bearing.

4. The spherical underwater robot with a single set of thrusters according to claim 3, characterized in that: The output shaft of the first driving motor is connected to the swing arm via a planetary gear set; The planetary gear set includes: a first separator plate, a ring gear, a sun gear, planet gears, a planet carrier, a second separator plate, a first connecting rod, and a second connecting rod; through holes are provided in the centers of the first separator plate and the second separator plate; the two are sleeved on the output shaft of the first driving motor through bearings; the first connecting rod fixedly connects the two on the opposite sides of the first separator plate and the second separator plate; internal teeth are provided on the inner side of the ring gear, and the ring gear is fixed on one side of the first separator plate close to the second separator plate; the ring gear, the first separator plate, and the second separator plate are coaxially arranged; the outer diameter of the sun gear is smaller than the inner diameter of the ring gear; the sun gear is key-connected to the output shaft of the first driving motor and is located in the center of the ring gear; the planet gears are mounted on the output shaft through the planet carrier; the planet gears are externally meshed with the sun gear and internally meshed with the ring gear, so as to realize the transmission connection between the two; one end of the second connecting rod is fixedly connected to the outer edge of the second separator plate, and the other end is fixedly connected to one side of the swing arm close to the bottom plate.

5. The spherical underwater robot with a single set of thrusters as described in claim 3, characterized in that: Mounting holes are provided on the plate surface of the support plate, and the first driving motor is inserted into the mounting holes of two adjacent support plates for fixation; Vertical plates perpendicular to the bottom plate are provided at both ends of the bottom plate in the swing arm, and both ends of the lead screw are rotatably connected to the vertical plates at both ends of the bottom plate through bearings.

6. The spherical underwater robot with a single set of thrusters according to claim 1, characterized in that: The pressure-resistant shell is assembled by two hemispherical shells, and a sealing ring is provided on the contact surface between the two; And / or A circular partition is provided inside the pressure-resistant shell, and the partition divides the inner cavity of the pressure-resistant shell into an upper cavity and a lower cavity; And / or The power supply uses a rechargeable lithium battery, and the power supply is installed in the upper cavity; the balance adjustment assembly is installed in the lower cavity.

7. The spherical underwater robot with a single set of thrusters according to claim 1, characterized in that: Through holes are provided in the pressure-resistant shell, and portholes are provided at the through holes; The underwater robot includes a camera, which is used to obtain the environmental image on the corresponding forward direction side outside the pressure-resistant shell through the porthole; And / or The underwater robot includes an ultrasonic radar, which is used to detect obstacles around the underwater robot; And / or The underwater robot includes a positioning module, which is used to perform real-time positioning on the underwater robot; And / or The underwater robot includes a depth sensor, which is used to detect the depth information of the underwater robot; And / or The underwater robot includes a temperature and humidity sensor, which is used to detect the temperature and humidity inside or outside the underwater robot.

8. The spherical underwater robot with a single set of thrusters according to claim 7, characterized in that: It further includes a navigation module, which is used to generate a planned path according to the real-time position and target position of the underwater robot; the planned path includes multiple path nodes, and the target state information of each path node includes corresponding attitude information and power information; the navigation module is used to obtain the real-time state information of the underwater robot, and then generate corresponding attitude adjustment amounts and power control amounts in combination with the target information of the corresponding path nodes; and then send them to the controller of the underwater robot.

9. The spherical underwater robot with a single set of thrusters as described in claim 8, characterized in that, The navigation module is further used to obtain the obstacle information collected by the ultrasonic radar and the camera, and perform real-time adjustment on the planned path according to the obstacle information.

10. A hydrological monitoring device, characterized in that, It uses a spherical underwater robot with a single set of thrusters as described in any one of claims 1-9 as a vehicle; sensors or detection devices related to hydrological monitoring are also installed in the vehicle of the hydrological detection device.

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