Active roll balance system for small underwater vehicle and control method

Abstract

The invention discloses an active roll balance system for a small underwater vehicle and a control method.The active roll balance system comprises a circumferential torque balance module and a cooperative controller, and the circumferential torque balance module comprises a balance weight execution assembly, a gear transmission assembly, a driving motor and a position detection assembly; the balance weight execution assembly comprises a large gear and a balance weight block fixedly installed on one side of the edge of the large gear. An output shaft of the driving motor is connected with the large gear through a gear transmission assembly. The position detection assembly comprises an optical code disc coaxially fixed to the large gear, an infrared counting sensor used for reading the rotating angle information of the optical code disc, and a microswitch used for calibrating the zero position. The cooperative controller is in communication connection with the driving motor, the infrared counting sensor, the microswitch and an attitude sensor in the aircraft. The device has the characteristics of independent torque output, quick response, fine control, compact structure and the like, and can effectively inhibit rolling motion caused by ocean disturbance.

Description

Technical Field

[0001] This invention belongs to the field of underwater vehicle attitude control technology, and in particular relates to an active roll balance system and control method for small underwater vehicles. Background Technology

[0002] Autonomous underwater vehicles (AUVs) play a crucial role in marine exploration, pipeline monitoring, and military reconnaissance. The stability of their navigation attitude, especially their roll stability, is key to ensuring the quality of data acquisition from their onboard acoustic, optical, and other precision sensors. However, due to their small size and low center of gravity, small AUVs are highly susceptible to roll motion caused by turbulence and eddies in complex marine environments, leading to sensor performance degradation, track deviation, and even mission failure. Therefore, developing efficient and reliable roll stabilization technology is a core element in improving the operational efficiency of small AUVs.

[0003] Chinese patent document CN111900899A discloses a roll stabilization system based on dual-rotating motor differential control. This scheme utilizes the speed difference between two coaxially rotating main propulsion motors to generate a torque difference, which serves as the source of anti-roll torque. This method couples the propulsion system with the attitude control system, offering the advantage of eliminating the need for independent actuators and theoretically providing rapid torque response. However, the fundamental flaw of this scheme lies in the irreconcilable functional coupling between attitude control and propulsion control. Specifically, the motor speed difference introduced to achieve roll stabilization inevitably alters the total thrust output of the propeller, causing uncontrolled fluctuations in the vehicle's main propulsion power. This fundamentally contradicts the core control objective of maintaining the AUV's speed and trajectory, which is crucial for roll attitude stabilization. In mission scenarios requiring precise route tracking, constant-speed cruise, or hovering operations, this interference is fatal. Furthermore, the implementation of this scheme relies entirely on a specific counter-rotating propulsion motor structure, resulting in poor universality. Superimposing complex roll control laws onto the main propulsion motors increases the complexity of system control and reliability risks.

[0004] Chinese patent document CN212473863U discloses an independent counterweight roll adjustment device based on worm gear transmission. This scheme uses a motor to drive a worm, which in turn drives a sector worm wheel and its counterweight to swing, generating anti-roll torque. Its advantage lies in constructing an actuator independent of the main propulsion system, fundamentally avoiding coupling with speed and trajectory control, achieving attitude adjustment capability under all operating conditions, and utilizing the self-locking characteristics of the worm gear to reduce steady-state energy consumption. However, while pursuing structural independence, this mechanical solution introduces new inherent performance bottlenecks. First, the worm gear transmission mechanism exhibits significant backlash, leading to decreased control accuracy and difficulty in achieving fine-tuning of the roll angle. Second, the combined inertia of the sector worm wheel and counterweight is enormous, and the worm gear transmission ratio is typically high, resulting in insufficient dynamic response performance of the system, making it difficult to cope with high-frequency disturbances and failing to meet the requirements for real-time, precise, and stable control. More importantly, the device has a complex mechanical structure, with components such as worm gears, sector worm wheels, and support seats occupying a large amount of space. For small AUVs where the cabin space is already extremely limited, its integration applicability and space utilization are not ideal.

[0005] Furthermore, Chinese patent document CN120080974A discloses a scheme for attitude adjustment by moving an internal battery module. This scheme uses an axial drive mechanism such as a lead screw and guide rail to move the battery mass block along the longitudinal axis of the vehicle, changing the center of gravity position, thereby achieving significant attitude adjustments and even switching between operating modes (such as buoyancy and horizontal maneuvering). This type of axial center of gravity adjustment scheme effectively solves the problem of compensating for large-amplitude, static, or gradually changing attitude torques.

[0006] However, this approach, and similar methods involving a single-axis moving mass block, are inherently limited in their attitude adjustment capabilities by the enormous mass inertia of the battery module. This results in a slow dynamic response and a large mechanical time constant, making it unable to quickly and precisely counteract high-frequency, transient roll disturbances (such as turbulence and vortices) in the marine environment. Therefore, it suffers from a significant bottleneck in maintaining high-precision roll stability. Summary of the Invention

[0007] This invention provides an active roll balancing system and control method for small underwater vehicles, which features independent torque output, fast response, precise control, and compact structure. It can effectively suppress roll motion caused by ocean disturbances, ensure the data acquisition quality of acoustic, optical and other mission payloads, and significantly improve the operational efficiency and mission reliability of AUVs in complex hydrological environments.

[0008] An active roll balancing system for a small underwater vehicle includes a circumferential torque balancing module and a cooperative controller. The circumferential torque balancing module is installed inside the sealed compartment of the vehicle and works in coordination with the vehicle's existing axial center of gravity adjustment module through the cooperative controller. The circumferential torque balancing module includes a counterweight execution component, a gear transmission component, a drive motor, and a position detection component; The counterweight actuation component includes a large gear and a counterweight block fixedly installed on one side of the edge of the large gear. The inner ring of the large gear is provided with a bearing structure and fixed with several connecting brackets. The connecting brackets are fixedly connected to the bottom of the axial center of gravity adjustment module. The output shaft of the drive motor is connected to a large gear via a gear transmission assembly. The position detection component includes an optical encoder fixed coaxially with the large gear, an infrared counting sensor for reading the rotation angle information of the optical encoder, and a micro switch for calibrating the zero position. The aforementioned collaborative controller is communicatively connected to the drive motor, infrared counting sensor, micro switch, and attitude sensor in the aircraft.

[0009] Furthermore, the gear transmission assembly is a small gear that meshes with a large gear, with a transmission ratio between 1:5 and 1:8.

[0010] Furthermore, the bearing structure includes a large gear bearing mounted on the inner ring of a large gear, the inner ring of the large gear bearing being mounted on a bearing inner ring fixing ring, and the bearing inner ring fixing ring being fixed to several connecting brackets.

[0011] Furthermore, the end of the inner ring retaining ring of the bearing is axially fixed by a bearing pressure plate, and a shim is provided between the bearing pressure plate and the large gear bearing.

[0012] Furthermore, the drive motor is mounted on the bottom of the bearing pressure plate via a motor mounting bracket.

[0013] Furthermore, the optical code disk is a thin circular disk with at least 36 light-transmitting holes evenly distributed on its circumference.

[0014] Furthermore, the infrared counting sensor and the micro switch are fixedly mounted on one of the connecting brackets via a sensor bracket; The transmitter and receiver of the infrared counting sensor are located on the upper and lower sides of the optical code disk, respectively, and can be accurately aligned with the light-transmitting area of ​​the optical code disk. When the optical code disk rotates with the large gear, the infrared counting sensor will generate a series of pulse signals, and the coordinating controller will calculate the approximate angle of the counterweight rotation by counting the number of pulses. The upper surface of the optical encoder disk is provided with a raised structure. When the raised structure rotates with the optical encoder disk to trigger the micro switch, it indicates that the counterweight is in the mechanical zero position. When the system is powered on and initialized, the drive motor is first controlled to rotate slowly until this zero position signal is found, thereby establishing an absolute angular coordinate system.

[0015] The control method for the aforementioned active roll balancing system includes: The cooperative controller receives roll angle data from the attitude sensor and selects either the axial center of gravity adjustment module or the circumferential torque balance module for dominant adjustment based on the amplitude and frequency characteristics of the roll angle deviation. When the roll angle deviation is greater than the preset amplitude threshold and / or the frequency of deviation change is lower than the preset frequency threshold, it is determined to be a low-frequency large-amplitude disturbance, and the axial center of gravity adjustment module will take the lead in adjustment; when the roll angle deviation is less than the preset amplitude threshold and / or the frequency of deviation change is higher than the preset frequency threshold, it is determined to be a high-frequency small-amplitude disturbance, and the circumferential torque balance module will take the lead in adjustment. When the circumferential torque balancing module performs the main adjustment, the coordinating controller first determines the target angle and direction of the counterweight block to be moved, and then controls the drive motor to drive the counterweight block on the large gear to make circular motion around the longitudinal axis of the aircraft, so that the generated circumferential torque can counteract the roll disturbance.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Achieves high-frequency response and precise control, complementing low-frequency adjustment: Due to the use of a small-mass counterweight and a highly efficient gear transmission mechanism, the moment of inertia of the entire actuator is much lower than that of the moving battery pack scheme, resulting in a small mechanical time constant. This enables the system to respond quickly and cancel out high-frequency, transient roll disturbances (such as turbulence and vortices) in the marine environment, achieving fine and high-precision micro-adjustment of roll attitude and significantly improving control accuracy. This module complements the battery axial adjustment module, together forming a complete attitude control system covering the entire frequency band.

[0017] 2. Resolves the contradiction between effectiveness under all operating conditions and functional coupling: The circumferential torque balancing module provided by this invention is an independently operating actuator whose working principle does not depend on hydrodynamics or the main propulsion system. Therefore, it can work effectively whether in high-speed navigation, low-speed cruising, or hovering operations, completely solving the problem of control surface failure at low speeds, while also avoiding interference from differential propulsion schemes on speed and trajectory.

[0018] 3. Compact structure, high reliability, and easy integration: The circumferential torque balancing module can be installed as an independent, compact unit within the vehicle cabin, occupying little space and making it ideal for space-constrained small AUV platforms. Furthermore, since the high-frequency adjustment task is performed by a small, low-inertia dedicated mechanism, frequent acceleration and deceleration of the bulky battery pack is avoided, thereby reducing wear requirements on the battery drive mechanism and improving the response speed, control accuracy, and long-term reliability of the entire adjustment system.

[0019] 4. Maximizing system efficiency through collaborative control: When working in conjunction with the axial center of gravity adjustment module, the control strategy proposed in this invention can intelligently allocate adjustment tasks. The axial module handles large-amplitude, static deviations, while the circumferential module specializes in high-frequency, dynamic fine-tuning. This master-slave cooperation mode fully leverages the advantages of each module, enabling the entire attitude system to achieve an optimal balance between energy consumption, response speed, and stability, providing crucial assurance for the successful missions of high-payload, long-endurance AUVs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the active roll balancing system in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the circumferential torque balancing module in an embodiment of the present invention.

[0023] Figure 3 This is a cross-sectional view of the circumferential torque balancing module in an embodiment of the present invention.

[0024] Figure 4 This is a control logic diagram of the collaborative controller in an embodiment of the present invention.

[0025] In the diagram: 1-Large gear, 2-Bearing inner ring retaining ring, 3-Drive motor, 4-Motor mounting bracket, 5-Bearing pressure plate, 6-Small gear, 7-Large gear bearing, 8-Micro switch, 9-Sensor bracket, 10-Infrared counting sensor, 11-Connecting bracket, 12-Optical encoder, 13-Counterweight, 14-Shim, 15-Axial center of gravity adjustment module, 16-Circumferential torque balance module. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0028] like Figures 1-3 As shown, an active roll balancing system for a small underwater vehicle is installed inside the sealed compartment of the vehicle and works in conjunction with the vehicle's existing axial center of gravity adjustment module 15. The system includes a circumferential torque balancing module 16 and a cooperating controller.

[0029] The circumferential torque balancing module 16, as a compact unit, is fixedly installed on the bottom of the axially movable center of gravity adjustment module 15 (such as the battery module) inside the aircraft via a connecting bracket 11, and moves together with it. The circumferential torque balancing module 16 mainly includes a counterweight execution component, a gear transmission component, a drive motor (3), and a position detection component.

[0030] The core of the circumferential torque balancing module 16 is a counterweight actuation component that generates restoring torque. This component includes a large gear 1. The large gear 1 is preferably made of 45# steel and has a disc-shaped structure on one side for mounting a counterweight 13. The counterweight 13 is preferably a high-density metal (such as lead) and is fixed to the edge of the disc of the large gear 1 with screws. By driving the large gear 1 to rotate, the counterweight 13 can be driven to move in a circular motion around the longitudinal axis of the aircraft, thereby generating a precisely controllable anti-roll torque.

[0031] The rotational motion of the large gear 1 is provided by a gear transmission assembly and a drive motor 3. In this embodiment, the gear transmission assembly uses a small gear 6, and the drive motor 3 uses a DC motor.

[0032] The pinion 6 is fixed to the output shaft of the drive motor 3 via a key connection or other means. The pinion 6 meshes with the large gear 1, with a transmission ratio between 1:5 and 1:8, forming a single-stage gear reduction and torque-increasing mechanism. When the drive motor 3 receives a control signal, its output shaft drives the pinion 6 to rotate, which in turn drives the large gear 1 and its counterweight 13 to perform angular displacement with a certain precision.

[0033] To ensure smooth and precise rotation of the large gear 1, this invention employs a precision support structure. The large gear 1 is mounted on the outer ring of a large gear bearing 7 via an interference fit or transition fit. The inner ring of the large gear bearing 7 is press-fitted or fixedly mounted on a bearing inner ring retaining ring 2. The bearing inner ring retaining ring 2 is fixedly connected to the bottom of the axial center of gravity adjustment module 15 via a connecting bracket 11. To prevent axial movement of the large gear 1 and the large gear bearing 7, a bearing pressure plate 5 is fixedly connected to the end of the bearing inner ring retaining ring 2 via bolt and nut connectors. Together, they press the inner and outer ring end faces of the large gear bearing 7, and the axial clearance is adjusted by a shim 14 to ensure flexible rotation without wobbling. The bearing pressure plate 5 also serves as the bottom mounting base for the entire support structure.

[0034] The drive motor 3 is fixed as follows: the drive motor 3 is mounted via a motor mounting bracket 4. The motor mounting bracket 4 is fixed to the bottom of the bearing pressure plate 5 with bolts. This layout allows the drive unit, consisting of the drive motor 3 and the pinion 6, to be located on the radial side of the large gear 1. The overall structure is compact and effectively utilizes the space on the side of the large gear 1.

[0035] To achieve closed-loop control, this invention includes a position detection component, comprising an optical encoder 12 and an infrared counting sensor 10. The optical encoder 12 is a thin circular disc, preferably made of a rigid, lightweight material (such as aluminum alloy or engineering plastic). Multiple light-transmitting holes are evenly distributed around its circumference; the number of holes should be no less than 36. A larger number of holes results in higher angle detection accuracy. The optical encoder 12 is coaxially fixed to a large gear 1 with screws and rotates with it. The infrared counting sensor 10 is fixedly mounted on one of the connecting brackets 11 via a sensor bracket 9. Its transmitting and receiving ends are located on the upper and lower sides of the optical encoder 12, respectively, and can be precisely aligned with the light-transmitting hole area of ​​the optical encoder 12. When the optical encoder 12 rotates, the infrared counting sensor 10 generates a series of pulse signals. The coordinating controller can calculate the approximate angle of rotation of the counterweight 13 by counting the number of pulses.

[0036] To calibrate the absolute zero position of the counterweight 13, the system also includes a micro switch 8. The micro switch 8 is fixedly mounted on the same connecting bracket 11 as the infrared counting sensor 10 via a sensor bracket 9. A raised structure is provided on the upper surface of the optical encoder 12. When the raised structure rotates with the optical encoder 12 to trigger the micro switch 8, it indicates that the counterweight 13 is at its mechanical zero position. During system power-on initialization, the drive motor 3 is controlled to rotate slowly until this zero-position signal is found, thereby establishing an absolute angular coordinate system.

[0037] The control method of the active roll balancing system of the present invention, when the circumferential torque balancing module 16 is controlled independently, includes the following steps: The cooperative controller (which may be part of the AUV's main control computer) continuously receives roll angle data from the aircraft's attitude sensors (such as an IMU). When a roll angle deviation from the expected value (typically 0°) is detected, the cooperative controller calculates the target angle and direction for the counterweight 13 to move based on the magnitude and rate of change of the deviation. Subsequently, the controller sends a command (such as a PWM signal) to the drive motor 3, driving it to rotate. The drive motor 3, through the transmission of the pinion 6 and the gear 1, ultimately moves the counterweight 13 to the target position. During this process, the pulse signal fed back by the infrared counting sensor 10 is used to monitor the position in real time, forming a closed-loop control until the roll angle deviation is eliminated.

[0038] When the circumferential torque balancing module 16 and the axial center of gravity adjustment module 15 work together, the collaborative controller will make intelligent decisions based on amplitude-frequency characteristics, and its logic flow is as follows: Figure 4 As shown: An amplitude threshold A0 (e.g., 5°) and a frequency threshold F0 (e.g., 0.5 Hz) are set. For slow, large-amplitude tilts with a roll angle deviation greater than A0 or a frequency lower than F0, the axial center of gravity adjustment module 15 is prioritized for coarse adjustment. For rapid, small-amplitude swaying with a deviation less than A0 or a frequency higher than F0, the circumferential torque balance module 16 of this invention performs fine adjustment. This strategy achieves an optimal balance between system energy consumption and performance.

[0039] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An active roll balancing system for small underwater vehicles, characterized in that, It includes a circumferential torque balancing module (16) and a cooperative controller. The circumferential torque balancing module (16) is installed in the sealed cabin of the aircraft and works in coordination with the existing axial center of gravity adjustment module (15) of the aircraft through the cooperative controller. The circumferential torque balancing module (16) includes a counterweight execution component, a gear transmission component, a drive motor (3), and a position detection component; The counterweight execution component includes a large gear (1) and a counterweight block (13) fixedly installed on one side of the edge of the large gear (1). The inner ring of the large gear (1) is provided with a bearing structure and fixed with several connecting brackets (11). The connecting brackets (11) are fixedly connected to the bottom of the axial center of gravity adjustment module (15). The output shaft of the drive motor (3) is connected to the large gear (1) through a gear transmission assembly; The position detection component includes an optical encoder (12) fixed coaxially with the large gear (1), an infrared counting sensor (10) for reading the rotation angle information of the optical encoder (12), and a micro switch (8) for calibrating the zero position. The collaborative controller is connected to the drive motor (3), infrared counting sensor (10), micro switch (8) and attitude sensor in the aircraft.

2. The active roll balancing system for small underwater vehicles according to claim 1, characterized in that, The gear transmission assembly is a small gear (6) that meshes with a large gear (1), with a transmission ratio between 1:5 and 1:

8.

3. The active roll balancing system for small underwater vehicles according to claim 1, characterized in that, The bearing structure includes a large gear bearing (7) installed on the inner ring of a large gear. The inner ring of the large gear bearing (7) is installed on a bearing inner ring fixing ring (2), and the bearing inner ring fixing ring (2) is fixed to several connecting brackets (11).

4. The active roll balancing system for small underwater vehicles according to claim 3, characterized in that, The end of the bearing inner ring fixing ring (2) is axially fixed by a bearing pressure plate (5), and a gasket (14) is provided between the bearing pressure plate (5) and the large gear bearing (7).

5. The active roll balancing system for small underwater vehicles according to claim 4, characterized in that, The drive motor (3) is mounted on the bottom of the bearing plate (5) via a motor mounting bracket (4).

6. The active roll balancing system for small underwater vehicles according to claim 1, characterized in that, The optical code disk (12) is a thin circular disk with at least 36 light-transmitting holes evenly distributed on its circumference.

7. The active roll balancing system for small underwater vehicles according to claim 6, characterized in that, The infrared counting sensor (10) and the micro switch (8) are fixedly mounted on one of the connecting brackets (11) via the sensor bracket (9); The transmitter and receiver of the infrared counting sensor (10) are located on the upper and lower sides of the optical code disk (12) respectively, and can be accurately aligned with the light-transmitting hole area of ​​the optical code disk (12); when the optical code disk (12) rotates with the large gear (1), the infrared counting sensor (10) will generate a series of pulse signals, and the coordinating controller will calculate the approximate angle of rotation of the counterweight (13) by counting the number of pulses. The upper surface of the optical code disk (12) is provided with a raised structure. When the raised structure rotates with the optical code disk (12) to trigger the micro switch (8), it indicates that the counterweight block (13) is in the mechanical zero position. When the system is powered on and initialized, the drive motor (3) is controlled to rotate slowly until the zero position signal is found, thereby establishing an absolute angular coordinate system.

8. The control method for the active roll balancing system according to any one of claims 1 to 7, characterized in that, include: The coordinating controller receives roll angle data from the attitude sensor and selects either the axial center of gravity adjustment module (15) or the circumferential torque balance module (16) for dominant adjustment based on the amplitude and frequency characteristics of the roll angle deviation. When the roll angle deviation is greater than the preset amplitude threshold and / or the frequency of deviation change is lower than the preset frequency threshold, it is determined to be a low-frequency large-amplitude disturbance, and the axial center of gravity adjustment module (15) performs the main adjustment; when the roll angle deviation is less than the preset amplitude threshold and / or the frequency of deviation change is higher than the preset frequency threshold, it is determined to be a high-frequency small-amplitude disturbance, and the circumferential torque balance module (16) performs the main adjustment. When the circumferential torque balance module (16) performs the main adjustment, the coordinating controller first determines the target angle and direction of the counterweight (13) to move, thereby controlling the drive motor (3) to drive the counterweight (13) on the large gear (1) to make circular motion around the longitudinal axis of the aircraft, so that the generated circumferential torque can counteract the roll disturbance.

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