An unmanned surface vehicle resistant to rough sea conditions and a control method thereof

Abstract

The application discloses an unmanned ship resistant to severe sea conditions and a control method thereof. The unmanned ship comprises a main hull and a plurality of floating bodies. The main hull is provided with guide rails on both sides, and the main hull is connected with each floating body through a scissor suspension mechanism. The scissor suspension mechanism comprises first connecting rods and second connecting rods which cross each other. One end of the first connecting rod is connected with a fixed hinge support on the floating body, and the other end of the first connecting rod slides along the guide rail of the main hull. One end of the second connecting rod is connected with the main hull, and the other end of the second connecting rod is connected with a sliding table hinge support. A piston rod of a hydraulic cylinder penetrates through the sliding table hinge support, and the end of the piston rod is coaxially connected with a fixed support on the floating body. The piston rod is sleeved with a first spring and a second spring which are arranged on both sides of the sliding table hinge support. The piston rod is provided with a first limiting ring and a second limiting ring for limiting the activity range of the springs. The application can resist waves from the sway direction, effectively reduce the hull roll, and guarantee the high-speed and stable navigation of the unmanned ship.

Description

Technical Field

[0001] This invention relates to the field of maritime unmanned aerial vehicle (UAV) navigation control technology, specifically to an unmanned surface vessel resistant to severe sea conditions and its control method. Background Technology

[0002] Traditional small and medium-sized unmanned surface vessels (USVs) generally face a key contradiction: in pursuit of high-speed cruising performance, they are usually designed as monohull or catamaran planing vessels, with light hulls, shallow drafts, and relatively high centers of gravity. This makes them highly unstable when encountering high waves, prone to large rolling, pitching, or even capsizing, which seriously affects navigation safety and mission execution capabilities. On the other hand, in order to enhance wave resistance, it is often necessary to increase the hull size, deepen the draft, and lower the center of gravity, but this will significantly increase the drag and sacrifice speed and maneuverability.

[0003] In existing technologies, some designs use passive anti-roll fins or appendages (such as anti-roll tanks) to alleviate rolling to some extent, but their effect is limited in extreme sea states and they usually cannot actively adapt to changes in sea state for structural optimization; others have designs with retractable appendages, but their adjustment range and shock absorption effect are often insufficient, making it difficult to achieve a fundamental performance leap between high-speed cruise mode and harsh sea state survival mode.

[0004] To reduce the swaying of ships caused by wind and waves, in addition to equipping ships with anti-roll devices, structural optimization of the hull design can also increase hull stability to a certain extent. For example, catamarans are more stable than traditional monohulls, and their deck platform area is much larger than that of monohulls of the same displacement. However, because wave-adaptive catamarans have a fixed structure and generally have a smaller platform load, the length and width of the hull must be increased when large loads are required. In this case, a separate catamaran must be built, significantly increasing costs. Therefore, how to design an unmanned surface vessel with strong wave adaptability and the ability to change the ship's center of gravity height has become an urgent technical problem to be solved. Summary of the Invention

[0005] To overcome the defects and shortcomings of existing technologies, this invention provides an unmanned surface vessel (USV) resistant to severe sea conditions and its control method. The USV is connected to its side floats via a spring-hydraulic parallel shock absorption system. In cruise mode, the main hull is lowered to a low position, and the combination of deep draft, low center of gravity, and spring buffering ensures high-speed and stable navigation. In wind and wave resistant mode, the main hull is forcefully raised to escape the wave impact zone, significantly improving the survivability rate in extreme sea conditions. The height of the connecting rods on both sides of the hull is adjusted by hydraulic cylinders to resist waves from the sway direction, effectively reducing the hull's rolling.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides an unmanned surface vessel resistant to harsh sea conditions, comprising: a main hull and multiple floating bodies;

[0008] The main hull is equipped with guide rails on both sides, and the main hull is connected to each floating body through a scissor-type suspension mechanism. The scissor-type suspension mechanism includes a first link and a second link, which intersect each other.

[0009] The float is equipped with a fixed hinge support, a fixed support and a hydraulic cylinder. One end of the first connecting rod is connected to the fixed hinge support, and the other end of the first connecting rod slides along the guide rail of the main hull. One end of the second connecting rod is connected to the main hull, and the other end of the second connecting rod is connected to a sliding hinge support. The hydraulic cylinder is equipped with a piston rod that passes through the sliding hinge support and the end of the piston rod is coaxially connected to the fixed support.

[0010] The piston rod is provided with a first limiting ring and a second limiting ring, which are respectively located on both sides of the slide table hinge support. A first spring and a second spring are sleeved on the piston rod. One side of the first spring contacts the first limiting ring, and the other side of the first spring contacts one side of the slide table hinge support. One side of the second spring contacts the other side of the slide table hinge support, and the other side of the second spring contacts the second limiting ring.

[0011] As a preferred technical solution, the main hull is provided with a movable hinge support, and the guide rails on both sides of the main hull are provided on the movable hinge support. The other end of the first connecting rod is hinged to the movable hinge support through a pin and slides along the guide rail.

[0012] As a preferred technical solution, the slide table hinge support is equipped with a linear bearing, which contacts the piston rod of the hydraulic cylinder, allowing the piston rod to slide along the axial direction.

[0013] As a preferred technical solution, the main hull and the floating body are also equipped with inertial sensors for detecting the roll angle, pitch angle and acceleration of the main hull and the floating body.

[0014] As a preferred technical solution, the main hull is also equipped with a height sensor to detect the height of the main hull relative to the floating body or the water surface.

[0015] As a preferred technical solution, the float is also provided with a tail fin and a propeller, with the tail fin located at the tail of the float and the propeller located behind the tail fin.

[0016] As a preferred technical solution, the floats are respectively disposed on the port and starboard sides of the main hull, and the floats are streamlined banana-shaped.

[0017] The present invention also provides a control method for an unmanned surface vessel resistant to severe sea conditions, comprising the following steps:

[0018] Collect motion attitude data and environmental data of the unmanned surface vessel (USV) and adjust the USV's mode, including cruise mode and wind and wave resistant mode;

[0019] In cruise mode, the piston rods of all hydraulic cylinders are controlled to retract synchronously. The second limit ring of the piston rod pushes the second spring to compress, which in turn pushes the slide hinge support to move, adjusting the scissor suspension mechanism to lower the main hull to a preset low position.

[0020] In the anti-wave mode, the piston rods of all hydraulic cylinders are extended synchronously, the first limit ring of the piston rod pushes the first spring to compress, and then pushes the slide hinge support to move, adjusting the scissor suspension mechanism to raise the main hull to the preset anti-wave height.

[0021] As a preferred technical solution, the mode of the unmanned surface vessel is adjusted based on a preset algorithm, which includes a threshold judgment method, a wave prediction method, and a manual command method.

[0022] As a preferred technical solution, PID control is adopted for each hydraulic cylinder. In the single-side connecting rod height control, the relationship between the piston rod extension height H of the hydraulic cylinder and the sliding distance x of the bottom fulcrum of the connecting rod is as follows:

[0023]

[0024] Where l represents the length of the link;

[0025] The error calculation for the height PID control formula is as follows:

[0026] e(t) = H ref -H actual (x)

[0027] Where e(t) is the altitude error, H ref For the target height, H actual (x) represents the actual height calculated using x;

[0028] PID control is applied to each hydraulic cylinder as follows:

[0029]

[0030] Where u(t) is the PID control output, K p K i K d These are the proportional, integral, and differential gain coefficients, respectively.

[0031] Two hydraulic cylinders are controlled separately to adjust the main ship's center of gravity. A synchronization error compensation term is introduced to ensure that the two hydraulic cylinders move in unison. The synchronization error compensation term is expressed as follows:

[0032] e sync (t) = x1(t) - x2(t)

[0033] Among them, e sync(t) represents the displacement synchronization error of the two hydraulic cylinders, and x1(t) and x2(t) are the piston rod sliding distances of the two hydraulic cylinders, respectively;

[0034] The synchronous compensation control quantity is:

[0035]

[0036] Among them, u sync (t) represents the synchronous compensation control quantity. These are the PI gain coefficients for synchronous control;

[0037] The final control quantity is expressed as:

[0038]

[0039] in, These are the final control quantities of the two hydraulic cylinders, i.e., the outputs after superimposed synchronous compensation.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) Compared with ordinary unmanned surface vessels, the present invention uses a hydraulic-spring interconnection method to achieve shock absorption. Unlike the existing wave-adaptive vessels with a dual-cylinder parallel structure, the hydraulic suspension arrangement connection method of the present invention can effectively solve the force coupling problem of the suspension at the physical level.

[0042] (2) The present invention adopts an active adaptation mechanism of changing the center of gravity, and dynamically adjusts the height and center of gravity of the main hull through hydraulic lifting, which fundamentally solves the irreconcilable contradiction between the stability of high-speed cruising and the survivability in harsh sea conditions of traditional unmanned surface vessels, and significantly improves the adaptability to all sea conditions.

[0043] (3) The two freely pitching hulls of the present invention can effectively buffer the impact and swaying of the sea waves. Since the hulls can sway freely on their own, when the wave impacts on the left and right sides of the main hull are inconsistent, the floats can sway freely on their own, which can effectively offset the impact and promote the stability of the main hull. The main hull and the floats are provided with a scissor suspension mechanism consisting of a first link and a second link. The suspension mechanism further weakens the fluctuations transmitted from the hull to the stable platform.

[0044] (4) This invention achieves dynamic adjustment of the center of gravity through hydraulic lifting and linkage design of the main hull and the floating body. The full retraction of the hydraulic cylinder causes the main hull to sink to a low position, increasing the draft by 40% and lowering the center of gravity to 0.3-0.5 meters below the baseline. Combined with the pre-compressed spring, a passive shock absorption mechanism is formed, which effectively suppresses the impact of high-frequency waves. The initial pressure of the spring is set to more than 500N, and the stiffness coefficient adopts a non-linear gradual design with a range of 2000-5000N / m to ensure adaptability to waves of different frequencies.

[0045] (5) The hydraulic-spring parallel damping of the present invention adopts a frequency division control strategy. The nonlinear stiffness spring is specifically designed to absorb high-frequency vibrations above 2Hz, with a dissipation efficiency of over 85%. The hydraulic system achieves stepless damping adjustment in the range of 500-5000N·s / m through servo valves with a response time of less than 10ms and PID closed-loop control, and actively suppresses low-frequency waves of 0.1-1Hz. The two mechanisms work together to significantly improve the damping effect.

[0046] (6) The present invention is equipped with a height sensor and an inertial sensor, and adopts three decision-making methods: threshold judgment, wave prediction and manual command. By collecting data such as roll angle, pitch angle and heave acceleration in real time, and combining wave height and period information, the intelligent switching of modes is realized. The position error during the switching process is controlled within 2mm to ensure a smooth transition.

[0047] (7) The floats of the present invention adopt a streamlined banana-shaped design and are symmetrically distributed on both sides of the main hull. A crescent-shaped tail fin and a ducted propeller are set at the stern. This layout can reduce sailing resistance and improve heading stability. Under cross wave conditions, the roll moment can be reduced by 30%. The floats on both sides achieve height adjustment through an independently controlled hydraulic system, allowing asymmetric attitude compensation and further enhancing the wave resistance.

[0048] (8) The present invention adopts a combination design of sliding table hinge support and linear bearing, which enables the linkage mechanism to slide freely along the axis of hydraulic cylinder piston rod when transmitting motion, effectively solving the force coupling problem in the traditional structure. Combined with the coaxial design of the fixed support, the bending stress of the piston rod is reduced by 70%, significantly improving reliability and service life. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall structure of the unmanned surface vessel resistant to harsh sea conditions according to the present invention;

[0050] Figure 2 This is a front view of the unmanned surface vessel of the present invention, designed to withstand harsh sea conditions.

[0051] Figure 3 This is a top view of the unmanned surface vessel of the present invention, which is resistant to harsh sea conditions;

[0052] Figure 4 This is a left view of the unmanned surface vessel of the present invention, designed to withstand harsh sea conditions.

[0053] Figure 5 This is a schematic diagram of the operation of the unmanned surface vessel of the present invention, which is resistant to severe sea conditions, when subjected to roll excitation.

[0054] Figure 6 This is a schematic diagram of the low center of gravity state of the unmanned surface vessel of the present invention, which is resistant to severe sea conditions, when subjected to heave excitation.

[0055] Figure 7 This is a schematic diagram of the high center of gravity state of the unmanned surface vessel of the present invention when subjected to heave excitation in harsh sea conditions.

[0056] Among them, 1-main hull, 2-float, 3-fixed hinge support, 4-first connecting rod, 5-fixed support, 6-spring, 7-slide table hinge support, 8-limiting ring, 9-hydraulic cylinder, 10-tail fin, 11-propeller, 12-moving hinge support, 13-second connecting rod. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0058] Example

[0059] like Figures 1-7 As shown, this embodiment provides an unmanned surface vessel resistant to severe sea conditions, which includes: a main hull 1, and multiple floats 2, a fixed hinge support 3, a first connecting rod 4, a fixed support 5, a spring 6, a sliding hinge support 7, a limiting ring 8, a hydraulic cylinder 9, a tail fin 10, a propeller 11, a movable hinge support 12, and a second connecting rod 13.

[0060] The floats 2 are distributed on both sides of the main hull 1. Each float 2 is fixedly installed with a fixed hinge support 3. One end of the first connecting rod 4 is hinged to the fixed hinge support 3 on the float 2 through a pin, and the other end of the first connecting rod 4 is hinged to the movable hinge support 12 on the main hull 1 through a pin. The other end of the first connecting rod 4 can slide along the preset linear guide rail of the movable hinge support 12.

[0061] One end of the second link 13 is connected to the main hull, and the other end of the second link 13 is hinged to the slide hinge support. The two sides of the slide hinge support are in contact with springs. That is, on the front and rear sides along the sliding direction of the slide hinge support 7, springs 6 that provide buffering and restoring force are symmetrically installed. The springs 6 are initially in a compressed state. One end of the spring is in contact with the slide hinge support 7, and the other end is in contact with the limiting ring 8 that is fixed on the piston rod of the hydraulic cylinder 9.

[0062] Hydraulic cylinder 9 is the core actuator for achieving mode switching. The hydraulic cylinder is connected to a hydraulic control system, which includes a hydraulic pump station, servo valves and controllers. It is used to precisely control the extension and retraction of the hydraulic cylinder according to sensor signals, so as to realize the mode switching and attitude stability of the main hull between the cruising low position and the anti-wave high position. The cylinder barrel of the hydraulic cylinder is rigidly fixed to the float 2 by a flange. The end of the piston rod of the hydraulic cylinder is coaxially connected to the fixed support 5 installed on the main hull 1 by a pin, so as to ensure that the extension and retraction axis of the piston rod is coaxial with the lifting direction, which is used to reduce the bending stress of the piston rod. The slide hinge support 7 contacts the piston rod of the hydraulic cylinder through a linear bearing, so that it can slide along the axial direction.

[0063] In this embodiment, inertial sensors are respectively installed in the main hull and the floating body. The main hull is also equipped with a height sensor. The height sensor is used to detect the height of the main hull relative to the floating body or the water surface. The inertial sensor is used to detect the roll angle, pitch angle and acceleration of the main hull and the floating body.

[0064] A stable parallel support and shock absorption system is formed between the main hull 1 and each float 2. The tail fin 10 is fixedly installed at the tail of the float 2 to provide directional stability. The propeller 11 is fixedly installed at the tail fin of the float 2 at an angle downward as the main propulsion unit.

[0065] In this embodiment, two floats are preferably arranged symmetrically on the port and starboard sides of the main hull. The floats are streamlined banana-shaped, employing a banana-shaped design with excellent drag resistance, primarily providing buoyancy and lateral stability. Their slender design significantly increases lateral restoring moment. The stern integrates a counter-rotating propeller and an adjustable tail fin, providing efficient thrust and enhancing maneuverability through coordinated differential steering, enabling the unmanned surface vessel to maneuver flexibly in rough sea conditions. The overall design, through the coordination of wave prediction and an active control system, allows the floats to intelligently adapt to different sea conditions, significantly suppressing hull rolling while maintaining speed, perfectly balancing the conflicting requirements of speed and stability.

[0066] In this embodiment, the tail fin 10 adopts a crescent-shaped swept-back design, which can effectively comb the propeller wake and reduce vortex generation. This not only significantly reduces rotational drag but also improves directional stability. Its fin edge guide structure can effectively avoid the problem of weed entanglement. The propeller adopts a three-bladed design with a large tilt angle. Specifically, it is a ducted propeller, which is fixedly installed at the tail of the float at a certain angle to the horizontal plane in the underwater direction, located behind the tail fin.

[0067] In this embodiment, the limiting ring 8 is fixed to the piston rod of the hydraulic cylinder by a set screw. When the piston rod extends, the limiting ring on one side pushes the spring on the other side to compress, thereby pushing the slide hinge support 7 to move. Then, when the piston rod retracts, the limiting ring on the other side pushes the spring on the other side to compress, thereby pushing the slide hinge support 7 to move.

[0068] In this embodiment, the piston rod surface of the hydraulic cylinder system undergoes special hardening treatment and chrome plating, maintaining excellent wear resistance and corrosion resistance even in salt spray environments. The hydraulic cylinder is flange-connected to the float, and an integrated displacement sensor achieves millimeter-level positioning accuracy. A sealed structure effectively prevents seawater infiltration even under frequent extension and retraction conditions. The hydraulic circuit employs a dual-redundancy design, with automatic switching between primary and backup oil circuits. Combined with an intelligent pressure compensation valve group, it ensures stable operation even under sudden changes in wave impact loads. A corrugated protective cover is added to the outer wall of the cylinder, preventing marine organism attachment and avoiding entanglement with fishing nets. While ensuring stable lifting and lowering of the main hull, it effectively absorbs wave impact energy from all directions. The hydraulic cylinder and spring damping system are arranged in parallel, forming a rigid-flexible coupled composite damping mechanism. This allows for energy-saving operation in passive mode during normal navigation and switching to active damping mode for strong support in harsh sea conditions. A fixed support structure, forged from high-strength alloy steel, is added to the end of the hydraulic cylinder piston rod, forming a three-point support system coaxial with the hydraulic cylinder. The support has a self-lubricating bearing embedded in it, which can provide radial restraint for the piston rod to prevent lateral bending deformation without affecting its axial free expansion and contraction.

[0069] In this embodiment, the linkage mechanism is forged from high-strength titanium alloy. Its unique variable cross-section I-beam structure ensures lightweight design while providing excellent bending and torsional resistance. The two ends of the linkage are connected by self-aligning spherical bearings, which automatically compensate for installation misalignment between the hydraulic cylinder and the float. Special surface nitriding treatment ensures smooth rotation of the bearings even in seawater environments. A weight-reduction hole filled with damping material is located in the middle of the linkage, reducing weight and effectively suppressing vibration transmission; actual measurements show a 30% reduction in impact load transmitted to the main hull. A bellows-type antifouling sleeve covers the moving parts of the linkage, completely isolating them from salt spray corrosion and preventing fishing net entanglement. The unique geometric fit between the linkage and the hydraulic cylinder ensures the system maintains the optimal force transmission angle at any lifting position, converting hydraulic cylinder thrust into precise vertical lift. The entire linkage mechanism, optimized through finite element method design, maintains a safety factor of over 3.5 even under extreme loads. Its modular structure facilitates quick disassembly and maintenance, serving as a reliable force transmission channel connecting the float and the main hull.

[0070] In this embodiment, a helical spring and a hydraulic damper are arranged in parallel to form a buffer mechanism that combines rigidity and flexibility. The sliding table hinge support uses a high-precision linear guide rail, and its surface is coated with Teflon to ensure smooth movement even in salt spray environments. The spring is made of corrosion-resistant alloy material and filled with silicon-based damping rubber, maintaining linear stiffness characteristics while increasing internal resistance, effectively absorbing high-frequency vibration energy. The hinge point between the sliding table hinge support and the connecting rod uses a self-lubricating spherical bearing, which can automatically adapt to multi-angle swing, and a specially designed limit stop prevents overtravel impact. The entire system is pre-stressed to ensure that all components are always in optimal fit. When encountering wave impact, the spring first buffers the instantaneous impact force, while the sliding table hinge support moves smoothly along the guide rail, slowly releasing the remaining energy through the hydraulic system. The anti-mud and sand sealing structure completely encloses the moving parts, preventing the intrusion of marine pollutants, and the modular design allows the spring assembly to be quickly replaced according to load requirements. This system can maintain stable buffering performance even under 3-meter wave height impact, reducing the instantaneous impact load by more than 70%.

[0071] In cruise mode: When sea conditions are good (e.g., wave height < 1 meter) or high-speed navigation is required, the central controller issues a command. The hydraulic control system drives the hydraulic cylinder 9 to retract synchronously, smoothly lowering the main hull 1 to the preset cruise low position (e.g., the height of the main hull 1 is reduced by 0.5m), lowering the center of gravity and maintaining it. Furthermore, by appropriately adjusting the height of the fixed hinge on the float and simultaneously adjusting the height of the main hull, the draft of the main hull 1 can be changed. In this state, the submerged volume of the main hull 1 increases, the center of gravity is significantly lowered, and the initial stability is greatly improved. The relative motion between the main hull 1 and the float 2 (mainly caused by high-frequency breaking waves) is transmitted through the first link 4 and the second link 13, driving the sliding hinge support 7 to slide along the guide rail, compressing the springs 6 on both sides, forming a highly efficient passive spring damping system to absorb impact energy.

[0072] In wave-resistant mode: When sea conditions deteriorate (wave height consistently >2 meters, or roll / pitch angle exceeds the threshold), or when extreme waves are predicted, the controller issues a lifting command. All hydraulic cylinders 9 extend synchronously, overcoming water resistance and spring force, to rapidly lift the main hull 1 to a preset wave-resistant height (e.g., the bottom of the main hull is lifted 1.2 meters above the water surface) and maintain it. In this state: the main hull 1 is significantly lifted off the water surface, effectively avoiding direct wave impact and wetting, and significantly reducing wave load and drag. Wave energy is mainly borne by the lower-positioned and streamlined float 2. The violent movement of the float 2 (large-amplitude low-frequency swaying) drives the sliding hinge support 7 through the connecting rod, compressing / stretching the spring 6 on one hand, and pushing the piston rod of the hydraulic cylinder 9 on the other. During the switching process (lifting or lowering), the controller uses a high-precision position sensor for closed-loop control to ensure that all hydraulic cylinders 9 move strictly synchronously (position error <2mm), preventing the main hull 1 from tilting and jamming. The hydraulic cylinder speed / output is dynamically adjusted based on altitude, attitude, and pressure feedback to ensure smooth and shock-free switching. After the sea conditions improve, hydraulic cylinder 9 is released controllably, and the main hull 1 smoothly returns to the cruising low position.

[0073] This embodiment also provides the control method for the above-mentioned unmanned surface vessel resistant to severe sea conditions, specifically including:

[0074] The unmanned surface vessel (USV) collects real-time motion attitude data (roll angle, pitch angle, heave acceleration) and environmental data (wave height, period). Based on a preset algorithm, it automatically determines whether it should be in cruise mode or wind and wave resistant mode. When a switch is needed, it generates a lift or descent command to achieve mode transition. The preset algorithm includes three decision-making methods: threshold judgment, wave prediction, and manual command, ensuring that the optimal choice can be made under different operating conditions.

[0075] In cruise mode, all hydraulic cylinders retract synchronously, lowering the main hull to a preset low position and providing stability by utilizing its low center of gravity. The relative motion between the main hull and the floating body is transmitted to the spring system through linkages, forming a passive damping mechanism to absorb the impact of high-frequency waves; at the same time, the propulsion system maintains a high-speed cruise state. This mode is particularly suitable for rapid navigation missions in calm sea conditions.

[0076] When switching to the wave-resistant mode, the hydraulic cylinders forcefully extend, lifting the main hull to a high position, significantly removing it from the water surface to reduce wave impact. The floating body, as the primary wave-bearing unit, moves via connecting rods, simultaneously driving springs and hydraulic cylinders to form a parallel damping system. The hydraulic system, by adjusting servo valves to generate a high-damping state, works in conjunction with the springs to convert the energy of low-frequency giant waves into heat dissipation, significantly suppressing the main hull's rolling. At this time, the propulsion system prioritizes maintaining the basic course, ensuring survivability.

[0077] Upon detection of extreme motion, an emergency avoidance procedure is immediately triggered, forcibly raising the main hull and activating the maximum damping mode. The entire mode switching process employs closed-loop control to ensure high-precision synchronization of each hydraulic cylinder, with position errors controlled within 2mm, achieving a smooth transition and enabling real-time attitude fine-tuning. The center of gravity position is optimized by independently controlling the extension and retraction of hydraulic cylinders or adjusting ballast counterweights.

[0078] In this embodiment, the high-damping state of the hydraulic cylinder is achieved through precise adjustment of the hydraulic oil flow and pressure, while synchronous control relies on real-time position feedback and independent servo valve adjustment. A dual threshold standard is set: a standard threshold is used for modal decision-making, while a higher safety threshold is dedicated to responding to sudden emergencies. This hierarchical control strategy ensures both daily operational efficiency and safety under extreme conditions.

[0079] In this embodiment, the linkage mechanism consists of two rigid rods of length l hinged at the midpoint (in a scissor shape), with the two rods at a certain angle θ. The bottom fulcrum can slide horizontally for a distance of x, and the top is a free end that rises vertically as the mechanism extends. H is the height of the main hull.

[0080] The vertical projection height of a single rod is lcosθ, therefore the total height is:

[0081] H = 2l cosθ

[0082] When the bottom fulcrum slides, the projection of the single rod in the horizontal direction is lsinθ, and the total span is:

[0083] x = 2l sinθ

[0084] Using the trigonometric identity sin 2 θ+cos 2 θ = 1

[0085]

[0086] Substitute into the height formula:

[0087]

[0088] The relationship between the elongation height H and the sliding distance x is as follows:

[0089]

[0090] The error calculation for the height PID control formula is as follows:

[0091] e(t) = H ref -H actual (x)

[0092] Where e(t) is the altitude error, H ref For the target height, Hactual (x) represents the actual height calculated using x;

[0093] PID control is applied to each hydraulic cylinder as follows:

[0094]

[0095] Where u(t) is the PID control output, K p K i K d These are the proportional, integral, and differential gain coefficients, respectively.

[0096] Furthermore, based on the above control scheme, single-side linkage height control can be achieved. Controlling two hydraulic cylinders separately can adjust the main ship's center of gravity. Since the control of the hydraulic cylinders on both sides is delayed and asynchronous, synchronization error control is introduced. The control method is as follows:

[0097] Introducing a synchronization error compensation term to ensure consistent movement between the two cylinders:

[0098] e sync (t) = x1(t) - x2(t)

[0099] Among them, e sync (t) represents the displacement synchronization error of the two hydraulic cylinders, and x1(t) and x2(t) are the sliding distances of hydraulic cylinder 1 and hydraulic cylinder 2, respectively;

[0100] Synchronous compensation control quantity:

[0101]

[0102] Among them, u sync (t) represents the synchronous compensation control quantity. These are the PI gain coefficients for synchronous control;

[0103] Final control quantity:

[0104]

[0105] in, These are the final control quantities, i.e., the output after adding synchronous compensation.

[0106] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An unmanned surface vessel resistant to harsh sea conditions, characterized in that, include: The main hull and multiple floating bodies; The main hull is equipped with guide rails on both sides, and the main hull is connected to each floating body through a scissor-type suspension mechanism. The scissor-type suspension mechanism includes a first link and a second link, which intersect each other. The float is equipped with a fixed hinge support, a fixed support and a hydraulic cylinder. One end of the first connecting rod is connected to the fixed hinge support, and the other end of the first connecting rod slides along the guide rail of the main hull. One end of the second connecting rod is connected to the main hull, and the other end of the second connecting rod is connected to a sliding hinge support. The hydraulic cylinder is equipped with a piston rod that passes through the sliding hinge support and the end of the piston rod is coaxially connected to the fixed support. The piston rod is provided with a first limiting ring and a second limiting ring, which are respectively located on both sides of the slide table hinge support. A first spring and a second spring are sleeved on the piston rod. One side of the first spring contacts the first limiting ring, and the other side of the first spring contacts one side of the slide table hinge support. One side of the second spring contacts the other side of the slide table hinge support, and the other side of the second spring contacts the second limiting ring.

2. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The main hull is equipped with a movable hinge support, and the guide rails on both sides of the main hull are mounted on the movable hinge support. The other end of the first connecting rod is hinged to the movable hinge support through a pin and slides along the guide rail.

3. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The slide table hinge support is equipped with a linear bearing, which contacts the piston rod of the hydraulic cylinder, allowing the piston rod to slide along the axial direction.

4. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The main hull and the floating body are also equipped with inertial sensors to detect the roll angle, pitch angle and acceleration of the main hull and the floating body.

5. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The main hull is also equipped with a height sensor to detect the height of the main hull relative to the floating body or the water surface.

6. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The float is also equipped with a tail fin and a propeller. The tail fin is located at the tail of the float, and the propeller is located behind the tail fin.

7. The unmanned surface vessel resistant to harsh sea conditions according to claim 1, characterized in that, The floats are respectively located on the port and starboard sides of the main hull, and the floats are streamlined banana-shaped.

8. The control method for an unmanned surface vessel resistant to severe sea conditions according to any one of claims 1-7, characterized in that, Includes the following steps: Collect motion attitude data and environmental data of the unmanned surface vessel (USV) and adjust the USV's mode, including cruise mode and wind and wave resistant mode; In cruise mode, the piston rods of all hydraulic cylinders are controlled to retract synchronously. The second limit ring of the piston rod pushes the second spring to compress, which in turn pushes the slide hinge support to move, adjusting the scissor suspension mechanism to lower the main hull to a preset low position. In the anti-wave mode, the piston rods of all hydraulic cylinders are extended synchronously, the first limit ring of the piston rod pushes the first spring to compress, and then pushes the slide hinge support to move, adjusting the scissor suspension mechanism to raise the main hull to the preset anti-wave height.

9. The control method for an unmanned surface vessel resistant to severe sea conditions according to claim 8, characterized in that, The unmanned surface vessel's mode is adjusted based on a preset algorithm, which includes a threshold judgment method, a wave prediction method, and a manual command method.

10. The control method for an unmanned surface vessel resistant to severe sea conditions according to claim 8, characterized in that, For each hydraulic cylinder, PID control is applied. In the single-side connecting rod height control, the relationship between the piston rod extension height H and the sliding distance x at the bottom fulcrum of the connecting rod is as follows: Where l represents the length of the link; The error calculation for the height PID control formula is as follows: e(t)=H ref -H actual (x) Where e(t) is the altitude error, H ref For the target height, H actual (x) represents the actual height calculated using x; PID control is applied to each hydraulic cylinder as follows: Where u(t) is the PID control output, K p K i K d These are the proportional, integral, and differential gain coefficients, respectively. Two hydraulic cylinders are controlled separately to adjust the main ship's center of gravity. A synchronization error compensation term is introduced to ensure that the two hydraulic cylinders move in unison. The synchronization error compensation term is expressed as follows: e sync (t) < x1(t) - x2(t) Among them, e sync (t) represents the displacement synchronization error of the two hydraulic cylinders, and x1(t) and x2(t) are the piston rod sliding distances of the two hydraulic cylinders, respectively; The synchronous compensation control quantity is: Among them, u sync (t) represents the synchronous compensation control quantity. These are the PI gain coefficients for synchronous control; The final control quantity is expressed as: in, These are the final control quantities of the two hydraulic cylinders, i.e., the outputs after superimposed synchronous compensation.

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