An underwater rescue bionic snake-shaped robot and a control method thereof

Abstract

The application provides an underwater rescue bionic snake-shaped robot and a control method thereof. A robot main body is formed by a plurality of joint driving modules connected in series. The joint driving modules are connected through rotary joints to realize multi-degree-of-freedom bending. The robot main body is externally provided with a flexible waterproof layer. An inflatable air bag is arranged on the outer side of the robot main body along the length direction of the robot main body. The air bag is fixed on the outer side of the waterproof layer and is communicated with a gas pump assembly through a flexible gas pipe. The front end of the robot main body is provided with a head propeller, and the rear end of the robot main body is provided with a tail propeller. The control system is used for sending control instructions to the drivers of the joint driving modules and the head propeller and the tail propeller. The application improves the rescue efficiency, has high reliability and good safety.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, and in particular relates to an underwater rescue biomimetic snake robot and its control method. Background Technology

[0002] Existing underwater rescue robots can be mainly divided into two categories. The first category is snake-like robots that use pure biomimetic oscillating propulsion. This type of technology completely imitates the movement of snakes or eels in nature. Its core structure consists of a series of rigid modules connected by active joints, forming a flexible long chain structure with multiple degrees of freedom. A central controller sends periodic oscillation commands with specific phase differences to each joint, causing the robot's body to generate continuous S-shaped waves in the water. These waves interact with the water to generate forward propulsion.

[0003] The drawbacks of this technology include low propulsion efficiency, limited movement patterns and complex control, and poor attitude stability in complex environments. In underwater environments, snake-like robots rely solely on the limited thrust generated by body swaying, especially when needing to overcome water resistance for rapid maneuvers or hovering operations, where power is significantly insufficient. Achieving effective propulsion requires extremely precise coordinated control of the swaying sequence, amplitude, and frequency of multiple joints, resulting in complex algorithms that are easily affected by water flow disturbances. This makes it difficult to achieve rapid and precise non-periodic maneuvers such as turning and backwards, causing the trajectory to deviate from the predetermined path.

[0004] The second type is the snake-like robot with a single propeller at the tail for auxiliary propulsion. This design adds a single propeller thruster to the tail of the purely biomimetic snake-like robot. Its structure can be viewed as integrating a propeller module driven by an independent motor at the end of the aforementioned multi-jointed snake-like body. The working principle is that the propeller acts as the main thruster, providing the primary forward thrust required for cruising, while the multi-jointed body mainly undertakes auxiliary functions such as attitude adjustment, direction control, and adaptation to environmental changes.

[0005] While such technologies solve some of the underwater propulsion problems, maneuverability remains limited, and the range of motion postures is insufficient. Because the primary thrust source is located at the robot's extremities, the turning radius is large, making it difficult to achieve small-range stationary turns or agile U-turns. Overall movement heavily relies on tail thrust, with body joints primarily used for fine-tuning. This limits the full utilization of multi-joint structures to achieve more complex spatial configurations, thus restricting maneuverability. When significant body swaying is needed to assist steering, it may counteract the thrust of the tail propeller, causing internal energy loss and reducing overall energy efficiency.

[0006] Whether purely biomimetic oscillating or tail-mounted single-propeller assisted, existing underwater snake-like robots primarily focus on observation, inspection, or general mobility. Their structural forms and functional designs do not fully consider the needs of proactive and safe underwater personnel rescue. Firstly, they lack proactive mechanisms for stabilizing and surrounding trapped individuals. Existing snake-like robots are mostly long and streamlined, lacking the ability to quickly change their shape to proactively adapt to and surround irregular human contours. When approaching a drowning person, they cannot adjust their joint posture to form a stable U-shaped or ring-like structure to gently surround the person and provide initial restraint and protection.

[0007] Secondly, there is a lack of integrated emergency buoyancy supply devices. Existing technologies typically do not integrate dedicated buoyancy modules that can be activated quickly. Simply dragging or pushing a drowning person during a rescue is often insufficient, especially when the drowning person is unconscious or exhausted. Quickly providing additional positive buoyancy is crucial. However, existing underwater snake robots do not have buoyancy devices such as airbags that can be released or deployed with a single button at critical moments, and cannot effectively assist trapped persons in rising to the surface and stabilizing on the water.

[0008] In summary, existing underwater biomimetic snake-like robots suffer from a fundamental performance imbalance, struggling to balance propulsion capability and maneuverability. Furthermore, in terms of functional expansion, particularly in high-value applications like active underwater rescue, they exhibit systemic deficiencies such as poor morphological adaptability, lack of active stabilization and buoyancy support, and insufficient human-machine collaborative intelligence. These shortcomings limit their application potential in critical areas like life rescue and underwater collaboration. Summary of the Invention

[0009] In view of this, the present invention aims to overcome the shortcomings of the above-mentioned problems in the prior art and proposes an underwater rescue biomimetic snake robot and its control method.

[0010] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0011] In a first aspect, the present invention provides an underwater rescue biomimetic snake-like robot. The robot body is formed by several joint drive modules connected in series. The joint drive modules achieve multi-degree-of-freedom bending through rotational joints. The robot body is provided with a flexible waterproof layer on the outside. An inflatable airbag is provided on the outside of the robot body along its length. The airbag is fixed to the outside of the waterproof layer and connected to an air pump assembly through a flexible air supply pipe. A head propeller is provided at the front end of the robot body and a tail propeller is provided at the rear end of the robot body. The invention also includes a control system, which is used to send control commands to the drivers of each joint drive module and the thrusters of the head propeller and tail propeller.

[0012] Furthermore, the joint drive module includes a joint motor and a cylindrical connector. The cylindrical connector is a machined integral part with a hollow cavity inside to accommodate the motor. Threaded interfaces are machined at both ends of the connector for coaxial docking between modules and for the fixed installation of the motor, thereby achieving rotational drive.

[0013] Furthermore, each joint drive module is divided into a pitch module and a yaw module. The pitch module is used to realize vertical undulating motion, and the yaw module is used to realize horizontal lateral meandering motion. The pitch module and yaw module are arranged alternately in series to form a motion unit.

[0014] Furthermore, the gas delivery pipe is arranged parallel to the serpentine body and is tightly attached to the outer shell by a snap fastener.

[0015] Furthermore, the waterproof layer is made of pressure-resistant flexible rubber TPU material.

[0016] Furthermore, the air pump assembly is fixed on the rigid housing of the propeller thruster, and includes an air pump, an air source tank, and a pull-wire trigger structure. One end of the pull wire is connected to the air pump mechanical trigger, and the other end is fixed to the waterproof layer on the outside of the robot body.

[0017] Furthermore, the air supply pipe is a flexible silicone hose, which is fixed to the surface of the robot's main body shell by a snap-fit ​​method.

[0018] Furthermore, the control system employs a PID controller.

[0019] Furthermore, the PID controller calculates the target bending angle of each joint module based on the geometric parameters of the target shape, and sends it as a position command to the actuators of each joint. All joints move in coordination, causing the robot body to fit the expected continuous curve, as shown below:

[0020]

[0021] Where K is curvature, representing the degree of curvature of the arc. R is the radius of the arc, and L is the joint length. It is the angle of the i-th joint relative to the starting joint.

[0022] Secondly, the present invention provides a control method for an underwater rescue biomimetic snake-like robot, comprising the following steps:

[0023] Driven by a propeller, the robot quickly approaches the drowning person on the water's surface, using the flexibility of its serpentine body and the forward and reverse rotation of the propeller to make fine adjustments to its direction.

[0024] When the distance is close, the control system uses RS485 serial communication to connect to the servo motors of each unit module. The control system processes motion requests and sends specific control commands to each joint controller via UART bus, thereby driving each joint module to bend synchronously, so that the snake-shaped body bends from a straight line into a U-shaped structure, surrounding the drowning person inside.

[0025] The snake-shaped main body bends, and the cable device is gradually tightened. When the preset tension is reached, the air pump is triggered, and the air pump begins to deliver air to the airbag.

[0026] After being inflated, the airbag rapidly expands along the outer side of the snake-shaped body and eventually forms a ring-shaped float structure, which together with the U-shaped curve of the snake body forms a stable enclosure that automatically lifts the drowning person up.

[0027] The robot continued to surround the person in the water, using its propellers to pull the person to a safe area.

[0028] Compared with existing technologies, the underwater rescue biomimetic snake robot and its control method described in this invention have the following advantages:

[0029] This invention adopts a symmetrical drive design with dual propellers at the head and tail, which solves the problems of "insufficient thrust" in pure oscillating robots and "large turning radius" in traditional single-propeller robots. Compared with pure oscillating snake robots, the linear propulsion speed is improved, which can quickly respond to rescue needs; the reduced turning radius enables complex maneuvers such as turning on the spot and agile U-turns, taking into account both high-speed cruising and precise control in narrow spaces.

[0030] This invention uses a multi-joint rapid bending mechanism to form a U-shaped wrapping structure, which can actively adapt to the human body contour and gently wrap around the drowning person without squeezing. This solves the problem of existing robots that "can only drag and cannot stabilize," and prevents secondary injury to the drowning person.

[0031] This invention integrates an airbag and a mechanical pull-wire triggering system, enabling rapid inflation in 1-2 seconds to form a ring-shaped lifebuoy structure. The buoyancy precisely covers the critical parts above the chest of the drowning victim, ensuring that the head naturally floats to the surface, prolonging life support time, and significantly improving the survival rate of drowning victims. It fills the gap in existing technology that "lacks an emergency buoyancy module".

[0032] The invention features low manufacturing costs and a design for screw assembly and quick airbag replacement, allowing for immediate equipment reset after rescue, high reusability, and significantly improved utilization of rescue resources.

[0033] This invention features a human-machine collaborative and user-friendly system that eliminates the need for rescuers to wade through water or come into close contact with drowning victims. It effectively avoids the threats posed by turbulent currents, whirlpools, and other environmental factors to rescuers, significantly reducing their safety risks. It is particularly suitable for emergency rescues in extreme weather or dangerous waters, solving the problem of high risks associated with traditional manual rescue. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a schematic diagram of the overall structure of the underwater rescue biomimetic snake robot of the present invention;

[0036] Figure 2 This is a schematic diagram of the U-shaped embracing structure of the underwater rescue biomimetic snake robot of the present invention;

[0037] Figure 3 This is a schematic diagram of the multi-joint drive module structure of the present invention;

[0038] Figure 4 This is a schematic diagram of the control system structure of the present invention.

[0039] Explanation of reference numerals in the attached figures

[0040] 1- Multi-joint drive module; 2- Tail propeller; 3- Head propeller; 4- Flexible waterproof layer; 5- Airbag; 6- Air pump assembly; 7- Flexible air supply pipe. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0042] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Example 1

[0047] like Figure 1 As shown, this invention provides an underwater rescue biomimetic snake-like robot. The snake-like robot adopts a modular serial structure, consisting of several joint drive modules connected sequentially to form a long strip-shaped main body. The drive modules achieve multi-degree-of-freedom bending through rotary joints to simulate the body movements of a real snake. The robot body is covered with a flexible waterproof layer 4 to protect the drive modules, electrical connection lines, and provide a streamlined contact surface with the water. An inflatable airbag 5 is provided along the length of the robot body, fixed to the outside of the flexible waterproof layer 4 and connected to an air pump assembly 6 via a flexible air supply pipe 7. A head propeller 3 is located at the front end of the robot body, and a tail propeller 2 is located at the rear end. The invention also includes a control system for sending control commands to the actuators of each joint drive module, as well as to the head propeller 3 and tail propeller 2. The control system of this invention uses a host computer, which contains a controller.

[0048] As a further embodiment, the main body of the robot of the present invention is a multi-joint drive module 1, which is composed of multiple standardized joint drive modules connected in series, such as... Figure 3 As shown, each module possesses universal interchangeability and high integration, meeting the needs of flexible arrangement while facilitating maintenance and replacement. Each joint drive module consists of a joint motor and a cylindrical connector, with the cylindrical connector being a single machined part containing a hollow cavity to house the motor. Threaded interfaces are machined at both ends of the connector, facilitating coaxial docking between modules and the fixed installation of the motor to achieve rotary drive. To meet the motion requirements of the biomimetic snake-like structure, adjacent modules are functionally divided into pitch and yaw modules. The pitch module enables vertical undulating motion, while the yaw module enables horizontal lateral meandering motion. The two modules are arranged in series alternately to form the basic motion unit of the snake-like structure. The overall structure is compact, easy to assemble, and provides stable transmission, offering a sound mechanical foundation for realizing biomimetic flexible motion.

[0049] As a further embodiment, the joints of this invention utilize servo motors or intelligent motors as power sources, forming a continuous structure through mechanical connectors. This structure enables the robot to move undulatingly in water and perform U-shaped switching movements resembling a snake's body, such as... Figure 2 As shown.

[0050] like Figure 4 As shown, the control system of this invention adopts a three-layer structure, including an instruction layer, a planning layer, and a behavior layer. The instruction layer is responsible for processing high-level instructions, such as movement gait, speed, steering, and other macro instructions, and then sends the control parameters to the planning layer. The planning layer generates the motion trajectory of each joint, and finally, the behavior layer drives the motor through a PID controller.

[0051] The multiple joint drive modules of this invention rotate under the operation command, enabling the serpentine body to surround the target and form a U-shaped structure. The control system calculates the target bending angle of each joint module in advance based on the geometric parameters of the target shape, and sends it as a position command to the driver of each joint, so that all joints move in coordination, and finally the robot body fits the expected continuous curve.

[0052]

[0053] Among them, curvature The degree of curvature of the arc, ,in The radius of the arc, It is the joint length. For the first joint relative to the starting joint Each joint angle.

[0054] As a further embodiment, the snake-like robot of the present invention achieves high-speed linear movement, turning, and other operations by reversing the rotation of the tail propeller and the head propeller.

[0055] The motion commands at the command layer (such as forward and left turn) are calculated into independent speed and direction control commands for the head propeller and tail propeller. The thrust and differential torque generated by the two propellers are combined to form the required overall propulsion force and steering torque of the robot.

[0056] The thrust generated by the head propeller and torque for:

[0057]

[0058] ;

[0059] Similarly, the thrust generated by the tail propeller and torque for:

[0060]

[0061]

[0062] in, , , , These are the head and tail propeller speeds, thrust coefficients, and torque coefficients.

[0063] As a further embodiment, the waterproof layer of the present invention is made of pressure-resistant flexible rubber TPU material, which is closely fitted to the serpentine body and allows it to bend and deform, and the airbag is bonded and fixed to the outside of the waterproof layer.

[0064] As a further embodiment, the airbag of this invention has an elongated structure that extends along the outer side of the snake-like robot's main body. The airbag is made of a lightweight, high-toughness material and provides buoyancy upon inflation. It is connected to an air pump assembly via a flexible air supply tube.

[0065] As a further embodiment, the air pump assembly of the present invention is fixed to the rigid housing of the thruster and includes an air pump, an air source tank, and a pull-wire trigger structure. One end of the pull wire is connected to the air pump's mechanical trigger, and the other end is fixed to the waterproof layer on the outside of the serpentine body. When the serpentine body bends, the pull wire is tightened accordingly, and automatically triggers the air pump to inflate after reaching a set tension. The air pump is connected to the airbag through a flexible air delivery tube, enabling rapid inflation of the airbag.

[0066] As a further embodiment, the air supply tube of the present invention is a flexible silicone hose arranged along the surface of the snake-shaped main body, which can be freely bent as the snake robot moves. The air supply tube is fixed to the surface of the outer shell by a snap-fit ​​method.

[0067] When using this invention, the first step is to install and debug each component. Securely fix the air pump and propeller to their respective positions on the snake-like robot, ensuring the air pump can properly inflate the airbags and the propeller can operate normally for propulsion. Attach the airbags to the outside of the robot's waterproof layer, connecting the air pump and airbags via an air supply pipe to ensure smooth gas delivery. Simultaneously, attach the inflation cable device to the waterproof layer, keeping the cable in a standby, untriggered state.

[0068] The operator manually and smoothly places the prepared robot into the water, and controls the propeller to make the snake-like rescue robot move in a straight line towards the target water area.

[0069] When the robot approaches within approximately 0.5-1.5 meters of the drowning person, it begins its rescue operation. The control system sequentially drives multiple servo motors, causing the snake's body to rapidly bend from a straight line into a U-shaped encirclement. As the two ends of the snake approach each other during the bending process, the fixed rope along the outer edge is tightened.

[0070] The impact pin inside the air pump pierced through quickly. The compressed gas inside the cylinder is instantly introduced into the air bladder through the air supply tube. The air bladder inflates rapidly within approximately 1-2 seconds, quickly expanding from its attached state to form a ring-shaped buoyancy structure on the side of the snake-like robot. This, together with the snake's U-shaped curve, forms a stable enclosure, automatically lifting the drowning person. The inflated air bladder provides uniform buoyancy, effectively raising the drowning person's chest and upper body, ensuring the head naturally floats to the surface. Upon return,

[0071] The snake-like robot maintains a U-shaped, undulating posture, continuously encircling the drowning victim. Its tail propeller provides low-speed thrust towards the shore or rescue boat, aided by the stable buoyancy provided by airbags to achieve the rescue. After the rescue, the used airbags can be quickly removed by opening their maintenance ports. The air cylinder was replaced with a new one, and after deflating it, the airbag was reattached to the side of the snake robot in preparation for the next rescue operation.

[0072] The operator of this invention can more precisely control the robot to approach the drowning victim through manual control, improving rescue efficiency. The entire triggering process is achieved through the snake-like robot's posture transformation movements, ensuring high reliability and a low probability of false triggering, guaranteeing accurate activation of the U-shaped life ring when rescue is needed. The inflated U-shaped buoyancy ring can quickly encircle and support the drowning victim, ensuring the victim's head remains above water, providing crucial life support. Combined with the coordinated action of the propeller and airbag buoyancy, the snake-like robot moves stably with the drowning victim, greatly improving the safety of water rescues.

[0073] Example 2

[0074] A control method for an underwater rescue biomimetic snake-like robot includes the following steps:

[0075] Driven by propellers, the robot quickly approaches the drowning person on the water's surface, using the flexibility of its serpentine body and the forward and reverse rotation of the propellers to make minor directional adjustments.

[0076] When the distance is judged to be close, the host computer controller connects to the servo motors of each unit module via RS485 serial communication. Then, the host computer processes the motion request and sends specific control commands to each joint controller via the UART bus. This controls the system to drive each joint drive module to bend synchronously, so that the snake-shaped body bends from a straight line into a U-shaped structure, enveloping the drowning person inside.

[0077] As the serpentine body bends, the cable device is gradually tightened. When the preset tension is reached, the air pump is triggered, and the air pump begins to supply air to the airbag.

[0078] After being inflated, the airbag rapidly expands along the outer side of the serpentine body, eventually forming a ring-shaped float similar to a lifebuoy. This structure can support a drowning person and prevent them from sinking.

[0079] The robot continued to surround the person in the water, using its propellers to pull the person to a safe area.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic snake-like robot for underwater rescue, characterized in that: The robot body is formed by several joint drive modules connected in series. The joint drive modules achieve multi-degree-of-freedom bending through rotational joints. The robot body is provided with a flexible waterproof layer. An inflatable airbag is provided along the length of the robot body. The airbag is fixed to the outside of the waterproof layer and is connected to an air pump assembly through a flexible air supply pipe. The robot body has a head propeller at the front end and a tail propeller at the rear end. It also includes a control system, which is used to send control commands to the drivers of each joint drive module and the head propeller and tail propeller thrusters.

2. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The joint drive module includes a joint motor and a cylindrical connector. The cylindrical connector is a machined integral part with a hollow cavity inside to accommodate the motor. Threaded interfaces are machined at both ends of the connector for coaxial docking between modules and for the fixed installation of the motor, thereby achieving rotational drive.

3. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The adjacent joint drive modules are divided into pitch modules and yaw modules. The pitch module is used to realize vertical undulating motion, and the yaw module is used to realize horizontal lateral meandering motion. The pitch modules and yaw modules are arranged alternately in series to form a motion unit.

4. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The gas delivery pipe is arranged parallel to the serpentine main body and is tightly attached to the outer shell by a buckle.

5. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The waterproof layer is made of pressure-resistant flexible rubber TPU material.

6. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The air pump assembly is fixed to the rigid housing of the propeller thruster and includes an air pump, an air source tank, and a pull-wire trigger structure. One end of the pull wire is connected to the air pump mechanical trigger, and the other end is fixed to the waterproof layer on the outside of the robot body.

7. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The air supply pipe is made of flexible silicone tubing and is fixed to the surface of the robot's main body shell by a snap-fit ​​method.

8. The underwater rescue biomimetic snake-like robot according to claim 1, characterized in that: The control system uses a PID controller.

9. The underwater rescue biomimetic snake-like robot according to claim 8, characterized in that: The PID controller calculates the target bending angle of each joint module based on the geometric parameters of the target shape, and sends it as a position command to the actuators of each joint. All joints move in coordination, causing the robot body to fit the expected continuous curve, as shown below: ； Where K is curvature, representing the degree of curvature of the arc. R is the radius of the arc, and L is the joint length. It is the angle of the i-th joint relative to the starting joint.

10. A control method for an underwater rescue biomimetic snake-like robot, characterized in that: Includes the following steps: Driven by a propeller, the robot quickly approaches the drowning person on the water's surface, using the flexibility of its serpentine body and the forward and reverse rotation of the propeller to make fine adjustments to its direction. When the distance is close, the control system uses RS485 serial communication to connect to the servo motors of each unit module. The control system processes motion requests and sends specific control commands to each joint controller via UART bus, thereby driving each joint module to bend synchronously, so that the snake-shaped body bends from a straight line into a U-shaped structure, surrounding the drowning person inside. The snake-shaped main body bends, and the cable device is gradually tightened. When the preset tension is reached, the air pump is triggered, and the air pump begins to deliver air to the airbag. After being inflated, the airbag rapidly expands along the outer side of the snake-shaped body and eventually forms a ring-shaped float structure, which together with the U-shaped curve of the snake body forms a stable enclosure that automatically lifts the drowning person up. The robot continued to surround the person in the water, using its thrusters to pull the person to a safe area.

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