Center of gravity adjustment device for underwater robot

Abstract

The application discloses a gravity center adjusting device for an underwater robot and belongs to the technical field of underwater robots. The device comprises at least one adjusting unit, the adjusting unit comprises a rotating shaft rotatably installed on a robot frame, and a counterweight and a buoyant material fixed on the two sides of the rotating shaft respectively and distributed on the two sides about the axis; the combination of the counterweight and the buoyant material keeps the total volume unchanged during one rotation of the rotating shaft. The application changes the gravity center position by rotation, and the buoyancy and the buoyant center keep unchanged during the adjustment, thereby realizing single-variable control. The application has the advantages of compact structure, small number of parts, avoidance of problems of large space occupation, easy jamming and complicated control of traditional linear moving type gravity center adjusting devices, high control precision, fast response speed, good reliability and the like, and can be installed on the underwater robot longitudinally or transversely and used for adjusting the pitch or roll attitude respectively.

Description

Technical Field

[0001] This invention belongs to the field of underwater robot technology, and specifically relates to a center of gravity adjustment device for underwater robots. Background Technology

[0002] Underwater robots are playing an increasingly important role in marine resource exploration, underwater engineering operations, and military defense. Their motion performance, stability, and maneuverability during underwater navigation and operations largely depend on the relative relationship between their center of gravity and center of buoyancy. Precise and rapid center of gravity adjustment technology is key to achieving high-precision attitude control and improving the environmental adaptability of underwater robots.

[0003] In existing technologies, most underwater robot center of gravity adjustment schemes follow the traditional principle of "moving a heavy object." For example, Chinese patent CN201910876664.7 discloses a "center of gravity adjustment system for underwater robots," which uses a linear guide mechanism to drive one or more counterweights (such as battery packs) to move along the robot's axial or circumferential direction, thereby changing the overall center of gravity position of the robot. However, such existing schemes based on linear movement have the following significant shortcomings in practical applications: 1. Complex structure and large space occupation: To achieve linear movement of the counterweight, linear guides, lead screws, multiple motors, and complex transmission mechanisms are required. This makes the entire center of gravity adjustment module bulky, occupying valuable internal space of the underwater robot, which is particularly detrimental to the design of miniaturized and compact underwater robots.

[0004] 2. Risk of jamming and swaying: In harsh environments such as deep-sea high pressure, silt, and corrosion, the precision linear guides and lead screw pairs are prone to jamming due to impurities or lubrication failure. Simultaneously, the gap between the moving counterweight and the guide rail can also cause unnecessary swaying during robot movement, affecting control accuracy and stability.

[0005] 3. Complex control model and slow response: Moving the heavy object not only changes the underwater robot's center of gravity, but also, as an independent sealed module, the movement of its drainage volume simultaneously changes the robot's center of buoyancy. This dual-variable coupling change between the center of gravity and the center of buoyancy greatly increases the complexity of the attitude control algorithm, resulting in a slow system response and making it difficult to achieve fast and accurate dynamic attitude adjustments.

[0006] 4. Low integration and limited reliability: In existing solutions, components such as motors, transmission mechanisms, guide rails, and counterweights are scattered, resulting in low integration and complex electrical and mechanical interfaces. This poses challenges to the overall system's reliability and waterproof sealing.

[0007] Therefore, there is an urgent need for a new type of center of gravity adjustment device with a more compact structure, more precise control, faster response, and higher reliability to overcome the shortcomings of existing technologies. Summary of the Invention

[0008] The technical problem solved by this invention is to provide a center of gravity adjustment device for underwater robots, which solves the problems of complex structure, large space occupation, many control variables, and easy jamming in existing underwater robot center of gravity adjustment devices.

[0009] The technical solution adopted in this invention is as follows: A center of gravity adjustment device for an underwater robot, comprising at least one adjustment unit, the adjustment unit comprising: a rotating shaft rotatably mounted on the frame of the underwater robot; a counterweight and a buoyancy material respectively fixed on the radial sides of the rotating shaft, wherein the total volume of the combination of the counterweight and the buoyancy material remains unchanged during one revolution of the rotating shaft; a drive motor, the output shaft of which is coaxially connected to the rotating shaft of one of the adjustment units; and an upper bearing seat and a lower bearing seat for rotatably mounting the rotating shaft on the frame of the underwater robot via bearings.

[0010] Preferably, there are two adjustment units, which are symmetrically arranged on the longitudinal or transverse axis of the underwater robot. The rotating shafts of the two adjustment units are connected by meshing gears, and the two adjustment units rotate synchronously and in opposite directions under the drive of the drive motor.

[0011] Preferably, the counterweight and buoyancy material are combined to form a cylinder, and the center of mass of the counterweight and the axis of the rotating shaft are radially at a predetermined distance to form a lever arm for adjusting the center of gravity.

[0012] Preferably, the counterweights of the two adjustment units always remain symmetrical under the drive of the drive motor.

[0013] Preferably, the rotation axis of the adjustment unit is arranged along the vertical direction of the underwater robot to adjust the pitch attitude of the underwater robot.

[0014] Preferably, the rotating shaft of the adjustment unit is arranged along the longitudinal direction of the underwater robot to adjust the rolling posture of the underwater robot.

[0015] Preferably, the drive motor is a waterproof motor, which is fixed to the underwater robot frame or bearing seat by a motor bracket.

[0016] The beneficial effects of this invention are: 1. Minimalist Structure and High Integration: This invention employs a rotary adjustment principle, achieving center of gravity adjustment with only a few parts such as a rotating shaft, counterweight, buoyancy material, gears, and a motor. Compared to traditional linear movement structures, it eliminates complex guide rails, lead screws, and other components, significantly simplifying the structure and reducing the number of parts. This conserves internal space for the underwater robot, facilitating miniaturization and lightweight design.

[0017] 2. Precise Control and Rapid Response: The core of this invention lies in changing the "offset" direction of the center of gravity through rotation, while the total volume (displacement) of the combination of the counterweight and buoyancy material remains constant during rotation. This means that the robot's total weight and buoyancy remain unchanged throughout the entire adjustment process, and the position of the center of buoyancy also remains constant. The system only needs to adjust the single variable of "center of gravity," making the control model simple and direct. This avoids the problem of coupled changes in the center of gravity and center of buoyancy in traditional solutions, thereby achieving higher control precision and faster attitude response speed.

[0018] 3. Reliable operation with no risk of jamming: Compared to linear motion, rotary motion eliminates long-stroke sliding contact surfaces and exposed precision guide structures. The core moving components of this invention (shaft and bearings) have excellent sealing and lubrication conditions, making them less susceptible to external mud, sand, and corrosive substances. This fundamentally reduces the risk of jamming and shaking, greatly improving operational reliability in complex underwater environments.

[0019] 4. Synchronous transmission and controllable cost: Using a single motor to synchronously drive two symmetrical adjustment units through gears not only ensures the complete synchronization of the movement of the two counterweights (which is crucial for maintaining the robot's lateral or longitudinal dynamic balance), but also avoids the use of dual motors and complex synchronization control algorithms, reducing manufacturing costs and software complexity.

[0020] 5. Multifunctional integration and strong adaptability: By simply changing the installation direction of the device (vertical or horizontal axis), precise control of the underwater robot's pitch or roll attitude can be achieved. Multiple devices can also be used in combination to provide the robot with comprehensive attitude adjustment capabilities. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the three-dimensional structure of the center of gravity adjustment device.

[0022] Figure 2 This is a first schematic diagram of the cross-sectional shape of the counterweight and buoyancy material in an embodiment of the present invention.

[0023] Figure 3 This is a first schematic diagram of the cross-sectional shape of the counterweight and buoyancy material in an embodiment of the present invention.

[0024] Figure 4This is a first schematic diagram of the cross-sectional shape of the counterweight and buoyancy material in an embodiment of the present invention.

[0025] Reference numerals: 1-Upper bearing housing, 2-Rotating shaft, 3-Gear, 4-Drive motor, 5-Motor bracket, 6-Counterweight, 7-Lower bearing housing, 8-Buoyancy material. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1 This embodiment provides a center of gravity adjustment device for an underwater robot. The device mainly includes an adjustment unit, which consists of an upper bearing seat 1, a lower bearing seat 7, a rotating shaft 2, a counterweight 6, and buoyancy material 8. The upper bearing seat 1 and the lower bearing seat 7 are fixed to the internal frame of the underwater robot. The rotating shaft 2 is rotatably mounted between the upper bearing seat 1 and the lower bearing seat 7 via bearings.

[0028] The counterweight 6 (usually a high-density metal material, such as lead, tungsten alloy, or stainless steel) and the buoyancy material 8 (such as foam plastic or hollow glass microsphere composite material) are fixed on both radial sides of the rotating shaft 2, and are distributed on two opposite sides about the axis of the rotating shaft 2. Figures 2 to 4 As shown, the cross-sectional shape of the counterweight can be semi-circular ( Figure 3 ), a fan-shaped structure with grooves ( Figure 4 The counterweight 6 can be any shape that complements the buoyancy material 8, as long as the volume defined by its outermost contour (i.e., the displacement volume) does not change during the rotation of the two components around the pivot 2. For example, the two components can be combined to form a complete cylinder. Preferably, the center of mass of the counterweight 6 should be as far away from the axis of the pivot 2 as possible to generate a larger center of gravity offset moment during rotation.

[0029] Working principle: When the drive motor 4 drives the rotating shaft 2 to rotate, the counterweight 6 and the buoyancy material 8 will rotate synchronously around the axis of the rotating shaft 2. For example, when the counterweight 6 rotates to the left side of the rotating shaft 2, the center of gravity of the entire device and even the underwater robot it is mounted on will shift to the left; when the rotating shaft 2 rotates 180 degrees and the counterweight 6 moves to the right side, the center of gravity will shift to the right. Throughout the rotation process, since the combined external contour of the counterweight 6 and the buoyancy material 8 remains unchanged, its displacement volume is constant, and the buoyancy and the position of the center of gravity do not change. This achieves precise and rapid adjustment of the center of gravity position while keeping the center of buoyancy constant.

[0030] Example 2 like Figure 1As shown, this embodiment provides a more preferred solution based on Embodiment 1. This embodiment includes two identical adjustment units. These two adjustment units are arranged symmetrically about a plane of symmetry of the underwater robot, such as a longitudinal or transverse vertical plane.

[0031] Two gears 3 with the same module and number of teeth are fixed to the upper ends of the rotating shafts 2 of the two adjustment units, and the two gears 3 mesh with each other. A drive motor 4 is fixed to the upper bearing seat 1 or directly to the robot frame via a motor bracket 5. The output shaft of the drive motor 4 is coaxially connected to the rotating shaft 2 of one of the adjustment units. The drive motor 4 is preferably a waterproof and corrosion-resistant motor, and its housing and output shaft are made of materials resistant to seawater corrosion, and it has a sealing structure that meets the underwater working pressure.

[0032] like Figures 2 to 4 As shown, the counterweights 6 of the two adjustment units in the same group are arranged on the two rotating shafts 2 with the same shape and symmetrical position, and maintain the symmetry of position at all times as the drive motor 4 drives and the gear 3 transmits.

[0033] Working principle: When the drive motor 4 is powered on and rotates, it directly drives the first rotating shaft 2 connected to it to rotate. The gear 3 on this rotating shaft 2 drives the gear 3 on the second rotating shaft 2, which meshes with it, to rotate in the opposite direction. Since the two gears 3 are identical, the two rotating shafts 2 rotate at the same speed but in opposite directions, causing the counterweights 6 on the two adjusting units to rotate synchronously and in opposite directions. All the above structural units are made of waterproof and corrosion-resistant materials and processes, and their strength and rigidity meet the requirements for use.

[0034] Application scenarios: Pitch adjustment: The device is installed with the rotating shaft 2 along the vertical direction (up and down) of the underwater robot, and the two adjustment units are symmetrically distributed about the longitudinal (front and back) axis of the robot. When the motor drives the two counterweights 6 to rotate forward synchronously, the overall center of gravity moves forward, and the robot pitches down; when they rotate backward synchronously, the center of gravity moves backward, and the robot pitches up.

[0035] Adjusting the roll: This device is installed with the rotating shaft 2 along the longitudinal direction (front and back) of the underwater robot, and the two adjustment units are symmetrically distributed vertically about the longitudinal axis of the robot. When the motor drives the two counterweights 6 to rotate synchronously to the same side (e.g., the right side), the overall center of gravity shifts to the right, and the robot rolls to the right; when rotating to the left, it rolls to the left.

[0036] Preferably, the device can be distributed in various positions within the robot, thereby enabling the robot to perform actions such as pitching, yawing, and rolling.

[0037] The above describes specific embodiments of the present invention and the technical principles employed. Any modifications or equivalent transformations based on the technical solutions of the present invention should be included within the protection scope of the present invention.

Claims

1. A center of gravity adjustment device for an underwater robot, characterized in that: The device includes at least one adjustment unit, which comprises: a rotating shaft rotatably mounted on the frame of an underwater robot; a counterweight and a buoyancy material fixed on the radial sides of the rotating shaft, wherein the total volume of the combination of the counterweight and the buoyancy material remains unchanged during one revolution of the rotating shaft; a drive motor whose output shaft is coaxially connected to the rotating shaft of one of the adjustment units; and an upper bearing seat and a lower bearing seat for rotatably mounting the rotating shaft on the frame of the underwater robot via bearings.

2. The center of gravity adjustment device for an underwater robot according to claim 1, characterized in that: There are two adjustment units, which are symmetrically arranged on the longitudinal or transverse axis of the underwater robot. The rotating shafts of the two adjustment units are connected by meshing gears. Driven by the drive motor, the two adjustment units rotate synchronously and in opposite directions.

3. The center of gravity adjustment device for an underwater robot according to claim 2, characterized in that: The counterweight and buoyancy material are combined to form a cylinder. The center of mass of the counterweight and the axis of the rotating shaft are at a preset distance in the radial direction to form a lever arm for adjusting the center of gravity.

4. The center of gravity adjustment device for an underwater robot according to claim 2, characterized in that: The counterweights of the two adjustment units always maintain symmetrical positions under the drive of the drive motor.

5. The center of gravity adjustment device for an underwater robot according to claim 2, characterized in that: The adjustment unit's rotating shaft is arranged along the vertical direction of the underwater robot and is used to adjust the underwater robot's pitch attitude.

6. The center of gravity adjustment device for an underwater robot according to claim 2, characterized in that: The adjustment unit's rotating shaft is arranged along the longitudinal direction of the underwater robot and is used to adjust the underwater robot's rolling posture.

7. The center of gravity adjustment device for an underwater robot according to claim 1, characterized in that: The drive motor is a waterproof motor, which is fixed to the underwater robot frame or bearing seat by a motor bracket.

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