A two-degree-of-freedom modular attitude autonomous adjustment method for AUVs

Abstract

This invention relates to a two-degree-of-freedom modular attitude autonomous adjustment device for an AUV, comprising a sealed chamber, a stepper motor, a lead screw, a guide rod, a mounting frame, a counterweight, and an electronic control module. The sealed chamber consists of a chamber body and multiple sealing components to protect the internal structure. The mounting frame comprises a detachable rhomboid seat, limit switches, and a circular boss base to ensure component fixation. The stepper motor engages with the rhomboid seat via the lead screw to achieve attitude adjustment, while the guide rod restricts its rotation. The electronic control module connects to a sensor interface, receives control signals, drives the motor to perform linear motion, adjusts the AUV's center of gravity and attitude, and the limit switches limit the movement stroke to adapt to different mission requirements.

Description

Technical Field

[0001] This invention belongs to the field of autonomous underwater vehicles and relates to a two-degree-of-freedom modular attitude autonomous adjustment device for AUVs. Background Technology

[0002] An Autonomous Underwater Vehicle (AUV) is an unmanned robot capable of performing tasks autonomously underwater. It is typically designed to navigate, explore, sample, and collect data autonomously without direct human control. In practical applications, the pitch and roll attitude control of an AUV plays a crucial role in its navigation in water. However, due to the different types of tasks performed by the AUV, corresponding equipment needs to be changed, leading to variations in the AUV's load, center of gravity, and center of buoyancy. This can cause the AUV to fail to meet the attitude requirements for normal navigation, affecting control performance and safety.

[0003] Currently, the primary methods for attitude adjustment of AUVs (Aircraft Vehicles) are propeller control and rudder control. Propeller control adjusts the AUV's attitude by changing the rotational speed and direction of the propellers deployed around it. Another method is rudder and rudder control, which adjusts the angle of the control surfaces to change the AUV's direction and attitude, similar to ship and aircraft control systems. Both methods have advantages and disadvantages. Propeller control offers high flexibility and fast response, but consumes more energy and has higher maintenance costs. Rudder and rudder control offers advantages such as simple structure and low energy consumption, but lacks maneuverability and is less effective at low speeds. Both methods require design and improvement of the AUV's external structure, resulting in overall complexity and making it difficult to ensure structural integrity. Furthermore, the two methods are suitable for different scenarios and cannot be easily unified. Summary of the Invention

[0004] The purpose of this invention is to improve the difficulty of AUV attitude adjustment and to provide a two-degree-of-freedom modular attitude autonomous adjustment device for AUVs.

[0005] The technical problem solved by this invention is:

[0006] 1. The present invention has a compact structure and does not require additional internal space of the AUV. It can be used as an independent cabin of the AUV or as a mounting device of the AUV. The counterweight can be quickly adjusted according to the needs, and the single-dimensional attitude can be autonomously or manually adjusted.

[0007] 2. It can quickly and effectively adjust the attitude of the AUV according to different mission conditions and load conditions, reduce the energy consumption of the AUV and improve the handling performance of the AUV, so as to meet the navigation requirements of the AUV.

[0008] 3. It can meet modular functional requirements, enabling rapid expansion and improvement to meet different needs. It is also easy to maintain; even if the equipment malfunctions and becomes unusable, it can be quickly disassembled and replaced without affecting the normal operation of other devices, thus reducing safety risks.

[0009] The objective of this invention is achieved through the following technical solution: a two-degree-of-freedom modular attitude autonomous adjustment device for an AUV, comprising a sealed chamber, a through-type linear lead screw stepper motor, a lead screw, a guide rod, a fixing frame, a counterweight, an electronic control module, and a stepper motor drive module. Two devices are present, one deployed longitudinally and the other laterally. The sealed chamber, serving as the carrier of the entire device, consists of four parts: a chamber body, a sealing flange, a sealing chamber cover, and sealing rings. There are three sealing rings, one of which is nested in a groove on the mating end face of the sealing flange and the sealing chamber cover, and the other two are nested in the sealing flange. Within the grooves on the cylindrical surface that mates with the cabin body, both the sealing cover and the sealing flange have an equal number of threaded holes. After they are fitted together and the holes are aligned, they are connected and fixed using hexagonal socket head caps. One end of the cabin body is sealed, and the other end is secured by a single unit consisting of the sealing flange, sealing cover, and sealing ring. There are two fixing brackets, each consisting of a rhomboid seat, a limit switch, and a circular boss base, all three parts being detachable and installable. The end face of the circular boss base has rhomboid grooves, rectangular grooves, and circular grooves, used for mounting and fixing the rhomboid seat, limit switch, and guide rod, respectively. The through-type straight... The lead screw stepper motor is threadedly engaged with the lead screw, and both ends of the lead screw are fixed by the diamond-shaped seat, restricting its rotational and translational motion. The guide rod passes through the positioning hole of the through-type linear lead screw stepper motor and is fixed at both ends by the circular groove of the circular boss base, thereby restricting the rotation of the through-type linear lead screw stepper motor. The counterweights are attached to both ends in the axial direction and the four sides in the circumferential direction of the through-type linear lead screw stepper motor, and their quantity can be added or removed according to actual task requirements. The electronic control module integrates STM32F103 series chips, voltage regulator chips, expansion sensor interfaces, and communication interfaces. The power interface, limit switch, and stepper motor drive interface are fixedly connected to one end face of the fixed frame. The power interface is connected to the AUV power supply through a watertight terminal, and the drive interface is connected to the stepper motor drive module to send drive signals to the stepper motor. The expansion sensor interface is used to expand other sensors such as attitude sensors and depth sensors. The communication interface is connected to the motion controller of the AUV through a watertight terminal. After receiving the control signal, the through-type linear screw stepper motor is driven to perform forward and backward linear motion on the screw without touching the limit switch, thereby adjusting the center of gravity and attitude.

[0010] Furthermore, the sealed cover and the chamber body are made of acrylic material, and the surface has undergone corrosion-resistant and hardened surface oxidation treatment. The sealing ring is a fluororubber O-ring with extremely high acid and alkali resistance and corrosion resistance.

[0011] Furthermore, the counterweight is made of high-density material, such as lead or copper; the lead screw is made of material that meets the requirements of high strength, wear resistance, fatigue resistance, and easy processing, such as 40Cr or 45 steel; and the rhomboid seat is made of material that meets the requirements of high strength, pressure resistance, and easy machining, such as gray cast iron or cast steel.

[0012] Furthermore, the counterweights have the same cross-sectional dimensions, and can be either cuboids or irregular shapes depending on actual needs.

[0013] Furthermore, the entire device adopts a modular design, which can increase or decrease the number of devices according to different needs, and is easy to install and maintain.

[0014] Beneficial effects:

[0015] This invention provides a two-degree-of-freedom modular attitude autonomous adjustment device for AUVs. It enables rapid and efficient attitude adjustment when the AUV changes equipment or performs different tasks, reducing energy consumption and improving maneuverability to meet navigation requirements. The number of mating blocks can be increased or decreased according to actual mission needs, and the adjustable attitude angle is relatively large. The entire attitude adjustment device adopts a modular design, resulting in a simple, compact structure and high reliability. The number and distribution of devices can be adjusted according to actual needs, achieving both pitch and roll angle adjustments. It is easy to install and maintain without affecting the normal operation of other devices. This invention allows for both manual attitude adjustment and intelligent closed-loop control of depth and attitude by collecting relevant self-state information from the AUV's onboard depth and attitude sensors, combined with the AUV's control module and the electronic control module of this invention. Attached Figure Description

[0016] Figure 1 This is a block diagram of the attitude adjustment device;

[0017] Figure 2 This is a diagram showing the location of the attitude adjustment device on the underwater vehicle;

[0018] Figure 3 This is a hardware diagram of the electronic control module;

[0019] Figure 4 This is a flowchart of the attitude adjustment device usage;

[0020] Figure 5 This is a flowchart of the operation of the center of gravity adjustment device. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "upper," "middle," "outer," "inner," etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0023] This invention provides a two-degree-of-freedom modular attitude autonomous adjustment device for AUVs, comprising a sealed chamber 1, a through-type linear lead screw stepper motor 4, a lead screw 6, a guide rod 7, a fixing frame 2, a counterweight 5, and an electronic control module 3. The sealed chamber 1 serves as the carrier of the entire device and consists of four parts: a chamber body 14, a sealing flange 12, a sealing chamber cover 11, and sealing rings 13. There are three sealing rings 13, one of which is nested in the groove of the end face where the sealing flange 12 and the sealing chamber cover 11 meet, and the other two are nested in the groove of the cylindrical surface where the sealing flange 12 and the chamber body 14 meet. The sealing chamber cover 11 and the sealing flange 12 both have an equal number of threaded holes. After they are fitted together and the holes are aligned, they are connected and fixed with hexagonal screws. One end of the chamber body 14 is sealed, and the other end is fastened and fixed by the integral structure formed by the sealing flange 12, the sealing chamber cover 11, and the sealing rings 13.

[0024] There are two fixing frames 2, each consisting of three parts: a rhombus-shaped base 22, a limit switch 21, and a circular boss base 23, and these three parts are detachable and installable. The circular boss base 23 has a rhombus-shaped groove, a rectangular groove, and a circular groove on its end face, used to install and fix the rhombus-shaped base 22, the limit switch 21, and the guide rod 7, respectively. The through-type linear lead screw stepper motor 4 is threadedly engaged with the lead screw 6, and both ends of the lead screw 6 are fixed by the rhombus-shaped base 22, restricting its rotational and translational motion. The guide rod 7 passes through the through-type linear lead screw stepper motor... The positioning hole of the machine 4 is fixed at both ends by the circular groove of the circular boss base 23 to limit the rotation of the through linear screw stepper motor 4. The counterweight 5 is attached to both ends in the axial direction and the four sides in the circumferential direction of the through linear screw stepper motor 4. The number can be added or reduced according to the actual task requirements. The electronic control module 3 is fixed to one end face of the fixed frame 2. After receiving the control signal, it drives the through linear screw stepper motor 4 to perform back and forth linear motion on the screw 6 to adjust the center of gravity and posture.

[0025] Furthermore, the sealed cover 11 and the cabin body 14 are made of acrylic material and the surface is treated with corrosion-resistant and hardened surface oxidation. The sealing ring 13 is made of fluororubber O-ring with extremely high acid and alkali resistance and corrosion resistance.

[0026] Furthermore, the counterweight 5 is made of high-density material, such as lead or copper; the lead screw 6 is made of material that meets the requirements of high strength, wear resistance, fatigue resistance, and easy processing, such as 40Cr or 45 steel; and the rhomboid seat 22 is made of material that meets the requirements of high strength, pressure resistance, and easy machining, such as gray cast iron or cast steel.

[0027] Furthermore, the counterweight 5 has the same cross-sectional dimensions, is a cuboid, and its thickness should not be too thick.

[0028] Furthermore, the entire device adopts a modular design, which can increase or decrease the number of devices according to different needs, and is easy to install and maintain.

[0029] A two-degree-of-freedom modular attitude autonomous adjustment method for AUVs, reference Figure 3 The method includes:

[0030] Step 1: Adjust the buoyancy of the AUV to keep it slightly suspended; after the AUV is launched, if it cannot dive underwater due to estimation error, increase the number of counterweights 5; if it sinks to the bottom due to estimation error, decrease the number of counterweights until the submersible is slightly suspended in the water.

[0031] Step 2: Adjust the pitch state of the AUV; if the pitch angle and depth detected by the attitude sensor and depth sensor of the AUV through the control module and the electronic control device 3 in the center of gravity adjustment device are deviated, a stepper motor movement command can be sent to the device through the communication interface to drive the through linear screw stepper motor 4 to move back and forth along the screw 6 without contacting the limit switch, thereby achieving closed-loop control of depth and attitude; if the AUV with only a tail single-degree-of-freedom motion mechanism needs to float or dive in the suspended state, the through linear screw stepper motor 4 can be controlled to move back and forth along the screw 6 while activating the tail motion mechanism without contacting the limit switch.

[0032] Step 3: Adjust the roll state of the AUV; Deploy the device in the lateral direction. If the AUV detects a deviation between the roll angle and depth feedback from the attitude sensor and depth sensor via the control module and the electronic control device 3 in the center of gravity adjustment device, a stepper motor movement command can be sent to the device through the communication interface to drive the through-type linear screw stepper motor 4 to move along the screw 6 without contacting the limit switch; If the AUV requires high-performance turning maneuvers in forward motion, the through-type linear screw stepper motor 4 can be controlled to move left and right along the screw 6 without contacting the limit switch to change the roll angle, thereby reducing the turning radius of the AUV and improving its passability in complex environments;

[0033] Step 4: After the AUV completes the mission, change the mission payload according to the new mission requirements, and then rebalance and control it using the method described above.

[0034] refer to Figure 2 and Figure 3 The AUV body includes an IMU attitude sensor, a depth sensor, a power supply, and a motion controller. The IMU attitude sensor and depth sensor are connected to the motion controller, which is connected to the power supply. The motion controller is connected to the electronic control device of the center of gravity and attitude adjustment device in this invention through a serial communication interface, transmitting control signals and supplying power. The IMU attitude sensor is used to monitor the pitch and roll angles of the underwater vehicle, and the depth sensor is used to detect the diving depth of the AUV. Both send real-time underwater vehicle status information to the motion controller. The motion controller receives the pitch and depth information from the attitude sensor and depth sensor, and generates corresponding control signals through a corresponding control algorithm. The electronic control device of the AUV's attitude adjustment device receives the control signals generated by the control module and outputs a PWM wave with adjustable pulse frequency and duty cycle to achieve speed and position control of the motor, causing the stepper motor to move linearly along the lead screw, further realizing the attitude adjustment of the underwater vehicle. When one end of the stepper motor touches the limit switch, the microcontroller receives a high-level signal and immediately stops the stepper motor movement to perform mechanical limit.

[0035] Brief description of the control algorithm: The control module in this embodiment includes fuzzy PID (Proportional-Integral-Derivative) control, and the control block diagram is as follows. Figure 4 As shown. First, calculate the difference between the current depth and the desired depth, VD(t) = D. n (t)-D t (t), where D n (t) represents the current depth of the spacecraft, D t VD(t) represents the desired depth, and VD(t) is the difference between the current depth of the vehicle and the desired depth. Next, the desired pitch angle θ is calculated. t =αVD(t), where α is the corresponding proportionality coefficient, and θ t Let θ be the target pitch angle. From this, we obtain the difference between the desired pitch angle and the target pitch angle: VA(t) = θ. t -θ n , where θ n VA(t) represents the current pitch angle, and VA(t) represents the difference between the two.

[0036] At this point, the longitudinal stepper motor is at position X(t), and the control algorithm input is VA(t) along with its integral and derivative, with proportional, integral, and derivative coefficients K respectively. pa K ia K da The parameter adjustment value ΔK is calculated by the following fuzzy algorithm. pa ΔK ia and ΔK da Online adjustment yielded:

[0037] Establish control parameter ΔK pa ΔK ia and ΔK da The fuzzy control rules in Table 1-3 include the error VA(t) and the error change. The range of change is converted into the universe of discourse on the fuzzy set, and its fuzzy subset is determined. The elements in the fuzzy subset are fuzzy linguistic variables.

[0038] Table 1

[0039]

[0040]

[0041] Table 2

[0042]

[0043] Table 3

[0044]

[0045] Wherein: NB, NM, NS, ZO, PS, PM, PB are fuzzy linguistic variables, representing negative large, negative medium, negative small, unchanged, positive small, positive medium, and positive large, respectively. The online adjustment method for the output parameters of the PID controller is characterized in that: in the above fuzzy algorithm, the parameter adjustment value ΔK is based on... pa ΔK ia and ΔK da The control parameter K is adjusted using the following formula. pa K ia K da Online adjustment;

[0046] K = K' + ΔK

[0047] pa pa pa

[0048] K ia =K ia '+ΔK ia

[0049] K da =K da '+ΔK da

[0050] Where: K pa ', K ia ', K da 'ΔK is the preset parameter determined based on the characteristics of the servo system.' pa ΔK ia and ΔK da K is the parameter adjustment value for the output of the fuzzy rule. pa K ia K da These are the final output parameters of the PID controller. The fuzzy PID control equation is:

[0051]

[0052] Similarly, let the difference between the desired roll angle and the target roll angle be... in The current roll angle, The desired roll angle is given by VB(t), and the difference between the two values ​​is given by VB(t). The lateral stepper motor position is Y(t), and the control algorithm input is VB(t) along with its integral and derivative. The proportional, integral, and derivative coefficients are K, respectively. pb K ib K db The parameter adjustment value ΔK is calculated by the following fuzzy algorithm. pb ΔK ib and ΔK db Online adjustment yielded:

[0053] Establish control parameter ΔK pb ΔK ib and ΔK db The fuzzy control rules in Table 4-6 include the error VB(t) and the error change. The range of change is converted into the universe of discourse on the fuzzy set, and its fuzzy subset is determined. The elements in the fuzzy subset are fuzzy linguistic variables.

[0054] Table 4

[0055]

[0056] Table 5

[0057]

[0058]

[0059] Table 6

[0060]

[0061] Wherein: NB, NM, NS, ZO, PS, PM, PB are fuzzy linguistic variables, representing negative large, negative medium, negative small, unchanged, positive small, positive medium, and positive large, respectively. The online adjustment method for the output parameters of the PID controller is characterized in that: in the above fuzzy algorithm, the parameter adjustment value ΔK is based on... pb ΔK ib and ΔK db The control parameter K is adjusted using the following formula. pb K ib K db Online adjustment;

[0062] K pb =K pb '+ΔK pb

[0063] K ib =K ib '+ΔK ib

[0064] K db =K db '+ΔK db

[0065] Where: K pb ', K ib ', K db 'ΔK is the preset parameter determined based on the characteristics of the servo system.' pb ΔK ib and ΔK db K is the parameter adjustment value for the output of the fuzzy rule. pb Kib K db These are the final output parameters of the PID controller. The fuzzy PID control equation is:

[0066]

[0067] The tilt angle is adjusted by controlling the movement of the counterweight based on its position.

[0068] The above description is for reference only. In actual processing, the proportions of various components of the device can be increased or decreased according to actual needs.

[0069] Compared to existing methods that require disassembling the AUV structure and rearranging it to adjust the center of gravity, the purpose of this invention is to design a device that can easily and quickly perform gravity balancing and attitude adjustment on the AUV, saving time. It mainly solves the following problems:

[0070] 1. In view of the fact that the existing technology requires additional propellers or tail rudders and side rudders for AUV attitude adjustment, the AUV attitude adjustment device in this embodiment is equipped as an independent module in the AUV compartment, which will not affect the external structure of the AUV, and can be replaced and adjusted at any time, making it easy to maintain and more convenient.

[0071] 2. In view of the existing technology of adjusting the attitude of a motor-driven heavy object in a certain motion form, the attitude adjustment device for AUV in this embodiment integrates the motor and the heavy object into one unit, which effectively saves the cabin space of the underwater vehicle.

[0072] Compared with similar technologies in the past, this invention can quickly adjust the attitude according to actual needs during the AUV trim process, avoiding frequent disassembly of the underwater vehicle for trim. At the same time, it can be combined with the depth sensor, attitude sensor and other equipment on the AUV to realize the adaptive adjustment of the depth and attitude of the underwater vehicle.

[0073] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A two-degree-of-freedom modular attitude autonomous adjustment method for AUVs, characterized in that, This method is based on a two-degree-of-freedom modular attitude autonomous adjustment device for AUVs. The device includes a sealed chamber, a through-type linear screw stepper motor, a screw, a guide rod, a fixing frame, a counterweight, and an electronic control module. The sealed chamber, as the carrier of the entire device, consists of four parts: the chamber body, a sealing flange, a sealing chamber cover, and sealing rings. There are three sealing rings in total. One of them is nested in the groove of the end face where the sealing flange and the sealing chamber cover meet, and the other two are nested in the groove of the cylindrical surface where the sealing flange and the chamber body meet. The sealing chamber cover and the sealing flange both have an equal number of threaded holes. After they are fitted together and the holes are aligned, they are connected and fixed with hexagonal screws. One end of the chamber body is sealed, and the other end is fastened and fixed by the whole consisting of the sealing flange, the sealing chamber cover, and the sealing rings. There are two mounting brackets, each consisting of three parts: a rhombus-shaped base, a limit switch, and a circular boss base, all of which are detachable and installable. The circular boss base has rhombus-shaped, rectangular, and circular grooves on its end face, used to mount and fix the rhombus-shaped base, the limit switch, and the guide rod, respectively. The through-type linear screw stepper motor is threaded into the screw. Both ends of the screw are fixed by the rhombus-shaped base, restricting its rotational and translational motion. The guide rod passes through the positioning hole of the through-type linear screw stepper motor and is fixed at both ends by the circular grooves of the circular boss base, thus restricting the rotation of the through-type linear screw stepper motor. The counterweights are attached to both ends in the axial direction and the four sides in the circumferential direction of the through-type linear screw stepper motor, and their quantity can be added or removed according to actual task requirements. The electronic control module is fixedly connected to one end face of the mounting bracket. Upon receiving a control signal, it drives the through-type linear screw stepper motor to perform forward and backward linear motion on the screw, adjusting its posture. The method specifically includes: If the AUV cannot achieve the required attitude for navigation due to estimation errors after being launched, the number of counterweights should be increased or decreased. Two of these devices are deployed in the AUV, one vertically and one horizontally, and both devices are on the same horizontal plane; If the pitch angle of the AUV deviates, the through-type linear screw stepper motor in the longitudinally deployed attitude adjustment device moves back and forth along the screw. If the roll angle of the AUV deviates, the through-type linear screw stepper motor in the laterally deployed attitude adjustment device moves back and forth along the screw. After the AUV completes a task and the testing equipment is changed again, rebalance it using the method described above. Based on data collected by onboard attitude sensors, depth sensors, and other devices, the AUV can achieve closed-loop control of depth and attitude through its control module and electronic control device in the center of gravity adjustment system, thus realizing intelligent adjustment.

2. The two-degree-of-freedom modular attitude autonomous adjustment method for AUV according to claim 1, characterized in that, The sealed cover and body are made of acrylic material and the surface has undergone corrosion-resistant and hardened surface oxidation treatment. The sealing ring is a fluororubber O-ring with extremely high acid and alkali resistance and corrosion resistance.

3. The two-degree-of-freedom modular attitude autonomous adjustment method for AUV according to claim 2, characterized in that, The counterweight is made of high-density material; the lead screw is made of material that meets the requirements of high strength, wear resistance, fatigue resistance and easy processing; and the rhomboid seat is made of material that meets the requirements of high strength, pressure resistance and easy machining.

4. The two-degree-of-freedom modular attitude autonomous adjustment method for AUV according to claim 3, characterized in that, The counterweights have the same cross-sectional dimensions, are cuboids, and are not too thick.

5. A two-degree-of-freedom modular attitude autonomous adjustment method for AUVs according to claim 1, characterized in that, The entire device adopts a modular design, which can increase or decrease the number of devices according to different needs, and is easy to install and maintain.

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