Depth control method for underwater anti-flow motion of microminiature AUV (Autonomous Underwater Vehicle)
By calculating the seawater density difference and using depth sensors and PID control algorithms, AUVs are controlled to perform depth fine-tuning and horizontal flow resistance propulsion in underwater flow resistance environments, which solves the problem that existing AUVs are slow in response speed and low accuracy in fixed depth acquisition tasks. The problem of high-precision depth control and stable flow resistance propulsion is achieved.
Patent Information
- Application Number
- CN202411859173.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-02-18
AI Technical Summary
When performing acquisition tasks at fixed depth, the adjustment response speed is slow and the accuracy is low, and the horizontal flow resistance propulsion task cannot be performed, and it is not suitable for some detection tasks with high requirements.
By calculating the seawater density difference, the volume change of AUV is obtained, the oil bag oil volume at the target depth is set, and the depth sensor and PID control algorithm are used to control the pitch motor and thruster to make the AUV fine-tune in a wavy forward posture to achieve the goal After depth, horizontal flow resistance propulsion is carried out.
It realizes deep regulation of AUV in an underwater flow-resistant environment, with fast response speed and high control accuracy, so that AUV can perform horizontal flow-resistant propulsion tasks and achieve stability of long-term localized operations underwater.
Smart Images
Figure CN119460034A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of AUVs, and in particular relates to a depth control method for underwater anti-current motion of a micro AUV. Background Art
[0002] AUV (autonomous underwater vehicle) is an underwater intelligent transport equipment that does not rely on a driver. It has good maneuverability and is mainly used in underwater rescue, submarine pipeline detection, marine resource survey and other operational tasks. It has objective application value and far-reaching research significance. The micro-AUV can maintain the required depth in the water through depth control and is the main equipment for underwater exploration and information collection. Most current AUVs use buoyancy adjustment to control when performing fixed-depth collection tasks, but due to the slow response speed and low accuracy of the adjustment, they cannot perform horizontal anti-current propulsion tasks and are not suitable for some detection tasks with higher requirements.
[0003] In view of the above-mentioned prior art, it is necessary to improve the existing structure. To this end, the applicant has made a useful design, and the technical solution to be introduced below is produced in this context. Summary of the invention
[0004] The purpose of the present invention is to provide a depth control method for underwater anti-current motion of a micro AUV, which has fast response speed and high control accuracy, so that the AUV can perform horizontal anti-current propulsion tasks and achieve stability of long-term localized underwater operations.
[0005] The object of the present invention is achieved by a method for controlling the depth of a micro-AUV underwater anti-current motion, comprising the following steps:
[0006] S1) Calculate and set the oil volume of the oil sac at the target depth according to the AUV volume change obtained by the seawater density difference;
[0007] S2) determining the adjustment method based on the data returned by the depth sensor, and outputting the target pitch value through the PID control algorithm;
[0008] S3) controlling the pitch motor and the thruster to make the AUV advance in a wave-like manner to perform depth fine-tuning, and turning off the thruster after reaching the target depth;
[0009] S4) Control the pitch motor to level the AUV and then perform horizontal anti-current propulsion.
[0010] In a specific embodiment of the present invention, in the step S1), the AUV is balanced according to the seawater density. At this time, the gravity is equal to the buoyancy. Assuming the mass of the AUV is m, the formula for calculating the volume change of the AUV is:
[0011] ΔV= m(r 2 -r 1 )(1)
[0012] ρ 1 ρ 2
[0013] Where: 1 is the seawater density during trimming, ρ 2 The seawater density at the target depth in the mission sea area;
[0014] The formula for calculating the oil volume in the oil sac is obtained from formula (1):
[0015]
[0016] Where: P 0 is the neutral oil volume, V F The total amount of oil in the buoyancy control unit return oil system.
[0017] In another specific embodiment of the present invention, in the step S2), the depth adjustment control is triggered when the deviation value of the target depth |Δd|≥h is determined according to the data fed back by the depth sensor, where h is the depth deviation range, and the formula for calculating the output pitch value is:
[0018]
[0019] Wherein, u(t) represents the output pitch value; Indicates the difference between the system feedback pitch value and the target pitch value; K is a constant; D com represents the target depth; D(t) represents the feedback value of the depth sensor; Indicates the proportional coefficient of pitch PID; K DP Indicates the scaling factor of the depth PID.
[0020] In another specific embodiment of the present invention, in the step S3), according to the positive or negative situation of the output pitch value, the main controller controls the pitch motor to drive the battery pack to move longitudinally, so that the AUV presents a head-up or head-down posture; and during the adjustment process, when the system feedbacks the pitch value With target pitch value At the same time, the main thrusters are turned on to reduce the response time of the entire depth adjustment process. During the process, the AUV adjusts its depth in a wave-like manner.
[0021] In another specific embodiment of the present invention, in step S4), the target pitch value As the system input, the AUV is adjusted to a horizontal state as a whole and the horizontal fixed-depth anti-current propulsion is started.
[0022] Due to the adoption of the above structure, the present invention has the following beneficial effects compared with the prior art: firstly, the final weight and neutral oil volume of the AUV are obtained through initial balancing, and the volume change of the AUV is obtained according to the seawater density difference, so as to calculate the adjustment amount of the buoyancy adjustment unit under the corresponding density, thereby realizing the rough depth control of the AUV at the target depth; secondly, after the AUV judges the deviation value of the target depth, the actual pitch and depth are controlled by the closed-loop control, combined with the PID control algorithm, and the pitch motor and the propeller are controlled to make the AUV fine-tune the actual depth in a wave-like motion. Under this method, the depth control capability of the AUV reaches the meter level; thirdly, during the fine-tuning process of the AUV, when the pitch value fed back by the system has the same sign as the target pitch value, the propulsion motor is turned on to reduce the response time of the depth fine-tuning; fourthly, the control accuracy is high, so that the AUV can perform the horizontal anti-current propulsion task and realize the stability of long-term local operation underwater. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of the process of the present invention;
[0024] Figure 2 It is the control loop diagram of the PID control algorithm of the present invention. DETAILED DESCRIPTION
[0025] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but the description of the embodiments is not a limitation of the technical solution. Any changes in form rather than substance based on the concept of the present invention should be regarded as the protection scope of the present invention.
[0026] In the following description, all concepts related to directionality (or orientation) such as up, down, left, right, front and back are referring to the position state of the figure being described, and are intended to facilitate public understanding. Therefore, they should not be understood as special limitations on the technical solution provided by the present invention.
[0027] See Figure 1 The present invention relates to a depth control method for underwater anti-current motion of a micro-AUV, comprising the following steps:
[0028] S1) calculating and setting the oil volume of the oil sac at the target depth according to the AUV volume change obtained by the seawater density difference;
[0029] S2) determining the adjustment method based on the data returned by the depth sensor, and outputting the target pitch value through the PID control algorithm;
[0030] S3) controlling the pitch motor and the thruster to make the AUV advance in a wave-like manner to perform depth fine-tuning, and turning off the thruster after reaching the target depth;
[0031] S4) Control the pitch motor to level the AUV and then perform horizontal anti-current propulsion.
[0032] In the step S1), preferably, the volume change of the AUV is calculated according to the density value of the target depth of the mission sea area, so that the adjustment amount of the buoyancy adjustment unit under the corresponding density can be calculated. Further, the AUV is trimmed according to the seawater density, that is, by adding or reducing the counterweight at the front and rear sections of the AUV, the center of gravity and the center of buoyancy are consistent, and the gravity is equal to the buoyancy. Assuming that the mass of the AUV at this time is m, the formula for solving the volume change of the AUV is,
[0033]
[0034] Where: 1 is the seawater density during trimming, ρ 2 The seawater density at the target depth in the mission sea area;
[0035] The formula for calculating the oil volume in the oil sac is obtained from formula (1):
[0036]
[0037] Where: P 0 is the neutral oil volume, V F The total amount of oil in the buoyancy control unit return oil system.
[0038] After inputting the calculated oil volume in the oil sac, the AUV can dive to the area near the target depth, realizing the rough depth control of the AUV at the target depth.
[0039] For further information, see Figure 2 In the step S2), when the target depth deviation value |Δd|≥h is determined according to the depth data fed back by the depth sensor, the depth adjustment control is triggered, where h is the depth deviation range. The formula for calculating the output pitch value is:
[0040]
[0041] Wherein, u(t) represents the output pitch value; Indicates the difference between the system feedback pitch value and the target pitch value; K is a constant; D com represents the target depth; D(t) represents the feedback value of the depth sensor; Indicates the proportional coefficient of pitch PID; K DP Indicates the scaling factor of the depth PID.
[0042] The main controller determines whether the equipment is too deep or too shallow based on the positive or negative situation of Δd, and inputs the target pitch to the attitude adjustment controller. The control module adopts a dual closed-loop control algorithm. The inner loop is pitch control, which uses the traditional PID control method. The outer loop is depth sensor feedback, which only uses a proportional link to compare the target depth with the real-time depth until the AUV reaches the target depth.
[0043] See you next time Figure 2 Furthermore, in step S3), according to the positive or negative situation of the output pitch value, the main controller controls the pitch motor to drive the battery pack to move longitudinally, so that the AUV presents a head-up or head-down posture. With target pitch value At the same time, the main thruster is turned on to reduce the response time of the entire depth adjustment process. During this period, the pitch of the AUV is gradually adjusted to the target pitch and the depth is fine-tuned by raising or lowering the head until the main thruster is turned off at Δd = 0. During this process, the equipment moves forward in a wave-like manner to adjust the depth.
[0044] Furthermore, in the step S4), the target pitch value As the system input, that is, the input of the AUV operation program, the AUV is adjusted to a horizontal state as a whole and the anti-current propulsion at a horizontal fixed depth is started.
[0045] The present invention can realize the depth control of the micro AUV in an underwater anti-current environment and enable it to have the stability of long-term local operation at a depth of 0 to 300 meters underwater, and has high accuracy, which is suitable for some detection tasks with higher requirements, thereby achieving the purpose of the invention.
Claims
1. A depth control method for underwater anti-current motion of a micro-AUV, characterized in that: The steps include: S1) calculating and setting the oil volume of the oil sac at the target depth according to the AUV volume change obtained by the seawater density difference; S2) determining the adjustment method based on the data returned by the depth sensor, and outputting the target pitch value through the PID control algorithm; S3) controlling the pitch motor and the thruster to make the AUV advance in a wave-like manner to perform depth fine-tuning, and turning off the thruster after reaching the target depth; S4) Control the pitch motor to level the AUV and then perform horizontal anti-current propulsion.
2. The depth control method for underwater anti-current motion of a micro-AUV according to claim 1 is characterized in that: In the step S1), the AUV is balanced according to the seawater density. At this time, the gravity is equal to the buoyancy. Assuming the mass of the AUV is m, the formula for calculating the volume change of the AUV is: Where: ρ1 is the seawater density during trimming, ρ2 is the seawater density at the target depth in the mission area; The formula for calculating the oil volume in the oil sac is obtained from formula (1): Where: P0 is the amount of neutral oil, V F The total amount of oil in the buoyancy control unit return oil system.
3. The depth control method for underwater anti-current motion of a micro-AUV according to claim 1 is characterized by: In the step S2), the depth adjustment control is triggered when the deviation value of the target depth |Δd|≥h is determined according to the data fed back by the depth sensor, where h is the depth deviation range. The formula for calculating the output pitch value is: Wherein, u(t) represents the output pitch value; Indicates the difference between the system feedback pitch value and the target pitch value; K is a constant; D com represents the target depth; D(t) represents the feedback value of the depth sensor; Indicates the proportional coefficient of pitch PID; K DP Indicates the scaling factor of the depth PID.
4. The depth control method for underwater anti-current motion of a micro-AUV according to claim 1 is characterized by: In the step S3), according to the positive or negative situation of the output pitch value, the main controller controls the pitch motor to drive the battery pack to move longitudinally, so that the AUV presents a head-up or head-down posture; And during the adjustment process, when the system feedback pitch value φ(t) and the target pitch value φ(d) have the same sign, the main thruster is turned on to reduce the response time of the entire depth adjustment process. During this process, the AUV performs depth adjustment in the form of wave-like advancement.
5. The depth control method for underwater anti-current motion of a micro-AUV according to claim 1 is characterized by: In the step S4), the target pitch value φ d = 0 as the system input, so that the AUV is adjusted to a horizontal state again, and the horizontal fixed depth anti-current propulsion is started.