Underwater vehicle depth control method based on water injection and drainage

Abstract

The invention discloses an underwater vehicle depth control method based on water injection and drainage, and belongs to the technical field of depth control of underwater equipment, a motion control method shown by # imgabs0 # is constructed to realize vertical accurate control, the influence of seawater density change and hull deformation is taken into account, the residual static load can be adaptively adjusted according to the change of an operation task, and the depth of the underwater vehicle is controlled. A water injection and drainage control instruction can be calculated and generated in real time according to sensor information of the underwater vehicle, and automatic depth control over the underwater vehicle is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of depth control of underwater equipment, and more specifically, relates to a depth control method of an underwater submersible based on injection and drainage. Background Art

[0002] With the continuous development of artificial intelligence, automatic control, computer simulation and other technologies, underwater submersible technology has also made significant progress. In the complex underwater environment that is difficult for many people to access, the role of underwater submersibles is becoming increasingly significant. Underwater submersibles have developed into an important tool for completing underwater operations. As a strongly coupled nonlinear system, the study of underwater submersible control methods needs to focus on control quality.

[0003] There is a great need for depth control when underwater submersibles are carrying out operational tasks. Due to the complex and changeable marine environment, for underwater submersibles equipped with depth adjustment water tanks, it is a very effective way to adjust the vertical residual static load of the submersible in real time by controlling injection and drainage, which can save limited electric energy. However, the operator is required to independently determine the total amount of injection and drainage and the timing of injection and drainage based on information such as depth deviation and density change, which puts high demands on the operator. Previously, an automatic hovering control algorithm for underwater submersibles based on injection and drainage was designed, which solved the basic problems of automatic depth control based on injection and drainage. However, there are many control parameters, the influence of residual static load is not considered, resulting in low control accuracy, and the integral control is not introduced, resulting in steady-state errors. Summary of the invention

[0004] In view of the problems that the commonly used control methods for controlling the injection and drainage depth of underwater submersibles have complex structures, many control parameters that need to be adjusted, the control accuracy needs to be further improved, and there are steady-state errors, the present invention proposes an underwater submersible depth control method based on injection and drainage, which adopts an improved sub-S-type function instead of the classic sigmoid function to improve the control response, takes into account the adaptive adjustment of the residual static load due to changes in seawater density and hull deformation, and realizes precise depth control by controlling the opening and closing of pump valves to adjust the amount of water injected and discharged in real time, thereby being suitable for engineering applications.

[0005] To achieve the above object, the present invention provides a method for controlling the depth of an underwater submersible based on injection and drainage, comprising: constructing a motion control method shown in formula (1) to achieve precise vertical control, where u is the output information of the controller, representing the force required for the vertical degree of freedom, and has been normalized; tanh() is a tangent function, To improve the sub-S-type function, B is the integral control term, f is the force required for the vertical degree of freedom; F max is the maximum force that can be provided by the vertical degree of freedom, The estimated static loads include forces and moments, reflecting the adaptability of single task state changes.

[0006]

[0007] In some optional embodiments, in formula (1), A is defined as shown in formula (2), exp() is an exponential function, and e is is the input information of the depth controller, which represents the depth deviation and the depth deviation change rate (i.e., vertical rate), and has been normalized; k1 and k2 are the deviation e and the deviation change rate, respectively. The control parameters,

[0008]

[0009] In some optional embodiments, in formula (1), B is defined as shown in formula (3), is an intelligent integral term, that is, when e(t) is less than the set threshold, an integral term is introduced, and when e(t) is greater than the set threshold, the integral term is cancelled. This method can effectively solve the integral saturation problem and reduce the overshoot while eliminating the steady-state error; k I Indicates the integral adjustment parameter.

[0010]

[0011] In some optional embodiments, in formula (1), the definition As shown in formula (4), z is the depth and R is the residual static load of the submersible.

[0012]

[0013] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0014] 1. The improved sub-S-type function is used instead of the classic sigmoid function to improve the control response; 2. Through the control item Taking into account the adaptive adjustment of the residual static load such as density change and hull deformation, no human intervention is required; 3. By controlling the opening and closing of the pump valve and adjusting the amount of water injected and discharged, high-precision depth control can be achieved; 4. The present invention realizes automatic depth control of underwater submersibles based on injection and discharge, and the depth control accuracy can reach within ±0.5m, realizing high-precision depth control, which can meet the needs of actual engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an automatic control principle diagram provided by an embodiment of the present invention;

[0016] Figure 2 It is an automatic control flow chart provided by an embodiment of the present invention;

[0017] Figure 3 It is a schematic diagram of a simulation experiment platform provided by an embodiment of the present invention;

[0018] Figure 4 It is a motion control simulation curve diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] The specific embodiments of the present invention are as follows Figure 1 to Figure 4 , the present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 This is the automatic control principle diagram. When performing depth position control, the set value is the target depth, the measured value is the actual depth measured by the depth sensor, the deviation is the difference between the target depth and the actual depth, the controller is the depth position controller, the control signal is the command to open and close the pump valve, the actuator is the pump valve, the controlled medium is the amount of water injected or discharged, the external disturbance refers to the increased current disturbance, the controlled parameter is the depth, and the sensor is the depth sensor.

[0022] Figure 2 This is an automatic control flow chart. When performing automatic depth control, first set the target value, then initialize the control parameters of the controller, and then solve the controller to obtain the time when the pump valve should be opened or closed. The pump valve is opened and closed to achieve water injection and drainage, thereby changing the difference between gravity and buoyancy. The change in the difference between gravity and buoyancy causes the sensor data to be updated accordingly, and determines whether closed-loop control needs to be continued based on the comparison between the current value and the target value.

[0023] The following simulation experiment is carried out using a certain underwater submersible as an example. The control parameters are selected as k1=1.2, k2=1.8, k I =0.45. Considering that different tasks require different sensors and equipment, the control items The state change of a single task is customized and adapted. In the embodiment, the selection is made according to formula (4).

[0024] Substituting k1=1.2, k2=1.8 into equation (2), we get equation (5):

[0025]

[0026] K I =0.45 Substitute into formula (3) and we get formula (6)

[0027]

[0028] Build a digital simulation platform (such as Figure 3 As shown in FIG. 1 ). Assume that the underwater submersible is located in a uniform density layer, completes the initial balance adjustment of buoyancy and gravity, the initial depth position is 5m from the target depth, there is an ocean current, the ocean current velocity is 0.1m / s, and the flow direction is 5°. The underwater submersible depth automatic control curve in this embodiment is as follows: Figure 4 In this embodiment, a method for controlling the depth of an underwater submersible based on injection and drainage is applied. The results show that automatic depth control is achieved. The depth control of the proposed control method has basically no overshoot and oscillation, and the steady-state deviation of the depth is controlled within the range of ±0.5m.

[0029] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0030] It will be easily understood by those skilled in the art that 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling the depth of an underwater submersible based on water injection and drainage, characterized in that: include: Constructed by The motion control method shown is used to achieve precise vertical control, where u is the output information of the controller, indicating the force required for the vertical degree of freedom; tanh() is the tangent function, To improve the sub-S-type function, B is the integral control term, and f is the force required for the vertical degree of freedom; F max is the maximum force that can be provided by the vertical degree of freedom, is the estimated static load including forces and moments.

2. The method according to claim 1, characterized in that Among them, exp() is the exponential function, e and is the input information of the depth controller, representing the depth deviation and the rate of change of the depth deviation respectively; k1 and k2 are the deviation e and the rate of change of the deviation respectively control parameters.

3. The method according to claim 2, characterized in that in, is an intelligent integral term, that is, when e(t) is less than the set threshold, the integral term is introduced, and when e(t) is greater than the set threshold, the integral term is cancelled; k I represents the integral adjustment parameter, and t1 represents the time.

4. The method according to claim 3, characterized in that Where z is the depth and R is the residual static load of the submersible.

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