Depth control method of underwater submersible based on injection and drainage

Abstract

The present invention discloses a method for controlling the depth of an underwater submersible based on injection and drainage, which belongs to the technical field of depth control of underwater equipment. The motion control method shown is constructed to achieve precise vertical control, taking into account the influence of changes in seawater density and hull deformation. The residual static load can be adaptively adjusted according to changes in operating tasks. The sensor information of the underwater submersible can be solved in real time to generate injection and drainage control instructions to achieve automatic depth control of the submersible.

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 for an underwater submersible based on injection and drainage. Background Art

[0002] With the continuous development of artificial intelligence, automatic control, and computer simulation technologies, underwater vehicle technology has also made significant progress. In the complex underwater environment, which is difficult for many personnel to access, underwater vehicles are becoming increasingly important and have become a vital tool for completing underwater operations. As a strongly coupled nonlinear system, the study of underwater vehicle control methods requires a focus on control quality.

[0003] Underwater submersibles have a large demand for depth control when carrying out operational tasks. Due to the complex and changeable marine environment, for underwater submersibles equipped with depth-regulating water tanks, real-time adjustment of the submersible's vertical residual static load through injection and drainage control is a very effective way to save limited electrical 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 places high demands on the operator. An automatic hovering control algorithm for underwater submersibles based on injection and drainage was previously 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 lack of integral control leads to 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 are complex in structure, require many control parameters 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. An improved sub-S-type function is used instead of the classic sigmoid function to improve the control response, and the adaptive adjustment of the residual static load due to changes in seawater density and hull deformation is taken into account. By controlling the opening and closing of pump valves to adjust the amount of water injected and discharged in real time, precise depth control is achieved, making it suitable for engineering applications.

[0005] To achieve the above-mentioned object, the present invention provides a method for controlling the depth of an underwater vehicle 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 load includes 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, representing the depth deviation and the depth deviation change rate (i.e., vertical rate), which have 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), definition B is as shown in formula (3), 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. This method can effectively solve the integral saturation problem, while eliminating the steady-state error and reducing the overshoot; 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. Using improved sub-S-type function instead of classic sigmoid function to improve 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, the amount of water injected and discharged is adjusted to achieve high-precision depth control; 4. The present invention realizes automatic depth control of underwater submersibles based on injection and drainage, 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 This is an automatic control principle diagram provided by an embodiment of the present invention;

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

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

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

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may 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 Figures 1 to 4 , the present invention will be further described below with reference to 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 a depth position controller, the control signal is the pump valve opening and closing instructions, the actuator is the pump valve, the controlled medium is the amount of water injected or discharged, the external disturbance refers to increased current interference, the controlled parameter is depth, and the sensor is a depth sensor.

[0022] Figure 2 The figure below is an automatic control flow chart. When performing automatic depth control, the target value is first set, followed by initialization of the controller's control parameters. The controller then calculates the time when the pump valve should open or close. Opening and closing the pump valve causes water to be filled or drained, thereby changing the difference between gravity and buoyancy. This change in the difference between gravity and buoyancy causes the sensor data to be updated. The current value is then compared with the target value to determine whether closed-loop control should continue.

[0023] The following simulation experiment is carried out using a 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 formula (2), we get formula (5):

[0025]

[0026] K I =0.45 is substituted into formula (3) to obtain formula (6)

[0027]

[0028] Build a digital simulation platform (such as Figure 3 Assume that the underwater submersible is located in a uniform density layer, completes the initial buoyancy and gravity balance adjustment, the initial depth position is 5m from the target depth, there is a current with a current velocity of 0.1m / s and a flow direction of 5°, and 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 method 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, or 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 merely 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 scope of protection of the present invention.

Claims

1. A method for controlling the depth of an underwater vehicle 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, representing 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, 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, Where z is the depth and R is the residual static load of the submersible.

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 time.

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