Control method, control system, and apparatus for underwater robots

Abstract

This invention relates to the field of attitude control for underwater robots, and more specifically to control methods, control systems, and apparatus for underwater robots. [Solution] The present invention includes comparing the motion tendencies of an underwater robot between different directions based on motion direction progression elements to obtain a motion state, constructing a progression sequence for the main mechanical motion direction of the underwater robot, analyzing the progress in the main mechanical motion direction within a preset local time range in the progression sequence for the main mechanical motion direction, comparing abnormal changes in motion direction progression elements between different main mechanical motion directions to obtain a category for adjustment of the core machinery, and analyzing the situation of motion direction progression elements to be adjusted within the same category for adjustment of the core machinery to perform attitude control. The present invention adapts the proportional gain of the PID controller to the requirements of the underwater environment and makes the control of the underwater robot during underwater work more accurate.

Description

Technical Field

[0001] The present invention relates to the field of attitude control of underwater robots, and specifically to a control method, control system and device for underwater robots.

Background Art

[0002] Underwater robots, also called ROVs, are widely used in fields such as ocean exploration, environmental monitoring, resource exploration, and ocean engineering. With the complexity and diversity of the underwater environment, the demand for the use of underwater robots is increasing. At present, the conventional control technology of underwater robots faces many problems such as attenuation of underwater signals, influence of hydrodynamics, and changing environmental conditions, and all of these environmental conditions require high control accuracy for underwater robots.

[0003] At present, the control operation of underwater robots is usually controlled by a PID controller. However, when using a PID controller to control an underwater robot, since the proportional gain in the PID controller is usually artificially preset and controlled, it cannot be adjusted according to external underwater environmental conditions, increasing the operation difficulty of the underwater robot and reducing the control accuracy of the underwater robot.

Summary of the Invention

[0004] The present invention provides a control method, control system and device for underwater robots, aiming to solve the existing problem that the proportional gain of the PID controller in an underwater robot is usually artificially preset and controlled, so it cannot be adjusted according to external underwater environmental conditions.

[0005] The control method for the underwater robot of the present invention uses the following technical means.

[0006] The control method for the underwater robot is as follows:

[0007] a step of obtaining motion direction progress elements in different directions at a plurality of times;

[0008] The steps include: comparing the motion tendencies of the underwater robot between different directions based on the motion direction progression elements, obtaining the motion state degree of different motion direction progression elements, selecting the main mechanical motion direction at each time from all directions according to the motion state degree, and constructing a progression sequence for the underwater robot in the main mechanical motion direction;

[0009] In a sequence of motion in the main direction of mechanical motion, the degree of motion in the main direction of mechanical motion is analyzed within a preset local time range, the degree of mechanical abnormality at different time points is obtained, the abnormal changes in motion direction elements between different main directions of mechanical motion are compared according to the degree of mechanical abnormality, and the motion direction elements are classified into categories that are subject to adjustment of the core machine.

[0010] The method includes the steps of: analyzing the conditions under which the motion direction progression elements in the same core machine category are subject to adjustment, obtaining corrective adjustment component elements, and performing attitude control of the underwater robot according to the corrective adjustment component elements.

[0011] Preferably, the method for obtaining the degree of motion is:

[0012] By setting an arbitrary direction as the target direction and an arbitrary time as the target time, the difference in the motion direction progression elements between the target direction and all overall directions at the same time is compared to obtain the degree of motion in the target direction at the target time.

[0013] Preferably, after calculating the degree of motion,

[0014] This further includes normalizing the motion state scores.

[0015] Preferably, the method for acquiring the progression sequence in the main direction of mechanical motion is:

[0016] An arbitrary time is designated as the marking time. At the marking time, the direction to which the element with the maximum degree of motion in the direction of motion belongs is designated as the principal direction of mechanical motion at the marking time. The sequence obtained by rearranging the principal directions of mechanical motion at all times in ascending order of time is designated as the progression sequence of the principal direction of mechanical motion.

[0017] Preferably, the method for obtaining the degree of machine abnormality is:

[0018] An arbitrary time is used as the reference time, a preset local time range of the reference time is obtained, the degree of progress in the main direction of machine motion within the preset local time range is analyzed, the machine attitude stability within the reference time range is obtained, and, in combination with the analysis of extreme situations in the motion tendency in the progression sequence of the main direction of machine motion at the reference time, the degree of machine abnormality at the reference time is obtained according to the machine attitude stability within the range.

[0019] Preferably, a method for obtaining the machine attitude stability within the above range is:

[0020] The stability of the motion state in the principal direction of overall mechanical motion is analyzed within a predetermined local time range, and the mechanical attitude stability in the reference time range is obtained.

[0021] Preferably, a method for obtaining the category to be adjusted for the core machine is:

[0022] The differences in the degree of motion between the main directions of mechanical motion at different times are compared, and combined with the degree of mechanical abnormality to obtain a degree of similarity between different times. Based on this degree of similarity, the elements of motion direction progression are classified into categories that are subject to adjustment of the core machine.

[0023] Preferably, the method for obtaining the correction adjustment component element is:

[0024] The differences in the change in machine abnormality between categories of core machines to be adjusted are compared to obtain a machine abnormality control time range, the cover length within the machine abnormality control time range is analyzed, and correction adjustment component elements are obtained.

[0025] A control system for an underwater robot includes a memory, a processor, and a computer program stored in the memory and executed on the processor, wherein the processor executes the computer program to realize the steps of the above method.

[0026] A control device for an underwater robot, wherein the device is

[0027] The system includes a motion direction progression element acquisition module, a machine control command analysis module, and an underwater robot control module. The motion direction progression element acquisition module is used to acquire motion direction progression elements in different directions at multiple times. The machine control command analysis module implements steps of a control method for an underwater robot by calling a computer program to obtain corrective adjustment component elements. The underwater robot control module performs attitude control of the underwater robot according to the corrective adjustment component elements.

[0028] The effects of the technical means of the present invention are as follows. Based on the motion direction progress elements, the motion tendencies between different directions of the underwater robot are compared, and the motion states of different motion direction progress elements are obtained. Among them, the motion state reflects the direction tendency of the mechanical operations of the underwater robot in each direction during underwater work, and is used to make the mechanical control operations performed by the underwater robot in different directions clearer. Then, according to the motion state, the progress of the main direction of mechanical motion within a preset local time range is analyzed to obtain the mechanical abnormality degree at different times. Among them, the mechanical abnormality degree reflects the difficulty for the underwater robot to maintain the original planned direction and perform mechanical operations, and is used to more easily observe the situation where the underwater robot is affected by the buoyancy of the external water body at different times. Finally, according to the mechanical abnormality degree, the situation to be adjusted for the motion direction progress elements is analyzed, and the attitude control of the underwater robot is performed. The present invention analyzes the influence of the water flow buoyancy received by robot parts at different times and in different directions when the underwater robot is working underwater, adaptively obtains the correction adjustment component elements, and further adjusts the proportional gain. By performing attitude control on the subsequent operations of the underwater robot by a PID controller, the proportional gain of the PID controller is adapted to the requirements of the underwater environment, and the control of the underwater robot during underwater work is made more accurate.

Brief Description of the Drawings

[0029] To more clearly explain the technical means in the embodiments of the present invention or in the prior art, the drawings that need to be used in the following description of the embodiments or the prior art are briefly described below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings from these drawings without creative labor.

[0030] [Figure 1] It is a step flowchart of a control method, a control system, and a device for an underwater robot of the present invention.

Modes for Carrying Out the Invention

[0031] To further describe in detail the technical means and effects employed by the present invention to achieve a predetermined inventive objective, the specific embodiments, structures, features, and effects of the control methods, control systems, and apparatus for underwater robots proposed based on the present invention will be described below with reference to the drawings and preferred embodiments. In the following description, different “one embodiment” or “another embodiment” does not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention.

[0033] The following describes in detail specific embodiments of the control method, control system, and apparatus for underwater robots provided by the present invention with reference to the drawings.

[0034] Referring to Figure 1, a step flowchart is shown of a control method, control system, and apparatus for an underwater robot provided by one embodiment of the present invention. The method includes the following steps.

[0035] Step S001: Obtain the motion direction progression element in different directions at multiple time points.

[0036] Currently, the control operation of underwater robots is usually controlled by a PID controller. However, when controlling an underwater robot using a PID controller, the proportional gain within the PID controller is usually manually preset and controlled. This makes it impossible to adjust the brakes according to external underwater environmental conditions, increasing the difficulty of operating the underwater robot and decreasing the control accuracy of the underwater robot.

[0037] In one specific embodiment of the present invention, as a method for acquiring the motion direction progression element, a 3-axis sensor was used to acquire acceleration elements in each direction during nearly a day of underwater work by the underwater robot, and each acceleration element was used as the motion direction progression element.

[0038] One point to pay particular attention to is that the acceleration element is sampled at a interval of 1 second per sample.

[0039] Furthermore, the 3-axis sensor can acquire acceleration elements in three directions, and each acceleration element includes both a numerical value and a direction.

[0040] As described above, the motion direction progression elements in different directions at several time points were obtained using the method described above.

[0041] Step S002: Based on the motion direction progression elements, the motion tendencies of the underwater robot in different directions are compared, the motion state degree of the different motion direction progression elements is obtained, and according to the motion state degree, the main direction of mechanical motion at each time is selected from all directions, and a progression sequence of the underwater robot in the main direction of mechanical motion is constructed.

[0042] Furthermore, when an underwater robot performs work underwater, the surrounding water flow varies to different degrees in accordance with the robot's movements, and the buoyancy of the water acting on the underwater robot from each direction fluctuates with the water flow. This creates a certain resistance to the robot's planned maneuvers, hindering its movement tendencies and thus disrupting its motion state. Therefore, by comparing the motion tendencies of the underwater robot between different directions based on the motion direction progression element, it is possible to obtain the motion state degree for different motion direction progression elements. In particular, a higher motion state degree indicates that the motion tendency exhibited by the underwater robot in the corresponding direction at the corresponding time is more pronounced, reflecting that the underwater robot is performing a large maneuver in that direction.

[0043] Preferably, in some embodiments of the present invention, the method for obtaining the degree of motion involves setting an arbitrary direction as the target direction and an arbitrary time as the target time, comparing the difference in the direction of motion progression elements between the target direction and all overall directions at the same time, and obtaining the degree of motion in the target direction at the target time. The specific process is as follows.

[0044] The norm of the motion direction progression element in each direction at the target time was defined as the reference motion tendency component for each direction at the target time, the average value of the reference motion tendency components in all directions at the target time was defined as the total reference motion tendency component at the target time, and the normalized value of the ratio between the reference motion tendency component and the total reference motion tendency component for the target direction at the target time was defined as the degree of motion in the target direction at the target time.

[0045] It is especially important to note that, although the normalization process in this example uses the norm() function, the normalization function can be determined according to the specific implementation situation.

[0046] Furthermore, a higher degree of motion indicates a more pronounced tendency for the underwater robot to move in the corresponding direction at the corresponding time, reflecting that the underwater robot is performing a large maneuver in that direction.

[0047] The degree of motion represents, to some extent, the probability that the underwater robot will move at a single time and in a single direction. At a single time, the motion state of the underwater robot is primarily characterized jointly by the tendency of motion in each direction. In particular, the greater the probability of motion in a certain direction, the closer the underwater robot's motion state at the corresponding time, based on the representation of the overall direction, will approach that direction. Therefore, according to the degree of motion, it is possible to select the dominant mechanical motion direction at each time from all directions and construct a progression sequence of the underwater robot's dominant mechanical motion direction. This allows for the identification of the best representation of the underwater robot's dominant motion direction at different time points.

[0048] Preferably, in some embodiments of the present invention, the method for obtaining the progression sequence in the principal direction of mechanical motion is as follows: an arbitrary time is designated as the marking time; at the marking time, the direction to which the motion direction progression element with the maximum degree of motion belongs is designated as the principal direction of mechanical motion at the marking time; and the sequence obtained by rearranging the principal directions of mechanical motion at all times in ascending order of time is designated as the progression sequence in the principal direction of mechanical motion.

[0049] As described above, the progression sequence in the main direction of mechanical motion was obtained by the method described above.

[0050] Step S003: In the progression sequence of the main direction of mechanical motion, the degree of progress in the main direction of mechanical motion within a preset local time range is analyzed, the degree of mechanical abnormality at different times is obtained, and according to the degree of mechanical abnormality, the abnormal changes in the motion direction progression elements between different main directions of mechanical motion are compared, and the motion direction progression elements are classified into categories that are subject to adjustment of the core machine.

[0051] In actual underwater environments, other small organisms and microorganisms are also present, and their movements can influence the water flow to some extent. This results in a relatively rich variety of water flow conditions, which can cause the underwater robot's motion state to change abruptly at a single point in time. The timing of these abrupt changes usually does not coincide very well with the motion state within the surrounding area. Therefore, in the progression sequence of the main direction of mechanical motion, the degree of progress in the main direction of mechanical motion within a preset local time range can be analyzed to obtain the mechanical anomaly degree at a reference time at a different time. In particular, a higher mechanical anomaly degree indicates that the influence of buoyancy from the external water body on the underwater robot at the corresponding time is significant, making it more difficult for the underwater robot to maintain its intended direction and perform mechanical operations, and reflecting a higher probability of control anomalies occurring in the underwater robot at the corresponding time.

[0052] Preferably, in some embodiments of the present invention, the method for obtaining the degree of mechanical abnormality involves using an arbitrary time as the reference time, obtaining a preset local time range of the reference time, analyzing the progress of the main direction of mechanical motion within the preset local time range, obtaining the stability of the mechanical posture within the reference time range, and, in combination with an analysis of extreme situations in the motion tendency in the progression sequence of the main direction of mechanical motion at the reference time, obtaining the degree of mechanical abnormality at the reference time, according to the stability of the mechanical posture within the range. The specific process is as follows.

[0053] A number of time points T1 is set in advance, and the time period consisting of T1 time points before and after the reference time is defined as the pre-set local time range of the reference time. In this embodiment, T1=5 is used as an example, but this embodiment is not specifically limited. In particular, T1 can be determined according to the specific implementation situation.

[0054] A point to pay particular attention to is that if the number of actual time points before and after the reference time does not satisfy T1, the pre-defined local time range is obtained based on the number of actual time points before and after the reference time.

[0055] Preferably, in some embodiments of the present invention, the method for obtaining the machine attitude stability within the range involves analyzing the stability of the motion state in the principal direction of overall machine motion within a preset local time range, and obtaining the machine attitude stability within a reference time range. The specific process is as follows.

[0056] The average value of the motion state in all principal directions of mechanical motion within a predetermined local time range was defined as the mechanical attitude stability within the reference time range.

[0057] Furthermore, in the progression sequence of the main mechanical motion direction, the main mechanical motion direction in which the degree of motion is minimized, excluding the reference time, was defined as the extreme main mechanical motion direction. The absolute value of the difference in the degree of motion between the main mechanical motion direction and the extreme main mechanical motion direction at the reference time was defined as the degree of mechanical abnormality at the reference time.

[0058] Furthermore, a higher degree of mechanical abnormality indicates a more pronounced influence of buoyancy from the external water body on the underwater robot at the corresponding time, making it more difficult for the underwater robot to maintain its intended direction and perform mechanical operations. This reflects a higher probability of control malfunction occurring in the underwater robot at the corresponding time.

[0059] Preferably, in some embodiments of the present invention, the method for obtaining the categories of core machinery to be adjusted involves comparing the difference in the degree of motion between the main directions of machine motion at different times, combining this with the degree of machine abnormality to obtain a degree of similarity between different times, and classifying the motion direction elements into categories of core machinery to be adjusted according to the degree of similarity. The specific process is as follows.

[0060] Taking the principal directions of mechanical motion at any two time points as an example, the absolute value of the difference in the degree of motion of the motion-progressing element between these two principal directions of mechanical motion was defined as the directional motion difference component between these two time points, and the normalized value of the product of the directional motion difference component between these two time points and the degree of mechanical abnormality was defined as the degree of similarity between these two time points.

[0061] Two similarity thresholds T2 and T3 were set in advance, and times when the similarity threshold was greater than T2 and less than T3 were defined as robot control anomaly times. The category consisting of motion direction progression elements at all robot control anomaly times was defined as the category to be adjusted for one core machine. Times when the similarity threshold was greater than T3 were defined as robot control anomaly times. The category consisting of motion direction progression elements at all robot control anomaly times was defined as the category to be adjusted for one core machine. In particular, in this embodiment, T2=0.6 and T3=0.76 were used as examples, but this embodiment is not specifically limited. In particular, T2 and T3 can be determined according to the specific implementation situation.

[0062] As an option, in another embodiment, the specific process for obtaining the category to be adjusted for the core machine is as follows:

[0063] The degree of similarity between different time points was used as the distance metric, and hierarchical clustering was performed on the progression sequences of the main directions of machine motion according to the distance metric, yielding several clustering clusters. The category consisting of all the motion direction progression elements of the main directions of machine motion within each clustering cluster was designated as the category to be adjusted for the core machine. In particular, the process of performing hierarchical clustering according to the distance metric is a well-known aspect of hierarchical clustering algorithms, so it will not be repeated further in this embodiment. In particular, the progression sequence of the main directions of machine motion includes multiple main directions of machine motion, and each main direction of machine motion corresponds to one time point.

[0064] As described above, the categories of core machines to be adjusted were obtained using the method described above.

[0065] Step S004: Analyze the conditions for adjusting the motion direction progression elements in the same core machine category, obtain corrective adjustment component elements, and perform attitude control of the underwater robot according to the corrective adjustment component elements.

[0066] Preferably, in some embodiments of the present invention, the method for obtaining the corrective adjustment component elements involves comparing the differences in the change in machine abnormality between different core machine categories to be adjusted, obtaining a machine abnormality control time range, analyzing the cover length within the machine abnormality control time range, and obtaining the corrective adjustment component elements. The specific process is as follows.

[0067] The average value of the motion state of all motion-direction-progressing elements in the category to be adjusted for each core machine was defined as the abnormal motion component of the category to be adjusted for each core machine, and the variance of the motion state of all motion-direction-progressing elements in the category to be adjusted for each core machine was defined as the stability of the abnormal motion component of the category to be adjusted for each core machine. In particular, each category to be adjusted for each core machine contains multiple motion-direction-progressing elements, and each motion-direction-progressing element corresponds to one time point.

[0068] Furthermore, the category to be adjusted for any core machine was defined as the target adjustment category, the absolute value of the difference in abnormal motion components between the target adjustment category and each other core machine adjustment category was defined as one category abnormality difference component of the target adjustment category, the average value of all category abnormality difference components of the target adjustment category was defined as the overall category abnormality difference component of the target adjustment category, and the product of the overall category abnormality difference component, abnormal motion component, and stability of the abnormal motion component of the target adjustment category was defined as the time abnormality control degree of the target adjustment category. The time abnormality control degree of each category to be adjusted for each core machine was obtained. Within the category to be adjusted for the core machine that has the maximum time abnormality control degree, the maximum time range consisting of the times corresponding to all motion direction progression elements was defined as the machine abnormality control time range.

[0069] Furthermore, the product of the difference in the degree of motion of the motion state of the motion direction progression element within the mechanical abnormality control time range and the total number of times included in the mechanical abnormality control time range was used as a correction adjustment component element. This correction adjustment component element was input to the PID controller as a proportional adjustment coefficient, and the attitude adjustment control of the underwater robot was performed by the PID controller.

[0070] Furthermore, since the process of controlling the robot using a PID controller according to the proportional adjustment coefficient is a known technique, it will not be repeated further in this embodiment.

[0071] This embodiment is now complete.

[0072] The above embodiments are merely for illustrative purposes and not to limit the technical means of the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art will understand that it is still possible to modify the technical means described in each of the above embodiments or to replace some of their technical features with equivalents, and that such modifications or substitutions do not cause the essence of the corresponding technical means to deviate from the scope of the technical means of each embodiment of the present application, and that all such modifications or substitutions should be included within the scope of protection of the present application.

Claims

1. Steps include obtaining motion direction progression elements in different directions at multiple time points, The steps include: comparing the motion tendencies of the underwater robot between different directions based on the motion direction progression elements, obtaining the motion state degree of different motion direction progression elements, selecting the main mechanical motion direction at each time from all directions according to the motion state degree, and constructing a progression sequence for the underwater robot in the main mechanical motion direction; In a sequence of motion in the main direction of mechanical motion, the degree of motion in the main direction of mechanical motion is analyzed within a preset local time range, the degree of mechanical abnormality at different time points is obtained, the abnormal changes in motion direction elements between different main directions of mechanical motion are compared according to the degree of mechanical abnormality, and the motion direction elements are classified into categories that are subject to adjustment of the core machine. A control method for an underwater robot, comprising the steps of: analyzing the situation in which the motion direction progression elements in the same core machine are subject to adjustment are subject to adjustment; obtaining corrective adjustment component elements; and performing attitude control of the underwater robot according to the corrective adjustment component elements, As a method for acquiring the progression sequence in the principal direction of mechanical motion, An arbitrary time is designated as the marking time. At the marking time, the direction to which the element with the maximum degree of motion in the direction of motion belongs is designated as the principal direction of mechanical motion at the marking time. The sequence obtained by rearranging the principal directions of mechanical motion at all times in ascending order of time is designated as the progression sequence of the principal direction of mechanical motion. As for the method of obtaining the category to be adjusted for the core machine, The difference in the degree of motion between the main directions of mechanical motion at different times is compared, and combined with the degree of mechanical abnormality to obtain a degree of similarity between different times. Based on the degree of similarity, the elements of motion direction progression are classified into categories that are subject to adjustment of the core machine. The method for obtaining the aforementioned correction adjustment component element is as follows: A control method for an underwater robot, characterized by comparing the differences in the change in the degree of mechanical abnormality between different core machine categories to be adjusted, obtaining a mechanical abnormality control time range, analyzing the cover length within the mechanical abnormality control time range, and obtaining a corrective adjustment component element.

2. The method for obtaining the aforementioned degree of motor status is: A control method for an underwater robot according to claim 1, characterized in that an arbitrary direction is set as the target direction, an arbitrary time is set as the target time, the difference in the motion direction progression elements between the target direction and all overall directions at the same time is compared, and the degree of motion in the target direction at the target time is obtained.

3. After calculating the degree of physical activity, The control method for an underwater robot according to claim 1, further comprising performing a normalization process on the degree of motion.

4. The method for obtaining the machine abnormality level is as follows: A control method for an underwater robot according to claim 1, characterized in that an arbitrary time is used as a reference time, a preset local time range of the reference time is obtained, the progress of the main direction of mechanical motion within the preset local time range is analyzed, the stability of the mechanical posture within the reference time range is obtained, and, in combination with an analysis of extreme situations in the motion tendency in the progression sequence of the main direction of mechanical motion at the reference time, the degree of mechanical abnormality at the reference time is obtained according to the stability of the mechanical posture within the range.

5. A method for obtaining the machine attitude stability within the aforementioned range is: A control method for an underwater robot according to claim 4, characterized by analyzing the stability of the motion state in the main direction of overall mechanical motion within a preset local time range, and obtaining the mechanical attitude stability within a reference time range.

6. A control system for an underwater robot, comprising memory, a processor, and a computer program stored in the memory and executed on the processor, A control system for an underwater robot, characterized in that when the processor executes the computer program, it realizes the steps of the control method for an underwater robot described in any one of claims 1 to 5.

7. A control device for an underwater robot, comprising a forward motion direction element acquisition module, a machine control command analysis module, and an underwater robot control module, The motion direction progression element acquisition module is used to acquire motion direction progression elements in different directions at multiple times; the machine control command analysis module calls a computer program to realize the steps of the control method for an underwater robot described in any one of claims 1 to 5, and obtains a correction adjustment component element; and the underwater robot control module performs attitude control of the underwater robot according to the correction adjustment component element, characterized in that the control device for an underwater robot is used to acquire motion direction progression elements in different directions at multiple times; the machine control command analysis module calls a computer program to realize the steps of the control method for an underwater robot described in any one of claims 1 to 5, and obtains a correction adjustment component element; and the underwater robot control module performs attitude control of the underwater robot according to the correction adjustment component element.

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