A low-power positioning method for underwater robots

Abstract

The present invention relates to the field of positioning power consumption regulation, and specifically to a low-power positioning method for an underwater robot. The method first obtains the indirect signals at different times generated by the survey signals of the underwater robot received each time within a preset time period before the current time, as well as the starting position and ending position of the underwater robot, and takes the moment of receiving the survey signal of the underwater robot at any time as the target moment, and obtains the state evaluation value of the target moment based on the number of indirect signals generated by the survey signal at the target moment, the change in amplitude and the difference in time, and the distance between the starting position and the ending position, and adjusts the positioning signal transmission period based on the state evaluation value of the moment when the survey signal of the underwater robot is received all times, and obtains the adjustment period of the underwater robot. After the positioning signal transmission period is adjusted by the present invention, the requirements of real-time positioning and low-power positioning can be taken into account at the same time, thereby improving the positioning performance.

Description

Technical Field

[0001] The present invention relates to the field of positioning power consumption regulation, and in particular to a low-power consumption positioning method for an underwater robot. Background Art

[0002] An underwater robot is an automated or remote-controlled device designed to perform tasks in a marine environment. In order to monitor the specific location of the underwater robot in real time, it is necessary to receive the positioning signal emitted by the underwater robot to locate the underwater robot. In order to maximize the endurance of the underwater robot and extend its working time, it is usually necessary to reduce the power consumption generated by the positioning of the underwater robot and improve its positioning performance.

[0003] In the related art, the period of positioning signal transmission of the underwater robot is usually increased to reduce the energy consumption generated by the positioning of the underwater robot and improve the positioning performance of the underwater robot. However, due to the complex underwater environment of the ocean, if the positioning signal transmission period is adjusted too much, the real-time positioning of the underwater robot in the complex environment cannot be achieved. If the positioning signal transmission period is adjusted too little, the power consumption of positioning cannot be effectively reduced. As a result, after the existing method adjusts the positioning signal transmission period, it is impossible to take into account the requirements of real-time positioning and low-power positioning at the same time, resulting in poor positioning performance of the underwater robot. Summary of the invention

[0004] In order to solve the technical problem that the existing method cannot take into account the requirements of real-time positioning and low-power positioning at the same time after adjusting the positioning signal transmission period, resulting in poor positioning performance of the underwater robot, the purpose of the present invention is to provide a low-power positioning method for an underwater robot, and the technical solution adopted is as follows:

[0005] The present invention proposes a low-power positioning method for an underwater robot, the method comprising:

[0006] Acquire the indirect signals at different times generated by the survey signals of the underwater robot received each time in a preset time period before the current time, as well as the starting position and ending position of the underwater robot;

[0007] The time corresponding to any time the underwater robot's survey signal is received is taken as the target time, the indirect signal generated by the survey signal at the target time is taken as the reference indirect signal, and the initial dangerous state value of the underwater robot at the target time is obtained according to the number of reference indirect signals, the difference in the time of each reference indirect signal, and the distribution of the amplitude of each reference indirect signal;

[0008] According to the change of the amplitude of the reference indirect signal at different times, the initial dangerous state value is adjusted to obtain the real dangerous state value of the underwater robot at the target time; according to the distance between the starting position and the ending position of the underwater robot within a preset time period, the movement state value of the underwater robot is obtained; based on the movement state value of the underwater robot and the real dangerous state value at the target time, the state evaluation value of the underwater robot at the target time is obtained;

[0009] Based on the state evaluation values ​​at the corresponding moments when the underwater robot's survey signals are received all the times, the period of the underwater robot's positioning signal transmission within a preset time period after the current moment is adjusted to obtain the adjustment period of the underwater robot.

[0010] Furthermore, the step of obtaining the initial danger state value of the underwater robot at the target time includes:

[0011] Analyze the overall level of the amplitude of all reference indirect signals to obtain the overall amplitude value at the target time;

[0012] After analyzing the amplitude dispersion of all reference indirect signals and performing negative correlation mapping, the amplitude aggregation degree at the target time is obtained;

[0013] The overall amplitude value and the amplitude concentration degree are integrated to obtain an amplitude distribution characteristic value at a target moment;

[0014] According to the difference between the times of any two reference indirect signals, the overall delay time of the target time is obtained;

[0015] According to the number of reference indirect signals, the amplitude distribution characteristic value at the target moment and the overall delay duration, the initial dangerous state value of the underwater robot at the target moment is obtained, wherein the number of reference indirect signals and the amplitude distribution characteristic value are positively correlated with the initial dangerous state value, and the overall delay duration is negatively correlated with the initial dangerous state value.

[0016] Further, obtaining the overall delay duration of the target time according to the difference between the time of any two reference indirect signals includes:

[0017] Take any two reference indirect signals as a signal group to be tested;

[0018] Obtaining an initial delay duration of each signal group to be tested according to a difference in time between two reference indirect signals in each signal group to be tested;

[0019] The overall level of the initial delay durations of all signal groups to be tested is analyzed to obtain the overall delay duration at the target moment.

[0020] Furthermore, obtaining the real danger state value of the underwater robot at the target time includes:

[0021] Based on the amplitude of the reference indirect signal, all reference indirect signals are clustered to obtain two clusters;

[0022] According to the difference in the amplitude of the reference indirect signal between the two clusters, the signal amplitude difference between the two clusters is obtained;

[0023] According to the change of the amplitude of the reference indirect signal at different times in each cluster, the signal amplitude change degree of each cluster is obtained; the signal amplitude change degrees of the two clusters are integrated to obtain the integrated change degree;

[0024] The signal amplitude difference and the comprehensive change degree are integrated and normalized to obtain the confidence of the dangerous state of the underwater robot at the target time;

[0025] The initial dangerous state value of the underwater robot at the target time is weighted by using the dangerous state confidence to obtain the real dangerous state value of the underwater robot at the target time.

[0026] Further, obtaining the signal amplitude difference between two clusters includes:

[0027] Analyze the overall level of the amplitude of all reference indirect signals in each cluster to obtain the amplitude center value of each cluster;

[0028] According to the difference of the amplitude center values ​​between the two clusters, the signal amplitude difference between the two clusters is obtained.

[0029] Further, obtaining the degree of change of the signal amplitude of each cluster includes:

[0030] Taking any cluster as the target cluster, and taking the sequence formed by all reference indirect signals in the target cluster in time order as the signal sequence of the target cluster;

[0031] Taking any two adjacent reference indirect signals in the signal sequence as a reference signal group, and obtaining the amplitude variation of each reference signal group according to the difference between the amplitudes of the two reference indirect signals in each reference signal group;

[0032] The overall level of amplitude variation of all reference signal groups is analyzed to obtain the degree of signal amplitude variation of the target cluster.

[0033] Furthermore, the step of obtaining the movement state value of the underwater robot includes:

[0034] The distance between the starting position and the ending position of the underwater robot is normalized to obtain a moving state value of the underwater robot.

[0035] Furthermore, obtaining the state evaluation value of the underwater robot at the target time includes:

[0036] The movement state value of the underwater robot and the real danger state value at the target time are integrated and normalized to obtain the state evaluation value of the underwater robot at the target time.

[0037] Further, obtaining the adjustment period of the underwater robot includes:

[0038] Based on the state evaluation values ​​at the corresponding moments when the survey signals of the underwater robot are received all times, an overall state evaluation value of the underwater robot within a preset time period after the current moment is obtained;

[0039] The difference between the preset maximum period and the preset minimum period of the positioning signal transmitted by the underwater robot is used as the period adjustment limit value of the underwater robot;

[0040] Using the overall state evaluation value, weighting the period adjustment limit value of the underwater robot to obtain the period adjustment amount of the underwater robot;

[0041] The difference between the preset maximum period of the positioning signal transmitted by the underwater robot and the period adjustment amount is used as the adjustment period of the underwater robot.

[0042] Furthermore, the obtaining of the overall state evaluation value of the underwater robot within a preset time period after the current moment includes:

[0043] Performing time series prediction processing on the state evaluation values ​​at the corresponding moments when all the survey signals of the underwater robot are received, to obtain a preset number of predicted state evaluation values;

[0044] The overall level of all the predicted state evaluation values ​​is analyzed to obtain the overall state evaluation value of the underwater robot within a preset time period after the current moment.

[0045] The present invention has the following beneficial effects:

[0046] The present invention takes into account that after the existing method adjusts the positioning signal transmission period, it is impossible to take into account the needs of real-time positioning and low-power positioning at the same time, which makes the positioning performance of the underwater robot poor. Therefore, the indirect signals at different times generated by the underwater robot's survey signal received each time in the preset time period before the current moment are first obtained, and the starting position and the ending position of the underwater robot in the preset time period are obtained at the same time. Considering that the positioning signal transmission period depends on the environmental characteristics of the underwater robot, underwater obstacles will cause the survey signal emitted by the underwater robot to produce a multipath effect, then the number and amplitude of the indirect signals generated by the survey signal at the target moment and the time delay characteristics of the indirect signals can reflect the environmental conditions of the underwater robot. Therefore, the initial dangerous state value can be used to preliminarily reflect the underwater robot's environmental conditions at the target moment. Taking into account the degree of danger of the environment in which the underwater robot is located, and considering that the seabed and the sea surface may cause misjudgment of the environmental conditions of the underwater robot, the initial danger state value is adjusted, and the real danger state value is used to accurately reflect the degree of danger of the environment in which the underwater robot is located at the target time. At the same time, the movement state value is used to reflect the movement of the underwater robot within a preset time period. Considering that the more dangerous the environment in which the underwater robot is located and the more obvious its movement characteristics are, it means that while positioning it with low energy consumption, more attention should be paid to its real-time positioning. On the contrary, it means that while realizing its positioning, more attention can be paid to its low-energy positioning. Therefore, the period of positioning signal transmission can be adjusted through the state evaluation value, so that the underwater robot can transmit positioning signals with the adjusted period to meet the needs of real-time positioning and low-power positioning at the same time, thereby improving the positioning performance of the underwater robot. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A flow chart of a low-power positioning method for an underwater robot provided by an embodiment of the present invention;

[0049] Figure 2 A flow chart of a method for obtaining an initial dangerous state value of an underwater robot at a target time provided by an embodiment of the present invention;

[0050] Figure 3 A flow chart of a method for obtaining a real dangerous state value of an underwater robot at a target time provided by an embodiment of the present invention;

[0051] Figure 4A flow chart of a method for obtaining an adjustment period of an underwater robot provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the low-power positioning method of an underwater robot proposed by the present invention, its specific implementation method, structure, features and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0053] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0054] The specific scheme of the low-power positioning method for an underwater robot provided by the present invention is described in detail below with reference to the accompanying drawings.

[0055] See also Figure 1 , which shows a flow chart of a low-power positioning method for an underwater robot provided by an embodiment of the present invention, the method comprising:

[0056] Step S1: Acquire the indirect signals at different times generated by the underwater robot's survey signals received each time within a preset time period before the current time, as well as the starting position and ending position of the underwater robot.

[0057] An underwater robot is an automated or remote-controlled device designed to perform tasks in a marine environment. In order to monitor the specific position of the underwater robot in real time, it is necessary to receive a positioning signal emitted by the underwater robot to achieve positioning of the underwater robot. Since positioning the underwater robot consumes a lot of energy, in order to maximize the endurance of the underwater robot and extend its working time, it is usually necessary to reduce the power consumption generated by positioning the underwater robot. In related technologies, the energy consumption generated by positioning the underwater robot is usually reduced by increasing the period of positioning signal transmission of the underwater robot. However, due to the complex underwater environment of the ocean, if the adjustment of the positioning signal transmission period is too large, the real-time positioning of the underwater robot in a complex environment cannot be achieved. If the adjustment of the positioning signal transmission period is too small, the positioning power consumption cannot be effectively reduced. As a result, after the existing method adjusts the positioning signal transmission period, it is impossible to simultaneously take into account the requirements of real-time positioning and low-power positioning. Therefore, an embodiment of the present invention proposes a low-power positioning method for an underwater robot to solve this problem.

[0058] In the process of performing tasks, underwater robots usually emit two kinds of signals. One is a survey signal, which is used to provide detailed information on the seabed topography and marine environment, and the other is a positioning signal, which is used to realize the positioning of the underwater robot. After the underwater robot emits these two signals, the terminal signal receiver receives and analyzes the signals. In addition, due to the complex marine terrain environment and the presence of many obstacles, reflection or refraction and other phenomena will occur during the signal propagation process, thereby generating a multipath effect. When the underwater robot transmits a signal, the signal receiver first receives the direct signal, and after a certain time delay, it will also receive multiple indirect signals at different times. Among them, compared with the direct signal, the indirect signal has a longer propagation distance, and there is a certain time delay for it to reach the signal receiver. At the same time, there are differences in the propagation distances between the indirect signals after reflection or refraction, resulting in different times for different indirect signals to arrive at the signal receiver, that is, there is also a delay in the time for each indirect signal to arrive at the signal receiver. It should be noted that the time delay between the direct signal and each indirect signal generated under the multipath effect is very small, and the scale is usually between nanoseconds and microseconds.

[0059] Therefore, the embodiment of the present invention first uses the signal receiver of the underwater robot terminal to receive the non-direct signals at different times generated by the underwater robot each time it transmits a survey signal within a preset time period before the current moment, and at the same time uses the signal receiver to receive the positioning signal transmitted by the underwater robot within the preset time period before the current moment, and uses the signal analysis system of the terminal to analyze the positioning signal to realize the positioning of the underwater robot, obtain multiple position information of the underwater robot within the preset time period before the current moment, and select the starting position and ending position of the underwater robot within the preset time period before the current moment, the starting position is the position of the underwater robot at the first moment within the preset time period, and the ending position is the position of the underwater robot at the last moment within the preset time period, which can also be considered as the position at the current moment, wherein the starting position and the ending position are specifically represented by three-dimensional coordinate points.

[0060] The value range of the preset time period is [1,5], in minutes. In one embodiment of the present invention, the preset time period is set to 2 minutes. The specific value of the preset time period can also be set by the implementer according to the specific implementation scenario, which is not limited here.

[0061] It should be noted that the period of transmitting the positioning signal mentioned in the embodiment of the present invention does not refer to the period of the positioning signal itself, but refers to the underwater robot sending a positioning signal at a certain time interval.

[0062] Step S2: The moment corresponding to any time the underwater robot's survey signal is received is taken as the target moment, and the indirect signal generated by the survey signal at the target moment is taken as the reference indirect signal. According to the number of reference indirect signals, the difference in the moments of each reference indirect signal, and the distribution of the amplitude of each reference indirect signal, the initial dangerous state value of the underwater robot at the target moment is obtained.

[0063] Considering that the period of the underwater robot's positioning signal transmission depends on the characteristics of the environment in which the underwater robot is located, when there are many underwater obstacles around the underwater robot, it means that it is in a more complex and dangerous environment. At this time, it is necessary to appropriately reduce the period of positioning signal transmission to ensure the real-time positioning of the underwater robot in a dangerous environment and avoid accidents. When there are fewer or basically no underwater obstacles around the underwater robot, it means that it is in a relatively safe environment. At this time, it is necessary to appropriately increase the period of positioning signal transmission to achieve low-energy positioning and increase the endurance of the underwater robot.

[0064] Since the survey signal can be received multiple times within the preset time period before the current moment, each time a survey signal, i.e. a direct signal, is received, after a certain time delay, the indirect wave signals generated by the survey signal at different times under the multipath effect can be received. Therefore, the moment corresponding to any time the survey signal of the underwater robot is received can be first taken as the target moment, and the indirect signal generated by the survey signal at the target moment can be taken as the reference indirect signal. At this time, the moment corresponding to each reference indirect signal is later than the target moment, which is convenient for the subsequent analysis of the environmental characteristics of the underwater robot at the target moment based on the characteristics of the reference indirect signal.

[0065] Underwater obstacles will cause the survey signal emitted by the underwater robot to have a multipath effect, thereby generating multiple indirect signals. In addition, the different numbers of underwater obstacles around the underwater robot and the different distances between the obstacles and the underwater robot will result in different numbers, energies and time delays of indirect signals received by the signal receiver. Specifically, the more underwater obstacles there are around the underwater robot, the more obvious the multipath effect is, the more indirect signals the signal receiver receives, and the closer the distance between the obstacles and the underwater robot is, the less energy the indirect signal loses during propagation, that is, the energy of the indirect signal received by the signal receiver is larger, and the time delay between the indirect signals received by the signal receiver is smaller. Therefore, the reference indirect signal can be used to obtain the indirect signal. The difference in the number of direct signals and the time of each reference indirect signal is analyzed, and the amplitude of the reference indirect signal is used to reflect its energy size. Then, combined with the distribution characteristics of the amplitude of each reference indirect signal, the initial dangerous state value obtained can be used to preliminarily reflect the degree of danger of the environment in which the underwater robot is located at the target time. The initial dangerous state value can be further adjusted later to improve the accuracy of the analysis of the environmental situation of the underwater robot at the target time, and then the period of the underwater robot positioning signal emission is adaptively adjusted to achieve low-energy positioning while also being able to position the underwater robot in real time. The amplitude of the signal is the distance between the highest peak and the lowest peak of the signal. The larger the amplitude of the signal, the greater its energy. The amplitude of the signal is an existing concept and will not be elaborated here.

[0066] Preferably, in one embodiment of the present invention, the method for obtaining the initial dangerous state value of the underwater robot at the target time specifically includes:

[0067] See also Figure 2 , which shows a flow chart of a method for obtaining an initial dangerous state value of an underwater robot at a target time provided by an embodiment of the present invention.

[0068] Step S201: Analyze the overall level of the amplitude of all reference indirect signals to obtain the overall amplitude value at the target moment; analyze the discrete degree of the amplitude of all reference indirect signals and perform negative correlation mapping to obtain the amplitude aggregation degree at the target moment; combine the overall amplitude value and the amplitude aggregation degree to obtain the amplitude distribution characteristic value at the target moment.

[0069] From the above analysis, it can be seen that when the distance between the obstacle and the underwater robot is closer, that is, when the environment in which the underwater robot is located is more complex and dangerous, the energy loss of the reference indirect signal corresponding to the survey signal at the target time during the propagation process is smaller, that is, the energy of the reference indirect signal received by the signal receiver is higher. Therefore, the overall level of the amplitude of all reference indirect signals can be analyzed to obtain the overall amplitude value at the target time. The larger the overall amplitude value, the higher the overall level of the reference indirect signal energy corresponding to the survey signal at the target time, and the amplitude of all reference indirect signals can be analyzed. After analyzing the discrete degree of the amplitude and performing negative correlation mapping, the amplitude aggregation degree at the target moment is obtained. The greater the amplitude aggregation degree, the more concentrated the amplitude of the reference indirect signal is. Then, the overall amplitude value and the amplitude aggregation degree are combined to obtain the amplitude distribution characteristic value at the target moment. The larger the amplitude distribution characteristic value, the higher the overall level of the amplitude of the reference indirect signal is, and the high amplitude values ​​are more concentrated, indicating that the energy of all reference indirect signals is generally high, which further indicates that the environment in which the underwater robot is located at the target moment is more complex and dangerous, providing a data basis for the subsequent calculation of the initial dangerous state value.

[0070] In an embodiment of the present invention, the average value or median of the amplitudes of all reference indirect signals may be used as the overall amplitude value at the target moment to implement analysis of the overall level of the amplitudes of all reference indirect signals, which is not limited here.

[0071] In an embodiment of the present invention, the range, variance or standard deviation of the amplitude of all reference indirect signals can be used as the amplitude dispersion degree at the target moment to analyze the amplitude dispersion degree of all reference indirect signals, and negative correlation functions such as inverse proportional functions can be used to achieve negative correlation mapping of the amplitude dispersion degree, thereby obtaining the amplitude aggregation degree at the target moment, which is not limited here.

[0072] In the embodiment of the present invention, the product value or the sum value of the overall amplitude value and the amplitude concentration degree may be used as the amplitude distribution characteristic value at the target moment to achieve a combination of the two, which is not limited here.

[0073] The expression of the amplitude distribution characteristic value at the target time can be specifically, for example, as follows:

[0074]

[0075] Among them, B represents the amplitude distribution characteristic value at the target time; A n represents the amplitude of the nth reference indirect signal corresponding to the survey signal at the target time; N represents the number of reference indirect signals; represents the overall amplitude value at the target moment; σ represents the amplitude dispersion at the target moment; Indicates the degree of amplitude concentration at the target moment; ε1 represents the preset first adjustment parameter to prevent the denominator from being 0. The value range of ε1 is [0.001, 0.01]. In one embodiment of the present invention, ε1 is set to 0.01. The specific value of ε1 can also be set by the implementer according to the specific implementation scenario, which is not limited here.

[0076] Step S202: Obtain the overall delay duration of the target time according to the difference between the times of any two reference indirect signals.

[0077] From the above analysis, it can be seen that the closer the distance between the obstacle and the underwater robot is, that is, when the environment in which the underwater robot is located is more complex and dangerous, the time delay between the reference indirect signals is smaller. Therefore, the overall delay duration at the target moment can be obtained based on the difference in the moments of any two reference indirect signals. The smaller the overall delay duration, the smaller the time delay between the reference indirect signals, which further indicates that the environment in which the underwater robot is located at the target moment is more dangerous, providing a data basis for the subsequent calculation of the initial dangerous state value.

[0078] Preferably, in one embodiment of the present invention, the method for obtaining the overall delay duration of the target time specifically includes:

[0079] First, any two reference indirect signals are taken as a signal group to be tested; based on the difference in the moments of the two reference indirect signals in each signal group to be tested, the initial delay duration of each signal group to be tested is obtained. The smaller the initial delay duration is, the smaller the degree of time delay between the two reference indirect signals in each signal group to be tested and the arrival of the signal receiver is.

[0080] In one embodiment of the present invention, the absolute value of the difference between the moments of two reference indirect signals in each signal group to be tested may be used as the initial delay duration of each signal group to be tested, so as to analyze the difference between the two.

[0081] Then, the overall level of the initial delay durations of all the signal groups to be tested is analyzed to obtain the overall delay duration at the target moment.

[0082] In the embodiment of the present invention, the average or median of the initial delay durations of all signal groups to be tested may be used as the overall delay duration at the target moment to implement an overall level analysis of the initial delay durations of all signal groups to be tested, which is not limited here.

[0083] The expression of the overall delay duration of the target time can be specifically, for example, as follows:

[0084]

[0085] Where L represents the overall delay time of the target time; t mand t′ m They represent the time instants of two reference indirect signals in the mth signal group to be tested; M represents the number of signal groups to be tested; |t m ―t′ m | represents the initial delay time of the mth signal group to be tested.

[0086] Step S203: According to the number of reference indirect signals, the amplitude distribution characteristic values ​​at the target moment and the overall delay duration, the initial dangerous state value of the underwater robot at the target moment is obtained, wherein the number of reference indirect signals and the amplitude distribution characteristic values ​​are positively correlated with the initial dangerous state value, and the overall delay duration is negatively correlated with the initial dangerous state value.

[0087] From the above analysis, it can be seen that the more underwater obstacles there are around the underwater robot and the more obvious the multipath effect is, the more reference indirect signals there are. At the same time, the larger the amplitude distribution eigenvalue is and the smaller the overall delay time is, the more dangerous the environment of the underwater robot is at the target time. Therefore, the initial dangerous state value of the underwater robot at the target time can be obtained according to the number of reference indirect signals, the amplitude distribution eigenvalue at the target time and the overall delay time. Among them, the number of reference indirect signals and the amplitude distribution eigenvalue are positively correlated with the initial dangerous state value, and the overall delay time is negatively correlated with the initial dangerous state value.

[0088] It should be noted that a positive correlation means that the dependent variable will increase as the independent variable increases, and the dependent variable will decrease as the independent variable decreases. A negative correlation means that the dependent variable will decrease as the independent variable increases, and the dependent variable will increase as the independent variable decreases.

[0089] The expression of the initial dangerous state value of the underwater robot at the target time can be specifically, for example, as follows:

[0090]

[0091] Wherein, D represents the initial dangerous state value of the underwater robot at the target moment; N represents the number of reference indirect signals; B represents the amplitude distribution characteristic value at the target moment; L represents the overall delay duration at the target moment; ε2 represents the preset first adjustment parameter to prevent the denominator from being 0, and the value range of ε2 is [0.001, 0.01]. In one embodiment of the present invention, ε2 is set to 0.01. The specific value of ε2 can also be set by the implementer according to the specific implementation scenario, which is not limited here.

[0092] Step S3: According to the change of the amplitude of the reference indirect signal at different times, the initial danger state value is adjusted to obtain the real danger state value of the underwater robot at the target time; according to the distance between the starting position and the ending position of the underwater robot within a preset time period, the movement state value of the underwater robot is obtained; based on the movement state value of the underwater robot and the real danger state value at the target time, the state evaluation value of the underwater robot at the target time is obtained.

[0093] Because when the underwater robot is close to the normal seabed or sea surface, the survey signal emitted by the underwater robot will still have a multipath effect and generate indirect signals. Therefore, if the environmental conditions of the underwater robot are evaluated only by the initial dangerous state value obtained above, the seabed or sea surface approached by the underwater robot during normal operation will be misjudged as a dangerous environment. At the same time, considering that when the underwater robot is close to the normal seabed or sea surface, the energy lost in the propagation process of the indirect signals generated by the survey signal emitted by the underwater robot under the multipath effect is relatively close, the energy of the indirect signals received by the signal receiver is relatively close, and when the underwater robot is close to the dangerous environment, the energy of the indirect signals generated by the multipath effect is relatively close. When the underwater robot is at a dangerous seabed, such as a trench or a rift, the energy lost in the propagation process of each indirect signal generated by the multipath effect of the survey signal emitted by it is quite different. Then, the energy of each indirect signal received by the signal receiver is quite different. Therefore, the initial dangerous state value can be adjusted according to the change of the amplitude of the reference indirect signal at different times. The real dangerous state value obtained can accurately reflect the degree of danger of the environment in which the underwater robot is located at the target time. Subsequently, based on the real dangerous state value, the period of transmitting the underwater robot positioning signal can be adaptively adjusted to achieve low-energy positioning while also being able to locate the underwater robot in real time.

[0094] Preferably, in one embodiment of the present invention, the method for obtaining the real danger state value of the underwater robot at the target time specifically includes:

[0095] See also Figure 3 , which shows a flow chart of a method for obtaining a real dangerous state value of an underwater robot at a target moment provided by an embodiment of the present invention.

[0096] Step S301: clustering all reference indirect signals based on the amplitudes of the reference indirect signals to obtain two clusters.

[0097] Firstly, based on the amplitude of the reference indirect signal, all reference indirect signals are clustered to obtain two clusters. Subsequently, based on the distribution and change of the amplitude of the reference indirect signal in these two clusters, the confidence of the dangerous environment in which the underwater robot is located at the target time can be analyzed, thereby adjusting the initial dangerous state value.

[0098] In one embodiment of the present invention, a K-means algorithm is used, and the Euclidean distance or Manhattan distance between the amplitudes of each reference indirect signal is used as a distance metric to achieve clustering of the reference indirect signals. In other embodiments of the present invention, clustering may also be achieved using a clustering algorithm such as the DBSCAN algorithm, which is not limited here.

[0099] Step S302: obtaining a signal amplitude difference between the two clusters according to the difference in amplitude of the reference indirect signal between the two clusters.

[0100] From the above analysis, it can be seen that compared with performing tasks on the normal seabed or sea surface, when the underwater robot approaches a dangerous seabed such as a trench or a rift, the energy difference of each reference indirect signal received by the signal receiver is larger, that is, the difference in the amplitude of each reference direct signal is larger, then the difference in the amplitude of the reference indirect signal between the two clustering clusters after clustering is larger. Therefore, according to the difference in the amplitude of the reference indirect signal between the two clustering clusters, the signal amplitude difference between the two clustering clusters can be obtained. The larger the signal amplitude difference, the greater the overall level of difference in the amplitude of the reference indirect signal between the two clustering clusters, and thus the higher the confidence that the underwater robot is in a dangerous environment at the target time, providing a data basis for the subsequent calculation of the confidence of the dangerous state.

[0101] Preferably, in one embodiment of the present invention, a method for obtaining the signal amplitude difference between two clusters specifically includes:

[0102] The overall level of the amplitude of all reference indirect signals in each cluster is analyzed to obtain the amplitude center value of each cluster. The larger the amplitude center value, the larger the overall level of the amplitude of all reference indirect signals in each cluster.

[0103] In an embodiment of the present invention, the average value or median of the amplitude of all reference indirect signals in each cluster can be used as the amplitude center value of each cluster to achieve an overall level analysis of the amplitude of all reference indirect signals in each cluster, which is not limited here.

[0104] The greater the difference in the amplitude center values ​​between the two clusters, the greater the difference in the overall level of the amplitude of the reference indirect signal between the two clusters. Therefore, the signal amplitude difference between the two clusters can be obtained based on the difference in the amplitude center values ​​between the two clusters.

[0105] In one embodiment of the present invention, the absolute value of the difference between the amplitude center values ​​of two clusters may be used as the signal amplitude difference between the two clusters to analyze the difference between the two clusters.

[0106] The expression of the difference in signal amplitude between two clusters can be specifically, for example, as follows:

[0107]

[0108] Where E represents the difference in signal amplitude between two clusters; A (h,1) represents the amplitude of the hth reference indirect signal in one of the clusters; A (h′,2) represents the amplitude of the h′th reference indirect signal in another cluster; H and H′ represent the number of reference indirect signals in the two clusters respectively; and Respectively represent the amplitude center values ​​of the two clusters.

[0109] Step S303: obtaining the signal amplitude variation degree of each cluster according to the variation of the amplitude of the reference indirect signal at different moments in each cluster; and synthesizing the signal amplitude variation degrees of two clusters to obtain the comprehensive variation degree.

[0110] When the underwater robot approaches a dangerous seabed such as a trench or a rift, the difference in the amplitudes of the reference direct signals is large, and the degree of change in the amplitude of the reference indirect signal at different times in each cluster is greater. Therefore, the degree of change in the signal amplitude of each cluster can be obtained based on the change in the amplitude of the reference indirect signal at different times in each cluster. The greater the signal amplitude change, the greater the temporal change in the amplitude of the reference indirect signal in each cluster.

[0111] Preferably, in one embodiment of the present invention, the method for obtaining the degree of change of the signal amplitude of each cluster specifically includes:

[0112] Firstly, any cluster is taken as the target cluster, and a sequence formed by time-sorting all reference indirect signals in the target cluster is taken as the signal sequence of the target cluster, wherein the time sequence may be in ascending or descending order and is not limited here; any two adjacent reference indirect signals in the signal sequence are taken as a reference signal group, and the amplitude change of each reference signal group is obtained according to the difference in the amplitudes of the two reference indirect signals in each reference signal group. The larger the amplitude change, the greater the degree of change in the amplitudes of the two reference indirect signals in each reference signal group.

[0113] In one embodiment of the present invention, the absolute value of the difference between the amplitudes of two reference indirect signals in each reference signal group may be used as the amplitude variation of each reference signal group to analyze the difference between the two.

[0114] Furthermore, the overall level of amplitude variation of all reference signal groups is analyzed to obtain the degree of signal amplitude variation of the target cluster.

[0115] In the embodiment of the present invention, the average or median of the amplitude variation of all reference signal groups may be used as the signal amplitude variation degree of the target cluster to implement the overall level analysis of the amplitude variation of all reference signal groups, which is not limited here.

[0116] The expression of the signal amplitude variation degree of the target cluster can be specifically expressed as:

[0117]

[0118] Among them, ΔA represents the degree of change in the signal amplitude of the target cluster; A′ g and A″ g Respectively represent the amplitudes of the two reference indirect signals in the g-th reference signal group of the target cluster; G represents the number of reference signal groups of the target cluster; |A′ g ―A″ g | represents the amplitude change of the g-th reference signal group of the target cluster.

[0119] The signal amplitude variation degree of each cluster can be obtained by the same method as above.

[0120] Then, the degree of change in the signal amplitude of the two clusters can be integrated to obtain the comprehensive degree of change. The larger the comprehensive degree of change, the larger the time series change in the amplitude of the reference indirect signals in the two clusters, which further indicates that the confidence that the underwater robot is in a dangerous environment at the target time is higher, providing a data basis for the subsequent calculation of the confidence of the dangerous state.

[0121] In the embodiment of the present invention, the sum or product of the signal amplitude change degrees of two clusters may be used as the comprehensive change degree to achieve the integration of the two, which is not limited here.

[0122] Step S304: The signal amplitude difference and the comprehensive change degree are integrated and normalized to obtain the confidence level of the dangerous state of the underwater robot at the target time.

[0123] Since the greater the difference in signal amplitude between the two clusters and the greater the comprehensive change degree, the higher the confidence that the underwater robot is in a dangerous environment at the target time is, the signal amplitude difference and the comprehensive change degree can be integrated and normalized to obtain the confidence of the dangerous state of the underwater robot at the target time. The greater the confidence of the dangerous state, the higher the confidence that the underwater robot is in a dangerous environment at the target time. The initial dangerous state value can be adjusted based on the confidence of the dangerous state.

[0124] In one embodiment of the present invention, the sum or product of the signal amplitude difference and the comprehensive change degree can be used as the confidence level of the dangerous state of the underwater robot at the target time to achieve a combination of the two, which is not limited here.

[0125] In one embodiment of the present invention, the normalization processing can be specifically, for example, maximum and minimum value normalization processing, and the normalization in subsequent steps can all adopt maximum and minimum value normalization processing. In other embodiments of the present invention, other normalization methods can be selected according to the specific range of numerical values, which will not be described in detail.

[0126] The expression of the confidence level of the dangerous state of the underwater robot at the target time can be specifically expressed as:

[0127] ρ=norm(E+F)

[0128] Among them, ρ represents the confidence of the dangerous state of the underwater robot at the target moment; E represents the difference in signal amplitude between the two clusters; F represents the comprehensive degree of change; norm() represents the normalization function.

[0129] Step S305: using the dangerous state confidence, weighting the initial dangerous state value of the underwater robot at the target time, to obtain the real dangerous state value of the underwater robot at the target time.

[0130] The greater the confidence of the dangerous state, the higher the confidence of the dangerous environment in which the underwater robot is located at the target time. Therefore, the confidence of the dangerous state can be used to weight the initial dangerous state value of the underwater robot at the target time to obtain the real dangerous state value of the underwater robot at the target time. The real dangerous state value can accurately reflect the environmental conditions of the underwater robot at the target time.

[0131] The expression of the actual dangerous state value of the underwater robot at the target time can be specifically, for example, as follows:

[0132] D′=ρ×D

[0133] Where D′ represents the actual dangerous state value of the underwater robot at the target time; ρ represents the confidence of the dangerous state of the underwater robot at the target time; and D represents the initial dangerous state value of the underwater robot at the target time.

[0134] Since the period of transmitting the positioning signal of the underwater robot also depends on the movement status of the underwater robot, specifically: if the underwater robot has a relatively obvious movement feature in the preset time period before the current moment, it means that the underwater robot is in a fast-moving state in the preset time period before the current moment, then it is necessary to reduce the period of transmitting the positioning signal of the underwater robot to ensure that the position information of the fast-moving underwater robot can be monitored in real time; if the underwater robot does not have a relatively obvious movement feature in the preset time period before the current moment, it means that the underwater robot is in a slow-moving state or a stationary state in the preset time period before the current moment, then it is necessary to increase the period of transmitting the positioning signal of the underwater robot to reduce the energy consumption generated by positioning and increase the endurance of the underwater robot. Therefore, the movement state value of the underwater robot can be obtained according to the distance between the starting position and the ending position of the underwater robot in the preset time period. The larger the movement state value, the more obvious the movement feature of the underwater robot in the preset time period before the current moment. Subsequently, the period of transmitting the positioning signal of the underwater robot can be adaptively adjusted based on the movement state value.

[0135] Preferably, in one embodiment of the present invention, the method for obtaining the movement state value of the underwater robot specifically includes:

[0136] Since the longer the distance between the starting position and the ending position of the underwater robot is, the more obvious the movement characteristics of the underwater robot are in the preset time period before the current moment, the distance between the starting position and the ending position of the underwater robot can be normalized to obtain the movement state value of the underwater robot.

[0137] In one embodiment of the present invention, the Euclidean distance between the start position and the end position of the underwater robot may be used to measure the distance between the two.

[0138] Since the environmental conditions of the underwater robot at the target moment and its movement conditions in the preset time period before the current moment can both affect the adjustment of the positioning signal transmission period, the state evaluation value of the underwater robot at the target moment can be obtained based on the movement state value of the underwater robot and the actual danger state value at the target moment. The larger the state evaluation value, the more dangerous the environment in which the underwater robot is located at the target moment, and the more obvious its movement characteristics at the target moment. On the contrary, the smaller the state evaluation value, the safer the environment in which the underwater robot is located at the target moment, and the less obvious its movement characteristics at the target moment. Subsequently, based on the state evaluation value, the period of positioning signal transmission of the underwater robot in the preset time period after the current moment can be adjusted.

[0139] Preferably, in one embodiment of the present invention, a method for obtaining a state evaluation value of an underwater robot at a target time specifically includes:

[0140] The mobile state value of the underwater robot and the real dangerous state value at the target time are integrated and normalized to obtain the state evaluation value of the underwater robot at the target time.

[0141] In the embodiment of the present invention, the combination of the mobile state value of the underwater robot and the real dangerous state value at the target time can be achieved by calculating the sum or product of the two, which is not limited here.

[0142] The expression of the state evaluation value of the underwater robot at the target time can be specifically, for example, as follows:

[0143] U = norm(W + D′)

[0144] Among them, U represents the state evaluation value of the underwater robot at the target time; W represents the movement state value of the underwater robot; D′ represents the actual dangerous state value of the underwater robot at the target time; norm() represents the normalization function.

[0145] Since the signal receiver can receive the survey signal, i.e., the direct signal, emitted by the underwater robot multiple times within the preset time period before the current moment, the same method as above can be used to obtain the state evaluation value at the corresponding moment each time the survey signal of the underwater robot is received.

[0146] Step S4: Based on the state evaluation values ​​corresponding to the moments when the underwater robot's survey signals are received all the times, the period of the underwater robot's positioning signal transmission within a preset time period after the current moment is adjusted to obtain the adjustment period of the underwater robot.

[0147] The more dangerous the environment in which the underwater robot is located and the more obvious its movement characteristics are, it means that while achieving its low-energy positioning, more attention should be paid to its real-time positioning. At this time, the underwater robot can use a smaller period to transmit positioning signals. On the contrary, when the environment in which the underwater robot is located and the less obvious its movement characteristics are, it means that while achieving its positioning, more attention can be paid to its low-energy positioning to extend the battery life. At this time, the underwater robot can use a larger period to transmit positioning signals. Therefore, based on the state evaluation value corresponding to the moment when all the survey signals of the underwater robot are received, the period of the underwater robot's positioning signal transmission within a preset time period after the current moment can be adjusted, so that the underwater robot can transmit positioning signals with an adjusted period within the preset time period after the current moment to simultaneously take into account the needs of real-time positioning and low-power positioning, thereby improving the positioning performance of the underwater robot.

[0148] Preferably, in one embodiment of the present invention, the method for obtaining the adjustment period of the underwater robot specifically includes:

[0149] See also Figure 4 , which shows a flow chart of a method for obtaining an adjustment period of an underwater robot provided by an embodiment of the present invention.

[0150] Step S401: Based on the state evaluation values ​​at the corresponding moments when the underwater robot's survey signals are received all the times, the overall state evaluation value of the underwater robot within a preset time period after the current moment is obtained.

[0151] Since the preset time period before and after the current moment is short, the environmental conditions and movement conditions of the underwater robot in the preset time period before the current moment can be used to reflect the environmental conditions and movement conditions of the underwater robot in the preset time period after the current moment. Therefore, the overall state evaluation value of the underwater robot in the preset time period after the current moment can be obtained based on the state evaluation values ​​corresponding to the moments when the survey signals of the underwater robot are received all times. The larger the overall state evaluation value, the more dangerous the environment in which the underwater robot is likely to be in the preset time period after the current moment, and the more obvious the movement characteristics may be. Subsequently, the adjustment period of the underwater robot can be accurately calculated based on the overall state evaluation value.

[0152] Preferably, in one embodiment of the present invention, the method for obtaining the overall state evaluation value of the underwater robot within a preset time period after the current moment specifically includes:

[0153] The state evaluation values ​​at the corresponding moments when the survey signals of the underwater robot are received all times are processed by time series prediction to obtain a preset number of predicted state evaluation values. The predicted evaluation values ​​are used to reflect the environmental conditions and movement conditions of the underwater robot within a preset time period after the current moment. Time series prediction is a technical means well known to technicians in this field and will not be elaborated here.

[0154] The preset number has a value range of integers from 20 to 30. In one embodiment of the present invention, the preset number is set to 20. The specific value of the preset number can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0155] Then, the overall level of all predicted state evaluation values ​​is analyzed to obtain the overall state evaluation value of the underwater robot within a preset time period after the current moment.

[0156] In the embodiment of the present invention, the average value or median of all predicted state evaluation values ​​can be used as the overall state evaluation value of the underwater robot in a preset time period after the current moment to implement the overall level analysis of all predicted state evaluation values, which is not limited here.

[0157] Since the preset time period before and after the current moment is short, the environmental conditions and movement conditions of the underwater robot in the preset time period before and after the current moment are relatively similar. Therefore, in other embodiments of the present invention, time series prediction processing may not be performed, but the overall level of the state evaluation value corresponding to the moment when the survey signal of the underwater robot is received all times is directly analyzed to obtain the overall state evaluation value of the underwater robot in the preset time period after the current moment.

[0158] Step S402: taking the difference between the preset maximum period and the preset minimum period of the positioning signal emitted by the underwater robot as the period adjustment limit value of the underwater robot; using the overall state evaluation value to weight the period adjustment limit value of the underwater robot to obtain the period adjustment amount of the underwater robot; taking the difference between the preset maximum period and the period adjustment amount of the positioning signal emitted by the underwater robot as the adjustment period of the underwater robot.

[0159] Generally, in the implementation of the underwater robot positioning function, a maximum period and a minimum period are preset for the positioning signal transmission period of the underwater robot, so that the adjusted positioning signal transmission period does not exceed the maximum period and is not lower than the minimum period to ensure the normal positioning work. Therefore, the embodiment of the present invention first uses the difference between the preset maximum period and the preset minimum period of the positioning signal transmission of the underwater robot as the period adjustment limit value of the underwater robot, and uses the overall state evaluation value to weight the period adjustment limit value of the underwater robot to obtain the period adjustment amount of the underwater robot; and then uses the difference between the preset maximum period and the period adjustment amount of the positioning signal transmission of the underwater robot as the adjustment period of the underwater robot.

[0160] In one embodiment of the present invention, the preset maximum period is set to 10 seconds, and the preset minimum period is set to 2 seconds. The specific values ​​of the preset maximum period and the preset minimum period can also be set by the implementer according to the specific implementation scenario, and are not limited here.

[0161] The expression of the adjustment period of the underwater robot can be specifically expressed as:

[0162] T=T max ―Z×(T max ―T min )

[0163] Wherein, T represents the adjustment period of the underwater robot; Z represents the overall state evaluation value of the underwater robot within a preset time period after the current moment; T max Indicates the preset maximum period; T min Indicates the preset minimum period; T max ―T min Indicates the periodic adjustment limit value of the underwater robot.

[0164] After obtaining the adjustment cycle of the underwater robot, the underwater robot transmits a positioning signal in the adjustment cycle within a preset time period after the current moment, thereby achieving the requirements of both real-time positioning and low-power positioning, making the positioning performance of the underwater robot better.

[0165] In summary, the embodiment of the present invention first obtains the indirect signals at different times generated by the underwater robot's survey signal received each time within a preset time period before the current moment, and simultaneously obtains the starting position and the ending position of the underwater robot within the preset time period; the moment corresponding to any time the underwater robot's survey signal is received is taken as the target moment, and the indirect signal generated by the survey signal at the target moment is taken as the reference indirect signal, and the initial danger state value of the underwater robot at the target moment is obtained according to the number of reference indirect signals, the difference in the moments of the reference indirect signals, and the distribution of the amplitudes of the reference indirect signals; according to the different moments The initial danger state value is adjusted according to the change in the amplitude of the reference indirect signal to obtain the real danger state value of the underwater robot at the target time; the movement state value of the underwater robot is obtained according to the distance between the starting position and the ending position of the underwater robot within a preset time period; based on the movement state value of the underwater robot and the real danger state value at the target time, the state evaluation value of the underwater robot at the target time is obtained; based on the state evaluation value corresponding to the moment when the survey signal of the underwater robot is received all times, the period of the positioning signal transmission of the underwater robot within the preset time period after the current moment is adjusted to obtain the adjustment period of the underwater robot.

[0166] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0167] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A low-power positioning method for an underwater robot, characterized in that: The method comprises: Acquire the indirect signals at different times generated by the survey signals of the underwater robot received each time in a preset time period before the current time, as well as the starting position and ending position of the underwater robot; The time corresponding to any time the underwater robot's survey signal is received is taken as the target time, the indirect signal generated by the survey signal at the target time is taken as the reference indirect signal, and the initial dangerous state value of the underwater robot at the target time is obtained according to the number of reference indirect signals, the difference in the time of each reference indirect signal, and the distribution of the amplitude of each reference indirect signal; According to the change of the amplitude of the reference indirect signal at different times, the initial dangerous state value is adjusted to obtain the real dangerous state value of the underwater robot at the target time; according to the distance between the starting position and the ending position of the underwater robot within a preset time period, the movement state value of the underwater robot is obtained; based on the movement state value of the underwater robot and the real dangerous state value at the target time, the state evaluation value of the underwater robot at the target time is obtained; Based on the state evaluation values ​​at the corresponding moments when the underwater robot's survey signals are received all the times, the period of the underwater robot's positioning signal transmission within a preset time period after the current moment is adjusted to obtain the adjustment period of the underwater robot.

2. A low-power positioning method for an underwater robot according to claim 1, characterized in that: The step of obtaining the initial danger state value of the underwater robot at the target time includes: Analyze the overall level of the amplitude of all reference indirect signals to obtain the overall amplitude value at the target time; After analyzing the amplitude dispersion of all reference indirect signals and performing negative correlation mapping, the amplitude aggregation degree at the target time is obtained; The overall amplitude value and the amplitude concentration degree are integrated to obtain an amplitude distribution characteristic value at a target moment; According to the difference between the times of any two reference indirect signals, the overall delay time of the target time is obtained; According to the number of reference indirect signals, the amplitude distribution characteristic value at the target moment and the overall delay duration, the initial dangerous state value of the underwater robot at the target moment is obtained, wherein the number of reference indirect signals and the amplitude distribution characteristic value are positively correlated with the initial dangerous state value, and the overall delay duration is negatively correlated with the initial dangerous state value.

3. A low-power positioning method for an underwater robot according to claim 2, characterized in that: The step of obtaining the overall delay duration of the target time according to the difference between the time of any two reference indirect signals comprises: Take any two reference indirect signals as a signal group to be tested; Obtaining an initial delay duration of each signal group to be tested according to a difference in time between two reference indirect signals in each signal group to be tested; The overall level of the initial delay durations of all signal groups to be tested is analyzed to obtain the overall delay duration at the target moment.

4. The low-power positioning method for an underwater robot according to claim 1, characterized in that: The obtaining of the real danger state value of the underwater robot at the target time comprises: Based on the amplitude of the reference indirect signal, all reference indirect signals are clustered to obtain two clusters; According to the difference in the amplitude of the reference indirect signal between the two clusters, the signal amplitude difference between the two clusters is obtained; According to the change of the amplitude of the reference indirect signal at different times in each cluster, the signal amplitude change degree of each cluster is obtained; the signal amplitude change degrees of the two clusters are integrated to obtain the integrated change degree; The signal amplitude difference and the comprehensive change degree are integrated and normalized to obtain the confidence of the dangerous state of the underwater robot at the target time; The initial dangerous state value of the underwater robot at the target time is weighted by using the dangerous state confidence to obtain the real dangerous state value of the underwater robot at the target time.

5. A low-power positioning method for an underwater robot according to claim 4, characterized in that: The obtaining of the signal amplitude difference between two clusters comprises: Analyze the overall level of the amplitude of all reference indirect signals in each cluster to obtain the amplitude center value of each cluster; According to the difference of the amplitude center values ​​between the two clusters, the signal amplitude difference between the two clusters is obtained.

6. A low-power positioning method for an underwater robot according to claim 4, characterized in that: The obtaining of the signal amplitude variation degree of each cluster comprises: Taking any cluster as the target cluster, and taking the sequence formed by all reference indirect signals in the target cluster in time order as the signal sequence of the target cluster; Taking any two adjacent reference indirect signals in the signal sequence as a reference signal group, and obtaining the amplitude variation of each reference signal group according to the difference between the amplitudes of the two reference indirect signals in each reference signal group; The overall level of amplitude variation of all reference signal groups is analyzed to obtain the degree of signal amplitude variation of the target cluster.

7. The low-power positioning method for an underwater robot according to claim 1, characterized in that: The step of obtaining the mobile state value of the underwater robot includes: The distance between the starting position and the ending position of the underwater robot is normalized to obtain a moving state value of the underwater robot.

8. The low-power positioning method for an underwater robot according to claim 1, characterized in that: The obtaining of the state evaluation value of the underwater robot at the target time comprises: The movement state value of the underwater robot and the real danger state value at the target time are integrated and normalized to obtain the state evaluation value of the underwater robot at the target time.

9. The low-power positioning method for an underwater robot according to claim 1, characterized in that: The step of obtaining the adjustment period of the underwater robot comprises: Based on the state evaluation values ​​at the corresponding moments when the survey signals of the underwater robot are received all times, an overall state evaluation value of the underwater robot within a preset time period after the current moment is obtained; The difference between the preset maximum period and the preset minimum period of the positioning signal transmitted by the underwater robot is used as the period adjustment limit value of the underwater robot; Using the overall state evaluation value, weighting the period adjustment limit value of the underwater robot to obtain the period adjustment amount of the underwater robot; The difference between the preset maximum period of the positioning signal transmitted by the underwater robot and the period adjustment amount is used as the adjustment period of the underwater robot.

10. A low-power positioning method for an underwater robot according to claim 9, characterized in that: The obtaining of the overall state evaluation value of the underwater robot within a preset time period after the current moment includes: Performing time series prediction processing on the state evaluation values ​​at the corresponding moments when all the survey signals of the underwater robot are received, to obtain a preset number of predicted state evaluation values; The overall level of all the predicted state evaluation values ​​is analyzed to obtain the overall state evaluation value of the underwater robot within a preset time period after the current moment.

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