CN114154117A

CN114154117A - SLAM method

Info

Publication number: CN114154117A
Application number: CN202111532176.8A
Authority: CN
Inventors: 任杰
Original assignee: Yuanxiang Technology Suzhou Co ltd
Current assignee: Metoak Technology Beijing Co ltd; Yuanxiang Technology Suzhou Co ltd
Priority date: 2021-06-15
Filing date: 2021-06-15
Publication date: 2022-03-08
Anticipated expiration: 2041-06-15
Also published as: CN113392370B; CN114154117B; CN113392370A

Abstract

The invention discloses a SLAM method; belongs to the field of synchronous positioning and map construction of a movable platform; the technical key points are as follows: abstracting and expressing images received by machine vision into different levels of information; the higher the information single memory space of the higher layer is, the higher the information single memory space of the lower layer is; the higher the information number of the layer, the more; the lower layers have fewer information numbers. By adopting the high-efficiency long-time large-scale SLAM method, the performance and the high efficiency of loop detection under the long-time large-scale SLAM are achieved.

Description

SLAM method

The application is a divisional application, the application number of the original application is 202110658243.4, the application date is 2021, 6 months and 15 days, and the invention name is 'an efficient long-time large-scale SLAM method and system'.

Technical Field

The invention relates to the technical field of automobile synchronous positioning and map construction, in particular to an SLAM method.

Background

SLAM, an acronym for Simultaneous localization and Mapping, which is interpreted as: synchronous positioning and map construction; the technology is a core technology (which belongs to support software in the field of intelligent transportation) for realizing autonomous navigation positioning and building an environment map for an automobile.

The existing Visual SLAM algorithm faces the main problem that a large amount of historical information needs to be stored to carry out Loop Detection (Loop Closure Detection) in a larger scale and a longer time range to reduce accumulated deviation when facing Long-term (Long-term) and large-scale (Large-scale) scenes.

For example, CN111767854A proposes a SLAM loop detection method combining scene text semantic information, which has the core steps of: for any key frame in the key frame set, calculating the cosine similarity of the total information vector and the current frame total information vector, and taking the key frame of which the similarity is greater than a certain threshold and which is not directly adjacent to the current frame as a loop candidate frame. As this approach, there is the aforementioned problem of storing information vectors for each key frame. This is very stressful for hardware storage devices.

Disclosure of Invention

The invention aims to provide an SLAM method, which solves the defects in the prior art.

A SLAM method comprising the steps of:

abstracting and expressing images received by machine vision into different levels of information;

the higher the information individual storage amount, the higher the information individual storage amount of the lower layer (i.e., X)_j，βThe storage space occupied by a single is less than X_j+1，βA single occupied storage space);

the higher the information number of the layer, the more; the lower the layer, the less the information number (i.e., Q described below)_j>Q_j+1)。

An efficient long-time large-scale SLAM method comprises the following steps:

s100, establishing an information hierarchy sequence of the key frames:

the information hierarchy sequence of the key frame is expressed as follows according to the descending order of the hierarchy level by level: level 1 information, level 2 information, level j information … … …, level k information:

s200, determining the storage capacity of each information level of the key frame:

the storage amount of the 1 st level information is Q₁The storage amount of the 2 nd level information is Q₂… … … … the storage capacity of the j level information is Q_j… … … … the k-th level information has a storage capacity of Q_k：

For Q₁～Q_kFor example, there are: q₁>Q₂>……Q_j-1>Q_j>……Q_k；

S300, the current key frame is the Yth key frame, and the information of layers 1 to k is extracted from the Yth key frame: x_1，Y、X_2，Y、……X_j，Y、……X_k，Y(ii) a And simultaneously calculating the storage importance coefficients of the information of the 1 st to k th layers extracted from the Yth key frame: z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，Y；

X_1，Y、X_2，Y、……X_j，Y、……X_k，YRespectively represent: level 1 information of the Y-th key frame, level 2 information of the Y-th key frame, … … level j information of the Y-th key frame, … … level k information of the Y-th key frame;

Z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，Yrespectively represent: a storage importance coefficient of level 1 information of a Y-th key frame, a storage importance coefficient of level 2 information of the Y-th key frame, a storage importance coefficient of a j-th level information of … … the Y-th key frame, a storage importance coefficient of a k-th level information of … … the Y-th key frame;

s400, the storage importance coefficients of the information of the 1 st to k th layers extracted from the current Y-th key frame are: z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，YAdding the importance parameter into a storage importance coefficient matrix of the current key frame level information (all the storage importance parameters of the extracted 1 st-k level information of the Y-th key frame are stored into the storage importance coefficient matrix of the current key frame level information);

S500，

extracting the information of the 1 st to k th layers from the current Y-th key frame: x_1，Y、X_2，Y、……X_j，Y、……X_k，Y，Adding the key frame level information into a current key frame level information matrix:

when 0 is present<Y≤Q_kWhen the current key frame set is selected, all the extracted 1 st-k level information of the Y key frame is stored into the current key frame set;

the above steps are expressed as follows:

X_j，Iexpressing j level information of the I key frame;

when Q is_j<Y≤Q_j-1When j represents any natural number from 2 to k;

storing all the level information from level 1 to level j-1 of the Y key frame into the current key frame set, wherein the steps are expressed by adopting the following formula:

for j-th to k-th level information of the Y-th key frame, calculating layer by layer, and determining whether to store:

for any of the j-th to k-th layers:

first, from Z_β,1,Z_β,2……Z_β,I……Z_β,Y-1Finding the minimum value, which takes Z_β,mThe information storage importance parameter of the mth key frame beta level is minimum;

secondly, according to Z_β,m、Z_β,YDetermines whether to store the beta level information X of the Y-th key frame_β,Y：

When Z is_β,m>Z_β,Y

Then Z_β,YGiven a new value such that Z_β,YNo longer participate in the ranking;

X_β,Yassigning a new value of NULL or 0, i.e. for the Yth key frameThe beta level information is not stored;

when Z is_β,m≤Z_β,Y

Then Z_β,mGiven a new value such that Z_β,mNo longer participate in the ranking;

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YStoring, namely, the storage space of the beta level information of the mth key frame is reserved to the storage space of the beta level information of the Yth key frame, namely, the storage space of the beta level information is always kept at Q_β；

When Q is₁<When Y is in the range of:

for the level 1-k information of the Y key frame, calculating layer by layer, and determining whether to store:

for any of the 1 st to k th layers,

When Z is_β,m>Z_β,Y

X_β,Ygiving a new value of NULL or 0, namely not storing the beta level information of the Yth key frame;

when Z is_β,m≤Z_β,Y

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YStoring, i.e. of the mth key frameThe storage space of the beta level information is allowed to be equal to the storage space of the beta level information of the Y key frame, namely the storage quantity of the beta level information is always kept at Q_β。

Further, "when Z" in step S500_β,m>Z_β,Y，Z_β,YNew values are assigned ", NULL or + ∞.

Further, in step S100, k is not less than 4.

The invention has the beneficial effects that:

first, the basic idea of the present application is: abstracting and expressing information received by machine vision at different semantic levels, and coding the information from the information level; the higher the semantic feature of the higher layer, the more simplified the information quantity stored, the higher the extraction frequency, the longer the time stored in the SLAM system; conversely, the lower the level of the point cloud feature, the larger the amount of data stored, the lower the frequency of extraction, and the shorter the time for storage in the SLAM system. By setting different storage and retrieval index configurations, the performance and the efficiency of freely allocating storage/retrieval and long-time large-scale SLAM loop detection are achieved.

Secondly, based on the basic concept of the application, a method for storing the SLAM key frame matrix is provided: the storage is determined by means of a double coefficient, namely: and storing the importance coefficient matrix and the current key frame level information matrix to jointly determine how the newly acquired 1 st-k level information of the Y-th key frame is stored into the current key frame level information matrix.

Drawings

The invention will be further described in detail with reference to examples of embodiments shown in the drawings to which, however, the invention is not restricted.

Fig. 1 is a sequence layout diagram of information hierarchy according to the first embodiment.

Fig. 2 is a schematic diagram of "original image-dense point cloud feature" extraction according to the first embodiment.

Detailed Description

An efficient long-time large-scale SLAM method comprises the following steps:

s100, establishing an information hierarchy sequence of the key frames:

For Q₁～Q_kFor example, there are: q₁>Q₂>……Q_j-1>Q_j>……Q_k；

s400, the storage importance coefficients of the information of the 1 st to k th layers extracted from the current Y-th key frame are: z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，YJoin to current key frame(at this time, there are 1 st to Y-1 st key frames corresponding to the current key frame) in the storage importance parameter set (i.e. the storage importance coefficient matrix added to the current key frame level information):

all storage importance parameters of the extracted 1 st-k level information of the Y-th key frame are stored into a storage importance coefficient matrix of the current key frame level information;

the above steps can be expressed as follows:

S500，

extracting the information of the 1 st to k th layers from the current Y-th key frame: x_1，Y、X_2，Y、……X_j，Y、……X_k，Y，Add to the current key frame set (i.e., to the current key frame level information matrix):

_kwhen 0 is present<When Y is less than or equal to QStoring all the extracted 1 st-k level information of the Y-th key frame into the current key frame set;

the above steps can be expressed as follows:

X_j，Iinformation of j level expressing the I key frame (the meaning of other expressions can be known from it, for example, X_k，YK-th level information expressed as the Y-th key frame).

_k _k-1When Q is<When Y is less than or equal to QAnd storing all the level information from level 1 to level k-1 of the Y-th key frame into the current key frame set, wherein the steps can be expressed as follows:

for the kth layer information of the Y-th key frame:

first, from Z_k,1,Z_k,2……Z_k,I……Z_k,Y-1Finding the minimum value, which takes Z_k,mThe information storage importance parameter of the kth level of the mth key frame is minimum;

secondly, according to Z_k,m、Z_k,YDetermines whether to store the kth level information X of the Yth key frame_k,Y：

When Z is_k,m>Z_k,Y

Then Z_k,YAssigning a new value (e.g., NULL or + ∞) (so that Z_k,YNo longer participating in the ranking);

X_k,Ygiving a new value of NULL or 0, namely not storing the kth level information of the Yth key frame;

when Z is_k,m≤Z_k,Y

Then Z_k,mGiven a new value such that Z_k,mNo longer participate in the ranking;

X_k,massigning a new value of NULL or 0, i.e. removing the kth level information of the mth key frame and adding the kth level information X of the Yth key frame_k,YStoring, namely, the storage space of the k-level information of the mth key frame is saved to the storage space of the k-level information of the Yth key frame (namely, the storage amount of the k-level information is always kept at Q_k)。

……

_j _j-1When Q is<When Y is less than or equal to QAnd storing all the level information from level 1 to level j-1 of the Y-th key frame into the current key frame set, wherein the steps can be expressed as follows:

for the j-th to k-th level (it should be noted that j in this application represents any natural number between [1, k ] rather than k-1, i.e. the order of j, k in english does not represent the distance between the two) information of the Y-th key frame, the calculation is performed layer by layer to determine whether to store:

for the jth level information of the yth key frame:

first, from Z_j,1,Z_j,2……Z_j,I……Z_j,Y-1Finding the minimum value, which takes Z_j,mThe j level information storage importance parameter of the mth key frame is minimum;

secondly, according to Z_j,m、Z_j,YDetermines whether to store the j level information X of the Y key frame_j,Y：

When Z is_j,m>Z_j,Y

Then Z_j,YAssigning a new value (e.g., NULL or + ∞) such that Z_j,YNo longer participate in the ranking;

X_j,Ygiving a new value of NULL or 0, namely not storing the j level information of the Y key frame;

when Z is_j,m≤Z_j,Y

Then Z_j,mGiven a new value such that Z_j,mNo longer participate in the ranking;

X_j,massigning a new value of NULL or 0, i.e. deleting the j level information of the mth key frame and adding the j level information X of the Yth key frame_j,YStoring, namely, the storage space of the j level information of the mth key frame is made to be equal to the storage space of the j level information of the Yth key frame (namely, the storage amount of the j level information is always kept at Q_j)。

For the j +1 th level information of the Y-th key frame:

first, from Z_j+1,1,Z_j+1,2……Z_j+1,I……Z_j+1,Y-1Finding the minimum value, which takes Z_j+1,mThe j +1 th level information storage importance parameter of the mth key frame is minimum;

secondly, according to Z_j+1,m、Z_j+1,YDetermines whether to store the j +1 th level information X of the Yth key frame_j+1,Y：

When Z is_j+1,m>Z_j+1,Y

Then Z_j+1,YAssigning a new value (e.g., NULL or + ∞) such that Z_j+1,YNo longer participate in the ranking;

X_j+1,Ygiving a new value of NULL or 0, namely not storing the j +1 level information of the Yth key frame;

when Z is_j+1,m≤Z_j+1,Y

Then Z_j+1,mGiven a new value such that Z_j+1,mNo longer participate in the ranking;

X_j+1,massigning a new value of NULL or 0, i.e. removing the j +1 level information of the mth key frame and deleting the j +1 level information X of the Yth key frame_j+1,YStoring, namely, the storage space of the j +1 level information of the mth key frame is made to be equal to the storage space of the j +1 level information of the Yth key frame (namely, the storage amount of the j +1 level information is always kept at Q_j+1)。

………

For the kth layer information of the Y-th key frame:

When Z is_k,m>Z_k,Y

when Z is_k,m≤Z_k,Y

X_k,mgiving a new value NULL or 0, i.e. removing the k level information of the mth key frame and removing the k level information X of the Yth key frame_k,YStoring, namely, the storage space of the k-level information of the mth key frame is saved to the storage space of the k-level information of the Yth key frame (namely, the storage amount of the k-level information is always kept at Q_k)。

……

₂ ₁When Q is<When Y is less than or equal to Q，

Storing all the level 1 information of the Y-th key frame into the current key frame set, wherein the steps can be expressed as follows:

|X_1，1X_1，2......X_1，I......X_1，Y-1|—>|X_1，1X_1，2......X_1，I......X_1，Y-1X_1，Y|

for the 2 nd to k th level information of the Y-th key frame, calculating layer by layer, and determining whether to store:

for the level 2 information of the Y-th key frame:

first, from Z_2,1,Z_2,2……Z_2,I……Z_2,Y-1Finding the minimum value, which takes Z_2,mTo indicate that the storage importance parameter of the mth key frame level 2 information is minimum;

secondly, according to Z_2,m、Z_2,YDetermines whether to store the 2 nd level information X of the Yth key frame_2,Y：

When Z is_2,m>Z_2,Y

Then Z_2,YAssigning a new value (e.g., NULL or + ∞) such that Z_2,YNo longer participate in the ranking;

X_2,Ygiving a new value of NULL or 0, namely not storing the 2 nd level information of the Yth key frame;

when Z is_2,m≤Z_2,Y

Then Z_2,mGiven a new value such that Z_2,mNo longer participate in the ranking;

X_2,mendowing with a newThat is, the level 2 information of the mth key frame is deleted, and the level 2 information X of the yth key frame is deleted_2,YStoring, namely, the storage space of the 2 nd level information of the mth key frame is saved to the storage space of the 2 nd level information of the Yth key frame (namely, the storage amount of the 2 nd level information is always kept at Q₂)。

For the level 3 information of the Yth key frame:

first, from Z_3,1,Z_3,2……Z_3,I……Z_3,Y-1Finding the minimum value, which takes Z_3,mTo indicate that the 3 rd level information storage importance parameter of the mth key frame is minimum;

secondly, according to Z_3,m、Z_3,YDetermines whether to store the 3 rd level information X of the Yth key frame_3,Y：

When Z is_3,m>Z_3,Y

Then Z_3,YAssigning a new value (e.g., NULL or + ∞) such that Z_3,YNo longer participate in the ranking;

X_3,Ygiving a new value of NULL or 0, namely not storing the 3 rd level information of the Yth key frame;

when Z is_3,m≤Z_3,Y

Then Z_3,mGiven a new value such that Z_3,mNo longer participate in the ranking;

X_3,massigning a new value of NULL or 0, i.e., removing the 3 rd level information of the mth key frame and adding the 3 rd level information X of the yth key frame_3,YStoring, namely, the storage space of the 3 rd level information of the mth key frame is saved to the 3 rd level information storage space of the Yth key frame (namely, the storage space of the 3 rd level information is always kept at Q₃)。

………

For the kth layer information of the Y-th key frame:

first, from Z_k,1,Z_k,2……Z_k,I……Z_k,Y-1Finding the minimum value, which takes Z_k,mTo express, i.e. the mth key frame K level informationThe information storage importance parameter is minimum;

When Z is_k,m>Z_k,Y

when Z is_k,m≤Z_k,Y

₁When Q is<At Y time：

for level 1 information of the Y-th key frame:

first, from Z_1,1,Z_1,2……Z_1,I……Z_1,Y-1Finding the minimum value, which takes Z_1,mThe 1 st level information storage importance parameter of the mth key frame is minimum;

secondly, according to Z_1,m、Z_1,YDetermines whether to store the level 1 information X of the Yth key frame_1,Y：

When Z is_1,m>Z_1,Y

Then Z_1,YAssigning a new value (e.g., NULL or + ∞) such that Z_1,YNo longer participate in the ranking;

X_1,Ygiving a new value of NULL or 0, namely not storing the level 1 information of the Yth key frame;

when Z is_1,m≤Z_1,Y

Then Z_1,mGiven a new value such that Z_1,mNo longer participate in the ranking;

X_1,massigning a new value of NULL or 0, i.e. deleting the level 1 information of the mth key frame and deleting the level 1 information X of the Yth key frame_1,YStoring, namely, the storage space of the 1 st level information of the mth key frame is saved to the 1 st level information storage space of the Yth key frame (namely, the storage amount of the 1 st level information is always kept at Q₁)。

For the level 2 information of the Y-th key frame:

When Z is_2,m>Z_2,Y

when Z is_2,m≤Z_2,Y

X_2,massigning a new value of NULL or 0, i.e., deleting the 2 nd level information of the mth key frame and deleting the 2 nd level information X of the Yth key frame_2,YStoring, namely, the storage space of the 2 nd level information of the mth key frame is saved to the storage space of the 2 nd level information of the Yth key frame (namely, the storage of the 2 nd level information)The quantity is always kept at Q₂)。

For the level 3 information of the Yth key frame:

When Z is_3,m>Z_3,Y

when Z is_3,m≤Z_3,Y

………

For the kth layer information of the Y-th key frame:

When Z is_k,m>Z_k,Y

when Z is_k,m≤Z_k,Y

An efficient long-term large-scale SLAM system, comprising: the system comprises an information level sequence establishing module, an information level memory space establishing module, a current key frame information extracting module, a current key frame information storage importance coefficient calculating module and a key frame set level information storage importance coefficient calculating and storing module; a key frame set level information calculating and storing module;

the information level sequence establishing module and the information level memory space establishing module are respectively connected with the current key frame information extracting module;

the information level sequence establishing module and the information level storage capacity establishing module are respectively connected with the current key frame information storage importance coefficient calculating module;

the current key frame information storage importance coefficient calculation module is connected with the key frame set level information storage importance coefficient calculation and storage module;

the current key frame information extraction module and the key frame set level information storage importance coefficient calculation and storage module are respectively connected with the key frame set level information calculation and storage module;

the information level sequence establishing module is used for establishing an information level sequence of a key frame set and guiding the current key frame information extracting module to extract information of a current key frame image, and is a carrier operated in the step S100;

the information level storage quantity establishing module is used for establishing different level information storage spaces of the key frame set and is a carrier operated in the step S200;

the current key frame information extraction module is used for extracting information of different levels from the current key frame image, and is a carrier operated in the step S300;

the current key frame information storage importance coefficient calculation module is used for calculating storage importance coefficients of different levels of information of the current key frame;

the key frame set level information storage importance coefficient calculation and storage module is used for storing the storage importance coefficients of different level information of the current key frame set;

the key frame set level information calculation and storage module is used for determining a storage mode (namely determining whether the key frame set level information is stored) for extracting information of different levels from the current key frame image transmitted by the current key frame information extraction module.

It should be noted that: the information level sequence establishing module and the information level storage capacity establishing module are not necessary technical features, that is, the S100 and the S200 are not necessarily set by the two modules, and a designer can directly set related parameters in the software system.

The first embodiment is as follows: as shown in fig. 1, an efficient long-term large-scale SLAM method performs hierarchical processing on information of a key frame set; the method comprises the following steps:

s100, establishing an information level sequence of the key frame set:

level 1 information, namely a characteristic word set (namely a BOW model) of a scene;

level 2 information: spatial relationship expression of spatial entities;

level 3 information: point/line/surface features;

level 4 information: dense point cloud features.

S200, establishing the storage priority of the information of the key frame set according to the information level sequence established in the step S100: the storage amount of the information level of the hierarchy is larger than that of the information level of the hierarchy, and the storage time of the information level of the hierarchy is longer than that of the information level of the hierarchy.

Specifically, S200 is to determine the storage capacity of the 1 st to 4 th information levels of the key frame:

the storage amount of the 1 st level information is Q₁The amount of storage of the 2 nd level information is Q50000₂40000, the amount of storage of the 3 rd level information is Q₃10000, the storage amount of the 4 th hierarchy information is Q₄＝700：

S300, the current key frame is the Y-th key frame, as shown in fig. 1: extracting information of layers 1-4 from the Yth key frame: x_1，Y、X_2，Y、X_3，Y、X_k，Y；

And simultaneously calculating the storage importance coefficients of the information of the 1 st to k th layers extracted from the Yth key frame: z_1，Y、Z_2，Y、Z_3，Y、Z_k，Y(ii) a The calculation principle of the storage importance coefficient can be specifically determined and adjusted by a system designer according to actual requirements and environments. For example: i am giving the machine in an indoor simulated environment a design of: the storage importance coefficient of the crossroad is positioned by 1.0, the storage importance coefficient of the T-shaped crossroad is positioned by 0.8, and the storage importance coefficient of the middle of the road is positioned by 0.5.

X_1，Y、X_2，Y、X_3，Y、X_4，YRespectively represent: level 1 information of a Y-th key frame, level 2 information of the Y-th key frame, level 3 information of the Y-th key frame, and level 4 information of the Y-th key frame;

Z_1，Y、Z_2，Y、Z_3，Y、Z_4，Yrespectively represent: storage importance coefficient of level 1 information of the Y-th key frame, storage importance coefficient of level 2 information of the Y-th key frame, storage importance coefficient of level 3 information of the Y-th key frame, storage importance coefficient of level 4 information of the Y-th key frameA coefficient of sex;

s400, the storage importance coefficient of the information of the 1 st to 4 th layers extracted from the current Y-th key frame is: z_1，Y、Z_2，Y、Z_3，Y、Z_4，YAdding the importance coefficient into a storage importance coefficient matrix of the current key frame level information:

all storage importance parameters of the extracted 1 st-4 th-level information of the Y-th key frame are stored into a storage importance coefficient matrix of the current key frame level information;

the above steps can be expressed as follows:

s500, extracting the information of the 1 st to 4 th layers from the current Y-th key frame: x_1，Y、X_2，Y、X_3，Y、X_4，Y，Adding the key frame into a current key frame level information matrix:

extracting the information of the 1 st to 4 th layers of the current Y-th key frame: x_1，Y、X_2，Y、X_3，Y、X_4，Y，Adding the key frame level information into a current key frame level information matrix:

₄when 0 is present<When Y is less than or equal to QStoring all the extracted 1 st-4 th-level information of the Y-th key frame into a current key frame set;

the above steps can be expressed as follows:

for the j-th to 4-th level information of the Y-th key frame, calculating layer by layer, and determining whether to store:

for any of the jth to 4 th layers,

When Z is_β,m>Z_β,Y

Then Z_β,YAssigning a new value (e.g., NULL or + ∞) such that Z_β,YNo longer participate in the ranking;

when Z is_β,m≤Z_β,Y

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YStoring, namely, the storage space of the beta level information of the mth key frame is saved to the storage space of the beta level information of the Yth key frame (namely, the storage space of the beta level information is always kept at Q_β)。

₁When Q is<At Y time：

For the level 1-4 information of the Y key frame, calculating layer by layer, and determining whether to store:

for any beta-th layer of the 1 st to 4 th layers,

first, from Z_β,1,Z_β,2……Z_β,I……Z_β,Y-1Finding the minimum value, which takes Z_β,mTo indicate that the user is not in a normal position,the information storage importance parameter of the mth key frame level beta is minimum;

When Z is_β,m>Z_β,Y

when Z is_β,m≤Z_β,Y

It should be noted that, according to the first embodiment: for any I key frame j layer information X_j,IThe value is not limited to be a numerical value, that is, it may be a character set, for example, as in the first embodiment: x_1，IIs the BOW model data, and may also be a data set, for example: the first embodiment is as follows: x_4，IIs a dense point cloud data set.

The above-mentioned embodiments are only for convenience of description, and are not intended to limit the present invention in any way, and those skilled in the art will understand that the technical features of the present invention can be modified or changed by other equivalent embodiments without departing from the scope of the present invention.

Claims

1. An efficient long-time large-scale SLAM method is characterized in that:

the higher the information single memory space of the higher layer is, the higher the information single memory space of the lower layer is;

the higher the information number of the layer, the more; the lower layers have fewer information numbers.

2. An efficient long-time large-scale SLAM method is characterized by comprising the following steps:

s100, establishing an information hierarchy sequence of the key frames:

For Q₁～Q_kFor example, there are: q₁>Q₂>……Q_j-1>Q_j>……Q_k；

X_1，Y、X_2，Y、……X_j，Y、……X_k，YRespectively represent: level 1 information of the Yth key frame, level 2 information of the Yth key frame_、… … j-th level information of the Y-th key frame_、… … kth level information of the Yth key frame;

Z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，Yrespectively represent: storage importance coefficient of level 1 information of the Y-th key frame and storage importance coefficient of level 2 information of the Y-th key frame_、… … storage importance coefficient of j level information of Y key frame_、… … storage importance coefficient of kth level information of the Yth key frame;

s400, the storage importance coefficients of the information of the 1 st to k th layers extracted from the current Y-th key frame are: z_1，Y、Z_2，Y、……Z_j，Y、……Z_k，YAdding the key frame level information into a storage importance coefficient matrix of the current key frame level information;

S500，

the above steps are expressed as follows:

X_j，Iexpressing j level information of the I key frame;

when Q is_j<Y≤Q_j-1When j represents any natural number from 2 to k;

for any of the j-th to k-th layers:

When Z is_β,m>Z_β,Y

when Z is_β,m≤Z_β,Y

When Q is₁<When Y is in the range of:

for any of the 1 st to k th layers,

first, from Z_β,1,Z_β,2……Z_β,I……Z_β,Y-1Finding the minimum value, which takes Z_β,mIs expressed, i.e. the mth key frameThe storage importance parameter of the beta-level information is minimum;

When Z is_β,m>Z_β,Y

when Z is_β,m≤Z_β,Y

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YStoring, namely, the storage space of the beta level information of the mth key frame is reserved to the storage space of the beta level information of the Yth key frame, namely, the storage space of the beta level information is always kept at Q_β。

3. The method of claim 2, wherein step S500 is "when Z" in the method_β,m>Z_β,Y，Z_β,YNew values are assigned ", NULL or + ∞.

4. An efficient long-term large-scale SLAM method as claimed in claim 2 or 3 wherein k is 4 ≦ k in step S100.

5. A SLAM method is characterized in that the information of a key frame set is processed hierarchically; the method comprises the following steps:

s100, establishing an information level sequence of the key frame set:

level 1 information is a characteristic word set of a scene;

level 2 information: spatial relationship expression of spatial entities;

level 3 information: point/line/surface features;

level 4 information: dense point cloud features;

s200, establishing the storage priority of the information of the key frame set according to the information level sequence established in the step S100: the storage capacity of the information level with high hierarchy is larger than that of the information level with low hierarchy, and the storage time of the information level with high hierarchy is larger than that of the information level with low hierarchy;

s300, the current key frame is the Yth key frame, and the information of layers 1-4 is extracted from the Yth key frame: x_1，Y、X_2，Y、X_3，Y、X_k，Y；

And simultaneously calculating the storage importance coefficients of the information of the 1 st to k th layers extracted from the Yth key frame: z_1，Y、Z_2，Y、Z_3，Y、Z_k，Y(ii) a Storing the calculation principle of the importance coefficient;

Z_1，Y、Z_2，Y、Z_3，Y、Z_4，Yrespectively represent: the storage importance coefficient of the 1 st level information of the Y-th key frame, the storage importance coefficient of the 2 nd level information of the Y-th key frame, the storage importance coefficient of the 3 rd level information of the Y-th key frame and the storage importance coefficient of the 4 th level information of the Y-th key frame;

the above steps are expressed as follows:

when 0 is present<Y≤Q₄When the current key frame set is selected, all the level 1-4 information extracted from the Y key frame is stored into the current key frame set;

the above steps are expressed as follows:

when Q is_j<Y≤Q_j-1When the current key frame set is used, all the level information 1-j-1 of the Y key frame is stored into the current key frame set, and the steps are expressed by adopting the following formula:

for any of the jth to 4 th layers,

secondly, according toZ_β,m、Z_β,YDetermines whether to store the beta level information X of the Y-th key frame_β,Y：

When Z is_β,m>Z_β,Y

Then Z_β,YAssigning a new value NULL or + ∞sothat Z_β,YNo longer participate in the ranking;

when Z is_β,m≤Z_β,Y

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YStoring, namely, a storage space of the beta level information of the mth key frame is made to be equal to a storage space of the beta level information of the Yth key frame;

when Q is₁<When Y is in the range of:

for any beta-th layer of the 1 st to 4 th layers,

When Z is_β,m>Z_β,Y

when Z is_β,m≤Z_β,Y

X_β,massigning a new value of NULL or 0, i.e., deleting the beta level information of the mth key frame and adding the beta level information X of the Yth key frame_β,YAnd storing, namely, the storage space of the beta level information of the mth key frame is made to be the beta level information storage space of the Yth key frame.

6. The SLAM method as claimed in claim 5 wherein in step S300, the storage importance coefficients for intersections are located at 1.0, the storage importance coefficients for intersections are located at 0.8, and the storage importance coefficients for the middle of the road are located at 0.5.