Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a laser radar SLAM degradation detection method and system based on pose constraint.
According to one aspect of the present invention, there is provided a laser radar SLAM degradation detection method based on pose constraint, including:
collecting continuous frame point clouds through a laser radar sensor;
analyzing the continuous frame point cloud to obtain a point cloud constraint relation of robot pose disturbance rejection robustness;
and carrying out robot pose constraint disturbance recognition according to the point cloud constraint relation to obtain a degradation direction.
Preferably, the analyzing the continuous frame point cloud to obtain a point cloud constraint relationship of robot pose disturbance rejection robustness includes:
approximating the local surface of the continuous frame point cloud as a plane, each measurement point satisfying the following relation:
wherein,,
is the unit vector of the laser beam in the radar coordinate system for indicating the beam direction,/or%>
Corresponding to the beam length, i.e {1,2, …, m } is the index of the laser spot beam, +.>
Is an approximately planar normal vector, p
i,0 Is a point on the approximate plane, +.>
The position and attitude of the robot are described separately;
will be
Denoted as d
i The point cloud constraint relation for obtaining the robot pose disturbance rejection robustness is as follows:
preferably, the performing robot pose constraint disturbance recognition according to the point cloud constraint relationship includes:
in the point cloud registration process, the position and posture (R, t) of the robot change less, and the change of (R, t) can be regarded as disturbance;
measuring distance ρ by calculating laser i And judging whether the laser radar SLAM has scene degradation or not according to the sensitivity degree of the (R, t) disturbance.
Preferably, if the pose of the robot is disturbed and the laser measurement distance is changed greatly, the pose constraint of the robot is described to be stronger currently; otherwise, if the pose of the robot is disturbed and the laser measurement distance is not changed greatly, the robot is extremely weak in constraint and the system is in a degradation environment.
Preferably, the obtaining the degradation direction includes:
based on the assumption of small angle transformation in robot pose, R.apprxeq.I+ [ theta ] is used] × Linearizing the derivative problem:
based on the hidden function theorem, an equation is established:
derivation of cocoa the product can be obtained by the method,
according to the formula obtained by the hidden function theorem, an F matrix and a T matrix are constructed, wherein the sensitivity of laser constraint to translation parameters and the sensitivity of laser constraint to rotation parameters are respectively represented:
performing eigenvalue decomposition on the F matrix and the T matrix to obtain a group of eigenvectors,
the feature vector corresponding to the minimum feature value is the current degradation direction: the minimum eigenvalue of the F matrix is used for judging the degradation direction of the translation quantity; the minimum eigenvalue of the T matrix is used to determine the degradation direction of rotation.
Preferably, the projection of the matrix on any feature vector is the expansion and contraction of the feature vector, the expansion and contraction proportion is a feature value, the feature value reflects the proportion of the projection of the matrix in the direction of the feature vector, and the smaller the feature value is, the smaller the constraint of the matrix in the direction of the feature vector is, the smaller the constraint is, and the degradation is easy to occur in the direction.
Preferably, if lambda min Less than the set threshold, representing degradation of the current scene; at the same time, a minimum eigenvalue lambda min The corresponding feature vector is the current degradation direction.
According to a second aspect of the present invention, there is provided a laser radar SLAM degradation detection system based on pose constraint, comprising:
the data module is used for collecting continuous frame point clouds through a laser radar sensor;
the constraint relation module analyzes the continuous frame point clouds and obtains a point cloud constraint relation of robot pose disturbance rejection robustness;
and the disturbance recognition module is used for carrying out robot pose constraint disturbance recognition according to the point cloud constraint relation.
According to a third aspect of the present invention, there is provided a terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor being operable, when executing the program, to perform the pose constraint based lidar SLAM degradation detection method or to run the pose constraint based lidar SLAM degradation detection system described above.
According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, is operative to perform the above-described pose constraint-based laser radar SLAM degradation detection method, or to run the above-described pose constraint-based laser radar SLAM degradation detection system.
Compared with the prior art, the invention has the following beneficial effects:
the method can solve the problem that the laser radar SLAM is difficult to detect when losing efficacy in a degradation scene, provides early warning for the stable operation of the laser SLAM, can realize higher detection accuracy, and is beneficial to practical application.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
First, terms (SLAM and degraded scene) involved in the present invention are explained. SLAM: and (3) synchronously mapping and positioning algorithms, and establishing a map of the environment scene in which the sensor is positioned in the motion process by utilizing information provided by the sensor, and simultaneously determining the corresponding position of the sensor in the map. The SLAM technology is widely applied to environment modeling and autonomous positioning navigation tasks of robots. The laser radar SLAM is a map which draws a laser scanning scene according to the point cloud information acquired by the laser radar sensor, and determines the position of the laser radar sensor in the map. Degradation scenario: the laser radar uses fewer structural textures in the scene, so that the sensor cannot provide enough constraint when the data provided in the scene faces to the optimization problem of the system, and the optimization object falls into a local optimal solution to cause the system to fail. The degradation scene of the laser radar comprises tunnels, galleries, outdoor open parking lots, highways and the like.
The invention provides an embodiment, a laser radar SLAM degradation detection method based on pose constraint, which is shown in fig. 1 and comprises the following steps:
s100, collecting continuous frame point clouds through a laser radar sensor;
s200, analyzing the continuous frame point clouds of the S200 to obtain a point cloud constraint relation of the robot pose disturbance rejection robustness;
s300, carrying out robot pose constraint disturbance recognition according to the point cloud constraint relation of S200, and obtaining the degradation direction.
The embodiment solves the problem that the laser radar SLAM is difficult to detect in failure under a degradation scene, provides early warning for the stable operation of the laser radar SLAM, can realize higher detection accuracy, and is beneficial to practical application.
In a preferred embodiment of the present invention, S100 is implemented, where a laser radar sensor collects a continuous frame point cloud, specifically, a robot carries a laser radar, and the laser radar emits laser light with a specific wavelength by means of pulse, frequency modulation, amplitude modulation, and the like, and after the laser radar irradiates an object, the laser light is reflected, and the laser light reflected after the emission is received, so as to obtain original point cloud data. Each frame includes a cloud of points, including the point clouds emitted by the m laser points. Wherein the reflection of each laser light on the object corresponds to a measurement point.
In a preferred embodiment of the present invention, S200 is implemented, that is, for laser radar positioning, pose constraints of each measurement point of the laser radar on the robot are obtained, see fig. 2, and the specific procedure is as follows:
approximating the local surface of the point cloud as a plane, then for each measurement point:
wherein the method comprises the steps of
Is the unit vector of the laser beam in the radar coordinate system for indicating the beam direction,/or%>
Corresponding to the beam length, i.e {1,2, …, m } is the index of the laser spot beam, +.>
Is an approximately planar normal vector, p
i,0 Is a point on the approximate plane, +.>
The position and pose of the robot are described separately, see fig. 3.
Will be
Denoted as d
i The following steps are:
and taking the model as a point cloud constraint relation of robot pose disturbance rejection robustness. The constraint relation describes the constraint relation between the pose of the robot and the laser point, and provides an accurate model foundation for further detecting whether the laser point measurement is degraded or not.
In a preferred implementation of the present invention, S300 is implemented, where in point cloud registration (that is, as the robot moves, the lidar continuously obtains two frames of point cloud data, and the point cloud registration needs to find a point-to-point matching relationship between the two frames of point clouds), the transformation matrices corresponding to the two registrations are not different greatly, so that (R, t) is smaller. (R, t) can be regarded as a disturbance describing the locatable capability of the system, converted into a laser measurement distance ρ i Sensitization to (R, t)Degree of feel. If the pose of the robot is slightly disturbed and the laser measurement distance is changed greatly, the pose constraint of the robot is strong. Otherwise, if the pose of the robot is disturbed, but the laser measurement distance is not changed greatly, the robot is extremely weak in constraint, and the system is in a degradation environment.
In another preferred embodiment, referring to fig. 2, the preferred process of S300 is as follows:
s301: solving the laser measurement distance ρ i For the partial derivatives of (R, t), R.apprxeq.I+ [ theta ] is used based on the assumption of a small angle transformation] × Linearizing the derivative problem:
s302: based on the hidden function theorem, an equation is established as follows:
combining S301 derivation, we can obtain:
step S303: according to the formula obtained in the step S302, an F matrix and a T matrix are constructed, wherein the sensitivity of the laser constraint to the translation parameter and the sensitivity of the laser constraint to the rotation parameter are respectively represented:
step S304: and (3) carrying out eigenvalue decomposition according to the formula obtained in the step S303 to obtain corresponding eigenvectors.
Step S305: the feature vector corresponding to the minimum feature value is the current degradation direction: the minimum eigenvalue of the F matrix is used for judging the degradation direction of the translation quantity; the minimum eigenvalue of the T matrix is used to determine the degradation direction of rotation.
The projection of any one of the eigenvectors on the coordinate system (matrix) is only the expansion and contraction of the fixed, and the expansion and contraction proportion is the magnitude of the eigenvalue, so that the eigenvalue can reflect the proportion of the vector direction on the matrix, and the smaller the eigenvalue, the smaller the constraint of the matrix on the eigenvector direction is. The constraint is small, indicating that degradation is likely to occur in this direction, and therefore the minimum eigenvalue λ min The locatability of the current location may be described.
Further, if lambda min Less than the set threshold, representing degradation of the current scene. At the same time, a minimum eigenvalue lambda min The corresponding feature vector is the current degradation direction.
Based on the same technical conception, in other embodiments of the present invention, a laser radar SLAM degradation detection system based on pose constraint is provided, which includes a data module, a constraint relation module, and a disturbance recognition module. The data module acquires continuous frame point clouds through a laser radar sensor; the constraint relation module analyzes the continuous frame point clouds to obtain a point cloud constraint relation of robot pose disturbance rejection robustness; and the disturbance recognition module performs robot pose constraint disturbance recognition according to the point cloud constraint relation.
Based on the same technical concept, in other embodiments of the present invention, a terminal is provided, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the program and is used to perform the above method or to run the above system.
Optionally, a memory for storing a program; memory, which may include volatile memory (english) such as random-access memory (RAM), such as static random-access memory (SRAM), double data rate synchronous dynamic random-access memory (Double Data Rate Synchronous Dynamic Random Access Memory, DDR SDRAM), and the like; the memory may also include a non-volatile memory (English) such as a flash memory (English). The memory is used to store computer programs (e.g., application programs, functional modules, etc. that implement the methods described above), computer instructions, etc., which may be stored in one or more memories in a partitioned manner. And the above-described computer programs, computer instructions, data, etc. may be invoked by a processor.
The computer programs, computer instructions, etc. described above may be stored in one or more memories in partitions. And the above-described computer programs, computer instructions, data, etc. may be invoked by a processor.
A processor for executing the computer program stored in the memory to implement the steps in the method according to the above embodiment. Reference may be made in particular to the description of the embodiments of the method described above.
The processor and the memory may be separate structures or may be integrated structures that are integrated together. When the processor and the memory are separate structures, the memory and the processor may be connected by a bus coupling.
Based on the same technical idea, in other embodiments of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, which program, when being executed by a processor, is operative to perform the method described above, or to run the system described above.
Among them, computer-readable media include computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. In addition, the ASIC may reside in a user device. The processor and the storage medium may reside as discrete components in a communication device.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the invention. The above-described preferred features may be used in any combination without collision.