KR20120059428A - Apparatus and Method for controlling a mobile robot on the basis of past map data - Google Patents

Abstract

PURPOSE: A mobile robot control apparatus based on past map data and a method thereof are provided to improve cleaning efficiency and reduce cleaning time by utilizing the past map data for cleaning processes. CONSTITUTION: An image signal processor(120) processes an image signal by acquiring an image of a target region. A sensor part(130) receives driving path information of a mobile robot. A map generation part(140) creates a map of the target region. A driving part(160) operates a wheel part(170). A storage part(150) stores predetermined information and information acquired while cleaning. A location estimation part(111) estimates a position. A controller(110) outputs a wheel operation control signal.

Description

Apparatus and Method for controlling a mobile robot on the basis of past map data}

The present invention relates to a control apparatus and a method of a mobile robot based on past map data, and more particularly, to a control device of a past map data-based mobile robot that efficiently cleans an area to be cleaned using past map data in an autonomous robot. And to a method.

Recently, according to the development of robot technology, a mobile robot that sets and moves itself is used. Representative examples of the mobile robot include a cleaning robot for cleaning the inside of a house or building, a guide robot for guiding a location, and the like. In particular, the cleaning robot is equipped with various sensors and traveling means while cleaning the indoor floor using a vacuum cleaning unit provided therein, a number of actual products are currently used.

In order for these mobile robots to effectively locate and move in space, it is required to generate a map of the moving space and to recognize their position in space. It is called Simultaneous Localization And Mapping (SLAM) that a mobile robot recognizes its position and forms a map with respect to the surrounding space.

Among the SLAM techniques, image-based SLAM generates a map of the surrounding environment using the visual feature points extracted from the image and estimates the robot's pose. In general, a mobile robot travels in dead reckoning using an encoder provided in a gyroscope and a driving motor, and analyzes an image and generates a map using a camera installed on the top. In this case, when an error caused by driving information from the gyroscope and the encoder occurs, the accumulated error is corrected by using image information obtained from the camera.

The above-mentioned conventional autonomous mobile robot is re-creating the map information from the beginning every time cleaning is started to establish a location estimation and cleaning path plan, and there is almost no change in the internal structure in the area of past cleaning. In addition, since the map information is rewritten from the beginning, location estimation and cleaning path planning are made, which takes a lot of time when cleaning.

SUMMARY OF THE INVENTION An object of the present invention is to use the map data created in the past to solve the above problems at the time of present cleaning, whereby the mobile robot can effectively divide the cleaning area at the time of cleaning and perform cleaning in a short time efficiently. An apparatus and method for controlling a map data-based mobile robot are provided.

The control method of the past map data-based mobile robot according to the embodiments of the present invention, if the mobile robot starts cleaning according to the cleaning start command to determine the position of the starting point of the previous cleaning; Dividing the cleaning target area into a plurality of sub-areas by using the height value and the initial height value of each grid of the two-dimensional grid map having the height information and the obstacle information created as the mobile robot moves; And setting a highest cleaning level by allocating a high cleaning priority to an area having a predetermined reference size or less among the divided sub-areas, and selecting a next cleaning area in consideration of a moving path. It includes;

The determining of the position of the starting point may include extracting a feature point from an image acquired from an image sensor; Extracting a feature point candidate group through matching between a previously prepared feature point map and the extracted feature point; And searching for the starting point in the feature point candidate group by repeatedly performing the feature point extracting step and the candidate group extracting step according to a preset distance movement.

In the determining of the position of the starting point, when the starting point is found, the cleaning target area may be divided into a plurality of sub-regions using the pre-written feature point map.

The dividing into a plurality of sub-regions may include: extracting phase information from the two-dimensional grid map, and extracting at least one of an endpoint, a junction, and a connection line from the extracted phase information; And calculating distance information to the obstacle in proximity to the connection line, and acquiring visit information using the distance information.

In the acquiring of the visit information, when the minimum distance is less than or equal to the preset visit distance from the center point of the area where the size of the histogram for the distance information decreases and becomes larger, the corresponding area may be set as the visit area.

The dividing into a plurality of sub-areas may include partitioning a room area by combining link information based on the set visited area, extracting link information included only in the partitioned room area, and calculating coordinate values of a grid occupied by the link. It is possible to determine the cleaning direction of the mobile robot by obtaining the coordinates of the grid.

The control device for a mobile robot based on the past map data according to the exemplary embodiments of the present invention, when the mobile robot starts cleaning according to a cleaning start command, grasps the position of a starting point at a previous cleaning, and is created as the mobile robot moves. An image signal processor for dividing the cleaning target region into a plurality of sub-regions by using height values and initial height values of each grid of the two-dimensional grid map having height information and obstacle information; And a controller for setting a cleaning priority path by assigning a high cleaning priority to an area having a predetermined reference size or less among the divided sub-areas, and selecting a next cleaning area in consideration of a moving route. It includes;

The image signal processing unit may include a feature point extracting unit extracting feature points from an image acquired from an image sensor; And a landmark matching unit which extracts a feature point candidate group through matching between the previously prepared feature point map and the extracted feature point, and finds the starting point in the feature point candidate group.

The controller extracts phase information from the two-dimensional grid map, extracts at least one of an end point, a junction, and a connecting line, calculates distance information to the obstacle adjacent to the connecting line, and obtains the visit information. It is possible to include.

The location estimator divides a room area by combining link information based on the set visited area, extracts link information included only in the partitioned room area, obtains a coordinate value of a grid occupied by the link, and coordinates of the grid. It is possible to determine the cleaning direction of the mobile robot using the value.

An apparatus and method for controlling a mobile robot based on past map data according to an embodiment of the present invention divides an entire area into one or more sub-areas by combining a plurality of maps obtained from past driving results in an indoor self-driving coverage robot. By analyzing the overall structure and size of each area, not only can the cleaning efficiency be improved, but the cleaning time can be reduced.

In addition, the apparatus and method for controlling a mobile robot based on the past map data according to an embodiment of the present invention is an image acquisition means such as a camera installed in the upward direction when the artificial robot movement between different autonomous driving occurs It is possible to automatically recognize whether or not the mobile robot moves by using the accepted ceiling pattern.

In addition, the apparatus and method for controlling a mobile robot based on past map data according to an embodiment of the present invention provides a route plan for fast and efficient cleaning when given the overall structure and distribution of expected obstacles for a specific sub-area on a two-dimensional map. Can be established.

1 is a block diagram of an apparatus for controlling a mobile robot using past map data according to an embodiment of the present invention,
2 is a flowchart of a method for controlling a mobile robot based on past map data according to another embodiment of the present invention;
3 is a conceptual diagram for estimating the principle of the highest obstacle height using visual feature points,
4 to 6 is a conceptual diagram for establishing a coverage strategy of the cleaning target area,
7 is a conceptual diagram for map correction through vertical orientation alignment in two-dimensional space,
8 (A) and (B) each shows the change of the height map according to the position change of the robot when T = 0 and T = n,
FIG. 9 (A) shows a two-dimensional grid map finally obtained by merging a height map and a grid map together with phase information obtained using the same. FIG. 9 (B) shows a map shown in FIG. 9 (A). The cleaning area is divided and shown around each visit.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form embodiments of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

Embodiments of the invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

Throughout the specification, when a part is "connected" with another part, this includes not only a case where the part is directly connected, but also a case where the part is electrically connected with another element in between. In addition, when a part includes a certain component, this means that it may further include other components, without excluding other components, unless specifically stated otherwise.

In addition, the term module described herein refers to a unit for processing a specific function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention, and are not intended to limit the scope of the invention.

In the conventional autonomous robot cleaner, the map information is re-created from the beginning every time the cleaning is started, and the location estimation and cleaning path plan are established. It is meaningful in that it allows freedom of autonomous driving.

However, in reality, the robot cleaner is installed at a specific location and routinely cleans the same area, and considering that the movement of the robot cleaner and the docking station is infrequent, a large part of the information obtained from the driving of the previous cleaner is cleaned next time. It can be seen that it does not change even in the running of the city. In particular, by 'learning' and memorizing the size and structure of the area to be cleaned, a more intelligent robot cleaner capable of planning a more efficient cleaning path in the next cleaning can be implemented.

The present invention proposes the following new algorithm to implement an intelligent coverage robot that learns the cleaning target area as described above and efficiently performs autonomous driving at the next cleaning.

First, in case of artificial robot movement between different autonomous driving, we propose an algorithm that automatically recognizes whether or not the cleaning robot is moved by using the ceiling pattern received by image acquisition means such as a camera installed upward on the robot. .

Second, we propose an algorithm that divides the whole area into one or more sub-areas by analyzing a plurality of maps obtained from past driving in the indoor self-driving coverage robot and analyzes the overall structure and size of each sub-area.

Third, we propose an algorithm for establishing a route plan for fast and efficient cleaning when given the overall structure and distribution of expected obstacles for a specific sub-area on a two-dimensional map.

1 is a block diagram of a device for controlling a past map data-based mobile robot for dividing a cleaning target area based on past cleaning area information according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the cleaning area dividing apparatus 100 of the mobile robot may include an image signal processor 120 for acquiring an image of a target area and processing an image signal, and a sensor unit configured to receive driving path information of the mobile robot ( 130, a map generation unit 140 for creating a map of the target area based on the image signal and the surrounding information, a drive unit 160 for driving the wheel unit 170 in accordance with a control signal, and acquired at the time of cleaning. A storage unit 150 for storing information and preset information, and a position estimator 111 for estimating a position using the acquired and stored information, and a controller 110 for outputting a wheel driving control signal. do.

The image signal processor 120 may include an image sensor 121 for acquiring an image of a region to be cleaned, a feature point extractor 122 for extracting feature points from the acquired image, a landmark of the acquired image, and a landmark on a map. And a matching landmark matching unit 123.

The image signal processor 120 is an apparatus for acquiring an image of a surrounding environment in which a mobile robot is located, and includes an image sensor 121 capable of acquiring image information. The image sensor may be a charge coupled device (CCD) or a CMOS ( Complementary Metal Oxide Semiconductor) and the like can be implemented with an image sensor or a camera. In the present exemplary embodiment, the image sensor 121 is disposed to face upward to acquire a ceiling image. Preferably, the image sensor 121 includes a wide angle lens such as a fisheye lens. Can be obtained.

The sensor unit 130 includes a first sensor 131, a second sensor 132, and a third sensor 133, wherein the first, second, and third sensors include a collision sensor (bumper sensor) and an IR sensor. , Encoder, etc.

2 is a flowchart of a method for preparing a map of a mobile robot using historical map data according to another embodiment of the present invention, FIG. 3 is a conceptual diagram of a principle of estimating a maximum height of obstacles using visual feature points, and FIGS. 4 to 6 7 is a conceptual diagram for establishing a coverage strategy of the area to be cleaned, and FIG. 7 is a conceptual diagram of map correction through vertical orientation alignment of two-dimensional space, and each of FIGS. 8 (A) and (B) is T = 0 and T = n Is a change of the height map according to the position change of the robot, and FIG. 9 (A) shows a two-dimensional grid map finally obtained by merging the height map and the grid map and the phase information obtained using the same. FIG. 9 (B) shows the cleaning area divided around each visit in the map shown in FIG. 9 (A).

Hereinafter, a method of controlling a mobile robot based on past map data according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 9B.

In the embodiment of the present invention, first, the determination of the movement of the mobile robot, the analysis of the generated map information, and the coverage path planning of the area to be cleaned are described.In the analysis step of the generated map information, the principles, map implementation, and map analysis are described. I will explain in detail. In the embodiment of the present invention, a robot cleaner is used as an example of the mobile robot (autonomous driving robot) 10, but the present invention is also applicable to other types of autonomous robots that can be moved.

1) Initial location

The controller 110 determines whether the mobile robot 10 is in a moving state by using the upward camera 121. To this end, the robot cleaner includes edges, lines, corner points, brightness and blobs on the image acquired by the image sensor 121 capable of acquiring an image such as a camera installed upward. The ceiling pattern is stored by extracting feature values based on lighting characteristics such as blobs).

 The determination goal is to determine whether the position of the robot cleaner at the current cleaning is at the same starting point as the previous cleaning. The judgment point is just before the robot cleaner starts autonomous driving.

Referring to Figures 1 and 2, the initial positioning process in more detail as follows.

When a cleaning start command is input by a user or a reservation function, the mobile robot starts cleaning from the location where the mobile robot is located.

However, according to the present embodiment, when the mobile robot 10 receives a cleaning command, the feature point extractor 122 receives edges, lines, and lines from an image acquired by the image sensor 121 before or simultaneously with cleaning. Extract feature points such as corner points, brightness and blobs. The landmark matching unit 123 extracts the candidate feature point group by attempting matching with the previously registered feature point map generated by the previous cleaning and the extracted new feature point.

The mobile robot 10 repeats the feature point extraction process and the candidate group extraction process by attempting to move within a predetermined region, gradually deleting non-matching feature points from the extracted candidate feature point groups, and finally remaining candidate feature points. By using triangulation (triangulartion) to extract the planar position information (x, y coordinate) of the mobile robot 10 and the moving direction information (angle, theta) of the mobile robot.

2) Map Information Analysis

The gist of this step is that the landmark matching unit 123 uses the landmark of the ceiling image. Information input to the mapping device 100 is information obtained by a grid occupancy map (GM), a bumper or a front sensor.

- principle

If the mobile robot 10 can observe point A in real space, point B on the grid occupancy map is an obstacle, not a wall. Therefore, all positions between the camera position and the visual feature point of the mobile robot should be empty.

-Map implementation

Create a two-dimensional map with height information for a specific location so that the grid occupied map has not only information about the presence or absence of obstacles for a particular two-dimensional location, but also information about the height. For example, a 10cm by 10cm grid can create a two-dimensional map containing 100 by 100 height information, covering 10m by 10m. Each grid has a constant height value. It is preferable to make the initial value of height large enough.

Each time a visual feature point is observed, the height of the point on the two-dimensional map (2HM) containing the visual feature point and all height information connecting the camera position is calculated and the current position value of the 2HM is updated to the minimum of the two. . Finally, the 2HM will have a maximum possible height value for each two-dimensional position.

In general, when using a monocular camera, the height information also has a very high error probability in the estimation step where the uncertainty of each visual feature point is very large. Therefore, according to the present embodiment, when the uncertainty of the visual feature point is very large, the height estimation step does not update the height information. When the estimation is repeated and the length of the long axis of the uncertainty ellipse of the landmark becomes smaller than or equal to the predetermined size, the height information is obtained. Update it.

In addition, in this embodiment, since the trace of the straight line connecting the feature point and the mobile robot is used, when the number of feature points used is very small, the height map tends to be very messy. Estimate one height map.

Hereinafter, the height map estimation process will be described in more detail with reference to FIG. 8.

The landmark matching unit 123 selects and stores a feature point having high reliability among the candidate feature point group. The reliability may be determined to be high when the long axis of the uncertain ellipse is smaller than the predetermined reference long axis or the matching score for the visual feature point is high, in which case the ID, time-stamp, And the acquired image is stored.

When there is a highly reliable feature point candidate obtained at the previous point in time, the relative position is acquired by using the relationship with the feature point at the present point in time. Here, the "relationship with the feature point" means the position of each feature point on the image since the position of the camera can be roughly determined through triangulation if the same feature points can be known from two consecutive images.

Stereo image matching is performed by acquiring three-dimensional position information for each point by using the relative position information obtained from the previous point in time using the pre-stored image and the latest image. That is, when the position of the robot is known by using the wheel (when the position of the camera is known), if the corresponding characteristic point can be found in two consecutive images, the position coordinates of the characteristic point (x, y, z) Can be obtained.

The height map update is performed by updating the height map with the height information obtained above according to the Bayesian rule.

-Map analysis

If the height value of each grating is smaller than the initial value, this position is an obstacle, and if the height value of each grating is the initial value, this position is a wall. Based on the result of analyzing the map as described above, the map is divided into sub-regions using only the grid displayed by the wall excluding the obstacle region, and the approximate structure of the cleaning target region is estimated. That is, the structure of the area to be cleaned is classified into a door, a hallway cleaning area, and the like.

As described in detail below, in the map analysis process, the dominant orientation is extracted, the entire area to be cleaned is estimated as a rectangle, and the rotation is corrected through rotation.

The map shown in FIG. 9 (A) shows a two-dimensional grid map finally obtained by merging a height map and a grid map together with phase information obtained using the map. The black area is the area where there is an obstacle or is considered a wall, and the blue area is the space where the robot can drive. The white point is the representative center point of the river area, and the red line is the road connecting the white point with the constant distance from the obstacle.

In an embodiment of the present invention, the following process is performed to divide the area to be cleaned.

As described above, the two-dimensional grid map is generated by merging the grid map and the height map, and the phase information is extracted using the image thinning process or the Voronoi technique, and the end point (Fig. 9 (A ) And (B) as small white circles), junction (shown as large white circles in FIGS. 9 (A) and (B)) and connecting lines (shown as pink lines in FIGS. 9 (A) and (B)). Extract the Then, the distance to the obstacle closest to the direction perpendicular to the connecting line is displayed as a histogram, and door information is acquired using the histogram.

Hereinafter, a process of obtaining door information using the histogram will be described in more detail.

First, if the histogram indicating the magnitude of the distance is rapidly smaller and then larger again, if the minimum distance is less than or equal to the preset width, visit information is acquired using the histogram. .

The room is partitioned using the door information acquired in the above process, and the room is partitioned by combining link information based on the point defined as the visit. The compartment is indicated by a thin red circle in FIG. 9 (B).

In Fig. 9B, the area A and the area B can be merged as an exception to the case of partitioning into the room.

The cleaning direction is determined using the acquired phase information, and a specific process of the cleaning direction is performed as follows.

The link information included in each room area is extracted. In this case, the link connecting the room is ignored.

Since the extracted link information may be represented by a combination of cells on a map, a center of mass is obtained from the two-dimensional map, and coordinate values of each partitioned room are determined by a center of mass. Check in which direction it is spread. It is the same as the process of calculating the slope of a straight line using a general line regression method (ransack, least square, pac, etc.).

The mobile robot 10 uses the inclination direction obtained above as the main cleaning direction. Referring to FIG. 9 (B), in more detail, in order to determine a main direction such as in an ellipse area whose center is represented by A, B, or C, visit information is first obtained and the remaining space minus this portion is extracted. These extracted spaces may be rooms or hallways. The reference to the center of mass described above is presented as a way to find the center of a room or corridor. For example, assume that blue is 100 in each area and 0 is black in each area, and centers on the image of mass to find the approximate center point.

3) Coverage Path Planning

After cleaning the divided sub-regions first, the priority is given to cleaning the other sub-regions, the sub-regions which can be cleaned quickly and effectively are assigned the weights in order, and the cleaning plan is maximized in each sub-region. Upright to perform the cleaning efficiently.

Here, although the present invention has been applied and implemented as a robot cleaner as an example that can be implemented as a mobile robot, it can be applied to other types of mobile robots, and such an embodiment does not limit the present invention to a robot cleaner.

The driving unit 160 receives the driving control signal from the control unit 110 and controls the wheel unit 170 having the left wheel and the right wheel attached to the bottom of the main body so that the mobile robot proceeds, rotates or stops in the direction according to the control signal. Drive the wheels.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention. In addition, claims that do not have an explicit citation in the claims may be combined to form an embodiment or included in a new claim by amendment after the application.

100: mapping device 110: control unit
111: position estimation unit 120: image signal processing unit
121: image sensor 122: feature point extraction unit
123: landmark matching unit 130: sensor unit
131, 132, 133: first, second, third sensor 140: map generator
150: storage unit 160: drive unit
170: wheel part

Claims (10)

When the mobile robot starts cleaning according to the cleaning start command, determining a position of a start point of the previous cleaning;
Dividing the cleaning target area into a plurality of sub-areas by using the height value and the initial height value of each grid of the two-dimensional grid map having the height information and the obstacle information created as the mobile robot moves; And
Establishing a cleaning coverage path plan by allocating a high cleaning priority to an area having a predetermined reference size or less among the divided sub-areas, and selecting a next cleaning area in consideration of a moving path;
Mobile robot control method based on the past map data comprising a. The method of claim 1,
Determining the position of the starting point,
Extracting feature points from an image obtained from an image sensor;
Extracting a feature point candidate group through matching between a previously prepared feature point map and the extracted feature point; And
And repeating the feature point extraction step and the candidate group extraction step according to a predetermined distance movement to find the starting point in the feature point candidate group. The method of claim 2,
In the determining of the location of the starting point, when the starting point is found, the moving robot control method based on past map data is divided into a plurality of sub-areas using the pre-written feature point map. . The method of claim 1,
The dividing into the plurality of sub areas may include:
Extracting phase information from the two-dimensional grid map and extracting at least one of an endpoint, a junction and a connection line from the extracted phase information; And
And calculating distance information to the obstacle in proximity to the connection line and acquiring visit information using the distance information. The method of claim 4, wherein
The acquiring of the visit information may include setting the corresponding area as a visited area when a minimum distance from a center point of the area where the histogram with respect to the distance information becomes smaller and larger becomes less than or equal to a preset visited distance. Mobile robot control method based on map data. The method of claim 5,
The dividing into a plurality of sub-areas may include partitioning a room area by combining link information based on the set visited area, extracting link information included only in the partitioned room area, and calculating coordinate values of a grid occupied by the link. And determining the cleaning direction of the mobile robot by using the coordinate values of the grid. When the mobile robot starts cleaning according to the cleaning start command, the position of the starting point of the previous cleaning is identified, and the height value and initial value of each grid of the two-dimensional grid map having the height information and obstacle information created as the mobile robot moves. An image signal processing unit dividing the cleaning target region into a plurality of sub-regions by using a height value; And
A control unit for setting a cleaning priority path by allocating a high cleaning priority to an area having a predetermined reference size or less among the divided sub areas, and selecting a next cleaning area in consideration of a moving path;
Mobile robot control device based on the past map data comprising a. The method of claim 7, wherein
The video signal processor,
A feature point extraction unit for extracting feature points from an image acquired from an image sensor; And
And a landmark matching unit for extracting a feature point candidate group through matching between a pre-created feature point map and the extracted feature point, and finding the starting point in the feature point candidate group. The method of claim 7, wherein
The control unit,
And extracting phase information from the two-dimensional grid map to extract at least one of an end point, a junction, and a connecting line, and calculating a distance information to the obstacle in proximity to the connecting line to obtain visit information. Mobile robot control device based on historical map data. 10. The method of claim 9,
The location estimator divides a room area by combining link information based on the set visited area, extracts link information included only in the partitioned room area, obtains a coordinate value of a grid occupied by the link, and coordinates of the grid. A mobile robot control apparatus based on past map data, wherein the cleaning direction of the mobile robot is determined using a value.

Images