JP2014211775A - Arrangement information creating method and mobile robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the necessity of update of arrangement information created on the basis of data measured with a distance measuring sensor mounted on a mobile robot.SOLUTION: An arrangement information creating method includes cutting out graphic elements on the basis of a change in radius vector of sensing data, evaluating the difference between the original arrangement data and re-created arrangement data, determining whether the difference is due to a change in arrangement of the graphics or simply an error in arrangement information, and further evaluating the value of the difference while changing the association between the sequence of coordinates of the original arrangement data and the sequence of coordinates of the re-created arrangement data to correct the correspondence between the original arrangement data and the re-created arrangement data.

Description

  The present invention relates to a method for creating placement information, and more particularly to a placement information creation method and a mobile robot created based on sensing data measured by a distance sensor mounted on a mobile robot.

  In some cases, such as a factory or a warehouse, arrangement information indicating the arrangement of objects in an area is locally changed at any time. In such a case, when creating placement information such as a map by the mobile robot system, it is necessary to recreate the placement information such as a map by moving the mobile robot within the region.

  On the other hand, if the placement information is created based on the sensing data measured by the distance sensor mounted on the mobile robot while moving through a passage such as a factory or warehouse, it is suitable for the passage side of each graphic element existing in the area. Arrangement information composed of a straight line or a curve obtained by projecting a surface onto a two-dimensional plane is obtained. Note that a straight line or a curve constituting the arrangement information is represented by a two-dimensional coordinate string.

  In a mobile robot system that moves while estimating its position and orientation by collating sensing data with location information such as a map, by continuously managing the map area necessary for estimating the position and orientation of the robot as a partial map, A technique for reducing the storage capacity and the processing time is disclosed in Patent Document 1.

JP 2009-163156 A

By the way, when the mobile robot is moved in the area and the layout information represented by the two-dimensional coordinate sequence is recreated, it is determined whether or not the layout information should be updated with the recreated information. There is a problem.
(1) Since each graphic element is not distinguished in the arrangement information represented by the two-dimensional coordinate sequence, it is difficult to determine whether the arrangement of each figure is changed or simply an error in the arrangement information from the change in the arrangement information. It is.
(2) Although the arrangement information is represented by a two-dimensional coordinate sequence, the original arrangement information and the re-created arrangement information are not associated with two-dimensional coordinates. It is difficult to compare the arrangement information with the newly created arrangement information.

  The present invention performs the following processing in order to solve the above problems.

A method for creating arrangement information by a mobile robot having processing means for processing data measured by a distance sensor for detecting a distance to an object,
From the data measured by the distance sensor, based on a change in the radius included in the data, cut out a line segment corresponding to the graphic element representing the object to generate actual measurement data,
For each of the cut out line segments, the difference between the original arrangement data held in advance and the actual measurement data is evaluated to determine whether the graphic element arrangement has changed or the arrangement information has an error.

  According to the present invention, based on the arrangement information represented by the two-dimensional coordinate sequence, the original arrangement information and the re-created arrangement information are associated with each other while there is an error in the arrangement information (that is, the arrangement information update). Further, the type of layout change of each figure can be determined.

It is a figure which shows the example of the arrangement | positioning figure which shows arrangement | positioning of the object in the area | region which applies a present Example. It is a figure which shows the system configuration | structure for implementing a present Example. It is a figure which shows the example of arrangement | positioning information. It is a figure which shows the processing flow of the arrangement | positioning information creation method in a present Example. It is a figure which shows the process which determines the change condition of each graphical element. It is explanatory drawing in the process of the determination of the same graphic element.

(layout drawing)
FIG. 1 shows an example of an arrangement diagram showing the arrangement of objects in a region to which this embodiment is applied. FIG. 1 shows the arrangement of devices and objects in a factory. The factory is divided into four areas (areas 1 to 4) by a path, and the mobile robot R moves along the path. In the following, the area that is the target of the layout drawing is referred to as “all areas”. The graphic elements P1 to P3 shown in each region of FIG. 1 are position fixing elements whose installation locations are fixed in advance, such as machine tools, and the graphic elements A, B, C, D, and E have installation locations. It is an element that may change. A broken line shows the arrangement detected by the mobile robot R last time, and a solid line shows the arrangement detected this time. Graphic element A shows a figure that has undergone “element rotation”, graphic element B shows a figure that has undergone “place movement”, graphic element C shows a figure that has “dimensional error”, and graphic element D has Shows a “newly installed” figure moved from another area to the corresponding area after detection, and the graphic element E was present at the previous detection but subsequently moved to another area. Indicates.

  The mobile robot R has a monitoring range (total θ) of a predetermined angle (θ / 2) on the left and right with respect to the traveling direction indicated by the arrow in FIG. Based on data measured in the monitoring range of the angle θ by the distance sensor mounted on the mobile robot R, a straight line portion or a curve obtained by projecting a plane facing the path side of each graphic element existing in the region onto a two-dimensional plane Arrangement information composed of portions (collectively, line segments) is obtained. The arrangement information includes arrangement data including an identification term of a graphic element corresponding to an object arranged in the region and a coordinate string representing the graphic element. The portions indicated by bold lines in the graphic elements A, B, C, and D in FIG. 1 are monitorable portions of the respective graphic elements obtained when the mobile robot R is at the position shown in FIG.

Mobile robot R is in the monitoring range of the angle theta, a minute angle Δθ increment, to measure the distance r _i to each graphic element from the mobile robot R. Accordingly, a polar data string {θ _i , r _i } consisting of an angle and a moving radius is obtained within the monitoring range of the angle θ, and an orthogonal coordinate data row {x of each graphic element is obtained from this angle and moving radius. _i , y _i } is obtained by x _i = x _P + r _i cos (θ _i + α), y _i = y _P + r _i sin (θ _i + α). However, i = 1 to n, and n is the number of data, | θ _i | ≦ θ / 2, | θ _{i + 1} −θ _i | = Δθ. Here, θ _i is an angle of monitoring with respect to the moving direction of the mobile robot R, (x _P , y _P ) is the position coordinate of the mobile robot R, and α is the position of the mobile robot R with respect to the positive x coordinate axis. It is the angle in the direction of movement.

The mobile robot R, so to measure the distance r _i to each graphic element while moving, whenever the mobile, because the same part of the observable portion of each graphic element is repeatedly measured, the amount of measurement data It becomes enormous and duplicate data increases. Therefore, when the mobile robot R moves throughout the entire area and creates a layout map of the entire area, the data in the already measured area is not registered as the layout information, or the data is not The amount of arrangement information can be reduced by performing processing such as thinning at intervals. It is assumed that the arrangement information in this embodiment has been subjected to the data amount reduction process as described above.

In the following description, the data string is expressed as {x _i , y _i }, for example, and the single data is expressed as (x _P , y _P ), for example.

(System configuration)
The configuration of the mobile robot R that executes this embodiment is shown in FIG. The mobile robot R is composed of a computer 20, in which a CPU 21, a memory 22, a storage device 24, and a distance sensor 26 for acquiring sensing data (actual measurement data) are connected via a bus. The memory 22 stores the correction program 23 of the present embodiment, and the storage device 24 stores the original arrangement information (the arrangement information measured last time) and the re-created arrangement information (the arrangement information measured this time). Including arrangement information 25 is stored. By connecting a terminal 30 having a display device to the computer 20, the user can check the arrangement information 25 stored in the storage device 24.

(Location information)
A configuration example of the arrangement information 25 is shown in FIG. The arrangement information 25 includes a number 25a, a graphic element 25b that is an identifier of each graphic element, the previous arrangement data 25c, the current arrangement data 25d, and the change status 25e of each graphic element. The arrangement data is composed of a data string of xy coordinates constituting each graphic element, for example, {x _{A, i} , y _{A, i} }.

Further, the xy coordinates in the previous arrangement data 25c are expressed in lower case letters, for example, {x _{A, i} , y _{A, i} }, and the xy coordinates in the current arrangement data 25d (actual measurement data) are For example, it is written in upper case letters such as {X _{A, i} , Y _{A, i} }. In the present embodiment, by comparing the previous arrangement data with the actual measurement data which is the latest data, it is determined whether or not the previous arrangement data stored in the storage device 24 is updated with the actual measurement data. That is, the actual measurement data becomes reference data for the previous arrangement data.

(Processing flow)
A processing flow of the correction program 23 executed in the CPU 21 is shown in FIG.

(A) Input of actual measurement data of arrangement (401)
The actual measurement data of the arrangement obtained by the mobile robot R measuring the entire area is input. Based on a change in the radius of sensing data, which is actual measurement data measured by a distance sensor mounted on the mobile robot R, a straight line or a curve (generically a line segment) corresponding to each graphic element is obtained from a two-dimensional coordinate sequence. ). That is, the value of the radius (r _i ) changes abruptly between two adjacent coordinate points (| r _{i + 1} −r _i |> δ _r , δ _r is used to determine the abrupt change in radius. Threshold value), it is determined that two adjacent coordinate points belong to different graphic elements. The actual measurement data of each graphic element cut out in this way is registered in the arrangement information 25 of FIG. 3 as current arrangement data 25d.

  It is possible to determine whether or not both graphic elements are the same by determining whether the place (coordinates) where the radius of abrupt changes is similar between the previous arrangement data and the current measurement data. As a result of the above determination, there is current measurement data as in the graphic element D in FIG. 3, but there is no data corresponding to the previous arrangement data, or in the previous arrangement as in the graphic element E in FIG. Although there is data, there may be no actual measurement data. When there is no corresponding data in this way, “−” is shown in FIG.

(B) Evaluation of arrangement data difference (402)
The difference between the actual measurement data measured by the distance sensor and the previous arrangement data 25c already stored in the arrangement information 25 of FIG. 3 is evaluated. The difference is evaluated according to the following procedure.

A deviation (dispersion) from the actual measurement data is _obtained for one graphic element Ak. That is, the dispersion _S k = graphic element _{A k (Σ i = 1~mk (} (x k, i -X k, i) 2 + (y k, i -Y k, i) 2)) / in _{m k} is there. Here, m _k is the number of two-dimensional coordinates constituting the graphic element A _k . Further, the deviation (dispersion) from the actual measurement data for the entire arrangement information is _obtained by S = (Σ _{k = 1 to n} S _k ) / n. Here, n is the number of graphic elements.

When evaluating the deviation of the entire arrangement information regardless of the graphic elements, the deviation (dispersion) S is expressed as S ′ = (Σ _{k = 1 to n} m _k S _k ) / (Σ _{k = 1 to n} m _k ) The numerator in S ′ is Σ _{k = 1 to n} Σ _{i = 1 to mk} ((x _{k, i} −X _{k, i} ) ² + (y _{k, i} −Y _{k, i} ) ² ), and the denominator is This is the total number of coordinate sets (coordinate points). S ′ is _obtained by replacing 1 / n of each term on the right side of S with m _k / (Σ _{k = 1 to n} m _k ). (M _k / (Σ _{k = 1 to n} m _k )) / (1 / n) = m _k / m, m = (Σ _{k = 1 to n} m _k ) / n is the number of coordinate points of the graphic element Average value.

(C) Overall error determination (403)
If the deviation σ = √ (S) or √ (S ′)> ε (the reference value of the total deviation), it is necessary to update the previous arrangement data stored in the storage device 24 with the actual measurement data. If the deviation σ = √ (S) or √ (S ′) ≦ ε, the previous arrangement data has not been changed, and the process ends without updating the arrangement data with the actual measurement data.

(D) Determination of change status of each graphic element (404)
The change status of each graphic element is determined by comparing the coordinate data of the previous layout data and the actual measurement data, and the determination result is stored in the change status 25e of the layout information 25 in FIG. Details of the processing in step 404 will be described later with reference to FIG.

(E) Update of arrangement information by actual measurement data (405)
The previous arrangement data stored in the storage device 24 is updated with the actual measurement data.

(F) Identification display of changed graphic element (406)
Using a dispersion _{S k} graphic element _{A k} calculated in step 402, the deviation sigma _k = √ graphic element _{A k (S k)> δ} EL ( reference value [delta] _EL <epsilon overall deviation of the deviation of the graphic element units the graphic element a _k particularly large deviation becomes a reference value) of, it is also possible to identify and display on arrangement information displayed on the screen of the terminal 30.

(Judgment of change status)
FIG. 5 shows details of the process for determining the change status of each graphic element in step 404 of FIG.

  When determining the change status of each graphic element by comparing the coordinate data of the previous arrangement data and the actual measurement data, each of the previous arrangement data and the actual measurement data is determined even if the graphic element is moved or rotated. Determine whether graphic elements are identical.

In step 501, it is confirmed whether a graphic element (corresponding to a corner of a polygonal figure) in which two straight line parts are connected at a predetermined angle can be determined as the same graphic element in the previous arrangement data and measured data. To do. Thereafter, the graphic element change status after step 502 is determined for the graphic elements determined to be the same. In order to determine movement or rotation of a graphic element, a graphic element consisting of at least three points is required. The movement and rotation of a graphic element cannot be determined with a simple straight line portion. In the determination of the same graphic element, a data string {θ _i , r _i } composed of an angle and a moving radius measured by a distance sensor mounted on the mobile robot R is used. Details of determination of the same graphic element will be described later with reference to FIG.

  As described above, the change state determination process in steps 502 to 512 is performed on the graphic elements determined as the same graphic element in the previous arrangement data and the actual measurement data.

  When the actual measurement data 25d does not exist in the previous arrangement data 25c as in the graphic element D in the arrangement information 25 in FIG. 3 (502), it is determined as “new installation” (503). When the actual measurement data 25d corresponding to the previous arrangement data 25c does not exist as in the graphic element E in the arrangement information 25 of FIG. 3 (504), it is determined as “element deletion” (505).

Using a dispersion _{S k} graphic element _{A k} calculated in step 402, the deviation of the graphic element _{A k (error) σ k = √ (S k} )> δ EL ( reference value [delta] _EL shift graphic element units <epsilon It is determined whether or not the deviation is large (reference value of overall deviation) (506). If the deviation is large, Step 510 and subsequent steps are executed. Otherwise (error σ _k ≦ δ _EL deviation reference value), it is determined whether the error of the graphic element A _k is sufficiently smaller than the deviation reference value δ _EL of the graphic element unit (507). If it is sufficiently smaller than the reference value of deviation, the graphic element is determined to be an element whose position is fixed, such as P1 and P2 in FIG. 1 (508). Is corrected (509).

  In step 510, it is determined whether or not the sign of the x or y component of the difference vector connecting the corresponding points of the actual measurement data 25d and the previous arrangement data 25c is the same in each difference vector. If the signs are the same, it is determined as “location movement” (512). In the case of “place movement”, the respective difference vectors are parallel to each other. On the other hand, if the signs are not the same, it is determined as “element rotation” (511). In the case of “element rotation”, the direction of each difference vector rotates in the clockwise direction or the counterclockwise direction.

  By the above processing, not only the determination as to whether or not there is a change between the previous arrangement data and the actual measurement data, but also the change status of each graphic element can be grasped when there is a change.

(Judgment of the same graphic element)
FIG. 6 shows the same graphic element determination processing in step 501 of FIG. The graphic element to be determined is a graphic element in which the straight line portion S-M and the straight line portion M-E are connected at an angle φ with the point M. The length of the straight line portion of SM is R1, the length of the straight portion of ME is R2, and the length of the straight portion of SE shown by the broken line is R3. Hereinafter, the graphic element to be determined is abbreviated as SME.

  When the mobile robot R is located at the point O, the radiuses of S, M, and E are r1, r2, and r3, respectively, and the angle formed by the two radiuses r1 and r2 is Δθ1, two radiuses r2, and Assuming that the angle formed by r3 is Δθ2, R1, R2, and R3 use the equations (1), (2), (3) in FIG. 6 using r1, r2, r3, Δθ1, and Δθ2 obtained by the distance sensor. ). Further, the angle φ is expressed as shown in the equation (4) in FIG. 6 using R1, R2, and R3 obtained by the equations (1), (2), and (3) in FIG.

  When the mobile robot R is positioned (moved) at the point O ′, the radiuses of S, M, and E are r1 ′, r2 ′, and r3 ′, respectively, and the angles formed by the two radiuses r1 ′ and r2 ′. R1 ′, R2 ′, R3 ′, Δθ1 ′, R1 ′, R2 ′, and R3 ′ obtained by the distance sensor, where Δθ1 ′ is the angle formed by the two radials r2 ′ and r3 ′, and Δθ2 ′. And Δθ2 ′ are expressed as shown in equations (5), (6), and (7) of FIG. Further, the angle φ ′ is expressed as shown in equation (8) of FIG. 6 using R1 ′, R2 ′, and R3 ′ obtained by equations (5), (6), and (7) of FIG. Is done.

  Expressions (1) to (4) are relational expressions of the arrangement information corresponding to the previous arrangement data, and expressions (5) to (8) are relational expressions of the arrangement information corresponding to the current arrangement data (actual measurement data). In order to determine that the graphic element SME based on the previous arrangement data and the graphic element SME based on the actual measurement data are the same graphic element, the equations (1) to (8) in FIG. It is only necessary that the length and angle of the straight line portion obtained from the equation (9) satisfy the condition. The conditional expression (9) in FIG. 6 may not be a strict equal sign but may be established within a predetermined error range.

(Correction of correspondence of arrangement information)
In the above embodiment, for each graphic element, each of a plurality of coordinates constituting the graphic element corresponds between the previous arrangement data and the current arrangement data (actual measurement data), and the coordinate point It was described that the numbers were the same. However, since the movement path of the mobile robot when the previous arrangement data is acquired is not exactly the same as the movement path of the mobile robot when the current arrangement data is acquired, the previous arrangement data and There is a possibility that the plurality of coordinates constituting the graphic element do not correspond to the arrangement data this time, and the number of coordinate points is not the same.

  On the other hand, in this embodiment, based on the sensing data measured by the distance sensor mounted on the mobile robot R, the presence / absence of the change of the arrangement information in the entire area is detected, and the change status of each graphic element is grasped. Therefore, it is not necessary to have all the arrangement data related to each graphic element, and it is sufficient if there is arrangement data that can achieve the above-mentioned purpose.

  Therefore, in step 402 in FIG. 4, when the difference between the original arrangement data and the re-created arrangement data is evaluated and it is determined whether the arrangement change of each figure or a simple arrangement information error, The correspondence between the arrangement data coordinate sequence and the recreated arrangement data coordinate sequence is corrected as follows. Hereinafter, correction of the correspondence relationship when the original arrangement data is associated with the actual measurement data will be described with reference to the re-created arrangement data.

The coordinate sequence of the original arrangement data is {x _{A, i} , y _{A, i} } (i = 1 to n), and the coordinate sequence of the actual measurement data is {X _{A, j} , Y _{A, j} } (j = 1 to 1). m), and the coordinate sequence correspondence is moved point by point as follows, and the difference between the original arrangement data and the actual measurement data is evaluated in the same manner as in step 402 in FIG. The correspondence relationship between the original arrangement information and the actually measured data is corrected based on the amount of movement. That is, when the value of the difference between the original arrangement data and the actual measurement data is minimized, it is estimated that the coordinate sequence of the original arrangement data corresponds to the coordinate sequence of the actual measurement data. The following association is performed according to the magnitude relationship of the number of coordinate points (n, m) included in the respective coordinate sequences of the original arrangement data and the actual measurement data.

In the case of n <m, the portion associated with the original arrangement data is moved within the range of the actual measurement data, and first {x _{A, i} , y _{A, i} } (i = 1 to n) and {X _{A, j} , Y _{A, j} } (j = 1 to n) are made to correspond (movement amount = 0), then {x _{A, i} , y _{A, i} } (i = 1 to n) and {X _{A, j} , Y _{A, j} } (j = 2 to n + 1) are made to correspond (movement amount = 1),..., And finally {x _{A, i} , y _{A, i} } (i = 1 to n) and {X _{A , J} , Y _{A, j} } (j = mn + 1 to m) are associated (movement amount = mn), and the original arrangement data and The correspondence with the actual measurement data is corrected.

If n ≧ m, the portion associated with the actual measurement data is moved within the range of the original arrangement data, and the first {x _{A, i} , y _{A, i} } (i = 1 to _m ) and {X _{A, j} , Y _{A, j} } (j = 1 to m) are made to correspond (movement amount = 0), then {x _{A, i} , y _{A, i} } (i = 2 to m + 1) and {X _{A, j} , Y _{A, j} } (j = 1 to m) are made to correspond (movement amount = 1),..., And finally {x _{A, i} , y _{A, i} } (i = n−m + 1 to n) and { X _{A, j} , Y _{A, j} } (j = 1 to m) are made to correspond (movement amount = nm), and based on the movement amount that minimizes the difference value, the original arrangement data and The correspondence with the actual measurement data is corrected.

20: Computer (robot), 21: CPU, 22: Memory, 23: Correction program, 24: Storage device, 25: Arrangement information, 26: Distance sensor, 30: Terminal (display device)

Claims (5)

A method for creating arrangement information by a mobile robot having processing means for processing data measured by a distance sensor for detecting a distance to an object,
From the data measured by the distance sensor, based on a change in the radius included in the data, cut out a line segment corresponding to the graphic element representing the object to generate actual measurement data,
For each of the cut out line segments, by evaluating the difference between the original arrangement data held in advance and the actual measurement data, it is determined whether the graphic element arrangement change or arrangement information error,
An arrangement information creation method characterized by this.   Based on the amount of change between the coordinate sequence of the original arrangement data and the coordinate sequence of the actual measurement data, the type of arrangement change of the graphic element is any one of new installation, element deletion, location movement, or element rotation The arrangement information creating method according to claim 1, wherein the arrangement information is determined.   Evaluating the value of the difference while moving the coordinate sequence of the original arrangement data and the coordinate sequence of the actual measurement data by one coordinate point, based on the movement amount that minimizes the value of the difference, 2. The arrangement information creation method according to claim 1, wherein a correspondence relationship between the original arrangement data and the actual measurement data is corrected.   The graphic element that is the target of the type determination of the arrangement change is a graphic element in which the first straight line portion and the second straight line portion are connected at the first angle at the connection point of the first and second straight line portions. And determining whether the length of the first straight line portion, the length of the second straight line portion, and the first angle are equal between the original arrangement data and the actually measured data. The arrangement information creating method according to claim 2, wherein it is determined whether or not the graphic elements of the original arrangement data and the actual measurement data are the same. A mobile robot that creates arrangement information of an object in a movable area while moving in a predetermined area,
A data processing means, a storage device, and a distance sensor that measures a distance to a graphic element in the region within a monitoring range of a predetermined angle;
The data processing means includes
Means for cutting out a line segment corresponding to each graphic element from the two-dimensional coordinate sequence obtained from the sensing data measured by the distance sensor and generating actual measurement data based on a change in the radius of the sensing data; and For each of the cut out line segments, by evaluating the difference between the original arrangement data stored in advance in the storage device and the actual measurement data, it is possible to determine whether the graphic element arrangement has changed or the arrangement information has an error. Means to determine,
A mobile robot characterized by comprising:

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