JP4462173B2 - Autonomous mobile device - Google Patents

Description

  The present invention relates to an autonomous mobile device that recognizes its own position and direction and moves autonomously.

  Conventionally, an autonomous mobile device that autonomously moves in a predetermined movement area such as a factory or a public facility has been used. Autonomous mobile devices perform work such as transporting objects and places where people cannot enter. At this time, in order for the autonomous mobile device to work accurately and safely, it is necessary for the autonomous mobile device to accurately recognize its own position (positional coordinates) in the global coordinate system set in the movement area. Further, for example, in order to accurately face a person or work place, the autonomous mobile device needs to accurately recognize the direction (posture) that the user is facing.

  There is a dead reckoning technology that allows the autonomous mobile device to recognize its own position. The dead reckoning technique is, for example, a technique for calculating a movement amount (movement distance and movement direction) by accumulating the rotation amount of a wheel and obtaining a current position by integrating the movement amount from an initial position. Although this dead reckoning technique is low-cost, it has a drawback that as the travel distance increases, the measurement error of the moving amount accumulates and the recognized self-position and direction deviate from the true value.

Therefore, in order to periodically eliminate the measurement error of the dead reckoning technology, an RFID (Radio Frequency Identification) technology can be used. For example, a large number of RFID tags and cards having coordinate information recorded therein are embedded in the movement area of the autonomous mobile device, and the mobile robot reads the RFID tags and cards during movement to acquire coordinate values in the global coordinate system and The absolute position of can be recognized. As an example of application, for example, by reading a large number of RFID cards and processing a plurality of obtained position coordinate values by the least square method, the autonomous position that recognizes its absolute position from a large number of information more accurately and moves A moving device is known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2004-21978

  However, in the above-described technology and the autonomous mobile device as shown in Patent Document 1, the coordinate origin recognized by the coordinate system recognized by itself is shifted from the global coordinate system, or the direction is shifted by rotation. However, there is no disclosure of correcting and recognizing the direction (posture) that the user is facing.

  An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an autonomous mobile device capable of accurately recognizing the direction in which the user is facing together with the position of the user by acquiring position coordinates a few times.

In order to achieve the above object, the invention of claim 1 is an autonomous mobile device that moves autonomously, and includes first position information using dead reckoning that acquires its position and direction from its own motion information. It has an acquisition means, a storage unit that stores an environment information map of the area where it moves, and a sensing unit that acquires environment information, and stores the ambient environment information acquired using the sensor of the sensing unit and the storage unit Information about a plurality of self-positions received by the antenna, the second position information obtaining means for obtaining the position and direction of the self by comparing with the environmental information map, and an antenna for receiving information from the outside The third position information acquisition means for calculating the position and direction of itself is compared with the position and direction of the self acquired by the first, second, and third position information acquisition means. And a control means for determining the position and direction of the current self, and said control means, autonomous upon movement of the mobile device, the second or third position information acquired from the location that can be recognized correctly position and direction Until the position where the position and direction of the user are acquired by the means, the position and direction of the user are determined by the first position information acquisition unit, and the position and direction of the user are acquired by the second position information acquisition unit. The first or second position information acquisition is performed by correcting the position and direction of the first position information acquisition unit according to the position and direction and acquiring the position and direction of the first position information acquisition unit. the position and orientation unit has acquired, and the third location information acquisition unit position and orientation acquired is, when there is a large difference than a predetermined value during the comparison shiso the previous It is intended to determine the position and orientation third position information acquisition unit acquires as the position and direction of the current self.

According to a second aspect of the present invention, in the autonomous mobile device according to the first aspect, the control means recognizes the position and direction of the position acquired by the third position information acquisition means by the second position information acquisition means. The second position information acquisition unit performs at least a re-confirmation operation when the second position information acquisition unit is in a specific area within the movement area where the movement can be accurately performed .

  According to the first aspect of the present invention, the error caused by the first and second position information acquisition means is corrected by the position and direction information obtained by the third position information acquisition means. Can recognize itself accurately and move autonomously. Since the third position information acquisition means compensates the first and second means and does not need to function constantly, for example, when an RFID tag is used as the third means, the traveling area of the autonomous mobile device RFID tag setting areas can be interspersed, and labor and cost for setting RFID tags can be reduced.

  According to the invention of claim 2, the self-direction can be reconfirmed by the second position information acquisition means in the predetermined specific area. By the way, when acquiring environmental information of surroundings such as a wall surface and comparing it with the environmental information map, if you acquire more environmental information, the accuracy increases, but more It takes time and cannot move efficiently. Therefore, for example, by registering a predetermined area where useful environmental information can be easily obtained, and reconfirming the position and direction of the self in the predetermined area, the position and direction of the self can be obtained more accurately in a shorter time. Can be corrected.

  Hereinafter, an autonomous mobile device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block configuration of an autonomous mobile device 10 of the present invention, and FIG. 2 shows an autonomous mobile device 10 and its moving environment. The autonomous mobile device 10 is a device that moves autonomously, and includes first position information acquisition means 1 that uses dead reckoning that acquires its own position and direction based on its own motion information, and a region in which it moves. It has a storage unit 21 for storing an environmental information map and a sensing unit 22 for acquiring environmental information, and compares the surrounding environmental information 6 acquired using the sensor of the sensing unit 22 with the environmental information map stored in the storage unit 21. The second position information acquisition means 2 for acquiring the position and direction of itself, and the antenna 31 for receiving information from the outside (for example, the RFID tag 5), and a plurality of self-positions received by the antenna 31. Based on the information, the third position information acquisition means 3 for calculating the position and direction of the self, and the positions of the self acquired by the first, second, and third position information acquisition means 1, 2, 3 And comparing the direction and a control unit 4 to determine the position and direction of the current self, a.

  The control means 4 is larger than a predetermined value between the position and direction acquired by the first or second position information acquisition means 1 and 2 and the position and direction acquired by the third position information acquisition means 3. When there is a difference, the position and direction acquired by the third position information acquisition unit 3 are determined as the current position and direction. In other words, the control means 4 preferentially determines the position and direction acquired by the third position information acquisition means 3 as the current position and direction of itself. The control means 4 includes a central control unit (CPU) configured using a microprocessor (MPU) and the like, and peripheral devices for input / output.

  As described above, the autonomous mobile device 10 stores and stores its own position and direction acquired by the first, second, and third position information acquisition units 1, 2, and 3 under the control of the control unit 4. Based on the environmental information map stored in the unit 21, the self-position is corrected, and the vehicle travels to the destination while recognizing the direction in which it is facing (that is, its own posture).

  As shown in FIG. 2, the autonomous mobile device 10 includes left and right drive wheels 11 and four corner auxiliary wheels 11 a. The left and right drive wheels 11 are independently controlled, and can move forward, rotate, and retreat depending on the difference in rotation speed. The rotation center Q is a representative point indicating the position of the autonomous mobile device 10, and is at the intermediate point between the two drive wheels 11. Further, the drive wheel 11 includes an encoder 12 that detects the rotation speed and rotation speed thereof. Based on the output of the encoder 12, the first position information acquisition unit 1 acquires the travel distance and travel direction (rotational movement amount) of the autonomous mobile device 10, integrates the information, and obtains the autonomous mobile device 10. The current position and direction of travel are acquired and output.

  In addition, the autonomous mobile device 10 is provided with a sensor of the sensing unit 22 that acquires the environment information 6 on the front surface of the autonomous mobile device body so as to sense at least a region in the traveling direction. As this sensor, for example, a laser range finder, an ultrasonic sensor, an array type ultrasonic sensor, a radar, or the like can be used. Two cameras arranged with a predetermined separation distance can be used. By processing the images acquired by these cameras, the distance can be recognized and a distance image serving as environment information can be generated.

  Further, the autonomous mobile device 10 includes an antenna 31 for receiving information on the RFID tag on the bottom surface thereof. For example, a predetermined number of RFID tags 5 are arranged at predetermined intervals on a traveling surface of a moving area of the autonomous mobile device 10. The antenna 31 is provided by arranging the antenna center p at a position forward of the distance tr from the rotation center Q of the autonomous mobile device 10. When the RFID tag 5 roughly enters the rectangular area around the antenna center p, information on the RFID tag 5 can be read. The size of the RFID tag 5 and the size of the antenna 31 may be dimensions that allow the RFID tag 5 to be read. In general, the smaller these dimensions, the better the reading position accuracy, but the reading sensitivity decreases. The reading sensitivity depends on the distance between the RFID tag 5 and the antenna 31. Generally, the reading sensitivity increases as they are closer to each other. There is no limitation on the arrangement interval and number of RFID tags.

  Here, three coordinate systems uv, XY, and xy are defined. The coordinate system uv is a coordinate system that moves and rotates together with the autonomous mobile device 10. The origin of the coordinate system uv is at the rotation center Q of the autonomous mobile device 10, and has the u axis in the forward direction of the autonomous mobile device 10 and the v axis in the direction orthogonal thereto. The coordinate system XY is a global coordinate system, and is a coordinate system that uniquely represents an area in which the autonomous mobile device 10 moves. That is, the coordinate system XY is a coordinate system fixed to the movement area of the autonomous mobile device 10, and can be regarded as an absolute coordinate system. The environment information map stored in the storage unit 21 is normally expressed in this global coordinate system XY. The position of the autonomous mobile device 10 is represented by the position of the center Q in the coordinate system XY.

  The coordinate system xy is a global coordinate system recognized by the autonomous mobile device 10. In this coordinate system xy, the positional relationship and rotational relationship with the coordinate system XY change depending on the movement state of the autonomous mobile device 10. That is, while the autonomous mobile device 10 can accurately recognize its own position and direction by the first, second, and third position information acquisition means 1, 2, 3, the coordinate system xy It is consistent with the system XY. However, for example, when the autonomous mobile device 10 slips during dead reckoning and translates or rotates, the two coordinate systems xy and XY are displaced from each other in the origin and between the coordinate axes of each other. The relationship has a rotational deviation.

  Here, how the autonomous mobile device 10 travels will be described. As described above, the autonomous mobile device 10 acquires information on the position and movement direction that depends only on its own internal information, which is output from the encoder 12, via the first position information acquisition means 1, and Based movement (movement by so-called dead reckoning). In the movement by dead reckoning, the autonomous mobile device 10 estimates the moving distance from the rotational speed of the wheel obtained from the encoder 12 attached to each driving wheel 11 and its geometrical arrangement, thereby moving while estimating its own position. To do. Therefore, when a wheel slips or the like, a difference between the position estimated by dead reckoning and the actual position of the autonomous mobile device 10 occurs, and the acquired environmental information and the map information of the environmental information map can be collated. There is a possibility that it may disappear or enter a place that should not be entered.

  In order to avoid this, the autonomous mobile device 10 has environmental information 6 such as a wall, a pillar, a landmark, or a structure or a label in the movement area as map information on the environmental information map, The environment information 6 is acquired and recognized via the position information acquisition means 2 and moved while collating with the map information. In this case, the current self-recognized position can be corrected by recognizing the environment and collating with the map. Then, from the position where the position is correctly recognized to the position where the collation with the next map is successful, the estimated movement is due to dead reckoning, but it is possible to move while avoiding an increase in error due to dead reckoning.

  Further, in order for the autonomous mobile device 10 to acquire position information with no error via the third position information acquisition unit 3, a predetermined place, for example, a place where the environment information 6 to be compared with the map information is difficult to obtain, The RFID tag 5 is buried in, for example, a traveling surface such as a place where collation is difficult even if the environment information 6 is obtained, or a periphery of a boundary to an area where entry is not allowed. As the RFID tag 5 buried in the moving surface, a passive tag can be used. Such a tag 5 is supplied with power by a non-contact power transmission technique by radio waves from an antenna 31 (hereinafter referred to as an RFID reader 31) attached to the bottom surface of the autonomous mobile device 10, and autonomously stores position information stored in advance. Transmit to mobile device 10. Thereby, the autonomous mobile device 10 can obtain position information.

  The position information obtained from the tag 5 is, for example, the position coordinate value of the tag 5 in the global coordinate system XY or the ID of the tag 5 previously associated with the position coordinate value in the global coordinate system XY. The autonomous mobile device 10 can know the absolute position in the global coordinate system XY based on the position information transmitted from the tag 5 and received by the reader 31.

  However, when only one piece of position information is obtained, the autonomous mobile device 10 can only know the position coordinate value on the global coordinate system XY, and the direction in which it is facing is unknown. Accordingly, the positional relationship between the coordinate system recognized by itself (hereinafter, coordinate system xy) and the global coordinate system XY is not determined. Then, as described above, for example, when the autonomous mobile device 10 slips during dead reckoning and translates or rotates, these two coordinate systems are based on the misalignment of the origin of each other and the coordinate axes. The positional relationship has a rotational deviation. That is, with only one absolute position information, the direction of movement of its own remains unclear, and information on which direction it faces in the global coordinate system XY cannot be obtained.

  Note that the positional relationship between the coordinate system xy recognized by the self and the global coordinate system XY is, as will be described later, coordinate values (X1, Y1), (X2, Y2) of two different points in the coordinate system XY. And the coordinate values (x1, y1) and (x2, y2) of the two points in the coordinate system xy can be determined. This is because, for example, two points are marked on a transparent sheet for the coordinate system xy and a transparent sheet for the coordinate system XY, and the two transparent sheets are overlapped, and the point on one sheet is the other. It can be understood from the fact that the two coordinate systems xy and XY can be made to coincide with each other without any deviation or rotation if they overlap with the points on the sheet. However, the movement direction of the autonomous mobile device 10 is the same, but the attitude of the autonomous mobile device 10 is not determined only by the point indicating the current position, but depends on the movement route to that point and the movement route after that point. That is, on the premise that there is no slip in the drive wheel 11, the tangential direction of the movement path of the autonomous mobile device 10 that proceeds toward the front direction is the posture of the autonomous mobile device 10.

  Next, the determination of the position and direction of the autonomous mobile device 10 using the third position information acquisition means 3 will be described with reference to FIGS. 3 and 4 in addition to FIG. 2 (FIGS. 3 and 4). The intersections of the coordinate axes of the coordinate systems xy and XY shown are points A and B, but the points A and B are not the origin). The autonomous mobile device 10 shown in FIG. 2 includes one RFID reader 31 having a center p at a forward distance t from its own center Q. It is assumed that such an autonomous mobile device 10 has moved from point A to point B as shown in FIG. Points A and B are positions of the center Q of the autonomous mobile device 10. The coordinate values of the points A and B in the coordinate system xy and the coordinate system XY are point A (x1, y1), (X1, Y1) and point B (x1, y1), (X1, Y1).

  The movement between the points A and B is not limited to a linear movement, and can move along an arbitrary trajectory. However, at least the coordinate values of the points A and B in the coordinate system xy can be accurately obtained by the first position information acquisition unit 1 (dead reckoning), and the points A and B are acquired by the third position information acquisition unit 3. Assume that position information is obtained from the RFID tag 5 in FIG.

  Since the movement between the points A and B is not necessarily a straight line, the front directions a and b of the autonomous mobile device 10 at the points A and B (the direction of the u axis in the coordinate system uv without losing generality) are respectively There are angles θ1 and θ2 with the x-axis of the coordinate system xy, and the deflection angle dθ is dθ = θ2−θ1. These angles θ1, θ2, and dθ are known and can be acquired by the first position information acquisition unit 1 (dead reckoning). Further, when an angle representing the attitude of the autonomous mobile device 10 with respect to the coordinate axis X at the point A (an angle formed by the front direction a and the coordinate axis X) is an angle θp, the angle θp is unknown. Further, when this angle θp is used, the rotation angle α of the coordinate system xy with respect to the coordinate system XY becomes α = θp−θ1, as shown in FIG.

In each coordinate system xy, XY, the movement distances along the coordinate axes from the point A to the point B are (dx, dy), (dX, dY), respectively. As described above, (dx, dy) is a known number, and (dX, dY) is an unknown number. However, if the distance between the points A and B is W, there is a relationship of W ² = dx ² + dy ² = dX ² + dY ² .

  When the autonomous mobile device 10 is at points A and B, the position of the RFID tag 5 can be regarded as the position of the center p of the RFID reader 31. The coordinate value in the coordinate system XY of the RFID tag 5 is a known amount read by the reader 31, and is (Xt1, Yt1) and (Xt2, Yt2) at points A and B, respectively. Using these coordinate values, the above-described matters, the angles θ1, θ2, dθ, and the distance t from the center Q of the autonomous mobile device 10 to the RFID tag 5, as shown below, for example, a point A The position and direction of the autonomous mobile device 10 with respect to the coordinate system XY (that is, the angle θp) can be obtained.

When (dX, dY) is obtained from the coordinate values (X1, Y1) and (X2, Y2) of the points A and B,
dX = Xt1−t × cos (θp) − (Xt2−t × cos (θp + dθ)),
dY = Yt1−t × sin (θp) − (Yt2−t × sin (θp + dθ)). By substituting these equations into the right side of dx ² + dy ² = dX ² + dY ² , the unknown θp can be obtained. When the unknown θp is obtained, the coordinate values (X1, Y1) and (X2, Y2) of the points A and B can be obtained. That is, the third position information acquisition unit 3 determines the position and direction of the autonomous mobile device 10.

  As described above, the position and direction of the autonomous mobile device 10 with respect to the coordinate system XY (that is, the angle θp, the attitude of the autonomous mobile device 10) can be easily obtained. This is because the RFID reader 31 is provided at a position away from the rotation center Q as a point by a non-zero distance (t ≠ 0). The same applies to the case where a plurality of RFID readers 31 described below are provided.

  Next, an autonomous mobile device including a plurality of RFID readers 31 will be described with reference to FIGS. The autonomous mobile device 10 described above has only one RFID reader 31 (FIGS. 2 and 3). The RFID reader 31 is not limited to one, and a plurality of RFID readers 31 can be provided. The autonomous mobile device 10 shown in FIG. 5 includes four RFID readers 31 around the rotation center Q on the bottom surface thereof. The centers p1, p2, p3, and p4 of each reader 31 are located at positions r1, r2, r3, and r4 from the rotation center Q, respectively. That is, each reader 31 has position coordinates determined in the coordinate system uv, and any one of these readers reads the RFID tag 5, whereby the coordinates Q in the coordinate system XY indicated by the center Q of the autonomous mobile device 10 and the RFID tag 5. The relationship with the value is confirmed.

  The coordinate relationship shown in FIG. 6 is a generalization of the coordinate relationship for one RFID reader 31 shown in FIG. In this figure, when the autonomous mobile device 10 is located at the point A, the point T1 is a distance tr1 from the center Q (not shown) located at the point A and the front direction a (coordinate system of the autonomous mobile device 10). This indicates the position of the RFID reader 31 at a position that is swung by the angle θr1 from the u-axis (u-axis direction). Show. The same applies to the point T2.

  Therefore, the autonomous mobile device 10 having a plurality of such RFID readers 31 moves between two points A and B and reads the RFID tag 5 at each point A and B, so that the unknown θp, The coordinate values (X1, Y1) and (X2, Y2) of the points A and B can be obtained.

  In addition, the autonomous mobile device 10 including the plurality of RFID readers 31 may read two RFID tags 5 at the same time when the arrangement interval of the RFID tags 5 embedded in the floor surface is appropriately set. it can. Then, in this case, the autonomous mobile device 10 associates the position of its own center Q with the two points of the coordinate system XY by combining two pairs of the RFID reader 31 and the RFID tag 5 at a certain point A. And the direction of the u-axis of its own coordinate system uv can be determined in the coordinate system XY.

  Next, referring to the flow of FIG. 7, the autonomous mobile device 10 uses the first, second, and third position information acquisition means 1, 2, 3 to determine its own position (coordinate values in the coordinate system xy). The operation when moving while recognizing (representation) and direction (orientation or orientation, which is represented by the angle formed by the front direction of itself with respect to the coordinate axis of the coordinate system xy) will be described. When the autonomous mobile device 10 starts moving toward a predetermined destination (S1), the control means 4 uses the first position information acquisition means 1 to obtain position information (this is a coordinate in the coordinate system xy). (Hereinafter, referred to as first position information, and the same applies to other position information), and the acquisition operation is repeatedly performed under a predetermined control period ( S2). When the first position information is acquired, the information is reflected in position recognition. That is, the coordinate value and direction of the autonomous mobile device 10 in the coordinate system xy are updated (S3). When the control means 4 determines that the autonomous mobile device 10 has reached the destination by updating the coordinate value and the direction, the control device 4 stops the autonomous mobile device 10 and ends the process (Yes in S4). If it is determined that it has not reached, the movement is continued (No in S4).

  The control means 4 operates the second position information acquisition means 2 periodically, for example, or when the autonomous mobile device 10 reaches a predetermined area of the environment information map stored in the storage unit 21, for example. Thus, when the second position information is acquired (Yes in S5), the information is reflected in position recognition. In other words, this process is a process of making the coordinate system xy coincide with the coordinate system XY and obtaining the correct self posture.

  Next, when the third position information acquisition unit 3 does not acquire the third position information (No in S7), the control unit 4 returns the control to step S1 and passes through the first position information acquisition unit 1. The autonomous mobile device 10 is moved while acquiring the first position information.

  When the third position information acquisition unit 3 acquires the third position information (Yes in S7), the control unit 4 determines the coordinate value and direction on the coordinate system xy recognized at the present time and the third position. It is compared whether or not the difference between the coordinate value and the direction on the coordinate system xy obtained based on the information is larger than a predetermined value (S8). The size comparison of the difference between the coordinate value and the direction is performed by, for example, individually obtaining a difference with respect to the x-coordinate value, the y-coordinate value, or the direction (angle), which are coordinate components, Instead of the y coordinate value, the distance between the coordinates is obtained and compared with a predetermined value. In this comparison, if the predetermined value to be compared with the difference between the coordinate value and the direction is too small, the coordinate value and the direction in the coordinate system xy are frequently corrected, and the movement speed of the autonomous mobile device 10 is corrected by the correction work. Therefore, it is desirable that the predetermined value is determined according to the characteristics of the autonomous mobile device 10.

  As a result of the process of step S8 described above, the difference between the coordinate value and orientation on the coordinate system xy currently recognized and the coordinate value and orientation on the coordinate system xy based on the third position information is greater than a predetermined value. In the case (Yes in S8), the control means 4 updates the coordinate value and orientation on the coordinate system xy with the coordinate value and orientation on the coordinate system xy based on the third position information (S9). If the difference is smaller than the predetermined value (No in S8), the control unit 4 returns control to Step S1 and autonomously moves while acquiring the first position information by the first position information acquisition unit 1. The apparatus 10 is moved. In this way, the autonomous mobile device 10 corrects the coordinate value and orientation on the coordinate system xy recognized at the present time with the coordinate value and orientation on the coordinate system xy based on the second position information or the third position information. By doing so, it is possible to obtain the correct position and self posture in the coordinate system XY, and to prevent the occurrence of problems that move in unexpected directions and to enter outside the planned moving area, and to correctly and efficiently Can be reached.

  Next, a description will be given of performing a reconfirmation operation of acquiring at least the direction of the user by the second position information acquisition unit when the position acquired by the third position information acquisition unit is within a predetermined region. As described above, when the third position information is obtained, the autonomous mobile device 10 corrects the current position and direction. However, since the third position information may include an error due to a malfunction of the RFID tag 5 or a reception error of the RFID reader 31, the autonomous mobile device 10 performs such reconfirmation operation.

  By the way, the error between the position of the autonomous mobile device 10 that can be recognized from the position obtained by the third position information acquisition means 3 and the actual position is considered to be about the size of the RFID reader 31 or the RFID tag 5. It is considered that the autonomous mobile device 10 is sufficiently small for autonomous movement. Accordingly, if at least the direction toward the autonomous mobile device 10, that is, the angle θp (FIGS. 3 and 6) can be obtained more accurately, it is effective for accurate autonomous movement.

  Therefore, a specific area within the moving area where the position and direction can be recognized with high accuracy by the second position information acquisition means 2 is determined, and this is registered in advance as a predetermined area in the environment information map. After the mobile device 10 corrects the position based on the third position information in the area and then starts moving, it once moves to a predetermined position confirmation point and reconfirms the position and direction. The operation is to be performed.

  As a reconfirmation method by the second position information acquisition unit 2 described above, for example, the position of a wall in the environment is detected, the detected wall, and a wall registered in the environment information map stored in the storage unit 21 Can be used to re-check the position and direction of the wall, and thus the position and direction of the autonomous mobile device 10. As a method for detecting a wall in the environment, for example, there is a method of sensing the surrounding environment by performing an angle scan using a laser range finder, and extracting a wall from sensing information which is an angular distribution set of obtained measurement points. (Literature: Li Zhang, Bijoy K. Ghosh, “Line Segment Based Map Building and Localization Using 2D Laser Rangefinder,” IEEE Int. Conf.

  Here, the operation when the autonomous mobile device 10 performs the position reconfirmation operation will be described with reference to the flow of FIG. The autonomous mobile device 10 starts moving toward the destination (# 1), determines whether or not the destination has been reached, and continues to move (No in # 2) or ends (Yes in # 2). ). When the autonomous mobile device 10 does not correct the current position and direction with the third position information during movement, the autonomous mobile device 10 returns to step # 1 and continues running (No in # 2). When the current position and direction are corrected (Yes in # 3), it is determined whether or not the user is in a predetermined reconfirmation area (# 3). When it is not in the reconfirmation area, it continues to travel (No in # 4), and when it is in the reconfirmation area (Yes in # 3), it goes to a predetermined reconfirmation point (described later, FIGS. And drive (# 5, # 6). When the position reconfirmation point is reached (Yes in # 6), the second position information acquisition unit acquires the second position information (# 7).

  In the above-described step # 7, when at least the current direction of the autonomous mobile device 10 can be confirmed by the second position information acquisition unit 2 (Yes in # 8), the movement is resumed toward the original destination. (# 11). If the direction cannot be confirmed (No in # 8), it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed (No in # 9), the process returns to Step # 7 and is again performed. The second position information acquisition operation is performed. When the predetermined time has elapsed (Yes in # 9), the autonomous mobile device 10 notifies that it is in an abnormal state by turning on an alarm lamp or generating an alarm sound, for example. (# 10) Returning to step # 7, the second position information acquisition operation is performed again.

  Here, the predetermined time is, for example, 5 minutes, which is sufficient time for the second position information acquisition unit 2 to acquire the second position information. If the direction can be confirmed successfully (Yes in # 8), the movement is resumed toward the original destination (# 11). If a position recognition abnormality alarm is issued when resuming movement, it is canceled. The case where the direction cannot be confirmed is, for example, a case where a moving obstacle passes in front of the autonomous mobile device 10, and the direction can be confirmed when the passage is completed.

  Next, with reference to FIGS. 9 to 11, an example of the position confirmation point determination and the reconfirmation operation in the reconfirmation operation described above will be described. Although the autonomous mobile device 10 shown in these drawings includes two RFID readers 31, the number thereof may be one or many, and the description here is not limited. In FIG. 9, it is assumed that the autonomous mobile device 10 obtains the third position information by reading a plurality of RFID tags 5 arranged on the moving surface. Then, it is assumed that the location where the autonomous mobile device 10 is currently located is a predetermined area for reconfirming the position.

  Near the current position in the above-mentioned predetermined area, for example, there are walls 7, 8, 9 having a structure in which vertical planes are connected, and these walls 7, 8, 9 are the start point and end point of a line representing the wall. Specified by the position coordinates. For example, for the wall 7, the position coordinates of the start point P 1 and the end point P 2 are registered in the environment information map stored in the storage unit 21. The same applies to the other walls 8 and 9. These walls are detected by, for example, the laser range finder described above.

  Since the autonomous mobile device 10 uses such a wall line for its own direction detection, the autonomous mobile device 10 rotates via the control means 4 and the drive wheel 11 so as to face a wall satisfying a predetermined condition, and is predetermined from the wall. It moves to the position of the distance h (this is a reconfirmation point). At this time, a point that can be moved by the shortest distance as described below is selected as a reconfirmation point. In the situation of FIG. 9, first, the control means 4 calculates the distance from the center Q of the autonomous mobile device 10 to the perpendicular foot to the wall. And the leg of each line is not a line extension, but a point on the line, there is no other wall line between the autonomous mobile device 10 and that point, and the shortest point is select. By this process, the movement route indicated by the line segment L1 is selected.

  Next, separately from this, select the end point that is the smallest distance between the end points P1 to P4 of each line and that does not intersect the line of the other wall with the straight line connecting the autonomous mobile device 10 and the end point. To do. Thereby, the movement route indicated by the line segment L2 is selected. Finally, the shorter one of the line segments L1 and L2 is selected, and a point on the line segment and at a predetermined distance h from the wall is set as a reconfirmation point. In the case of FIG. 9, the line segment L2 and the reconfirmation point R are thereby determined. When the reconfirmation point R is determined, the autonomous mobile device 10 moves along the line segment L2, stops at the reconfirmation point, and changes the direction from the original position to that point to the stop direction at that position. (Front direction). By comparing the stop direction with the arrangement direction of the line representing the wall obtained by the above-described wall extraction method, the self direction (posture) can be detected and recognized with high accuracy.

10, autonomous mobile equipment 10 shows a state that has moved to the reconfirmation point R on the aforementioned line L 2. FIG. 11 shows an example in which the autonomous mobile device 10 has moved to the reconfirmation point R selected under a situation different from that in FIG.

  The above-mentioned preset distance h is, for example, a position where a line (wall) including the selected point (perpendicular leg or end point) can be sufficiently detected by the laser range finder, and a person or the like enters the wall. This distance is such that it cannot be detected. Further, if the position and direction of the autonomous mobile device 10 can be corrected by the second position information acquisition unit 2 before reaching the reconfirmation point, the autonomous mobile device 10 heads for the original destination before reaching the reconfirmation point. And move. In addition, when the second position information acquisition unit 2 fails to acquire the direction even after a predetermined time has elapsed after reaching the reconfirmation point, the autonomous mobile device 10 may, for example, Notify by installed display devices such as displays and lamps, and notify of abnormal conditions via wireless communication.

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the sensor of the sensing unit 22 may be configured not only to be provided in front of the autonomous mobile device 10 but also to be attached to the rear or left and right. The antenna 31 that receives information from the outside is not limited to the RFID reader, and may be a GPS antenna. Moreover, it is good also as a structure provided with both of these. When the GPS antenna 31 is used, the GPS antenna 31 is disposed on the top surface, not the bottom surface of the autonomous mobile device 10. In this case, the external information received by the GPS antenna 31 is position information from a GPS satellite. The GPS antenna 31 is preferably provided at a position separated from the rotation center Q of the autonomous mobile device 10 by a predetermined distance. Further, like beacon navigation, for example, a plurality of antennas for transmitting radio waves may be provided on the ground, and position information may be acquired by receiving radio waves from the plurality of antennas.

The block diagram which shows the structure of the autonomous mobile apparatus which concerns on one Embodiment of this invention. The typical top view which shows the movement state and environmental condition of an apparatus same as the above. The top view which shows the relationship of the coordinate in two points when an apparatus same as the above moves between two points. The figure which gathered the intersection of the coordinate axis shown in FIG. 3 in one point, and made it easy to see the relationship of an angle. The typical top view which shows the movement state and environmental condition of the autonomous mobile apparatus which concern on other embodiment of this invention. The top view which shows the relationship of the coordinate in two points when an apparatus same as the above moves between two points. The flowchart which shows the operation | movement at the time of the movement of the autonomous mobile apparatus of this invention. The flowchart which shows the operation | movement when the autonomous mobile apparatus of this invention performs the reconfirmation operation | movement of a position. The top view which shows the mode of reconfirmation operation same as the above. The top view which shows the example of the position confirmation point determination in reconfirmation operation same as the above. The top view which shows the other example of position confirmation point determination in reconfirmation operation same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st positional information acquisition means 2 2nd positional information acquisition means 3 3rd positional information acquisition means 4 Control means 6 Environmental information 10 Autonomous mobile device 21 Memory | storage part 22 Sensing part 31 Antenna

Claims (2)

An autonomous mobile device that moves autonomously,
First position information acquisition means using dead reckoning that acquires the position and direction of the self based on the motion information of the self;
A storage unit that stores an environment information map of a region where the user moves and a sensing unit that acquires environment information, and the surrounding environment information acquired using the sensor of the sensing unit and the environment information map stored in the storage unit A second position information acquisition means for acquiring the position and direction of itself by comparing
A third position information acquisition unit having an antenna for receiving information from the outside, and calculating a position and direction of the self based on information on the plurality of self positions received by the antenna;
Control means for comparing the position and direction of the self acquired by the first, second, and third position information acquisition means to determine the current position and direction of the self,
In the movement of the autonomous mobile device , the control means ,
From the position where the position and direction can be correctly recognized to the position where the second position information acquisition unit acquires the position and direction of the user, the first position information acquisition unit determines the position and direction of the user. Decide
When acquiring the position and direction of the self by the second position information acquisition means, correct the position and direction of the self by the first position information acquisition means by the position and direction,
When the third position information acquisition unit acquires its own position and direction, the position and direction acquired by the first or second position information acquisition unit, the position acquired by the third position information acquisition unit, and when there is a large difference than a predetermined value between a direction, a comparison perilla, autonomous, characterized in that to determine the position and direction the third position information acquisition unit acquires as the position and direction of the current self Mobile device. When the position acquired by the third position information acquisition unit is within a specific region in the moving region where the position and direction can be accurately recognized by the second position information acquisition unit. The autonomous mobile device according to claim 1, wherein a reconfirmation operation is performed to acquire at least the direction of itself by the second position information acquisition unit.

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