JP2019175137A - Mobile body and mobile body system - Google Patents

Abstract

To provide a technique for updating a map of a space in which a mobile body moves.SOLUTION: A mobile body (101) that can move autonomously, comprises: a drive device (109) that moves the mobile body; an external field sensor (103) that repeatedly scans a surrounding space and outputs sensor data for each scanning; a position estimation device (105) that verifies sensor data with map data prepared in advance and sequentially outputs position information indicating a position and orientation of the mobile body based on a verification result; and a controller (107) that controls the drive device while referring to the position information output from the position estimation device so as to move the mobile body. The position estimation device outputs reliability indicating a degree of coincidence between the sensor data and the map data. When the reliability falls below a predetermined threshold during traveling, the controller generates partial map data of a moving space using the sensor data, and updates a part of the map data with the partial map data.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a moving body and a moving body system.

  An autonomous mobile robot that autonomously moves in space along a predetermined route has been developed. The autonomous mobile robot senses the surrounding space using an external sensor such as a laser distance sensor, matches the sensing result with a map prepared in advance, and estimates (identifies) its current position and posture. . The autonomous mobile robot can move along the route while controlling its current position and posture.

  Japanese Patent Laying-Open No. 2014-203145 discloses a technique related to updating a map. In this document, the map is not updated when the parameter related to the reliability of its own position is small, and the map information is updated only when the parameter is high. Further, in this document, when the degree of matching in the area where the update is permitted is lower than a predetermined value, data on the map is deleted because there is a high possibility that a moving obstacle exists.

  Japanese Patent Application Laid-Open No. 2004-110802 discloses a technique for updating an obstacle grid that retains the probability of whether there is an obstacle on the floor. In this technology, the obstacle grid is updated when a new landmark is observed.

JP 2014-203145 A JP 2004-110802 A

  One non-limiting exemplary embodiment of the present application provides a technique for updating a map of a space in which a moving object moves.

  The mobile body in the exemplary embodiment of the present disclosure is a mobile body that can move autonomously, and a driving device that moves the mobile body and a sensor that scans the surrounding space repeatedly and scans each sensor. An external sensor that outputs data, a position estimation device that collates the sensor data with map data prepared in advance, and sequentially outputs position information indicating the position and orientation of the moving body based on the collation result; and the position A controller that controls the driving device while moving the moving body with reference to the position information output from the estimation device, and the position estimation device has a degree of coincidence between the sensor data and the map data. When the reliability falls below a predetermined threshold during traveling, the controller is moving using the sensor data. It generates partial map data space, to update some of the map data in the partial map data.

  According to the embodiment of the present disclosure, by updating the map, it is possible to maintain the reliability representing the degree to which the sensor data (or the local map) matches the map when the moving body moves to a certain level or more.

FIG. 1 is a block diagram illustrating a schematic configuration of a moving object according to an exemplary embodiment of the present disclosure. FIG. 2 is a flowchart showing an outline of the operation of the moving object. FIG. 3 is a diagram illustrating an overview of a control system that controls traveling of each AGV according to the present disclosure. FIG. 4 is a diagram illustrating an example of the moving space S where the AGV exists. FIG. 5A is a diagram showing an AGV and a towing cart before being connected. FIG. 5B is a diagram showing connected AGVs and tow trucks. FIG. 6 is an external view of an exemplary AGV according to the present embodiment. FIG. 7A is a diagram illustrating a first hardware configuration example of AGV. FIG. 7B is a diagram illustrating a second hardware configuration example of AGV. FIG. 8A is a diagram illustrating an AGV that generates a map while moving. FIG. 8B is a diagram illustrating an AGV that generates a map while moving. FIG. 8C is a diagram illustrating an AGV that generates a map while moving. FIG. 8D is a diagram illustrating an AGV that generates a map while moving. FIG. 8E is a diagram illustrating an AGV that generates a map while moving. FIG. 8F is a diagram schematically showing a part of the completed map. FIG. 9 is a diagram illustrating an example in which a map of one floor is configured by a plurality of partial maps. FIG. 10 is a diagram illustrating a hardware configuration example of the operation management apparatus. FIG. 11 is a diagram schematically illustrating an example of the movement route of the AGV determined by the operation management device. FIG. 12A is a diagram illustrating an example of a matching result immediately after creating a map. FIG. 12B is a diagram illustrating an example in which the installation object 90 illustrated in FIG. 12A is changed to an installation object 92 over time. FIG. 12C is a diagram exemplarily showing a matching result after the installation object 90 is changed to the installation object 92. FIG. 13A is a diagram showing the traveling AGV 10. FIG. 13B is a diagram illustrating an example in which the reliability is lowered to 58% which is less than the threshold value. FIG. 14 is a diagram illustrating the AGV 10 that travels while acquiring sensor data for updating the map 40. FIG. 15 is a diagram illustrating the map 40 that has been updated to reflect the installation 92.

<Terminology>
Prior to describing embodiments of the present disclosure, definitions of terms used herein will be described.

  An “automated guided vehicle” (AGV) means a trackless vehicle in which a package is loaded manually or automatically in a main body, travels automatically to a designated place, and is unloaded manually or automatically. “Automated guided vehicle” includes automatic guided vehicles and automatic forklifts.

  The term “unmanned” means that no person is required to steer the vehicle, and it does not exclude that the automated guided vehicle transports “person (for example, a person who loads and unloads luggage)”.

  An “unmanned towing vehicle” is a trackless vehicle that automatically pulls a cart that loads and unloads luggage manually or automatically travels to a designated location.

  An “unmanned forklift” is a trackless vehicle that includes a mast that moves up and down a load transfer fork, automatically transfers the load to the fork, etc., automatically travels to a designated location, and performs automatic cargo handling work.

  A “trackless vehicle” is a vehicle that includes wheels and an electric motor or engine that rotates the wheels.

  The “moving body” is a device that carries a person or a load and moves, and includes a driving device such as a wheel, a biped or multi-legged walking device, and a propeller that generate a driving traction for movement. The term “mobile body” in the present disclosure includes not only a narrow automatic guided vehicle but also a mobile robot, a service robot, and a drone.

  The “automatic traveling” includes traveling based on a command of a computer operation management system to which the automatic guided vehicle is connected by communication, and autonomous traveling by a control device included in the automatic guided vehicle. Autonomous traveling includes not only traveling where the automated guided vehicle travels to a destination along a predetermined route, but also traveling following a tracking target. Moreover, the automatic guided vehicle may temporarily perform manual travel based on an instruction from the worker. “Automatic travel” generally includes both “guided” travel and “guideless” travel, but in the present disclosure, it means “guideless” travel.

  The “guide type” is a system in which a derivative is installed continuously or intermittently and the guided vehicle is guided using the derivative.

  The “guideless type” is a method of guiding without installing a derivative. The automatic guided vehicle in the embodiment of the present disclosure includes a self-position estimation device and can travel in a guideless manner.

  The “self-position estimation device” is a device that estimates the self-position on the environment map based on sensor data acquired by an external sensor such as a laser range finder.

  An “external sensor” is a sensor that senses an external state of a moving body. Examples of the external sensor include a laser range finder (also referred to as a range sensor), a camera (or an image sensor), a LIDAR (Light Detection and Ranging), a millimeter wave radar, and a magnetic sensor.

  The “inner world sensor” is a sensor that senses the state inside the moving body. Examples of the internal sensor include a rotary encoder (hereinafter sometimes simply referred to as “encoder”), an acceleration sensor, and an angular acceleration sensor (for example, a gyro sensor).

  “SLAM” is an abbreviation for “Simultaneous Localization and Mapping”, and means that self-location estimation and environmental map creation are performed simultaneously.

<Exemplary Embodiment>
Hereinafter, an example of a moving object and a moving object system according to the present disclosure will be described with reference to the accompanying drawings. A more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure. They are not intended to limit the claimed subject matter.

  The mobile body described in the present disclosure can move autonomously using map data and can update the map data. An example of such a moving body is an automatic guided vehicle (for example, FIG. 6 described later).

  FIG. 1 is a block diagram illustrating a schematic configuration of a moving object according to an exemplary embodiment of the present disclosure. The moving body 101 includes an external sensor 103, a position estimation device 105, a controller 107, and a drive device 109. In some embodiments, the position estimation device 105 and the controller 107 are separate semiconductor integrated circuit chips. However, in other embodiments, the position estimation device 105 and the controller 107 can be a single semiconductor integrated circuit chip.

  The driving device 109 includes a mechanism that moves the moving body 101. The drive device 109 may include, for example, at least one drive electric motor (hereinafter simply referred to as “motor”) and a motor control circuit that controls the motor.

  The external sensor 103 is a sensor that senses the external environment, such as a laser range finder, a camera, a radar, or a LIDAR. The external sensor 103 repeatedly scans the surrounding space within a predetermined angle range and outputs sensor data.

  The position estimation device 105 stores map data in a storage device (not shown). The map data is generated using, for example, sensor data acquired before the moving body 101 starts operating. The sensor data can be acquired while the moving body 101 actually moves in the space.

  The position estimation device 105 collates the sensor data output from the external sensor 103 and the map data, and estimates the position and orientation of the moving object based on the collation result. The position estimation device 105 sequentially outputs information (referred to as “position information” in this specification) indicating the estimated position and orientation of the moving body.

  The controller 107 is, for example, a microcontroller unit (microcomputer) that is a semiconductor integrated circuit. The controller 107 controls the driving device 109 while referring to the position information output from the position estimation device 105 to move the moving body 101.

  In the present embodiment, when the position estimation device 105 collates the sensor data with the map data, the position estimation device 105 outputs a reliability indicating the degree to which the two match. When the reliability falls below a predetermined threshold during traveling, the controller 107 generates partial map data of the moving space using the sensor data, and updates a part of the map data with the partial map data. To do. By updating the data of the map (partial map) around the position where the reliability is lowered, the reliability can be maintained in a relatively high state over the entire traveling space. As a result, the position identification accuracy can be improved or improved.

  FIG. 2 is a flowchart illustrating an outline of the operation of the exemplary moving object 101 of the present disclosure. The process according to the flowchart shows the procedure of the process originally executed by a certain CPU, MPU, or microcontroller. However, FIG. 2 explains the processing of the position estimation device 105 and the controller 107 together for convenience of understanding. The position estimation device 105 and the controller 107 execute each process while exchanging data with each other. Steps S <b> 1 to S <b> 3 are processing of the position estimation device 105.

  In step S <b> 1, the position estimation apparatus 105 receives sensor data output by the external sensor 103 repeatedly scanning the surrounding space and outputting each scan. The position estimation apparatus 105 collates the sensor data with the map data in step S2, generates and outputs position information from the collation result in step S3, and outputs reliability data indicating the degree of matching.

  In step S <b> 4, the controller 107 drives the driving device 109 according to the position information output from the position estimation device 105 to move the moving body 101. Step S4 is a process included for convenience of understanding, and is not essential for the map update process. Therefore, in FIG. 2, step S4 is indicated by a broken line.

  Steps S5 and S6 are processing of the controller 107.

  In step S5, the controller 107 determines whether or not the reliability is less than a predetermined threshold value. If the determination result is No, the process returns to step S1, and the position estimation device 105 continues to acquire and move sensor data. On the other hand, when the determination result is No, the process proceeds to step S6.

  In step S6, the controller 107 generates partial map data of the moving space using the sensor data, and updates a part of the map data so far with the partial map data.

  When the reliability is less than the threshold value, the partial map corresponding to the surrounding environment that is currently moving is updated, so that the position identification accuracy around the position can be maintained in a relatively high state. If the partial map is updated based on the same reference throughout the moving space, the position identification accuracy can be improved or improved as a whole.

  Furthermore, it is also effective to provide a communication function in the mobile body 101 by providing the mobile body 101 with a communication circuit. The communication circuit transmits at least the updated partial map to another mobile unit. This makes it possible to update to the latest map data even if other moving objects are not actually moving in the corresponding locations.

  Hereinafter, a more specific example when the moving body is an automatic guided vehicle will be described. In this specification, the automatic guided vehicle may be described as “AGV” using an abbreviation. Note that the following description can be similarly applied to a mobile body other than the AGV, such as a mobile robot, a drone, or a manned vehicle, as long as there is no contradiction.

  The content related to the disclosure described with reference to FIGS. 1 and 2 will be described in more detail in “(7) Example of operation of AGV” described later.

(1) Basic Configuration of System FIG. 3 shows a basic configuration example of an exemplary mobile management system 100 according to the present disclosure. The mobile management system 100 includes at least one AGV 10 and an operation management device 50 that manages the operation of the AGV 10. FIG. 3 also shows a terminal device 20 operated by the user 1.

  The AGV 10 is an automatic guided vehicle capable of “guideless type” traveling that does not require a derivative such as a magnetic tape for traveling. The AGV 10 can perform self-position estimation and transmit the estimation result to the terminal device 20 and the operation management device 50. The AGV 10 can automatically travel in the moving space S in accordance with a command from the operation management device 50. The AGV 10 is further capable of operating in a “tracking mode” in which it moves following a person or other moving body.

  The operation management device 50 is a computer system that tracks the position of each AGV 10 and manages the running of each AGV 10. The operation management device 50 may be a desktop PC, a notebook PC, and / or a server computer. The operation management device 50 communicates with each AGV 10 via the plurality of access points 2. For example, the operation management apparatus 50 transmits the data of the coordinates of the position where each AGV 10 should go next to each AGV 10. Each AGV 10 transmits data indicating its own position and orientation to the operation management device 50 periodically, for example, every 100 milliseconds. When the AGV 10 arrives at the instructed position, the operation management device 50 transmits data on the coordinates of the position to be further headed. The AGV 10 can travel in the moving space S according to the operation of the user 1 input to the terminal device 20. An example of the terminal device 20 is a tablet computer. Typically, the travel of the AGV 10 using the terminal device 20 is performed at the time of map creation, and the travel of the AGV 10 using the operation management device 50 is performed after the map creation.

  FIG. 4 shows an example of a moving space S in which three AGVs 10a, 10b, and 10c exist. Assume that all AGVs are traveling in the depth direction in the figure. The AGVs 10a and 10b are transporting loads placed on the top board. The AGV 10c travels following the front AGV 10b. For convenience of explanation, reference numerals 10a, 10b, and 10c are assigned in FIG. 4, but are hereinafter referred to as “AGV10”.

  In addition to the method of transporting a load placed on the top board, the AGV 10 can also transport the load using a tow cart connected to itself. FIG. 5A shows the AGV 10 and the towing cart 5 before being connected. A caster is provided on each foot of the traction cart 5. The AGV 10 is mechanically connected to the traction cart 5. FIG. 5B shows the AGV 10 and the traction cart 5 connected. When the AGV 10 travels, the tow cart 5 is pulled by the AGV 10. By pulling the tow cart 5, the AGV 10 can transport the load placed on the tow cart 5.

  The connection method between the AGV 10 and the traction cart 5 is arbitrary. Here, an example will be described. A plate 6 is fixed to the top plate of the AGV 10. The pulling cart 5 is provided with a guide 7 having a slit. The AGV 10 approaches the tow truck 5 and inserts the plate 6 into the slit of the guide 7. When the insertion is completed, the AGV 10 passes an electromagnetic lock pin (not shown) through the plate 6 and the guide 7 and applies an electromagnetic lock. Thereby, AGV10 and tow cart 5 are physically connected.

  Refer to FIG. 3 again. Each AGV 10 and the terminal device 20 can be connected, for example, on a one-to-one basis, and can perform communication based on the Bluetooth (registered trademark) standard. Each AGV 10 and the terminal device 20 can also perform communication based on Wi-Fi (registered trademark) using one or a plurality of access points 2. The plurality of access points 2 are connected to each other via, for example, the switching hub 3. FIG. 3 shows two access points 2a and 2b. The AGV 10 is wirelessly connected to the access point 2a. The terminal device 20 is wirelessly connected to the access point 2b. The data transmitted by the AGV 10 is received by the access point 2a, transferred to the access point 2b via the switching hub 3, and transmitted from the access point 2b to the terminal device 20. The data transmitted by the terminal device 20 is received by the access point 2b, transferred to the access point 2a via the switching hub 3, and transmitted from the access point 2a to the AGV 10. Thereby, bidirectional communication between the AGV 10 and the terminal device 20 is realized. The plurality of access points 2 are also connected to the operation management device 50 via the switching hub 3. Thereby, bidirectional communication is also realized between the operation management device 50 and each AGV 10.

(2) Creation of environmental map A map in the moving space S is created so that the AGV 10 can travel while estimating its own position. The AGV 10 is equipped with a position estimation device and a laser range finder, and a map can be created using the output of the laser range finder.

  The AGV 10 transitions to a data acquisition mode by a user operation. In the data acquisition mode, the AGV 10 starts acquiring sensor data using the laser range finder. The laser range finder periodically scans the surrounding space S by periodically emitting, for example, an infrared or visible laser beam. The laser beam is reflected by the surface of a structure such as a wall or a pillar or an object placed on the floor. The laser range finder receives the reflected light of the laser beam, calculates the distance to each reflection point, and outputs measurement result data indicating the position of each reflection point. The direction and distance of the reflected light are reflected at the position of each reflection point. The measurement result data may be referred to as “measurement data” or “sensor data”.

  The position estimation device accumulates sensor data in a storage device. When the acquisition of the sensor data in the moving space S is completed, the sensor data accumulated in the storage device is transmitted to the external device. The external device is, for example, a computer having a signal processor and having a mapping program installed therein.

  The signal processor of the external device superimposes the sensor data obtained for each scan. A map of the space S can be created by repeatedly performing the process of overlapping by the signal processor. The external device transmits the created map data to the AGV 10. The AGV 10 stores the created map data in an internal storage device. The external device may be the operation management device 50 or another device.

  The AGV 10 may create the map instead of the external device. A circuit such as a microcontroller unit (microcomputer) of the AGV 10 may perform the processing performed by the signal processor of the external device described above. When a map is created in the AGV 10, there is no need to transmit the accumulated sensor data to an external device. The data capacity of sensor data is generally considered large. Since it is not necessary to transmit sensor data to an external device, occupation of the communication line can be avoided.

  The movement in the movement space S for acquiring the sensor data can be realized by the AGV 10 traveling according to the user's operation. For example, the AGV 10 receives a travel command instructing movement in the front, rear, left, and right directions from the user via the terminal device 20 wirelessly. The AGV 10 travels forward, backward, left and right in the moving space S according to the travel command, and creates a map. When the AGV 10 is connected to a steering device such as a joystick by wire, a map may be created by traveling forward and backward and left and right in the moving space S according to a control signal from the steering device. Sensor data may be acquired by a person walking around a measurement carriage equipped with a laser range finder.

  3 and 4 show a plurality of AGVs 10, one AGV may be provided. When there are a plurality of AGVs 10, the user 1 can use the terminal device 20 to select one AGV 10 from the plurality of registered AGVs and create a map of the moving space S.

  After the map is created, each AGV 10 can automatically travel while estimating its own position using the map. A description of the process of estimating the self position will be given later.

(3) Configuration of AGV FIG. 6 is an external view of an exemplary AGV 10 according to the present embodiment. The AGV 10 includes two drive wheels 11 a and 11 b, four casters 11 c, 11 d, 11 e and 11 f, a frame 12, a transport table 13, a travel control device 14, and a laser range finder 15. The two drive wheels 11a and 11b are provided on the right side and the left side of the AGV 10, respectively. The four casters 11c, 11d, 11e, and 11f are arranged at the four corners of the AGV 10. The AGV 10 also has a plurality of motors connected to the two drive wheels 11a and 11b, but the plurality of motors are not shown in FIG. FIG. 6 shows one drive wheel 11a and two casters 11c and 11e located on the right side of the AGV 10, and a caster 11f located on the left rear part. The caster 11d is not clearly shown because it is hidden behind the frame 12. The four casters 11c, 11d, 11e, and 11f can freely turn. In the following description, the drive wheels 11a and the drive wheels 11b are also referred to as wheels 11a and wheels 11b, respectively.

  The AGV 10 further includes at least one obstacle sensor 19 for detecting an obstacle. In the example of FIG. 6, four obstacle sensors 19 are provided at the four corners of the frame 12. The number and arrangement of the obstacle sensors 19 may be different from the example of FIG. The obstacle sensor 19 may be a device capable of measuring a distance, such as an infrared sensor, an ultrasonic sensor, or a stereo camera. When the obstacle sensor 19 is an infrared sensor, for example, an obstacle that exists within a certain distance is detected by emitting infrared rays at regular intervals and measuring the time until the reflected infrared rays return. Can do. When the AGV 10 detects an obstacle on the path based on the signal output from the at least one obstacle sensor 19, the AGV 10 performs an operation to avoid the obstacle.

  The travel control device 14 is a device that controls the operation of the AGV 10, and mainly includes an integrated circuit including a microcomputer (described later), electronic components, and a board on which they are mounted. The traveling control device 14 performs the above-described data transmission / reception with the terminal device 20 and the preprocessing calculation.

  The laser range finder 15 is an optical device that measures the distance to a reflection point by, for example, emitting an infrared or visible laser beam 15a and detecting the reflected light of the laser beam 15a. In the present embodiment, the laser range finder 15 of the AGV 10 is a pulsed laser beam that changes its direction every 0.25 degrees in a space in the range of 135 degrees left and right (total 270 degrees) with respect to the front of the AGV 10, for example. The reflected light of each laser beam 15a is detected. Thereby, data of the distance to the reflection point in the direction determined by the angle corresponding to the total of 1081 steps every 0.25 degrees can be obtained. In the present embodiment, the scan of the surrounding space performed by the laser range finder 15 is substantially parallel to the floor surface and is planar (two-dimensional). However, the laser range finder 15 may perform scanning in the height direction.

  The AGV 10 can create a map of the space S based on the position and orientation (orientation) of the AGV 10 and the scan result of the laser range finder 15. The map may reflect the arrangement of walls, pillars and other structures around the AGV, and objects placed on the floor. The map data is stored in a storage device provided in the AGV 10.

  In general, the position and posture of a moving object are called poses. The position and orientation of the moving body in the two-dimensional plane are expressed by position coordinates (x, y) in the XY orthogonal coordinate system and an angle θ with respect to the X axis. The position and posture of the AGV 10, that is, the pose (x, y, θ) may be simply referred to as “position” hereinafter.

  The position of the reflection point seen from the radiation position of the laser beam 15a can be expressed using polar coordinates determined by the angle and the distance. In the present embodiment, the laser range finder 15 outputs sensor data expressed in polar coordinates. However, the laser range finder 15 may convert the position expressed in polar coordinates into orthogonal coordinates and output the result.

  Since the structure and operating principle of the laser range finder are known, further detailed description is omitted in this specification. Examples of objects that can be detected by the laser range finder 15 are people, luggage, shelves, and walls.

  The laser range finder 15 is an example of an external sensor for sensing the surrounding space and acquiring sensor data. Other examples of such an external sensor include an image sensor and an ultrasonic sensor.

  The traveling control device 14 can estimate the current position of the traveling control device 14 by comparing the measurement result of the laser range finder 15 with the map data held by the traveling control device 14. The stored map data may be map data created by another AGV 10.

  FIG. 7A shows a first hardware configuration example of the AGV 10. FIG. 7A also shows a specific configuration of the travel control device 14.

  The AGV 10 includes a travel control device 14, a laser range finder 15, two motors 16a and 16b, a drive device 17, wheels 11a and 11b, and two rotary encoders 18a and 18b.

  The travel control device 14 includes a microcomputer 14a, a memory 14b, a storage device 14c, a communication circuit 14d, and a position estimation device 14e. The microcomputer 14a, the memory 14b, the storage device 14c, the communication circuit 14d, and the position estimation device 14e are connected by a communication bus 14f and can exchange data with each other. The laser range finder 15 is also connected to the communication bus 14f via a communication interface (not shown), and transmits measurement data as a measurement result to the microcomputer 14a, the position estimation device 14e, and / or the memory 14b.

  The microcomputer 14 a is a processor or a control circuit (computer) that performs an operation for controlling the entire AGV 10 including the travel control device 14. Typically, the microcomputer 14a is a semiconductor integrated circuit. The microcomputer 14a transmits a PWM (Pulse Width Modulation) signal, which is a control signal, to the driving device 17 to control the driving device 17 and adjust the voltage applied to the motor. As a result, each of the motors 16a and 16b rotates at a desired rotation speed.

  One or more control circuits (for example, a microcomputer) for controlling the driving of the left and right motors 16a and 16b may be provided independently of the microcomputer 14a. For example, the motor driving device 17 may include two microcomputers that control the driving of the motors 16a and 16b, respectively. These two microcomputers may perform coordinate calculations using the encoder information output from the encoders 18a and 18b, respectively, and estimate the moving distance of the AGV 10 from a given initial position. The two microcomputers may control the motor drive circuits 17a and 17b using encoder information.

  The memory 14b is a volatile storage device that stores a computer program executed by the microcomputer 14a. The memory 14b can also be used as a work memory when the microcomputer 14a and the position estimation device 14e perform calculations.

  The storage device 14c is a nonvolatile semiconductor memory device. However, the storage device 14c may be a magnetic recording medium typified by a hard disk or an optical recording medium typified by an optical disk. Furthermore, the storage device 14c may include a head device for writing and / or reading data on any recording medium and a control device for the head device.

  The storage device 14c stores map data M of the traveling space S and data (travel route data) R of one or more travel routes. The map data M is created by the AGV 10 operating in the map creation mode and stored in the storage device 14c. The travel route data R is transmitted from the outside after the map data M is created. In the present embodiment, the map data M and the travel route data R are stored in the same storage device 14c, but may be stored in different storage devices.

  An example of the travel route data R will be described.

  When the terminal device 20 is a tablet computer, the AGV 10 receives travel route data R indicating a travel route from the tablet computer. The travel route data R at this time includes marker data indicating the positions of a plurality of markers. “Marker” indicates the passing position (route point) of the traveling AGV 10. The travel route data R includes at least position information of a start marker indicating a travel start position and an end marker indicating a travel end position. The travel route data R may further include position information of one or more intermediate waypoint markers. When the travel route includes one or more intermediate waypoints, a route from the start marker to the end marker via the travel route point in order is defined as the travel route. The data of each marker may include data on the direction (angle) and traveling speed of the AGV 10 until moving to the next marker, in addition to the coordinate data of the marker. When the AGV 10 temporarily stops at the position of each marker and performs self-position estimation and notification to the terminal device 20, the data of each marker includes acceleration time required for acceleration to reach the travel speed, and / or Further, it may include data of deceleration time required for deceleration from the traveling speed until the vehicle stops at the position of the next marker.

  The operation management device 50 (for example, a PC and / or a server computer) instead of the terminal device 20 may control the movement of the AGV 10. In that case, the operation management device 50 may instruct the AGV 10 to move to the next marker every time the AGV 10 reaches the marker. For example, the AGV 10 receives, from the operation management device 50, the coordinate data of the target position to be next, or the data of the distance to the target position and the angle to travel as the travel route data R indicating the travel route.

  The AGV 10 can travel along the stored travel route while estimating its own position using the created map and the sensor data output from the laser range finder 15 acquired during travel.

  The communication circuit 14d is a wireless communication circuit that performs wireless communication based on, for example, Bluetooth (registered trademark) and / or Wi-Fi (registered trademark) standards. Each standard includes a wireless communication standard using a frequency of 2.4 GHz band. For example, in a mode in which the AGV 10 is run to create a map, the communication circuit 14d performs wireless communication based on the Bluetooth (registered trademark) standard and communicates with the terminal device 20 one-on-one.

  The position estimation device 14e performs map creation processing and self-position estimation processing during traveling. The position estimation device 14e creates a map of the moving space S based on the position and orientation of the AGV 10 and the scan result of the laser range finder. During traveling, the position estimation device 14e receives sensor data from the laser range finder 15 and reads map data M stored in the storage device 14c. By matching the local map data (sensor data) created from the scan results of the laser range finder 15 with a wider range of map data M, the self position (x, y, θ) on the map data M can be obtained. Identify. The position estimation device 14e generates “reliability” data representing the degree to which the local map data matches the map data M. Each data of the self position (x, y, θ) and the reliability can be transmitted from the AGV 10 to the terminal device 20 or the operation management device 50. The terminal device 20 or the operation management device 50 can receive each data of its own position (x, y, θ) and reliability and display it on a built-in or connected display device.

  In the present embodiment, the microcomputer 14a and the position estimation device 14e are separate components, but this is an example. It may be a single chip circuit or a semiconductor integrated circuit capable of independently performing the operations of the microcomputer 14a and the position estimation device 14e. FIG. 7A shows a chip circuit 14g including the microcomputer 14a and the position estimation device 14e. Below, the example in which the microcomputer 14a and the position estimation apparatus 14e are provided independently is demonstrated.

  The two motors 16a and 16b are attached to the two wheels 11a and 11b, respectively, and rotate each wheel. That is, the two wheels 11a and 11b are drive wheels, respectively. In the present specification, the motor 16a and the motor 16b are described as being motors that drive the right wheel and the left wheel of the AGV 10, respectively.

  The moving body 10 further includes an encoder unit 18 that measures the rotational positions or rotational speeds of the wheels 11a and 11b. The encoder unit 18 includes a first rotary encoder 18a and a second rotary encoder 18b. The first rotary encoder 18a measures the rotation at any position of the power transmission mechanism from the motor 16a to the wheel 11a. The second rotary encoder 18b measures the rotation at any position of the power transmission mechanism from the motor 16b to the wheel 11b. The encoder unit 18 transmits the signals acquired by the rotary encoders 18a and 18b to the microcomputer 14a. The microcomputer 14a may control the movement of the moving body 10 using the signal received from the encoder unit 18 as well as the signal received from the position estimation device 14e.

  The drive device 17 has motor drive circuits 17a and 17b for adjusting the voltage applied to each of the two motors 16a and 16b. Each of motor drive circuits 17a and 17b includes a so-called inverter circuit. The motor drive circuits 17a and 17b turn on or off the current flowing through each motor by a PWM signal transmitted from the microcomputer 14a or the microcomputer in the motor drive circuit 17a, thereby adjusting the voltage applied to the motor.

  FIG. 7B shows a second hardware configuration example of the AGV 10. The second hardware configuration example is different from the first hardware configuration example (FIG. 7A) in that it has a laser positioning system 14h and that the microcomputer 14a is connected to each component in a one-to-one relationship. To do.

  The laser positioning system 14 h includes a position estimation device 14 e and a laser range finder 15. The position estimation device 14e and the laser range finder 15 are connected by, for example, an Ethernet (registered trademark) cable. Each operation of the position estimation device 14e and the laser range finder 15 is as described above. The laser positioning system 14h outputs information indicating the pause (x, y, θ) of the AGV 10 to the microcomputer 14a.

  The microcomputer 14a has various general purpose I / O interfaces or general purpose input / output ports (not shown). The microcomputer 14a is directly connected to other components in the travel control device 14 such as the communication circuit 14d and the laser positioning system 14h via the general-purpose input / output port.

  The configuration other than the configuration described above with reference to FIG. 7B is the same as the configuration in FIG. Therefore, description of a common structure is abbreviate | omitted.

  AGV10 in embodiment of this indication may be provided with safety sensors, such as a bumper switch which is not illustrated. The AGV 10 may include an inertial measurement device such as a gyro sensor. By using the measurement data obtained by the internal sensors such as the rotary encoders 18a and 18b or the inertial measurement device, the movement distance and the change amount (angle) of the posture of the AGV 10 can be estimated. These estimated values of distance and angle are called odometry data, and can exhibit a function of assisting position and orientation information obtained by the position estimation device 14e.

(4) Map Data FIGS. 8A to 8F schematically show the AGV 10 that moves while acquiring sensor data. The user 1 may move the AGV 10 manually while operating the terminal device 20. Alternatively, the sensor data may be acquired by placing the unit including the traveling control device 14 shown in FIGS. 7A and 7B, or the AGV 10 itself on the carriage and pushing or checking the carriage by the user 1 by hand. .

  FIG. 8A shows an AGV 10 that scans the surrounding space using the laser range finder 15. A laser beam is emitted at every predetermined step angle, and scanning is performed. The illustrated scan range is an example schematically shown, and is different from the above-described scan range of 270 degrees in total.

  In each of FIGS. 8A to 8F, the position of the reflection point of the laser beam is schematically shown using a plurality of black spots 4 represented by the symbol “·”. The laser beam scan is executed in a short cycle while the position and posture of the laser range finder 15 change. For this reason, the actual number of reflection points is much larger than the number of reflection points 4 shown in the figure. The position estimation device 14e accumulates the position of the black spot 4 obtained as the vehicle travels, for example, in the memory 14b. By continuously performing scanning while the AGV 10 is traveling, the map data is gradually completed. 8B to 8E, only the scan range is shown for the sake of simplicity. The scan range is an example, and is different from the above-described example of 270 degrees in total.

  The map may be created using the microcomputer 14a in the AGV 10 or an external computer based on the sensor data after obtaining the amount of sensor data necessary for creating the map. Or you may create a map in real time based on the sensor data which AGV10 which is moving moves.

  FIG. 8F schematically shows a part of the completed map 40. In the map shown in FIG. 8F, the free space is partitioned by a point cloud corresponding to a collection of laser beam reflection points. Another example of the map is an occupied grid map that distinguishes between a space occupied by an object and a free space in units of grids. The position estimation device 14e accumulates map data (map data M) in the memory 14b or the storage device 14c. The number or density of black spots shown in the figure is an example.

  The map data obtained in this way can be shared by a plurality of AGVs 10.

  A typical example of an algorithm in which the AGV 10 estimates its own position based on map data is ICP (Iterative Closest Point) matching. As described above, by matching the local map data (sensor data) created from the scan result of the laser range finder 15 with a wider range of map data M, the self-position (x, y, θ) can be estimated.

  When the area where the AGV 10 travels is wide, the data amount of the map data M increases. For this reason, there is a possibility that inconveniences such as an increase in map creation time or a long time for self-position estimation may occur. If such inconvenience occurs, the map data M may be created and recorded separately for a plurality of partial map data.

  FIG. 9 shows an example in which the entire area of one floor of one factory is covered by a combination of four partial map data M1, M2, M3, and M4. In this example, one partial map data covers an area of 50 m × 50 m. A rectangular overlapping region having a width of 5 m is provided at the boundary between two adjacent maps in each of the X direction and the Y direction. This overlapping area is called a “map switching area”. When the AGV 10 traveling while referring to one partial map reaches the map switching area, the traveling is switched to refer to another adjacent partial map. The number of partial maps is not limited to four, and may be appropriately set according to the area of the floor on which the AGV 10 travels, the performance of the computer that executes map creation and self-location estimation. The size of the partial map data and the width of the overlapping area are not limited to the above example, and may be arbitrarily set.

(5) Configuration Example of Operation Management Device FIG. 10 shows a hardware configuration example of the operation management device 50. The operation management device 50 includes a CPU 51, a memory 52, a position database (position DB) 53, a communication circuit 54, a map database (map DB) 55, and an image processing circuit 56.

  The CPU 51, the memory 52, the position DB 53, the communication circuit 54, the map DB 55, and the image processing circuit 56 are connected by a communication bus 57, and can exchange data with each other.

  The CPU 51 is a signal processing circuit (computer) that controls the operation of the operation management device 50. Typically, the CPU 51 is a semiconductor integrated circuit.

  The memory 52 is a volatile storage device that stores a computer program executed by the CPU 51. The memory 52 can also be used as a work memory when the CPU 51 performs calculations.

  The position DB 53 stores position data indicating each position that can be a destination of each AGV 10. The position data can be represented by coordinates virtually set in the factory by an administrator, for example. The location data is determined by the administrator.

  The communication circuit 54 performs wired communication based on, for example, the Ethernet (registered trademark) standard. The communication circuit 54 is connected to the access point 2 (FIG. 3) by wire, and can communicate with the AGV 10 via the access point 2. The communication circuit 54 receives data to be transmitted to the AGV 10 from the CPU 51 via the bus 57. The communication circuit 54 transmits the data (notification) received from the AGV 10 to the CPU 51 and / or the memory 52 via the bus 57.

  The map DB 55 stores internal map data of a factory or the like where the AGV 10 travels. The map may be the same as or different from the map 40 (FIG. 8F). As long as the map has a one-to-one correspondence with the position of each AGV 10, the format of the data is not limited. For example, the map stored in the map DB 55 may be a map created by CAD.

  The position DB 53 and the map DB 55 may be constructed on a nonvolatile semiconductor memory, or may be constructed on a magnetic recording medium represented by a hard disk or an optical recording medium represented by an optical disk.

  The image processing circuit 56 is a circuit that generates video data to be displayed on the monitor 58. The image processing circuit 56 operates exclusively when the administrator operates the operation management device 50. In the present embodiment, further detailed explanation is omitted. The monitor 59 may be integrated with the operation management device 50. Further, the CPU 51 may perform the processing of the image processing circuit 56.

(6) Operation of Operation Management Device An outline of the operation of the operation management device 50 will be described with reference to FIG. FIG. 11 is a diagram schematically illustrating an example of the movement route of the AGV 10 determined by the operation management device 50.

An outline of operations of the AGV 10 and the operation management device 50 is as follows. In the following, an example will be described in which an AGV 10 is currently at a position M ₁ , passes through several positions, and travels to a final destination position M _{n + 1} (n: a positive integer greater than or equal to 1). . In the position DB 53, coordinate data indicating positions such as a position M ₂ to be passed next to the position M _{1 and} a position M ₃ to be passed next to the position M ₂ are recorded.

CPU51 of traffic control device 50 reads out the coordinate data of the position _{M 2} with reference to the position DB 53, and generates a travel command to direct the position _{M 2.} The communication circuit 54 transmits a travel command to the AGV 10 via the access point 2.

The CPU 51 periodically receives data indicating the current position and orientation from the AGV 10 via the access point 2. Thus, the operation management device 50 can track the position of each AGV 10. CPU51 determines that the current position of the AGV10 matches the position _{M 2,} reads the coordinate data of the position _{M 3,} and transmits the AGV10 generates a travel command to direct the position _{M 3.} In other words, when the operation management device 50 determines that the AGV 10 has reached a certain position, the operation management apparatus 50 transmits a travel command for directing to the position to be passed next. As a result, the AGV ₁₀ can reach the final target position M _{n + 1} . The above-described passing position and target position of the AGV 10 may be referred to as “markers”.

(7) Example of AGV Operation Next, a more specific example of the operation of the AGV 10 will be described.

  Immediately after a new map is created by the procedure shown in FIGS. 8A to 8F, the map correctly reflects the actual environment. Therefore, when the position estimation device 14e performs matching between the map data and the sensor data output from the laser range finder 15, the two match well. At this time, the position estimation device 14e outputs data with relatively high reliability.

  FIG. 12A is an example showing a matching result immediately after creating a map. It is assumed that the AGV 10 moves in the direction (upward) indicated by the white arrow from the lower side of the drawing. The drawing shows the scan range of the laser range finder 15 at about 270 degrees.

  The position estimation device 14 e performs matching between the data of the map 40 and the sensor data output from the laser range finder 15. A thick line 80 schematically shows a location where both are determined to match. As understood from the position of the thick line 80, as a result of matching, it is determined by the position estimation device 14e that a part of the wall surface on the left side and the lower side of the drawing and a part of the surface of the installation object 90 match. The reliability at this time is relatively high, for example, 90 to 95%.

  When time elapses after the map 40 is created, the environment changes, which may cause a difference between the actual environment and the map 40. FIG. 12B shows an example in which the installation object 90 shown in FIG. 12A has changed to an installation object 92 over time. When the installation object 90 is, for example, an assembly of a plurality of luggage, the size or shape of the entire installation object 90 may be changed to the installation object 92 when a part of the luggage is carried out. Due to such a change in the environment, the degree of coincidence between the data of the map 40 and the scan data may be reduced as compared with the past.

  FIG. 12C is an example showing the matching result after the installation object 90 is changed to the installation object 92. As in the previous example, the thick line 80 schematically shows a location where both are determined to match. On the other hand, the thick broken line 82 schematically shows a portion that is the same in the example of FIG. 12A but is different due to the change to the installation object 92. At the location of the thick broken line 82, the map 40 data and the scan data are different. Therefore, the reliability decreases to about 35%. Compared with the example of FIG. 12A, the reliability of the example of FIG. 12C is deteriorated by about 55 to 60%. If the situation in which the map 40 and the environment are different is left unattended, the matching accuracy, that is, the position identification accuracy may be lowered.

  Therefore, the present inventor has considered updating the map 40 when the environment changes. The present inventor considered that whether or not the environment has changed may be determined by using reliability data output from the position estimation device 14e as an index. Details will be described below.

  As a method of updating the map 40 when the reliability output from the position estimation device 14e is significantly reduced, it is conceivable to recreate the entire map 40. However, re-creation of the entire map 40 requires time and effort. Therefore, the map 40 may be partially updated with respect to the position where the reliability is greatly reduced and the surrounding area. Specifically, a threshold may be set for the reliability, and the map 40 may be partially updated when the reliability is less than the threshold. The threshold is held in a register (not shown) of the microcomputer 14a, for example, and the microcomputer 14a determines whether or not to update the map 40 by comparing the reliability with the threshold.

  The threshold value is a value serving as a reference for determining whether to update the map 40. Therefore, for example, it is conceivable to set a design minimum value that is determined to be able to correctly perform position identification as a threshold value. In this specification, this minimum value is referred to as a “minimum limit value”. The minimum value is, for example, 30%. If the reliability is less than the minimum value, it is considered that position identification can no longer be performed correctly.

  As a threshold value, the present inventor further considered another determination method. This is because in the situation where the reliability is close to the minimum value, the position identification accuracy is relatively low, and in some cases, the reliability is less than the minimum value, and there is a possibility that the accuracy of position identification cannot be ensured.

  The present inventor considered not setting a minimum limit value as a threshold value but setting a value higher than the minimum limit value. Specifically, the map 40 may be partially updated when the reliability falls below 60%. That is, it is conceivable to set 60%, which is twice as large as the minimum value, as the threshold value. An example when the threshold is set to 60% will be described with reference to FIGS. 13A and 13B. In FIG. 13A and FIG. 13B, the meaning of the bold line is the same as before.

  FIG. 13A shows the traveling AGV 10. The installation object 90 (FIG. 12A) reflected in the original map 40 has already been changed to the installation object 92. However, the part corresponding to the difference between the installation object 90 and the installation object 92 is not yet included in the scan range of the laser range finder 15 of the AGV 10. Therefore, in the state shown in FIG. 13A, the reliability is 80%. That is, since the current reliability is larger than the threshold value, the map 40 is not updated yet.

  Next, FIG. 13B shows an example in which the reliability is reduced to 58%. A symbol “x” in the drawing indicates a position corresponding to a difference between the installation object 90 and the installation object 92. Since the sensor data and the map 40 do not match at the position, the reliability is lowered. Since the current reliability is less than the threshold, the microcomputer 14a of the AGV 10 starts updating the map 40. The microcomputer 14a starts accumulating sensor data in the storage device 14c.

  For example, the microcomputer 14a can update a part of the map 40 by locally executing the same processing as the processing shown in the procedure of FIGS. 8A to 8F.

  Since a value sufficiently larger than the above-described minimum value is set as the threshold value, the position identification accuracy is still sufficiently high even in the situation of FIG. 13B. That is, the number of sensor data that can be acquired by the laser range finder 15 is sufficient, and the microcomputer 14a can determine the coincidence and difference with the map 40 so far. Sensor data at a location where the difference occurs can be used for updating the map 40.

  FIG. 14 shows the AGV 10 that travels while acquiring sensor data for updating the map 40. The sensor data reflects the boundary of the installation object 92 present at a position different from the boundary of the installation object 90. Using the sensor data stored in the storage device 14c, the microcomputer 14a generates partially updated map data of the space where the AGV 10 has moved. The microcomputer 14a updates the map 40 with the partially updated map data.

  FIG. 15 shows the map 40 that has been updated to reflect the installation 92. The approximate position of the updated partial area is indicated by a broken-line circle. It is understood that the part 90a of the boundary of the installation object 90 is changed to the part 92a of the boundary of the installation object 92 by updating the map 40. The standard for ending the update of the map 40 is, for example, when the reliability when using the updated map exceeds 60%. The update may be performed until the reliability exceeds a value higher than 60%, for example, 80%.

  Note that the processing of the microcomputer 14a described above is represented by the flowchart shown in FIG. Therefore, the re-explanation is omitted.

  The processing for updating a part of the map 40 by setting a threshold value larger than the minimum limit value has been described above. The update of the map 40 may be performed along with the travel of the AGV 10, or may be performed after the AGV 10 travels through and accumulates sensor data. The sensor data used for the update may be sensor data obtained for each scan by the laser range finder 15 or may be sensor data obtained by a plurality of scans.

  In the above description, the “reliability” has been described as a numerical value representing the degree to which sensor data considered as local map data matches the map data. However, other definitions are possible. For example, it is good also as a ratio (ratio) with the number of data on the map 40 matched with respect to the number of sensor data to be used among the sensor data which the laser range finder 15 acquired. The position estimation device 14e does not always use all of the obtained sensor data, but may thin out weak sensor data whose reflection point intensity is less than a certain value. The reliability may be calculated based on data used for actual matching.

  The microcomputer 14a of the AGV 10 can transmit data of at least an updated part map (referred to as “partial update map” for convenience) to the outside via the communication circuit 14d. The transmission target may be all data of the updated map 40.

  The transmitted partial update map may be received by the operation management device 50 and / or another AGV existing in the same space. The operation management device 50 may update the current map stored in the map DB 55 (FIG. 10) with the received partial update map, and then broadcast it to other AGVs. Other AGV microcomputers receive the partially updated map data, and update a part of the stored map data with the received partially updated map data. Either process enables each AGV 10 to perform matching by using the latest map data.

  In the above description, the process of whether to update the map is switched depending on whether the reliability is less than the threshold. Here, the difference between “less than” and “less than” is not essential. One skilled in the art can arbitrarily determine whether to include a threshold.

  The comprehensive or specific aspect described above may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium. Alternatively, the present invention may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

  The exemplary mobile body and mobile system of the present disclosure can be suitably used for moving and transporting goods such as luggage, parts, and finished products in factories, warehouses, construction sites, logistics, hospitals, and the like.

  DESCRIPTION OF SYMBOLS 100 Mobile body management system, 101 Mobile body, 103 External sensor, 105 Position estimation apparatus, 107 Controller, 109 Drive apparatus

Claims (8)

A mobile object that can move autonomously,
A driving device for moving the movable body;
An external sensor that repeatedly scans the surrounding space and outputs sensor data for each scan;
A position estimation device that collates the sensor data with map data prepared in advance, and sequentially outputs position information indicating the position and orientation of the moving body based on the collation result;
A controller for controlling the drive device while referring to the position information output from the position estimation device and moving the movable body;
The position estimation device outputs a reliability indicating the degree of coincidence between the sensor data and the map data,
When the reliability falls below a predetermined threshold during traveling, the controller generates partial map data of a moving space using the sensor data, and a part of the map data is converted to the partial map. A moving object that is updated with data. A storage device;
When the reliability falls below a predetermined threshold during traveling,
The controller is
Start storing the sensor data in the storage device;
The moving body according to claim 1, wherein partial update map data of a moving space is generated using the accumulated sensor data. A communication circuit,
The mobile unit according to claim 1, wherein the controller transmits the partial update map data to the outside via the communication circuit. The reliability is set to a minimum value at which the position estimation device can output position information with accuracy required by design,
The mobile object according to claim 1, wherein the threshold value is larger than the minimum value.   The mobile unit according to claim 4, wherein the communication circuit transmits at least the partial update map data to another mobile unit existing in the space. The map data prepared in advance is data received from an external management device,
The mobile unit according to claim 4, wherein the communication circuit transmits the partial update map data to the operation management device and updates a part of the map data prepared in advance to the partial update map data. A mobile body system comprising a plurality of mobile bodies,
Each moving body is the moving body according to any one of claims 1 to 6,
When one of the plurality of moving bodies transmits the partial update map data,
The controller of another mobile body receives the partial update map data, and updates a part of the stored map data with the received partial update map data. At least one moving object;
An operation management device for distributing map data prepared in advance to the at least one moving body;
With
The at least one moving body is the moving body according to any one of claims 1 to 6,
The said operation management apparatus is a mobile body system which updates a part of said map data prepared beforehand with the said partial update map data received from the said at least 1 mobile body.

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