JP2019175138A - Mobile body and management device - Google Patents

Abstract

To prevent operation from being unstable due to slipping of a wheel.SOLUTION: A mobile body 10 comprises a plurality of driving wheels 111, a plurality of motors 106 connected to the plurality of driving wheels respectively, an external sensor 101, a first position estimation device 103 which sequentially generates and outputs first position information indicating estimation values of a position and posture of the mobile body on the basis of data output from the external sensor, a second position estimation device 109 which acquires a measured value or an estimated value of rotation speed of each driving wheel and sequentially generates and outputs second position information indicating estimation values of a position and posture of the mobile body on the basis of the measured value or the estimated value, and an arithmetic circuit 105 which reduces the rotation speed of the plurality of motors within a predetermined range from a position indicated by the first position information when a difference between deviation of the mobile body calculated based on the first position information and deviation of the mobile body before calculation based on the second position information becomes a threshold or more.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a mobile object and a management apparatus.

  Research and development of autonomously moving mobile objects such as automated guided vehicles or mobile robots are ongoing. In order for the moving body to move autonomously, it is necessary to recognize its own position and posture (hereinafter referred to as “self-position”). The self position can be estimated, for example, by matching environmental map data prepared in advance with data acquired using an external sensor such as a laser range finder. The self-position can also be estimated based on an integrated value of the rotation speed of the wheel (that is, the number of rotations per unit time). The position information estimated by the latter method is referred to as “odometry information”. Odometry information is likely to cause errors due to factors such as wheel slipping or wear.

  International Publication No. 13/002067 discloses an autonomous mobile robot that performs position and orientation estimation using a particle filter. It is disclosed that a position / orientation estimation threshold is obtained by particle dispersion as an amount for determining the position / orientation estimation state, and the mobile robot is decelerated or stopped.

  Japanese Patent Laid-Open No. 2006-004175 discloses that a position is identified more accurately by combining a movement distance measured using a sensor such as an encoder and an identification of a current position by a position identification unit. ing.

International Publication No. 13/002067 JP 2006-004175 A

  The present disclosure provides a technique for suppressing an unstable operation caused by slipping of a wheel in a moving body that performs guideless traveling.

  A moving body in an exemplary embodiment of the present disclosure includes a plurality of driving wheels, a plurality of motors connected to the plurality of driving wheels, and an external sensor that repeatedly scans the environment and outputs sensor data for each scan. A first position estimation device that sequentially generates and outputs first position information indicating estimated values of the position and orientation of the moving body based on the sensor data, and measurement of rotational speeds of the plurality of drive wheels A second position estimation device that obtains a value or an estimated value, and sequentially generates and outputs second position information indicating an estimated value of the position and orientation of the moving body based on the measured value or the estimated value; When a displacement difference, which is a difference between the displacement of the moving body calculated based on one position information and the displacement of the moving body calculated based on the second position information, is equal to or greater than a predetermined threshold, First position Within a predetermined range from the position indicated by the broadcast, and a computing circuit for reducing the rotational speed of the plurality of motors.

  According to the embodiment of the present disclosure, in a moving body that performs guideless traveling, it is possible to suppress an operation from becoming unstable due to slipping of a wheel.

FIG. 1 is a block diagram illustrating a schematic configuration of a moving object 10 according to an exemplary embodiment of the present disclosure. FIG. 2 is a diagram for explaining an example of the idling detection process. FIG. 3 is a diagram for explaining another example of the idling detection process. FIG. 4 is a diagram for explaining still another example of the idling detection process. FIG. 5 is a diagram illustrating an example of an environment map. FIG. 6 is a diagram illustrating an example of the distribution of displacement differences for each area in the environment map. FIG. 7 is a flowchart illustrating an example of the idling detection process. FIG. 8 is a diagram illustrating an overview of a control system that controls traveling of each AGV according to the present disclosure. FIG. 9 is a diagram illustrating an example of the moving space S in which the AGV exists. FIG. 10A is a diagram showing an AGV and a towing cart before being connected. FIG. 10B is a diagram showing the connected AGV and towing cart. FIG. 11 is an external view of an exemplary AGV according to the present embodiment. FIG. 12A is a diagram illustrating a first hardware configuration example of AGV. FIG. 12B is a diagram illustrating a second hardware configuration example of AGV. FIG. 13A is a diagram illustrating an AGV that generates a map while moving. FIG. 13B is a diagram illustrating an AGV that generates a map while moving. FIG. 13C is a diagram illustrating an AGV that generates a map while moving. FIG. 13D is a diagram illustrating an AGV that generates a map while moving. FIG. 13E is a diagram illustrating an AGV that generates a map while moving. FIG. 13F is a diagram schematically illustrating a part of the completed map. FIG. 14 is a diagram illustrating an example in which a map of one floor is configured by a plurality of partial maps. FIG. 15 is a diagram illustrating a hardware configuration example of the operation management apparatus. FIG. 16 is a diagram schematically illustrating an example of the movement route of the AGV determined by the operation management device.

<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.

  A “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, or a propeller that generates 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”, which means that self-location estimation and environmental map creation are performed simultaneously.

<Exemplary Embodiment>
Until now, no effective method for detecting idling of a wheel has been known for a moving body that performs guideless traveling. If the wheel slips, not only the smooth operation of the moving body is hindered, but also undesirable results such as damaging the floor may be caused.

  The present inventor has conceived the configuration of the embodiment of the present disclosure described below in order to suppress the unstable operation caused by slipping of the driving wheel in a moving body that performs guideless traveling.

  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. In the following description, the same or similar components are given the same reference numerals.

  FIG. 1 is a block diagram illustrating a schematic configuration of a moving object 10 according to an exemplary embodiment of the present disclosure. The moving body 10 includes a plurality of driving wheels 111, a plurality of electric motors (hereinafter simply referred to as “motors”) 106, an external sensor 101, a first position estimating device 103, a driving device 107, and an arithmetic circuit 105. A storage device 113 and a communication circuit 104. The drive device 107 includes a second position estimation device 109. FIG. 1 also shows an operation management device 50 (hereinafter also referred to as “management device 50”), which is a device external to the moving body 10.

  The plurality of motors 106 are connected to the plurality of drive wheels 111, respectively. The plurality of motors 106 are driven by the driving device 107 to rotate the plurality of driving wheels 111, respectively. The driving device 107 controls the rotation of the plurality of motors 106 in accordance with instructions from the arithmetic circuit 105.

  The driving device 107 may include a motor driving circuit such as an inverter circuit for each motor 106. In the present embodiment, the driving device 107 includes a second position estimation device 109 that generates odometry information. The second position estimation device 109 may be provided independently from the driving device 107.

  In the present embodiment, the number of each of the plurality of drive wheels 111 and the plurality of motors 106 is two. However, it is not limited to this example, and may be another number, for example, 3 or 4.

  The external sensor 101 sequentially outputs sensor data obtained by repeatedly (for example, periodically) scanning the environment around the moving body 10. A typical example of the external sensor 101 is a laser range finder. The external sensor 101 may be another type of sensor such as an image sensor or an ultrasonic sensor.

  The first position estimation device 103 sequentially outputs first position information indicating estimated values of the position and orientation of the moving body 10 based on the sensor data output from the external sensor 101. For example, the first position estimation device 103 refers to the environment map recorded in the storage device 113 and generates the first position information by matching the environment map with the sensor data. A specific example of this process will be described later. The first position estimation device 103 can be realized by a circuit including a processor, such as a microcontroller unit (microcomputer). In addition to the first position information, the first position estimation device 103 may output reliability data indicating the accuracy of the position estimation result. The reliability data indicates, for example, the degree of coincidence between the environmental map and sensor data.

  Second position estimation device 109 acquires a measured value or an estimated value of the rotational speed of each of the plurality of drive wheels 111, and based on the value, second position information indicating an estimated value of the position and orientation of moving body 10 Are generated and output sequentially. The second position estimation device 109 also generates odometry information obtained by correcting the second position information as necessary. The second position estimating device 109 can be realized by a circuit including a processor such as a microcomputer in the driving device 107, for example.

  In the example illustrated in FIG. 1, the moving body 10 includes a plurality of rotary encoders 108 that respectively measure the rotational speeds of the plurality of drive wheels 111. The second position estimation device 109 can generate second position information based on data output from the plurality of rotary encoders 108. The second position estimation device 109 applies a known calculation formula to the rotational speeds of the plurality of drive wheels 111 measured by the plurality of rotary encoders 108 (that is, the rotational direction and the number of rotations per unit time), for example, Ten displacement vectors are calculated. The displacement vector can be used as the second position information. The calculation formula may be, for example, a formula relating the rotational speed of each driving wheel 111 and the displacement of the moving body 10 when it is assumed that no slip occurs between each driving wheel 111 and the road surface. If the number of rotations per unit time (for example, 1 second) of the drive wheel 111 is n and the diameter of the drive wheel 111 is d, then πdn is the amount of movement of the drive wheel 111 per unit time. For each of the plurality of drive wheels 111, a movement amount per unit time can be obtained, and a change amount of the position (x, y) and posture (θ) of the moving body 10 can be obtained from a combination of the movement amounts. Here, (x, y) is a coordinate value of a reference point (for example, a point where an external sensor is located) of the moving body 10 in a two-dimensional coordinate system fixed in an environment in which the moving body 10 moves. θ represents an angle (a counterclockwise direction is positive) formed by the front direction of the moving body 10 and a reference direction (for example, the x direction). Instead of the calculation formula, the second position information may be obtained using a table that defines the same relationship. The second position estimation device 109 may estimate the rotation speed of the motor 106 based on the measured value of the current or voltage in each motor drive circuit instead of using the information from the plurality of rotary encoders 108.

  The arithmetic circuit 105 is a circuit that controls the operation of the moving body 10. The arithmetic circuit 105 acquires the first position information from the first position estimation device 103 and the second position information from the second position estimation device 109 while the moving body 10 is moving. The arithmetic circuit 105 calculates the displacement (first displacement) of the moving body 10 calculated based on the first position information, and the displacement (second displacement) of the moving body 10 calculated based on the second position information. The degree of slip of the plurality of drive wheels 111 is determined based on the difference between the two (hereinafter, sometimes referred to as “displacement difference”). In this specification, even when the determination is based on the “ratio” between the first displacement and the second displacement, the determination is based on the “difference” between the first displacement and the second displacement. Applicable. The determination of the degree of slip is made based on a comparison result between the displacement difference and a predetermined threshold value. The arithmetic circuit 105 can determine that the driving wheel 111 is slipping when the displacement difference is equal to or greater than a predetermined threshold value. In that case, the arithmetic circuit 105 reduces the rotational speeds of the plurality of motors 106 within a predetermined range from the position indicated by the first position information. Thereby, the mobile body 10 decelerates and is less likely to slip or slip. By appropriately setting the deceleration rate, it is possible to avoid idling of the drive wheels 111 and to continue the movement along the preset route.

  The moving body 10 continues to move in a decelerated state within a predetermined range after starting to decelerate. The predetermined range can be set to a range of about several tens of centimeters to several meters, for example. The arithmetic circuit 105 sets the rotational speed of the motor 106 to a normal value when the displacement difference is below the threshold value or lower than the threshold value after moving a predetermined distance after starting deceleration. You may return. Thereafter, for example, a similar idling detection operation can be performed at regular time intervals.

  The arithmetic circuit 105 may determine a reduction rate (also referred to as “deceleration rate”) of the rotation speeds of the plurality of motors 106 based on a difference between the first displacement and the second displacement. For example, the deceleration rates of the plurality of motors 106 may be increased as the displacement difference is increased. A large displacement difference means that the degree of idling of the drive wheel 111 is large. For this reason, it is reasonable to increase the deceleration rate as the displacement difference increases. The arithmetic circuit 105 may determine the width of the predetermined range in which the low speed operation is continued after deceleration based on the calculated displacement difference. For example, the width of the predetermined range may be increased as the displacement difference is increased.

  The arithmetic circuit 105 may calculate the displacement difference again in a state where the rotation speed is lowered, and may further reduce the rotation speeds of the plurality of motors when the displacement difference does not become less than the threshold value. Such deceleration may be performed a plurality of times, for example, at regular intervals. By decelerating stepwise in this way, it is possible to detect idling while keeping the moving speed relatively high as compared with the case of decelerating suddenly.

  The ease of slipping may vary depending on the position of the floor on which the moving body 10 travels. In that case, it is beneficial to manage the distribution of slipperiness of the floor surface. Accordingly, the arithmetic circuit 105 calculates the displacement difference for each of a plurality of positions on the travel route of the moving body 10 and uses the first position information as data indicating the displacement difference (including data indicating the displacement ratio). May be recorded in the storage device 113 in association with the position indicated by. For example, the arithmetic circuit 105 may generate data indicating a displacement difference for each of a plurality of areas in the environment map, and record the data in the storage device 113 in association with the plurality of areas. By performing such recording, it is possible to record the distribution of the slipperiness of the floor surface when the floor state, the friction coefficient, or the slipperiness varies depending on the position.

  The arithmetic circuit 105 may transmit such data to the external management device 50. In the example illustrated in FIG. 1, the moving body 10 includes a communication circuit 104 connected to an arithmetic circuit 105. The communication circuit 104 performs wireless communication with the management device 50 outside the moving body 10.

  For example, the arithmetic circuit 105 calculates the displacement of the moving body 10 (first displacement) calculated based on the first position information and the displacement of the moving body 10 calculated based on the second position information (second displacement). ) (Displacement difference) may exceed the threshold value, a signal indicating the displacement difference may be transmitted to the management device 50 via the communication circuit 104. Here, “the difference between the first displacement and the second displacement exceeds the threshold” means that the ratio between the first displacement and the second displacement, that is, the magnitude of the first displacement is the second displacement. The ratio divided by the size of is equivalent to being below the threshold. In an example, if the ratio falls below 70%, for example, the signal may be sent to the management device 50. The management device 50 also receives a signal indicating the position from the moving body 10. The management device 50 receives these signals, and can recognize that the drive wheel 111 is slippery at that position. Such a signal may be transmitted to an information terminal held by a user who uses the mobile system, for example. Based on the signal, the user can grasp the position where the drive wheel 111 is slippery.

  When the displacement difference becomes equal to or greater than the threshold value, the arithmetic circuit 105 transmits data indicating the displacement difference and data indicating the position indicated by the first position information to the external management device 50 via the communication circuit 104. Also good. Alternatively, data indicating a displacement difference and data indicating the position may be transmitted to the management device 50 for each of a plurality of positions on the travel route of the moving body.

  The management device 50 may include a communication circuit that receives data indicating a displacement difference and data indicating a position transmitted by the moving body 10 and a processing circuit that performs processing based on the received data. The processing circuit of the management device 50 may generate data indicating the slipperiness distribution of the drive wheels based on the data indicating the displacement difference received from the moving body 10 and the data indicating the position. When a plurality of moving bodies 10 are included in the system, the management apparatus 50 can collect similar data from each moving body 10. In that case, based on the data collected from the plurality of moving bodies 10, data indicating the slipperiness distribution of the drive wheels can be generated.

  The processing circuit of the management device 50 may transmit the data indicating the generated slipperiness distribution to another moving body. Other mobile objects can grasp the slippery location based on the data. Thereby, the other moving body can perform control such as decelerating from the instructed moving speed at a slippery portion. The processing circuit may determine a movement route and / or a movement speed of another moving body based on the generated data indicating the slipperiness distribution, and instruct the other moving body to move. For example, when a slippery place is included on the originally planned route, the route may be changed to a route that avoids the place, and another mobile may be instructed to move. Alternatively, when a slippery place is included on the planned route, another mobile unit may be instructed to decelerate at a predetermined deceleration rate when passing through the place.

  When the system includes a cleaning robot that performs the operation of wiping the floor, the management apparatus 50 may instruct the cleaning robot to wipe a slippery place. In this case, the cleaning robot moves to a designated place and wipes the floor in accordance with an instruction from the management device 50.

  The mobile body 10 can detect idling when the vehicle is traveling straight, moving in a curved line, or turning. Among these, when the rotational speeds of the plurality of drive wheels 111 are the same, the posture of the moving body 10 hardly changes. For this reason, idling can be easily detected without using information on the posture (θ). The turning state is a state in which the rotation speeds of the left and right drive wheels 111 are substantially equal and the rotation directions are opposite to each other. Since the position of the moving body 10 hardly changes during the turning, the change amount of the posture (θ) is used. The idling can be detected at a timing such as turning right or turning left when the moving body 10 is accelerating or decelerating.

  When the first position estimation device 103 outputs data indicating the reliability of the first position information, the arithmetic circuit 105 may perform the idling detection and the speed control only when the reliability exceeds the threshold value. . The idling detection in this embodiment is based on the premise that the reliability of the first position information is high. For this reason, the idling detection may be performed only when the reliability of the first position information is a certain value or more. The reliability may be, for example, a ratio of sensor data that can be matched to the entire sensor data when ICP (Iterative Closest Point) matching is performed between map data and sensor data.

  Hereinafter, an example of the idling detection process will be described with reference to FIGS. In the example of FIGS. 2 to 4, the moving body 10 has four wheels, two of which (rear wheels) are drive wheels 111.

  FIG. 2 is a diagram schematically illustrating a first example of the idling detection process. In this example, the moving body 10 moves while drawing a curve to the left. This state is a state in which the right driving wheel 111 rotates at a higher rotational speed than the left driving wheel 111.

  Here, the position and posture of the moving body 10 at time t (hereinafter referred to as “reference position”) are (x (t), y (t), θ (t)). The reference position may be first position information estimated from sensor data at time t, for example. Each of first position estimation device 103 and second position estimation device 109 estimates a displacement from a reference position after time Δt has elapsed from time t. The time Δt is equal to or longer than the cycle (for example, about several tens of milliseconds to several hundreds of milliseconds) in which the external sensor 101 outputs sensor data. The first position information at time t + Δt is (x1 (t + Δt), y1 (t + Δt), θ1 (t + Δt)). The second position information at time t + Δt is (x2 (t + Δt), y2 (t + Δt), θ2 (t + Δt)).

  The displacement of the moving body 10 calculated based on the first position information is represented by (x1 (t + Δt) −x (t), y1 (t + Δt) −y (t), θ1 (t + Δt) −θ (t)). Is done. The displacement of the moving body 10 calculated based on the second position information is represented by (x2 (t + Δt) −x (t), y2 (t + Δt) −y (t), θ2 (t + Δt) −θ (t)). Is done. Therefore, the difference between these displacements is (Δx, Δy, Δθ) = (x1 (t + Δt) −x2 (t + Δt), y1 (t + Δt) −y2 (t + Δt), θ1 (t + Δt) −θ2 (t + Δt)). Is done.

  Here, it is assumed that the first position information is almost accurate. It can be said that the difference (Δx, Δy, Δθ) between the displacement based on the first position information and the displacement based on the second position information represents an error in the second position information. This error increases as the drive wheel 111 slides greatly.

Therefore, the arithmetic circuit 105 calculates the displacement difference vector (Δx, Δy, Δθ) and estimates the degree of idling based on the calculated value. For example, a table that prescribes the correspondence between the square sum (Δx) ² + (Δy) ² + (Δθ) ^{2 of} the displacement difference vector or the value of the square root thereof and the degree of idling may be prepared in advance. The arithmetic circuit 105 can determine the degree of idling from the sum of squares of the displacement difference vector or the square root value with reference to the table. The arithmetic circuit 105 may evaluate the degree of idling in two stages (present / absent) or may be evaluated in three or more stages (such as none / small / large). When the evaluation is performed in two stages, the arithmetic circuit 105 determines that idling has occurred when the value of the sum of squares of the displacement difference vectors or the square root thereof is equal to or greater than the threshold, and when the value is less than the threshold. Judges that there is no idle rotation. When evaluating in three stages, if the value representing the calculated displacement difference is less than the first threshold value, it is determined that “idle: none”, and the value is greater than or equal to the first threshold value and less than the second threshold value. In some cases, it is determined that “idle: small”, and in the case where the value is greater than or equal to the second threshold and less than the third threshold, it is determined that “idle: large”. In this example, Δθ is also considered, but Δθ may not be taken into account, and the degree of idling may be determined based on the value of (Δx) ² + (Δy) ² .

  Instead of the displacement difference, similar idling detection is performed using displacement ratios (x2 (t + Δt) / x1 (t + Δt), y2 (t + Δt) / y1 (t + Δt), θ2 (t + Δt) / θ1 (t + Δt)). Also good. The same applies to the following other examples.

  FIG. 3 is a diagram schematically illustrating a second example of the idling detection process. In this example, idling detection is performed when the moving body 10 is traveling straight. In this state, the left driving wheel 111 and the right driving wheel 111 are rotating at the same rotational speed. If the wear amounts of the left and right drive wheels 111 are different, they do not go straight even if they rotate at the same rotational speed, but the effect is negligible and ignored.

In this example, the posture θ1 (t + Δt) in the first position information at time t + Δt and the posture θ2 (t + Δt) in the second position information at time t + Δt are both substantially the posture θ (t) at time t. be equivalent to. For this reason, the change in posture can be ignored. Therefore, the arithmetic circuit 105 calculates a vector (Δx, Δy) indicating a coordinate displacement difference, and estimates the degree of idling based on the calculated value. For example, a table that prescribes correspondence between the square sum (Δx) ² + (Δy) ^{2 of} the displacement difference vector or the value of the square root thereof and the degree of idling may be prepared in advance. The arithmetic circuit 105 can determine the degree of idling from the sum of squares of the displacement difference vector or the square root value with reference to the table.

  FIG. 4 is a diagram schematically illustrating a third example of the idling detection process. In this example, idling detection is performed when the mobile body 10 is turning. Here, an example in which the moving body 10 is turning right will be described. In this state, the rotation directions of the left and right drive wheels 111 are opposite to each other, and the rotation speed per unit time is equal. In this case, the change amount of the coordinates (x, y) can be ignored. That is, it can be assumed that x1 (t + Δt) ≈x2 (t + Δt) ≈x (t) and y1 (t + Δt) ≈y2 (t + Δt) ≈y (t). Therefore, the arithmetic circuit 105 may detect the idling of the driving wheel 111 based only on the displacement difference Δθ = θ1 (t + Δ) −θ2 (t + Δt) of the posture.

  In the present embodiment, the storage device 113 stores an environment map. The environment map is data indicating the layout of the environment in which the mobile object 10 moves. The environment map may be a set of point cloud data acquired by a laser range finder, for example. The environment map may be a collection of line segment data. The arithmetic circuit 105 may generate data indicating the displacement difference for each of a plurality of areas in the environment map and store the data in the storage device 113 in association with the plurality of areas.

  FIG. 5 is a diagram illustrating an example of an environment map. FIG. 6 is a diagram illustrating an example in which the environment map is divided into a plurality of areas. As shown in FIG. 6, the environmental map may be managed by being divided into a plurality of rectangular areas having a certain size, for example. The length of one side of each area can be, for example, about several hundred millimeters to several meters. The arithmetic circuit 105 calculates the displacement of the moving body 10 calculated based on the first position information and the displacement (correction) of the moving body 10 calculated based on the second position information for each of a plurality of areas as shown in the figure. A difference from the later displacement may be calculated, and data indicating the difference may be stored in the storage device 113 together with an identifier indicating the area. Note that the method of calculating the corrected displacement difference may be any of the above-described methods, and the same method is used for any area. The displacement difference in each area may be an average value of a plurality of calculated values. In FIG. 6, the areas are expressed with different densities depending on the magnitude of the calculated displacement difference. It can be said that the darker the area, the greater the displacement difference, and the easier or slipping of the drive wheels 111 occurs. By generating such map data in advance, the arithmetic circuit 105 can grasp an area where the driving wheel 111 is likely to slip or slip. By using such map data, the arithmetic circuit 105 can pass at a speed that has been decelerated in advance at a deceleration rate corresponding to the degree of slipperiness when it passes through the slippery area after the next time. Thereby, the movement which suppressed idling of a wheel is attained.

  Map data as shown in FIG. 6 may be managed by the management device 50. In that case, the management device 50 may distribute the map data to each of a plurality of moving objects in the system. Based on the map data, the management device 50 sets the path of each moving body avoiding the slippery area, or decelerates at a deceleration rate corresponding to the slipperiness when passing through the slippery area for each moving body. Can be instructed to do.

  FIG. 7 is a flowchart showing an outline of the operation of the present embodiment. In this example, first, the first position estimation device 103 periodically acquires sensor data from the external sensor 101 (step S101). The first position estimation device 103 estimates the position of the moving body based on the sensor data by the method described above, and generates first position information (step S102). On the other hand, the second position estimating device 109 estimates the position of the moving body 10 based on the measured value or estimated value of the rotational speed of the driving wheel, and generates second position information (step S103). Note that step S103 may be performed before step S102. Next, the arithmetic circuit 105 calculates a difference between the displacement calculated based on the first position information and the displacement calculated based on the second position information (step S104). As the calculation method, for example, any of the methods described above can be used. The arithmetic circuit 105 determines whether the calculated displacement difference is greater than or equal to a threshold value (step S105). If the determination is No, it is determined that no idling has occurred. Therefore, the process returns to step S101 and the movement is continued without reducing the speed. If the determination in step S105 is Yes, it is determined that idling has occurred. For this reason, the arithmetic circuit 105 reduces the rotational speed of the driving wheel (step S106). At this time, the odometry information based on the second position information includes a relatively large error. Therefore, the arithmetic circuit 105 updates the odometry information with the value of the first position information, and returns to step S101. The subsequent second position information is calculated based on the updated odometry information.

  After step S106, while the moving body 10 is located within the predetermined range, the low-speed movement is continued even if it is determined No in the next step S105. The slippery position often extends over a certain area. For this reason, it may be returned to the original speed when it moves a predetermined distance after continuing the low speed operation and the displacement difference falls below another threshold value not more than the above threshold value.

  By the operation as described above, it is possible to avoid the idling by decelerating in an area where the idling of the wheel is likely to occur.

  Hereinafter, more specific examples of the moving body and the moving body system will be described. In the following description, it is assumed that the moving body is an automatic guided vehicle, and the automatic guided vehicle is described as “AGV”. AGV is also denoted by “AGV10” with reference numeral “10”. The following description can be similarly applied to a moving body other than AGV, for example, a robot having a plurality of driving wheels or a manned vehicle, as long as there is no contradiction.

(1) Basic Configuration of System FIG. 8 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. 8 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 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. 9 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. 9, but hereinafter, they are described 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. 10A 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. 10B 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. 8 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. 8 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.

  Although FIG. 8 and FIG. 9 show a plurality of AGVs 10, one AGV may be used. 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. 11 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. Further, FIG. 14 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 portion, but the left drive wheel 11b and the left front portion. 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. 11, 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 an infrared ray every predetermined time and measuring a time until the reflected infrared ray returns. Can do. When the AGV 10 detects an obstacle on the route based on a signal output from the at least one obstacle sensor 19, the AGV 10 may perform 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 transmission / reception of data with the terminal device 20 and the preprocessing calculation described above.

  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. 12A shows a first hardware configuration example of the AGV 10. FIG. 12A 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 14a functions as the arithmetic circuit 105 and the second position estimation device 109 shown in FIG.

  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. In that case, the two microcomputers in the motor drive device 17 function as “second position estimation devices”.

  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. 15A 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 embodiment, the motor 16a and the motor 16b 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. 12B shows a second hardware configuration example of the AGV 10. The second hardware configuration example is different from the first hardware configuration example (FIG. 12A) in that it has a laser positioning system 14 h and the microcomputer 14 a 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. 12B is the same as the configuration in FIG. 12A. 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 measurement data obtained by an internal sensor such as the rotary encoders 18a and 18b or an inertial measurement device, it is possible to estimate the movement distance and the change amount (angle) of the AGV 10. These estimated values of distance and angle are called odometry data or odometry information, and can exhibit a function of assisting position and orientation information obtained by the position estimation device 14e. The odometry data is used when the reliability of the estimated position and orientation values obtained by the position estimation device 14e is low, or when a map switching operation is performed.

(4) Map Data FIGS. 13A to 13F 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 travel control device 14 shown in FIGS. 12A and 6B, or the AGV 10 itself on a cart, and the user 1 manually pushing or driving the cart.

  FIG. 13A 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. 13A to 13F, 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. In FIG. 13B to FIG. 13E, only the scan range is shown for 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. 13F schematically shows a part of the completed map 80. In the map shown in FIG. 13F, a 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. 14 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. 15 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 CPU 51 functions as the first control circuit 51 shown in FIG.

  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. 1) 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 80 (FIG. 13F). 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. 16 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. Hereinafter, an example in which an AGV 10 is currently at a point (marker) M ₁ and passes through several positions and travels to a marker M _{n + 1} (n: a positive integer of 1 or more) which is a final destination. Will be explained. The position DB53 marker M ₂ should pass through the next marker M _{1 is,} the coordinate data indicating the respective positions of the marker M _3, etc. should be passed on to the next marker M ₂ is recorded.

CPU51 of traffic control device 50 reads out the coordinate data of the marker _{M 2} with reference to the position DB 53, and generates a travel command to direct the marker _{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 marker _{M 2,} reads the coordinate data of the marker _{M 3,} and transmits the AGV10 generates a travel command to direct the marker _{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 marker M _{n + 1} that is the final destination.

  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 mobile body and mobile body management 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.

1 User 2a, 2b Access point 10 AGV (mobile)
14 travel control device 14a microcomputer 14b memory 14c storage device 14d communication circuit 14e position estimation device 16a, 16b, 16c, 16d motor 15 laser range finder 17 drive device 17a, 17b, 17c, 17d motor drive circuit 18 encoder unit 18a, 18b, 18c, 18d Rotary encoder 20 Terminal device 50 Operation management device 51 CPU (first control circuit)
52 memory 53 position database (position DB)
54 Communication circuit (first communication circuit)
55 Map database (Map DB)
56 Image Processing Circuit 58 Monitor 101 External Sensor 103 First Position Estimation Device 104 Communication Circuit 105 Arithmetic Circuit 106 Motor 107 Drive Device 108 Rotary Encoder 109 Second Position Estimation Device 111 Drive Wheel 113 Storage Device

Claims (13)

A moving object,
A plurality of drive wheels;
A plurality of motors respectively connected to the plurality of drive wheels;
An external sensor that repeatedly scans the environment and outputs sensor data for each scan;
A first position estimation device that sequentially generates and outputs first position information indicating estimated values of the position and orientation of the moving body based on the sensor data;
A measured value or an estimated value of the rotational speed of each of the plurality of drive wheels is acquired, and second position information indicating an estimated value of the position and orientation of the moving body is sequentially generated based on the measured value or the estimated value. A second position estimation device that outputs
When a displacement difference that is a difference between the displacement of the moving body calculated based on the first position information and the displacement of the moving body calculated based on the second position information is equal to or greater than a predetermined threshold. An arithmetic circuit that reduces the rotational speed of the plurality of motors within a predetermined range from the position indicated by the first position information;
A moving object comprising:   The moving body according to claim 1, wherein the arithmetic circuit increases a rate of decrease in rotational speed of the plurality of motors as the displacement difference increases.   The moving body according to claim 1, wherein the arithmetic circuit increases the width of the predetermined range as the displacement difference increases.   The movement according to any one of claims 1 to 3, wherein the arithmetic circuit further reduces the rotation speeds of the plurality of motors when the displacement difference does not become less than the threshold value in a state where the rotation speed is reduced. body.   The arithmetic circuit calculates the displacement difference for each of a plurality of positions on the travel route of the moving body, and records data indicating the displacement difference in a storage device in association with the position indicated by the first position information. The moving body according to any one of claims 1 to 4. Further comprising the storage device;
The storage device stores an environmental map,
The arithmetic circuit is:
Generating data indicating the displacement difference for each of a plurality of areas in the environmental map, and associating the data with the plurality of areas and recording the data in the storage device;
The moving body according to claim 5. A plurality of rotary encoders for measuring rotational speeds of the plurality of drive wheels, respectively;
The second position estimating device generates the second position information based on data output from the plurality of rotary encoders;
The moving body according to claim 1. The external sensor is a laser range finder,
The first position estimation device generates the first position information by performing matching between the sensor data and an environmental map.
The moving body according to claim 1. A communication circuit connected to the arithmetic circuit;
When the displacement difference is equal to or greater than the threshold, the arithmetic circuit sends data indicating the displacement difference and data indicating the position indicated by the first position information to an external management device via the communication circuit. The mobile body according to claim 1, which transmits.   The arithmetic circuit transmits data indicating the displacement difference and data indicating the position to the management device via the communication circuit for each of a plurality of positions on a travel route of the moving body. The moving body according to 9.   The data indicating the displacement difference and the data indicating the position transmitted by the moving body according to claim 9 or 10 are received, and the slip of the drive wheel is determined based on the data indicating the displacement difference and the data indicating the position. A management apparatus including a processing circuit that generates data indicating the distribution of ease.   The management apparatus according to claim 11, wherein the processing circuit transmits data indicating the slipperiness distribution to another mobile body.   The processing circuit determines a moving path and / or moving speed of another moving body based on the data indicating the slipperiness distribution, and determines the moving path and / or the moving speed for the other moving body. The management apparatus according to claim 11 or 12, which instructs movement.

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