JP7243014B2 - moving body - Google Patents

Description

The present disclosure relates to mobile objects.

Research and development of autonomous mobile objects such as automated guided vehicles and mobile robots are underway. If the moving body collides with an obstacle or gets stuck in a ditch while it is moving, the wheels may spin. In that case, normal operation is disturbed, and in the worst case, the floor may be damaged. Therefore, it is important to detect the spinning of the wheels while the moving object is moving.

Conventional methods for detecting slipping of wheels of a moving body are disclosed in Patent Documents 1 to 5, for example. Patent Literature 1 discloses detecting wheel slip based on the difference in the number of rotations of two driving wheels. Patent Literature 2 discloses detecting wheel spin based on the current supplied to a device that drives the wheels. Japanese Patent Laid-Open No. 2002-200003 discloses detecting slipping based on the output of a rotary encoder or the motor torque. Patent Literature 4 discloses detecting wheel spin based on the rotational speeds of left and right driving wheels. Patent Document 5 discloses detecting idle rotation of the drive wheels based on the rotational state of the driven wheels provided separately from the drive wheels.

Japanese Unexamined Patent Application Publication No. 2012-3481 JP 2011-70645 A WO2014/045857 JP-A-10-11140 JP-A-2007-11798

The present disclosure provides a technique for more accurately detecting idle rotation of drive wheels in a moving body that travels without guides.

A moving body in an exemplary embodiment of the present disclosure includes a plurality of drive wheels, a plurality of motors respectively connected to the plurality of drive wheels, and an external sensor that repeatedly scans an environment and outputs sensor data for each scan. a first position estimating 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 a control circuit that controls the plurality of motors. Prepare. The control circuit controls an amount of movement or rotation to be performed by the moving body within a predetermined time period, and an amount of movement or rotation performed by the moving body within the predetermined time period, which is calculated based on the first position information. and/or the time expected to be required to move or rotate a certain amount of the moving body, and the time required for the certain amount of movement or rotation calculated based on the first position information At least one of the plurality of driving wheels is detected based on the difference between .

According to the embodiments of the present disclosure, it is possible to more accurately detect the idle rotation of the driving wheels of a moving body that travels without guides.

FIG. 1 is a block diagram showing a schematic configuration of a mobile 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. 4A is a diagram for explaining still another example of the idling detection process. FIG. 4B is a diagram for explaining still another example of the idling detection process. FIG. 4C is a diagram for explaining still another example of the idling detection process. FIG. 5 is a diagram showing an example of an environment map. FIG. 6 is a diagram showing an example of the distribution of the frequency of occurrence of wheel spins for each area on an environmental map. FIG. 7A is a flow chart showing an example of a wheel rotation detection process. FIG. 7B is a flow chart showing another example of the idling detection process. FIG. 8 is a schematic diagram of a control system that controls travel of each AGV according to the present disclosure. FIG. 9 is a diagram showing an example of a moving space S in which an AGV exists. FIG. 10A is a diagram showing the AGV and towing truck before they are connected. FIG. 10B is a diagram showing a connected AGV and tow truck. FIG. 11 is an external view of an exemplary AGV according to this embodiment. FIG. 12A is a diagram showing a first hardware configuration example of the AGV. FIG. 12B is a diagram showing a second hardware configuration example of the AGV. FIG. 13A is a diagram showing an AGV that generates a map while moving. FIG. 13B is a diagram showing an AGV that generates a map while moving. FIG. 13C is a diagram showing an AGV generating a map while moving. FIG. 13D is a diagram showing an AGV generating a map while moving. FIG. 13E is a diagram showing an AGV generating a map while moving. FIG. 13F is a diagram schematically showing part of the completed map. FIG. 14 is a diagram showing an example in which a map of one floor is composed of a plurality of partial maps. FIG. 15 is a diagram showing a hardware configuration example of an operation management device. FIG. 16 is a diagram schematically showing an example of an AGV movement route determined by the operation management device.

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

"Automated Guided Vehicle" (AGV) means a trackless vehicle that loads cargo manually or automatically into its main body, travels automatically to a designated location, and unloads manually or automatically. "Automated guided vehicle" includes automated towing vehicles and automated forklifts.

The term "unmanned" means that no person is required to steer the vehicle, and does not exclude that the AGV carries "persons (e.g., those loading and unloading goods)".

An “unmanned tractor” is a trackless vehicle that automatically travels to a designated location by towing a trolley that loads and unloads cargo manually or automatically.

An “unmanned forklift” is a trackless vehicle equipped with a mast that raises and lowers a fork for loading and unloading cargo.

A "trackless vehicle" is a vehicle that has wheels and an electric motor or engine that rotates the wheels.

A “moving object” is a device that moves with a person or load on it, and is equipped with a driving device such as wheels, a bipedal or multipedal walking device, or a propeller that generates a driving force (traction) for movement. The term “mobile” in the present disclosure includes mobile robots, service robots, and drones as well as automated guided vehicles in the narrow sense.

"Automatic driving" includes driving based on commands of a computer operation management system to which the automatic guided vehicle is connected by communication, and autonomous driving by a control device provided in the automatic guided vehicle. Autonomous travel includes not only travel by an automatic guided vehicle toward a destination along a predetermined route, but also travel following a tracking target. Also, the automatic guided vehicle may temporarily travel manually based on instructions from the operator. "Automated driving" generally includes both "guided" driving and "guideless" driving, but in this disclosure means "guideless" driving.

The “guide type” is a system in which derivatives are installed continuously or intermittently, and the guides are used to guide an automatic guided vehicle.

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

A "self-position estimation device" is a device that estimates a self-position on an environmental map based on sensor data acquired by an external sensor such as a laser range finder.

The "external sensor" is a sensor that senses the state of the exterior of the moving object. External sensors include, for example, laser range finders (also called range sensors), cameras (or image sensors), LIDAR (Light Detection and Ranging), millimeter wave radars, and magnetic sensors.

An "internal sensor" is a sensor that senses the internal state of a moving object. Internal sensors include, for example, rotary encoders (hereinafter sometimes simply referred to as "encoders"), acceleration sensors, and angular acceleration sensors (eg, gyro sensors).

"SLAM" is an abbreviation for Simultaneous Localization and Mapping, which means performing self-localization and environmental map creation at the same time.

<Embodiment>
In the conventional technology, the presence or absence of slipping is determined based on the rotation of the wheels of the mobile body. However, if the moving body is caught in a groove or the floor is slippery, the drive wheels will continue to rotate, which may prevent accurate detection of idle rotation.

If the driving wheels continue to idle, in the worst case, problems such as scraping of the floor will occur. Therefore, it is not desirable to leave the drive wheels idle. It is desirable to detect the occurrence of slipping at an early stage.

Therefore, in the embodiment of the present disclosure, the motion of the moving object is evaluated from at least one of the following two viewpoints.
・Is the distance that the moving object should travel or the angle that it should rotate within a certain period of time be the same as the distance that it actually traveled or the angle that it rotated?
・Is the expected required time when the moving object moves a certain distance or rotates a certain angle about the same as the actual required time?
If it is determined that they are different from any one of the viewpoints, it is determined that the drive wheels are spinning.

By judging the presence or absence of slipping from the above viewpoint, it is possible to detect slipping more accurately than conventionally.

Hereinafter, embodiments of a mobile body and a mobile system according to the present disclosure will be described with reference to the accompanying drawings. Note that more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity in the following description and to facilitate understanding by those skilled in the art. The inventors provide the accompanying drawings and the following description for a full understanding of the present disclosure by those skilled in the art. They are not intended to limit the claimed subject matter. In the following description, identical or similar components are given the same reference numerals.

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

A plurality of motors 106 are connected to a 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 rotation of the plurality of motors 106 according to instructions from the control circuit 105 . That is, the control circuit 105 controls the plurality of motors 106 via the drive device 107 .

Drive device 107 may include a motor drive circuit, such as an inverter circuit, for each motor 106 . In this embodiment, the drive 107 comprises a second position estimator 109 that produces odometry information. The second position estimating device 109 may be provided independently from the driving device 107 . The second position estimation device 109 may be omitted.

In this embodiment, the number of each of the plurality of drive wheels 111 and the plurality of motors 106 is two. However, the number is not limited to this example, and may be other numbers, such as three or four.

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 an image sensor or other type of sensor such as 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 . The first position estimation device 103 generates the first position information by, for example, referring to the environmental map recorded in the storage device 113 and matching the environmental map with the sensor data. A specific example of this processing will be described later. The first position estimator 103 may be implemented by a circuit including a processor, such as a microcontroller unit (MCU). The first position estimation device 103 may output reliability data indicating the likelihood of the position estimation result in addition to the first position information. The reliability data indicates, for example, the degree of matching between the environmental map and the sensor data.

Second position estimating device 109 acquires the measured value or estimated value of the rotational speed of each of drive wheels 111, and second position information indicating the estimated value of the position and orientation of moving body 10 based on the value. are generated and output sequentially. The second position estimation device 109 may generate odometry information by correcting the second position information as necessary. The second position estimator 109 may be implemented by a circuit including a processor, such as a microcomputer within the drive 107 .

In the example shown in FIG. 1, the mobile body 10 includes a plurality of rotary encoders 108 that measure the rotational speeds of the drive wheels 111, respectively. 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 can repeatedly calculate the displacement vector of the moving body 10 by applying a known formula to the rotational speeds of the drive wheels 111 measured by the rotary encoders 108, for example. Here, the displacement vector means a set of changes in position (x, y) and orientation (θ) per unit time. The displacement vector can be used as second position information. Here, (x, y) are the coordinate values of the reference point of the moving body 10 (for example, the point where the external sensor is located) in the two-dimensional coordinate system fixed to the environment in which the moving body 10 moves. θ represents an angle (counterclockwise is positive) formed by the front direction of the moving body 10 and a reference direction (for example, the x direction). The calculation formula can be, for example, a formula that relates the rotational speed of each drive wheel 111 and the displacement of the moving body 10 when it is assumed that no slip occurs between each drive wheel 111 and the road surface. If the number of rotations of drive wheel 111 per unit time (for example, one second) is n and the diameter of drive wheel 111 is d, πdn can be said to be the amount of movement of drive wheel 111 per unit time. For each of the plurality of drive wheels 111, the amount of movement per unit time is obtained, and from the combination of these amounts of movement, the amount of change in the position (x, y) and attitude (θ) of the moving body 10 within a certain period of time. can be asked for. The second position information may be obtained using a table that defines a similar relationship instead of the calculation formula. Instead of using information from the plurality of rotary encoders 108, the second position estimator 109 or control circuit 105 may estimate the rotation speed of the motor 106 based on current or voltage measurements in each motor drive circuit. .

The control circuit 105 is a circuit that controls the operation of the moving body 10 . Control circuit 105 acquires first position information from first position estimation device 103 and acquires second position information from second position estimation device 109 . The control circuit 105 detects idle rotation of at least one of the drive wheels 111 based on at least one of the following (1) and (2).
(1) The difference between the amount of movement or rotation that the moving body 10 should perform within a certain period of time and the amount of movement or rotation that the moving body 10 has made within the certain period of time, which is calculated based on the first position information. (2) the difference between the time expected to be required for moving or rotating a certain amount of the moving body 10 and the time required for moving or rotating the certain amount calculated based on the first position information;

In this specification, the determination based on the "ratio" is also included in the determination based on the "difference". The amount of movement or rotation that the moving body 10 should perform within a certain period of time can be calculated based on rotational speed command values for the plurality of motors 106 or the acquired second position information. Similarly, the estimated time required for a certain amount of movement or rotation of the mobile body 10 can be calculated based on the rotational speed command values to the plurality of motors 106 or the obtained second position information.

The control circuit 105 determines the amount of movement or rotation that the moving body 10 should perform within a certain period of time and the amount of movement or rotation that the moving body has made within the certain period of time, which is calculated based on the first position information. When the difference is greater than the first threshold, a signal is output indicating that a wheel spin is occurring. Control circuit 105 also determines that the difference between the time expected to be required for a certain amount of movement or rotation and the time required for the certain amount of movement or rotation calculated based on the first position information is a second threshold value. , it outputs a signal indicating that a wheel spin is occurring. These signals may be commands to stop each motor 106, for example. Alternatively, if the moving body 10 has a speaker, the signal may be a command to cause the speaker to emit a warning sound. When the control circuit 105 detects that at least one drive wheel 111 is spinning, the control circuit 105 sends, for example, a stop instruction to each motor 106 to stop the moving body 10 . As a result, it is possible to avoid problems such as damaging the floor when slipping occurs.

The control circuit 105 may cause the moving body 10 to move backward when detecting the slipping, and escape from the place where the slipping occurs. In that case, the control circuit 105 may direct the moving body 10 to the destination along a route that avoids the place where the wheel spin occurred.

When the control circuit 105 detects the slip, it may transmit a signal indicating that the slip is occurring to another device such as the management device 50 via the communication circuit 104 . The other device is not limited to the management device 50, and may be a computer such as a tablet owned by an administrator or a user. Alternatively, the other device may be a device that performs an action to eliminate spinning. Such a device may, for example, perform the action of lifting the housing of the moving body 10 and moving it away from where the slip occurred.

The control circuit 105 can perform the calculation for the above-described idling detection while the moving body 10 is performing an arbitrary operation. For example, when the mobile body 10 is traveling straight, when the mobile body 10 is moving in a curved line, and when the mobile body 10 is turning, an operation for detecting wheel slip can be executed. To facilitate the calculation, the above calculation may be performed while the rotational speed of each of the plurality of drive wheels 111 is maintained at a constant value.

FIG. 2 is a diagram for explaining a method for judging whether or not there is a slip based on the time required to move a certain distance S. FIG. For simplicity, an example in which the moving body 10 moves straight in one direction at a constant speed v will be described. In this case, the predicted value tx of the time required to move the distance S is obtained by calculating tx=S/v. Using this time tx as a reference, a threshold tt is set to tt=tx+Δt. Δt is the margin time. The margin time Δt can be set to a value smaller than tx, such as a value of 5% to 30% of tx. The control circuit 105 can calculate an estimated value of the movement distance from the initial position by temporally integrating the amount of change in coordinates in the first position information repeatedly output during movement. When the estimated travel distance reaches S, the control circuit 105 compares the time required for the travel with a threshold tt. The control circuit 105 determines that the wheel is not spinning when t≦tt, and determines that the wheel is spinning when t>tt.

In this example, when the moving body 10 is moving at high speed, it is possible to detect spinning in a short period of time. Conversely, if the vehicle is moving at a low speed, it may take a long time to detect wheel slip.

Therefore, the control circuit 105 may change the set value of the distance S according to the speed command value of the moving body 10 . For example, the distance S may be set to be proportional to the speed command value. By doing so, even when moving at a low speed, it is possible to shorten the time until the wheel slip is detected.

In the example of FIG. 2, there may be a case where the estimated value of the moving distance does not reach S even if the wheel spin occurs. In order to avoid such a situation, the control circuit 105 may determine that idling occurs when t>tt.

3A and 3B are diagrams for explaining a method for determining whether or not there is an idle rotation based on the distance traveled during the fixed time T. FIG. In this example as well, the moving body 10 is traveling straight in one direction at a constant speed v. In this case, the predicted value sx of the distance traveled during the fixed time T is obtained by calculating sx=v×T. Using this distance sx as a reference, a distance threshold st is set to st=sx−Δs. Δs is the margin distance. The margin distance Δs can be set to a value smaller than sx, for example, a value of about 5% to 30% of Sx. The control circuit 105 can calculate the estimated value s of the distance traveled during the time T by temporally integrating the amount of change in the coordinates in the first position information that is periodically output during movement. The control circuit 105 compares the estimated distance s traveled during the time T with a threshold st. The control circuit 105 determines that idling does not occur when s≧st, and determines that idling occurs when s<st.

In this example, it is possible to determine the presence or absence of idling within a certain time T. Therefore, if the time T is set to a small value, it is possible to detect wheel slip in a short period of time even when the vehicle is moving at a low speed. In this example, the control circuit 105 may change the set value of the time T according to the speed command value of the moving body 10 . For example, the time T may be set to be proportional to the speed command value.

In each example of FIGS. 2 and 3, the moving body 10 moves in a constant direction at a constant speed, but the moving body 10 can also move along a curved trajectory or turn right or left. be. Even in such a case, the above-mentioned slip detection method is effective. This is because the control circuit 105 can estimate the amount of movement from one position to another position from the first position information periodically output from the first position estimation device 103 . Here, the amount of movement used for comparison may be a straight-line distance or a distance along a locus of movement.

The control circuit 105 can perform the idling detection operation at any timing. The control circuit 105 may perform the above-described idling detection operation all the time while the moving body 10 is moving, or may perform it only when the moving body 10 is moving straight ahead, for example.

The idling detection operation can also be performed while the moving body 10 is turning. In the state of turning, the left and right drive wheels 111 have approximately the same number of revolutions and the directions of rotation are opposite to each other. The amount of change in the attitude (θ) is used instead of the coordinates (x, y) for the slip detection during turning.

When the first position estimating device 103 outputs data indicating the reliability of the first position information, the control circuit 105 may perform calculations for wheel slip detection only when the reliability exceeds the threshold. The slip detection in this embodiment is based on the premise that the reliability of the first position information is high. For this reason, it is rational to perform wheel slip detection only when the reliability of the first position information is equal to or higher than a certain value. The reliability can be the ratio of sensor data that can be matched to all sensor data when ICP (Iterative Closest Point) matching is performed between map data and sensor data, for example.

The control circuit 105 may record in the storage device 113 the data indicating the determination result of the presence/absence of slipping in association with the position of the moving body 10 . The control circuit 105 may generate the data for each of a plurality of positions on the travel route of the mobile body 10 and record the data in the storage device 113 in association with the plurality of positions. By performing such recording, it is possible to record an area where idling is likely to occur. When there are a plurality of mobile bodies 10 in the system, the management device 50 may collect data on the position where the slip occurred from each mobile body 10 . As a result, it becomes possible to make adjustments such as determining the route of each moving body 10 by avoiding places where slipping occurs frequently.

Hereinafter, an example of a process of determining whether or not there is a slip using both the first position information and the second position information will be described with reference to FIGS. 4A to 4C. When slipping occurs, it is considered that the difference between the displacement based on the first position information and the displacement based on the second position information is large. Therefore, the presence or absence of slipping can be detected by comparing the difference in displacement with a threshold value. Here, "displacement" means temporal change of coordinates (x, y) and orientation (θ). In the example of Figures 4A-4C, the vehicle 10 has four wheels. Two of them (eg, rear wheels) are drive wheels 111 .

FIG. 4A is a diagram schematically showing a first example of determination processing. In this example, the moving body 10 is moving while drawing a curve to the left. In this state, the right drive wheel 111 is rotating at a higher rotational speed than the left drive wheel 111 .

Let (x(t), y(t), θ(t)) be the position and orientation of the moving body 10 at time t (hereinafter referred to as the “reference position”). The reference position may be, for example, the position indicated by the first position information estimated from the sensor data at time t. Each of first position estimating device 103 and second position estimating device 109 estimates the displacement from the reference position after time Δt has elapsed from time t. The time Δt is longer than the cycle (for example, several tens of milliseconds to several hundred milliseconds) in which the external sensor 101 outputs sensor data. The time Δt may be set to 1 second or more. Let the first position information at time t+Δt be (x1(t+Δt), y1(t+Δt), θ1(t+Δt)). Let the second position information at time t+Δt be (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)). be 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)). be done. Therefore, the difference of these displacements is expressed as (Δx, Δy, Δθ)=(x1(t+Δt)−x2(t+Δt), y1(t+Δt)−y2(t+Δt), θ1(t+Δt)−θ2(t+Δt))). be done.

Now assume that the first location information is approximately accurate. It can be said that the difference (Δx, Δy, Δθ) between the displacement based on the first positional information and the displacement based on the second positional information represents the error of the second positional information. This error can be caused by idling of the drive wheels 111 .

The control circuit 105 calculates this displacement difference vector (.DELTA.x, .DELTA.y, .DELTA..theta.) and estimates the presence or absence or degree of wheel slip based on the calculated value. For example, if the value of the sum of the squares of the displacement difference vectors (Δx) ² +(Δy) ² +(Δθ) ² or the square root thereof is greater than a threshold value, it can be determined that the wheel spin is occurring. Although Δθ is also considered in this example, the degree of wheel slip may be determined based on the value of (Δx) ² +(Δy) ² without considering Δθ.

A similar determination can be made using the displacement ratio (x2(t+Δt)/x1(t+Δt), y2(t+Δt)/y1(t+Δt), θ2(t+Δt)/θ1(t+Δt)) instead of the displacement difference. good. The same applies to other examples below.

The control circuit 105 may calculate the amount of displacement in a certain time T by temporally integrating the displacement differences (Δx, Δy, Δθ). Alternatively, Δt itself may be used as the constant time T.

FIG. 4B is a diagram schematically showing a second example of determination processing. In this example, determination is made when the moving body 10 is traveling straight. In this state, the left drive wheel 111 and the right drive wheel 111 are rotating at the same rotational speed. If the left and right drive wheels 111 have different amounts of wear, they will not travel straight even if they rotate at the same rotational speed.

In this example, the attitude θ1(t+Δt) in the first position information at time t+Δt and the attitude θ2(t+Δt) in the second position information at time t+Δt are both substantially the attitude θ(t) at time t. be equivalent to. Therefore, the change in posture can be ignored. Therefore, the control circuit 105 can calculate the vector (Δx, Δy) indicating the displacement difference of the coordinates, and estimate the presence or absence or degree of wheel slip based on the value. For example, the value of the sum of squares of the displacement difference vectors (Δx) ² +(Δy) ² or its square root is compared with a threshold. The control circuit 105 can determine the presence or absence or degree of wheel slip based on the comparison result.

FIG. 4C is a diagram schematically showing a third example of determination processing. In this example, the idling determination is performed while the moving body 10 is turning. Here, an example in which the moving body 10 is turning to the right will be described. In this state, the left and right driving wheels 111 rotate in opposite directions and rotate at the same number of revolutions per unit time. In this case, the amount of change in 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 control circuit 105 determines whether the drive wheels 111 are spinning based only on the attitude displacement difference Δθ=θ1(t+Δ)−θ2(t+Δt). By integrating Δθ over time, the amount of rotation within a certain period of time can be calculated. The value may be used to determine the above-mentioned slipping.

In this 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. An environment map can be a set of point cloud data acquired by, for example, a laser range finder. The environment map may be a set of line segment data. The control circuit 105 may generate data indicating the displacement difference for each of a plurality of areas in the environment map, associate the data with the plurality of areas, and store the data in the storage device 113 .

FIG. 5 is a diagram showing an example of an environment map. FIG. 6 is a diagram showing an example of dividing an environment map into a plurality of areas. As shown in FIG. 6, the environment map may be managed by dividing it into a plurality of rectangular areas having a certain size, for example. The length of one side of each area can be, for example, on the order of several hundred millimeters to several meters. The control circuit 105 may cause the storage device 113 to store data indicating that a wheel spin has occurred for each of a plurality of areas as shown, together with an identifier indicating the area. The management device 50 may collect such data from multiple mobile units 10 . In FIG. 6, areas are expressed with different densities depending on the frequency of occurrence of wheel slip. A darker area indicates that more slips occurred. By generating such map data in advance, the management device 50 can set a route while avoiding areas where the drive wheels 111 are likely to spin.

FIG. 7A is a flow chart showing another example of the idling detection operation. In this example, first, the first position estimation device 103 periodically acquires sensor data from the external sensor 101 (step S101). Based on this sensor data, the first position estimating device 103 estimates the position of the moving object 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 the estimated value of the rotation speed of the drive wheels and generates second position information (step S103). Note that step S103 may be performed before step S102. Next, the control circuit 105 calculates the difference between the displacement calculated based on the first positional information and the displacement calculated based on the second positional information (step S104). For example, any one of the methods described above can be used as the calculation method. The control circuit 105 determines whether the calculated displacement difference exceeds the first threshold (step S105). If the determination is Yes, the control circuit 105 outputs a signal indicating that the wheel is spinning (step S106). If the determination in step S105 is No, the process returns to step S101 and the above operations are performed again.

FIG. 7B is a flow chart showing still another example of the idling detection operation. In this example, only steps S204 and S205 differ from the operation shown in FIG. 7A. After step S103, the control circuit 105 determines the time required for a certain amount of movement or rotation calculated based on the first position information and the time required for a certain amount of movement or rotation calculated based on the second position information. is calculated (step S204). The control circuit 105 determines whether the calculated displacement difference exceeds the second threshold (step S205). If the determination is Yes, the control circuit 105 outputs a signal indicating that the wheel is spinning (step S106). If the determination in step S105 is No, the process returns to step S101 and the above operations are performed again.

More specific examples of mobile bodies and mobile system will be described below. 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". The AGV is also given the reference number "10" and is written as "AGV10". It should be noted that the following description can be similarly applied to mobile bodies other than AGVs, such as robots or manned vehicles having a plurality of driving wheels, unless contradictory.

(1) Basic Configuration of System FIG. 8 shows an example of the basic configuration 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 operation of the AGV 10 . A terminal device 20 operated by the user 1 is also shown in FIG.

The AGV 10 is an unmanned guided vehicle capable of "guideless" travel that does not require a dielectric such as a magnetic tape for travel. The AGV 10 can estimate its own position and transmit the estimation result to the terminal device 20 and the operation management device 50 . The AGV 10 can automatically travel within the moving space S according to 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 traffic management device 50 can be a desktop PC, a notebook PC, and/or a server computer. The operation management device 50 communicates with each AGV 10 via multiple access points 2 . For example, the operation management device 50 transmits to each AGV 10 the coordinate data of the position to which each AGV 10 should go next. Each AGV 10 periodically transmits data indicating its own position and orientation to the operation management device 50, for example, every 100 milliseconds. When the AGV 10 reaches the instructed position, the operation management device 50 further transmits coordinate data of the position to which the vehicle should go next. The AGV 10 can also travel within the moving space S according to the user's 1 operation input to the terminal device 20 . An example of the terminal device 20 is a tablet computer. Typically, the AGV 10 runs using the terminal device 20 when the map is created, and the AGV 10 runs using the operation control device 50 after the map is created.

FIG. 9 shows an example of a moving space S in which three AGVs 10a, 10b and 10c are present. It is assumed that both AGVs are running in the depth direction in the figure. The AGVs 10a and 10b are in the process of transporting loads placed on the top plate. The AGV 10c is running following the AGV 10b in front. For convenience of explanation, reference numerals 10a, 10b, and 10c are attached in FIG. 9, but are described as "AGV 10" below.

The AGV 10 can also transport a load by using a towing truck connected to itself, in addition to the method of transporting the load placed on the top plate. FIG. 10A shows the AGV 10 and towing truck 5 before being connected. Each leg of the tow truck 5 is provided with a caster. The AGV 10 is mechanically connected with the towing truck 5 . FIG. 10B shows the AGV 10 and tow truck 5 connected. When the AGV 10 travels, the tow truck 5 is towed by the AGV 10. - 特許庁By towing the tow truck 5, the AGV 10 can transport the load placed on the tow truck 5. - 特許庁

The connection method between the AGV 10 and the towing truck 5 is arbitrary. An example is described here. A plate 6 is fixed to the top plate of the AGV 10 . The towing carriage 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 in the guide 7. When the insertion is completed, the AGV 10 causes an electromagnetic locking pin (not shown) to pass through the plate 6 and the guide 7 to apply an electromagnetic lock. As a result, the AGV 10 and the towing truck 5 are physically connected.

Refer to FIG. 8 again. Each AGV 10 and the terminal device 20 are connected, for example, one-to-one, and can perform communication conforming to the Bluetooth (registered trademark) standard. Each AGV 10 and terminal device 20 can also perform Wi-Fi (registered trademark) compliant communication using one or a plurality of access points 2 . A plurality of access points 2 are connected to each other via a switching hub 3, for example. 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 to the terminal device 20 from the access point 2b. 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. FIG. Thereby, bidirectional communication between the AGV 10 and the terminal device 20 is realized. A plurality of access points 2 are also connected to an operation management device 50 via a switching hub 3 . Thereby, two-way communication is also realized between the operation management device 50 and each AGV 10 .

(2) Creation of environment map A map of 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 the output of the laser range finder can be used to create a map.

The AGV 10 transitions to the data acquisition mode by user's operation. In data acquisition mode, the AGV 10 begins acquiring sensor data using the laser range finder. The laser range finder periodically scans the surrounding space S by radiating, for example, an infrared or visible laser beam to the surroundings. The laser beam is reflected by surfaces such as walls, structures such as pillars, and objects 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 position of each reflection point reflects the arrival direction and distance of the reflected light. Data of measurement results is sometimes called "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 movement space S is completed, the sensor data accumulated in the storage device are transmitted to the external device. The external device is, for example, a computer having a signal processor and having a mapping program installed.

A signal processor in the external device superimposes the sensor data obtained for each scan. A map of the space S can be created by repeating the process of superimposition by the signal processor. The external device transmits the created map data to the AGV 10 . The AGV 10 saves the created map data in an internal storage device. The external device may be the operation management device 50 or may be 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 processing processor of the external device described above. When creating a map within the AGV 10, there is no need to transmit the accumulated sensor data to an external device. The data volume of sensor data is generally considered to be large. Since there is no need to transmit sensor data to an external device, occupation of communication lines can be avoided.

It should be noted that the movement within the movement space S for acquiring the sensor data can be realized by the AGV 10 running according to the user's operation. For example, the AGV 10 wirelessly receives a travel command from the user via the terminal device 20 to move in the front, back, left, and right directions. The AGV 10 travels forward, backward, leftward, and rightward in the moving space S according to the travel command to create a map. When the AGV 10 is wired to a control device such as a joystick, the AGV 10 may move forward, backward, left and right in the moving space S according to control signals from the control device to create a map. Sensor data may be acquired by a person pushing a measurement trolley equipped with a laser range finder.

Although a plurality of AGVs 10 are shown in FIGS. 8 and 9, the number of AGVs may be one. When a plurality of AGVs 10 exist, the user 1 can use the terminal device 20 to select one AGV 10 from among 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 this embodiment.
The AGV 10 has two driving wheels 11a and 11b, four casters 11c, 11d, 11e and 11f, a frame 12, a carrier table 13, a travel control device 14, and a laser range finder 15. Two drive wheels 11a and 11b are provided on the right and left sides of the AGV 10, respectively. Four casters 11c, 11d, 11e and 11f are arranged at the four corners of the AGV 10. As shown in FIG. It should be noted that the AGV 10 also has multiple motors connected to the two drive wheels 11a and 11b, but the multiple motors are not shown in FIG . FIG. 11 also shows one drive wheel 11a and two casters 11c and 11e positioned on the right side of the AGV 10 and a caster 11f positioned on the left rear, but the left drive wheel 11b and the left front The caster 11d is hidden behind the frame 12 and is not shown. The four casters 11c, 11d, 11e and 11f are freely swivelable. In the following description, the drive wheels 11a and 11b are also referred to as wheels 11a and 11b, respectively.

AGV 10 further comprises at least one obstacle sensor 19 for detecting obstacles. In the example of FIG. 11, four obstacle sensors 19 are provided at four corners of the frame 12 . The number and arrangement of obstacle sensors 19 may be different from the example of FIG. Obstacle sensor 19 may be, for example, a device capable of distance measurement, such as an infrared sensor, an ultrasonic sensor, or a stereo camera. If the obstacle sensor 19 is an infrared sensor, for example, an infrared ray is emitted at regular intervals and the time taken for the reflected infrared ray to return is measured, thereby detecting an obstacle existing within a certain distance. can be done. When the AGV 10 detects an obstacle on the route based on the signal output from at least one obstacle sensor 19, the AGV 10 may perform an action 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 travel control device 14 transmits and receives data to and from the terminal device 20 described above, and performs preprocessing calculations.

The laser range finder 15 is an optical device that measures the distance to a reflection point by emitting an infrared or visible laser beam 15a and detecting the reflected light of the laser beam 15a. In this embodiment, the laser range finder 15 of the AGV 10 emits a pulsed laser beam in a space within a range of 135 degrees to the left and right (270 degrees in total) with respect to the front of the AGV 10, for example, while changing the direction every 0.25 degrees. 15a and detects the reflected light of each laser beam 15a. As a result, it is possible to obtain data on the distance to the reflection point in the direction determined by the angles of 1081 steps in total, every 0.25 degrees. In this embodiment, the scanning of the surrounding space performed by the laser range finder 15 is substantially parallel to the floor surface and planar (two-dimensional). However, the laser range finder 15 may scan 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 scanning result of the laser range finder 15 . The map may reflect the placement of the walls around the AGV, structures such as pillars, and objects placed on the floor. Map data is stored in a storage device provided in the AGV 10 .

Generally, the position and posture of a moving object are called poses. The position and orientation of a moving object in a two-dimensional plane are represented by position coordinates (x, y) in an XY orthogonal coordinate system and an angle θ with respect to the X axis. The position and orientation of the AGV 10, ie pose (x, y, θ), may hereinafter be simply referred to as "position".

The position of the reflection point as seen from the emission position of the laser beam 15a can be expressed using polar coordinates determined by angles and distances. In this 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 rectangular coordinates and output the same.

Since the structure and operating principle of laser range finders are well known, no further detailed description is provided herein. Examples of objects that can be detected by the laser range finder 15 are people, luggage, shelves, walls.

The laser range finder 15 is an example of an external sensor for sensing the surrounding space and acquiring sensor data. Image sensors and ultrasonic sensors can be considered as other examples of such external sensors.

The traveling control device 14 can estimate its own current position by comparing the measurement result of the laser range finder 15 and the map data it holds. Note that 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. As shown in FIG. FIG. 12A also shows a specific configuration of the travel control device 14. As shown in FIG.

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

The traveling control device 14 has 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, which are measurement results, to the microcomputer 14a, the position estimation device 14e and/or the memory 14b. The microcomputer 14a has functions as the control circuit 105 and the second position estimation device 109 shown in FIG.

The microcomputer 14a is a processor or control circuit (computer) that performs calculations for controlling the entire AGV 10 including the travel control device 14. FIG. The microcomputer 14a is typically 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. This causes each of the motors 16a and 16b to rotate at the desired rotational speed.

One or more control circuits (for example, microcomputers) 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 respectively control the driving of the motors 16a and 16b. These two microcomputers may perform coordinate calculations using encoder information output from encoders 18a and 18b, respectively, to estimate the movement distance of AGV 10 from a given initial position. Also, the two microcomputers may control the motor drive circuits 17a and 17b using the encoder information. In that case, the two microcomputers in the motor drive device 17 function as a "second position estimation device".

The memory 14b is a volatile storage device that stores computer programs 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 non-volatile 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 disc. Further, the storage device 14c may include a head device for writing data to and/or reading data from any recording medium and a control device for the head device.

The storage device 14c stores map data M of the space S in which the vehicle travels, and data R of one or more travel routes (travel route data). The map data M are 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. Although the map data M and the travel route data R are stored in the same storage device 14c in this embodiment, they may be stored in different storage devices.

An example of travel route data R will be described.

If 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. A "marker" indicates a passing position (way 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 markers of one or more intermediate waypoints. When the travel route includes one or more intermediate waypoints, the route from the start marker to the end marker via the travel waypoints in order is defined as the travel route. The data of each marker can include the direction (angle) and travel speed data of the AGV 10 until it moves to the next marker, in addition to the coordinate data of that 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, etc., the data of each marker is the acceleration time required for acceleration to reach the running speed, and / or , data of the deceleration time required for deceleration from the running speed to stop at the position of the next marker.

The movement of the AGV 10 may be controlled by the operation management device 50 (eg, PC and/or server computer) instead of the terminal device 20 . In that case, the operation management device 50 may instruct the AGV 10 to move to the next marker each time the AGV 10 reaches the marker. For example, the AGV 10 receives, from the operation control device 50, the coordinate data of the next target position, or the data of the distance to the target position and the angle to be traveled, 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 by the laser range finder 15 acquired during travel.

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

The position estimation device 14e performs map creation processing and self-position estimation processing during travel. 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 scanning result of the laser range finder 15 with the wider map data M, the self-position (x, y, θ) on the map data M is determined. identify. The position estimator 14e generates "reliability" data representing the extent to which the local map data matches the map data M. FIG. Self-position (x, y, θ) and reliability data 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 the self-position (x, y, θ) and reliability data and display them on a built-in or connected display device.

In this embodiment, the microcomputer 14a and the position estimation device 14e are separate components, but this is just an example. A single chip circuit or a semiconductor integrated circuit capable of independently performing each operation of the microcomputer 14a and the position estimation device 14e may be used. FIG. 12A shows chip circuitry 14g that includes microcomputer 14a and position estimator 14e. An example in which the microcomputer 14a and the position estimation device 14e are provided independently will be described below.

Two motors 16a and 16b are attached to the two wheels 11a and 11b respectively to rotate each wheel. That is, the two wheels 11a and 11b are drive wheels respectively. In this embodiment, motors 16a and 16b drive the right and left wheels of AGV 10, respectively.

The moving body 10 further comprises an encoder unit 18 for measuring 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 rotation at any position of the power transmission mechanism from the motor 16a to the wheels 11a. The second rotary encoder 18b measures rotation at any position of the power transmission mechanism from the motor 16b to the wheels 11b. The encoder unit 18 transmits signals obtained by the rotary encoders 18a and 18b to the microcomputer 14a. The microcomputer 14a may control the movement of the moving body 10 using not only the signal received from the position estimation device 14e but also the signal received from the encoder unit 18. FIG.

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 according to the PWM signal sent 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. As shown in FIG. The second hardware configuration example differs from the first hardware configuration example (FIG. 12A) in that it has a laser positioning system 14h and that the microcomputer 14a is connected to each component on a one-to-one basis. do.

The laser positioning system 14 h has 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, for example, by 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 pose (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 is common to that of FIG. 12A except for the configuration described above with respect to FIG. 12B. Therefore, the description of the common configuration is omitted.

The AGV 10 in embodiments of the present disclosure may include safety sensors, such as bumper switches, not shown. The AGV 10 may be equipped with an inertial measurement device such as a gyro sensor. Using data measured by internal sensors such as the rotary encoders 18a and 18b or an inertial measurement device, it is possible to estimate the movement distance of the AGV 10 and the amount of change in attitude (angle). These range and angle estimates are referred to as odometry data or odometry information and may serve to supplement the position and attitude information obtained by position estimator 14e. The odometry data is used when the position and attitude estimates obtained by the position estimator 14e are not reliable, or when switching maps.

(4) Map data FIGS . 13A to 13F schematically show the AGV 10 moving while acquiring sensor data. The user 1 may manually move the AGV 10 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 12B or the AGV 10 itself on a cart and pushing or pulling the cart by the user 1. .

FIG. 13A shows AGV 10 scanning the surrounding space using laser range finder 15 . A laser beam is emitted at each predetermined step angle to perform scanning. It should be noted that the illustrated scan range is an example schematically shown, and is different from the total scan range of 270 degrees described above.

In each of FIGS. 13A to 13F, the positions of the reflection points of the laser beam are schematically indicated using a plurality of black dots 4 represented by symbols "·". The scanning of the laser beam is performed at short intervals while the position and posture of the laser range finder 15 are changed. Therefore, the actual number of reflection points is much larger than the number of reflection points 4 shown. The position estimating device 14e accumulates the positions of the black spots 4 obtained as the vehicle travels, for example, in the memory 14b. Map data is gradually completed by continuously scanning while the AGV 10 is running. In Figures 13B-13E, only the scan range is shown for simplicity. The scan range is an example, and differs from the total 270 degree example described above.

A map may be created using the microcomputer 14a in the AGV 10 or an external computer based on the sensor data obtained after acquiring the necessary amount of sensor data for creating the map. Alternatively, a map may be created in real time based on sensor data acquired by the AGV 10 while it is moving.

FIG. 13F schematically shows a portion of the completed map 40. FIG. In the map shown in FIG. 13F, free space is partitioned by Point Clouds corresponding to collections of reflection points of laser beams. Another example of a map is an occupancy grid map that distinguishes between space occupied by objects and free space by grid units. The position estimation device 14e accumulates map data (map data M) in the memory 14b or the storage device 14c. Note that the illustrated number or density of black dots is an example.

The map data thus obtained can be shared by multiple AGVs 10 .

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

When the area in which the AGV 10 travels is large, the data amount of the map data M increases. Therefore, there is a possibility that problems such as an increase in map creation time and a long time required for self-position estimation may occur. If such an inconvenience occurs, the map data M may be created and recorded by dividing it into a plurality of partial map data.

FIG. 14 shows an example in which a combination of four pieces of partial map data M1, M2, M3, and M4 covers an entire floor of one factory. In this example, one piece of partial map data covers an area of 50m x 50m. A rectangular overlapping area with a width of 5 m is provided at the boundary between two adjacent maps in each of the X and Y directions. This overlapping area is called a "map switching area". When the AGV 10 traveling while referring to one partial map reaches a map switching area, the AGV 10 switches to traveling while referring to another adjacent partial map. The number of partial maps is not limited to four, and may be set as appropriate according to the area of the floor on which the AGV 10 runs, and the performance of the computer that executes map creation and self-position estimation. The size of the partial map data and the width of the overlapping area are also not limited to the above examples, and may be set arbitrarily.

(5) Configuration Example of Operation Management Device FIG. 15 shows an example of the hardware configuration of the operation management device 50 . The operation management device 50 has 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, memory 52, position DB 53, communication circuit 54, map DB 55, and 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 . The CPU 51 is typically a semiconductor integrated circuit. The CPU 51 functions as the control circuit 105 shown in FIG.

The memory 52 is a volatile storage device that stores computer programs 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 potential destination of each AGV 10 . The position data may be represented by coordinates set virtually within the factory by an administrator, for example. Location data is determined by an administrator.

Communication circuit 54 performs wired communication conforming to the Ethernet (registered trademark) standard, for example. The communication circuit 54 is connected to the access point 2 (FIG. 8 ) 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 also transmits 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 map data of the inside of a factory or the like where the AGV 10 travels. The map may be the same as map 40 (FIG. 13F) or may be different. The data format does not matter as long as the map has a one-to-one correspondence with the position of each AGV 10 . 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 non-volatile semiconductor memory, or may be constructed on a magnetic recording medium typified by a hard disk, or an optical recording medium typified by an optical disc.

The image processing circuit 56 is a circuit that generates image data to be displayed on the monitor 58 . The image processing circuit 56 operates exclusively when the manager operates the operation management device 50 . In this embodiment, a more detailed description is omitted. Note that the monitor 58 may be integrated with the operation management device 50 . Alternatively, the processing of the image processing circuit 56 may be performed by the CPU 51 .

(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 showing an example of the moving route of the AGV 10 determined by the operation management device 50. As shown in FIG.

An overview of the operations of the AGV 10 and the operation management device 50 is as follows. Below is an example in which an AGV 10 is currently at a point (marker) _M1 , passes through several positions, and travels to its final destination, a marker Mn ₊₁ (n: a positive integer equal to or greater than 1). explain. Note that the position DB 53 records coordinate data indicating the respective positions of the marker M ₂ to be passed next to the marker M ₁ , the marker _{M 3 to} be passed next to the marker M 2 , and the like.

The CPU 51 of the operation management device 50 refers to the position DB 53, reads the coordinate data of the marker _M2 , and generates a travel command to direct the vehicle to the marker _M2 . A 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 . In this way, the operation management device 50 can track the position of each AGV 10 . When the CPU 51 determines that the current position of the AGV 10 matches the marker M ₂ , the CPU 51 reads the coordinate data of the marker M ₃ , generates a travel command to move the marker M ₃ , and transmits it to the AGV 10 . That is, when the operation management device 50 determines that the AGV 10 has reached a certain position, it transmits a travel command to direct the AGV 10 to the position to be passed next. This allows the AGV 10 to reach its final destination, marker Mn ₊₁ .

Any of the general or specific aspects described above may be implemented by a system, method, integrated circuit, computer program, or recording medium. Alternatively, it may be implemented by any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

The mobile body and mobile body management system of the present disclosure can be suitably used for moving and transporting goods such as packages, 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 control circuit 106 motor 107 drive device 108 rotary encoder 109 second position estimation device 111 drive wheel 113 storage device

Claims (8)

being mobile,
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 by matching the sensor data with an environment map ;
acquiring a measured value or an estimated value of the rotational speed of each of the plurality of drive wheels, and sequentially generating 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; a second position estimation device that outputs the
a control circuit that controls the plurality of motors;
with
The control circuit is
Based on the second position information, determining the amount of movement or rotation that the moving body should perform within a certain period of time and/or the time expected to be required for the certain amount of movement or rotation;
A difference between an amount of movement or rotation that the moving body should perform within the predetermined time and an amount of movement or rotation performed by the moving body within the predetermined time, which is calculated based on the first position information. , when greater than a first threshold, and/or
A difference between the time expected to be required for the movement or rotation of the fixed amount of the moving object and the time required for the movement or rotation of the fixed amount calculated based on the first position information is a second when greater than the threshold,
detecting that at least one of the plurality of drive wheels is spinning;
Mobile. further comprising a plurality of rotary encoders that respectively measure the rotational speeds of the plurality of drive wheels;
The second position estimation device generates the second position information based on data output from the plurality of rotary encoders.
The moving object according to claim 1 . 3. The moving body according to claim 1 , wherein said control circuit stops said moving body when detecting said spinning. further comprising a communication circuit connected to the control circuit;
When the control circuit detects the slip, it transmits a signal indicating that the slip is occurring to another device via the communication circuit.
The moving body according to any one of claims 1 to 3 . 5. The movement according to any one of claims 1 to 4 , wherein the control circuit performs an operation for detecting the slip while the rotational speed of each of the plurality of drive wheels is maintained at a constant value. body. 6. The moving object according to any one of claims 1 to 5 , wherein said control circuit performs an operation for detecting said slip while said moving object is moving straight or turning. The first position estimation device outputs data indicating reliability of the first position information,
The control circuit performs an operation for detecting the wheel spin only when the reliability exceeds a threshold.
The moving body according to any one of claims 1 to 6 . The moving body according to any one of claims 1 to 7 , wherein said external sensor is a laser range finder.

Images