Autonomous driving system, autonomous driving method, and autonomous driving program

Abstract

To provide an autonomous traveling system, an autonomous traveling method, and an autonomous traveling program capable of improving estimation accuracy of a self-position of a traveling device.SOLUTION: An autonomous traveling system 10 includes a reflection device 2 that is disposed at a preset position in a traveling area and reflects emitted light, and an autonomous traveling robot 1 that includes a lidar sensor 14 that emits laser light and receives reflected light of the laser light reflected by the reflection device 2, and that travels while estimating a self-position based on the reflected light. When receiving the laser light emitted from the LiDAR sensor 14, the reflection device 2 changes the intensity of the reflected light. The autonomous traveling robot 1 estimates its own position based on the position of the reflection device 2 in the traveling area specified based on the change in the intensity of the reflected light, and travels.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an autonomous driving system, an autonomous driving method, and an autonomous driving program. [Background technology]

[0002] Conventionally, there are known autonomous traveling devices (autonomous traveling robots, AGVs, etc.) that travel along a predetermined route while estimating their own position. For example, there is known a traveling device that travels along a route by reflecting laser light off a reflector placed near the traveling route and receiving the reflected light, thereby detecting its own position from the receiving angles of the multiple reflected lights (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-283821 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional traveling devices travel while estimating their own position by matching the positions of obstacles measured by sensors (such as lidar sensors) mounted on the traveling device with the positions of obstacles on a pre-created map. For example, the traveling device may deviate from the original target route due to factors such as discrepancies in the rotational speed of the left and right drive wheels, slippage of the drive wheels, and lateral deviation during turns. In such cases, the traveling device corrects its own position so that the measured positions of the obstacles match the positions of the obstacles on the map.

[0005] In such conventional methods, for example, in situations where it is difficult to recognize obstacles (walls, pillars, etc.) that can be used to correct the self-position, it becomes difficult to correct the self-position, resulting in a problem of reduced accuracy in estimating the self-position.

[0006] An object of the present disclosure is to provide an autonomous driving system, an autonomous driving method, and an autonomous driving program that can improve the accuracy of estimating the self-position of a traveling device. [Means for solving the problem]

[0007] An autonomous driving system according to one aspect of the present disclosure includes a reflector disposed at a predetermined position in a driving area and reflecting an irradiated laser beam, and a driving device including a sensor that emits the laser beam and receives the light reflected by the reflector, the driving device estimating its own position based on the reflected light. When the reflector receives the laser beam emitted from the sensor, it changes the intensity of the reflected light. The driving device estimates its own position based on the position of the reflector within the driving area, which is determined based on the change in the intensity of the reflected light.

[0008] An autonomous driving method according to another aspect of the present disclosure is a method for autonomously driving a traveling device that includes a sensor that emits laser light and receives light reflected from a reflector disposed at a predetermined position in a traveling area, and that estimates its own position based on the reflected light. The reflector changes the intensity of the reflected light when it receives the laser light emitted from the sensor. The traveling device estimates its own position based on the position of the reflector within the traveling area, which is determined based on the change in the intensity of the reflected light.

[0009] According to another aspect of the present disclosure, there is provided an autonomous driving program for causing a traveling device, which includes a sensor that emits laser light and receives light reflected from a reflector disposed at a predetermined position in a traveling area, to estimate its own position based on the reflected light and to travel autonomously. The autonomous driving program causes the reflector to change the intensity of the reflected light when the reflector receives the laser light emitted from the sensor, and causes the traveling device to estimate its own position based on the position of the reflector within the traveling area that is determined based on the change in the intensity of the reflected light. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide an autonomous driving system, an autonomous driving method, and an autonomous driving program that can improve the accuracy of estimating the self-position of a traveling device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the overall configuration of an autonomous driving system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view showing the appearance of the autonomous mobile robot according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is an external view showing a state in which a cart is connected to an autonomous mobile robot according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating an example of a map corresponding to a travel area according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating a state in which an autonomous mobile robot irradiates laser light in a travel area according to an embodiment of the present disclosure. [Figure 6A] FIG. 6A is a diagram illustrating an example of the operation of a reflecting device according to an embodiment of the present disclosure. [Figure 6B] FIG. 6B is a diagram illustrating an example of the operation of the reflecting device according to an embodiment of the present disclosure. [Figure 7A]FIG. 7A is a graph showing changes in the intensity of reflected light received by a LIDAR sensor according to an embodiment of the present disclosure. [Figure 7B] FIG. 7B is a graph showing changes in the intensity of reflected light received by the LIDAR sensor according to the embodiment of the present disclosure. [Figure 8A] FIG. 8A is a diagram illustrating an example of distance measurement points on a pillar using laser light according to an embodiment of the present disclosure. [Figure 8B] FIG. 8B is a diagram illustrating an example of a method for self-localization according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a flowchart illustrating an example of a procedure of an autonomous driving process executed in an autonomous driving system according to an embodiment of the present disclosure. [Figure 10A] FIG. 10A is a diagram illustrating an example of the operation of a reflecting device according to an embodiment of the present disclosure. [Figure 10B] FIG. 10B is a diagram illustrating an example of the operation of the reflecting device according to an embodiment of the present disclosure. [Figure 11A] FIG. 11A is a graph showing changes in the intensity of reflected light received by a lidar sensor according to an embodiment of the present disclosure. [Figure 11B] FIG. 11B is a graph showing changes in the intensity of reflected light received by the LIDAR sensor according to the embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram illustrating an example of an operating cycle of a reflecting device according to an embodiment of the present disclosure. [Figure 13] FIG. 13 is a diagram illustrating an example of a method for self-localization using reflecting devices with different operating cycles according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the following embodiments are examples that embody the present disclosure and do not limit the technical scope of the present disclosure.

[0013] FIG. 1 is a block diagram showing the configuration of an autonomous driving system 10 according to an embodiment of the present disclosure. The autonomous driving system 10 includes an autonomous driving robot 1 and a reflecting device 2. The autonomous driving system 10 is a system that uses the reflecting device 2 to cause the autonomous driving robot 1 to autonomously drive. The autonomous driving robot 1 is an autonomously driving type mobile body (also called an AGV, or automated guided vehicle) that travels along a predetermined route while estimating its own position. The reflecting device 2 is installed on obstacles such as pillars and walls within the driving area of ​​the autonomous driving robot 1, such as a warehouse or factory.

[0014] The autonomous driving system 10 may include a management server that manages the operation of one or more autonomous driving robots 1. The management server, for example, sets a driving route for each autonomous driving robot 1 and transmits driving instructions including route data of the driving route to each autonomous driving robot 1.

[0015] [Reflector 2] The reflecting device 2 includes a control unit 21, a storage unit 22, a base unit 23, and a reflector 24. The reflecting device 2 may also include a communication function that enables communication with a management server. The reflecting device 2 is configured to change the intensity of the light reflected from the LIDAR sensor 14 when it receives laser light emitted from the LIDAR sensor 14.

[0016] The base 23 is a fixed member that is fixed to an obstacle such as a pillar or wall inside a warehouse. The reflector 24 is a retroreflective member that has a reflective material (such as aluminum) on its surface and reflects incident laser light back in the incident direction.

[0017] The reflector 24 is connected to the base unit 23 so that its posture can be changed, and changes its posture according to instructions from the control unit 21. For example, the reflector 24 may be movable in parallel in the vertical direction relative to the pillar A1 on the base unit 23 fixed to the pillar A1 (see FIGS. 6A and 6B), or may be rotatable or rotatable in the vertical direction relative to the pillar A1, or may be swingable around an axis (see FIGS. 10A and 10B). Although not shown, the base unit 23 and the reflector 24 are provided with a drive mechanism, and the drive mechanism is communicably connected to the control unit 21.

[0018] The storage unit 22 is a non-volatile storage unit such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash memory that stores various types of information. The storage unit 22 stores a control program for causing the control unit 21 to execute various processes. For example, the control program is non-temporarily recorded on a computer-readable recording medium such as a CD or a DVD, and is read by a reading device (not shown) provided in or connected to the reflection device 2 and stored in the storage unit 22.

[0019] The storage unit 22 also stores information about the period for changing the posture of the reflector 24. For example, in the case where the reflector 24 is configured to translate vertically between a first position and a second position (see FIGS. 6A and 6B), information about the period T for alternately moving the reflector 24 between the first position and the second position is stored in advance in the storage unit 22.

[0020] The control unit 21 has control devices such as a CPU, a ROM, and a RAM. The CPU is a processor that executes various types of arithmetic processing. The ROM is a non-volatile storage unit in which control programs such as a BIOS and an OS that cause the CPU to execute various types of arithmetic processing are stored in advance. The RAM is a volatile or non-volatile storage unit that stores various types of information and is used as a temporary storage memory (work area) for the various types of processing executed by the CPU. The control unit 21 controls the reflection device 2 by having the CPU execute various control programs that are stored in advance in the ROM or the storage unit 22. The control unit 21 may also be composed of one or more electronic circuits.

[0021] Specifically, the control unit 21 changes the attitude of the reflector 24 based on information about the period T stored in the storage unit 22. For example, in the case of a configuration in which the reflector 24 moves parallel to the up and down direction (see FIGS. 6A and 6B) ("first configuration"), the control unit 21 alternately moves the reflector 24 between a first position that coincides with the scanning height of the laser light L1 emitted from the LIDAR sensor 14 and a second position that differs from the scanning height of the laser light L1, at a predetermined period T. In other words, the control unit 21 alternately moves the reflector 24 between an irradiation position (first position) where the laser light L1 is irradiated and a non-irradiation position (second position) where the laser light L1 is not irradiated, at a predetermined period T.

[0022] In this way, the reflecting device 2 is provided with a reflecting plate 24 whose attitude can be changed, and is configured to change the intensity of the laser light incident from the LIDAR sensor 14 by changing the attitude of the reflecting plate 24. Specifically, the reflecting device 2 is provided with a reflecting plate 24 that can move in the vertical direction, and the intensity of the reflected light is changed by moving the reflecting plate 24 in parallel in the vertical direction.

[0023] [Autonomous Robot 1] 2 is a perspective view showing the appearance of autonomous mobile robot 1. Autonomous mobile robot 1 includes a drive wheel attached to the bottom of the main body, a driven wheel rotatably attached to the bottom of the main body, a lidar sensor 14 that measures the distance to obstacles around autonomous mobile robot 1, a coupler 15, and a battery (not shown) that supplies power to the main body. Autonomous mobile robot 1 travels by estimating its own position based on the position of reflector 2 within a travel area identified based on changes in the intensity of reflected light. Autonomous mobile robot 1 is an example of a traveling device of the present disclosure.

[0024] The couplers 15 include a left coupler 15L and a right coupler 15R, which couple the carriage 3. While traveling along a set route, the autonomous mobile robot 1 can couple the carriage 3 with the couplers 15L and 15R at predetermined coupling positions (see FIG. 3) and travel while towing the carriage 3.

[0025] The lidar sensor 14 is a distance sensor (distance measurement device) capable of measuring the distance to an obstacle using a laser light L1. Specifically, the lidar sensor 14 uses mirrors and MEMS (Micro Electro Mechanical Systems) to project laser light L1 onto the surrounding area, receive the reflected light, and measure the time difference between the projection and reception to measure the distance to the obstacle in the direction of the laser projection. By repeating the projection direction of the laser light L1 in a fixed pattern, the location of obstacles in space can be observed at a frequency of several tens of hertz. The lidar sensor 14 is installed, for example, at the front center of the body of the autonomous mobile robot 1 (see FIGS. 2 and 3).

[0026] Here, a general method for estimating the self-position of the autonomous mobile robot 1 will be described.

[0027] Here, we take as an example a robot that moves in a parallel direction and turns by varying the speed of its left and right drive wheels. Such robots are often used as autonomous robots because they have a simple motion model and a large degree of freedom of movement. The robot moves in a straight line by rotating the left and right drive wheels in the same direction, and turns on the spot (stationary turning) by rotating them in opposite directions. In addition, by varying the speed of the left and right drive wheels, the robot can move in an arc. Note that the basic concept of self-localization is the same for robots that turn by varying the steering angle, like automobiles, except that the motion model changes.

[0028] The robot is equipped with left and right drive wheels and encoders (not shown) for measuring the rotation angle of each drive wheel.

[0029] First, the current posture (initial position) of the robot (autonomous mobile robot 1) is set on a map M1 (see Figure 4) corresponding to the travel area. This setting process may be performed by an operator on an operation terminal, or, if the robot starts travel from a charging station, it may be performed automatically by determining the position of the charging station on map M1 in advance.

[0030] The autonomous mobile robot 1 moves in a translational manner at the average speed of each drive wheel and turns according to the speed difference. The translational speed and turning speed can be calculated from the rotation angle per time measured by the encoder, the radius of the drive wheels, and the distance between the left and right drive wheels. In addition, the travel trajectory of the autonomous mobile robot 1 on the map M1 can be calculated by integrating the translational speed and turning speed.

[0031] Here, the speed obtained from the encoder observation value contains errors. These errors are due to errors in the radius of the drive wheels, errors in the spacing between the left and right drive wheels, slippage of the drive wheels, etc. As a result, the calculated trajectory of the autonomous mobile robot 1 on map M1 gradually deviates from the actual trajectory of the autonomous mobile robot 1.

[0032] As the autonomous mobile robot 1 continues to move, the positional deviation increases and eventually its own position becomes unknown, so the autonomous mobile robot 1 executes a correction process to correct its own position using the measurement results of the lidar sensor 14.

[0033] If the autonomous mobile robot 1's own position on the map M1 is correct, the arrangement of surrounding obstacles measured by the LIDAR sensor 14 will match the arrangement of obstacles on the map M1. If the measured arrangement of obstacles does not match the arrangement of obstacles on the map M1, the autonomous mobile robot 1 corrects its trajectory on the map M1 every time it moves a certain distance or turns a certain angle so that the arrangement of obstacles measured by the LIDAR sensor 14 matches the obstacles on the map M1. A specific method known is the Monte Carlo method.

[0034] In this way, the autonomous robot 1 travels along a predetermined route by measuring (detecting) surrounding obstacles using the lidar sensor 14 (see Figure 5) and estimating its own position by matching the obstacles with those on the map M1.

[0035] However, in a real environment, temporarily placed luggage, materials, and the cart 3 may be recognized as obstacles, or obstacles that should be recognized, such as pillars and walls, may be hidden by luggage and cannot be recognized, resulting in a mismatch between the positions of obstacles on the map M1 and the measured obstacles, making it difficult to accurately estimate the autonomous mobile robot's position. Therefore, the autonomous mobile system 10 according to this embodiment has a configuration that enables the use of a reflecting device 2 to improve the accuracy of estimating the autonomous mobile robot's position, as described below.

[0036] Specifically, as shown in FIG. 1, the autonomous mobile robot 1 includes a control unit 11, a memory unit 12, a communication unit 13, a lidar sensor 14, and the like.

[0037] The communication unit 13 is a communication interface for connecting the autonomous mobile robot 1 to a network wirelessly or by infrared light, and for executing data communication with an external device (such as a management server) via the network in accordance with a predetermined communication protocol.

[0038] The storage unit 12 is a non-volatile storage unit such as an HDD, SSD, or flash memory that stores various types of information. Specifically, the storage unit 12 stores route data received from the management server and the like.

[0039] The storage unit 12 also stores control programs such as an autonomous traveling program for causing the control unit 11 to execute an autonomous traveling process (see FIG. 9 ) described below. For example, the autonomous traveling program is non-temporarily recorded on a computer-readable recording medium such as a CD or DVD, and is read by a reading device (not shown) such as a CD drive or DVD drive provided in the autonomous traveling robot 1 and stored in the storage unit 12. The autonomous traveling program is an example of an autonomous traveling program of the present disclosure.

[0040] The control unit 11 has control devices such as a CPU, a ROM, and a RAM. The CPU is a processor that executes various types of arithmetic processing. The ROM is a non-volatile storage unit that pre-stores control programs such as a BIOS and an OS that cause the CPU to execute various types of arithmetic processing. The RAM is a volatile or non-volatile storage unit that stores various types of information and is used as a temporary storage memory (work area) for the various types of processing executed by the CPU. The control unit 11 controls the autonomous mobile robot 1 by having the CPU execute various control programs pre-stored in the ROM or the storage unit 12.

[0041] Specifically, the control unit 11 includes various processing units such as a driving processing unit 111. The control unit 11 functions as the various processing units by executing various processes in accordance with the autonomous driving program using the CPU. Some or all of the processing units may be configured with electronic circuits. The autonomous driving program may be a program that causes multiple processors to function as the processing units.

[0042] The driving processing unit 111 drives the autonomous mobile robot 1. Specifically, the driving processing unit 111 drives the autonomous mobile robot 1 along a preset driving route while estimating its own position on the map M1 using the well-known self-position estimation method described above. In this embodiment, it is assumed that the position of a pillar A1 (see FIG. 4) is registered on the map M1 stored in the storage unit 12. The driving processing unit 111 drives the autonomous mobile robot 1 along the driving route toward the destination while checking the position of the pillar A1.

[0043] For example, the driving processing unit 111 detects the position of the pillar by matching a point cloud of distance measurement points of the pillar A1 measured by the LIDAR sensor 14 with a pre-registered shape (template) of the pillar A1 (see FIG. 5). The driving processing unit 111 estimates its own position while matching the point cloud of distance measurement points of the pillar A1 measured by the LIDAR sensor 14 with the template, thereby causing the autonomous driving robot 1 to autonomously drive along a preset driving route.

[0044] Furthermore, the driving processing unit 111 estimates its own position by utilizing changes in the intensity of the light reflected by the reflecting device 2. Specifically, the reflecting device 2 changes the reflectance of the reflector 24 over time, and the driving processing unit 111 extracts a point cloud to be used for self-position estimation from the ranging point cloud, and estimates its own position based on the extracted point cloud. A specific example of self-position estimation will be described below.

[0045] 6A and 6B, the reflecting device 2 is disposed below the pillar A1, and the reflecting plate 24 is disposed so as to be movable parallel to the vertical direction relative to the base portion 23. For example, the reflecting plate 24 is configured so as to be able to alternately move at a predetermined period T between a first position that coincides with the scanning height of the laser light L1 emitted from the lidar sensor 14, i.e., an irradiation position where the laser light L1 is irradiated (see FIG. 6A), and a second position that is higher than the scanning height of the laser light L1, i.e., a non-irradiation position where the laser light L1 is not irradiated (see FIG. 6B).

[0046] The lidar sensor 14 receives reflected light that is emitted laser light L1 and reflected by the reflector 24. FIG. 7A shows the change over time in the intensity (reflection intensity) of the reflected light received by the lidar sensor 14. The reflector 2 alternately moves the reflector 24 between an irradiated position (see FIG. 6A) and a non-irradiated position (see FIG. 6B) at a predetermined period T, so that the reflection intensity changes between a first intensity r1 and a second intensity r2 at each period T. The first intensity r1 is a value smaller than the second intensity r2 and includes "0 (zero)."

[0047] Furthermore, when the reflector 24 is in the non-irradiation position, the laser light L1 is irradiated onto the base unit 23 (see FIG. 6B). By painting the base (surface) of the base unit 23 black, which has high absorbency of the laser light L1, the reflectivity is reduced, and the first intensity r1 can be further reduced, and the difference (change in brightness) between the first intensity r1 and the second intensity r2 can be made larger. This makes it easier to detect the pillar A1 on which the reflector 2 is placed, even if the distance between the reflector 24 and the autonomous mobile robot 1 is large.

[0048] Next, a specific example of a method for extracting a point cloud for self-position estimation from the range-finding point cloud of the LIDAR sensor 14 will be described.

[0049] FIG. 8A shows the ranging point cloud of the lidar sensor 14 relative to pillar A1. The lidar sensor 14 maps the ranging point cloud into two-dimensional space. The mapped point cloud is referred to as the "point cloud at time t" (see FIG. 8B). The ranging point cloud from a time T before is referred to as the "point cloud at time (tT)" (see FIG. 8B). The "point cloud at time (tT)" is configured using a FIFO (First In First Out) memory or the like.

[0050] As the autonomous mobile robot 1 moves over time T, the direction and distance of the reflector 24 as seen by the LIDAR sensor 14 change. Here, the movement amount of the LIDAR sensor 14 at time T can be calculated from the movement amount of each drive wheel at time T. Therefore, if the range measurement point cloud at time t is moved according to the movement amount of the LIDAR sensor 14 and superimposed on the range measurement point cloud at time (tT), the point clouds obtained by measuring the distance to the same obstacle will overlap at approximately the same position. As a result, for each range measurement point in the range measurement point cloud at time t, a range measurement point in the range measurement point cloud at time (tT) that spatially corresponds can be obtained.

[0051] For each ranging point in the point cloud at time t, the travel processing unit 111 extracts the nearest ranging point that is located less than a predetermined distance from the point cloud at time (tT). Furthermore, if the difference in the intensity of reflected light (reflection intensity) between the two extracted ranging points is equal to or greater than a predetermined value, the travel processing unit 111 determines that the ranging point is derived from the reflector 24 (reflected from the reflector 24). In the example shown in FIG. 8B, focusing on ranging point p1 in the point cloud at time t, the travel processing unit 111 extracts ranging point p2 from the point cloud at time (tT) that is located less than a predetermined distance from ranging point p1, calculates the difference between the reflection intensity of ranging point p1 (see FIG. 7A) and the reflection intensity of ranging point p2 extracted from the point cloud at time (tT) (see FIG. 7B), and determines that ranging point p1 is the ranging point corresponding to the position of the reflector 24 if the calculated intensity difference is equal to or greater than a predetermined value.

[0052] In contrast, if the difference in reflection intensity between the two extracted distance measurement points is less than a predetermined value, the traveling processing unit 111 determines that the distance measurement point is not a distance measurement point originating from the reflector 24, that is, a distance measurement point originating from another obstacle. In the example shown in Fig. 8B, if the difference (intensity difference) between the reflection intensity of distance measurement point p1 (see Fig. 7A) and the reflection intensity of distance measurement point p2 extracted from the point cloud at time (tT) (see Fig. 7B) is less than a predetermined value, the traveling processing unit 111 determines that distance measurement point p1 is a reflection from an obstacle other than the reflector 24.

[0053] The driving processing unit 111 extracts only the ranging points determined to be originating from the reflector 24 from the ranging point cloud. Note that the point cloud for time (tT) is output during periods when the reflection intensity is low, so the ranging point cloud is continuous. In this way, the driving processing unit 111 compares ranging points at the same location separated by time T, and determines that ranging points that have nearby ranging points and a large difference in brightness (difference in reflection intensity) are originating from the reflector 24.

[0054] The travel processing unit 111 detects the position of the pillar A1 on which the reflector 24 is located by matching a point cloud of the range-finding points determined to be caused by the reflector 24 with a pre-registered shape (template) of the pillar A1. The travel processing unit 111 then estimates its own position while matching the point cloud of the range-finding points determined to be caused by the reflector 24 with the template, thereby causing the autonomous mobile robot 1 to travel autonomously along a pre-set travel route. In this way, the travel processing unit 111 estimates its own position using, among the range-finding points of an obstacle identified based on the reflected light received by the LIDAR sensor 14, those where the amount of change in light intensity over time is equal to or greater than a predetermined value.

[0055] As described above, by changing the reflection intensity of the laser light L1 at a preset cycle T (frequency), it is possible to accurately separate the ranging points resulting from the reflector 24 from those resulting from other obstacles. This makes it possible to use only the ranging points corresponding to the placement position of the reflector 24 on the map M1 in the self-location estimation process. For example, it is possible to reduce the influence on self-location estimation of ranging points resulting from obstacles that have high reflection intensity but are not reflectors, such as pieces of metal.

[0056] Furthermore, for ranging points with low reflection intensity far from the autonomous mobile robot 1, by detecting changes in reflection intensity, it is possible to determine whether the ranging point originates from the reflector 24, which has the effect of extending the ranging range. Furthermore, since ranging points farther away can be used, the number of ranging points used for self-location estimation can be increased, and the accuracy of self-location estimation can be improved.

[0057] [Autonomous driving processing] An example of the autonomous driving process executed by the autonomous driving system 10 will be described below with reference to FIG.

[0058] The present disclosure can be understood as a disclosure of an autonomous driving method that executes one or more steps included in the autonomous driving process. The autonomous driving method is an example of the autonomous driving method of the present disclosure. One or more steps included in the autonomous driving process described here may be omitted as appropriate. The steps in the autonomous driving process may be executed in a different order as long as the same effects are achieved. In this embodiment, the control unit 11 of the autonomous driving robot 1 executes each step in the autonomous driving process. The method may also be an autonomous driving method in which one or more processors execute each step in the autonomous driving process in a distributed manner.

[0059] <Step S1> In step S1, when the control unit 11 of the autonomous mobile robot 1 receives a travel instruction from the management server, it starts autonomous travel along a preset travel route. Specifically, the control unit 11 measures the distance to an obstacle based on the time difference between when the laser light L1 is emitted and when it is received by the lidar sensor 14, and estimates its own position while matching the range-finding point cloud of the pillar A1 with the template, thereby causing the autonomous mobile robot 1 to travel autonomously along the travel route.

[0060] <Step S2> In step S2, the control unit 11 acquires the coordinates of the distance measurement points in the two-dimensional space at time t. For example, as shown in Fig. 8B, the control unit 11 acquires a point cloud at time t.

[0061] <Step S3> In step S3, the control unit 11 searches for the coordinates of the nearest ranging point at time (tT). For example, in the example shown in FIG. 8B, the control unit 11 extracts ranging point p2, which is nearest to ranging point p1, from the point cloud at time (tT). Note that time T is a preset cycle for changing the intensity of reflected light from the reflector 24. For example, if the cycle is 2T, the control unit 11 searches for the coordinates of the nearest ranging point at time (t-2T).

[0062] <Step S4> In step S4, the control unit 11 determines whether the distance between the ranging point at time t and the ranging point at time (tT) is less than a predetermined distance. Specifically, the control unit 11 determines whether the distance to the nearest ranging point extracted from the point cloud at time (tT) is less than a predetermined distance. For example, the control unit 11 determines whether the distance between ranging point p1 in the point cloud at time t and ranging point p2 at time (tT) is less than a predetermined distance. If the distance between the two ranging points is less than the predetermined distance (S4: Yes), the control unit 11 shifts the processing to step S5. On the other hand, if the distance between the two ranging points is equal to or greater than the predetermined distance (S4: No), the control unit 11 shifts the processing to step S41.

[0063] <Step S5> In step S5, the control unit 11 determines whether the difference between the reflection intensity of the ranging point at time t and the reflection intensity of the ranging point at time (tT) is equal to or greater than a predetermined value. For example, the control unit 11 calculates the difference between the reflection intensity of ranging point p1 at time t (see FIG. 7A) and the reflection intensity of ranging point p2 at time (tT) (see FIG. 7B), and determines whether the calculated intensity difference is equal to or greater than a predetermined value. If the intensity difference is equal to or greater than the predetermined value (S5: Yes), the control unit 11 shifts the process to step S6. On the other hand, if the intensity difference is less than the predetermined value (S5: No), the control unit 11 shifts the process to step S41.

[0064] <Step S6> In step S6, the control unit 11 determines that the target distance measurement point is a distance measurement point derived from the reflector 24 (reflected from the reflector 24). Specifically, if the distance to the distance measurement point at time (tT) is less than a predetermined distance (S4: Yes) and the difference in reflection intensity (intensity difference) from the distance measurement point at time (tT) is equal to or greater than a predetermined value (S5: Yes), the control unit 11 determines that the distance measurement point is a distance measurement point derived from the reflector 24. After step S6, the control unit 11 causes the process to proceed to step S7.

[0065] <Step S41> In step S41, the control unit 11 determines that the target distance measurement point is a distance measurement point of an obstacle other than the reflector 24 (reflected from an obstacle other than the reflector 24). Specifically, if the distance to the distance measurement point at time (tT) is equal to or greater than a predetermined distance (S4: No), or if the difference in reflection intensity (intensity difference) from the distance measurement point at time (tT) is less than a predetermined value (S5: No), the control unit 11 determines that the distance measurement point is a distance measurement point of an obstacle other than the reflector 24. After step S41, the control unit 11 causes the process to proceed to step S7.

[0066] <Step S7> In step S7, the control unit 11 determines whether the determination process has been completed for all the distance measurement points of the point cloud at time t. If the control unit 11 has completed the determination process for all the distance measurement points of the point cloud at time t (S7: Yes), the control unit 11 proceeds to step S8. On the other hand, if the control unit 11 has not completed the determination process for all the distance measurement points of the point cloud at time t (S7: No), the control unit 11 returns the process to step S2 and executes the above-mentioned process. The control unit 11 repeatedly executes the above-mentioned process until the determination process has been completed for all the distance measurement points of the point cloud at time t.

[0067] <Step S8> In step S8, the control unit 11 estimates the self-position of the autonomous mobile robot 1. Specifically, the control unit 11 detects the position of the pillar A1 by matching a point cloud of ranging points determined to be derived from the reflector 24 among the ranging points with a pre-registered shape (template) of the pillar A1. The control unit 11 then estimates the self-position while matching the point cloud of ranging points determined to be derived from the reflector 24 with the template, thereby causing the autonomous mobile robot 1 to autonomously travel along a pre-set travel route. The control unit 11 also estimates the self-position by excluding ranging points (S41) of obstacles other than the reflector 24 from the ranging points.

[0068] The control unit 11 repeatedly executes the above-described process until the autonomous mobile robot 1 arrives at the destination.

[0069] As described above, the autonomous mobile system 10 according to this embodiment includes the reflecting device 2 that is placed at a predetermined position in the travel area and reflects the emitted laser light L1, and the autonomous mobile robot 1 that is equipped with a sensor (lidar sensor 14) that emits the laser light L1 and receives the light reflected from the reflecting device 2, and that estimates its own position based on the reflected light. Furthermore, when the reflecting device 2 receives the laser light L1 emitted from the lidar sensor 14, it changes the intensity of the reflected light, and the autonomous mobile robot 1 estimates its own position based on the position of the reflecting device 2 within the travel area that is identified based on the change in the intensity of the reflected light, and travels.

[0070] According to the above configuration, the reflector 2 can be reliably recognized by utilizing the change in the intensity of reflected light over time, and the position of the reflector 2 on the map M1 corresponding to the driving area can be accurately grasped. Therefore, even in a situation where it is difficult to recognize obstacles (walls, pillars, etc.) that can be used to correct the self-position, the self-position can be estimated by utilizing the position of the reflector 2. This improves the accuracy of estimating the self-position.

[0071] [Other embodiments] In another embodiment of the autonomous driving system 10 according to the present disclosure, the reflecting device 2 may have a configuration ("second configuration") in which the reflecting plate 24 is rotatable in the vertical direction and the intensity of the reflected light is changed by rotating the reflecting plate 24 in the vertical direction. For example, the reflecting device 2 alternately rotates the reflecting plate 24 between a first position (see FIG. 10A) facing the scanning direction of the laser light L1 and a second position (see FIG. 10B) facing a direction different from the scanning direction of the laser light L1 at a predetermined period T. The retroreflecting plate 24 has the property of reflecting light in the direction of incidence of the laser light L1, but its reflectivity decreases when the laser light L1 is incident at an angle compared to when the laser light L1 is incident from the front. Therefore, the reflection intensity can be varied by rotating the reflecting plate 24 to change the angle of incidence. As a result, as shown in FIGS. 11A and 11B, the change in the reflection intensity of the reflected light received by the LIDAR sensor 14 forms a waveform close to a sine wave.

[0072] As in the above-described embodiment (first configuration), the travel processing unit 111 extracts a ranging point where the difference between the reflection intensity of the ranging point at time t and the reflection intensity of the nearest ranging point at time T earlier (tT) is large, and estimates the self-position. In this embodiment (second configuration), the operation of the reflector 24 is rotation, which is compatible with the motor that is the driving component. In other words, the second configuration has fewer moving parts than the above-described first configuration, making it more resistant to breakdowns and also advantageous in terms of cost.

[0073] In the first configuration described above, the reflection intensity has a waveform close to a square wave (see FIGS. 8A and 8B), but in the second configuration of this embodiment, the waveform is close to a sine wave, so there is a period when the intensity difference is small, and during that period, it is not possible to acquire distance measurement points derived from the reflector 24. However, it is possible to fill in the blank period by leaving the distance measurement point group in space for a survival period of T.

[0074] In another embodiment, the reflection device 2 may be configured ("third configuration") to include a shutter unit on the front surface of the reflector 24 that changes the transmittance of the laser light L1 irradiated onto the reflector 24, and to change the intensity of the reflected light by driving the shutter unit. For example, the shutter unit may be configured as a liquid crystal shutter or a shielding plate. For example, the control unit 11 changes the transmittance by changing the voltage applied to the liquid crystal shutter to control the orientation of the liquid crystal. By changing the transmittance, the reflection intensity of the reflected light received by the LIDAR sensor 14 can be changed. Furthermore, the control unit 11 changes the reflector 24 between an exposed state and a covered state by translating the shielding plate, which is arranged to cover the reflector 24, in the vertical or horizontal direction.

[0075] The liquid crystal shutter configuration has no mechanically driven parts, so it is less prone to malfunction and has excellent durability. It can also be made to blink at a higher speed.

[0076] During periods when the reflectivity is low, the object becomes difficult to see, and the autonomous mobile robot 1 continues to move during those periods. As mentioned above, it is possible to eliminate blank periods during periods when the object becomes difficult to see by interpolating using a point cloud observed in the past, but this may result in a large discrepancy with the actual object when moving at high speeds. In such cases, it is better to make the reflector blink as fast as possible to shorten the period when the object becomes difficult to see, thereby reducing the discrepancy in the detected position of the reflector 24 and maintaining the accuracy of the autonomous mobile robot's position. Therefore, when increasing the traveling speed of the autonomous mobile robot 1, a configuration that does not use mechanical components such as the liquid crystal shutter is preferable.

[0077] As another embodiment, in each of the above-described configurations, the period T of the posture change of the reflecting device 2 may be different for each placement position of the reflecting device 2. For example, as shown in FIG. 12, the period T for alternately moving the reflector 24 between an irradiation position (first position) where the laser light L1 is irradiated and a non-irradiation position (second position) where the laser light L1 is not irradiated may be set for each pillar A1. The autonomous mobile robot 1 stores in advance the blinking period for each pillar A1 on the map M1. As a result, the blinking period varies for each pillar A1, and the control unit 11 can determine between which pillars A1 the autonomous mobile robot 1 is likely to be currently located by comparing the observed blinking period with the blinking period set in advance for each pillar A1 on the map M1.

[0078] For example, consider a case where there are only two types of cycles (first cycle and second cycle) and the cycles observed by the autonomous mobile robot 1 are as shown in Figure 13. The white and black squares represent pillars A1 equipped with reflectors 24 with different blinking cycles. In this case, the probability of the autonomous mobile robot 1 being between the pillars A1 is narrowed down to 1 / 2. As mentioned above, the self-position is based on the cumulative self-position acquired from the wheels, so the self-position does not jump significantly. Therefore, narrowing down the probability to about 1 / 2 is practically acceptable, and is well worthwhile in terms of improving reliability by corroborating the self-position. Furthermore, increasing the number of cycle types allows the possibility to be narrowed down even more, further improving reliability.

[0079] [Application example] Next, a configuration example will be shown that uses the blinking of the reflector 24 to perform functions other than self-position estimation. In this configuration example, the control unit 11 executes control to stop the autonomous mobile robot 1 when it cannot detect the blinking of the reflector 24. This makes it possible to stop all the autonomous mobile robots 1 quickly and simultaneously by stopping the drive of the reflector 24 in an emergency.

[0080] Normally, commands are sent to a moving autonomous mobile robot 1 via wireless communication. However, it is difficult to guarantee stable communication everywhere with wireless, and if a wireless communication interruption causes the robot to stop moving, it may stop frequently. Therefore, when commands are sent via wireless communication, it is common to configure the program so that the robot can continue to move autonomously to a certain extent even if the wireless communication is interrupted.

[0081] However, on the other hand, if it is necessary to stop all autonomous mobile robots 1 in an emergency, there is a possibility that autonomous mobile robots 1 that did not receive the emergency stop command via wireless may continue to operate. In this regard, the reflector 24 is installed on the pillar A1, and commands can be sent via wire. Therefore, commands can be executed more stably than via wireless.

[0082] Since the autonomous mobile robot 1 always captures several pillars A1 to estimate its own position, it can transmit commands stably by stopping the reflector 24 and transmitting the command. Complex commands such as those transmitted via wireless communication cannot be transmitted simply by determining whether or not to drive, but for simple and important commands such as an emergency stop, wireless communication failures can be compensated for and reliability can be improved.

[0083] [Features of the present disclosure] The autonomous mobile robot 1 in the present disclosure uses a distance measurement sensor such as a LIDAR sensor 14 to estimate its own position on a map M1 prepared in advance. Specifically, the autonomous mobile robot 1 installs reflectors 24 on obstacles used for self-position estimation, such as pillars and walls, and estimates its own position using only distance measurement points where the amount of time change in the reflection intensity of laser light L1 acquired by the distance measurement sensor is equal to or greater than a predetermined value. The reflection intensity of the reflector 24 is also changed over time.

[0084] Furthermore, the reflection intensity is changed over time by moving the reflector 24 to change the position and angle at which the laser light L1 of the distance measuring sensor is irradiated.

[0085] In addition, a cover (shielding plate) is provided in front of the reflector 24, and the reflection intensity is changed over time by moving the shielding plate.

[0086] Furthermore, by placing a device capable of varying transmittance, such as a liquid crystal shutter, in front of the reflector 24, the reflection intensity is changed over time.

[0087] Furthermore, the autonomous mobile robot 1 extracts distance measurement points where the reflection intensity changes over time, and estimates its own position using the distance measurement points.

[0088] Furthermore, the frequency of the time change is set to be different for each reflector 24 .

[0089] Furthermore, the location of the autonomous mobile robot 1 is narrowed down by comparing the arrangement of the frequency of the time change of the reflector 24 on the map M1 with the arrangement of the measured time change of the reflector 24.

[0090] In addition, by stopping the time-dependent changes of the reflectors 24 all at once, commands such as an emergency stop can be transmitted.

[0091] [effect] For example, by changing the reflection intensity at a preset frequency, it is possible to accurately separate the ranging points resulting from the reflector 24 from those resulting from other obstacles. This makes it possible to use only the ranging points corresponding to the placement of the reflector 24 on the map M1 for self-location estimation. It is also possible to reduce the impact on self-location estimation of obstacles that are not reflectors 24 but have high reflection intensity, such as metal pieces.

[0092] Furthermore, by detecting the change in reflection intensity for a distant ranging point where the reflection intensity has decreased, it is possible to determine that the ranging point originates from the reflector 24, which has the effect of extending the ranging range. By using ranging points that are farther away, it is possible to increase the number of ranging points used for self-position estimation, thereby improving accuracy.

[0093] Furthermore, in a configuration in which each reflector 24 is driven so that the frequency of time change differs, the arrangement of frequencies on map M1 is made known, and by comparing the arrangement of frequencies of time change of reflector 24 with the arrangement of frequencies on map M1, it becomes possible to roughly narrow down the self-position, thereby improving the accuracy of the self-position.

[0094] Furthermore, by simultaneously stopping the drive of multiple reflectors 24, it becomes possible to transmit commands via other than the normal transmission route, such as wireless communication, thereby improving the reliability of transmission of important commands such as emergency stops.

[0095] The control unit 11 of the autonomous mobile robot 1 controls the entire autonomous mobile robot 1. The control unit 11 realizes various functions by reading and executing various programs stored in the memory unit 12 (for example, storage or ROM). The control unit 11 may be realized by one or more control devices / arithmetic units (CPUs (Central Processing Units), SoCs (System on a Chip)). The control unit 11 may also be configured by one or more control circuits (electronic circuits).

[0096] [Disclosure Note] The following will provide an outline of the disclosure extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0097] <Appendix 1> a reflecting device that is arranged at a predetermined position in the travel area and reflects the light emitted by the laser; a traveling device that includes a sensor that emits the laser light and receives reflected light of the laser light reflected by the reflecting device, and that travels by estimating its own position based on the reflected light; An autonomous driving system comprising: the reflecting device changes the intensity of the reflected light when receiving the laser light emitted from the sensor, the traveling device estimates its own position based on the position of the reflecting device within the traveling area identified based on the change in intensity of the reflected light, and travels. Autonomous driving system.

[0098] <Appendix 2> The reflecting device includes a reflecting plate whose position can be changed, and the intensity of the reflected light is changed by changing the position of the reflecting plate. 10. A traction system as described in appendix 1.

[0099] <Appendix 3> the reflecting device includes a reflecting plate that is movable in the vertical direction, and the intensity of the reflected light is changed by translating the reflecting plate in the vertical direction. 3. A driving system according to claim 1 or 2.

[0100] <Appendix 4> the reflecting device alternately moves the reflecting plate between a first position that coincides with the scanning height of the laser light and a second position that is different from the scanning height of the laser light at a predetermined cycle; 1. A running system as described in appendix 3.

[0101] <Appendix 5> the reflecting device includes a reflecting plate that can rotate in an up-down direction, and the intensity of the reflected light is changed by rotating the reflecting plate in an up-down direction. 3. A driving system according to claim 1 or 2.

[0102] <Appendix 6> the reflecting device alternately rotates the reflecting plate between a first position facing the scanning direction of the laser light and a second position facing a direction different from the scanning direction of the laser light at a predetermined cycle; 10. A running system as described in appendix 5.

[0103] <Appendix 7> the reflecting device includes a shutter unit on a front surface of a reflecting plate that changes the transmittance of the laser light irradiated onto the reflecting plate, and the intensity of the reflected light is changed by driving the shutter unit. 3. A driving system according to claim 1 or 2.

[0104] <Appendix 8> the traveling device estimates its own position using a distance measurement point of an obstacle identified based on the reflected light received by the sensor, where the time change in light intensity is equal to or greater than a predetermined value; A traveling system according to any one of appendices 1 to 7.

[0105] <Appendix 9> An autonomous driving method for autonomously driving a traveling device that emits laser light and has a sensor that receives reflected light of the laser light reflected by a reflector disposed at a predetermined position in a traveling area, by estimating its own position based on the reflected light, comprising: the reflecting device changes the intensity of the reflected light when receiving the laser light emitted from the sensor; the traveling device estimates its own position based on the position of the reflecting device within the traveling area identified based on the change in the intensity of the reflected light and travels. Autonomous driving method.

[0106] <Appendix 10> An autonomous driving program that causes a traveling device to autonomously travel by estimating its own position based on the reflected light, the autonomous driving program comprising: a traveling device that emits laser light and has a sensor that receives reflected light of the laser light reflected by a reflecting device disposed at a predetermined position in a traveling area; When the reflecting device receives the laser light emitted from the sensor, the intensity of the reflected light is changed; causing the traveling device to travel while estimating its own position based on a position of the reflecting device within the traveling area identified based on a change in the intensity of the reflected light; An autonomous driving program, or a non-transitory computer-readable recording medium on which the autonomous driving program is recorded. [Explanation of symbols]

[0107] 1: Autonomous driving robot 2:Reflector 3: Cart 10: Autonomous driving system 11: Control section 12: Storage section 13: Communications Department 14: Lidar sensor 15:Coupler 21: Control unit 22: Storage section 23: Base part 24:Reflector 111: Driving processing unit A1: Pillar L1: Laser light M1: Map T :period

Claims

1. a reflecting device that is arranged at a predetermined position in the travel area and reflects the irradiated laser light; a traveling device that includes a sensor that emits the laser light and receives reflected light of the laser light reflected by the reflecting device, and that travels by estimating its own position based on the reflected light; An autonomous driving system comprising: the reflecting device changes the intensity of the reflected light when receiving the laser light emitted from the sensor, the traveling device estimates its own position based on the position of the reflecting device within the traveling area identified based on the change in intensity of the reflected light, and travels. Autonomous driving system.

2. The reflecting device includes a reflecting plate whose position can be changed, and the intensity of the reflected light is changed by changing the position of the reflecting plate. The autonomous driving system according to claim 1 .

3. the reflecting device includes a reflecting plate that is movable in the vertical direction, and the intensity of the reflected light is changed by translating the reflecting plate in the vertical direction. The autonomous driving system according to claim 1 .

4. the reflecting device alternately moves the reflecting plate between a first position that coincides with the scanning height of the laser light and a second position that is different from the scanning height of the laser light at a predetermined cycle; The autonomous driving system according to claim 3 .

5. the reflecting device includes a reflecting plate that can rotate in an up-down direction, and the intensity of the reflected light is changed by rotating the reflecting plate in an up-down direction. The autonomous driving system according to claim 1 .

6. the reflecting device alternately rotates the reflecting plate between a first position facing the scanning direction of the laser light and a second position facing a direction different from the scanning direction of the laser light at a predetermined cycle; The autonomous driving system according to claim 5 .

7. the reflecting device includes a shutter unit on a front surface of a reflecting plate that changes the transmittance of the laser light irradiated onto the reflecting plate, and the intensity of the reflected light is changed by driving the shutter unit. The autonomous driving system according to claim 1 .

8. the traveling device estimates its own position using a distance measurement point of an obstacle identified based on the reflected light received by the sensor, where the time change in light intensity is equal to or greater than a predetermined value; The autonomous driving system according to any one of claims 1 to 7.

9. An autonomous driving method for autonomously driving a traveling device that emits laser light and has a sensor that receives reflected light of the laser light reflected by a reflector disposed at a predetermined position in a traveling area, by estimating its own position based on the reflected light, comprising: the reflecting device changes the intensity of the reflected light when receiving the laser light emitted from the sensor; the traveling device estimates its own position based on the position of the reflecting device within the traveling area identified based on the change in the intensity of the reflected light and travels. Autonomous driving method.

10. An autonomous driving program that causes a traveling device to autonomously travel by estimating its own position based on the reflected light, the autonomous driving program comprising: a traveling device that emits laser light and has a sensor that receives reflected light of the laser light reflected by a reflecting device disposed at a predetermined position in a traveling area; When the reflecting device receives the laser light emitted from the sensor, the intensity of the reflected light is changed; causing the traveling device to travel while estimating its own position based on a position of the reflecting device within the traveling area identified based on a change in the intensity of the reflected light; Autonomous driving program.

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