JP7725972B2 - Transport system and control method thereof - Google Patents

Description

The present invention relates to a transport system using a self-propelled transport device.

In recent years, there has been an increasing number of cases in manufacturing and logistics sites where self-propelled transport devices are being introduced to transport carts loaded with goods. By replacing all or part of the cart transport work previously performed by humans with self-propelled transport devices, productivity and safety can be improved, and labor savings can be achieved.

The main types of self-propelled transport devices are AGVs (Automatic Guided Vehicles) and AMRs (Autonomous Mobile Robots). AGVs, also known as automated guided vehicles or robots, are transport devices that travel along predetermined routes by following guides such as magnetic tape laid on the floor or beacons attached to the wall. Meanwhile, AMRs, also known as autonomous transport robots or mobile robots, are transport devices that use sensors to constantly recognize their own position and the presence or absence of obstacles, and autonomously select an appropriate travel route.

Patent Document 1 discloses an AGV that tows a cart.

JP 2014-186680 A

The cart transport task using the self-propelled transport device is generally performed as follows.
(1) First, a worker places a cart to be transported at point A.
(2) The host system notifies the self-propelled transport device of the cart's pick-up position (point A) and drop-off position (point B).
(3) The self-propelled transport device goes to point A, picks up a cart present there, and then moves to point B and drops off the cart.

Such conventional methods can encounter the following problems. For example, if the worker places the cart to be transported at point A with an incorrect position or posture, or if the worker forgets to place the cart at point A in the first place, the self-propelled transport device will fail to pick up the cart, and the transport task will be interrupted. Furthermore, if the worker mistakenly places a different cart at point A, a cart other than the one to be transported will be picked up and transported to point B. Even if the cart is successfully picked up, if another cart is already placed at point B or if there is some kind of obstacle, the self-propelled transport device may not be able to drop off the cart and the task may not be completed. The problems described here are particularly concerning in situations where humans and self-propelled transport devices work together, i.e., in situations where both the worker and the self-propelled transport device may be moving the cart.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide technology for improving the reliability and convenience of cart transport using a self-propelled transport device.

The present disclosure includes a transport system characterized by having a cart position detection means for detecting the position of each of multiple carts that may be transported; a transport instruction generation means for generating transport instructions including information on a pickup position for picking up the transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detection means; and a self-propelled transport device for transporting a cart present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generation means.

The transport instruction generation means may receive a transport task to transport a first cart to a first position, and generate a transport instruction that sets the position of the first cart detected by the cart position detection means as a pick-up position and the first position as a drop-off position.

The transport instruction generation means may receive a transport task to transport a cart located at a second position to a position adjacent to a second cart, calculate a third position where the cart to be transported can be dropped off based on the position of the second cart detected by the cart position detection means, and generate a transport instruction that sets the second position as a pickup position and the third position as a drop-off position.

The transport instruction generation means may receive a transport task to transport a third cart to a position adjacent to a fourth cart, calculate a fourth position where the cart to be transported can be dropped off based on the position of the fourth cart detected by the cart position detection means, and generate a transport instruction that sets the position of the third cart detected by the cart position detection means as a pickup position and the fourth position as a drop-off position.

The cart position detection means may be configured to include a positioning device mounted on each cart and a position information receiving means for receiving from each cart the position information measured by the positioning device.

The positioning device may have a driving condition detection means for detecting the driving condition of the cart, and may change the frequency of positioning depending on the driving condition detected by the driving condition detection means.

The positioning device may have a generator that generates electricity through the rotation of the cart's wheels and operate using the power from the generator.

The cart position detection means may be configured to include an identification information transmission device mounted on each cart, multiple receiving devices that receive signals transmitted from the identification information transmission device, and positioning means that calculates the position of each cart based on the strength of the signals received by the multiple receiving devices.

The identification information transmission device may have a driving state detection means for detecting the driving state of the cart, and may change the frequency of transmission depending on the driving state detected by the driving state detection means.

The identification information transmission device may have a generator that generates electricity through the rotation of the cart's wheels and operate using the power from the generator.

The transport instruction generation means may further include, in the transport instruction, information indicating the orientation of the transport target cart when the transport target cart is picked up.

The transport instruction generation means may further include, in the transport instruction, information indicating the orientation of the cart to be transported when the cart to be transported is dropped off.

The self-propelled transport device may further include a pickup operation change means that changes the pickup position of the cart to be transported or stops transport if the position of the cart to be transported changes before the self-propelled transport device picks up the cart to be transported.

The self-propelled transport device may further include a drop-off operation change means that changes the location at which the target cart is dropped off or stops transport if another cart is placed at the drop-off position before the self-propelled transport device transports the target cart to the drop-off position.

The present disclosure includes a method for controlling a conveyance system, comprising: a cart position detection step for detecting the position of each of a plurality of carts that may be the target of conveyance; a conveyance instruction generation step for generating, based on the position of each cart detected in the cart position detection step, conveyance instructions including information on a pickup position for picking up the cart to be conveyed and information on a drop-off position for dropping off the cart to be conveyed; and a step for causing a self-propelled conveyance device to perform a conveyance operation for conveying the cart present at the pickup position to the drop-off position in accordance with the conveyance instructions generated in the conveyance instruction generation step.

The present invention may be understood as a transport system having at least some of the above means, or as the management device, self-propelled transport device, or cart, which are components of the transport system. The present invention may also be understood as a control method for a transport system that includes at least some of the above processes, or a program for implementing such a method, or a recording medium on which such a program is recorded. The above means and processes may be combined with each other to the greatest extent possible to constitute the present invention.

This invention makes it possible to improve the reliability and convenience of cart transport using a self-propelled transport device.

FIG. 1 is a diagram showing a transport system as an example of application of the present invention. FIG. 2 is a diagram illustrating an example of the configuration of the transport system according to the first embodiment. FIG. 3 is a diagram illustrating an example of the flow of the cart transport process according to the first embodiment. FIG. 4 is a plan view showing the cart transport operation by the mobile robot. FIG. 5 is a diagram showing an example of a configuration using GPS positioning. FIG. 6 is a plan view showing an example of a configuration using Wi-Fi positioning. FIG. 7 is a plan view showing an example of a configuration using a beacon. 8A and 8B are diagrams showing examples of operational rules for placing carts. 9A and 9B are diagrams showing an example of the configuration of a function for detecting the orientation of a cart. FIG. 10 is a diagram illustrating an example of the configuration of a transport system according to the third embodiment. FIG. 11 is a diagram illustrating an example of the operation of the positioning device according to the third embodiment. FIG. 12 is a diagram showing an example of the flow of the pickup operation change process and the drop-off operation change process according to the fourth embodiment. FIG. 13 is a diagram illustrating an example of the configuration of a positioning device according to the fifth embodiment. FIG. 14 is a diagram illustrating an example of the configuration of a transport system according to the sixth embodiment. FIG. 15 is a diagram showing an example of the flow of the cart transport process according to the sixth embodiment. FIG. 16 is a diagram showing a modified example of the transport system of the sixth embodiment. 17A and 17B are diagrams showing examples of rules for changing drop-off positions in the seventh embodiment.

<Application example>
Referring to FIG. 1, a transport system as an application example of the present invention will be described.

A transport system is a system for automatically transporting carts at manufacturing, logistics, and other sites, and is composed, for example, of one or more self-propelled transport devices and a management device that manages their operation. A self-propelled transport device is a device that transports a cart from one point to another in accordance with transport instructions from the management device. Here, we assume that the self-propelled transport device is an AMR that runs on motor power, but an AGV or a transport device other than a vehicle may also be used. A cart is a platform for carrying goods or people. Here, we assume that the cart does not have a power source such as an engine or motor, and is moved by a self-propelled transport device or a worker.

A distinctive feature of this transport system is its "cart position detection" function, which detects the location of each of multiple carts that may be transported. Manufacturing and logistics sites may use dozens or even hundreds of carts, and it is desirable for the transport system to be able to detect and understand in real time where these carts are located within the transport area. This function makes it possible to use a new "transport task by specifying an individual cart" in addition to the conventional "transport task by specifying a position." The term "transport task" refers to the task of transporting a single cart from one point to another.

A "transportation task with specified location" is a task defined by explicitly specifying the cart pickup and drop-off locations. For example, in a conventional transport system, a user or management device might issue instructions to a self-propelled transport device such as, "Go to coordinates (x1, y1), pick up the cart, move to coordinates (x2, y2), and drop off the cart." Of course, in many cases, this type of transport task poses no problems. However, the operation of this transport task is possible only because it assumes that the cart to be transported is properly set up at position (x1, y1) by a worker or other device before the self-propelled transport device arrives at the pickup location (x1, y1), and that there is space to place the cart at the drop-off location (x2, y2). If this assumption were violated—for example, if there was an error in setting up the cart at the pickup location or if another cart was already placed at the drop-off location—the transport task could fail, potentially resulting in an error or accident.

One effective solution to this problem is a "transport task by specifying an individual cart." A "transport task by specifying an individual cart" is a task that is defined by specifying the individual cart or a relative position based on the individual cart, rather than specifying the pickup or drop-off position using coordinates. This system's cart position detection function makes it possible to detect and understand the position of each individual cart, making it possible to specify individual carts in this way.

As an example, the following variations of the specification method are possible.
(1) A method of specifying the cart to be transported and specifying the drop-off position using coordinates. Example: Transport the first cart (cart ID: c1) to the first position (x, y). (2) A method of specifying the pickup position using coordinates and specifying the drop-off position relative to other carts. Example: Transport the cart (cart ID may be specified or unknown) located at the second position (x, y) to next to the second cart (cart ID: c2). (3) A method of specifying the cart to be transported and specifying the drop-off position relative to other carts. Example: Transport the third cart (cart ID: c3) to next to the fourth cart (cart ID: c4).

When a cart to be transported is designated using designation methods (1) and (3), the management device or self-propelled transport device acquires the current position of the cart to be transported and recognizes the pickup position of the cart to be transported. When a drop-off position is designated using designation methods (2) and (3), the management device or self-propelled transport device acquires the current positions of the "other carts" and calculates a position where the cart to be transported can be dropped off based on the positions of the "other carts."

In this way, by directly specifying the cart to be transported, as in methods (1) and (3), the self-propelled transport device can pick up the cart to be transported no matter where it is located. This allows for greater leeway in the setup position of the cart to be transported, making operation easier. It also prevents mistakes such as transporting the wrong cart by mistake.

Furthermore, by using methods (2) and (3) to specify the drop-off position based on other carts, it is easy to line up multiple carts in an orderly manner at the drop-off position. It is also possible to control the placement of the cart to be transported in a position that avoids carts that are already placed, which is extremely convenient.

"Transportation tasks based on individual cart designation" is particularly advantageous in workplaces where humans and self-propelled transport devices work together. For example, because a self-propelled transport device can pick up a cart without setting it up in a predetermined location, a cart in any location or placed arbitrarily can be handed over to the self-propelled transport device. Even if a worker shifts the position of a cart during work, the pickup and drop-off positions can be automatically corrected to match the cart's current location, preventing transport failures. Furthermore, automatic transport by a self-propelled transport device and manual transport by a worker can coexist. In conventional systems, if a worker transports a cart on their own, the self-propelled transport device will lose track of the cart to be picked up, causing an error. In contrast, this system monitors the location of the cart to be transported for each transport task, and can detect when a transport task has been completed by a worker manually transporting it and cancel the transport task. This enables dynamic work sharing between humans and self-propelled transport devices.

Furthermore, by utilizing the ability to track the location of each cart on the transport system side, it is possible to visualize the transport cycle from the cart's perspective, leading to improvements in the transport process. For example, the time between issuing a transport command to a self-propelled guided vehicle and the actual start of the cart's transport can be visualized as "transport wait time." This transport wait time can be used as a key performance indicator (KPI) for improvement activities. For example, the number of self-propelled guided vehicles and the number of workers can be adjusted to minimize transport wait time. Alternatively, the time required for the same transport operation to be performed by a human and by a self-propelled guided vehicle can be compared. Based on the results, the self-propelled guided vehicle map can be improved or which items should be transported by a human (i.e., not automated), thereby optimizing the allocation of people and self-propelled guided vehicles.

First Embodiment
A first embodiment of the present invention will be described with reference to Fig. 2. Fig. 2 is a diagram schematically showing an example of the configuration of a transport system according to the first embodiment.

The transport system 1 generally comprises a management device 10, a mobile robot 11 as a self-propelled transport device, and a cart 12. For illustrative purposes, Figure 2 shows only one mobile robot 11 and one cart 12; however, in practice, multiple mobile robots 11 and multiple carts 12 are typically used depending on the size of the site where the transport system 1 is operated and the volume of goods to be transported.

The management device 10 is a device for managing the operation of multiple mobile robots 11. In this embodiment, the management device 10 has the following main functions: a location information receiving unit 101, a transport instruction generating unit 102, and a transport instruction transmitting unit 103. The location information receiving unit 101 communicates with each cart 12 and is capable of receiving the coordinates of the cart's current location (cart position information). The transport instruction generating unit 102 is capable of generating transport instructions for the mobile robots 11 based on a given transport task. In addition to conventional "transport tasks based on specified locations," the transport instruction generating unit 102 can also accept "transport tasks based on specified individual carts." The transport instruction transmitting unit 103 is capable of communicating with the mobile robots 11 and transmitting transport instructions to the mobile robots 11.

The management device 10 can be configured as a general-purpose computer system equipped with, for example, a processor (CPU), memory, large-capacity storage, a wireless communication module, etc. In this case, each function of the management device 10 is realized by loading a program stored in the large-capacity storage into memory and executing it with the processor. However, this configuration is not limited to this, and some or all of the functions of the management device 10 may be realized by circuits such as FPGAs or ASICs, or some or all of the functions of the management device 10 may be executed by a cloud server or other external device. Alternatively, some or all of the functions of the management device 10 may be realized by computer resources installed on the mobile robot 11. The management device 10 may be configured as a single device or multiple devices.

The mobile robot 11 is an AMR used to transport the cart 12, and its main components include a drive unit with an electric motor, a battery, various sensors, a control unit, and a cart holding mechanism. The mobile robot 11 estimates its own position based on measurement results from sensors such as a laser scanner, LiDAR, or camera, as well as a pre-stored map, and determines the route to its destination to travel autonomously. The technology that uses sensors to estimate its own position and create maps is called SLAM (Simultaneous Localization and Mapping).

The mobile robot 11 in this embodiment has the following main functions: a transport instruction receiving unit 110 and a transport operation executing unit 111. The transport instruction receiving unit 110 communicates with the management device 10 and is capable of receiving transport instructions issued by the management device 10. The transport operation executing unit 111 controls the drive unit of the mobile robot 11 in accordance with the transport instructions, causing the mobile robot 11 to perform transport operations (i.e., picking up, transferring, and dropping off the cart 12). These functions are performed by the control unit of the mobile robot 11. The control unit may be configured as a computer having a processor and memory. In this case, the above functions are realized by the processor executing a program. Alternatively, the control unit may be configured as a circuit such as an ASIC or FPGA.

The cart 12 is a platform for carrying goods or people. The cart 12 of this embodiment is equipped with a positioning device 120. The positioning device 120 has a positioning unit 121 for measuring the current position of the cart 12, and a position information transmitting unit 122 for transmitting position information obtained by the positioning unit 121 to the management device 10. The specific configuration and positioning method of the positioning unit 121 will be described later.

The management device 10, mobile robot 11, and cart 12 (positioning device 120) can send and receive data to and from each other using wireless communication such as Wi-Fi.

(Cart transport process)
FIG. 3 shows an example of the flow of the cart transport process by the transport system 1.

The transportation system 1 executes cart transportation processing according to transportation tasks. Transportation tasks may be input by a user, generated by the management device 10 itself based on a production plan, or provided by an external system. The management device 10 registers the received transportation tasks in a queue (also called a task list) and processes each task according to a predetermined priority. The flow shown in Figure 3 shows the operations of the management device 10, the mobile robot 11, and the cart 12's positioning device 120 for one transportation task.

In step SA10, the transport instruction generation unit 102 of the management device 10 selects one transport task to be processed from the queue. Here, as an example of a "transport task based on the specification of an individual cart," the transport task "transport cart #c1 to position (x2, y2)" is selected, and the subsequent operation will be explained. Note that "cart #c1" means "a cart with cart ID c1." If the transport task includes the specification of an individual cart, the transport instruction generation unit 102 collects the position information of the individual cart using the position information receiving unit 101. Specifically, the position information receiving unit 101 sends a request for cart position information to the positioning device 120 of cart #c1 (step SA11).

When the positioning device 120 of cart #c1 receives a request for cart position information, the positioning unit 121 measures the current position (step SC10). Then, the position information transmission unit 122 transmits the measured coordinates (x1, y1) to the management device 10 as cart position information (step SC11). Note that while an example has been shown here in which positioning and notification of position information are performed in response to a request from the management device 10, the cart 12 may also perform positioning and transmit position information continuously (e.g., once per second), and the management device 10 may also constantly update the current position of each cart 12.

The location information receiver 101 of the management device 10 passes the current location information (x1, y1) of cart #c1 to the transport instruction generator 102, which then generates a transport instruction based on the transport task and the current location information of cart #c1 (step SA12). The transport instruction is a command for the mobile robot 11 to execute a transport operation and includes at least information on the pickup location where the cart to be transported should be picked up and the drop-off location where the cart to be transported should be dropped off, such as "pickup: (x1, y1) ⇒ drop-off: (x2, y2)." While a transport task can be specified using information identifying the individual cart 12 (cart ID), the transport instruction sent to the mobile robot 11 must explicitly specify the pickup and drop-off locations. In other words, the transport instruction generator 102 uses the location information of the cart 12 detected by positioning to convert the "specification of the individual cart" in the transport task into "specification of location coordinates."

The transport instruction sending unit 103 of the management device 10 then sends the transport instruction generated in step SA13 to the mobile robot 11 (step SA13). If there are multiple mobile robots 11, the management device 10 may select a mobile robot 11 to which to send the transport instruction, taking into consideration the status of each mobile robot 11 and future transport schedules, in order to maximize overall transport efficiency.

When the transport instruction receiving unit 110 of the mobile robot 11 receives a transport instruction, the transport operation executing unit 111 controls the mobile robot 11 in accordance with the transport instruction to perform the transport operation.

A specific example of a transfer operation will be described with reference to Figures 3 and 4. Figure 4 is a top plan view of the transfer area. Assume that the mobile robot 11 receives a transfer command at position (x0, y0). The transfer operation execution unit 111 first moves the mobile robot 11 from position (x0, y0) toward the pickup position (x1, y1) (step SB10). Upon arrival at the pickup position (x1, y1), the transfer operation execution unit 111 activates the cart holding mechanism to connect the mobile robot 11 and the cart 12 (step SB11). Various configurations of the cart holding mechanism are conceivable, including a mechanically engaging mechanism, a gripping mechanism using a hand, or a magnetic or air-based adsorption mechanism. Any configuration may be used. Next, the transport operation execution unit 111 moves the mobile robot 11 toward the drop-off position (x2, y2) (step SB12), and upon arrival at the drop-off position (x2, y2), releases the connection to the cart 12 (step S13). Through the above transport operation, the transport target cart 12 can be moved to the destination position (x2, y2).

(Another example of a transport task)
The following describes the operation when a transport task is selected in step SA10: "Transport the transport target cart located at position (x1, y1) to the side of cart #c2." In this case, the position information receiving unit 101 requests cart position information from the positioning device 120 of cart #c2 (step SA11) and acquires the position information of cart #c2 (steps SC10, SC11, and SA12). The transport instruction generating unit 102 then generates a transport instruction based on the transport task and the current position information of cart #c2 (step SA13). Specifically, the transport instruction generating unit 102 calculates a drop-off position for the transport target cart based on the position (x2, y2) of cart #c2. For example, if the size of the cart is w × w and the margin to prevent cart interference is m, setting the drop-off position as (x2 + w + m, y2) would result in cart #c2 and the transport target cart being positioned side-by-side, separated by a width m.

The following describes the operation when a transport task with the content "Transport cart #c1 to next to cart #c2" is selected in step SA10. In this case, the position information receiving unit 101 requests cart position information from the positioning devices 120 of cart #c1 and cart #c2 (step SA11) and acquires the position information of cart #c1 and cart #c2 (steps SC10, SC11, SA12). The transport instruction generating unit 102 then generates a transport instruction based on the transport task and the current position information of cart #c1 and cart #c2 (step SA13). Specifically, the transport instruction generating unit 102 sets the position (x1, y1) of cart #c1 as the pickup position, while calculating a position where the cart to be transported can be dropped off based on the position (x2, y2) of cart #c2. For example, if the size of the cart is w x w and the margin to prevent interference between carts is m, then by setting the drop-off position as (x2 + w + m, y2), cart #c2 and cart #c1 to be transported will be placed side-by-side, separated by a width m.

(Example of cart position detection configuration)
Next, a configuration example of cart position detection in the transport system 1 will be described.

5 shows an example of a configuration using GPS (Global Positioning System) positioning. The positioning device 120 of the cart 12 has a positioning unit 121 made up of a GPS sensor. The positioning unit 121 calculates the position (latitude, longitude) of the cart 12 by receiving GPS signals emitted from multiple GPS satellites 50. Note that, indoors where it is difficult to receive GPS signals, an indoor GPS transmitter 51 such as an IMES (Indoor Messaging System) may be used as a supplementary device.

FIG. 6 is a plan view showing an example configuration using Wi-Fi positioning. Wireless LAN access points 60 are installed at multiple locations within the transport area, and the positioning device 120 of the cart 12 is equipped with a positioning unit 121 consisting of a wireless communication module. The positioning unit 121 receives radio waves from multiple surrounding access points 60, estimates the distance to each access point 60 based on the received radio wave strength (RSSI), and calculates the cart's own position using three-point positioning. Note that BLE (Bluetooth Low Energy) beacons may be used instead of wireless LAN access points. That is, BLE beacons are installed at multiple locations within the transport area, the positioning unit 121 of the cart 12 receives beacon signals, and the cart's own position is estimated based on the received radio wave strength. Note that while Wi-Fi positioning and BLE beacon positioning are methods of measuring the distance between a fixed station and a mobile object based on the received radio wave strength, a method of measuring the distance between a fixed station and a mobile object based on the signal arrival time from the fixed station to the mobile object may also be used. The latter includes, for example, a positioning method that uses an impulse UWB (Ultra Wide Band) system.

The configuration shown in Figures 5 and 6 is one in which the positioning device 120 is provided on the cart 12 itself (i.e., on the mobile body side). In this configuration, the cart position detection function is realized by combining the positioning device 120 mounted on each cart 12 and the position information receiving unit 101 that receives position information from the positioning device 120 of each cart 12.

In another configuration example, a positioning means can be provided on the management device 10 side (i.e., the fixed station side). For example, in the configuration example shown in Figure 7, each cart 12 is equipped with a beacon 70 as an identification information transmitting device. Receivers 71 are installed at multiple locations within the transport area, and a positioning unit 72 is provided as a function of the management device 10. The cart identification information transmitted from the beacon 70 is received by multiple receivers 71 located near the cart 12. The distance between the cart 12 and each receiver 71 is estimated based on the received radio wave strength (RSSI) at each receiver 71, and the position of the cart 12 is calculated using three-point positioning. In this configuration, the cart position detection function is realized by the combination of the beacon 70, multiple receivers 71, and positioning unit 72. Alternatively, instead of measuring distance using received radio wave strength (RSSI), a method may be used in which the direction of arrival (AoA: Angle of Arrival) of radio waves is estimated based on the phase of the radio waves, and the position of the cart 12 is estimated from the angle measurement results at the multiple receivers 71.

5 to 7 show examples of cart position detection configurations, but these are merely examples, and other positioning methods may be used. For example, a method such as Pedestrian Dead Reckoning (PDR) may be used, in which the self-position is recognized by sequentially recording the direction and amount of movement of the cart 12 using detection results from multiple sensors such as a barometric pressure sensor, a geomagnetic sensor, an acceleration sensor, and a gyroscope.

Second Embodiment
In the first embodiment, we assumed a configuration in which the mobile robot 11 can hold the cart 12 from any direction. In this case, there is no need to be particularly concerned about the angle θ when the mobile robot 11 picks up or drops off the cart 12. However, depending on the structure of the cart holding mechanism of the mobile robot 11, there may be cases in which the angle θ of the mobile robot 11 must be adjusted to match the orientation of the cart 12. In the second embodiment, we present a solution to the latter case.

The simplest solution is to determine the angle θ when placing the cart 12 by an operational rule.
For example, a rule may be established that the cart 12 must be placed at a predetermined angle θ = xxx [deg], as shown in the plan view of FIG. 8A , or that the cart 12 must be placed with its back facing the wall, as shown in the plan view of FIG. 8B (note that the arrow drawn inside the cart 12 in FIGS. 8A and 8B indicates the forward direction of the cart 12). If the mobile robot 11 or the worker thoroughly orients the cart 12 so that the angle θ is as determined by the rule, the mobile robot 11 can approach the cart 12 from a direction that allows it to pick up the cart 12 when heading to the pick-up position.

The mobile robot 11 or the cart 12 may be equipped with a function for detecting the orientation of the cart 12. For example, the mobile robot 11 may measure the orientation of the cart 12 using a sensor such as a laser scanner or LiDAR. Alternatively, the mobile robot 11 may capture an image of the cart 12 with an imaging device (camera) and estimate the orientation of the cart 12 through image processing. Alternatively, as shown in FIG. 9A , a direction sensor (compass) 90 may be provided in the positioning device 120 of the cart 12, and the direction sensor 90 may acquire the orientation of the cart 12. Alternatively, as shown in FIG. 9B , the positioning device 120 of the cart 12 may be provided with multiple positioning units 121 and cart position information generators 123, and the cart position information generators 123 may calculate the position coordinates (x, y) and angle θ of the cart 12 based on the position information measured by each positioning unit 121. For example, if position information (x1, y1) and (x2, y2) is obtained from two positioning units 121 installed at both ends of the cart 12, the position coordinates (x, y) and angle θ can be calculated using the following formula.
x=(x1+x2)/2
y=(y1+y2)/2
θ=arctan((y2-y1)/(x2-x1))

A mechanism may be provided to automatically adjust the posture of the mobile robot 11 and cart 12. For example, a protrusion may be provided on either the mobile robot 11 or the cart 12, and a guide shaped to guide the protrusion may be provided on the other. Alternatively, the posture of the cart 12 may be determined by catching it with an electric latch mechanism.

In this embodiment, the transport instruction generator 102 may include in the transport instruction the angle θ1 (i.e., information indicating the orientation of the target cart 12) at which the mobile robot 11 picks up the target cart 12, such as "Pickup: (x1, y1, θ1) ⇒ Drop-off: (x2, y2)." This allows the mobile robot 11 to approach the target cart 12 from a direction that allows it to pick it up.

The transport instruction generation unit 102 may also include in the transport instruction the angle θ2 (i.e., information indicating the orientation of the target cart 12) at which the mobile robot 11 drops off the target cart 12, such as "Pickup: (x1, y1, θ1) ⇒ Drop-off: (x2, y2, θ2)." This makes it possible to place the cart 12 at the drop-off point in the desired orientation.

Third Embodiment
In the first embodiment, positioning is always performed regardless of whether the cart 12 is moving or stationary, whereas in the third embodiment, the power consumption of the positioning device 120 is reduced by changing the frequency of positioning depending on the running state of the cart 12.

Figure 10 is a diagram showing a schematic configuration example of a transport system according to the third embodiment. The following description will focus on the components that differ from the first embodiment.

The management device 10 of this embodiment has the following main functions: a location information receiving unit 101, a transport instruction generating unit 102, a transport instruction transmitting unit 103, and a location information storage unit 104. The location information receiving unit 101 communicates with each cart 12 and collects cart location information. The location information storage unit 104 is a storage means that stores the latest location information of each cart collected by the location information receiving unit 101.

The positioning device 120 of the cart 12 has a positioning unit 121, a position information transmission unit 122, and a running state detection unit 124. The running state detection unit 124 has a function that can detect the running state of the cart 12. For example, an inertial measurement unit (IMU) may be used to detect whether the cart 12 is stationary or moving, or encoders attached to the wheels may be used to detect wheel rotation.

FIG. 11 shows an example of the operation of the positioning device 120 in the third embodiment. The positioning device 120 monitors the state of the cart 12 using the traveling state detection unit 124. When the cart 12 remains stationary or is moving (step SC30: NO), the positioning device 120 puts the positioning unit 121 and the position information transmission unit 122 into a sleep state (step SC31) to reduce power consumption. When the traveling state detection unit 124 detects that the cart 12 has transitioned from a moving state to a stopped state (step SC30: YES), the positioning device 120 measures the position where the cart 12 has stopped using the positioning unit 121 (step SC32) and transmits the position information to the management device 10 using the position information transmission unit 122 (step SC33). When the position information receiving unit 101 receives new position information from the cart 12 (step SA30), the management device 10 updates the position information of the cart 12 recorded in the position information storage unit 104 (step SA31). This mechanism ensures that the latest stopping position of each cart is always stored in the position information storage unit 104. Therefore, when the transport instruction generation unit 102 generates a transport instruction from a transport task, it only needs to obtain the position information of each individual cart from the position information storage unit 104.

In this embodiment, the power consumption of the positioning device 120 can be reduced by changing the frequency of positioning depending on the traveling state of the cart 12. For example, positioning is not performed when the cart 12 is stationary or moving, and positioning is performed only when the cart 12 transitions from a moving state to a stationary state. Note that in this embodiment, positioning is stopped when the cart 12 is moving. However, for example, control may be performed such that positioning is performed when the cart 12 is moving, and positioning is stopped or the frequency of positioning is reduced after the cart 12 transitions to a stationary state. Alternatively, the frequency of positioning may be changed depending on the traveling speed of the cart 12 (for example, the faster the speed, the more frequently the positioning is performed). In any case, changing the frequency of positioning depending on the traveling state of the cart 12 reduces unnecessary positioning, thereby reducing the power consumption of the positioning device 120.

In this embodiment, a configuration in which the positioning device 120 is mounted on the cart 12 is illustrated, but a similar power-saving function may also be applied to a configuration in which the cart 12 is mounted on the identification information transmission device 70 (see Figure 7). In that case, the identification information transmission device 70 may be provided with a driving state detection unit that detects the driving state of the cart 12, and the frequency of transmission of the cart identification information may be changed depending on the driving state of the cart 12. This makes it possible to reduce the power consumption of the identification information transmission device 70.

Fourth Embodiment
After the mobile robot 11 starts a transport operation in accordance with a transport command, the location of the cart to be transported may change for some reason, or another cart may be placed at the intended drop-off location of the cart to be transported. In particular, in a workplace where workers and the mobile robot 11 work together, the workers themselves move the carts, making the above-mentioned situations more likely to occur.

Therefore, in the fourth embodiment, even after the mobile robot 11 starts the transport operation, it monitors the position of the cart to be transported and the status of the drop-off location, and controls the transport operation to change or stop as necessary.

Figure 12 is a flowchart showing an example of the pickup operation change process and drop-off operation change process performed by the management device 10.

After the management device 10 sends a transport instruction to the mobile robot 11 (step SA40), it periodically obtains the position information of the cart 12 to be transported and monitors whether the position of the cart 12 has changed (step SA41). If the position of the cart 12 to be transported changes before the mobile robot 11 picks it up (step SA41: YES), the management device 10 instructs the mobile robot 11 to change the pickup position of the cart 12 to be transported (step SA42). After receiving a notification from the mobile robot 11 that the cart 12 to be transported was successfully picked up (step SA43), the management device 10 proceeds to step SA44.

In step SA44, the management device 10 acquires the location information of carts other than the cart 12 to be transported and checks whether any other carts are placed at the location where the cart 12 to be transported is to be dropped off. If another cart is placed at the drop-off location before the mobile robot 11 transports the cart 12 to be transported to the drop-off location (step SA44: YES), the management device 10 instructs the mobile robot 11 to change the drop-off location of the cart 12 to be transported (step SA45). For example, the management device 10 may calculate the coordinates of the adjacent location of the other cart and use those coordinates as the new drop-off location. When the management device 10 receives a notification from the mobile robot 11 that the cart 12 to be transported has been successfully dropped off (step SA46), the transport operation is completed.

The control described above allows the transport operation to continue safely, even if the location of the cart to be transported changes or if another cart is placed at the location where the cart to be transported is scheduled to be dropped off. The pickup and drop-off positions are automatically corrected, allowing the transport operation to continue safely. While the flow in Figure 12 instructs a change in the pickup and drop-off positions, the transport operation may also be stopped if the location of the cart to be transported changes or if it is detected that another cart is at the drop-off position. For example, the operation of the mobile robot 11 may be stopped, an error may be notified to the operator, and the transport operation of the mobile robot 11 may be resumed after the cause of the error is corrected.

Fifth Embodiment
The fifth embodiment is configured to provide a generator on the cart 12. Specifically, as shown in FIG. 13 , generators 131 are attached to wheels (casters) 130 of the cart 12. When the wheels 130 rotate as the cart 12 moves, an electromotive force is generated in the generator 131. By configuring the positioning device 120 or the identification information transmission device 70 to operate with the power output from the generator 131, a battery is not required, thereby enabling the positioning device 120 and the identification information transmission device 70 to be made smaller and at a lower cost. For example, the positioning device 120 and the identification information transmission device 70 may be made smaller and built into the wheels 130 of the cart 12 together with the generator 131.

Sixth Embodiment
In the first embodiment, the management device 10 has the function of acquiring location information from the cart 12 (the location information receiving unit 101). In the sixth embodiment, however, the mobile robot 11 has a similar function.

Figure 14 is a diagram showing a schematic configuration example of a transport system according to the sixth embodiment. The following description will focus on the components that differ from the first embodiment.

The management device 10 of this embodiment has a transport task transmitter 105 as its main function. The mobile robot 11 has a transport task receiver 112, a location information receiver 113, a transport instruction generator 114, a transport instruction receiver 110, and a transport operation execution unit 111. The transport task receiver 112, the location information receiver 113, and the transport instruction generator 114 may be built into the mobile robot 11, or may be configured as external devices connectable to the mobile robot 11.

Figure 15 shows an example of the flow of the cart transport process in this embodiment.

In step SA60, the transport task sending unit 105 of the management device 10 selects one transport task to be processed from the queue and sends that transport task to the mobile robot 11. Here, as an example of a "transport task based on the specification of an individual cart," the transport task "Transport cart #c1 to position (x2, y2)" is selected, and the subsequent operation will be explained.

When the transport task receiving unit 112 of the mobile robot 11 receives a transport task from the management device 10, it passes it to the transport instruction generating unit 114 (step SB60). If the transport task includes the specification of an individual cart, the transport instruction generating unit 114 collects the position information of the individual cart using the position information receiving unit 113. Specifically, the position information receiving unit 113 sends a request for cart position information to the positioning device 120 of cart #c1 (step SB61).

When the positioning device 120 of cart #c1 receives the request for cart position information, the positioning unit 121 measures the current position (step SC60). Then, the position information transmission unit 122 transmits the measured coordinates (x1, y1) as cart position information to the mobile robot 11 (step SC61).

The location information receiver 113 of the mobile robot 11 passes the current location information (x1, y1) of cart #c1 to the transport instruction generator 114, which then generates a transport instruction based on the transport task and the current location information of cart #c1 (step SB62). The subsequent processing is the same as in the first embodiment, so a detailed description will be omitted.

Figure 16 shows a modified version of the transport system of the sixth embodiment, in which the power-saving function described in the third embodiment is applied to the transport system of the sixth embodiment. That is, a traveling state detection unit 124 is provided in the positioning device 120 of the cart 12, and positioning is performed, for example, when the cart 12 transitions from a moving state to a stationary state, and the position information is notified to the mobile robot 11. When the mobile robot 11 receives the position information via the position information receiving unit 113, it updates the position information of the cart 12 recorded in the position information storage unit 115. With this configuration, it is possible to reduce power consumption, as in the third embodiment.

Seventh Embodiment
In the fourth embodiment, the cart position detection function detects the presence of another cart at the drop-off location and changes the drop-off operation accordingly. In contrast, in the seventh embodiment, the mobile robot 11 itself checks whether there is space available to place the cart 12.

Specifically, the mobile robot 11 follows the transport instruction to pick up the cart 12 to be transported, moves to the drop-off location (or just before it), and checks whether there is enough space to place the cart 12 at the drop-off location. For example, the mobile robot 11 uses sensors such as a laser scanner or LiDAR, or cameras or stereo vision, to detect obstacles at and around the drop-off location. If no obstacles are present, the mobile robot 11 simply drops off the cart 12 according to the transport instruction. On the other hand, if an obstacle is present, the mobile robot 11 stops the transport operation and notifies the management device 10 or an operator that the cart 12 failed to be dropped off.

Alternatively, the mobile robot 11 may change the location where the cart 12 is dropped off according to predetermined rules. Examples of rule bases are shown in Figures 17A and 17B. In the example of Figure 17A, the cart placement area is pre-divided, and a priority order is set for each section. In the example of Figure 17B, the cart placement area is divided into a grid pattern, and the rule is to fill the carts starting from the far left. In either case, the mobile robot 11 simply drops off the cart 12 at the highest priority location among the available sections.

<Others>
The above-described embodiments merely illustrate exemplary configurations of the present invention. The present invention is not limited to the specific embodiments described above, and various modifications are possible within the scope of the technical concept. For example, the structures of the mobile robot and cart are not limited to those shown in the drawings, and any shape or structure may be used.

<Additional Notes>
(1) Cart position detection means (120, 101) for detecting the position of each of a plurality of carts (12) that may be transported;
a transport instruction generating means (102) for generating transport instructions including information on a pick-up position for picking up the transport target cart (12) and information on a drop-off position for dropping off the transport target cart (12) based on the position of each cart (12) detected by the cart position detecting means (120, 101);
a self-propelled transport device (11) that transports a cart (12) present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generating means (102);
A transport system (1) comprising:

1: Transport system 10: Management device 11: Mobile robot (self-propelled transport device)
12: Cart

Claims (15)

a cart position detection means for detecting the position of each of a plurality of carts that may be transported;
a transport instruction generating means for generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting means;
a self-propelled transport device that transports a cart present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generating means;
and
The cart position detection means includes a positioning device mounted on each cart, and a position information receiving means for receiving, from each cart, the position information measured by the positioning device.
A transport system characterized by: The positioning device has a running state detection means for detecting the running state of the cart, and changes the frequency of positioning in accordance with the running state detected by the running state detection means.
2. The transport system according to claim 1. The positioning device has a generator that generates electricity through the rotation of the wheels of the cart and operates using the power of the generator.
3. The transport system according to claim 1 or 2. a cart position detection means for detecting the position of each of a plurality of carts that may be transported;
a transport instruction generating means for generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting means;
a self-propelled transport device that transports a cart present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generating means;
and
The cart position detection means includes an identification information transmission device mounted on each cart, a plurality of receiving devices for receiving signals transmitted from the identification information transmission device, and a plurality of receiving devices for receiving signals transmitted by the plurality of receiving devices.
and positioning means for calculating the position of each cart based on the received signal strength.
A transport system characterized by: The identification information transmission device has a running state detection means for detecting the running state of the cart, and changes the frequency of transmission according to the running state detected by the running state detection means.
5. The transport system according to claim 4. The identification information transmission device has a generator that generates electricity by rotating the wheels of the cart and operates using the power of the generator.
6. The transport system according to claim 4 or 5. The transport instruction generating means
Accept a transport task to transport a first cart to a first location;
The conveying system according to any one of claims 1 to 6, characterized in that a conveying instruction is generated in which the position of the first cart detected by the cart position detection means is set as a pick-up position and the first position is set as a drop-off position. The transport instruction generating means
Accepting a transport task to transport a cart located at a second position to a position adjacent to a second cart;
calculating a third position at which the transport target cart can be dropped off based on the position of the second cart detected by the cart position detection means;
The transport system according to any one of claims 1 to 6 , characterized in that a transport instruction is generated in which the second position is a pick-up position and the third position is a drop-off position. The transport instruction generating means
Accepting a transport task to transport the third cart to a location adjacent to the fourth cart;
calculating a fourth position at which the transport target cart can be dropped off based on the position of the fourth cart detected by the cart position detection means;
The conveying system according to any one of claims 1 to 6, characterized in that a conveying instruction is generated in which the position of the third cart detected by the cart position detection means is set as a pick-up position and the fourth position is set as a drop-off position. The transport system according to any one of claims 1 to 9 , characterized in that the transport instruction generation means further includes information indicating the orientation of the transport target cart when picking up the transport target cart in the transport instruction. A transport system as described in any one of claims 1 to 10 , characterized in that the transport instruction generation means further includes information indicating the orientation of the transport target cart when the transport target cart is dropped off in the transport instruction. a cart position detection means for detecting the position of each of a plurality of carts that may be transported;
a transport instruction generating means for generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting means;
a self-propelled transport device that transports a cart present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generating means;
A transport system characterized by having a pickup operation change means that changes the pickup position of the cart to be transported or stops transporting the cart if the position of the cart to be transported changes before the self-propelled transport device picks up the cart to be transported . a cart position detection means for detecting the position of each of a plurality of carts that may be transported;
a transport instruction generating means for generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting means;
a self-propelled transport device that transports a cart present at the pickup position to the drop-off position in accordance with the transport instruction generated by the transport instruction generating means;
A transport system characterized by having a drop-off operation change means that changes the location at which the transport target cart is dropped off or stops transporting the cart if another cart is placed at the drop-off position before the self-propelled transport device transports the transport target cart to the drop-off position. a cart position detection step of detecting the position of each of a plurality of carts by receiving, from each cart, position information measured by a positioning device mounted on each of the plurality of carts that may be transported;
a transport instruction generating step of generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting step;
a step of causing a self-propelled conveying device to execute a conveying operation of conveying the cart present at the pick-up position to the drop-off position in accordance with the conveying instruction generated by the conveying instruction generating step;
A method for controlling a transport system, comprising: a cart position detection step of detecting the position of each of the carts by receiving, by a plurality of receiving devices, signals transmitted from identification information transmitting devices mounted on each of the carts that may be transported, and calculating the position of each cart based on the strength of the signals received by the plurality of receiving devices;
a transport instruction generating step of generating transport instructions including information on a pick-up position for picking up a transport target cart and information on a drop-off position for dropping off the transport target cart based on the position of each cart detected by the cart position detecting step;
a step of causing a self-propelled conveying device to execute a conveying operation of conveying the cart present at the pick-up position to the drop-off position in accordance with the conveying instruction generated by the conveying instruction generating step;
A method for controlling a transport system, comprising: