Travel control system for transport vehicle and travel control method for transport vehicle

Abstract

[Problem] To provide a travel control system for a transport vehicle and a travel control method for a transport vehicle that can be used to attain both higher stopping precision and better travel efficiency. [Solution] A control system for a transport vehicle according to the present disclosure is a travel control system for a transport vehicle, characterized by comprising a control unit that determines whether or not the distance d from a current position to a destination position is a predetermined value or less, and upon determining that the distance d is the predetermined value or less, controls the travel velocity of the transport vehicle such that the relation of the distance d, the travel velocity v, and a constant k satisfies expression [A].　[A]: v = sqrt(2*k*d)

Description

Transport vehicle travel control system and transport vehicle travel control method

[0001] The present disclosure relates to a travel control system and a travel control method for a guided vehicle.

[0002] In recent years, automated guided vehicles capable of autonomous travel have been put to practical use for transporting cargo within facilities such as factories and warehouses. For example, there are known guided vehicles that travel along predetermined guidelines laid out within the facility, autonomous travel without guidelines, or a combination of these. Patent Document 1 proposes a technology for driving a guided vehicle to a destination by setting a travel speed for each section of a travel route.

[0003] JP 2012-053837 A

[0004] The technology described in Patent Document 1 discloses that when a transport vehicle travels along a line, it travels at a set speed of either first to fourth speed or creep speed. However, there is room for improvement in terms of achieving both improved stopping accuracy and improved travel efficiency.

[0005] Therefore, the present disclosure has been made in consideration of at least one of the above problems, and its purpose is to provide a transport vehicle travel control system and a transport vehicle travel control method that can achieve both improved stopping accuracy and improved travel efficiency.

[0006] According to the present disclosure, there is provided a travel control system for a transport vehicle, comprising: a control unit that determines whether a distance d from a current position to a destination position is equal to or less than a predetermined value; and, when it is determined that the distance d is equal to or less than the predetermined value, controls the travel speed of the transport vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies equation [A]: v = sqrt(2*k*d) [A].

[0007] According to the present disclosure, there is provided a travel control method for a transport vehicle, characterized in that a control unit determines whether a distance d from a current position to a destination position is equal to or less than a predetermined value, and when it is determined that the distance d is equal to or less than the predetermined value, controls the travel speed of the transport vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies equation [A]: v = sqrt(2*k*d) [A].

[0008] According to the present disclosure, it is possible to provide a transport vehicle travel control system and a transport vehicle travel control method that can achieve both improved stopping accuracy and improved travel efficiency.

[0009] FIG. 1 is a perspective view showing an example of the hardware configuration of a transport vehicle according to the present embodiment; FIG. 2 is a bottom view showing an example of the hardware configuration of a transport vehicle according to the present embodiment; FIG. 3 is a diagram showing an example of the hardware configuration when a transport vehicle according to the present embodiment and a towing carriage are coupled; FIG. 4 is a diagram showing another example of the hardware configuration when a transport vehicle according to the present embodiment and a towing carriage are coupled; FIG. 5 is a diagram showing an example of the configuration of an operation area according to the present embodiment; FIG. 6 is a diagram showing the positional relationship between a guide line and the transport vehicle when a two-dimensional code constituting the guide line is detected by a guide line detection unit; FIG. 7 is a bottom view showing the positional relationship between a guide line and the transport vehicle when a magnetic tape constituting the guide line is detected by a guide line detection unit; FIG. 8 is a diagram showing an example of the overall configuration of a transport system according to the present embodiment; FIG. 9 is a diagram showing the configuration of an integrated control device according to the present embodiment; FIG. 10 is a diagram showing the functional configuration of a transport vehicle according to the present embodiment; FIG. 11 is a diagram showing an example of the movement speed of a transport vehicle according to the present embodiment based on a travel distance; FIG. 12 is a diagram showing an example of the movement speed of a transport vehicle according to the present embodiment based on time; FIG. 13 is a diagram showing an example of the movement speed of a transport vehicle as a comparative example based on a travel distance; FIG. 14 is a diagram showing an example of the movement speed of a transport vehicle as a comparative example based on time; FIG. 15 is a diagram showing the control flow of a control system according to the present embodiment.

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0011] In logistics warehouses, manufacturing plants, and the like, it is necessary to stop transported objects such as guided vehicles, carts, and pallets at a predetermined position and orientation in a predetermined manner in order to coordinate with on-site operations. For example, it is necessary to transport the objects so that workers can retrieve the items placed on the transported objects without moving, by stopping the cart at a position that is coordinated with the belt conveyor or by parking it next to the worker's work position. Coordinating with the belt conveyor or parking it next to the worker's work position as described above requires highly accurate transport operations. Furthermore, simply slowing the speed to improve the accuracy of the stopping position reduces transport efficiency. Furthermore, when transporting relatively heavy objects, large inertial forces are applied to the guided vehicle, making it difficult to manage the speed and therefore difficult to stop it at the intended position.

[0012] The hardware configuration of the transport vehicle and the towed carriage will be described using Figures 1 to 4. Figure 1 is a perspective view showing an example of the hardware configuration of the transport vehicle according to this embodiment. The transport vehicle in this example is an unmanned transport vehicle, but the system can also be applied to various vehicles that people can ride in. Arrow 15 in Figure 1 indicates the direction of travel of the transport vehicle. As shown in Figure 1, the transport vehicle is equipped with a coupling unit 11 for switching between coupled and uncoupled states with the carriage, an object position detection unit 12 for detecting objects around the transport vehicle, drive wheels 13, and non-drive wheels 14.

[0013] Additionally, a connecting unit 11 and an object position detection unit 12 are mounted on the top surface of the transport vehicle. The connecting unit 11 is configured, for example, by an actuator, and is configured such that when connecting to a carriage, the actuator extends upward to connect to a connecting receiving portion (not shown) on the carriage, and when disconnecting, the actuator retracts to disconnect the connecting unit from the connecting receiving portion on the carriage. Furthermore, the connecting units 11 are arranged at four positions surrounding the drive wheels 13 of the transport vehicle on a plane, and can be connected to the carriage at five positions. In this embodiment, an example having four connecting units will be described, but the number of connecting units does not necessarily have to be five, and any number greater than one can be selected.

[0014] The object position detection unit 12 is a device that detects the distance from the transport vehicle to an object. Examples of the object position detection unit 12 include a laser distance sensor (such as LiDAR (Light detection and ranging)) that measures the distance and direction to an object by emitting laser light and measuring the time it takes for the light to hit the object and bounce back; a millimeter-wave radar that detects the distance to an object based on a millimeter-wave transmission signal and a received signal that is reflected off the object; and a camera-type distance sensor that measures the distance to an object by photographing the object with a camera and analyzing the photographed image. In this embodiment, the object position detection unit 12 is disposed on the top surface of the transport vehicle at the front in the traveling direction. However, instead, the object position detection unit 12 may be disposed on the front side in the traveling direction. Furthermore, the object position detection unit 12 may be disposed not only at the front but also at the rear side or both left and right sides in the traveling direction.

[0015] The object position detection unit 12 may be configured to detect objects in a 360-degree range around the transport vehicle, but is configured to be able to detect objects at least ahead in the traveling direction 15 of the transport vehicle.

[0016] FIG. 2 is a bottom view showing an example of the hardware configuration of a transport vehicle according to this embodiment. Drive wheels 13 are provided on the bottom of the transport vehicle at both the left and right sides of the transport vehicle's travel direction 15, and non-drive wheels 14 are provided in front of and behind each drive wheel 13. The drive wheels 13 are connected to the rotating shaft of a motor and driven, with the right and left drive wheels controlled independently. The controller controls the speed of the drive wheels to control the transport vehicle's speed. The controller also controls the rotation speed and direction of each drive wheel independently, enabling the transport vehicle to travel around curves and turn on the spot to change direction. The non-drive wheels 14 are not driven and rotate passively as the transport vehicle moves due to the drive wheels 13. The non-drive wheels 14 have, for example, forks that secure the wheels and axles, and the forks are composed of swivel casters rotatably connected to the bottom member of the transport vehicle. Therefore, the wheel rotation direction of the non-drive wheels 14 changes passively depending on the travel direction and rotation of the transport vehicle. Figure 2 illustrates an example of the hardware configuration of a transport vehicle with two drive wheels and four non-drive wheels at the four corners, but the present invention is not limited to this hardware configuration, and it is also possible to adopt a configuration with a total of four wheels, two drive wheels and two non-drive wheels, and it is also possible to adopt a configuration in which the front wheels are steerable in this four-wheel configuration.

[0017] A guide line detector 16 that detects the guide line is provided on the bottom of the transport vehicle. The guide line detector 16 is preferably provided further forward in the direction of travel of the transport vehicle than the drive wheels 13. This makes it easier for the transport vehicle to follow the guide line when traveling around a curved guide line, and also allows the transport vehicle and the towing cart to receive information from the guide line as soon as possible as they travel, thereby enabling them to quickly execute processing such as stopping. The guide line detector uses a sensor that corresponds to the type of guidance method as described above. If the guidance method is an electromagnetic induction method, a pickup coil is used as the sensor for the guide line detector; if the guidance method is a magnetic induction method, a magnetic sensor is used; and if the guidance method is an image recognition method, a camera is used.

[0018] 3 shows an example of the hardware configuration when the transport vehicle and towing dolly according to this embodiment are coupled, specifically showing an example in which the transport vehicle 10 is coupled to the dolly while sliding under the dolly to be towed. In this case, a mortar-shaped coupling receiver is disposed on the bottom of the dolly at a position corresponding to the conical coupling part 11, and the dolly can be coupled by extending the coupling part 11 upward, and can be released from the coupling to the dolly by retracting the coupling part 11.

[0019] FIG. 4 shows another example of a hardware configuration when a transport vehicle and a towing dolly according to this embodiment are coupled. In the example shown in FIG. 4 , the transport vehicle is coupled to the dolly while positioned next to the dolly. The dolly has a coupling receiving portion 2010 that couples with at least a portion of the coupling portion 11 of the transport vehicle. The dolly can be coupled to the dolly by extending the coupling portion 11 upward, and can be released from the dolly by retracting the coupling portion 11. In FIGS. 3 and 4 , an example is shown in which the coupling portion 11, which is formed by an actuator or the like and located on the top surface of the transport vehicle, is coupled to and released from the dolly by extending and retracting in the vertical direction. However, the coupling method between the transport vehicle and the dolly is not limited to this, and other coupling methods may also be used. Furthermore, the transported object coupled to the transport vehicle is not limited to a dolly, and may be, for example, a pallet or cabinet without wheels. When transporting a pallet or cabinet, the transport vehicle slides under the pallet or cabinet and couples the pallet or cabinet while lifting it up.

[0020] 5 is a diagram showing an example of the configuration of the operation area 130 according to this embodiment. As shown in FIG. 3, guide lines 131 are laid within the operation area 130. When a guided vehicle traveling in autonomous travel mode detects the guide lines 131 at a preset travel mode switching position 132, the travel control mode is switched from the autonomous travel mode to the guided travel mode. Conversely, when a guided vehicle traveling in guided travel mode on the guide lines enters the preset travel mode switching position 132, the travel control mode is switched from the guided travel mode to the autonomous travel mode. In order to guide the guided vehicle to a position close to a shelf where packages are stored, a conveyor belt, or a worker's work position, the track formed by the guide lines 131 is laid at a position close to the shelf or work position via multiple branch points.

[0021] A guided vehicle 10 traveling in an autonomous travel area where no guide lines are installed in autonomous travel mode changes its travel mode to a guided travel mode in which it follows the guide lines when it enters travel mode switching position 132 and detects a guide line 131. On the other hand, when a guided vehicle traveling in guided travel mode on a guide line enters travel mode switching position 132, the travel control mode is switched from the guided travel mode to the autonomous travel mode, and the guided vehicle leaves the guide line and starts autonomous travel.

[0022] As the guidance lines 111 and 131 shown in Fig. 5, guidance lines of various conventional guidance methods, as described below, can be applied. Specifically, for example, an electromagnetic induction method in which a pickup coil on the transport vehicle detects a magnetic field generated by passing a weak alternating current through a metal wire installed as a guidance line, a magnetic induction method in which a magnetic sensor on the transport vehicle reads a magnetic tape laid on the floor as a guidance line, or an image recognition method in which a camera on the transport vehicle takes an image of a code (such as a barcode or a two-dimensional code) laid on the floor as a guidance line and processes the image.

[0023] 6 shows the positional relationship between the guide line and the transport vehicle when the two-dimensional code constituting the guide line is detected by the guide line detection unit 16. The guide line is formed by printing a plurality of two-dimensional codes, each with code information printed on a two-dimensional plane, aligned in the direction of the guide line, as shown in two-dimensional code 1000. When the guide line detection unit 16 detects a two-dimensional code, it acquires the position information of the two-dimensional code based on the code information acquired from the two-dimensional code.

[0024] Fig. 7 shows the positional relationship between the guide line and the transport vehicle when the guide line detection unit 16 detects the magnetic tape that constitutes the guide line. The guide line detection unit 16 shown in Fig. 13 is configured to have a plurality of magnetic sensors 17 that detect the magnetic tape arranged laterally in the direction of travel of the transport vehicle. Each of the plurality of magnetic sensors 17 provided in the guide line detection unit 16 outputs a detection signal indicating whether or not the magnetic tape has been detected. In the case shown in Fig. 22, the three magnetic sensors 17A located in the center of the guide line detection unit 16 detect the magnetic tape, while the two magnetic sensors 17B on each side of the guide line detection unit 16 do not detect the magnetic tape.

[0025] <Configuration of the Transport System> Next, the configuration of the transport system of this embodiment will be described. Fig. 8 is a diagram showing an example of the overall configuration of the transport system according to this embodiment. The transport system 1000 includes a plurality of transport vehicles (10a, 10b), a carriage 2000 as a transported object, a control device 3000 capable of displaying the status of the transport vehicles or inputting commands to the transport vehicles, a general control device 4000 that manages information necessary for the operation of the transport vehicles, an input / output device 5000 that displays information from the general control device and inputs information to the general control device, and a communication network 6000 that communicably connects the plurality of transport vehicles (10a, 10b), the control device 3000, and the general control device 4000.

[0026] The transport system 1000 can also be connected to an external system 7000 via a communication network 6000. When the transport system 1000 is introduced into a manufacturing factory to transport parts required for manufacturing from a storage warehouse to a manufacturing line, the transport system 1000 performs inter-system cooperation with a manufacturing management system as the external system 7000. In this case, by obtaining information on the operational progress of manufacturing work from the manufacturing management system, the transport volume and transport route of the transport vehicle can be dynamically adjusted according to the progress of the manufacturing work.

[0027] As another example, when the conveyance system 1000 is introduced into a logistics warehouse, and when cargo is brought into the warehouse by truck or the like, the incoming cargo is transported from an inlet to a storage warehouse, and when cargo is shipped from the warehouse, the cargo to be shipped from the storage warehouse is transported to an outlet, the conveyance system 1000 performs inter-system cooperation with a logistics management system as an external system 7000. In this case, by obtaining information related to carrying in and shipping from the logistics management system, the transportation volume and transportation route by the transport vehicle can be changed.

[0028] In a facility where a transport system is installed, a plurality of transport vehicles (10a, 10b) are generally in operation, and each transport vehicle is communicably connected to other transport vehicles and other components via a communication network 6000. For example, the transport vehicle transmits various detection information detected by its own detection unit and other control information to the control device 3000, the overall control device 4000, and other transport vehicles 10. The transport vehicle 10 is also electrically connected to the cart 2000 or communicably connected via short-range communication means, and is configured to be able to receive information about the connection state and cart identification information from the cart.

[0029] The controller 3000 has a function to display status information of each transport vehicle and a function to input commands to a specified transport vehicle. For example, the status information of the transport vehicle displayed on the controller includes the identification information, position (coordinates, position on a map), speed, direction, driving history, charge level information of the battery mounted on the transport vehicle and serving as the power source for the transport vehicle, and identification information of the transported object such as a cart transported by the transport vehicle. Examples of commands input to the transport vehicle include command information regarding the destination (destination position) of the transport vehicle, operation commands to couple or uncouple from the cart, a command to start the transport vehicle, a command to stop the transport vehicle, and a command to return to the charging station.

[0030] 9 shows a configuration diagram of the overall control device 4000 in this embodiment. The overall control device 4000 has a status information recording unit 4010 that records status information of multiple guided vehicles operating in a facility area, an operation scenario management unit 4020 that manages operation scenarios of the multiple guided vehicles, a map management unit 4030 that generates and updates a map of the work area based on detection information of the guided vehicles including detection information of guide lines acquired by a guide line detection unit of the guided vehicles, an abnormality determination unit 4040 that determines abnormalities in the guide lines and the guided vehicles based on the detection information of the guided vehicles, and a communication unit 4050 that communicates with an external input / output device 5000 and a communication network 6000.

[0031] The status information of the guided vehicles recorded by the status information recording unit 4010 includes, for example, obstacle detection positions detected by the multiple guided vehicles in operation, guide line detection positions, history information of the travel positions of the guided vehicles, information on the battery charge level, identification information of the carriages connected to the multiple guided vehicles, operation modes of the multiple guided vehicles (guided travel mode or autonomous travel mode), various other detection information detected by the detection unit 230 of the guided vehicles, map information of the work area, etc. The operation scenario managed by the operation scenario management unit 4020 includes, for example, information on the destination of each of the multiple guided vehicles, the multiple operations to be performed until the vehicle reaches the destination, the operation sequence of the multiple operations, and switching conditions for the multiple operations.

[0032] The map management unit 4030 generates a map including the position information of obstacles and guide lines within the work area based on the historical information of the obstacle detection positions, guide line detection positions, and travel position of the guided vehicle detected by the guided vehicle. Furthermore, the map management unit 4030 updates the position information of guide lines registered in the map based on the information of the detected positions of guide lines accumulated by one or more guided vehicles.

[0033] The abnormality determination unit 4040 determines abnormalities in the guide lines and the transport vehicle based on the position information of the guide lines registered in the map information and the detection information of the transport vehicle including the detected position information of the guide lines detected by the transport vehicle. The control flow for determining abnormalities in the guide lines and the vehicle by the abnormality determination unit 4040 will be described in detail later.

[0034] The input / output device 5000 displays information recorded in the status information recording unit 4010 of the overall control device 4000, map information (including map update information), and the results of judgment by the abnormality judgment unit, and can add or update new operation scenarios by inputting operation scenarios managed by the operation scenario management unit 4020. Information input to the input / output device 5000 includes, for example, that the destination of a given transport vehicle is the working area A of the guided travel area 110, the operation content for entering the guided travel area 110 and arriving at the working area A, operation switching conditions, etc.

[0035] <Functions of the Transport Vehicle> The functions of the transport vehicle will be described using Figure 10. Figure 10 is a diagram showing the functional configuration of the transport vehicle according to this embodiment. The transport vehicle 10 includes a communication unit 210 that communicates with a carriage 2000 outside the transport vehicle and a communication network 6000, a recording unit 220 (including a memory unit), a detection unit 230 equipped with various sensors described below, a coupling unit 11 for coupling with the carriage, a wheel drive unit 280 that drives the wheels, an input unit 240, a display unit 250, and a control unit 260 that controls the operation of the wheel drive unit 280, etc.

[0036] The recording unit 220 has a function of recording information received from the outside by the communication unit 210, detection information detected by the detection unit 230, and information generated and output by the control unit. The recording unit 220 can store information such as the destination position of the transport vehicle, the travel route, and the travel history. The recording unit 220 can store speed information according to the distance to the destination position, calculation formula (program) information for calculating the speed information, and the like.

[0037] The detection unit 230 includes an object position detection unit 12, a guide line detection unit 16, a travel distance detection unit 233, a collision detection unit 234, a posture detection unit 235, and a charge amount detection unit 236. As described above, the object position detection unit 12 includes a laser distance sensor (such as LiDAR (Light detection and ranging)) that measures the distance and direction to an object by emitting laser light and measuring the time it takes for the light to hit the object and bounce back; a millimeter-wave radar that detects the distance to an object based on a millimeter-wave transmission signal and a received signal that is reflected by the object and returns; or a camera-type distance sensor that measures the distance to an object by photographing the object with a camera and analyzing the captured image. The control unit can estimate information about the current position and current speed of the transport vehicle based on information from the detection unit. The detection unit 230 includes a position sensor, such as a GNSS, that detects the current position of the transport vehicle, and a speed sensor that detects the speed of the transport vehicle.

[0038] As described above, the guide line detection unit 16 uses a sensor according to the type of guidance method. When the electromagnetic induction method is used, a pickup coil is used as the sensor for the guide line detection unit; when the magnetic induction method is used, a magnetic sensor is used; and when the image recognition method is used, a camera is used. The guide line detection unit detects the guide line when it is located directly above the guide line and outputs a detection signal. Furthermore, in the case of an image recognition method in which a camera reads a guide line using a two-dimensional code or barcode, position information is generated based on information from the detected code in addition to the guide line detection signal, and further, information on the relative angle between the guide line and the transport vehicle can be generated by examining image information from the code.

[0039] The travel distance detection unit 233 detects the number of rotations of the non-driven wheels 14 or the driven wheels 13, and can measure the travel distance and travel speed of the transport vehicle based on the detected information on the number of rotations and information on the diameter (or circumference) of the non-driven wheels or the driven wheels (in this case, the travel distance detection unit 233 can function as a speed sensor). As an alternative, it is also possible to apply a means for detecting the travel speed of the transport vehicle using a millimeter wave sensor that irradiates millimeter waves onto the floor surface and detects reflected waves, and estimating the travel distance by integrating the travel speed. Also, any method for measuring the travel distance or acquiring the travel speed other than the above-mentioned methods is applicable.

[0040] The collision detection unit 234 has the function of detecting when the transport vehicle collides with an object or a person. Specifically, it can detect acceleration using a gyro sensor or the like and determine that a collision has occurred when a sudden change in acceleration is detected. As an alternative, it is possible to install a physical switch along with a bumper at the front of the transport vehicle in the direction of travel and determine that a collision has occurred when the physical switch is pressed. Collision detection methods other than those described above can also be applied. When the collision detection unit 234 detects a collision, it stops the transport vehicle and records at least one of information on the collision occurrence and the collision location in a recording unit, and notifies the information to the overall control device 4000 and the control device 3000. The attitude detection unit 235 detects the direction (attitude) of the host vehicle based on a magnetic compass, information on the rotation speed of the left and right drive wheels, or wheel steering information.

[0041] The charge amount detection unit 236 detects the charge amount of the battery that is the power source for the transport vehicle. When the charge amount detected by the charge amount detection unit 236 falls below a predetermined value, the unit determines that charging is necessary, records the detection information of the decrease in charge amount in the recording unit, and notifies the information to the overall control device 4000 and the control device 3000. Furthermore, when it is detected that the charge amount is below a predetermined value, in addition to the above processing, the unit may automatically move to a charging spot and charge the vehicle. Note that the predetermined value used by the charge amount detection unit 236 to determine that charging is necessary may be a value set in advance based on at least one of the distance to the destination set for the transport vehicle and the weight of the transported object coupled to the transport vehicle.

[0042] The input unit 240 is configured with a physical switch or a touch panel mounted on the transport vehicle, and allows a user to directly input operation commands, etc. to the transport vehicle. The display unit 250 is configured with, for example, a liquid crystal panel mounted on the transport vehicle, and can display status information of the transport vehicle (various types of detection information by the detection unit 230, the type of driving mode, the operation scenario currently being executed, etc.).

[0043] The control unit 260 includes an operation determination unit 261, a mode switching unit 262, a connection control unit 263, a display control unit 264, a position estimation unit 265, and a travel control unit 266. The operation determination unit 261 determines the operation of the guided vehicle based on the operation scenario of the self-guided vehicle acquired from the operation scenario management unit 4020.

[0044] The mode switching unit 262 switches the travel mode of the transport vehicle between a guided travel mode and an autonomous travel mode based on conditions predetermined by an operation scenario or the like or commands input by the input unit 240. The connection control unit 263 controls the operation of the connection unit 11 to control connection / disconnection with a transported object such as a cart based on conditions predetermined by an operation scenario or the like or commands input by the input unit 240. The display control unit 264 controls the input IF of the input unit 240 and the display unit 250 described above.

[0045] The position estimation unit 265 can estimate the position of the vehicle at a given time, including the current position of the vehicle, within the entire travel area, based on the travel distance detected by the travel distance detection unit 233, information on the direction of the vehicle detected by the attitude detection unit 235, and map information on the entire area recorded in the recording unit 220. Alternatively, the position of the vehicle within the entire travel area can be estimated based on information on the distance and direction from the vehicle to an object measured by the object position detection unit 12 and map information on the entire area recorded in the recording unit 220. Alternatively, when the vehicle is traveling on a guide line formed by a two-dimensional code, the position of the vehicle within the entire travel area can be estimated based on the identification information of the two-dimensional code and the map information. The position estimation unit 265 can also acquire position information using a GNSS or the like provided in the transport vehicle.

[0046] The position estimation unit 265 can estimate the position of an object based on the estimated vehicle position information and the distance information from the vehicle to the object detected by the object position detection unit 12. Furthermore, based on the vehicle position information when the guide line detection unit 16 detects the guide line, it estimates the installation position of the guide line.

[0047] The travel control unit 266 controls the travel of the transport vehicle based on at least one of the determination information by the operation determination unit 261 and the mode switching unit 262. The travel control unit 266 can control the forward movement, backward movement, stopping, turning, and the moving speed and turning speed of the transport vehicle. Specifically, the travel control unit 266 individually controls the right wheel drive unit 281 and the left wheel drive unit 282 of the wheel drive unit 280. The right wheel drive unit 281 and the left wheel drive unit 282 are configured with, for example, motors, and by individually controlling the rotation speed and rotation direction of each drive wheel, it becomes possible to make the transport vehicle travel on a curve with an arbitrary trajectory radius or to rotate the transport vehicle to change direction.

[0048] The control unit 260 determines whether the distance d from the current position to the destination position is equal to or less than a predetermined value, and if it determines that the distance d is equal to or less than the predetermined value, it can control the travel speed of the transport vehicle so that the relationship between the distance d, the travel speed v, and the constant k satisfies formula [A]. That is, by applying the value of the distance d and a preset constant k to formula [A], the target travel speed v at that time is determined, and the control unit can control the drive wheels (motors in this example) to achieve this speed v. v = sqrt(2*k*d) [A]

[0049] Here, the predetermined value from the current position to the destination position for determining whether or not to apply formula [A] may be any value, such as 10 cm, 50 cm, 1 m, 10 m, 20 m, etc., and is set in advance and stored in the memory unit.

[0050] In the travel control method of this embodiment, the control unit 260 calculates the distance d to the destination position during the process of moving to the destination position (S101), as shown in Fig. 15. Note that while the distance to the destination position is equal to or greater than a predetermined distance, the transport vehicle is controlled to travel at the maximum speed (vmax) among the allowable speeds in order to improve transport efficiency.

[0051] The control unit 260 determines whether the distance d is equal to or less than a predetermined value (e.g., 10 m) (S102). If the distance d exceeds the predetermined value, the current speed (vmax) is maintained, for example. If the distance d is equal to or less than the predetermined value, the control unit 260 calculates a target speed according to the distance d based on the above formula [A] (S103).

[0052] The control unit 260 then controls the driving wheels to perform running control so that the speed is the one calculated in S103 (S104).

[0053] The control unit 260 repeats steps S101 to S104 described above until the target position is reached. This allows the speed to be increased until the target position is approached (the distance d becomes equal to or less than a predetermined value), and once the target position is approached, appropriate speed management can be used to improve stable running and stopping accuracy. In other words, it is possible to improve the stopping accuracy of the transport vehicle and improve running efficiency at the same time.

[0054] Here, Fig. 11 is a diagram showing an example of the travel speed of the transport vehicle in this embodiment based on the travel distance, Fig. 12 is a diagram showing an example of the travel speed of the transport vehicle based on time, Fig. 13 is a diagram showing an example of the travel speed of the transport vehicle as a comparative example based on the travel distance, and Fig. 14 is a diagram showing an example of the travel speed of the transport vehicle of Fig. 13 based on time.

[0055] For example, when trying to reduce the speed linearly with the distance x as shown in Fig. 13, the speed with time t becomes nonlinear as shown in Fig. 14, and there is a risk that the traveling will become unstable as the target position is approached. In particular, when transporting a heavy object, it is difficult to move stably at a low speed.

[0056] On the other hand, according to this embodiment, for example, as shown in FIG. 12, the rate of speed reduction according to time t becomes linear, and driving becomes stable even when approaching the destination position. In addition, as shown in FIG. 11, the driving distance at low speeds becomes shorter, and therefore the travel time to the destination position also becomes shorter.

[0057] The control unit 260 may execute a process to calculate the distance d based on the difference between the current position acquired from the position estimation unit 265 and the destination position acquired from the storage unit. Alternatively, the distance d may be acquired by associating information on the distance d with a two-dimensional code laid on the floor and reading the code with the transport vehicle.

[0058] The control unit 260 may control the traveling speed of the transport vehicle based on speed information acquired by a speed sensor of the transport vehicle. For example, the control unit 260 compares the target speed determined based on the distance d with the current speed of the transport vehicle, and controls the transport vehicle to accelerate if the current speed is slower than the target speed, and controls the transport vehicle to decelerate if the current speed is faster than the target speed.

[0059] The control unit 260 may be configured to execute a process of calculating the distance d at predetermined fixed intervals. The fixed interval may be, for example, 0.01 seconds, 0.02 seconds, 0.05 seconds, 0.1 seconds, 1 second, etc., and may be stored in the storage unit in advance. The control unit 260 may execute the process of calculating the distance d at shorter intervals as the distance d decreases (i.e., as the vehicle approaches the destination), rather than at fixed intervals. On the other hand, the control unit 260 may execute the process of calculating the distance d at shorter intervals as the distance d increases. Similar to the process of calculating the distance d, the control unit 260 may acquire or estimate its own position and acquire or estimate its speed at regular or irregular intervals.

[0060] The control unit 260 may calculate an appropriate torque value for the motor that drives the drive wheels based on the traveling speed v. For example, the control unit 260 may calculate a torque value corresponding to the traveling speed v based on a relational expression between the traveling speed v and the motor torque value that is stored in advance in the storage unit. By controlling the motor based on this appropriate torque value, it is possible to further improve stopping accuracy.

[0061] The control unit 260 may acquire the current position by scanning a two-dimensional code placed on the road surface. This allows current position information to be acquired quickly and easily. Note that, when the control unit detects that the transport vehicle has passed the destination position based on the current position information, it is also possible to control the travel of the transport vehicle so that it returns to the destination position.

[0062] In the above embodiment, the control mode is changed when the distance d to the destination position is greater than a predetermined value and when the distance d becomes equal to or less than the predetermined value, and the travel of the transport vehicle is controlled so that the travel speed satisfies formula [A]. However, the control mode may be further switched before the transport vehicle reaches the destination position. For example, when the distance d to the destination position becomes equal to or less than a first value (the above-mentioned predetermined value), the transport vehicle may be controlled in a first mode so that the travel speed satisfies formula [A], and then, when the distance d becomes equal to or less than a second value smaller than the first value, the control mode of the transport vehicle may be controlled in a second mode. That is, the control unit may switch the control mode of the transport vehicle in two stages depending on the distance d.

[0063] In the second mode, the travel speed may be a predetermined constant speed, or may be a speed that gradually decreases according to the distance d at a rate different from that in the first mode. When the speed is gradually decreased in the second mode, the speed may decrease linearly or quadratically with the distance to the destination (travel distance x) as the horizontal axis.

[0064] In the second mode, the attitude (angle) of the transport vehicle relative to the extension direction of the travel path (e.g., relative to the extension direction of the guide line) may be detected, and if the transport vehicle deviates from the travel path direction by a predetermined value (e.g., 1°, 5°, etc.) or more, the attitude may be controlled (turned) to bring the attitude closer to the travel path direction. By checking and correcting the angle deviation in this way, the accuracy of the stopping position can be further improved. Furthermore, such attitude detection may be repeated at predetermined intervals (a predetermined fixed period or a non-fixed fixed period). Furthermore, the control unit may detect the traveling direction (front direction of the transport vehicle) using, for example, an attitude sensor on the transport vehicle. Furthermore, the control unit may detect the extension direction of the guideline using a detection unit, or data on the position and extension direction of the guideline may be stored in advance in a map in the storage unit.

[0065] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person skilled in the art of the present disclosure can conceive of various modified or altered examples within the scope of the technical idea described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0066] The devices described herein may be implemented as stand-alone devices, or may be implemented as multiple devices (e.g., cloud servers) partially or entirely connected via a network. For example, the control unit 260 and the recording unit 220 of the transport vehicle may be implemented as different servers connected to each other via a network. In addition, in the transport system described herein, the controller 3000, the overall control device 4000, and the input / output device 5000 are configured as separate pieces of hardware connected via a network. However, some or all of the functions of the controller 3000, the overall control device 4000, and the input / output device 5000 may be implemented in the transport vehicle 10.

[0067] The series of processes performed by the device described herein may be implemented using software, hardware, or a combination of software and hardware. A computer program for implementing each function of the control unit 260 according to this embodiment may be created and installed on a PC or the like. A computer-readable recording medium storing such a computer program may also be provided. Examples of the recording medium include a magnetic disk, an optical disk, a magneto-optical disk, and a flash memory. The computer program may also be distributed, for example, via a network, without using a recording medium.

[0068] Furthermore, the processes described herein using flowchart diagrams do not necessarily have to be performed in the order shown. Some process steps may be performed in parallel. Additional process steps may be employed, and some process steps may be omitted.

[0069] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that will be apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0070] The following configurations also fall within the technical scope of the present disclosure. (Item 1) A travel control system for a guided vehicle, comprising: a control unit that determines whether a distance d from a current position to a destination position is equal to or less than a predetermined value; and, if it is determined that the distance d is equal to or less than the predetermined value, controls the travel speed of the guided vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies equation [A]: v = sqrt(2*k*d) [A]. (Item 2) The travel control system according to item 1, wherein the control unit executes a process to calculate the distance d based on a difference between the current position acquired from a position estimation unit and the destination position acquired from a storage unit. (Item 3) The travel control system according to item 1 or 2, wherein the control unit controls the travel speed of the guided vehicle based on speed information acquired by a speed sensor of the guided vehicle. (Item 4) The travel control system according to item 1 or 2, wherein the control unit executes a process to calculate the distance d at predetermined regular intervals. (Item 5) The travel control system according to Item 1 or 2, wherein the control unit calculates an appropriate torque value for a motor that drives a drive wheel based on the travel speed v. (Item 6) The travel control system according to Item 1 or 2, wherein the current position is acquired by scanning a two-dimensional code placed on a road surface. (Item 7) A travel control method for a guided vehicle, wherein the control unit determines whether a distance d from the current position to a destination position is equal to or less than a predetermined value, and when it determines that the distance d is equal to or less than the predetermined value, controls the travel speed of the guided vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies equation [A]: v = sqrt(2*k*d) [A]

[0071] 10 Transport vehicle, 11 Connection unit, 12 Object position detection unit, 13 Drive wheel, 14 Non-drive wheel, 16 Guide line detection unit, 17 Magnetic sensor, 130 Operation area, 131 Guide line, 132 Travel mode switching position, 210 Communication unit, 220 Recording unit, 230 Detection unit, 240 Input unit, 250 Display unit, 260 Control unit, 280 Wheel drive unit, 2000 Cart, 2010 Connection receiving unit, 3000 Control device, 4000 Overall control device, 5000 Input / output device, 6000 Communication network, 7000 External system

Claims

1. A travel control system for a transport vehicle, comprising a control unit that determines whether a distance d from a current position to a destination position is equal to or less than a predetermined value, and, when it is determined that the distance d is equal to or less than the predetermined value, controls the travel speed of the transport vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies the formula [A]: v = sqrt(2*k*d) [A] 2. A driving control system as described in claim 1, wherein the control unit executes a process of calculating the distance d based on the difference between the current position obtained from a position estimation unit and the destination position obtained from a memory unit.

3. A driving control system as described in claim 1 or 2, wherein the control unit controls the driving speed of the transport vehicle based on speed information acquired by a speed sensor of the transport vehicle.

4. A driving control system according to claim 1 or 2, wherein the control unit executes a process of calculating the distance d at predetermined regular intervals.

5. A driving control system according to claim 1 or 2, wherein the control unit calculates an appropriate torque value for a motor that drives a driving wheel based on the driving speed v.

6. A cruise control system according to claim 1 or 2, wherein the current position is obtained by scanning a two-dimensional code installed on the road surface.

7. A method for controlling the travel of a transport vehicle, comprising: a control unit that determines whether a distance d from a current position to a destination position is equal to or less than a predetermined value, and when it determines that the distance d is equal to or less than the predetermined value, controls the travel speed of the transport vehicle so that the relationship between the distance d, the travel speed v, and a constant k satisfies the formula [A]: v = sqrt(2*k*d) [A]

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