METHOD FOR PLANNING A ROUTE FOR A DRIVERLESS TRANSPORT VEHICLE

Description

[0001] The present invention relates to a method for planning a route for a driverless transport vehicle which can be operated in two different operating modes, as well as a method and a system for operating such a driverless transport vehicle.

[0002] Automated guided vehicles (AGVs) are autonomously or semi-autonomously operated vehicles that perform transport functions in logistics facilities and are often referred to as AGVs (automated guided vehicles). For their locomotion, these vehicles are equipped with appropriate drives and control devices that enable them to travel along specific routes or paths, for example, to travel between two stations where the respective transport vehicle can be loaded or unloaded. Furthermore, such automated guided vehicles are usually equipped with sensors that fulfill safety functions on the one hand and contribute to the orientation of the vehicles on the other, such as laser scanners and / or time-of-flight (TOF) cameras.

[0003] For the planning of the mentioned paths, two different approaches have essentially been pursued in the prior art: on the one hand, the specification of precisely planned routes within the said logistics facility, which must be strictly followed by the driverless transport vehicles, while on the other hand, the strategy is also known to only specify areas, for example in connection with nodes and edges on planning graphs, within which the transport vehicles can individually and dynamically plan a route, whereby, for example, a deviation from the corresponding nodes and / or edges is permissible within a certain tolerance for the industrial trucks, whereby the areas are defined in practice.

[0004] In many cases, the second variant is preferable from a practical perspective, as the vehicles typically orient themselves based on their surroundings and continuously attempt to find an optimal or at least suitable path within a defined movement area. This can improve the flexibility and availability, and thus the efficiency, of the logistics facility compared to fixed, planned routes. For example, the current traffic volume and the individual maneuverability of the vehicle can be taken into account to generate an efficient and time-saving path. However, situations can also arise in such scenarios in which such a strategy has its disadvantages.

[0005] This may be the case, for example, if a route traversed by an automated guided vehicle is so narrow that a deviation within even the smallest tolerance could trigger the vehicle's safety systems, for example because a wall or other stationary object would enter the protective field of a safety scanner on the transport vehicle, which would lead to a malfunction of the vehicle.

[0006] An example of an autonomous vehicle, such as a lawnmower or an agricultural vehicle, that exhibits different behavior in different areas of an environment it is driving over is known from WO 2020 / 156843 A1. A driverless transport vehicle is also known from patent application US 2015 / 285644 A1.

[0007] It is therefore the object of the present invention to provide an improved method for planning a route for a driverless transport vehicle, with which the problems mentioned in the methods known from the prior art are eliminated and an efficient yet safe movement of such a transport vehicle is possible at all times.

[0008] For this purpose, it is assumed that the corresponding driverless transport vehicle can be operated in two different operating modes, namely a first operating mode in which the transport vehicle follows a fixed, predetermined trajectory, and a second operating mode in which the transport vehicle follows a dynamically generated path that must lie within a predetermined range of motion. The method comprises dividing an environment traversable by the transport vehicle into first areas in which the transport vehicle is to be operated in the first operating mode, and second areas in which the transport vehicle is to be operated in the second operating mode, defining a corresponding trajectory to be traversed by the transport vehicle for each of the first areas, and defining a corresponding predetermined range of motion for each of the second areas.

[0009] In this way, the space available for the movement of the transport vehicle can be subdivided in a suitable manner to define areas in which fixed, predetermined trajectories must be followed, for example, in the sections already indicated above, in which only a very small space is available for the movement of the transport vehicle, or, for example, in the area of ​​an entrance and / or exit from stations to be reached, while in other areas, where such restrictions do not apply, movement within the predetermined movement area is permitted according to the second operating mode. In this way, the advantages of the two operating modes mentioned above can be combined in a way that enables efficient and safe operation of a corresponding driverless transport vehicle at all times.

[0010] The term "dynamically generated path" is to be understood as meaning that, based on a corresponding predefined movement area, such a path is created by a control unit during the transport vehicle's runtime based on predefined criteria, for example, by executing optimization algorithms related to a predicted travel time or a distance to be covered. Furthermore, it is understood that the terms "first and second areas" are not to be understood as meaning that a plurality of such areas must actually be present in an environment; rather, according to the invention, only a first and / or a second area can be provided in the environment to be subdivided.

[0011] For each transition between a first area and a second area, the method can further comprise defining a transition point or transition area such that a continuous transition between the first operating mode and the second operating mode is possible. This particularly relates to the driverless transport vehicle being able to transition from the first operating mode to the second operating mode and vice versa with minimal loss of time, without stopping or having to cover additional distances. For this purpose, it can be required, for example, not only that the vehicle approaches a fixed transition point at which the change from one operating mode to the other is made, but also that a predetermined spatial orientation orThe vehicle's direction of travel is required in order to be able to immediately transition to a fixed trajectory beginning at this transition point in the required orientation. Furthermore, it may also be required that the vehicle arrive at the transition point at a predetermined speed, for example, at a predetermined fixed speed value or at a speed below a predetermined maximum speed.

[0012] As already indicated above, the trajectories of the first areas or the definition of the specified movement areas of the second areas can be carried out using nodes and edges, using conventional graph methods. In particular, the specified movement areas in the second areas can be defined using tolerance ranges around edges and nodes, allowing certain maximum distances from the edges and nodes. Of course, any other parameterizations of a possible movement area would also be conceivable, for example, simply defining traversable areas and start and end points of the path to be traveled.

[0013] Furthermore, the present invention relates to a method for operating a driverless transport vehicle, which on the one hand comprises carrying out the method just described for planning a route at a central server, wherein data are generated which represent the environment which can be driven through by the transport vehicle, as well as transmitting the data to the driverless transport vehicle and operating the driverless transport vehicle in such a way that it follows the corresponding fixed trajectory in the first areas and that it dynamically generates a path in the second areas which it then follows.

[0014] The method for operating the driverless transport vehicle can further comprise detecting the surroundings of the transport vehicle using at least one sensor unit during operation of the transport vehicle, wherein the information thus recorded is taken into account in the dynamic path generation. In this way, the driverless transport vehicle is enabled to react in real time to changes in its operating environment and to dynamically generate an efficient path, which can be optimized, for example, with regard to minimizing the expected travel time or distance to be covered.

[0015] Although in the first areas with their predetermined trajectories, such detection of the surroundings of the transport vehicle cannot be used to adapt the path to be traveled by the transport vehicle, the data from the at least one sensor unit can nevertheless also be used in these first areas for other purposes, for example, error detection or the detection of obstacles that would make travel on the predetermined, fixed trajectory impossible and thus require intervention by a human operator. Furthermore, in this context, the functionality can also be implemented, for example, that upon such detection of an obstacle in a first area, the speed is automatically adjusted, possibly up to a complete stop of the vehicle, without departing from the predetermined trajectory.

[0016] According to a further aspect, the present invention relates to a system for operating a driverless transport vehicle according to such a method, comprising a central server which is configured to enable implementation of the method according to the invention for planning a route, and the corresponding driverless transport vehicle which is configured to receive the data generated by the central server and to be operated in both the first and the second operating mode.

[0017] The transmission of data from the central server to the driverless transport vehicle can take place, for example, via a wireless communication connection, which would enable the data to be adapted even during ongoing operation of the transport vehicle, or the corresponding data can be uploaded locally to the transport vehicle using a data storage device when the transport vehicle is put into operation or overhauled.

[0018] As already indicated, at least one sensor unit for detecting its surroundings can be assigned to the transport vehicle, wherein the data recorded by this at least one sensor unit can be used in the manner described above for the dynamic generation of a path to be covered in the second operating mode and overall for the detection of obstacles and disturbances.

[0019] Further features and advantages of the present invention will become more apparent from the following description of an embodiment thereof, when considered together with the accompanying figures. These show in detail: Figure 1 shows a schematic representation of a system according to the invention for operating a driverless transport vehicle; Figure 2 shows a flow chart illustrating a method for operating the driverless transport vehicle from Figure 1 and Figure 3 is a schematic representation of a transport vehicle from the Figure 1 drivable environment.

[0020] In Figure 1First of all, a system for operating an automated guided vehicle is shown purely schematically and is generally designated by the reference numeral 10. The system comprises a central server 12 and the actual automated guided vehicle 14 with its own control unit 14a and at least one sensor unit 14b. The sensor unit 14b can be configured to monitor the surroundings of the transport vehicle 14 to ensure compliance with safety requirements and / or to orient the transport vehicle 14. Furthermore, the server 12 and the transport vehicle 14 are in data communication with one another, for example, via a wireless communication channel, which is indicated by the reference numeral 16.

[0021] Furthermore, in addition to a memory 18 and a processor unit 20, the central server 12 is also assigned a user interface 22, which can be formed, for example, from a touchscreen or a combination of a screen with a keyboard and / or other input devices. By means of the user interface 22, a human user of the central server is enabled, within the scope of the Figure 2 to carry out a route planning for the driverless transport vehicle 14 using the method shown and described below, wherein a possible representation for visualising this route planning on the user interface 22 in Figure 3 and is also described below.

[0022] The data generated in this context with regard to the route planning carried out can then be transmitted via the communication channel 16 to the industrial truck 14, which can then travel routes in the corresponding environment according to the two operating modes under the control of the control unit 14a.

[0023] Referring to the flowchart from Figure 2 The method according to the invention for operating the driverless transport vehicle will now be explained, which initially comprises a method for planning a route for the driverless transport vehicle 14. For this purpose, in step S1, a drivable environment, for example a logistics facility, is first specified or created, which represents the entire space for which routes are possible for the transport vehicle 14, and which may, for example, contain accessible stations or other waypoints.

[0024] Subsequently, in step S2, the drivable environment is subdivided into first areas and second areas, wherein the transport vehicle has to follow fixed trajectories in the first areas and in the second areas is to follow a dynamically generated path, which has to lie within a predetermined range of motion and thus offers increased flexibility with regard to optimizing travel time, avoiding obstacles and the like.

[0025] Accordingly, in step S3, which can occur subsequently or simultaneously with step S2, corresponding fixed trajectories and predefined movement areas can be defined. This planning can be carried out, for example, using graphs with the aid of edges and nodes. Furthermore, in step S3, transition points or transition areas can be defined in which respective transitions between the first and second areas, and thus between the first and second operating modes of the driverless transport vehicle 14, are to take place.

[0026] Based on the division of the drivable environment into first and second areas and the definition of the trajectories to be traveled or predetermined movement areas, the central server 12 now generates data that can be used by the industrial truck 14 in step S4, which data are also transmitted in step S4 to the transport vehicle 14, for example by means of wireless communication or via a corresponding data carrier, and are stored and retained by the latter for further use by the control unit 14a.

[0027] Subsequently, in step S5, the driverless transport vehicle 14 is equipped with all the data necessary for regular operation and can be operated in the usual way to perform transport tasks within the drivable environment. For this purpose, it travels paths in corresponding first and second areas of the defined environment in its first and second operating modes. In particular, in the second operating mode, such paths are generated dynamically during the runtime of the transport vehicle 14 with the aid of the control unit 14a based on the available data, with information about the environment of the transport vehicle 14 acquired by at least the sensor unit 14b also being used.

[0028] Finally, with reference to Figure 3The schematic representation of an operating environment U of the industrial truck 14 shown therein explains how path planning can be visualized in a concrete example. Here, the environment U contains two walls W1 and W2, which represent insurmountable obstacles for the automated guided vehicle 14 and thus define non-driveable areas. On the other hand, a drivable surface is designated by reference symbol G in Figure 3.

[0029] In the Figure 3 In the example illustrated, the task is to guide the industrial truck 14 from a starting point S to a destination point Z, whereby this destination point Z lies between the two walls W1 and W2 and the corridor that can be driven there is so narrow that dynamic path planning would lead to problems at this point.

[0030] Accordingly, in the method according to the invention, the drivable subsurface G of the environment U is subdivided into a first area B1 and a second area B2 Figure 3 The movement is carried out in the hatched area B2, wherein in the first area B1 the transport vehicle 14 has to follow the fixed trajectory P1, while in the second area B2 the entire hatched area is initially permitted for movement of the transport vehicle 14, so that in the illustrated example the second area B2 is identical to a predetermined movement area. In other examples, however, a predetermined movement area could also only be present in a part of a second area, for example if nodes and edges of a graph are defined in this area and the corresponding movement area has to lie within a predetermined tolerance thereof.

[0031] Furthermore, a transition point T has been defined, at which the actual transition between the second operating mode and the first operating mode of the transport vehicle 14 is to take place when traveling the path from the starting point S to the destination point Z. Accordingly, when the journey begins at the starting point S, the transport vehicle 14 first dynamically generates a path to the transition point T based on predetermined criteria and algorithms, which path is designated P2 in the example shown here and for which the entire area B2 is suitable in principle.

[0032] At the transition point T, the transport vehicle 14 now switches to the fixed trajectory P1 and then follows it as precisely as possible and without deviation to the destination point Z in order to be able to move smoothly in the narrow corridor between the two walls W1 and W2 in a safe manner and with sufficient distances, while no warnings or disturbances are issued by safety systems, such as the sensor unit 14b.

[0033] In the case of an opposite movement from point Z to point S, an analogous movement can accordingly take place in the reverse manner, i.e. first following the trajectory P1 from point Z to the transition point T and then dynamically generating a path P2 in the second area B2 and following this path.

Claims

1. Method for planning a route for a driverless transport vehicle (14) which can be operated in two different operating modes: - a first operating mode in which the transport vehicle (14) follows a firmly predetermined trajectory (P1), and - a second operating mode in which the transport vehicle (14) follows a dynamically generated path (P2) which should lie within a predetermined range of movement (B2); the method comprising: - dividing surroundings (U) which can be travelled by the transport vehicle (14) into first regions (B1), in which the transport vehicle (14) should be operated in the first operating mode, and second regions (B2), in which the transport vehicle should be operated in the second operating mode (S2); - for each of the first regions (B1), defining a corresponding trajectory (P1) to be travelled by the transport vehicle (14) (S3); and - for each of the second regions (B2), defining a corresponding predetermined range of movement (B2) (S3).

2. Method according to Claim 1, further comprising, for each transition between a first region (B1) and a second region (B2), defining a transition point (T) or transition region in such a manner that a continuous transition between the first operating mode and the second operating mode is possible (S3).

3. Method according to any one of the preceding claims, wherein the definition of the trajectories (P1) of the first regions (B1) and / or the definition of the predetermined ranges of movement (B2) of the second regions (B2) is performed using nodes and edges.

4. Method according to Claim 3, wherein the predetermined ranges of movement (B2) are defined on the basis of tolerance ranges around edges and nodes.

5. Method for operating a driverless transport vehicle (14), comprising: - performing the method for planning a route according to any one of the preceding claims in a central server (12), wherein data are generated which represent the surroundings (U) through which the transport vehicle (14) can travel; - transmitting the data to the driverless transport vehicle (14) (S4); and - operating the driverless transport vehicle (14) in such a manner that it, in the first regions (B1), follows the corresponding firmly predetermined trajectory (P1) and that it, in the second regions (B2), dynamically generates a path (P2) which it subsequently follows (S5).

6. Method according to Claim 5, further comprising recording the surroundings (U) of the transport vehicle (14) by means of at least one sensor unit (14b) during the operation of the transport vehicle (14), wherein the information recorded in such a manner is taken into account in the dynamic path generation.

7. System (10) for operating a driverless transport vehicle (14) according to a method according to any one of Claims 5 and 6, comprising: - a central server (12) which is configured to enable the method for planning a route according to any one of Claims 1 to 4 to be performed; - the driverless transport vehicle (14) which is configured to receive the data generated by the central server (12) and to be operated in both the first and the second operating mode.

8. System (10) according to Claim 7, wherein a wireless communication connection (16) for a transmission of data from the central server (12) to the driverless transport vehicle (14) is provided.

9. System (10) according to Claim 7 or 8, wherein an adjustment of the data is enabled during ongoing operation of the transport vehicle (14).

10. System (10) according to any one of Claims 7 to 9, wherein at least one sensor unit (14b) for recording the surroundings (U) of the transport vehicle (14) is assigned to the transport vehicle (14).