Method for operating an autonomously guided industrial truck

Abstract

The invention relates to a method for operating an autonomously guided industrial truck (1; 1a, 1b, 1c, 1d) that transports cargo, in which a safety area (5, 6) is defined and at least one sensor (2, 2a) is used to monitor the safety area (5, 6) in order to detect any obstacles. Improved navigation can be achieved by using sensors (2) to determine the dimensions of the cargo and taking the determined dimensions as a basis for defining the safety area (5, 6).

Description

[0001] Method for operating an autonomously guided industrial truck

[0002] The present invention relates to a method for operating an autonomously guided industrial truck that transports loads, in which a safety field is defined and monitored via sensors to detect any obstacles. This also enables efficient navigation and route planning of the vehicle.

[0003] Autonomously navigating vehicles always require sensors to avoid collisions with obstacles, i.e., objects, other vehicles, or people. The safety field is the outline of the vehicle projected in the direction of travel, i.e., the area that must be free of obstacles to ensure collision-free travel.

[0004] On the one hand, the safety field is continuously monitored during the journey itself to detect suddenly appearing obstacles and avoid a collision by braking or swerving. On the other hand, it is also taken into account when planning a route to avoid paths that are too narrow for safe passage due to fixed obstacles. In railway engineering, such a safety field is also commonly referred to as the clearance gauge.

[0005] For industrial trucks used in warehouses, such as forklifts, the required safety zone is usually defined by the load or its geometric shape / extension, as this extends beyond the outline of the vehicle itself and thus represents the limiting factor in route planning. Typically, the load is stored on a load carrier, such as a pallet. In a warehouse, load carriers of different dimensions are generally used to store and transport loads of different sizes in an economical manner.

[0006] Conventional autonomously navigating industrial trucks cannot determine the size and shape of the load being transported at any given time, so the largest possible load carrier with the maximum permissible load must always be used as a benchmark when determining the safety field. This means, however, that unnecessarily long routes may be used during route planning to avoid supposed bottlenecks that would be perfectly passable when transporting a smaller load, and that unnecessary braking and evasive maneuvers may occur during the journey due to a lack of knowledge of the actually required safety field.

[0007] There are industrial trucks that can switch between two safety fields of different sizes, but this switching is done via external commands generated based on data about the load. These systems are prone to failure, so incorrect user input and / or errors in warehouse accounting can lead to collisions and serious accidents.

[0008] Load carriers are used in logistics in a wide variety of sizes, shapes, and configurations. Typical load carriers include pallets, long pallets, reusable containers, containers, boxes, wire mesh crates, big bag systems, IBCs, and GLT. Generally speaking, industrial trucks, AGVs (driverless transport systems) or AMRs (autonomous mobile robots) for transporting load carriers can be equipped with two lifting forks or, alternatively, with a single fork, or alternatively, with a lifting table or a modular lifting platform. The lifting forks and individual forks can be designed in a wide variety of shapes, widths, and lengths. Industrial trucks, AGVs, and AMRs are also used without any lifting forks.In this case, the lifting of a load carrier is carried out, for example, by lifting a support plate, a lifting table or by lifting the entire vehicle, which drives directly under the load carrier.

[0009] The object of the invention is to avoid these disadvantages and safety risks and to provide a method that enables safe operation while optimally utilizing the available space for navigation. A further object is to provide an industrial truck that can be operated flexibly, safely, and with the best possible use of the available space.

[0010] According to the invention, sensors are used to determine the dimensions of the load, and the safety field is determined based on these dimensions. This allows for optimal design of both the autonomous driving itself, i.e., the avoidance of obstacles, and the route planning.

[0011] A key aspect of the present invention is that the industrial truck can independently determine its own space requirements and perform its own navigation based on them. In the simplest case, there are two different sizes of load carriers, and the method according to the invention determines whether a small or a large load carrier and its load are currently being transported.

[0012] A particularly simple method can be implemented by having the additional sensors determine the dimensions of the load based on the dimensions of a load carrier on which the load is stored. The idea behind this is that it is generally stipulated that the load may not protrude beyond the load carrier in plan view. If compliance with this rule can be assumed, then it is sufficient to determine the size of the load carrier to at least know the maximum lateral dimensions of the load. In conjunction with a known maximum height, this makes it easy to define the safety field.

[0013] A particularly advantageous embodiment of the invention provides that the following steps are carried out one after the other before the cargo is transported:

[0014] ■ Detecting the width of the load carrier;

[0015] ■ Inserting a lifting fork into a load carrier on which the load is stored;

[0016] ■ Lifting the load carrier;

[0017] ■ Detecting the free space beneath the load carrier.

[0018] The first two steps can be carried out in the order given above, or in the reverse order, i.e. the width of the load carrier is only recorded when the lifting fork is inserted into the load carrier.

[0019] In any case, the detection and determination of the safety field preferably takes place immediately after the load is picked up. At the same time, after the load carrier has been lifted, a check is performed to determine whether the detection was correct. For example, an object placed directly next to the load carrier could have been mistakenly interpreted as part of the load carrier during the first detection. Since this object, unlike the lifted load carrier itself, is still detected during the second detection even after the load carrier has already been lifted, the incorrect detection can be identified and corrected, for example, by repeating the measurement.

[0020] It is advantageous to define a cross-section perpendicular to the direction of travel as the safety field, the width of which corresponds to the width of the load detected by the other sensors plus specified safety distances. This makes it easy to determine the minimum requirement for collision-free travel.

[0021] In principle, it is possible for the sensors used to monitor the safety field to be different from the sensors used to determine the width of the load. However, a particularly efficient variant of the method according to the invention provides for the determination of the width of the load using the same sensors used to monitor the safety field. This means that the sensors for the different tasks are identical.

[0022] Preferably, several sensors are provided to monitor the safety field. These are mounted, for example, in the front corners of the industrial truck in the direction of travel. The typical direction of travel of the industrial truck is the one in which the load is picked up at the rear in the direction of travel, i.e., the opposite of a conventional forklift.

[0023] The invention also encompasses an industrial truck for the autonomous transport of loads, with at least one sensor for monitoring a safety field. The industrial truck is designed, for example, like a forklift.

[0024] According to the invention, the industrial truck is characterized in that the sensor is designed to determine the dimensions of the load in order to define the safety field as a function thereof.

[0025] The sensor can be designed as a LIDAR sensor.

[0026] LIDAR (Light Detection and Ranging) allows for precise optical measurement / scanning of the environment using rotating lasers. This is a form of three-dimensional or two-dimensional laser scanning. Instead of radio waves like radar, laser beams are used. The result is a point cloud with highly accurate X, Y, and Z coordinates of the respective measurement points.

[0027] Preferably, the sensor for monitoring a safety field is designed such that it scans essentially horizontal scanning planes during operation.

[0028] A wide variety of sensors and detection systems can be used for this application (LIDAR, ultrasound, radar, 3D cameras, TOF time-of-flight mono / stereo cameras, etc.), which can provide data for obstacle / object detection. In imaging systems, a software module can subsequently evaluate this data and detect corresponding obstacles / objects, as well as record their location and position. The analysis of the imaging / sensor data and the processing of the detections can be performed using software-based methods such as conventional algorithms or AI methods (e.g., neural networks).

[0029] The present invention will now be explained in more detail with reference to the exemplary embodiments illustrated in the figures. They show, in schematic form:

[0030] Fig. 1 shows schematically an industrial truck according to the invention of a first embodiment of the invention without load carriers;

[0031] Fig. 2 the industrial truck of Fig. 1 with a small load carrier;

[0032] Fig. 3 the industrial truck of Fig. 1 with a large load carrier;

[0033] Fig. 4 shows schematically an industrial truck according to the invention of a second embodiment of the invention without load carriers;

[0034] Fig. 5 the industrial truck of Fig. 4 with a small load carrier;

[0035] Fig. 6 the industrial truck of Fig. 5 with a large load carrier;

[0036] Fig. 7 the industrial truck of Fig. 2 with the safety field shown;

[0037] Fig. 8 the industrial truck of Fig. 3 with the safety field shown;

[0038] Fig. 9 exemplary embodiments of an industrial truck according to the invention in side view.

[0039] 1 to 3 show an industrial truck 1 according to the invention in a first embodiment of the invention. Figs. 2 and 3 show the detection of the width bi, bz of a load carrier 4. Sensors 2 are arranged at the two front corners of the industrial truck 1, which is designed as a forklift truck and has a chassis 8 and lifting forks 3, which serve to pick up loads. The front of this industrial truck 1 refers to the side opposite the lifting forks 3, since in normal operation the direction of travel is indicated by the arrow 7. This means that the two lifting forks 3 are at the rear, although it should be noted that such industrial trucks 1 are typically omnidirectionally movable for shunting purposes.

[0040] In the case of a small load carrier (Fig. 2), the width b of the industrial truck 1 may exceed the width bi of the load carrier 4, so that the sensors 2 do not detect the load carrier 4. The information obtained is that the width bi of the load carrier 4 and thus of the load is smaller than the width b of the industrial truck 1, which thus represents the limiting factor when considering any obstacles.

[0041] In the case of a large load carrier 4 (Fig. 3), in the simplest case, it can only be detected that a large load carrier 4 is present, so that the known dimensions of such a load carrier 4 are then taken as a reference. Preferably, however, the width bz is measured precisely so that the required passage widths can be precisely determined.

[0042] Figs. 2 and 3 also show the scanning areas 9 of the sensors 2 for detecting the dimensions of the load carrier 4. It can be seen from Fig. 2 that for a small load carrier 4 whose width bi is smaller than or at most equal to the width b of the industrial truck 1, no direct detection takes place.

[0043] Figs. 4 to 6 largely correspond to Figs. 1 to 3, with the difference that the sensors 2 are arranged at the rear corners of the industrial truck 1 and that further sensors 2a are provided which are oriented towards the front.

[0044] Figs. 7 and 8 show the industrial trucks 1 together with the safety fields monitored by the sensors 2, whose widths bs and b4 correspond to the widths bi and bz of the load carriers 4 plus an appropriate safety distance s on each side.

[0045] Fig. 9 shows, by way of example, possible embodiments of industrial trucks 1 according to the invention in a side view. Starting from the left, a vehicle 1a with a single short lifting fork / lifting platform is shown. This is followed in second place from the left by a vehicle 1b with conventional lifting forks 3 for classic pallets, in third place by a lifting vehicle 1c with raised lifting forks 3 and a scissor-type lifting mechanism underneath, and in fourth and last place by a vehicle 1d with a higher lifting capacity and lifting forks, designed as a free-lift vehicle. Free lift is the design that does not require a lifting mechanism below the lifting forks; in this way, the lifting forks can be inserted even into load carriers that are closed on all sides.

Claims

PATENT CLAIMS 1. Method for operating an autonomously guided industrial truck (1; 1a, 1b, 1c, 1d) which transports loads, in which a safety field (5, 6) is defined and the safety field (5, 6) is monitored via at least one sensor (2, 2a) in order to detect any obstacles, characterized in that sensors (2) are used to determine the dimensions of the load and that the safety field (5, 6) is determined as a function of the determined dimensions.

2. Method according to claim 1, characterized in that the sensors (2) determine the dimensions of the load on the basis of the dimensions of a load carrier (4) on which the load is stored.

3. Method according to one of claims 1 or 2, characterized in that before the transport of the cargo the following steps are carried out in succession: ■ Detecting the width of the load carrier (4); ■ Inserting a lifting fork (3) into a load carrier (4) on which the load is stored; ■ Lifting the load carrier (4); ■ Detecting the free space below the load carrier (4).

4. Method according to one of claims 1 to 3, characterized in that a cross-section perpendicular to the direction of travel (7) is defined as the safety field (5, 6), the width (bs, b4) of which corresponds to the width (bi, bz) of the load carrier (4) or of the load, detected by the sensors (2), plus defined safety distances (s).

5. Method according to one of claims 1 to 4, characterized in that the determination of the width (bi, bz) of the load is carried out with the same sensors (2) as the monitoring of the safety field (5, 6).

6. Method according to one of claims 1 to 5, characterized in that several sensors (2, 2a) are provided for monitoring the safety field (5, 6).

7. Industrial truck (1; 1a, 1b, 1c, 1d) for the autonomous transport of loads, with at least one sensor (2, 2a) for monitoring a safety field (5, 6), characterized in that the sensor (2) is designed to is formed to determine the dimensions of the load in order to define the safety field (5, 6) depending thereon.

8. Industrial truck (1; 1a, 1b, 1c, 1d) according to claim 7, characterized in that the sensor (2, 2a) is designed as a LIDAR sensor.

9. Industrial truck (1; 1a, 1b, 1c, 1d) according to one of claims 7 or 8, characterized in that the sensor (2, 2a) scans substantially horizontal scanning planes for monitoring a safety field (5, 6).

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