Method for approaching a target position in a logistics facility using an autonomous vehicle
By successively reducing speed and initiating braking at a predetermined distance, the method optimizes time and precision in autonomous vehicle target positioning, addressing the trade-off between speed and safety in logistics facilities.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- JUNGHEINRICH AG
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-11
AI Technical Summary
Existing autonomous vehicles in logistics facilities face a tension between optimizing time requirements and ensuring safety during the final approach phase, particularly in densely packed storage areas, where reducing speed early increases overall time and precision is compromised.
The method involves a successive reduction of vehicle speed from a first to a second speed during the final approach phase, with the safety field deactivated, and initiates a braking process at the second predetermined distance to ensure precise and efficient target positioning.
This approach allows for faster and more precise target positioning, minimizing the impact of safety margins on the final stopping position, enabling efficient and safe operation in densely packed environments.
Smart Images
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Abstract
Description
[0001] The present invention relates to a method for approaching a target position in a logistics facility using an autonomous vehicle, comprising sensing the surroundings of the target position by means of at least one sensing unit of the vehicle during an approach phase to the target position, wherein during the approach phase at least one safety field or safety volume is monitored by a safety device of the vehicle and the vehicle moves at a first speed, and upon falling below a predetermined first distance to the target position, the safety field or safety volume is deactivated in order to transition to a final approach phase. The invention further relates to an autonomous vehicle which is configured and capable of carrying out such a method.
[0002] In logistics facilities, and particularly in the mass storage or warehousing areas of such facilities, pallets, racks, or other load carriers are often stored in close proximity on a surface, ready to be picked up again by suitable vehicles as needed. These can be, for example, so-called block storage systems. Examples of such vehicles, which in certain configurations can also be equipped for autonomous operation, include driverless transport vehicles in the form of forklifts or under-vehicle shuttles. These shuttles, for example, can drive under special table-shaped load carriers and then pick them up by lifting the load-bearing surface on top, before transporting them. Furthermore, so-called trolleys, which have a table shape and additionally feature wheels on their legs, can also be used.
[0003] In such applications, the aim is to place the objects as close together as possible to achieve the densest possible packing within the warehouse, thereby maximizing the overall efficiency of the system relative to the required space. However, it is crucial to ensure that such autonomous vehicles are always operated safely, and collisions with objects, and especially people, must be prevented with the utmost certainty. To this end, these vehicles are equipped with safety devices that monitor their surroundings for obstacles. Furthermore, certain safety distances and tolerances must always be maintained during maneuvers, such as braking near objects.At the same time, however, it is always desirable that autonomous vehicles in logistics facilities carry out their assigned work orders as quickly and efficiently as possible in order to save time and thus costs in this respect as well.
[0004] Accordingly, a tension exists between the desired high speed of such vehicles during operation, in order to optimize the time required for work orders, including the placement of loads in a bulk storage area, and the need to comply with the aforementioned safety requirements. An example from the prior art is the autonomously driving transport system known from DE 10 2022 115 797 A1, or rather the method for operating it, in which, during the final approach phase to a target position for placing a load, the speed at which the transport system travels to a free parking area is reduced early on, which, however, significantly increases the overall time required for the placement process.
[0005] Accordingly, the object of the present invention is to further develop a generic method for approaching a target position in a logistics facility in such a way that it is optimized with regard to its time requirement and also with regard to the precision of reaching the target position.
[0006] For this purpose and to solve the problem just formulated, it is proposed according to the invention that in such a generic method, during the final approach phase, the speed of the vehicle is successively reduced from the first speed to a second speed, and when a second predetermined distance to the target position is reached during the final approach phase, a braking process with a predetermined deceleration is initiated, which is carried out until the vehicle comes to a standstill.
[0007] The inventive, successive reduction of speed during the final approach phase, in which the vehicle's safety field is deactivated, allows the vehicle to reach the desired target position with comparable precision to the transport system known from the aforementioned prior art. However, the final approach phase can be completed in a shorter time than is possible with that prior art. This enables a time-optimized approach to the target position. Furthermore, it is crucial according to the invention that the braking process begins at the second, lower speed. Therefore, the safety margins required during this braking process will have a less pronounced impact on the final stopping position than if the braking process were initiated at the first, higher speed.
[0008] It should be noted that deactivating the vehicle's safety field is necessary in such operations to reach target positions in logistics facilities where objects are tightly packed on the driving surface, particularly in bulk storage areas. Otherwise, the objects already present would be recognized as obstacles, preventing the vehicle from approaching them. Accordingly, the mapping of the target position's surroundings during the approach phase serves, among other purposes, to ensure that the intended target position is free of obstacles. This allows for verification, before transitioning to the final approach phase, that approaching the target position as desired is indeed possible.However, should it become apparent during the approach phase that the desired target position cannot be approached in the desired manner, for example because there is an object at that location, the procedure can be aborted at this point and an appropriate countermeasure initiated, such as temporarily shutting down the vehicle and informing a human operator about the undesirable presence of an obstacle at a target position.
[0009] As already indicated several times, the method according to the invention can further include setting down a load carried by the vehicle after it has come to a standstill at the end of the process, whereby this setting-down process can be carried out differently depending on the design of the respective vehicle and the type of load. To set down carried loads, a lifting device of the vehicle is usually lowered, whereby it should be noted that the lowering itself can also be started before the vehicle has come to a standstill and only completed at the target position in order to further accelerate the corresponding workflow.
[0010] Furthermore, it should be noted that in a particularly simple embodiment, the reduction of the vehicle's speed from the first speed to the second speed can occur linearly; however, any other speed profile over time can also be used, for example, a progressive or regressive reduction in speed. It is understood that the planning of the final approach phase, including the reduction in speed and the initiation of the braking process, must be carried out with regard to the corresponding timing, depending on the first and second predetermined distances, in such a way that the target position can be reached in the desired manner.The planning can be carried out in such a way that the vehicle's speed is reduced in such a way that, upon reaching the second speed, the second predetermined distance is reached and the braking process can therefore begin immediately. This planning can also take into account known time delays or reaction times that such vehicles exhibit during operation. In this way, the time required for the final acceleration phase is minimized.
[0011] Furthermore, it is possible to record the vehicle's speed and / or distance traveled during the final approach phase and, if necessary, to adjust the reduction in speed, the point at which braking is initiated, and / or the predetermined deceleration based on the recorded speed and / or distance traveled. Accordingly, in such an embodiment, the final approach phase is carried out in a controlled manner, thereby achieving further optimization of both the time required and the final precision in reaching the target position.
[0012] As already indicated several times, the target position for the vehicle in question may be in a mass storage area of the logistics facility, where objects to be stored are to be placed in the closest possible and most space-saving manner together with objects already present on the driving surface, or it may correspond to parking against a wall or an obstacle.
[0013] According to a further aspect, the present invention relates to an autonomous vehicle comprising a drive unit configured to propel the vehicle to movement in a work environment, at least one detection unit configured to detect the vehicle's surroundings, a safety device configured to establish at least one safety field in the vehicle's surroundings, and a control unit operationally coupled to the drive unit, the detection unit, and the safety device, which is configured to instruct the vehicle to carry out the method described above according to the invention.
[0014] It is understood that the drive unit will generally also include a braking device, while the control unit is configured to issue the corresponding necessary instructions for carrying out the method according to the invention to the respective components thereof, including the drive unit, the detection unit and the safety device.
[0015] Particularly in cases where the controlled approach to the target position described above is to be carried out, the vehicle according to the invention can further comprise at least one sensor unit for detecting the vehicle's speed and / or distance traveled, in particular an incremental encoder, by means of which a corresponding level of safety can be achieved in such a safety-critical application. Alternatively, however, other known sensor types could also be used, including SIN / COS encoders, odometric sensors, pulse generators, Hall sensors, gear sensors and the like.
[0016] Furthermore, it should be noted that in vehicles according to the invention, the safety device can be implemented by at least one detection unit and / or at least one detection unit can be formed by a laser scanner or a volumetric sensor. In particular, if laser scanners are used within their detection range, a safety field can be defined in the vicinity of the vehicle for the simultaneous implementation of the safety function of the safety device. During normal operation of the vehicle, no objects may be located within this safety field. This safety field can then be deactivated in the final approach phase as described above, in order to allow the vehicle to approach adjacent objects in mass storage facilities or similar environments as desired.In contrast, volumetric sensors are able to define safety volumes, which can be handled in an analogous way to safety fields with regard to their monitoring.
[0017] Further features and advantages of the present invention will become even clearer from the following description of an embodiment thereof, when viewed together with the accompanying figures. These show in detail: Fig. 1a and Fig. 1b respective schematic top views of two different embodiments of vehicles according to the invention during an approach to a target position in a logistics facility; Fig. 2 a diagram to illustrate the process of the method according to the invention in comparison to methods known from the prior art.
[0018] The Fig. 1a and Fig. Figure 1b shows, firstly, respective top views of two different embodiments of vehicles according to the invention, which are each designated by reference numerals 100 and 200. Vehicle 100 is made of Fig. 1a a sub-shuttle which carries as its load a table-shaped load carrier L1, which in a process of approaching a in Fig. The indicated target position P1 is to be positioned between identically constructed load carriers L2 already standing on the road surface in a mass storage area of a logistics facility.
[0019] Similarly, the Fig. 1b a driverless transport vehicle 200 as a vehicle according to the invention, which transports a load L3 and, in the example shown here, is intended to place it as close as possible to a wall W, which in Fig. 1b corresponds to the target position P2. For this purpose, each vehicle includes a lifting device that enables the lifting and lowering of a corresponding load. Both vehicles 100 and 200 are also similarly constructed with regard to the components necessary for their autonomous operation and each includes a drive unit (not shown) with at least one drive motor, a steering system, and at least one brake, by means of which the vehicle can be propelled to movement within the work environment. Depending on the vehicle type, the steering system can, for example, be implemented in such a way that two or more rigid drive wheels are operated at different speeds.
[0020] Furthermore, vehicles 100 and 200 each comprise at least one detection unit, for example, a plurality of laser scanners 102, 202 or volumetric sensors, which are configured to detect the vehicle's surroundings and which simultaneously constitute a safety device, since with their help a safety field or safety volume can be defined in part of their detection range in the vicinity of the respective vehicle 100 or 200. Vehicles 100 and 200 also each comprise control units 104 and 204, respectively, which are operationally coupled to the aforementioned and other components not described here for the operation of vehicles 100 and 200 and can control them appropriately.
[0021] To now put the two in the Fig. 1a and Fig. To achieve the target positions indicated in 1b as quickly and with the highest possible precision, a method according to the present invention is carried out, which is described below using the following examples: Fig. 2 will be described in comparison with methods known from the prior art. Here, the x-axis corresponds to Fig. 2 the distance travelled, for example in relation to the corresponding axis Fig. 1a.
[0022] In this process, the corresponding vehicle (100 or 200) initially travels at a high speed (v_0) during an approach phase to the target position with the corresponding x-coordinate (x_max). Subsequently, if a predetermined initial distance is breached, a final approach phase begins, during which the speed is gradually reduced from the initial speed (v_0) to a second, lower speed (v_1), as shown in... Fig. 2 is represented by a solid line. At the same time, at least one of the previously mentioned safety fields of vehicle 100 or 200 is deactivated to allow closer approach to objects in the vicinity of the vehicle. In the example shown, the reduction in speed from v_0 to v_1 occurs linearly; however, other reduction profiles are conceivable, including a controlled reduction based on sensor data regarding the vehicle's speed and / or distance traveled in this section of the procedure.
[0023] Subsequently, upon reaching a second predetermined distance x_1', which is determined by the location x_1 of reaching the second velocity v_1 and a subsequent system reaction time, a braking process is initiated with a predetermined deceleration. This process continues until the vehicle comes to a standstill at the corresponding position x_1_min, which is very close to the optimal target position x_max. It is important to note that such braking processes must always be performed with a deceleration greater than the theoretically best deceleration required to reach the desired target position. This ensures that even in the case of the worst practically occurring deceleration, a collision with objects potentially located behind the target position is prevented.
[0024] Furthermore, in Fig.Figure 2 shows two alternative approaches, both known from the prior art, in dashed and dotted lines respectively. On the one hand, an approach can be made at a significantly earlier point in time at the reduced second speed v_1, with which the same target position x_1_min is reached simultaneously with the initiation of the braking process. However, since a significantly longer distance is traveled at the lower speed v_1, this process takes considerably longer and is therefore less efficient than the method according to the present invention.
[0025] However, if, on the other hand, the higher speed v_0 is maintained until a later time or a location x_0' closer to the target position, which again includes a reaction time between x_0 and x_0', and the braking process is then started immediately, the target position x_max cannot be reached with the same precision due to the necessary safety margin described above for such a braking process, and the vehicle will stop at position x_0_min. Due to this greater distance from the intended target position, for example, in a case where an object is to be positioned at this location in a mass storage area, such a dense packing of objects cannot be achieved as in the present method according to the invention, so that this method achieves the best possible result with regard to both its duration and the packing density of the objects to be placed. QUOTES INCLUDED IN THE DESCRIPTION
[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature
[0000] DE 10 2022 115 797 A1
[0004]
Claims
[1] Method for approaching a target position (P1, P2) in a logistics facility by an autonomous vehicle (100, 200), comprising: - Detection of the environment of the target position (P1, P2) by means of at least one detection unit (102, 202) of the vehicle (100, 200) during an approach phase to the target position (P1, P2), wherein during the approach phase at least one safety field or safety volume is monitored by a safety device (102, 202) of the vehicle (100, 200) and the vehicle (100, 200) moves at a first velocity (v_0); and - if a predetermined initial distance to the target position (P1, P2) is not reached, at least one safety field or safety volume is deactivated in order to enter a final approach phase; characterized by , that the procedure further includes: - during the final approach phase, successive reduction of the vehicle's speed (100, 200) from the first speed (v_0) to a second speed (v_1); and - upon reaching a second predetermined distance (x_1') to the target position (P1, P2) during the final approach phase, initiating a braking process with a predetermined deceleration, which is carried out until the vehicle comes to a standstill (100, 200). [2] Method according to claim 1, further comprising setting down a load (L1, L3) carried by the vehicle (100, 200) after the vehicle has come to a standstill. [3] Method according to one of the preceding claims, wherein the reduction of the speed from the first speed (v_0) to the second speed (v_1) is carried out in a linear manner. [4] Method according to one of the preceding claims, wherein the reduction of the speed of the vehicle (100, 200) is carried out in such a way that upon reaching the second speed (v_1) the second predetermined distance (x_1') is reached and the braking process is started immediately. [5] Method according to one of the preceding claims, wherein during the final approach phase the speed and / or the distance traveled by the vehicle (100, 200) is recorded. [6] Method according to the preceding claim, further comprising adjusting the reduction of speed, a time of initiation of the braking process and / or the predetermined deceleration based on the detected speed and / or distance traveled. [7] Method according to one of the preceding claims, wherein the target position is located in a mass storage area of the logistics facility or corresponds to parking against a wall or obstacle. [8] Autonomous vehicle (100, 200), comprising: - a drive unit designed to propel the vehicle (100, 200) to movement in a work environment; - at least one detection unit (102, 202) which is designed to detect the vehicle's surroundings (100, 200); - a safety device (102, 202) which is designed to establish at least one safety field in the vicinity of the vehicle (100, 200); and - a control unit (104, 204) operationally coupled with the drive unit, the detection unit (102, 202) and the safety device (102, 202), which is configured to instruct the vehicle (100, 200) to carry out a method according to one of the preceding claims. [9] Vehicle (100, 200) according to claim 8, further comprising a sensor unit for detecting a speed and / or a distance traveled by the vehicle (100, 200), in particular an incremental encoder. [10] Vehicle (100, 200) according to claim 8 or 9, wherein the safety device (102, 202) is implemented by the at least one detection unit (102, 202) and / or at least one detection unit (102, 202) is formed by a laser scanner or a volumetric sensor.