AUTONOMOUS FORKLIFT FOR LIFTING AND TRANSPORTING A LOAD AND ASSOCIATED METHOD

Description

technical field

[0001] The present invention relates to the field of autonomous vehicles for the automated transport of loads, such as autonomous forklifts. Prior art

[0002] Autonomous vehicles for transporting loads are increasingly being used to increase productivity and improve logistics management in factories or warehouses.

[0003] Automated forklift trucks are an example of such vehicles and allow, for example, loading, transporting and positioning a load at height without human intervention.

[0004] However, in environments such as factories or warehouses, human intervention remains necessary to complement automated operations, for example, to monitor the smooth running of these operations or to perform tasks that cannot be carried out by machines alone. These environments are therefore shared between humans and autonomous machines.

[0005] The safety of people is fundamental in such working environments and therefore requires the implementation of specific procedures.

[0006] For example, in order to limit the risk of transported loads falling, forklifts are typically equipped with mechanical sensors placed on the vertical uprights of the fork used for lifting and transporting these loads.

[0007] Such mechanical sensors take the form of pivoting stops between a deployed position corresponding to an absent load or a load not bearing against said stop, and a retracted position corresponding to a load bearing against said stop.

[0008] However, when picking up loads from storage racks, it is often difficult for the fork to reach a position that allows the mechanical sensors at the bottom of the fork to detect the presence of the load to be moved. This is particularly true when the load to be picked up is offset inwards relative to the racking. It then sometimes becomes necessary to replace the existing storage racks with racks of a different design.

[0009] To remedy this drawback, one solution is to equip forklifts with rangefinders.

[0010] However, rangefinders that use point measurement cannot detect all types of loads. This can be the case, for example, when the load to be detected includes holes or bores, as is the case with tires.

[0011] US document 2014 / 277691 A1 discloses an autonomous forklift truck according to the preamble of claim 1. Description of the invention

[0012] In view of the above, the aim of the invention is therefore to provide an autonomous forklift capable of remotely and contactlessly detecting loads to be transported, with high detection reliability regardless of the size or shape of the loads to be detected.

[0013] The invention relates to an autonomous forklift comprising a vertically movable fork equipped with at least two arms for lifting loads, a drive system for moving the forklift and a control unit capable of controlling the operation of the drive system to autonomously guide the forklift.

[0014] According to a general characteristic, the forklift truck further includes a non-contact load detection device, said detection device being movable in conjunction with the fork and disposed above the arms of said fork.

[0015] The detection device is capable of emitting a light beam sweeping at least a predefined flat detection zone located above at least one of the fork arms to detect the presence or absence of a load to be lifted.

[0016] According to another general characteristic, the control unit receives information representative of the presence or absence of the load to be lifted in said predefined flat detection zone from the non-contact detection device.

[0017] According to another general characteristic, the control unit is capable of controlling the operation of the drive system and the vertical movement of the fork based on this information.

[0018] The integration of such a contactless detection device makes it possible to detect all types of loads remotely, increasing the level of reliability and safety compared to conventional detection methods.

[0019] It also becomes possible to safely pick up a load "at the end of the forklift's forks." Therefore, there is no need to modify the design of existing storage racking.

[0020] Advantageously, the predefined flat detection zone swept by the light beam emitted by the non-contact detection device is horizontal.

[0021] Preferably, the predefined flat detection zone swept by the light beam emitted by the non-contact detection device is located above the two arms. In this case, the flat detection zone may extend laterally, at least partially, beyond the transverse dimensions of the fork arms.

[0022] Alternatively, the non-contact detection device can scan two distinct flat detection zones, namely a first predefined flat detection zone located above a first fork arm and a second predefined flat detection zone located above a second fork arm different from the first.

[0023] According to another feature, the fork includes at least two uprights supporting the arms, with the contactless detection device being located on one of the uprights.

[0024] In one particular embodiment, the autonomous forklift further includes a stop located on each fork leg and pivotally mounted between a deployed position (corresponding to a load not resting against the stop) and a retracted position (corresponding to a load resting against the stop), the non-contact detection device located on the leg being positioned above the associated stop. Alternatively, the forklift may be provided without these stops.

[0025] The autonomous forklift includes an onboard location device configured to acquire position data from the forklift and communicate with the control unit. Preferably, the non-contact detection device is separate from the location device.

[0026] According to another aspect, the invention relates to a method of lifting and transporting a load by an autonomous forklift as described above.

[0027] The lifting and transport process includes: a step of positioning the fork arms relative to the load, at least a first step of detecting the load by the non-contact detection device, a step of lifting the load if the load is detected in at least a first predefined flat detection zone swept by the light beam emitted by the non-contact detection device during the first detection step, and a step of moving the autonomous forklift and transporting the load.

[0028] For example, the first predefined detection zone is defined by four points delimiting a rectangle.

[0029] In a particular implementation mode, the process may include, before the load lifting step, a second step of detecting the subsequent load by the non-contact detection device, the load lifting step being carried out if the load is detected during the second detection step.

[0030] For example, the load lifting step is carried out after a timing step which itself is carried out after the first detection step.

[0031] Preferably, the second load detection stage can be carried out in at least one second predefined detection zone located inside said first detection zone on the side of the non-contact detection device.

[0032] In one implementation mode, said load detection step is carried out in a flat detection zone which is common to the fork arms.

[0033] In another implementation mode, the load detection step is carried out in two separate, flat detection zones, each specific to one of the two arms of the fork.

[0034] According to one characteristic, the method may include, during the stage of moving the autonomous forklift and transporting the load, a sub-stage of controlling the rotation of the load by the non-contact detection device, the control of the rotation of the load being carried out in relation to each detection zone which is specific to one of the two arms of the fork, the stage of moving the autonomous forklift and transporting the load being stopped if the load is not detected simultaneously in said two detection zones.

[0035] According to another feature, the method may include, during the stage of moving the autonomous forklift and transporting the load, a sub-stage of checking the position of the load by the non-contact detection device, the checking of the position of the load being carried out in relation to said first detection zone, the stage of moving the autonomous forklift and transporting the load being stopped if the load is not detected in said first detection zone.

[0036] According to another feature, the method may include, during the stage of moving the autonomous forklift and transporting the load, a sub-stage of checking the position of the load by the non-contact detection device, the checking of the position of the load being carried out in relation to at least one predefined detection zone representative of a slippage of the load and located outside said first detection zone on the side of the non-contact detection device, the stage of moving the autonomous forklift and transporting the load being stopped if the load is detected in said predefined detection zone representative of a slippage of the load. Brief description of the figures

[0037] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [ Fig 1 ] is a perspective view of an autonomous forklift according to an embodiment of the invention; [ Fig 2 [This schematically illustrates the forklift truck of the] figure 1 during its use; [ Fig 3 ] is a partial top view of the forklift of the figure 1 on which is schematically represented a first charge detection zone; [ Fig 4 ] illustrates the flowchart of a lifting and load transport method according to one implementation method of the invention; [ Fig 5 ] is a partial top view of the forklift of the figure 1 on which are schematically represented two tipping detection zones for a load; [ Fig 6 ] illustrates a flowchart of a lifting and load transport method according to another embodiment of the invention; [ Fig 7 ] is a partial top view of the forklift of the figure 1on which the first and second charge detection zones are schematically represented; [ Fig 8 ] illustrates a flowchart of a lifting and load transport method according to another embodiment of the invention; and [ Fig 9 ] is a partial top view of the forklift of the figure 1 on which is schematically represented a zone for detecting the slippage of a load. Detailed description of at least one embodiment

[0038] On the figure 1 The main elements of an autonomous forklift 1 have been represented according to an embodiment of the invention.

[0039] The architecture of forklift 1 is given by way of example and does not limit the invention to the configuration of the architecture presented. It is understood that the invention also relates to forklifts designed to operate in manual mode and which have been adapted to allow a second mode of operation in automatic mode.

[0040] The autonomous forklift truck 1 illustrated in the figure 1 includes a fork-carrying apron 3 equipped with a fork 4 comprising two arms 4a, 4b spaced laterally and extending forwards. The fork 4 also includes two uprights 4'a, 4'b each supporting one of the arms 4a, 4b.

[0041] The fork arms 4a and 4b are typically used to insert into slots provided in the transport pallets that support the loads to be lifted. The uprights 4'a and 4'b allow the arms 4a and 4b to be raised so that a pallet or other type of load can be lifted, and a pallet or other type of load can be placed or retrieved at a height.

[0042] The fork 4 is capable of translational movement in a vertical plane V defined by the fork carriage 3, along a vertical mast 5 of the forklift. The uprights 4'a, 4'b can slide along the mast 5. The fork arms 4a, 4b are parallel. The longitudinal axes of the arms 4a, 4b of the fork 4 are parallel. These longitudinal axes are oriented parallel to a horizontal axis X, and define a horizontal plane H called the lifting plane. The arms 4a, 4b of the fork 4 are perpendicular to the vertical plane V. The arms 4a, 4b of the fork are also preferably movable laterally relative to each other.

[0043] Alternatively, the arms of the fork 4 could also be telescopic or retractable, and / or angularly orientable around their longitudinal axis.

[0044] In the illustrated embodiment, the trolley 1 further includes a mechanical stop 6 disposed on each of the fork uprights 4'a, 4'b and pivotally mounted between a deployed position corresponding to a load not present or bearing against said stop, and a retracted position corresponding to a load bearing against said stop. The stops 6 are mounted at the lower end of the uprights 4'a, 4'b. On the figure 1 , one of the stops 6 is shown in the deployed position and the other stop is shown in the retracted position for reasons of understanding.

[0045] As is known per se, the trolley 1 is equipped with a drive system 7 enabling the movement of the trolley 1. The drive system includes at least one electric or thermal motor (not shown) enabling the drive of the wheels (not referenced) of the trolley 1.

[0046] The trolley 1 is also equipped with an on-board location device 8, and a control unit 9 ( figure 2 ) onboard receiving information from the location device 8 to autonomously control the movement of the forklift.

[0047] The control unit 9 includes the hardware and software means to control the operation of the drive system 7 according to the information received from the location device 8. The control unit 9 also allows the automatic movement of the fork 4 to be controlled.

[0048] The carriage 1 is also equipped with a non-contact detection device 10, which is located above the arms 4a, 4b of the fork 4. The detection device 10 is fixed to the fork upright 4'a and is situated above the arms 4a, 4b. In the illustrated embodiment, the detection device 10 is fixed to the upright 4'a above the associated stop 6. The non-contact detection device 10 moves in conjunction with the fork upright 4'a. The detection device 10 is separate from the locating device 7.

[0049] As will be described in more detail later, the detection device 10 is capable of emitting a light beam sweeping at least one predefined planar detection zone located above the arms 4a, 4b to detect the presence of a load to be lifted by intersection of the light beam with said load inside said predefined planar detection zone.

[0050] The detection device 10 is configured to acquire position data of the load to be lifted and to transmit to the control unit 9 information indicating the presence or absence of the detected load within the predefined flat detection zone. Based on the information received, the control unit 9 then commands the operation of the drive system 7 and the vertical movement of the fork 4. The detection device 10 can, for example, be a Lidar laser sensor.

[0051] We will now describe, with reference to figures 2 and 3 , the operating principle of the autonomous forklift truck for detecting the presence or absence of a load 12 to be lifted on a rack 13.

[0052] In an initial phase, the control unit 9 commands the operation of the trolley 1 to bring it closer to the rack 13 and to raise the fork arms 4 to position them relative to the load 12 to be lifted. The trolley 1 is controlled by the control unit 9 based on data from the locating device 8. During its movement, the trolley 1 is controlled to maintain a minimum safety distance d from the rack 13. During the initial phase, the trolley 1 is controlled to maintain a minimum horizontal safety distance between the cantilevered end of the fork arms 4 and the rack 13 to allow the arms to safely pass over the rack 13.

[0053] Next, the detection device 10 emits a light beam 14 that sweeps across at least a first predefined flat detection zone 15 located above the arms 4a, 4b of the fork. The vertical projection of the detection zone 15 covers the arms 4a, 4b of the fork and the transverse space separating these arms.

[0054] In the illustrated embodiment, the detection zone 15 is defined by four distinct points delimiting a rectangle, such as points B, C, D, and E of the figure 3 Point A schematically represents the emission point of the light beam 14 at the output of device 10. The detection zone 15 is horizontal here. Alternatively, it might be possible to provide a zone 15 inclined with respect to the horizontal.

[0055] The longer side of the rectangle bounded by points B, C, D, and E has a length y greater than the transverse span of the fork arms 4a and 4b, and the detection zone 15 is centered relative to these arms. In other words, the flat detection zone 15 extends laterally beyond the transverse span of the fork arms 4a and 4b. For reference, the width w of the shorter side of the rectangle bounded by points B, C, D, and E, and therefore the depth of the detection zone 15, can be 50 mm.

[0056] The detection device 10 is configured to detect whether the load 12 is located within the detection zone 15. The load 12 is detected by the device 10 as being present when it intersects the light beam 14 and is located within the detection zone 15. The detection device 10 is capable of detecting that the load is located within the first detection zone 15 by measuring the distance.

[0057] If there is no intersection of the light beam 14 emitted by the device 10 with the load, or if this intersection exists but the detection device 10 detects that the distance separating it from the load 12 is outside the predefined planar detection zone 15, then the device 10 detects an absence of the load 12 in said detection zone.

[0058] A method 20 for lifting and transporting loads using an autonomous forklift truck 1 will now be described. Method 20 is illustrated in figure 4 .

[0059] The process 20 begins with the pre-positioning step 21, during which the control unit 9 drives the trolley 1 to position it directly above the load 12 to be lifted and to position the arms 4a, 4b of the fork 4 vertically at the level of the load.

[0060] During the next positioning step 22, the control unit 9 drives the trolley 1 to bring the arms 4a, 4b closer to the load 12.

[0061] The process then continues with a first step 23 of load detection carried out by device 10. Device 10 detects whether the load 12 is located inside the detection zone 15 ( Figure 3This is the case if the load 12 intersects the light beam 14 emitted by the device 10 and if the load is located within the detection zone 15. The device 10 transmits to the control unit 9 information indicating the presence or absence of the load to be lifted within the detection zone 15.

[0062] If the load 12 is not detected within the detection zone 15 by the device 10, the control unit 9 initializes a time delay value T equal to a predetermined value t in step 24. The predetermined value t can be configured by the control unit 9 according to the travel speed of the trolley 1. The control unit 9 checks, using sensors (not referenced), in the following step 25, whether the minimum safety distance da has been reached or whether the virtual destination point has been reached. If so, the control unit 9 stops the trolley 1 in step 26 to allow for reordering by an operator. If not, the control unit 9 drives the trolley 1 to continue bringing the arms 4a, 4b closer to the load 12, resuming at step 22.

[0063] In the illustrated implementation, if the load 12 is detected within the detection zone 15 by the device 10 during step 23, the control unit 9 decreases the time value T by a predetermined value x during a step 28a, and checks in the following step 28b whether the time value T is less than or equal to 0. If this is not the case, the control unit 9 drives the trolley 1 to continue bringing the arms 4a, 4b closer to the load 12 by resuming at step 22.

[0064] If this is the case, it means that the time delay has elapsed, and the control unit 9 lifts the load by issuing a lifting command in step 29. Then, the control unit 9 commands the movement of the trolley 1 and the transport of the load in step 30. To do this, the control unit 9 uses the information received from the locating device 8 to move the forklift 1 to the intended destination of the load 12 to be transported.

[0065] In the described implementation, the process includes a detection step 23 followed by a timing step. Alternatively, the process may include only the detection step 23 without a timing step.

[0066] In the described implementation mode, the timer initialization T is performed after the detection step 23, when the load is not detected in the detection zone 15. Alternatively, the method could include a timer initialization performed before the positioning step 22.

[0067] In the described implementation mode, at detection step 23, the detection zone 15 of the detection device is common to both arms 4a and 4b of the fork 4. In other words, the vertical projection of the detection zone 15 covers the arms 4a, 4b of the fork and the transverse space separating these arms.

[0068] Alternatively, it might be possible to provide each of the fork arms 4a, 4b with its own initial detection zone. In other words, the detection device 10 ( figure 1 And 2) is capable of emitting a light beam sweeping a first detection zone 15a specific to the arm 4a of the fork and located above this arm 4a and a first zone 15b specific to the arm 4b, located above this arm 4b and distinct from the first detection zone 15a as illustrated in the figure 5 .

[0069] The vertical projection of the first detection zone 15a covers the fork arm 4a, and the vertical projection of the first detection zone 15b covers the arm 4b. The first zone 15a is defined here by four distinct points defining a rectangular area such as B, C, D' and E', and the second zone 15b is defined by four distinct points defining another rectangular area such as B', C', D and E.

[0070] In another variant of the implementation of the process of the figure 4 illustrated at the figure 6, on which the identical steps bear the same references, a second detection step 32 is provided during which the device 10 performs a detection of the charge 12 within a second detection zone 17 illustrated in figure 7 In this implementation mode, there is no time-delay step.

[0071] In the illustrated embodiment, this second detection zone 17 is defined by four distinct points delimiting a rectangle having one long side common to the rectangle defined by points B, C, D, and E of the first detection zone 15. The second detection zone 17 is defined by points E, B, B', and E'. The second detection zone 17 is located inside the first zone 15 and on the side of the detection device 10. The width of the shorter side of the rectangle delimited by points E, B, B', and E' is less than that of the shorter side of the rectangle delimited by points B, C, D, and E.

[0072] Referring again to the figure 6 , if the load 12 is not detected inside the second detection zone 17 during the detection step 32, the process resumes at step 25 then the control unit 9 brings the arms 4a, 4b closer to the load 12 by resuming at step 22 if the minimum safety distance d has not been reached.

[0073] If the load 12 is detected inside the second detection zone 17 during the detection step 32, the control unit 9 lifts the load by issuing a lifting command (step 29), and then commands the movement of the trolley 1 and the transport of the load during step 30.

[0074] In this implementation mode, the first and second detection zones 15, 17 are each common to both arms 4a and 4b of the fork 4. Alternatively, it could also be possible to provide first detection zones specific to each of the arms 4a, 4b as described previously, and second detection zones also specific to each of the arms 4a, 4b.

[0075] In another variant of the implementation of the process illustrated in the figure 8 , on which the identical steps bear the same references, it is provided during step 30 of transport of the load a sub-step 30a of control of the position of the load 12.

[0076] During substep 30a, the detection device 10 can detect the load 12 using the detection zone 15 described previously. If the load is not detected in zone 15, the control unit 9 considers that the transport of the load 12 cannot be carried out safely because this indicates a load slippage and issues a stop command, to allow for reordering by an operator.

[0077] Alternatively, during substep 30a, the detection device 10 can perform load detection 12 using a detection zone 18 representative of load slippage, located outside the first detection zone 15 and corresponding to triangle AFG, as illustrated in the figure 9 . This detection zone 18 is located on the side of the detection device 10 and at a distance from the rectangle defined by points B, C, D and E of the first detection zone 15.

[0078] If the load is detected in the detection zone 18 representative of load slippage, the control unit 9 considers that the load has slipped during transport and issues a stop command for the trolley 1 at step 31 of the process to allow for reordering by an operator.

[0079] In another implementation of the process, it is possible to include, during step 30 of the load transport, a sub-step to check for any potential rotation of the load. This is possible when each of the fork arms 4a, 4b has its own detection zone, as described previously.

[0080] In this case, during step 30 of load transport, if the load is not detected simultaneously in the two detection zones associated with the two arms 4a, 4b of the fork, the control unit 9 considers that the load has undergone a rotation around the vertical axis Z during transport and issues a stop command for the trolley 1 in step 31 of the process to allow for reordering by an operator.

Claims

1. Autonomous lift truck (1) comprising: - a vertically mobile fork (4) equipped with at least two blades (4a, 4b) for lifting loads, - a drive system (7) for moving the lift truck (1), and - a control unit (9) able to command the operation of the drive system (7) for autonomously guiding the lift truck, and able to command the vertical movement of the fork (4), characterized in that the lift truck further comprises: - a contactless load-detection device (10), said detection device (10) being able to move together with the fork (4) and positioned above the blades (4a, 4b) of said fork, the contactless detection device (10) being able to emit a beam of light (14) that sweeps at least a predefined planar detection zone situated above at least one of the blades (4a, 4b) so as to detect the presence or absence of a load that is to be lifted, - the control unit (9) receiving information indicative of the presence or absence of the load that is to be lifted in said predefined planar detection zone and coming from the contactless detection device (10), and being able to command the operation of the drive system (7) and the vertical movement of the fork (4) on the basis of this information.

2. Autonomous lift truck according to Claim 1, wherein said predefined planar detection zone swept by the beam of light (14) emitted by the contactless detection device (10) is horizontal.

3. Autonomous lift truck according to Claim 1 or 2, wherein the fork (4) comprises at least two uprights (4'a, 4'b) supporting the blades (4a, 4b), the contactless detection device (10) being placed on one of the uprights (4'a, 4'b).

4. Autonomous lift truck according to Claim 3, further comprising an end-stop (6) placed on each of the uprights (4'a, 4'b) of the fork and mounted with the ability to pivot between a deployed position corresponding to a load that is absent or not in abutment against said end-stop, and a retracted position corresponding to a load that is in abutment against said end-stop, the contactless detection device (10) placed on said upright (4'a, 4'b) being situated above the associated end-stop (6).

5. Autonomous lift truck according to any one of the preceding claims, comprising an on-board locator device (8) configured to acquire position data pertaining to the position of the lift truck and communicating with the control unit (9), the contactless detection device (10) being distinct from the locator device (8).

6. Method (20, 20') for lifting and transporting a load (12) using an autonomous lift truck (1) according to any one of the preceding claims, characterized in that it comprises: - a step (22) of positioning of the blades (4a, 4b) of the fork (4) with respect to the load (12), - at least a first step (23) of detection of the load (12) by the contactless detection device (10), - a step (29) of lifting of the load if the load (12) is detected in at least a first predefined planar detection zone (15) swept by the beam of light (14) emitted by the contactless detection device (10) in the first detection step, and - a step (30) of movement of the autonomous lift truck and of transporting of the load.

7. Method according to Claim 6, wherein said first predefined detection zone (15) is defined by four points delimiting a rectangle.

8. Method according to Claim 6 or 7, comprising, prior to the step (29) of lifting of the load, a second step (32) of successive detection of the load by the contactless detection device (10), the step of lifting of the load being performed if the load is detected during the second detection step (32).

9. Method according to Claim 6 or 7, wherein the step (29) of lifting of the load is performed after a timeout step (28b) itself performed after the first detection step (23).

10. Method according to Claim 8, wherein the second load-detection step (32) is performed in at least a second predefined detection zone (17) situated inside said first detection zone (15) on the side of the contactless detection device (10).

11. Method according to any one of Claims 6 to 10, wherein said load-detection step is performed in a planar detection zone (15, 17) that is common to the blades (4a, 4b) of the fork.

12. Method according to any one of Claims 6 to 10, wherein said load-detection step is performed in two planar detection zones (15a, 15b) each specific to one of the two blades (4a, 4b) of the fork.

13. Method according to Claim 12, comprising, during the step (30) of movement of the autonomous lift truck and of transporting of the load, a sub-step of checking of the rotation of the load, performed by the contactless detection device (10), the checking of the rotation of the load being performed with respect to each detection zone (15a, 15b) that is specific to one of the two blades (4a, 4b) of the fork, the step (30) of movement of the autonomous lift truck and of transporting of the load being halted if the load is not detected in said two detection zones (15a, 15b) simultaneously.

14. Method according to any one of Claims 6 to 13, comprising, during the step (30) of movement of the autonomous lift truck and of transporting of the load, a sub-step (30a) of checking of the position of the load, performed by the contactless detection device (10), the checking of the position of the load being performed with respect to said first detection zone (15), the step (30) of movement of the autonomous lift truck and of transporting of the load being halted if the load is not detected in said first detection zone (15).

15. Method according to any one of Claims 6 to 13, comprising, during the step (30) of movement of the autonomous lift truck and of transporting of the load, a sub-step (30a) of checking of the position of the load, performed by the contactless detection device (10), the checking of the position of the load being performed with respect to at least one predefined detection zone (18) indicative of a slippage of the load and situated outside said first detection zone (15) on the side of the contactless detection device (10), the step (30) of movement of the autonomous lift truck and of transporting of the load being halted if the load is detected in said predefined detection zone (18) indicative of a slippage of the load.