Autonomous forklift truck for transporting loads, and associated method

Abstract

This autonomous forklift truck (1) comprises: - a vertically movable fork (4) provided with at least two arms (4a, 4b) for lifting loads, - a drive system (7) for moving the forklift truck (1), and - a control unit able to control the operation of the drive system (7) in order to autonomously guide the forklift truck, and able to control the vertical movement of the fork. The truck further comprises a device (10) for contactlessly detecting a load movable together with the fork (4), which device (10) is arranged above the arms (4a, 4b) of the fork. The detection device (10) is able to emit a light beam sweeping at least one predefined planar detection region situated above the arms (4a, 4b) in order to detect the presence or absence of a load. The truck further comprises a means for determining a movement of the truck.

Description

[0001] DESCRIPTION

[0002] TITLE: Autonomous load transport forklift and associated method

[0003] Technical field

[0004] The present invention relates to the field of autonomous vehicles for the automated transport of loads, such as autonomous forklifts.

[0005] State of the prior art

[0006] Autonomous vehicles for transporting loads are increasingly used to increase productivity and improve logistics management in factories and warehouses.

[0007] Automated forklifts are an example of such vehicles and allow, for example, loading, transporting and positioning a load at height without human intervention.

[0008] However, in environments such as factories or warehouses, human intervention is still necessary to complement automated operations, for example to monitor the smooth running of these operations or to perform tasks that cannot be performed by machines alone. These environments are therefore shared between humans and autonomous machines.

[0009] The safety of people is fundamental in such working environments and therefore requires the implementation of specific procedures.

[0010] For example, in order to limit the risk of transported loads falling, forklifts are traditionally equipped with mechanical sensors placed on the vertical uprights of the fork used for lifting, transporting and depositing these loads.

[0011] Such mechanical sensors are in the form of pivoting stops between a deployed position corresponding to a load that is absent or not resting against said stop, and a retracted position corresponding to a load resting against said stop. However, these mechanical sensors installed at the bottom of the deck do not make it possible to ensure when depositing a load that the deposit has been correctly carried out on the storage rack, nor to ensure when taking a load from the rack that this taking has also been correctly carried out.

[0012] This creates the risk of accidents.

[0013] Indeed, after placing the load on a rack, if the fork arms are not correctly removed from the pallet supporting this load and remain in contact with it, then there is a significant risk of the load falling when the truck moves back.

[0014] This risk of falling also exists when picking up a load from a rack if the fork arms of the truck are not positioned correctly in relation to the load, then the load can be pushed off the rack when the truck moves forward.

[0015] Statement of the invention

[0016] In view of the above, the aim of the invention is therefore to propose an autonomous forklift truck capable of increasing the level of reliability and safety of depositing and loading operations from a storage rack.

[0017] The subject of the invention is an autonomous forklift comprising a vertically movable fork and provided with at least two arms for lifting loads, a drive system for moving the forklift, a control unit capable of controlling the operation of the drive system to autonomously guide the forklift and capable of controlling the vertical movement of the fork.

[0018] According to a general characteristic, the forklift truck further comprises a device for contactless detection of a load, said detection device being movable jointly with the fork and arranged above the arms of said fork. The contactless detection device is capable of emitting a light beam scanning at least one predefined flat detection zone located above the arms to detect the presence or absence of a load. According to another general characteristic, the forklift truck further comprises a means for determining a movement of the forklift truck. The determination means is capable of acquiring information representative of the movement of the forklift truck from a position for depositing or picking up a load from the forklift truck, said position being recorded by the control unit.

[0019] According to another general characteristic, the control unit receives representative information from the determination means and information representative of the presence or absence of the load in said predefined flat detection zone from the contactless detection device.

[0020] According to another general characteristic, the control unit is able to control the operation of the drive system and the vertical movement of the fork based on this information.

[0021] With such an autonomous forklift, it becomes possible to ensure, after placing a load on a storage rack, that the vehicle reverses without the risk of the load falling.

[0022] It also becomes possible to ensure, when taking a load from a storage rack, that the vehicle moves forward without risk of pushing and therefore falling of the load.

[0023] In addition, the integration of such a contactless detection device makes it possible to detect any type of load remotely.

[0024] Advantageously, the determination means comprises at least one rotary encoder capable of measuring the rotation of at least one wheel of the forklift.

[0025] The integration of such a rotary encoder promotes the achievement of good precision in controlling the movement of the carriage.

[0026] Advantageously, said predefined flat detection zone scanned by the light beam emitted by the contactless detection device is horizontal.

[0027] Preferably, said predefined flat detection zone scanned by the light beam emitted by the contactless detection device is located above the two arms. In this case, said flat detection zone can extend laterally at least partly beyond the transverse dimensions of said fork arms.

[0028] Alternatively, the contactless detection device may scan two distinct planar detection zones, namely a first predefined planar detection zone located above a first arm of the fork and a second predefined planar detection zone located above a second arm of the fork different from the first.

[0029] According to another characteristic, the fork comprises at least two uprights supporting the arms, the contactless detection device being arranged on one of the uprights.

[0030] The autonomous forklift comprises an on-board location device configured to acquire position data of the forklift and communicating with the control unit. Preferably, the non-contact detection device is separate from the location device.

[0031] Preferably, the determining means is separate from the locating device. Alternatively, however, it could be envisaged that the locating device forms the determining means.

[0032] In a particular embodiment, the self-guided forklift truck may further comprise a stop arranged on each of the fork uprights and pivotally mounted between a deployed position corresponding to a load that is absent or not bearing against said stop and a retracted position corresponding to a load bearing against said stop, the contactless detection device arranged on said upright being located above the associated stop. Alternatively, it remains possible to provide that the truck is not equipped with these stops.

[0033] According to another aspect, the invention relates to a method for transporting and depositing a load by an autonomous forklift as described above.

[0034] The transport and removal process includes:

[0035] - a step of dropping off the load in which the forklift has reached a load dropping position, - a step of recording the position of the forklift in said load dropping position as a reference position,

[0036] - a step of charge detection by the contactless detection device in at least one predefined flat detection zone,

[0037] - if the load is not detected in the detection step, a step of reversing the forklift by a predetermined reversing distance which is controlled by means of the information from the determination means,

[0038] - after the step of reversing the forklift by the predetermined reversing distance, a step of load detection by the contactless device in at least one predefined flat detection zone which is contiguous to said previous flat detection zone, which is located on the side opposite the contactless detection device with respect to said previous flat detection zone, and which has a lateral dimension equal to the value of reversing of the forklift carried out in the reversing step,

[0039] - if the load is not detected in the immediately preceding detection step, a repetition of the reversing step and the detection step until a load detection is achieved in at least one predefined flat clearance zone relative to the free end of the fork arms, and

[0040] - a step of movement of the forklift which is triggered at least as a function of the presence or absence of load in said predefined flat clearance zone.

[0041] With this method of depositing, safety is improved by making it possible to check, when depositing the load on a storage rack, that this load remains in place on the rack and is not pulled by the truck as it reverses.

[0042] For example, the predefined flat clearance area may be located in front of the free end of the fork legs.

[0043] Alternatively, the predefined flat clearance zone may be located at the rear of the free end of the fork arms, and the forklift movement step is triggered if the absence of a load in said clearance zone is detected and if the sum of the values ​​of the forklift's reversal from the drop-off position is greater than the distance separating the free end of the fork arms from the part of said detection zone of the step which is located on the side of the detection device.

[0044] Advantageously, the forklift's recoil during the reversing steps is of a constant value. Alternatively, it remains possible to provide variable recoil values.

[0045] In a particular embodiment, the steps of reversing the forklift are carried out continuously without stopping, said detection zones and said clearance zone being activated by the detection device successively according to the constant reversing value of the forklift.

[0046] In another embodiment, it could be possible to provide that the steps of reversing the forklift are carried out incrementally with a stopping phase between two successive reversings.

[0047] The invention also relates to a method for lifting and transporting a load by an autonomous forklift as described above.

[0048] The lifting and transport process includes:

[0049] - a step of positioning the fork arms relative to the load to be lifted in a load-taking position,

[0050] - a step of load detection by the contactless detection device in at least one predefined flat detection zone relative to the free end of the fork arms,

[0051] - if the load is detected in the detection step, a step of recording the position of the forklift in said load detection position as a reference position,

[0052] - a step of advancing the forklift by a predetermined advancement distance which is controlled by means of the information from the determination means,

[0053] - after the step of advancing the forklift by the predetermined advancement distance, a step of detecting the load by the contactless detection device in at least one predefined flat detection zone which is contiguous to said previous flat detection zone, which is located on the side of the contactless detection device with respect to said previous flat detection zone, and which has a lateral dimension equal to the value of the advancement of the forklift carried out in the advancement step,

[0054] - if the load is detected in the previous detection step, a repetition of the advancement step and the detection step until a load detection is carried out in at least one predefined flat gripping zone,

[0055] - a step of lifting the load if the load is detected in said predefined flat gripping zone, and

[0056] - after the lifting step, a step of moving the forklift and transporting the load.

[0057] With this lifting method, safety is improved by making it possible to check, when picking up the load from a storage rack, that the load remains in place on the rack and is not pushed by the truck as it moves forward.

[0058] Preferably, the advancement of the forklift carried out during the advancement stages is of constant value. Alternatively, it remains possible to provide variable advancement values.

[0059] In a particular embodiment, the steps of advancement of the forklift are carried out continuously without stopping, said detection zones and said gripping zone being activated by the detection device successively according to the constant advancement value of the forklift.

[0060] In another embodiment, it could be possible to provide that the steps of advancement of the forklift are carried out incrementally with a stopping phase between two successive advancements.

[0061] According to one feature, the predefined flat detection area is defined by four points delimiting a rectangle.

[0062] In one embodiment, said load detection step is carried out in a flat detection zone which is common to the fork arms. In another embodiment, said load detection step is carried out in two separate flat detection zones, each specific to one of the two fork arms.

[0063] Brief description of the drawings

[0064] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0065] [Fig 1] is a perspective view of an autonomous forklift according to an exemplary embodiment of the invention;

[0066] [Fig 2] schematically illustrates the forklift of Figure 1 in use;

[0067] [Fig 3] is a partial top view of the forklift of Figure 1 in which a first load detection zone is schematically represented;

[0068] [Fig 4] illustrates the flowchart of a method for transporting and depositing a load according to an embodiment of the invention;

[0069] [Fig 5] is a partial top view of the forklift of Fig. 1 showing schematically a load sensing area contiguous to the previous load sensing area shown in Fig. 3;

[0070] [Fig 6A] [Fig 6B] [Fig 6C] [Fig 6D] [Fig 6E] [Fig 6F] [Fig 6G] are partial top views of the forklift of Figure 1 showing schematically successive and contiguous load detection zones used in the method illustrated in Figure 4;

[0071] [Fig 6H] is a partial top view of the forklift of Fig. 1 showing schematically a clearance area used in the method illustrated in Fig. 4;

[0072] [Fig 7] illustrates the flowchart of a method for lifting and transporting a load according to an embodiment of the invention; and

[0073] [Fig 8A] [Fig 8B] [Fig 8C] [Fig 8D] [Fig 8E] [Fig 8F] [Fig 8G] [Fig 8H] [Fig 81] are partial top views of the forklift of Figure 1 showing schematically successive and contiguous load sensing zones used in the method illustrated in Figure 7; and

[0074] [Fig 8J] is a partial top view of the forklift of Figure 1 showing schematically a load-taking area used in the method illustrated in Figure 7.

[0075] Detailed description of at least one embodiment

[0076] Figure 1 shows the main elements of an autonomous forklift 1 according to one embodiment of the invention.

[0077] The architecture of the forklift 1 is given by way of example and does not limit the invention to the sole configuration of the architecture presented. It is understood that the invention also relates to forklifts intended to operate in manual mode and which have been adapted to allow a second mode of operation in autonomous mode.

[0078] The self-contained forklift 1 illustrated in Figure 1 comprises a fork carriage 3 provided with a fork 4 comprising two arms 4a, 4b spaced laterally and extending forward. The fork 4 also comprises two uprights 4'a, 4'b each supporting one of the arms 4a, 4b.

[0079] The arms 4a, 4b of the fork are generally used to insert into insertion tunnels provided in the transport pallets supporting the loads to be lifted. The uprights 4'a, 4'b allow the arms 4a, 4b to be raised in order to be able to lift a pallet to be transported or another type of load and to be able to place or pick up a pallet or another type of load at height.

[0080] The fork 4 is able to move in translation in a vertical plane V defined by the fork-carrying carriage 3, along a vertical mast 5 of the truck. The uprights 4'a, 4'b can slide along the mast 5. 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.

[0081] Alternatively, the arms of the fork 4 could be telescopic or retractable, and / or angularly orientable around their longitudinal axis.

[0082] In a manner known per se, the trolley 1 is equipped with a drive system 7 allowing the trolley 1 to move. The drive system comprises at least one electric or thermal motor (not shown) allowing the wheels 18 of the trolley 1 to be driven.

[0083] The truck 1 is also equipped with an on-board location device 8, and an on-board control unit 9 (figure 2) receiving information from the location device 8 to autonomously control the movement of the forklift.

[0084] The control unit 9 comprises the hardware and software means for controlling the operation of the drive system 7 based on the information received from the location device 8. The control unit 9 also makes it possible to control the autonomous movement of the fork 4.

[0085] The trolley 1 is further equipped with a means 11 for determining a movement of the forklift 1, said determining means 11 being configured to acquire information representative of the movement of the trolley 1 and to transmit it to the control unit 9. In a preferred embodiment, the determining means 11 comprises at least one rotary encoder capable of measuring the rotation of at least one wheel 18 of the forklift 1. The encoder is capable of determining the value of the movement of the forklift 1 as a function of the detected number of revolutions of the associated wheel 18.

[0086] The carriage 1 is also equipped with a contactless detection device 10 which is arranged above the arms 4a, 4b of the fork 4. The detection device 10 is fixed to the upright 4'a of the fork and is located above the arms 4a, 4b. The contactless detection device 10 is movable together with the upright 4'a of the fork. The detection device 10 is separate from the locating device 8 and the determination means 11.

[0087] As will be described in more detail below, the detection device 10 is capable of emitting a light beam scanning at least one predefined flat 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 flat detection zone.

[0088] 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 representative of the presence or absence of the load detected within the predefined flat detection zone. Depending on the information received, the control unit 9 then controls the operation of the drive system 7 and the vertical movement of the fork 4. The detection device 10 may for example be a laser sensor of the Lidar type.

[0089] We will now describe with reference to figures 2 and 3 the operating principle of the autonomous forklift 1 for detecting the presence or absence of a load 12 to be placed on a shelf 13.

[0090] In an initial phase, the control unit 9 controls the operation of the carriage 1 to bring it closer to the rack 13 and to raise the arms of the fork 4 carrying the load to be deposited in order to position it relative to the rack 13. The carriage 1 is controlled by the control unit 9 according to the data from the location device 8. During its movement, the carriage 1 is controlled to maintain a minimum safety distance d relative to the rack 13. During the initial phase, the carriage 1 is controlled to maintain a minimum horizontal safety distance between the cantilevered end of the arms of the fork 4 and the rack 13 in order to allow the arms of the fork 4 to pass safely above the rack 13.

[0091] The control unit 9 can use the information transmitted by the determination means 11 to precisely control the movement of the carriage 1 in addition to the data from the location device 8.

[0092] After this initial phase, the detection device 10 emits a light beam 14 scanning at least one predefined flat detection zone 15a 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.

[0093] In the illustrated embodiment, the detection zone 15a is defined by four distinct points delimiting a rectangle, such as points B, C, D and E in FIG. 3. Point A schematically represents the emission point of the light beam 14 at the output of the device 10. The detection zone 15a is here horizontal. Alternatively, it could be possible to provide a zone 15a inclined relative to the horizontal.

[0094] The long side of the rectangle delimited by points B, C, D and E has a length y greater than the transverse dimensions of the arms 4a, 4b of the fork, and the detection zone 15a is centered relative to these arms. In other words, the flat detection zone 15a extends laterally beyond the transverse dimensions of the arms 4a, 4b of the fork. As an indication, the width w of the short side of the rectangle delimited by points B, C, D and E, and therefore the depth of the detection zone 15a, may be equal to 50 mm.

[0095] The detection device 10 is configured to detect whether the load 12 is within the detection zone 15a. The load 12 is detected by the device 10 as being present when it intersects the light beam 14 and is within the first detection zone 15. The detection device 10 is capable of detecting that the load is within the first detection zone 15 by a distance measurement.

[0096] If there is no intersection of the light ray 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 flat detection zone 15, then the device 10 detects an absence of the load 12 in said detection zone.

[0097] A method 20 for depositing a load by the autonomous forklift 1 will now be described. The method 20 is illustrated in Figure 4.

[0098] The method 20 begins with the step 21 of depositing the load 12, during which the control unit 9 controls the carriage 1 to reach a position for depositing the load. Once the carriage 1 has reached the position for depositing the load, the control unit 9 controls the movement of the arms 4a, 4b relative to the rack 13 in order to deposit the load 12 there. During this phase, the control unit 9 controls the lowering of the load 12 above the rack 13 until the load 12 comes into contact with the part of the rack 13 intended to receive the load 12. The control unit 9 then continues the lowering of the arms 4a, 4b inducing a relative vertical movement between the arms 4a, 4b and the load 12 meaning that the latter is no longer in contact with the arms 4a, 4b and rests entirely on the rack 13.

[0099] The method 20 continues with a step 22 of recording the position of the forklift 1 in the load deposit position as a reference position.

[0100] In the next load detection step 23, the device 10 detects whether the load 12 is absent from the predefined plane detection zone 15a (figure 3).

[0101] If the presence of the load is detected in zone 15a, the control unit 9 stops the trolley 1 at step 23' to allow reordering by an operator.

[0102] If the absence of the load is detected in the zone 15a, the method continues with a step 24 of reversing. During this step 24, the control unit 9 controls the carriage 1 to make it reverse by a predetermined reversing distance away from the shelf 13 and the load 12. The reversing distance is of a predefined value, and may for example be equal to 50 mm. The control unit 9 controls the reversing of the carriage 1 by means of the information from the determination means 11. Alternatively, the method 20 could comprise an additional reversing step carried out before the detection step 23.

[0103] After the step 24 of reversing the forklift 1 by the predetermined reversing distance, the method continues with a step 25 of load detection in which the device 10 carries out the load detection in a new predefined planar detection zone 15b (figure 5) which is contiguous to the previous planar detection zone 15a considering the elongation axis of the arms 4a, 4b of the fork. The predefined planar detection zone 15b is located on the side opposite the detection device 10 with respect to the previous planar detection zone 15a and has a lateral dimension w equal to the value of the reversing of the forklift 1 carried out in the reversing step 24. In figure 5, the predefined planar detection zone 15b corresponds to the rectangle CC b D b D. Given the contiguous nature of zone 15b with respect to zone 15a, rectangles BCDE and CC b D b D have one of their large sides in common, namely the CD side.

[0104] If the presence of the load in zone 15b is detected at step 25, the control unit 9 stops the trolley 1 at step 25' to allow reordering by an operator.

[0105] If the absence of the load in zone 15b is detected at step

[0106] 25 of load detection, the method 20 continues with a repetition

[0107] 26 of the step 24 of recoil and of the step 25 of detection, until the detection device 10 carries out a load detection in a zone 16 (figure 6H) of predefined plane clearance relative to the free end of the arms 4a, 4b of the fork.

[0108] In the illustrated embodiment, the clearance zone 16 corresponds to a predetermined zone which is located in front of the arms 4a, 4b of the fork and which is defined as being a clearance position of the fork relative to the load 12 in which there is no risk of interference. In Figure 6H, the clearance zone 16 defined by four points F, G, H, I defining a rectangle located in front of the arms 4a, 4b of the fork.

[0109] Alternatively, it could be possible to define another clearance zone 16 relative to the free end of the arms 4a, 4b of the fork, for example an area which is further away from the free end of the arms 4a, 4b of the fork or even an area having a different width w.

[0110] As previously indicated, if the absence of charge in the zone 15b is detected in the charge detection step 25, the method 20 continues by repeating the backing off and detection steps.

[0111] Thus, after a new reversal of the forklift 1 controlled by the control unit 9 by a reversal distance of value equal to that of step 24, a new detection step is carried out in a new predefined flat detection zone 15c (figure 6A) contiguous to the previous flat detection zone 15b. The predefined flat detection zone 15c is located on the side opposite the detection device 10 with respect to the previous flat detection zone 15b and has a lateral dimension w equal to the value of the reversal of the forklift 1 which has just been carried out.

[0112] If the presence of the load in zone 15c is detected, the control unit 9 stops the trolley 1 to allow an operator to put it back in order. If the absence of the load in zone 15c is detected, the process 20 continues.

[0113] The repetition of the recoil and detection steps continues identically with detection zones 15d (Figure 6B) to 15i (Figure 6G) up to the plane clearance zone 16 (Figure 6H).

[0114] The reversing steps of the forklift 1 are carried out continuously without stopping. The detection zones 15a to 15i and the clearance zone 16 are activated by the detection device 10 successively according to the constant reversing value of the forklift.

[0115] If the load is absent from the clearance zone 16 when the load detection is carried out in this zone 16, the method proceeds to step 27 of moving the forklift 1, which can then be assigned to another task.

[0116] On the contrary, if the load is present in the clearance zone 16 when this detection occurs, the control unit 9 stops the trolley 1 at step 26' to allow an operator to put it back in order.

[0117] In another embodiment, it could be possible to provide that the method proceeds to step 27 if the load is present in the clearance zone 16 when the load detection is carried out in this zone 16. With such an embodiment, it is preferable to provide a larger spacing separating the free end of the arms 4a, 4b of the fork and the zone 16.

[0118] In the described embodiment, the method 20 comprises a step of detecting load in the clearance zone 16 which is located in front of the arms 4a, 4b of the fork. As indicated previously, it could be possible to define another clearance zone 16.

[0119] For example, the clearance zone 16 could be defined as being at the rear of the free end of the fork arms 4a, 4b. In this case, the vertical projection of the clearance zone 16 is located on the fork arms 4a, 4b.

[0120] With a clearance zone 16 thus defined, the method moves to step 27 of moving the forklift if the load is absent from this zone 16 and if the sum of the values ​​of the forklift's recoil from the deposit position is greater than the distance separating the free end of the arms 4a, 4b of the fork from the large side BE of the rectangle of the detection zone 15a.

[0121] In the described embodiment, a single recording step, i.e. a reference taking step, of the position of the forklift in the load depositing position as a reference position is provided. Alternatively, it is also possible to provide a reference taking step of the position of the forklift after each reversal of the predetermined reversing distance.

[0122] A method 30 for lifting and transporting a load by the autonomous forklift 1 will now be described. The method 30 is illustrated in Figure 7.

[0123] The method 30 begins with the positioning step 31, during which the control unit 9 controls the carriage 1 to position the arms 4a, 4b relative to the rack 13 in a position for taking up the load 12. Before and during this step, the load 12 rests on the rack.

[0124] The method 30 continues with a step 32 of load detection by the detection device 10 in a predefined planar detection zone 17a (FIG. 8A). In the illustrated embodiment, the zone 17a corresponds to a predetermined zone which is located at the front of the arms 4a, 4b of the fork. In FIG. 8A, the zone 17a is defined by four points J, K, L and M delimiting a rectangle located at the front of the arms 4a, 4b of the fork.

[0125] If the presence of a load is not detected in the predefined flat detection zone 17a, the control unit 9 stops the trolley 1 at step 32' to allow an operator to put it back in order.

[0126] If the presence of a load is detected in the zone 17a, the method 30 continues with a step 33 of recording the position of the forklift 1 in the load detection position 12 as a reference position, then a step 34 of advancing.

[0127] During the advancement step 34, the control unit 9 controls the carriage 1 to make it advance by a predetermined advancement distance by approaching the shelf and the load. The value of this advancement is of a predefined value, and can for example be equal to 50 mm. The control unit 9 controls the advancement of the carriage 1 by means of the information from the determination means 11.

[0128] Alternatively, the method 30 could comprise an additional advancement step carried out before the reference-taking step 33.

[0129] After the step 34 of advancing the forklift 1 by the predetermined recoil distance, the method 30 continues with a step 35 of detecting the load in which the detection device 10 carries out the load detection in a new predefined plane detection zone 17b (FIG. 8B) which is contiguous to the previous plane detection zone 17a considering the elongation axis of the arms 4s, 4b of the fork. The predefined plane detection zone 17b is located on the side of the detection device 10 with respect to the previous plane detection zone 17a and has a lateral dimension w equal to the value of the advancement of the forklift 1 carried out in the advancement step 34. In FIG. 8B, the predefined plane detection zone 17b corresponds to the rectangle J b JMM b, Given the contiguous nature of zone 17b with respect to zone 17a, the rectangles J b JMM b and JKLM have one of their big common sides, namely the JM side.

[0130] If the absence of the load is detected in zone 17b, the control unit 9 stops the trolley 1, during step 35', to allow an operator to put it back in order.

[0131] If the presence of the load is detected in the zone 17b, the method 30 continues with a repetition 36 of the advancement step 34 and the detection step 35, until the detection device 10 carries out a load detection in a predefined flat grip zone 18 relative to the vertical uprights of the fork which is illustrated in FIG. 8J.

[0132] In the illustrated embodiment, the gripping zone 18 corresponds to a predetermined zone which is located on the side of the vertical uprights of the fork and which is defined as being a safe load-taking position. In Figure 8J, the gripping zone 18 is defined by four points P, R, S and Q defining a rectangle located near the vertical uprights of the fork.

[0133] As previously indicated, if the presence of the load in the zone 17b is detected at the load detection step 35, the method 30 continues by repeating the advancement and detection steps.

[0134] Thus, after a new advancement of the carriage 1 controlled by the control unit 9 by a distance of advancement of value equal to that of step 34, a new detection step is carried out in a new predefined flat detection zone 17c (figure 8C) which is contiguous to the previous flat detection zone 17b. The predefined flat detection zone 17c is located on the side of the detection device 10 relative to the previous flat detection zone 17b and has a lateral dimension w equal to the value of the advancement of the forklift 1 which has just been carried out. If the absence of the load in the zone 17c is detected, the control unit 9 stops the carriage 1 to allow an operator to put it back in order. If the presence of the load in the zone 17c is detected, the method 30 continues.

[0135] The repetition of the advancement and detection steps continues identically with zones 17d (Figure 8D) to 17i (Figure 8I) up to the grip zone 18 as shown in Figure 8J.

[0136] The advancement steps of the forklift 1 are carried out continuously without stopping. The detection zones 17a to 17i and the gripping zone 18 are activated by the detection device 10 successively according to the constant advancement value of the forklift.

[0137] If the load is absent from the gripping zone 18 when the load detection is carried out in this zone 18, the control unit 9 stops the trolley 1 at step 36' to allow reordering by an operator.

[0138] On the contrary, if the load is present in the gripping zone 18 during this detection, the method goes to step 37 in which the control unit 9 carries out the lifting of the load by issuing a lifting instruction.

[0139] After lifting the load 12, the method 30 continues with the step 38 of moving the forklift and transporting the load 12.

[0140] In the described embodiment, a single recording step, i.e. a reference taking step, of the position of the forklift in the load detection position as a reference position is provided. Alternatively, it is also possible to provide a reference taking step of the position of the forklift after each advance of the predetermined advance distance.

[0141] In each of the described embodiments, the detection steps are carried out with detection zones of the detection device which are each common to the two arms 4a and 4b of the fork. Alternatively, it could be possible to provide, at each detection step and for each of the arms 4a, 4b of the fork, a detection zone specific to it. In this case, at each detection step, the detection device emits a light beam scanning a detection zone specific to the arm 4a of the fork and located above this arm 4a, and a zone specific to the arm 4b, located above this arm 4b and distinct from the detection zone specific to the arm 4a.

Claims

DEMANDS 1. Self-contained forklift (1) comprising: - a vertically movable fork (4) equipped with at least two arms (4a, 4b) for lifting loads, - a drive system (7) for moving the forklift (1), and - a control unit (9) capable of controlling the operation of the drive system (7) to autonomously guide the forklift, and capable of controlling the vertical movement of the fork (4), characterized in that the forklift (1) further comprises: - a non-contact load detection device (10), said load detection device (10) being movable in conjunction with the fork (4) and disposed above the arms (4a, 4b) of said fork, the non-contact load detection device (10) being capable of emitting a light beam (14) sweeping at least a predefined flat detection zone located above the arms (4a, 4b) to detect the presence or absence of a load, and - a means of determining (11) a movement of the forklift (1), said means of determining (11) being capable of acquiring information representative of the movement of the forklift (1) from a position of depositing or taking up a load of the forklift (1) recorded by the control unit (9), the control unit (9) receiving information representative of the movement of the forklift (1) from the means of determining (11) and information representative of the presence or absence of the load in said predefined planar detection zone from the non-contact detection device (10), and being capable of controlling the operation of the drive system (7) and the vertical movement of the fork (4) according to this information.

2. Autonomous forklift according to claim 1, wherein the determination means (11) comprises at least one rotary encoder capable of measuring the rotation of at least one wheel (18) of the forklift.

3. Autonomous forklift according to claim 1 or 2, wherein said predefined flat detection zone swept by the light beam (14) emitted by the non-contact detection device (10) is horizontal.

4. Autonomous forklift according to any one of the preceding claims, wherein the fork (4) comprises at least two uprights (4' a, 4'b) supporting the arms (4a, 4b), the non-contact detection device (10) being disposed on one of the uprights (4' a, 4'b).

5. Autonomous forklift according to any one of the preceding claims, comprising an on-board location device (8) configured to acquire position data of the forklift and communicating with the control unit (9), the non-contact detection device (10) being separate from the location device (8).

6. Autonomous forklift according to claim 5, wherein the determination means (11) is separate from the localization device (8).

7. Method (20) of transporting and depositing a load (12) by a self-propelled forklift (1) according to any one of the preceding claims, characterized in that it comprises: - a) a loading (21) drop-off stage (12) in which the forklift has reached a loading drop-off position, - b) a step (22) of recording the position of the forklift (1) in said load placement position as a reference position, - c) a step (23) of charge detection by the non-contact detection device (10) in at least one predefined planar detection zone (15a), - d) if the load is not detected at the detection step (23), a reversing step (24) of the forklift (1) by a predetermined reversing distance which is controlled via information from the determination means (11), - e) after the step (24) of reversing the forklift (1) by the predetermined reversing distance, a step (25) of load detection by the non-contact detection device (10) in at least one predefined planar detection zone (15b) which is contiguous to said previous planar detection zone (15a), which is located on the opposite side of the non-contact detection device (10) with respect to said previous planar detection zone (15a), and which has a lateral dimension equal to the reversing value of the forklift (1) performed in the reversing step (24), - f) if the load is not detected in the immediately preceding detection step (25), a repetition (26) of the recoil step (24) and the detection step (25) until a load is detected in at least one predefined flat clearance area (16) relative to the free end of the fork arms (4a, 4b), and - g) a step (27) of forklift movement which is triggered at least according to the presence or absence of load in said predefined flat clearance area (16).

8. Method according to claim 7, wherein said predefined flat clearance zone (16) is located at the front of the free end of the fork arms (4a, 4b).

9. Method according to claim 7, wherein said predefined flat clearance zone (16) is located at the rear of the free end of the fork arms (4a, 4b), and the forklift travel step (27) is triggered if the absence of load in said clearance zone (16) is detected and if the sum of the forklift recoil values ​​from the drop-off position is greater than the distance separating the free end of the fork arms (4a, 4b) from the part of said detection zone (15a) of step (23) which is located on the side of the detection device (10).

10. Method according to any one of claims 7 to 9, wherein the recoil of the forklift truck during the recoil steps (24) is of constant value.

1. A method according to claim 10, wherein the forklift reversing steps (24) are carried out continuously without stop, said detection zones (15a, 15b) and said clearance zone (16) being activated by the detection device (10) successively according to the constant recoil value of the forklift.

12. A method (30) for lifting and transporting a load (12) by a self-propelled forklift (1) according to any one of claims 1 to 6, characterized in that it comprises: a) a step (31) of positioning the arms (4a, 4b) of the fork (4) relative to the load (12) to be lifted in a load-picking position, b) a step (32) of detecting the presence of a load by the non-contact detection device (10) in at least one predefined planar detection zone (17a) relative to the free end of the arms (4a, 4b) of the fork, c) if the load is detected in the detection step (32), a step (33) recording the position of the forklift (1) in said load-sensing position as the reference position, (d) a step (34) of the forklift (1) advancing a predetermined distance which is controlled by means of information from the determination means (11), (e) after the step (34) of the forklift (1) advancing the predetermined distance, a step (35) of the load being detected by the non-contact sensing device (10) in at least one predefined planar sensing zone (17b) which is contiguous to said previous planar sensing zone (17a), which is located on the side of the non-contact sensing device (10) with respect to said previous planar sensing zone (17a), and which has a lateral dimension equal to the value of the forklift (1) advance made in the step (34) advancement, (f) if the load is detected in the previous detection step (35), a repetition (36) of the advancement step (34) and the detection step (35) until a load is detected in at least one predefined flat grip zone (18), (g) a load lifting step (37) if the load is detected in said predefined flat grip zone (18), and h) after the lifting step (37), a step (38) of moving the forklift and transporting the load.

13. Method according to claim 12, wherein the advancement of the forklift during the advancement steps (34) is of constant value.

14. Method according to claim 13, wherein the forklift advancement steps (34) are carried out continuously without stopping, said detection zones (17a, 17b) and said gripping zone (18) being activated by the detection device (10) successively according to the constant advancement value of the forklift.

15. A method according to any one of claims 7 to 14, wherein said predefined planar detection zone is defined by four points delimiting a rectangle.

16. Method according to any one of claims 7 to 15, wherein said load detection step is carried out in said planar detection zone which is common to both arms (4a, 4b) of the fork.

17. A method according to any one of claims 7 to 15, wherein said load detection step is carried out in two planar detection zones, each specific to one of the two arms (4a, 4b) of the fork.

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