Method of lifting and transporting a load using a self-propelled lifting forklift

Abstract

This method (20) for lifting and transporting a load comprises: a step (21) of receiving a mission by the trolley, including a theoretical value for at least one dimension of said load; a step (22) of moving the trolley in front of the load to be lifted and transported; a step (23) of acquiring at least one image of the load by at least one camera mounted on the trolley; a step (24) of determining an actual value for said dimension of the load from said image obtained in the acquisition step; a step (26) of comparing the actual value and the theoretical value of said dimension; and a step (27) of stopping the trolley if the difference between the actual value of said dimension and its theoretical value exceeds a predefined limit value. (See Figure 4 for abbreviations)

Description

Title of the invention: Method for lifting and transporting a load by a self-propelled lifting forklift Technical field

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

[0002] Autonomous vehicles for transporting loads are increasingly used to increase productivity and to 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 proper execution 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 persons is fundamental in such working environments and therefore requires the implementation of specific procedures.

[0006] For example, during the operations of taking a load from a storage rack that can accommodate different loads, particularly in terms of dimensions, it is possible that the load actually present on the rack does not correspond to the load to be taken by the autonomous forklift according to the mission assigned to the latter by a management system managing the flows of the warehouse.

[0007] If this is the case, there is a risk of an accident. Statement of the invention

[0008] In view of the above, the object of the invention is to increase the safety of lifting and load transport operations by an autonomous forklift.

[0009] The invention relates to a method of lifting and transporting a load by an autonomous forklift comprising a vertically movable fork equipped with at least one arm.

[0010] The process comprises:

[0011] - a stage of receiving by the cart an assigned task of moving the load to be lifted and transported which includes a theoretical value of at least one dimension of said load;

[0012] - a step of moving the autonomous forklift in front of the load to to lift and to carry

[0013] - a step of acquiring at least one image of the charge by at least one camera fixed on the autonomous forklift, centered with respect to the fork and having a viewing axis oriented forwards along a longitudinal axis of said forklift;

[0014] - a step of determining an actual value of said dimension of the load at based on the image obtained during the acquisition stage,

[0015] - a step of comparing the actual value of said dimension of the load determined at the determination stage and the theoretical value of said dimension of the load received at the reception stage, and

[0016] - a carriage stop step if the difference between the actual value of said dimension and its The theoretical value is greater in absolute value than a predefined limit value, or

[0017] - a lifting and transport step of the load if the difference between the actual value of said dimension and its theoretical value is less than or equal in absolute value to the predefined limit value.

[0018] Such a method makes it possible to increase the safety of operations by stopping the autonomous cart before taking the load if this load does not correspond to that of the mission assigned to the cart.

[0019] Such a method increases operational safety by taking into account the actual dimensions of the load to be transported. The method thus allows the forklift's behavior to be adapted according to the loads being transported, thereby ensuring the safety of personnel.

[0020] The method thus makes it possible to verify the consistency between the task assigned to the forklift and the load actually present on the racking before carrying out the lifting and transport operations. The method therefore avoids relying solely on the information from the task assigned to the forklift to perform these operations.

[0021] According to a first embodiment, said camera is a 3D camera rendering a point cloud of coordinates measured in a frame associated with said 3D camera, and the determination step includes a digital processing step of said image obtained in the acquisition step which includes a substep of calculating the real value of said dimension of the load.

[0022] According to a second alternative embodiment, the determination step comprises a step of reading a barcode on said image obtained in the acquisition step, and a step of extracting the actual value of said load dimension from a table contained in a memory of the forklift based on the barcode read. For this alternative embodiment, said camera may or may not be a 3D camera.

[0023] According to the first embodiment, it is possible, for example, that:

[0024] - the load to be lifted and transported is annular,

[0025] - the task assigned to the reception stage includes theoretical values ​​of the depth and outer diameter of the annular load,

[0026] - the numerical processing step includes substeps for calculating the values actual depth and outer diameter of the annular load,

[0027] - the comparison step includes comparing the actual value and the value theoretical depth of the load, and comparison of the actual value and the theoretical value of the load's outer diameter,

[0028] - the carriage stopping step is performed if the difference between at least one of said values real and its theoretical value is greater in absolute value than a predefined limit value.

[0029] It is also possible to foresee, for example, that:

[0030] - the digital processing step of said image obtained in the acquisition step includes a substep of detecting a first inner circle located on a front face of the annular load and corresponding to the inner diameter of said annular load, and a second inner circle located on a rear face of the annular load and corresponding to an inner surface of said load,

[0031] - the calculation of the actual value of the depth of the annular load is carried out at starting from the diameter Di6 of the first inner circle, the diameter Dp of the second inner circle, and the distance d between said 3D camera and the front face of the load according to the following equation:

[0032] p=dx D^-Dr7 (Eq. 1 ) d,7

[0033] The "rear face" of the annular charge is understood to mean the front face of the charge that is oriented towards the side opposite the 3D camera. The "front face" of the annular charge is understood to mean the front face of the charge that is oriented towards the side of the 3D camera. The rear and front faces define the thickness of the charge.

[0034] According to one feature, the actual value of the depth of the annular charge is equal to the maximum deviation between the coordinates of the points of an inner surface of the annular charge contained between the inner circles, said deviation being measured along the axis of the frame oriented along the line of sight of said 3D camera.

[0035] According to another feature, the digital processing step of said image obtained in the acquisition step includes a substep of detecting a circle located on the front face of the annular charge and corresponding to the outer diameter of the annular charge.

[0036] For example, the acquisition step includes the following successive sub-steps:

[0037] - a first sub-step of acquiring at least one image;

[0038] - a sub-step of advancing the trolley towards the load over a predefined distance; and

[0039] - a second substep of acquiring at least one image carried out when the trolley has travelled said predefined distance, - and in which the substep of calculating the actual value of the outer diameter of the annular load is carried out from the image obtained in the first substep of acquisition, and the substep of calculating the actual value of the depth (P) of the annular load is carried out from the image obtained in the second substep of acquisition.

[0040] Advantageously, the digital processing step includes a substep for filtering the image obtained in the acquisition step, which is performed before any other substep of the digital processing step. This filtering substep reduces the amount of data to be processed by filtering the points of the images obtained in the acquisition step to retain only those points belonging to a region of particular interest. By limiting the calculations to the small areas of particular interest, the process accelerates the acquisition of results without degrading their quality. By limiting the data to the areas of interest, the required memory size of the control and digital image processing module associated with the 3D cameras is also reduced.

[0041] Preferably, the image acquisition step of the load is performed by a single 3D camera. Alternatively, the acquisition step can be performed by several 3D cameras. Alternatively, the acquisition step can be performed by one or more non-3D cameras capable of reading barcodes.

[0042] According to another aspect, the invention relates to an autonomous forklift comprising a vertically movable fork equipped with at least one arm, at least one 3D camera for acquiring at least one image of point cloud data, said 3D camera being fixed on the autonomous forklift by being centered with respect to the fork and having a viewing axis oriented forwards along a longitudinal axis of said forklift, a control and digital image processing module associated with the 3D camera, a wireless telecommunication device, as well as a control unit of said forklift configured for the execution of a method as described above.

[0043] Brief description of the figures

[0044] 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:

[0045] [Fig. 1] is a perspective view of an autonomous forklift according to an example of an embodiment of the invention;

[0046] [Fig.2] is a detail view of the forklift truck of [Fig. 1];

[0047] [Fig.3] schematically illustrates the forklift of [Fig.1] during its use;

[0048] [Fig.4] illustrates the flowchart of a method for lifting and transporting a load by a trolley from [Fig.1] according to an embodiment of the invention; and

[0049] [Fig.5] is a simplified example of an image acquired by a forklift camera in [Fig.1] in the case of an annular load. Detailed description of at least one embodiment

[0050] Figure 1 shows the main elements of an autonomous forklift truck 1 according to an embodiment of the invention.

[0051] The architecture of the 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 autonomous mode.

[0052] The self-contained forklift truck 1 illustrated in [Fig. 1] comprises a lifting member 2 including a platform 3 which supports a fork 4 comprising two arms 4a, 4b spaced laterally and extending towards the front of the truck. Alternatively, the fork 4 could comprise a single arm.

[0053] The apron 3 forms a frame. The apron 3 is provided with a horizontal upper cross member 3a, and two arms 3b, 3c extending vertically downwards from the upper cross member 3a.

[0054] The fork 4 also includes two uprights 4'a, 4'b which are fixed to the apron 3 and which each support one of the arms 4a, 4b. Each of the uprights 4'a, 4'b is fixed to one of the arms 3b, 3c of the apron.

[0055] 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 lift a pallet to be transported or another type of load and to place or grasp a pallet or other type of load at a height.

[0056] The fork 4 is capable of moving in translation in a vertical plane V defined by the carriage 3, along a vertical mast 5 of the trolley. The uprights 4'a, 4'b can slide along the mast 5. The fork arms 4a, 4b are movable between an extreme high position and an extreme low position, which is illustrated in [Fig. 1] and corresponds to a rolling position. In the extreme low position, the arms 4a, 4b are located at a distance from the ground.

[0057] The longitudinal axes of arms 4a, 4b are parallel. These longitudinal axes are oriented parallel to a horizontal axis X, and define a horizontal plane H called lifting plane. The arms 4a, 4b of the fork 4 are perpendicular to the vertical plane V. The arms 4a, 4b of the fork 4 are also preferably movable laterally relative to each other.

[0058] Alternatively, the arms 4a, 4b could also be telescopic or retractable, and / or angularly orientable around their longitudinal axis.

[0059] In a manner known per se, the trolley 1 is equipped with a drive system 6 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 of the trolley 1.

[0060] The trolley 1 is also equipped with an on-board location device 7, an on-board wireless telecommunication device 8 and an on-board control unit 9 ([Fig.3]) receiving information from the location device 7 and the wireless telecommunication device 8 to autonomously control the movement of the forklift.

[0061] The carriage 1 is also equipped with at least one 3D time-of-flight (TOF) camera 10 and an associated digital image control and processing module 11 ([Fig. 3]), called the vision module, which controls the image acquisition by the 3D camera and receives and interprets the images captured by the 3D camera. In the remainder of this description, module 11 will be referred to as the vision module.

[0062] In a manner known per se, the 3D camera 10 is capable of capturing an image of an object and reproducing a point cloud of relative coordinates measured with respect to a reference frame associated with the 3D camera. The reference frame associated with the 3D camera 10 comprises a coordinate system R composed of three orthogonal axes XI, Yl, Zl, as illustrated in [Fig. 2]. The Zl axis of the coordinate system is oriented here along the line of sight of the 3D camera 10, and the Y1 axis of the coordinate system is oriented along a horizontal axis Y perpendicular to the line of sight of the 3D camera 10. A 3D camera is capable of measuring distances along the three axes of its associated coordinate system. For example, as illustrated, the horizontal, vertical, or depth offset relative to the 3D camera 10 is measured along the Yl, XI, or Zl axes, respectively.

[0063] The 3D camera 10 is separate from the localization device 7. The 3D camera 10 is here separate from the vision module 11. Alternatively, the 3D camera 10 and the vision module 11 could form a single unit.

[0064] The control unit 9 includes the hardware and software means to control the operation of the drive system 6 according to the information received from the location device 7 and the telecommunications device 8.

[0065] The control unit 9 controls the operation of the drive system 6 also based on data from the vision module 11 and is configured to communicate with it. Alternatively, the vision module 11 could be integrated into the control unit 9. The control unit 9 also allows for the autonomous control of the lifting element 2.

[0066] As illustrated in Figures 1 and 2, the 3D camera 10 is centered with respect to the fork 4 and its viewing axis is oriented forward along a longitudinal axis of the carriage 1. The 3D camera 10 is fixed to the platform 3 at a constant height relative to the lifting plane H and without any possibility of relative movement with respect to said platform. The 3D camera 10 is movable in conjunction with the fork 4. The 3D camera 10 is here fixed to the lower part of the platform 3 above the lifting plane H. In variants not shown, the 3D camera 10 can be fixed to the platform 3 at the level of the lifting plane H or below this plane.

[0067] As will be described in more detail later, the 3D camera 10 is capable of capturing images of the environment located in front of the forklift 1, in order to determine the actual dimensions of the loads to be lifted and transported by the forklift.

[0068] The wireless telecommunications device 8 is configured to communicate with the control unit 9 and with a warehouse management system 18 (in English, “Warehouse Management System” or WMS) which is remote from the trolley 1 and intended to manage the operations of a storage warehouse and to control a fleet of trolleys 1.

[0069] Each trolley 1 receives, via the telecommunications device 8, instructions in the form of periodic digital messages issued by the WMS system 18 concerning its assigned tasks relating to movements to be carried out and loads to be transported. Each trolley 1 is capable of transmitting to the WMS system 18 digital messages representing the status of its assigned tasks. A trolley 1 can, for example, report an error encountered during the execution of a task by sending an error code.

[0070] We will now describe, with reference to [Fig. 4], a method 20 for verifying the safety of a load socket according to the invention. In the method to be described, the load is annular. An annular load generally comprises a support consisting of a hollow cylindrical core, usually provided with solid or radiating circular edges, intended to receive a wire or cable that winds around the core. Alternatively, an annular load may be a pneumatic device.

[0071] The process 20 begins with a preliminary receiving step 21 in which the wireless telecommunications device 8 of the trolley receives an instruction relating to a load to be transported and constituting a task assigned to the trolley 1 by the WMS system 18. The instruction includes information relating to the type of load to be transported, the dimensions of the load, the current position of the load and the des- destination of this.

[0072] In particular, regarding the dimensions of the annular load, the instruction received may, for example, include the theoretical value of the outer diameter, the theoretical value of the inner diameter, and / or the theoretical value of the depth. It is understood that ideally, the theoretical value of each dimension of a given load should correspond to the actual value of that dimension. However, it may happen that the theoretical value received does not correspond to the actual value of the load present in situ, which can lead to risks of accidents.

[0073] The information received, in particular information relating to the dimensions of the load to be transported, is stored in a memory of the trolley 1.

[0074] During the next movement step 22, 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 7 and the instruction received in the reception step 21.

[0075] The process 20 continues with an acquisition step 23 of at least one image of the load 12 by the 3D camera 10, which is controlled by the vision module 11. Image acquisition is performed at a predefined distance DI ([Fig. 3]) from the load 12. When the trolley is at this predefined distance D1, the control unit 9 stops the trolley 1 and sends an image acquisition request to the vision module 11, which commands the associated 3D camera 10 to capture images. The 3D camera 10 thus captures at least one image of the load 12 located in front of the trolley 1 and sends it back to the vision module 11. A simplified example of a captured image of a ring load is illustrated in [Fig. 5]. The images captured by the 3D camera 10 produce a point cloud with coordinates XI, Y1, ZI in the frame R associated with the 3D camera 10.

[0076] After acquisition step 23, the process continues with step 24 of determining the actual value of each dimension received with the instruction from the WMS system 18, that is, the actual value of each dimension for which the carriage received a theoretical value in reception step 21. The determination of the actual value is performed using at least one image obtained in acquisition step 23.

[0077] The determination step 24 includes a digital image processing step 25 of the images obtained, carried out by the vision module 11. It should be noted that the digital image processing can begin as soon as the image captured by the 3D camera 10 is made available to the vision module 11.

[0078] The digital processing step 25 includes a substep 25b of calculating the dimensions of the load 12 actually present on the shelving 13.

[0079] For example, the digital processing step includes a substep 25a of detecting circles 14, 16 located on a front face of the charge 12, and a circle 17 located on a rear face of the charge 12 ([Fig.5]).

[0080] The detection of the circles is carried out so that circle 14 is the circle perceived on the front face of the charge and which corresponds to the outer surface of the charge 12, and circles 16, 17 are respectively the circles perceived on its front face and on its rear face and corresponding to the inner surface of the charge 12. The detection of circles 14, 16 and 17 is carried out using known circle detection methods for example of the Hough transform type.

[0081] As previously stated, the numerical processing step includes a substep 25b of calculating the actual value of the dimensions of the load.

[0082] In this substep, the actual outer and inner diameters of the load are considered to be equal to the diameters Du, D6 ([Fig. 5]) of the outer circle 14 and inner circle 16 seen on the front face of the load. In this substep 25b, the diameter Dp of the inner circle 17 is also determined. The value of the diameter Dp is less than that of the diameter Di6 due to the vanishing angle of the image.

[0083] In this substep 35, the calculation of the actual value of the depth P of the load is carried out from the diameter values ​​Di6 and Dp of the circles 16, 17 determined in substep 25a of circle detection, and from the value of the distance d between the front face of the annular load and the 3D camera 10 which is determined by the latter, by applying the following equation:

[0084] p = dx W1 ) D)7

[0085] Alternatively, in another embodiment used for example when the contrast between the front and rear faces of the charge 12 is not sufficient, the actual value of the depth P of the annular charge is calculated as being equal to the maximum deviation between the coordinates of the points of the inner surface 15 of the annular charge 12, contained between the circles 16 and 17, said deviation being measured along the axis of the frame R oriented along the line of sight of the 3D camera 10.

[0086] After the determination of the actual values ​​of the load by the vision module 11, the control unit 9 has information relating to the dimensions of the load obtained by two separate channels, namely by the vision module 11 on the one hand and by the WMS system 18 on the other hand.

[0087] Referring again to [Fig.4], after the determination step 24, the process continues with a comparison step 26 of the actual values ​​determined during the determination step 24 and the theoretical values ​​of the dimensions of the load received in step 21.

[0088] In this case, in the described embodiment, the actual values ​​of the diameter The external, internal diameter, and depth of the load are compared to the corresponding theoretical values. Alternatively, it might be possible to determine one or two of these actual load values ​​for comparison purposes in step 26.

[0089] During the comparison step 26, if the difference between the actual value and the theoretical value of one of the dimensions of the load is greater in absolute value than a predefined associated limit value, the control unit 9 commands the trolley 1 to stop for reordering by an operator (step 27).

[0090] This limit value can be determined according to the permissible tolerances relating to the safety requirements of lifting and transport operations. The limit value can be specific to each dimension of the load considered.

[0091] During step 27 of stopping the trolley, the control unit 9 can transmit to the WMS system 18 an error message representative of the error encountered.

[0092] On the contrary, if the actual values ​​correspond to the theoretical values ​​associated up to the limit values, the trolley control unit controls the lifting and transport operation (step 28).

[0093] This lifting and transport operation can be carried out according to a predetermined lifting and transport scenario which is recorded in the control unit 9 of the forklift and which includes safety parameters specific to the theoretical dimensions of the load. For example, the safety parameters define in which aisles or openings of the warehouse the forklift can move depending on the dimensions of the load.

[0094] Alternatively, before piloting the lifting and transport operation, the control unit 9 can modify the safety parameters according to the actual dimensions of the load and then carry out the piloting according to the lifting and transport scenario with the adapted safety parameters.

[0095] In the implementation example just described, the acquisition step 23 of one or more images is carried out at the only distance DI from the load 12. Alternatively, the acquisition step 23 can include a first acquisition substep at the distance D1, followed by a second acquisition substep at a reduced distance D2 from the load, which therefore occurs after the carriage has advanced.

[0096] This two-step acquisition can be useful for large loads, particularly annular loads for which the viewing angle of the 3D camera 10 may be too narrow to capture both the inner and outer surfaces of the load. In this case, the first acquisition substep is performed in such a way as to calculate the actual values ​​of the outer and inner diameters of the load, and the second acquisition substep is performed from so that it is possible to calculate the actual value of the depth of the load 12.

[0097] In the illustrated embodiment, the digital processing step 25 includes a preliminary point filtering substep 25c. This substep 25c is performed before any other substep of the digital processing step 25 and reduces the amount of data to be processed by filtering the points of the images obtained in the acquisition step to retain only those points belonging to a region of particular interest. For example, the inner surface 15 of the ring charge 12 can constitute a region of particular interest ([Fig. 5]). By limiting the calculations to the small areas of the region of particular interest, the process accelerates obtaining the results without degrading their quality. By limiting the data to the regions of interest, the required memory size of the vision module 11 is also reduced. Alternatively, it is possible to omit this filtering substep 25c.

[0098] In the described implementation example, step 24 of determining the actual values ​​of the dimensions of the load is carried out by the digital processing 25 of the images obtained by the vision module 11.

[0099] In an alternative embodiment, the determination step 24 could include a step of reading a barcode on said image obtained in the acquisition step 23, followed by a step of extracting a real value of the or each dimension considered of the load from an array contained in the memory of the forklift as a function of the barcode read.

[0100] Furthermore, the implementation of the method has been described using an annular load. The invention remains within the scope of this description when the load is a palletized load. A "palletized load" is defined as a pallet supporting a load. A pallet is a platform that generally comprises a deck supported by struts or two decks connected by struts. A pallet may also be equipped with feet supporting the deck.

[0101] For a palletized load, the dimensions taken into consideration may be the height, depth and / or width of the load taken alone.

[0102] For example, the digital processing step may include a substep of detecting the front face of the load and a bottom face of the load using conventional computer vision algorithms. The width and height dimensions of the load are then calculated from the images of the front face, while the depth dimensions are calculated from the images of the bottom face.

Claims

Claims

1. Method (20) for lifting and transporting a load by an autonomous forklift truck comprising a vertically movable fork provided with at least one arm, said method being characterized in that it comprises: - a step (21) of receiving by the truck an assigned mission of moving the load to be lifted and transported which comprises a theoretical value of at least one dimension of said load; - a step (22) of moving the autonomous forklift truck in front of the load to be lifted and transported, - a step of acquiring (23) at least one image of the load by at least one camera fixed on the autonomous forklift truck while being centered relative to the fork and having a line of sight oriented forward along a longitudinal axis of said truck;- a step (24) of determining an actual value of said dimension of the load from said image obtained in the acquisition step (23), - a step (26) of comparing the actual value of said dimension of the load determined in the determination step (24) and the theoretical value of said dimension of the load received in the reception step (21), and - a step (27) of stopping the carriage if the difference between the actual value of said dimension and its theoretical value is greater in absolute value than a predefined limit value, or - a step (28) of lifting and transporting the load if the difference between the actual value of said dimension and its theoretical value is less than or equal in absolute value to the predefined limit value.;

2. Method according to claim 1, in which said camera is a 3D camera restoring a cloud of points of coordinates measured in a reference frame (R) associated with said 3D camera, and in which the determination step (24) comprises a step (25) of digital processing of said image obtained in the acquisition step (23) which comprises a sub-step (25b) of calculating the real value of said dimension of the load.

3. The method of claim 1, wherein the determining step (24) comprises a step of reading a barcode on said image obtained in the acquiring step (23), and a step of extracting the actual value of said load dimension from a table contained in a memory of the forklift based on the barcode read.

4. Method according to claim 2, in which: - the load to be lifted and transported is annular, - the mission assigned to the receiving step (21) comprises theoretical values of the depth (P) and the outer diameter of the annular load, - the digital processing step (25) comprises sub-steps (25b) of calculating the actual values of the depth (P) and the outer diameter of the annular load, - the comparison step (26) comprises the comparison of the actual value and the theoretical value of the depth of the load, and the comparison of the actual value and the theoretical value of the outer diameter of the load, - the step (27) of stopping the carriage is carried out if the difference between at least one of said actual values and its theoretical value is greater in absolute value than a predefined limit value.

5. Method according to claim 4, in which: - the step (25) of digitally processing said image obtained in the acquisition step comprises a sub-step (25a) of detecting a first inner circle (16) located on a front face of the annular load and corresponding to the inner diameter of said annular load, and a second inner circle (17) located on a rear face of the annular load and corresponding to an inner surface of said load, - the calculation of the real value of the depth (P) of the annular load is carried out from the diameter (Di6) of the first inner circle (16), the diameter (Dn) of the second inner circle (17), and the distance (d) between said 3D camera and the front face of the load according to the following equation: P^dx^- (Eq.D

6. Method according to claim 5, in which the actual value of the depth (P) of the annular charge is equal to the maximum deviation between the coordinates of the points of an interior surface of the annular charge included between the interior circles (16, 17), said deviation being measured along the axis of the reference frame (R) oriented along the line of sight of said 3D camera.

7. A method according to any one of claims 4 to 6, in wherein the step (24) of digital processing of said image obtained in the acquisition step comprises a sub-step (25a) of detecting a circle (14) located on the front face of the annular load and corresponding to the external diameter of the annular load.

8. Method according to any one of claims 4 to 7, in which the acquisition step (23) comprises the following successive sub-steps: - a first sub-step of acquiring at least one image; - a sub-step of advancing the carriage towards the load by a predefined distance; and a second sub-step of acquiring at least one image produced when the carriage has traveled said predefined distance, - and in which the sub-step of calculating the actual value of the external diameter of the annular load is carried out from the image obtained in the first acquisition sub-step, and the sub-step of calculating the actual value of the depth (P) of the annular load is carried out from the image obtained in the second acquisition sub-step.

9. Method according to any one of the preceding claims 2 or 4 to 8, in which the digital processing step (25) comprises a sub-step (25c) of filtering said image obtained in the acquisition step which is carried out before any other sub-step of the digital processing step (25).

10. Method according to any one of the preceding claims, in which the step of acquiring (23) said image of the load is carried out by a single 3D camera.

11. Autonomous forklift (1) comprising a vertically movable fork (4) provided with at least one arm, at least one 3D camera (10) for acquiring at least one image of point cloud data, said 3D camera being fixed to the autonomous forklift while being centered relative to the fork and having a line of sight oriented forward along a longitudinal axis of said carriage, a module (11) for control and digital processing of images associated with the 3D camera (10), a wireless telecommunications device (8), as well as a control unit (9) of said carriage configured for the execution of a method according to any one of claims 1 to 10.

Images