WO2019002918A1

WO2019002918A1 - Method and system for controlling and moving an automated guided vehicle (agv)

Info

Publication number: WO2019002918A1
Application number: PCT/IB2017/053925
Authority: WO
Inventors: Lepido Caselli
Original assignee: Simec S.R.L.
Priority date: 2017-06-29
Filing date: 2017-06-29
Publication date: 2019-01-03
Also published as: IT201700073088A1

Abstract

A method of controlling a vehicle (2) comprising the steps of a) providing motion-imparting (3) and transport (4) means for moving and transporting objects (O), b) providing sensor means (11) for detecting the position of the vehicle (2) and the movement of objects (O), c) providing a microprocessor unit (16) connected to the motion-imparting means (3) and the sensor means (11), d) installing a computer product containing an algorithm (18) and a file (19) containing an operating mission (M) defined by a path (R) having a trajectory (T) and moving steps (H) in the memory (17) of the unit (16), e) retrieving the file (19) by an operator to reproduce the mission (M) corresponding to the file (19), wherein the algorithm (18) comprises a self- learning mode for defining the file (19) by the steps of f) actuating the sensor means (11) and manually guiding the vehicle (2) by an operator for carrying out the mission (M), g) sampling the position and movement data along the trajectory (T), h) storing the sampled data to create the file (19) and i) interpolating the sampled data using a function for generating a reference path (R) as close as possible to the trajectory (T) for the mission (M) to be repeated in automatic mode by the vehicle (2) each time that it is retrieved by the operator.

Description

METHOD AND SYSTEM FOR CONTROLLING AND MOVING AN AUTOMATED GUIDED VEHICLE (AGV)

Field of the invention

[0001 ] The present invention generally finds application in the field of industrial and commercial transport and storage devices, and particularly relates to a method of controlling and moving at least one automated guided vehicle.

[0002] The invention also relates to a system for carrying out the above control method.

Background art

[0003] Methods and systems have been long known in the field of industrial and commercial plants for controlling and moving Automated

Guided Vehicles (AGV), which are adapted for transport and storage of objects of various types and sizes.

[0004] Namely, the vehicle is assigned an operating mission for moving at least one object and transporting it along a path in an industrial or commercial environment.

[0005] Generally, the system uses a central device having a microprocessor unit, which is adapted to continuously collect position data of each vehicle and compare it with previously stored environment map and object position data.

[0006] Furthermore, the central device continuously computes the most appropriate path for the vehicle and the trajectories required for moving the object to be transported according to the assigned operating mission.

[0007] Particularly, in the control method, as the mission is being carried out, the vehicle constantly communicates with the central device to update the state of the mission and its own position to determine the required instructions and avoid interference with any obstacles encountered in the path.

[0008] A first drawback of this known method is that the central device must store all the information concerning the objects to be moved and the environment in which it operates. [0009] This drawback is particularly felt if the information concerning the objects or the environment map must be manually updated which will make the definition of vehicle traffic rules particularly difficult.

[0010] A further drawback of this method is that the central device manages continuous reading/writing of data concerning the position and the operations carried out by each vehicle, which increases the computational cost of the microprocessor unit as vehicles are added.

[0011 ] In an attempt to at least partially obviate these drawbacks, methods and systems have been developed which allow a given vehicle to communicate with the central device and then share the received information with other vehicles.

[0012] US8639644 discloses a method of monitoring and managing a warehouse containing a plurality of objects and a central device containing the information of objects to be moved by a plurality of automated guided vehicles.

[0013] Particularly, the objects are equipped with labels containing indexes for addressing the information contained in the central device and susceptible of being read by the vehicles. The information relate the type, weight and size of the object, as well as the trajectories required for moving the object.

[0014] These vehicles are equipped with a plurality of sensors for reading labels and a microprocessor unit for calculating the path to be followed to reach the predetermined object.

[0015] The method also includes reading of object information by a first vehicle, following the movement trajectories and later sharing the information and trajectories with the other vehicles of the system.

[0016] A first drawback of this method is that the vehicle is required to connect to the central device to read object information and download object moving trajectory information.

[0017] Another drawback of this method is that the entire system requires an operator to constantly supervise the trajectories that are being followed by the vehicles to avoid inappropriate movements.

[0018] Yet another drawback of this method is that the system prevents the use of a learning function to learn the proper trajectories to be followed for object movement.

Technical Problem

[0019] In view of the prior art, the technical problem addressed by the present invention consists in greatly simplifying mission learning by vehicles and safely speeding up and simplifying object movement control.

Disclosure of the invention

[0020] The object of the present invention is to solve the aforementioned problem, by providing a method and a system for controlling and moving automated guided vehicles, that are highly efficient and relatively cost- effective.

[0021] A particular object of the present invention is to solve the aforementioned technical problem by providing a method and a system that allow any operator to simply and quickly define operating missions for the vehicle and to retrieve them in any operating situation.

[0022] A further object of the present invention is to provide a method and a system of the aforementioned type that afford high versatility regardless of the layout of the environment in which the vehicle operates.

[0023] Another object of the present invention is to provide a method and a system of the aforementioned type that reduce trajectory definition times.

[0024] Yet another object of the present invention is to provide a method and a system of the above mentioned type that can use commercially available motion and safety sensors.

[0025] A further object of the present invention is to provide a method and a system of the aforementioned type that allow an operator to manually define traffic rules for each vehicle.

[0026] Another object of the present invention is to provide a method and a system of the aforementioned type that eliminate the dead times associated with traffic congestion in the presence of fixed or moving obstacles.

[0027] A further object of the present invention is to provide a method and a system of the aforementioned type that considerably reduce the computational cost of the units contained therein. [0028] These and other objects, as more clearly explained hereinafter, are fulfilled by a method of controlling and moving at least one automated guided vehicle for moving and transporting objects in an industrial or commercial plant as defined in the independent claim 1 , which method comprises a step of providing an automated guided vehicle with motion-imparting and transport means for moving and transporting objects and a step of providing the vehicle with on-board sensor means for detecting vehicle position and object movement.

[0029] The method further comprises the provision of a microprocessor unit, operably connected to the motion-imparting means and the sensor means, on the vehicle, a step of installing a computer product, containing a control algorithm, and at least one file containing an operating mission defined by a path with a trajectory, in the memory of the microprocessor unit, and object moving steps as well as a step of retrieving the file by an operator to reproduce the mission corresponding to the file.

[0030] Particularly, the control algorithm comprises a self-learning mode for defining the file by a step of actuating the sensor means and manually guiding the vehicle by an operator to carry out the operating mission, a step of sampling the position and object movement data along the trajectory at regular intervals, a step of storing the sampled data to create the file and a step of interpolating the sampled data using an appropriate function to generate a reference path which is as close as possible to the trajectory, such that the mission may be repeated in automatic mode by the vehicle each time it is retrieved by the operator.

[0031 ] In a further aspect, the invention relates to a control system for an automated guided vehicle (AGV) as defined in claim 8.

[0032] Advantageous embodiments of the invention are obtained in accordance with the dependent claims.

Brief description of the drawings

[0033] Further features and advantages of the invention will be more apparent from the detailed description of a preferred, non-exclusive embodiment of a method and a system for controlling and moving at least one automated guided vehicle using a control algorithm comprising a learning mode according to the invention, which are described as a non- limiting example with the help of the annexed drawings, in which:

FIG. 1 is an exemplary perspective view of a vehicle of the invention;

FIG. 2 shows a diagrammatic view of the system of the invention;

FIG. 3 shows an exemplary plant for the system of Fig. 2;

FIG. 4 is a perspective view of a detail of the vehicle of Fig. 1 ;

FIG. 5 shows a diagrammatic view of the method of the invention;

FIG. 6 shows a diagrammatic view of a particular step of the method of Fig. 5.

Detailed description of a preferred exemplary embodiment

[0034] Particularly referring to the accompanying figures, a system is shown, which is generally designated by numeral 1 , for one or more automated guided vehicles, or AVGs, 2, 2', which are designed for moving or transporting objects O, such as mechanically manufactured items, castings, parcels, or palletized items.

[0035] The automated guided vehicle 2 is generally equipped with motion- imparting means 3 and transport means 4 for moving and transporting objects O, which are associated with respective motor means 5 for moving and transporting objects in an industrial or commercial plant P with stations for picking up and/or loading/unloading objects.

[0036] For example, the vehicle 2 may be a lift truck, a pallet truck or any wheel-mounted operating vehicle having a loading portion 7.

[0037] Namely, the vehicle 2 may be equipped with three-wheeled transport means 4 for transport operation in a plant P with narrow spaces, and may be four-wheeled 6 in case of heavier operation.

[0038] Furthermore, the vehicle 2 will be equipped with motion-imparting means 3 with transversely and laterally moving front lifting arms 8 having parallel forks made of a rigid metal material for the vehicle 2 to be able to quickly and safely move objects O.

[0039] Furthermore, the vehicle 2 may comprise a battery power source 9 installed in a protected internal compartment 1 0, e.g. in a rear position to balance the displacement of the center of gravity toward the motion-imparting means 3 when they are lifted.

[0040] Advantageously, as shown in FIGS. 1 and 2, the system 1 comprises sensor means 1 1 mounted on the vehicle 2 to detect its position along the path R as well as object moving steps H in the pick-up stations C and the loading/unloading stations L.

[0041 ] With these sensors 1 1 , the vehicle 2 will be able to navigate in a wholly autonomous manner in the plant P and along a predetermined path R using appropriate reference markers in predetermined positions of the plant, which are adapted to interact with the sensor means 1 1 on the vehicle 2 for triangulating the location of the latter.

[0042] The reference markers, not shown, will include a plurality of reflecting elements appropriately arranged in the plant P and adapted to reflect laser beams emitted from a 360 ° rotating head mounted on the vehicle 2.

[0043] In the exemplary embodiment of the figures, the rotating head 12 will be equipped with a laser scanner having a range of at least 1 50 m and an angular resolution of 0.5 ° which affords a navigation accuracy of the vehicle 2 with an error margin of about 3 cm.

[0044] Furthermore, the sensor means 1 1 may comprise an encoder 1 3 of absolute type which is mounted to motor means 5 to detect the motion of the movement means 3 and instantaneously control their speed and position.

[0045] Advantageously the sensor means 1 1 associated with the steering 14 of the vehicle 2 will afford total control of the steering angle by the operator and the encoder 1 3 associated therewith may ensure a positioning error of less than 0.5 °.

[0046] The motion-imparting means 3 for moving the objects O may be further associated with sensor means 1 1 for position control of the motor means 5 that can ensure an operator-adjustable positioning accuracy, in a range from 2 mm to 5 mm.

[0047] Conveniently, the automated guided vehicle 2 will comprise a modular system 1 5 for managing data D exchanged by the sensor means 1 1 and the inputs/outputs of the encoders 1 3 or the electronic devices, which are adapted to manage the motion control electronics for the vehicle 2.

[0048] As shown in FIG. 2, the sensor means 1 1 and the motor means 5 will be operably connected to a microprocessor unit 1 6 mounted to the vehicle 2 and having a memory in which a computer product containing a control algorithm 18 and a file 19 containing an operating mission M is installed.

[0049] Namely, the operating mission M on board the automated guided vehicle 2 is defined by a path R formed by a series of trajectories T that the vehicle 2 must follow to reach an object O and moving steps H for loading and unloading the object O.

[0050] As shown in the exemplary embodiment of FIG. 3, the path R followed by the vehicle 2 extends from a first base position B to a second pick-up position C in which an object O to be transported is located, and from a first moving step H' for the object O carried out by the motion-imparting means 3 for loading it.

[0051 ] The path R may further comprise a second series of trajectories T followed by the vehicle 2 from the second pick-up position C to a third final unloading position L in which the object O is unloaded through a second moving step H" for the object O.

[0052] This second moving step H" may comprise successive actuation of the motor means 5 to lift the motion-imparting means 3 and successive movements of the vehicle 2 toward the third unloading position K for safe unloading.

[0053] Furthermore, the path R may comprise an additional trajectory T of the vehicle 2 to reach a power supply station F which is located in a fixed location of the plant P, for charging the battery source 9 installed in the vehicle 2 for supplying power to the motor means 5 and the microprocessor unit 1 6.

[0054] Advantageously, the system 1 comprises control means 20 connected to the microprocessor unit 1 6 for access by an operator for selective actuation of the algorithm 1 8 and retrieval of the operating mission M.

[0055] These control means 20 may comprise a graphics interface 21 installed on the vehicle and designed for access by the operator, e.g. comprising a touch screen or a series of electromechanical buttons for selecting and defining the operating mission M.

[0056] In a preferred embodiment of the invention, the control means 20 may also comprise the selection of a particular operating mission M for reaching a given power supply station F.

[0057] In an alternative embodiment of the invention, the control means 20 may be also installed in a plurality of remote devices 22 and will comprise a wireless router 23 to connect the microprocessor unit 1 6 with the remote devices 22 and for connecting other automated guided vehicles 2' of the plant P, as shown in FIG. 2.

[0058] In a peculiar aspect of the invention, the control algorithm 18 comprises a self-learning mode for defining the file 1 9 of the operating mission M by actuation of the sensor means 1 1 and by sampling of the position and object movement data along the path R at regular intervals.

[0059] According to this peculiar aspect, the algorithm 1 8 is adapted to store the sampled data during manual guiding of the vehicle 2 by an operator that carries out the operating mission M.

[0060] Preferably the algorithm 1 8 comprises an interpolation function for interpolating the sampled data to generate a reference path R that is as close as possible to the trajectory T for the mission M to be repeated in automatic mode by the vehicle 2 each time it is retrieved by the operator.

[0061 ] Therefore, during the self-learning mode in which the operator manually guides the vehicle 2 along a trajectory T, the encoders 1 3 will record the state change data for the motor means 5 in the memory 1 7 of the microprocessor unit 15, whereas the rotating laser head 1 2 will record the instantaneous position of the vehicle 2 along the path R of the operating mission M.

[0062] The data recorded by the sensor means 1 1 will be saved in a file 19 and the control algorithm 18 may generate a reference path R for repeating the mission M by the interpolation function.

[0063] As shown in FIG. 4, the system 1 will comprise safety means 24 having a laser scanner 25 with a scan angle of about 270 °, which are installed on the vehicle 2 in a lateral position for automatic detection of any obstacles encountered during the operating mission M.

[0064] Laser scanners 25 may be configured with a range of 3 m and with 16 different control areas for direct selection during set-up.

[0065] While the vehicle 2 is manually guided during the self-learning mode, these safety means 24 may warn the operator of any movement error of the lifting arms 8 and allow the operator to stop the learning mode to correct the trajectory T using the control means 20.

[0066] Furthermore, the safety means 24 may comprise a plurality of light warning devices 26, which are designed to warn of any failures of the vehicle 2 or insufficient charge of the batteries.

[0067] These failures may be also indicated to the operator by the graphics interfaces 21 on the remote devices 22 to allow the operator to quickly take actions and stop the operating mission M, and bring the vehicle 2 back to a predetermined base position B.

[0068] In any case, the vehicle 2 may include manual safety means 24 of the emergency mushroom type 27, that can be actuated by the operator and can be reached from any side of the vehicle 2.

[0069] The system 1 may further include simultaneous use of different communication protocols for interfacing the microprocessor unit 16 with the various electromechanical devices of the system 1 , the navigation laser scanner 1 2 and the safety means 24, to avoid false measurements due to the presence of environmental noise or oscillations caused by the charge state of the battery 9,

[0070] These protocols may be of RS232, Ethernet, Ethercat, Modbus, WiFi, RS485, CAN bus types, as well as different types, according to the various proprietary protocols for the motor means 5. The data D exchanged through these communication protocols will be translated and managed by the modular management system 1 5. [0071 ] The invention further relates to a method of controlling and moving at least one automated guided vehicle 2, being part of the above described system 1 .

[0072] As schematically shown in FIG. 5, the method first comprises a step of a) providing motion-imparting 3 and transport 4means for moving and transporting objects O and a step of b) providing sensor means 1 1 for detecting the position of the vehicle 2 and the movement of objects O, on board the vehicle 2.

[0073] These steps are followed by a step of c) providing a microprocessor unit 1 6 operably connected to the motion-imparting means 3 and the sensor means 1 1 , and a step of d) installing a computer product containing an algorithm 1 8 and at least one file 19 containing an operating mission M defined by a path R having a trajectory T and moving steps H for the objects

O, in the memory 1 7 of the microprocessor unit 1 6.

[0074] A further step is provided of e) retrieving the at least one file 1 9 by an operator, to reproduce the operating mission M corresponding to said file

19.

[0075] In a peculiar aspect of the invention, the control algorithm 18 comprises a self-learning mode for defining the file 1 9, by means of a step of f) actuating the sensor means 1 1 and manually guiding the vehicle 2 by an operator to carry out the operating mission M, a step of g) sampling the position and movement data for the objects O at regular intervals along the trajectory T and a step of h) storing the sampled data to create the file 1 9.

[0076] Finally, the method includes a last step of i) interpolating the sampled data using an appropriate function, to generate a reference path R that is as close as possible to the trajectory T for the mission M to be repeated in automatic mode by the vehicle 2 each time it is retrieved by the operator.

[0077] Namely, the function for generating the reference path R may comprise a graphical interpolation using fifth order Bezier curves, as shown in FIG. 6.

[0078] This type of interpolation is known to define a differential curve which follows the behavior of a given traverse and is obtained by recursive or direct computation methods. Therefore, the reference path R of the operating mission M will be defined as the result of the differential curve that follows the behavior of the trajectory T obtained by manually guiding the vehicle 2 by the operator.

[0079] As shown in FIG. 3, the operating mission M may comprise a variable-geometry path R comprising straight and curvilinear sections and moving steps H for the objects O carried out by the motion-imparting means 3 for loading/unloading, installed in the vehicle 2.

[0080] Furthermore, the path R may comprise a trajectory T designed to avoid a fixed or movable obstacle within the plant P.

[0081 ] The step of f) actuating the sensor means 1 1 and the self-learning mode and the step of e) retrieving the file 1 9 may be carried out by an operator through the graphics interface 21 installed on the vehicle 2 or through a graphics interface 21 installed on a remote computer 22.

[0082] In a non-limiting embodiment of the invention, the method includes, after the step of h) storing the sampled data, a later step of j) transmitting the operating mission M to another automated guided vehicle 2' of the plant P.

[0083] This transmission step j) can reduce the self-learning time for the vehicles 2, 2' in the plant P, thereby reducing the operating time and the operating costs of the plant P.

[0084] The above disclosure clearly shows that the method and system of the invention fulfill the intended objects and particularly can greatly simplify mission learning by an automated guided vehicle, and afford quick, simple and safe object moving control.

[0085] The method and system of the invention are susceptible to a number of changes or variants, within the inventive concept disclosed in the appended claims.

[0086] While the method and system have been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner. Industrial applicability

[0087] The present invention may find application in industry, because it can be produced on an industrial scale in factories operating in the field of industrial and commercial transport and storage devices.

Claims

A method of controlling and moving at least one automated guided vehicle (2) for moving and transporting objects (O) in an industrial or commercial plant (P), said method comprising the steps of:

a) providing an automated guided vehicle (2) with motion- imparting means (3) and transport means (4) for moving and transporting objects (O);

b) providing the vehicle (2) with sensor means (1 1 ) for detecting the position of said vehicle (1 ) and the movement of objects (O);

c) providing said vehicle (2) with a microprocessor unit (16) operably connected to said motion-imparting means (3) and said sensor means (1 1 );

d) installing a computer product containing a control algorithm (18) and at least one file (19) containing an operating mission (M) defined by a path (R) having at least one trajectory (T) and moving steps (H) for the objects (O) in the memory (17) of said microprocessor unit (16);

e) retrieving said at least one file (19) by an operator to reproduce the operating mission (M) corresponding to said file (19);

wherein said control algorithm (18) comprises a self-learning mode for defining said file (19) by the following steps:

f) activating said sensor means (1 1 ) and manually guiding the vehicle (2) by an operator for carrying out said mission (M); g) sampling the position and movement data for the objects (O) along said trajectory (T) at regular intervals;

h) storing the sampled data to create said file (19);

i) interpolating the sampled data using a predetermined function for generating a reference path (R) as close as possible to the trajectory (T) for said mission (M) to be repeated in automatic mode by the vehicle (2) each time that it is retrieved by the operator.

A method as claimed in claim 1 , characterized in that said step of f) activation of said sensor means (1 1 ) and said self-learning mode is carried out by the operator through a graphics interface (21 ) installed on said vehicle (2).

A method as claimed in claim 1 , characterized in that said sampling step g) is carried out along said trajectory (T) at points spaced at a distance that can be appropriately adjusted by an operator in a range from 5 cm o 30 cm, and is preferably close to 20 cm.

A method as claimed in claim 1 , characterized in that said operating mission (M) comprises a variable-geometry path (R) with straight and curvilinear trajectories (T), as well as steps for moving (H) the objects (O) by said motion-imparting means (3) installed in said vehicle (2). A method as claimed in claim 1 , characterized in that said function for generating a reference path (R) comprises a graphical interpolation using fifth-order Bezier curves.

A method as claimed in claim 1 , characterized in that said path (R) comprises a trajectory (T) that is designed to avoid a fixed or movable obstacle within the plant (P).

A method as claimed in one or more of the preceding claims, characterized in that, after said step of h) storing the sampled data, a step is provided of j) transmitting said operating mission (M) to another automated guided vehicle (2') of said plant (P).

A system (1 ) for controlling an automated guided vehicle (2) designed to transport, move and/or store objects (O) in an industrial or commercial plant (P), by carrying out the method as claimed in claims 1 to 7, comprising:

- an automated guided vehicle (2) having motion-imparting (3) and transport (4) means for moving and transporting objects (O) associated with respective motor means (5);

- sensor means (1 1 ) mounted to said vehicle (2) to detect the position thereof along a trajectory (T) and the moving steps (H) for the objects (O) in the pick-up (C) and loading/unloading (L) stations;

- a microprocessor unit (1 6) operably connected to said motor means (5) and said sensor means (1 1 );

- a computer product installed in the memory (1 7) of said microprocessor unit (16) containing a control algorithm (1 8) and a file (1 9) containing an operating mission (M) defined by a path (R) composed of said at least one trajectory (T) and said moving steps (H);

- control means (20) connected to said microprocessor unit (1 6) accessible by an operator for selective actuation of said algorithm (1 8) and retrieval of said operating mission (M);

wherein said control algorithm (1 8) comprises a self-learning mode for defining said file (1 9) by actuation of said sensor means (1 1 ) and by sampling of the position and movement data for the objects (O) along said trajectory (T);

wherein said algorithm (18) is adapted to store the sampled data during manual guiding of the vehicle (2) by an operator that carries out said operating mission (M);

wherein said control algorithm (1 8) comprises an interpolation function for interpolating the sampled data to generate a reference path (R) that is as close as possible to said trajectory (T) for said mission (M) to be repeated in automatic mode by the vehicle (2) each time it is retrieved by the operator.

9. A system as claimed in claim 8, characterized in that it comprises reference markers arranged in predetermined positions of the plant (P) and adapted to interact with said sensor means (1 1 ) installed on the vehicle (2) for triangulation of its location along the path (R) of said operating mission (M), wherein said reference markers comprise a plurality of reflective elements which are adapted to reflect laser beams emitted from a 360 " rotating head (1 2) mounted on said vehicle (2).

10. A system as claimed in claim 8, characterized in that it comprises safety means (24) having a laser scanner (25) with a scan angle of about 270 °, which are installed in said vehicle (2) for automatic detection of any obstacles encountered during said operating mission (M).

1 1 . A system as claimed in claim 8, characterized in that it comprises a battery power source (9) installed in said vehicle (2) for supplying power to said motor means (5) and said microprocessor unit (1 6), said battery source (9) being adapted to be charged by a power supply station (F) situated in a fixed location in said plant (P).

1 2. A system as claimed in claim 8, characterized in that said sensor means (1 1 ) comprise an encoder (1 3) installed on said motor means (5) for detecting the motion of said motion-imparting means (3) during said self-learning mode.

1 3. A system as claimed in claim 8, characterized in that said control means (20) comprise a graphics interface (21 ) installed on said vehicle (2) for access by the operator and a wireless router (23) for connecting said microprocessor unit (1 6) with a plurality of remote devices (22) and for connecting together other automated guided vehicles (2') that are part of said plant (P).