Method and device for controlling a floor conveyor system

Abstract

The present invention comprises a method for controlling a floor conveyor device for conveying a loaded or unloaded load carrier (16), having two controllable conveying units (12a, 12b) which can be moved independently of one another, wherein each conveying unit (12a, 12b) comprises: - a chassis, - at least one drive system (30) which drives at least one floor roller of the conveying unit (12a, 12b), - at least one carrying element (18) for supporting the load carrier (16), - a control system (1), and - a sensor system (25; 40-43) for detecting environmental parameters, which sensor system is coupled or connected to the control system (1), wherein each conveying unit (12a, 12b) can be moved relative to the respective other conveying unit (12a, 12b) and independently of the respective other conveying unit (12a, 12b) along any desired direction of travel, and the conveying units (12a, 12b) can interact in order to convey a load carrier (16), wherein the conveying units (12a, 12b) are coupled to one another in control terms in order to carry out synchronized movements, wherein a control system (1a) of the first conveying unit (12a) controls the first conveying unit (12a) and the second conveying unit (12b) so that both conveying units (12a, 12b) can carry out synchronized movements, wherein the control system (1b) of the second conveying unit (12b) takes over the control of the first conveying unit (12a) and the control of the second conveying unit (12b) if the sensor system (25; 42, 43) of the second conveying unit (12b) reports safety-relevant information and / or detects damage to a safety protection zone and / or if there is an emergency stop signal at the second conveying unit (12b).

Description

[0001] Attorney file: P102372WOXX Applicant: FILICS GmbH

[0002] Method and device for controlling a floor conveyor system

[0003] The invention relates to a conveying device for conveying loaded and unloaded load carriers. The conveying device comprises a first conveying unit (or skid) and a second conveying unit (or skid), wherein both conveying units can move independently of each other and are preferably identical in construction.

[0004] The first and second conveying units can move autonomously at any time, either independently or together as a conveying system, for example within a hall. Two conveying units constitute a conveying system. A conveying system is designed to move underneath load carriers, especially pallets, lift them using a lifting / lowering unit, convey them to a location while lifted, and then lower them again. Each conveying unit can be dimensioned to fit under the clearance profile of the load carriers. A conveying system is known, for example, from DE 10 2007 046 868 A1.

[0005] German patent application DE 10 2008 014 877 A discloses an exemplary embodiment of a conveying device, whereby this system enables the automatic loading of pallets into trucks. For this purpose, two transport trolleys form a transport trolley pair, which can drive under the pallets, lift them, and convey them. Such a conveying unit is equipped with an electrical supply cable, which can also be used as a pull rope to make trajectory corrections.

[0006] A wireless conveyor system is essential for unrestricted flexibility. This requires integrating all necessary components of the conveyor unit—a control unit, at least one lifting / lowering unit, a power supply, and at least one drive unit consisting of at least one driven wheel—into each unit. Therefore, a highly integrated design is necessary.

[0007] For such a conveyor system, a warning function, such as a collision warning system, is required to operate in open or unfenced areas, for example, in the vicinity of people. One option for collision warning is the use of detection devices. Without such a device, applications such as those in production or logistics facilities without enclosed building boundaries are unsafe. It is particularly advantageous if the collision warning system is designed for any direction of travel, thus allowing the full flexibility of the conveyor system, such as lateral movement, to be utilized. Furthermore, a ground-level collision warning system should be highly robust. Additionally, orientation within the surroundings is desirable for the flexible conveyor unit. Various guidance systems can be implemented for this purpose.For example, floor markings can be used for the conveyor unit to travel along. However, these severely limit the system's flexibility.

[0008] From DE 10 2015 010 718 Al a radar-based, direction-bound detection device for conveying units of a conveying system is known.

[0009] EP 3 924 291 Bl discloses a conveying device for conveying loaded or unloaded load carriers, comprising a first conveying unit and a second conveying unit, each conveying unit consisting of a chassis, at least one support element for supporting the load carrier, at least one lifting / lowering unit for raising and lowering the support element, a sensor system for detecting environmental parameters, and at least one drive system which drives at least one bottom roller of the conveying unit, and each conveying unit being movable relative to the other conveying unit and independently of the other conveying unit along any direction of travel, wherein the environment of the conveying device can be detected in the raised state with a detection plane below the load carrier by means of the arrangement of the sensor system in both conveying units, and in the unraveled state the detection plane intersects the load carrier.

[0010] One of the aims of the invention is to make a conveying device safer.

[0011] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are defined in the dependent claims. A material handling device for conveying a loaded or unloaded load carrier consists of at least two independently movable, controllable conveying units or skids, each conveying unit comprising a chassis, at least one drive system which drives at least one base roller of the conveying unit, at least one support element for supporting the load carrier, a control system, and a sensor system for detecting environmental parameters. The support element can be raised or lowered by a lifting / lowering unit, for example, by moving it vertically to the floor.

[0012] Each conveying unit can move relative to and independently of the other conveying units along any direction of travel, and the conveying units can work together to convey a load carrier. For this purpose, the conveying units can be coupled to each other via control systems to execute synchronized movements, whereby a control system of one, for example, the first conveying unit, can control both that first and the second conveying unit, so that both conveying units can execute synchronized movements controlled by the control system of the first conveying unit.

[0013] According to a first aspect of the invention, the control system of the controlled, i.e., second, conveying unit can take over the overall control, i.e., the control of the first conveying unit and the control of the second conveying unit, if the sensor system of the second conveying unit reports safety-relevant information and / or detects a violation of a safety protection field and / or an emergency stop signal is present at the second conveying unit.

[0014] Safety-relevant information or signals are preferably prioritized or processed with priority by the control system receiving these signals.

[0015] A first conveying unit, as defined in this description, is the unit that initially assumes overall control of the material handling system. This means it has a control system that manages the movement of this first conveying unit and the movement of one or more additional conveying units, such as a second conveying unit. This second unit might be wirelessly connected to the first conveying unit and receive control signals from it or its control unit. A second conveying unit is the unit controlled by the first conveying unit. Typically, both conveying units have an identical design.If the second conveyor unit, or its control system, takes over overall control of the conveyor units—for example, if a safety-relevant signal is detected by a sensor in the second conveyor unit—the roles between the first and second conveyor units are reversed. The previously controlled conveyor unit becomes the controlling conveyor unit, and vice versa. Advantageously, the control signals intended to transfer overall control are processed with priority.

[0016] This eliminates the need to first transfer safety-relevant data from the controlled conveyor unit to the controlling conveyor unit when, for example, an obstacle is detected by the controlled conveyor unit, in order to receive a control signal (back) from the controlling conveyor unit, which would then react to this signal. This would lead to an unnecessary delay. Instead, for example, a control system already present in the controlled conveyor unit, which previously did not have the (master) control function, can take over overall control in order to react immediately to a safety-relevant signal. This control unit then acts as the new master and assumes overall control, which can be communicated to the previous master control unit, thus reversing the roles between the master and slave conveyor units.Of course, it is also possible that if a safety-relevant signal is detected again by the previously controlled master (now slave) conveyor unit, it will resume the master function. For example, the material handling system will always be controlled as the master by the conveyor unit that detected the last safety-relevant signal.

[0017] A control unit of a conveyor unit (or skid) handles the overall control of the conveyor units (for example, a two-skid system). This control unit thus acts as the master and controls the movement of its own (first) conveyor unit as well as the (second) conveyor unit, which may be connected or coupled to it via a data link, such as a radio connection. Control signals are transmitted unidirectionally, for example, only from the first conveyor unit to the second. There is no direct mechanical coupling between the two conveyor units, but an indirect connection may exist, for example, when a load carrier is lifted together. Generally, each control unit can receive control signals or information from a higher-level control computer, which it then translates into specific movements of the conveyor unit(s).

[0018] Such a master-slave structure is a hierarchical (drive) control of two or more conveying units by a master or a master conveying unit, which in addition to the master conveying unit can also control one or more slave conveying units, such as one or more subsequent industrial trucks.

[0019] According to the invention, the slave conveyor unit can take over overall control when safety-relevant information is available at the slave conveyor unit. Safety-relevant information can be, for example, an emergency stop signal. Such an emergency stop signal can be generated, for example, by actuating an emergency stop switch on the conveyor unit or by detecting an obstacle in the direction of movement, depending, for example, on direction, distance, and speed. Safety-relevant information can also be, for example, the violation of a predefined protective field, if, for example, a person moves into a planned movement area of ​​the conveyor unit(s) or an obstacle is detected within a predefined area of ​​the conveyor unit or the load carrier that can be detected by one or more sensors.

[0020] In this case, the controlled slave conveyor unit has the ability to actively intervene in the control system and is given priority by the previous master conveyor unit, thus becoming the new master conveyor unit. The master conveyor unit and slave conveyor unit therefore exchange roles (master-slave reverse system).

[0021] The control system of the first conveying unit can receive data from the sensor system of the first conveying unit, for example via internal wiring within the first conveying unit or via a radio connection. According to a second aspect of the invention, which is independent of the first aspect of the invention or can be combined with it, it can also receive data from the sensor system of the second conveying unit, for example via wireless transmission or a radio connection. This makes it possible for the control system of a conveying unit, which controls all two (or more) conveying units, to access sensor signals or sensors that are not directly located on or in the controlling conveying unit.The field of view of the entire system, i.e. the material handling equipment consisting of the individual conveying units, can thus be extended by accessing the sensors which are arranged on the controlled conveying units.

[0022] Sensor signals or WAM information can be shared, i.e., exchanged bidirectionally between the conveyor units (or even just transmitted from the slave to the master), so that the master can also use information from the controlled conveyor unit (slave) to control both conveyor units (client-server architecture). This expands the master's available field of view, as it can access not only the sensors of its own master conveyor unit but also those of the slave conveyor unit. This is particularly advantageous when moving sideways towards the slave conveyor unit, since the master conveyor unit's sensors' view is obstructed by the slave unit.

[0023] This allows information to be captured or obstacles to be detected that are not only within the field of view of the sensors of the master conveyor unit (i.e., visible from the master conveyor unit), but also information that is only within the field of view of the controlled conveyor unit or also within the field of view of other material handling equipment. This is the case, for example, when the material handling equipment is moving sideways towards the controlled (slave) conveyor unit or when the material handling equipment is following behind a preceding material handling equipment. This would not be possible without linking the sensors in the controlled conveyor unit or other conveyor units with the control system in the controlling conveyor unit.

[0024] The classic master-slave configuration is thus extended to include the sharing of sensor and safety data, allowing the master controller to access sensor signals or safety-relevant information from all controlled conveying units, or to receive this data wirelessly from the controlled conveying unit(s). The master-slave configuration can be maintained, or, if safety-relevant information is available on the slave side (controlled conveying unit), it can be reversed, as described above. It is also possible for the control system of a material handling system to not only access the sensor signals of, for example, the two conveying units belonging to that system, but also to be coupled with sensors from other, for example, neighboring, conveying systems or units, in order to access their sensor signals as well.This allows, for example, safety-relevant information for the relevant industrial truck to be determined or a violation of a safety protection field to be detected, even if this information is not directly within the field of view of the industrial truck's sensors, such as an obstacle that lies on a planned route of this industrial truck but cannot yet be seen or detected by a sensor of this industrial truck because this obstacle is behind a corner around which a neighboring industrial truck is located and can detect this obstacle with its own sensors.

[0025] The sensors of the sensor system can be optical sensors or laser scanners, which are preferably arranged on a front and a rear side of each conveying unit, for example to enable a 360° view or a 360° scan of the (immediate) surroundings of the conveying unit.

[0026] Each conveyor unit can be equipped with a chassis sensor, which is coupled or connected to the control system and detects whether a floor roller is blocked or spinning freely. A blocked floor roller can lead to deviations in the conveyor's behavior and thus to mispositioning of the conveyor unit and consequently the load carrier. Similarly, a spinning floor roller, i.e., a floor roller that does not translate the drive rotation into a corresponding movement of the conveyor unit, can lead to deviations in the conveyor's behavior and thus to mispositioning of the conveyor unit and consequently the load carrier. The signals from the chassis sensor can be transmitted to the conveyor unit's control system as safety-relevant information.

[0027] Each conveying unit can be equipped with a lifting mechanism sensor that detects whether the lifting mechanism is functioning correctly, for example, whether it is blocked or is not correctly executing predefined lifting or lowering commands. In the event of a malfunction being detected, this can be transmitted as a safety-relevant signal to the control unit, which can then initiate an emergency stop of the entire material handling system, i.e., the affected conveying unit and any other conveying unit coupled to it.

[0028] In each conveyor unit, an emergency stop switch can be coupled or connected to the control system as a sensor and, for example, transmit a stop signal to the control system when the emergency stop switch is activated or pressed. This can happen, for example, by a user, or if the conveyor unit with the emergency stop switch encounters an obstacle.

[0029] An optional deadman's switch can monitor whether the communication link between the conveyor units is intact. If not, for example, immediately upon a data connection failure or only after a data signal has not been received from the other conveyor unit for a period exceeding a predefined time (e.g., 1 second or 100 milliseconds), it triggers a signal or a switching action, such as an emergency stop of the conveyor units. The deadman's switch can be integrated into each individual conveyor unit. Since the deadman's switch is preferably present in both conveyor units, they will stop simultaneously in the event of an emergency stop triggered by the deadman's switch, thus preventing safety-critical situations (one conveyor unit braking while the other continues moving).

[0030] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments and with reference to the drawings. The drawings show:

[0031] Figure 1 shows a perspective view of a first embodiment of a conveying device, which is shown before entering a load carrier;

[0032] Figure 2 shows a schematic top view of a conveying unit of the conveying device of the first embodiment;

[0033] Figure 3 shows another view of the embodiment shown in Figure 2;

[0034] Figure 4 shows a schematic side view of the conveying unit in the unlifted state with a detection plane;

[0035] Figure 5 shows a schematic side view of the conveying unit in the raised position with a detection plane; Figure 6 shows a schematic side view of the conveying unit below a

[0036] load carrier, which is in the unlifted state;

[0037] Figure 7 is a schematic side view of the conveying unit below a

[0038] load carrier, which is in the raised state;

[0039] Figure 8 is a schematic top view of the first embodiment of the

[0040] Conveyor system with a load carrier; and

[0041] Figure 9 shows a schematic diagram of a material handling system.

[0042] Fig. 1 shows a conveying device 10 consisting of two independent conveying units 12a and 12b, which can be identical in construction. Both conveying units 12 travel under the open space 24 of the load carrier 16, which in this case is represented in the form of a pallet. Each conveying unit 12 of the conveying device 10 can lift the load carrier 16 by means of a lifting / lowering device and move the load carrier 16 in the lifted state to a destination.

[0043] The lifting / lowering unit (not shown) is designed for raising and lowering a support element and can operate independently of the drive system of the respective conveyor unit 12. The support element could have a U-profile, T-profile, or L-profile cross-section.

[0044] The drive system (not shown) consists of at least one drive module, which freely and independently drives at least one floor roller of the respective conveyor unit. The drive system and / or each drive module can advantageously also include a steering unit by means of which a steering movement of the respective conveyor unit can be controlled. The corresponding control commands come from a control system 1 of the conveyor device.

[0045] At least two conveying units 12 form a conveying facility 10, whereby any two conveying units can synchronize to form a conveying facility.

[0046] Each conveying unit 12 can move freely and independently of the other conveying units 12. Thus, each conveying unit 12 can move independently and, when a conveying order is received, synchronize itself at any point with any other conveying unit of a conveying system to form a conveying device 10. Fig. 2 shows the conveying unit 12 schematically from above. In the illustrated embodiment, a conveying unit 12 has at least two sensor units 40 and 41, which together form a sensor system 25. The respective detection ranges of the sensor units 40, 41 are shown in Fig. 2 and are designated by the ranges 40a and 41a. The superimposed ranges are detected by both sensor units 40 and 41. Furthermore, the drive system 30 is shown, which in the illustrated embodiment consists of four individual drive units 51, 52, 53, 54.In a preferred design, each of these drive units comprises a floor roller which is freely rotatable about a vertical axis. The vertical axis is preferably the vertical center axis of the respective drive unit 51, 52, 53, 54.

[0047] Fig. 3 shows the sensor units 40, 41 of the sensor system 25 within the conveyor unit 12, where the longitudinal axis 22 of the conveyor unit 12 is also shown. The minimum detection angle α is indicated, measured from the longitudinal axis 22. This minimum detection angle α is preferably greater than 5°. Likewise, the

[0048] The solid angle detection range β of each sensor unit 40, 41 is shown, which in the illustrated embodiment is approximately 260°. The sensor units 40, 41 can be designed as optical sensor units 40, 41, in particular as laser scanners 40, 41.

[0049] Fig. 4 shows the conveying unit 12 in a side view in the unlifted state. The distance between the detection plane d, which in the illustrated embodiment runs parallel to the floor 21, should be less than 20 cm. The support element 18 can be moved vertically to the floor 21 by means of the lifting / lowering unit (not shown). Two drive units 17 of a drive system 30 are also shown in Fig. 4 by way of example.

[0050] Fig. 5 shows the conveying unit 12 in a side view in the raised position. In the illustrated embodiment, the support element 18 is located above the detection plane 19.

[0051] Fig. 6 shows a schematic side view of the conveying unit 12 in its unlifted state. The detection line 19 of the sensor units 40, 41 can be angled by an angle y up to 5° relative to a horizontal plane. In the illustrated embodiment, the angle is 0°. The detection plane 19 is therefore parallel to the base 21. In an advantageous embodiment, the detection line 19 intersects the load carrier 16 in its unlifted state.

[0052] Fig. 7 shows a schematic side view of the conveying unit 12 in the raised position. In this state, unlike in Fig. 6, the detection plane 19 no longer intersects the load carrier. The distance h between the upper edge of the load carrier 16 and the detection plane 19 should be greater than 10 cm. It is conceivable that, in an advantageous embodiment, the sensor units 40, 41 are attached to vertically stationary components, for example, the chassis.

[0053] Fig. 8 shows a top view of a conveyor 10 with load carriers 16. In the illustrated embodiment, the conveyor 10 is equipped with two sensor systems 25, namely one sensor system 25 per conveyor unit 12, each with two sensor units 40, 41 and 42, 43. These sensor units detect the environment in the indicated detection areas 40a-43a. By combining the individual detection areas 40a-43a, it is possible to detect the environment in its entirety, i.e., over a total detection area of ​​360°.

[0054] Fig. 9 schematically shows a material handling device consisting of a first conveying unit 12a and a second conveying unit 12b. The suffixes "a" and "b" merely indicate that the respective component belongs to the first conveying unit 12a or the second conveying unit 12b, respectively. The components themselves are identical in construction.

[0055] One of the two conveying units, in the following example the first conveying unit 12a, forms the controlling conveying unit, which controls the entire material handling system consisting of both conveying units 12a and 12b. The second conveying unit 12b is therefore the (currently) controlled conveying unit.

[0056] Each conveyor unit 12 has a control system 1 that receives data from all sensors and transmits control signals to the drive units 17. An emergency stop switch 3 is located at each front and rear end of a conveyor unit 12 and can also be considered a sensor. An optical sensor unit 40, 41, 42, 43 is located at each front and rear end of a conveyor unit 12. Likewise, a chassis sensor 2 is provided at each front and rear end of a conveyor unit 12. The control system 1 is connected to a communication unit 4, which can establish a wireless data connection 6 to another conveyor unit 12.

[0057] As described above, the control system la of the controlling conveying unit 12a can handle the overall control, i.e., the control of the first conveying unit 12a itself and the control of the second conveying unit 12b. The control signals from control system la are transmitted within the controlling conveying unit 12a, for example, via cable to the front and rear drive units 17a. The control signals for the controlled conveying unit 12b are transmitted from control system la to communication unit 4a. Communication unit 4a is in (wireless) data communication 6 with communication unit 4b of the controlled conveying unit 12b. From communication unit 4b, the corresponding control signals are transmitted to the connected control system 1b, from where the front and rear drive units 17b are controlled.This allows a synchronized movement of the two conveyor units 12a and 12b to be achieved, controlled by only one (master) control unit la. The control signals or drive signals can be identical, as for example during straight-line travel, or they can differ, for example, due to the different curve radii (inner radius of one conveyor unit and outer radius of the other) during cornering, in order to ensure the required synchronization when transporting a load carrier 16.

[0058] If, for example, the optical sensor 42 of the sensor system of the second controlled conveyor unit 12b reports safety-relevant information, because it detects, for instance, a violation of a safety protection field (in Figure 9, for example, to the right of conveyor unit 12b), or if an emergency stop signal is present at the second conveyor unit 12b, the second conveyor unit 12b, or rather its control system 1b, can take over the overall control of conveyor units 12a and 12b. The roles between the first and second conveyor units are thus reversed. The previously controlled conveyor unit 12b becomes the controlling conveyor unit, and the previously controlling conveyor unit 12a becomes the controlled conveyor unit in this case.

[0059] As an immediate reaction, for example, the newly controlled conveyor unit 12b can initiate braking, an evasive maneuver, or an emergency stop and transmit these control signals not only to its own drive unit 17b, but also, via radio link 6 and control unit 1a, to the drive system 17a of the coupled conveyor unit 12a, in order to perform a synchronized braking, synchronized evasive maneuver, or synchronized emergency stop. The controlled (slave) system, i.e., the controlled conveyor unit 12b, thus has the ability to actively intervene in the control process.

[0060] According to another embodiment, the controlling (master) conveying unit 12a can retain overall control of the conveying device 10 if a safety-relevant signal is present at the controlled conveying unit 12b or is detected by its sensors, such as the optical sensors 42 or 43. In this case, only the sensor signal, or the sensor signal evaluated by the control unit 1b, or a safety-relevant signal is transmitted from the conveying unit 12b to the control unit 1a of the conveying unit 12a, which controls the synchronized overall response of both conveying units 12a and 12b and transmits the corresponding control signal to its own drive unit 17a and via the data connection 6 to the drive unit 17b.

[0061] Reference sign list la Tax system of the first funding institution

[0062] 1b Tax system of the second funding institution

[0063] 2 chassis sensor

[0064] 3 emergency stop switches

[0065] 4 Communication unit

[0066] 5 Emergency braking or emergency stop device

[0067] 6. Data connection, radio connection

[0068] 10 F conveyor system

[0069] 12 conveying units

[0070] 12a first delivery unit

[0071] 12b second support unit

[0072] 16 load carriers

[0073] 17 Drive unit

[0074] 18 Supporting element

[0075] 19 Detection level

[0076] 21 Floor

[0077] 22 Longitudinal axis of a conveyor unit

[0078] 24, 26 Open space of the load carrier

[0079] 25 Sensor system

[0080] 30 Drive System

[0081] 40-43 sensor units

[0082] 40a-43a Detection ranges of the respective sensor units

[0083] 51-54 Drive unit oc Minimum detection angle ß Solid angle detection range y Tilt angle d Distance between floor and detection plane h Distance between the top edge of the load carrier and the detection plane

Claims

Lawyer's file: P102372WOXX Applicant: FILICS GmbH Claims 1. Method for controlling a material handling device (10) for conveying a loaded or unloaded load carrier (16), with two independently movable controllable conveying units (12a, 12b), wherein each conveying unit (12a, 12b) comprises: a chassis, at least one drive system (30) which drives at least one floor roller of the conveying unit (12a, 12b), at least one support element (18) for supporting the load carrier (16), a control system (1), and a sensor system (25;40-43) for detecting environmental parameters, which is coupled or connected to the control system (1), wherein each conveying unit (12a, 12b) is movable relative to the other conveying unit (12a, 12b) and independently of the other conveying unit (12a, 12b) along any direction of travel, and the conveying units (12a, 12b) can interact to convey a load carrier (16), wherein the conveying units (12a, 12b) are or are coupled to each other for control purposes in order to perform synchronized movements, wherein a control system (1a) of the first conveying unit (12a) controls the first conveying unit (12a) and the second conveying unit (12b) so that both conveying units (12a, 12b) can perform synchronized movements, characterized in that the control system (1b) of the second conveying unit (12b) controls the first conveying unit (12a) and the second conveying unit (12b). The conveying unit (12b) takes over when the sensor system (25;42, 43) the second conveying unit (12b) reports safety-relevant information and / or detects a violation of a safety protection field and / or an emergency stop signal is present at the second conveying unit (12b).; 2. Method according to claim 1, wherein the sensors (40-43) of the first conveying unit (12a) and the second conveying unit (12b) detect data in the vicinity of the respective conveying unit (12a, 12b) in order to check or determine whether there is an obstacle in the detection range of the sensors (40-43).

3. Method according to one of the preceding claims, wherein in each conveying unit (12a, 12b) an emergency stop switch (3) is coupled or connected as a sensor to the control system (1) and transmits a stop signal to the control system (1) when the emergency stop switch (3) is activated or pressed.

4. Method according to one of the preceding claims, wherein in each conveying unit (12a, 12b) a chassis sensor (2) which is coupled or connected to the control system (1) detects whether a floor roller is blocked or spinning freely and / or a lifting mechanism sensor which is coupled or connected to the control system (1) detects whether the lifting mechanism is blocked.

5. Method according to one of the preceding claims, wherein control signals are transmitted unidirectionally only from the controlling conveying unit (12a) to the controlled conveying unit (12b) (Master -> Slave).

6. Method according to one of the preceding claims, wherein sensor data or safety-relevant data are transmitted or exchanged bidirectionally between the first conveying unit (12a) and the second conveying unit (12b) (Master <-> Slave).

7. Method according to one of the preceding claims, wherein data transmission between the first conveying unit (12a) and the second conveying unit (12b) for motion control only takes place when the support element (18) is not completely lowered or raised.

8. Method according to one of the preceding claims, wherein the control system (1) of each conveying unit (12a, 12b) slows down or stops the respective conveying unit (12a, 12b) when the data connection between the conveying units (12a, 12b) is interrupted or is interrupted for more than a predetermined period of time (dead man's switch).

9. A method according to any of the preceding claims, wherein the conveying unit (12a) controlling both conveying units (12a, 12b) continues to perform overall control of the conveying units (12a, 12b) until a safety-relevant signal is detected by the controlled conveying unit (12b), whereupon the previously controlled conveying unit (12b) transmits this to the previously controlled The conveying unit (12a) is notified and takes over the overall control from the previously controlling conveying unit (12a), which can be done for a specified period of time, or until a safety-relevant signal is detected by the now controlled conveying unit (12a), whereupon it takes over the overall control again.

10. Industrial conveying device (10) for conveying a loaded or unloaded load carrier (16), comprising two independently movable, controllable conveying units (12a, 12b), each conveying unit (12a, 12b) comprising: a chassis, at least one drive system (30) which drives at least one floor roller of the conveying unit (12a, 12b), at least one support element (18) for supporting the load carrier (16), a control system (1), and a sensor system (25; 40-43) for detecting environmental parameters, each conveying unit (12a, 12b) being movable relative to and independently of the other conveying unit (12a, 12b) along any direction of travel, and the conveying units (12a, 12b) being able to work together to convey a load carrier (16), wherein the conveying units (12a, 12b) can be coupled together in terms of control technology to execute synchronized movements,wherein a control system (1a) of the first conveying unit (12a) can take over the control of this first conveying unit (12a) and the control of the second conveying unit (12b), so that both conveying units (12a, 12b) can perform synchronized movements which are controlled by the control system (1a) of the first conveying unit (12a), characterized in that the control system (1b) of the second conveying unit (12b) can take over the control of the first conveying unit (12a) and the control of the second conveying unit (12b) when the sensor system (25; 42, 43) of the second conveying unit (12b) reports safety-relevant information and / or detects a violation of a safety protection field and / or an emergency stop signal is present at the second conveying unit (12b).

11. Industrial transport device according to the preceding claim, wherein the sensor system (25) comprises one or more optical sensors (40-43) or laser scanners, which are located at each The conveying unit (12a, 12b) is preferably arranged on a front and a rear side.

12. Industrial transport device according to one of the two preceding claims, wherein the chassis of each conveying unit (12a, 12b) has a chassis sensor (2) to detect whether a floor roller is blocked or spinning freely.

13. Industrial transport device according to one of the three preceding claims, wherein in each conveying unit (12a, 12b) an emergency stop switch (3) is part of the sensor system (25).

14. Industrial transport device according to one of the four preceding claims, wherein each conveying unit (12a, 12b) has a communication unit (4) for transmitting and / or receiving or exchanging control signals and / or sensor signals with one or more other conveying units (12a, 12b) which is connected to the control system (1) and / or a sensor (40-43).

15. Material handling device according to one of the five preceding claims, wherein each conveying unit (12a, 12b) has an emergency braking or emergency stopping device (5) which can cause the conveying unit (12a, 12b) to brake or stop if a loss of contact in the data connection between the conveying units (12a, 12b) is detected, or a communication interruption between the conveying units (12a, 12b) is detected which lasts for longer than a predetermined time period (dead man's switch), such as more than 100 milliseconds or more than 1 second.

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