METHOD FOR OPERATING AN INDUSTRIAL TRUCK AND INDUSTRIAL TRUCK

Description

[0001] The invention relates to a method for operating an industrial truck traveling on wheel tires, in particular superelastic tires or pneumatic tires, on a traveling floor, wherein vehicle properties of the industrial truck are controlled by a vehicle control device and tire wear of the wheel tires is measured by a tire wear measuring device, as well as an industrial truck for carrying out the method.

[0002] So-called superelastic tires are predominantly used as wheel tires for industrial trucks, especially forklifts. Unlike car tires, these tires can withstand quite a bit of wear. These are not usually air-filled tires, but solid rubber tires. They usually consist of several layers of different materials, and the tires can be worn down almost to the base layer.

[0003] Automated industrial trucks (also known as autonomous vehicles or "Automated Guided Vehicles" (AGVs)) currently primarily use low-wear rubber tires, which, however, can only operate reliably on high-quality, i.e., even, surfaces. As autonomous industrial trucks become more widespread, these autonomous trucks will increasingly be required to operate on poorer surfaces or outdoors, requiring the use of superelastic or pneumatic tires.

[0004] Since these superelastic tires wear significantly more rapidly over their service life than rubber tires, this can sometimes lead to the truck tilting. This can happen, for example, if the front wheels wear more than the rear wheels.

[0005] Typically, the vertical position of an industrial truck's mast is set and "taught" once during assembly. This is also the case with a driverless and thus autonomous industrial truck with a mast. If the truck tilts forward or backward during operation due to tire wear, the supposedly vertical position of the mast is no longer vertical and must be corrected by re-teaching, especially in autonomous industrial trucks. In a manned industrial truck, the driver compensates for such errors by manually tilting the mast.

[0006] The collision sensors commonly used in autonomous industrial trucks to protect the truck from collisions, which can be implemented as laser scanners, must also be aligned so that the scanning plane of the collision sensor is horizontal, i.e., parallel to the ground. This is not a problem when operating an autonomous industrial truck with rubber tires due to the low tire wear. However, when operating an autonomous industrial truck with superelastic tires or pneumatic tires, a vehicle tilt due to tire wear can lead to, for example, a person lying on the ground no longer being detected in time or, in extreme cases, not being detected at all.

[0007] The inclination of the industrial truck, especially an autonomous industrial truck, as a result of tire wear leads to the fact that, for example, the lifting mast is no longer exactly vertical and, particularly in the case of autonomous industrial trucks, problems arise when the forks automatically insert into a pallet or wire mesh box.

[0008] Furthermore, in autonomous industrial trucks, tire wear can cause the collision sensor, such as a laser scanner, to no longer be aligned exactly parallel to the ground, which negatively impacts the range of the collision sensor. In one extreme case, the scanning plane is tilted downwards, so that the collision sensor can no longer see far enough ahead. In the other extreme case, the collision sensor is tilted upwards, so that it no longer detects flat obstacles lying on the ground. Consequently, an autonomous and therefore driverless industrial truck must be designed for this worst-case scenario. This means that, due to the reduced range of the collision sensor, the vehicle speed must be significantly reduced so that the autonomous industrial truck can be stopped and come to a standstill before reaching an obstacle.DE 10 2011 053963 A1 discloses a method according to the preamble of claim 1, as well as an industrial truck for carrying out the method.

[0009] The present invention is based on the object of designing a method and an industrial truck of the type mentioned above in such a way that the negative effects of tire wear on the vehicle properties are reduced.

[0010] This object is achieved according to the invention in terms of the method in that at least one vehicle property of the industrial truck is actively influenced by the vehicle control device as a function of the tire wear of the wheel tires, wherein a maximum permissible travel speed of the industrial truck is used as the vehicle property, which is actively changed as a function of the tire wear of the wheel tires, in particular the maximum permissible travel speed in the reverse direction, wherein the maximum permissible travel speed is adapted as a function of a change in the position and / or orientation of a collision sensor arranged on the industrial truck with respect to the running floor as a result of the tire wear of the wheel tires.

[0011] The invention is based on the idea that the effects of tire wear can be compensated for by actively intervening in the vehicle's characteristics by the vehicle control system. For this purpose, tire wear is measured, and after evaluating the measurement results, the vehicle control system performs targeted intervention.

[0012] In a preferred embodiment of the invention, at least one variable orientation of a vehicle device is used as a vehicle property, wherein the orientation is changed depending on the tire wear of the wheel tires in such a way that an inclination of the industrial truck due to the tire wear of the wheel tires is compensated. For example, if the vehicle device tilts with the vehicle's longitudinal axis due to the different tire wear on the front and rear wheel axles of the industrial truck, the effect of the tire wear can be compensated by rotating the vehicle device in the opposite direction to the direction of inclination. This ensures that the absolute spatial orientation of the vehicle device is maintained even in the event of tire wear.

[0013] Advantageously, a load handling device of the industrial truck is used as the vehicle device, wherein the alignment of the load handling device relative to the industrial truck is actively changed depending on the tire wear of the wheel tires so that the absolute alignment of the load handling device relative to the running floor remains constant.

[0014] In a particularly advantageous embodiment, a lifting mast is used as the load-handling device. Furthermore, the alignment of the lifting mast relative to the industrial truck is actively adjusted depending on the tire wear of the wheels, so that the absolute alignment of the lifting mast remains vertical.

[0015] A further preferred embodiment provides for forks to be used as load handling equipment, and the alignment of the forks relative to the industrial truck is actively changed depending on the tire wear of the wheels so that the absolute alignment of the forks remains horizontal. This ensures that even in driverless, automated operation of the industrial truck, the forks are always aligned horizontally, regardless of the tire wear. This allows the forks to insert cleanly into pallets or wire mesh crates at all times. Another advantage of operation with a driver is that there is no need to manually correct the alignment of the forks, thus increasing operating comfort.

[0016] In a particularly preferred embodiment, a collision sensor of the industrial truck is used as the vehicle device, wherein the alignment of the collision sensor relative to the industrial truck is actively changed depending on the tire wear of the wheels so that the absolute alignment of the collision sensor relative to the running surface remains constant. This prevents the collision sensor from no longer being aligned exactly parallel to the running surface, for example due to the inclination of the industrial truck as a result of uneven tire wear on the wheel axles of the industrial truck. The correction by the vehicle control device ensures that the parallel alignment is maintained, thus ensuring the optimal range of the collision sensor.

[0017] According to the invention, a maximum permissible driving speed of the industrial truck is used as a vehicle characteristic, which is actively varied depending on the tire wear. This ensures that the industrial truck remains in a safe operating condition even when the tire wear is advanced.

[0018] According to the invention, the maximum permissible travel speed is adjusted depending on a change in the position and / or orientation of a collision sensor arranged on the industrial truck relative to the running surface due to tire wear. The maximum permissible travel speed is advantageously adjusted in such a way that the industrial truck can be stopped within the range of the collision sensor.

[0019] With precise knowledge of the current position of the collision sensor, in particular its height above the running surface, and the orientation of the collision sensor, in particular its angle of inclination (which depends on tire wear) relative to the running surface, it is possible to calculate exactly how far the collision sensor's measuring beam reaches, depending on the tire wear, until it hits the running surface, or until it can no longer detect obstacles of a specified height of, for example, 200 mm. This, in turn, can be used to deduce the maximum speed the industrial truck can travel with the current tire wear so that the industrial truck can be stopped and come to a stop in time before an obstacle is encountered. This maximum travel speed can be continuously adjusted at specific intervals, for example daily or weekly, depending on tire wear.This means that the industrial truck can be operated safely and efficiently even in automated mode.

[0020] It is advisable to determine the tire wear by means of at least one distance sensor arranged on the industrial truck, which measures the distance of the distance sensor to the running floor.

[0021] In a variant of the invention, which requires particularly low technical effort, the distance sensor measures the distance from the distance sensor to the running surface along a measuring path aligned perpendicular to the running surface. In this way, the vertical distance of the vehicle to the running surface can be directly determined at a specific point on the industrial truck, preferably in the area of ​​a wheel axle. The change in the vertical distance during the vehicle's operating time can be used to determine the change in the tire diameter and thus the tire wear on this wheel axle.

[0022] Another advantageous variant of the invention provides that the distance sensor measures the distance from the distance sensor to the running floor along a measuring section inclined at an angle to the running floor. From the distance to the point of contact of the measuring section with the running floor and the angle of inclination, the vertical distance to the running floor can be calculated in a data processing device, in particular in the vehicle control device. In this way, the vertical distance of the vehicle to the running floor can be determined at a specific point on the industrial truck, preferably in the area of ​​a wheel axle. The change in the vertical distance during the vehicle's operating time can be used to determine the change in the tire diameter and thus the tire wear on this wheel axle.

[0023] The angle of inclination can be fixed, for example, due to the distance sensor being mounted at an angle on the vehicle.

[0024] According to a preferred embodiment of the invention, however, the angle of inclination is variable, wherein the angle of inclination is measured by means of an inclination sensor.

[0025] During the measuring process, the distance sensor is preferably moved from a starting position with the measuring section aligned parallel to the running floor to a measuring position with the measuring section inclined by the inclination angle to the running floor. The vertical distance and thus the vertical distance (height) of the distance sensor from the running floor is then calculated in the data processing device, for example, the vehicle control device, from the distance of the distance sensor to the point of contact of the measuring section with the running floor measured by the distance sensor and the inclination angle of the measuring section measured by the inclination sensor.If this measurement is carried out periodically at intervals, for example daily, at a defined location where the running surface is level and undamaged, the change in the height of the distance sensor above the running surface results in the temporal change in the tire diameter and thus the tire wear on the wheel axle located in the area of ​​the distance sensor.

[0026] A distance sensor arranged on a tiltable device, in particular a lifting mast of an industrial truck, is expediently used as the distance sensor.

[0027] In a particularly advantageous embodiment of the invention, a collision sensor provided for collision protection of the industrial truck is used as the distance sensor. In this way, a collision sensor already present on the industrial truck can be used to measure tire wear. This can save investment costs. During normal operation, the distance sensor can remain in its starting position with the measuring path aligned parallel to the running floor, for example, monitoring the space in front of the industrial truck and thus serving as a collision protection sensor. At intervals, for example once a day before the start of normal operation, the distance sensor can be moved from the starting position to the measuring position with an inclined measuring path in order to perform the tire wear measurement.

[0028] Especially in the case of an automated vehicle, it is particularly advantageous to use a distance sensor already present for collision protection, i.e. a collision protection sensor, also for determining tire wear.

[0029] An optical sensor, in particular a laser scanner (e.g., a 1D, 2D, or 3D laser scanner), a camera (e.g., a stereo camera, a time-of-flight camera, or an ultrasonic sensor) can be used as a distance sensor. Especially in automated vehicles, a laser scanner and / or a camera for collision protection are usually already installed and can be easily used to measure tire wear using a tiltable device.

[0030] According to a particularly preferred embodiment of the invention, in an industrial truck with at least two wheel axles, it is provided that the distance of the distance sensor from the running floor in the area of ​​one of the wheel axles is measured by means of the distance sensor, and the change in the tire diameter on the measured wheel axle is determined from a change in this measured value and the change in the tire diameter on the non-measured wheel axle is determined from the pitch angle of the imaginary connecting axis between the wheel axles of the industrial truck for a given wheelbase, measured by a position sensor.

[0031] For example, by comparing the pitch angle with the original tire condition, when new, unworn tires are present, it can be determined whether the tire wear on the non-measured wheel axle is the same (i.e., the relative pitch angle = 0), greater (i.e., the relative pitch angle > 0), or less (i.e., the relative pitch angle < 0) than the tire wear on the measured wheel axle. Using the wheelbase, the absolute tire wear on the non-measured wheel axle can be calculated.

[0032] The invention further relates to an industrial truck for carrying out the method with a vehicle control device and a tire wear measuring device.

[0033] In the industrial truck, the stated object is achieved in that the vehicle control device is operatively connected to the tire wear measuring device, and the vehicle control device is configured to evaluate measured values ​​transmitted by the tire wear measuring device and to actively influence at least one vehicle property of the industrial truck depending on the tire wear.

[0034] The industrial truck is preferably designed as a forklift truck, tractor, platform truck, pallet truck, reach truck or order picking vehicle.

[0035] It is particularly advantageous if the industrial truck is designed as an autonomous vehicle, in particular as an autonomous transport vehicle or as a mobile order picking robot.

[0036] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Figure 1an autonomous industrial truck with new wheel tires, Figure 2the industrial truck from Figure 1 with worn tyres on the front wheel axle, and Figure 3 the industrial truck from Figure 1 when measuring tire wear.

[0037] In Figure 1 An autonomous industrial truck 1 is shown. The industrial truck is designed, for example, as a forklift.

[0038] The industrial truck 1 has a vehicle chassis with two wheel axles 5, 9, of which, in the illustrated embodiment, the wheel axle 5 is designed as the front axle and the wheel axle 9 as the rear axle. The wheel axle 5 designed as the front axle is provided with one or two wheel tires 10, which are designed as superelastic tires or pneumatic tires. The wheel axle 9 designed as the rear axle is provided with one or two wheel tires 11, which are designed as superelastic tires or pneumatic tires. The industrial truck rests on a running surface 7 with the wheel tires 10, 11.

[0039] In the illustrated embodiment, the industrial truck 1 is equipped with a lifting mast 6, on which a load-handling device 20 in the form of a load fork with two forks is arranged, which can be raised and lowered. The lifting mast 6 can be tilted about a horizontal transverse axis.

[0040] The autonomous industrial truck 1 has two distance sensors 2 and 12, a position sensor 3, and an inclination sensor 4. The distance sensors 2 and 12 are each designed, for example, as 2D laser scanners and serve as collision sensors 16 and 17 for collision protection of the autonomous industrial truck 1. The distance sensor 2 or collision sensor 16 is mounted near the front wheel axle 5 of the vehicle 1, in the illustrated embodiment 1 on the tiltable lifting mast 6, and secures the front area of ​​the industrial truck 1. The scanning plane of the distance sensor 2 or collision sensor 16 in the starting position is aligned parallel to the running floor 7. The second distance sensor 12 or collision sensor 17 is arranged near the rear wheel axle 9 and secures the rear area of ​​the industrial truck 1. The scanning plane of the distance sensor 12 or collision sensor 17 in the starting position is also aligned parallel to the traveling floor 7.

[0041] The tilt sensor 4 is arranged on the tiltable lifting mast 6. The tilt sensor 4 is preferably designed as an absolute position sensor.

[0042] The position sensor 3 is located in or on the vehicle chassis of the industrial truck 1. The position sensor 3 is preferably designed as an absolute measuring position sensor.

[0043] In a vehicle control device 8, the measured values ​​of the distance sensors 2 and 12 or collision sensors 16 and 17 as well as the position sensor 3 and the inclination sensor 4 are evaluated and taken into account when controlling the industrial truck 1.

[0044] The Figure 1shows the autonomous industrial truck 1 with new tires 10 and 11 on the wheel axles 5 and 9, which are designed as super-elastic tires or pneumatic tires. The industrial truck 1 is positioned horizontally on the running surface 7, and the scanning planes of the distance sensors 2 and 12 and the collision sensors 16 and 17 are aligned exactly parallel to the running surface 7. The distance sensors 2 and 12 and the collision sensors 16 and 17 can thus detect obstacles 13, 14 located far away on the running surface 7.

[0045] In the Figure 2 is the industrial truck 1 from the Figure 1with worn wheel tires 10 on the front wheel axle 5. On the rear wheel axle 9, however, new wheel tires 11 are mounted. This results in the industrial truck 1 being tilted forward along the vehicle's longitudinal axis. As a result, the distance sensors 2 and 12, or the collision sensors 16 and 17, are no longer aligned exactly parallel to the running surface 7, which negatively affects their range. The scanning plane of the front distance sensor 2, or collision sensor 16, is tilted downward, so that the distance sensor 2, or collision sensor 16, can no longer see far enough ahead. Therefore, the distance sensor 2, or collision sensor 16, can no longer detect the obstacle 13. On the other hand, the scanning plane of the rear distance sensor 12 or collision sensor 17 is inclined upwards, so that the distance sensor 12 or collision sensor 17 can no longer detect the obstacle 14 lying flat on the running floor 7.

[0046] This situation of Figure 2 can be determined by a tire wear measurement, as used in connection with the Figure 3explained in more detail, and taken into account in the vehicle control device 8. In this case, in order to compensate for the negative effects of tire wear, the vehicle control device 8 can issue the control command to tilt the lifting mast 6 against the direction of inclination of the industrial truck 1 until it is again aligned absolutely vertically in space. The absolute alignment of the lifting mast 6 is measured by the absolute measuring tilt sensor 4. The vertical alignment of the lifting mast 6 has the effect that the scanning plane of the distance sensor 2 or collision sensor 16 attached to the lifting mast 6 is again aligned exactly parallel to the running surface 7, regardless of the tire wear. The obstacle 13 can thus be detected again.The vertical alignment of the lifting mast 6 also means that the load handling device 20 is always aligned horizontally, regardless of tire wear, so that the forks can insert cleanly into pallets or wire mesh boxes and the autonomous industrial truck 1 can pick up and set down pallets or wire mesh boxes safely and easily, regardless of tire wear.

[0047] The negative effects of tire wear on the front wheel axle 5 are compensated according to the invention by limiting the maximum permissible travel speed, particularly in the reverse direction, in the vehicle control device 8. The maximum permissible travel speed is adjusted and reduced in such a way that the industrial truck 1 can be stopped within the shortened range of the downwardly inclined distance sensor 2 or collision sensor 16 and / or within the range when the upwardly inclined distance sensor 12 or collision sensor 17 detects the obstacle 14 lying flat on the running surface 7.

[0048] With the precise knowledge of the current position of the distance sensor 2 or collision sensor 16 and the distance sensor 12 or collision sensor 17, in particular their height above the running surface 7, and the orientation of the distance sensor 2 or collision sensor 16 and the distance sensor 12 or collision sensor 17, in particular their angle of inclination relative to the running surface 7, it is possible to calculate exactly how far the measuring beam of the distance sensor 2 or collision sensor 16 on the front wheel axle 5 reaches until it hits the running surface 7, or how far the measuring beam of the distance sensor 12 or collision sensor 17 can see until it can no longer detect the obstacle 14 from a predetermined height of, for example, 200 mm.This in turn can be used to determine the maximum speed the autonomous industrial truck can travel with the current tire wear, especially in reverse, so that industrial truck 1 can be stopped and come to a complete stop in time before obstacle 13 or 14. This maximum travel speed can be continuously adjusted at specific intervals, for example, daily or weekly, depending on tire wear. Thus, industrial truck 1 can be operated safely and efficiently even in automated mode.

[0049] In the Figure 3Illustrated is the tire wear measurement using the tire wear measuring device 15, which comprises the distance sensor 2 or collision sensor 16 on the tiltable lifting mast 6, the tilt sensor 4 and the position sensor 3, as well as the vehicle control device 8. If the tiltable lifting mast 6 is tilted such that the measuring beam of the distance sensor 2 or collision sensor 16 reaches the running floor 7, the distance sensor 2 or collision sensor 16 can measure and output the distance I up to the point of contact of its measuring beam with the running floor 7, as shown in the detailed sketch at the bottom left. In conjunction with the tilt angle α of the tiltable lifting mast 6, which is measured and output by the tilt sensor 4, the height h of the distance sensor 2 or collision sensor 16 above the running floor 7 can now be determined in the vehicle control device 8 according to the formula h = I x sin (α).If this measurement is carried out daily at a defined location where the running surface 7 is level and undamaged, the change in the height h of the distance sensor 2 or collision sensor 16 above the running surface 7 results in the daily change in the tire diameter and thus the tire wear of the wheel tires 10 on the front wheel axle 5.

[0050] The position sensor 3 is attached to or in the vehicle chassis of the vehicle 1 and measures the current pitch angle of the vehicle 1 along the vehicle's longitudinal axis. By comparing it with the pitch angle in the original state, in which the wheel tires 10, 11 are new and not yet worn, it can be determined whether the tire wear of the wheel tires 11 on the rear wheel axle 9 is the same (i.e., the relative pitch angle = 0), or greater (i.e., the relative pitch angle > 0), or smaller (i.e., the relative pitch angle < 0) than the tire wear of the wheel tires 10 on the front wheel axle 5. Using the wheelbase, the absolute tire wear of the wheel tires 11 on the rear wheel axle 9 can be calculated in the vehicle control device 8.

[0051] The vehicle control device 8 can thus use the distance sensor 2, the tilt sensor 4 and the position sensor 3 to determine the tire wear on the wheel tires 10, 11, which are designed as superelastic tires or pneumatic tires, on the front axle and the rear axle of the autonomous industrial truck 1 and to detect and calculate the position (height above the running floor 7) and orientation (angle of inclination relative to the running floor 7) of the distance sensors 2, 12 resulting from the tire wear.

[0052] With the integration of the front load-side distance sensor 2, which also serves as a collision sensor 16 for obstacle detection, into the lifting mast 6, the distance sensor 2 or collision sensor 16 can be tilted together with the lifting mast 6. Thus, the existing collision sensor 16 can also be used to determine tire wear on the front wheel axle 5. Furthermore, the collision sensor 16 is protected by being positioned between the lifting mast profiles of the lifting mast 6 and thus does not protrude beyond the vehicle contour, thereby reducing the risk of damage.

[0053] By using the tilt sensor 4, which is designed as an absolute measuring position sensor, on the tiltable lifting mast 6, the operation of an autonomous industrial truck 1 with wheel tires 10, 11 designed as super-elastic tires is only meaningfully possible, since by tilting the lifting mast 6 accordingly, an inclination of the load handling device 20 caused by tire wear can be compensated and it can be achieved that the load handling device 20 is always aligned horizontally regardless of tire wear, so that a clean insertion of the forks into pallets or wire mesh boxes is possible and the autonomous industrial truck 1 can pick up and set down pallets or wire mesh boxes safely and easily regardless of tire wear.

[0054] Adapting the maximum travel speed of the autonomous industrial truck to the tire wear of the wheel tires 10, 11 designed as superelastic tires or pneumatic tires continues to enable efficient use of the autonomous industrial truck 1 with wheel tires 10, 11 designed as superelastic tires or pneumatic tires, since higher maximum travel speeds can be permitted with new wheel tires 10, 11 than with unevenly worn wheel tires 10, 11.

Claims

1. Method for operating an industrial truck (1) driving over a driving surface (7) on wheel tyres (10, 11), in particular superelastic tyres or pneumatic tyres, wherein vehicle characteristics of the industrial truck (1) are controlled by a vehicle control device (8) and tyre wear of the wheel tyres (10, 11) is measured by a tyre wear measuring device (15), wherein at least one vehicle characteristic of the industrial truck (1) is actively influenced by the vehicle control device (8) as a function of the tyre wear of the wheel tyres (10, 11), wherein a maximum permissible driving speed of the industrial truck (1), which is changed actively as a function of the tyre wear of the wheel tyres (10, 11), is used as the vehicle characteristic, in particular the maximum permissible driving speed in the reverse direction of travel, characterized in that the maximum permissible driving speed is adapted as a function of a change in the position and / or orientation of a collision sensor (16; 17) arranged on the industrial truck (1) relative to the driving surface (7) caused by the tyre wear of the wheel tyres (10, 11).

2. Method according to Claim 1, characterized in that at least one changeable orientation of a vehicle apparatus is used as the vehicle characteristic, wherein the orientation is changed as a function of the tyre wear of the wheel tyres (10, 11) so as to compensate for an inclination of the industrial truck (1) caused by the tyre wear of the wheel tyres (10, 11).

3. Method according to Claim 2, characterized in that a load-carrying means of the industrial truck (1) is used as the vehicle apparatus, wherein the orientation of the load-carrying means relative to the industrial truck (1) is changed actively as a function of the tyre wear of the wheel tyres (10, 11) such that the absolute orientation of the load-carrying means relative to the driving surface (7) remains constant.

4. Method according to Claim 3, characterized in that a lift mast (6) is used as the load-carrying means, and the orientation of the lift mast (6) relative to the industrial truck (1) is changed actively as a function of the tyre wear of the wheel tyres (10, 11) such that the absolute orientation of the lift mast (6) remains vertical.

5. Method according to Claim 3 or 4, characterized in that fork arms are used as the load-carrying means, and the orientation of the fork arms relative to the industrial truck (1) is changed actively as a function of the tyre wear of the wheel tyres (10, 11) such that the absolute orientation of the fork arms remains horizontal.

6. Method according to one of Claims 2 to 5, characterized in that a collision sensor (16) of the industrial truck (1) is used as the vehicle apparatus, wherein the orientation of the collision sensor (16) relative to the industrial truck (1) is changed actively as a function of the tyre wear of the wheel tyres (10, 11) such that the absolute orientation of the collision sensor (16) relative to the driving surface (7) remains constant.

7. Method according to Claim 1, characterized in that the maximum permissible driving speed is adapted such that the industrial truck (1) is able to be stopped within the range of the collision sensor (16; 17).

8. Method according to one of Claims 1 to 7, characterized in that the tyre wear is determined by way of at least one distance sensor (2) that is arranged on the industrial truck (1) and measures the distance from the distance sensor (2) to the driving surface (7).

9. Method according to Claim 8, characterized in that the distance sensor (2) measures the distance from the distance sensor (2) to the driving surface (7) along a measurement path oriented perpendicular to the driving surface (7).

10. Method according to Claim 8, characterized in that the distance sensor (2) measures the distance from the distance sensor (2) to the driving surface (7) along a measurement path oriented in a manner inclined by an angle of inclination (α) with respect to the driving surface (7).

11. Method according to Claim 10, characterized in that the angle of inclination (α) is fixed.

12. Method according to Claim 10, characterized in that the angle of inclination (α) is variable, wherein the angle of inclination (α) is measured by way of a tilt sensor (4).

13. Method according to Claim 12, characterized in that the distance sensor (2) is brought, during the measurement process, from a starting position with a measurement path oriented parallel to the driving surface (7) to a measuring position with a measurement path oriented in a manner inclined by the angle of inclination (α) with respect to the driving surface (7), and the vertical distance from the distance sensor (2) to the driving surface (7) is computed from the measured distance from the distance sensor (2) to the point of contact between the measurement path and the driving surface (7) and the measured angle of inclination (α) of the measurement path.

14. Method according to one of Claims 8 to 13, characterized in that a distance sensor (2) arranged on a tiltable apparatus, in particular a lift mast (6) of the industrial truck (1), is used as the distance sensor (2).

15. Method according to one of Claims 8 to 14, characterized in that a collision sensor (16) of the industrial truck (1) is used as the distance sensor (2).

16. Method according to one of Claims 8 to 15, characterized in that an optical sensor, in particular a laser scanner or a camera, or an ultrasonic sensor is used as the distance sensor (2).

17. Method according to one of Claims 8 to 16, characterized in that, in the case of an industrial truck (1) having at least two wheel axles (5, 9), the distance sensor (2) is used to measure the distance to the driving surface (7) in the region of one of the wheel axles (5), and the change in the tyre diameter on the measured wheel axle (5) is determined from a change in this measured value, and the change in the tyre diameter on the unmeasured wheel axle (9) is determined from the change in a pitch angle, measured by a position sensor (3), of the imaginary connecting axis between the wheel axles (5, 9) of the industrial truck (1), given a fixed wheelbase.

18. Industrial truck (1) for carrying out the method according to one of Claims 1 to 17 with a vehicle control device (8) and a tyre wear measuring device (15), wherein the vehicle control device (8) is operatively connected to the tyre wear measuring device (15), and the vehicle control device (8) is configured to evaluate measured values transmitted by the tyre wear measuring device (15) and to actively influence at least one vehicle characteristic of the industrial truck (1) as a function of the tyre wear.

19. Industrial truck (1) according to Claim 18, characterized in that it is in the form of a forklift truck, tractor, platform truck, pallet truck, reach truck or picking vehicle.

20. Industrial truck (1) according to Claim 18 or 19, characterized in that it is in the form of an autonomous vehicle, in particular an autonomous transport vehicle or a mobile picking robot.