Warning device, warning method, and warning program

Abstract

To provide a warning device, a method for warning, and a warning program that can evaluate the risk of falling of a vehicle at low cost and can issue a proper warning to the user or the manager of the vehicle.SOLUTION: The warning device, the method for warning, and the warning program acquire rotation number information showing the number of rotations of each wheel of a vehicle with a loading unit, and acquires the position of the vehicle. The warning device, the method for warning, and the warning program also determine whether a road surface on which the vehicle is running is in a warning target state, and relates state data showing the vehicle is in a warning target state and the vehicle position to each other and outputs the data if the road surface has been determined to be in a warning target state.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a warning device, a warning method, and a warning program. [Background technology]

[0002] The technology disclosed in Patent Document 1 calculates a distance conversion coefficient (a coefficient that converts the number of wheel rotations into a traveled distance) when a vehicle travels at each point in an identification area set on the road surface on which the vehicle is traveling, and then identifies the road surface condition according to the statistical distribution (frequency distribution) of the time-series data of the obtained distance conversion coefficient. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-197819 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the technology disclosed in Patent Document 1, it is necessary to install optical beacons and roadside devices on the road surface in addition to the on-board device, which may increase the cost of identifying road surface conditions. Furthermore, it is not possible to identify road surface conditions using only the on-board device. Therefore, it is not possible to evaluate the risk of a vehicle tipping over at low cost.

[0005] The present invention has been made in view of the problems inherent in the prior art, and an object of the present invention is to provide a warning device, a warning method, and a warning program that can evaluate the risk of a vehicle tipping over at low cost and issue an appropriate warning to a vehicle user or manager. [Means for solving the problem]

[0006] A warning device according to a first aspect of the present invention includes an input unit to which rotation speed information indicating the rotation speed of each of a plurality of wheels of a vehicle having a cargo loading section and the vehicle position of the vehicle are input, and a controller. The controller determines whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information, and if it is determined that the road surface is in a state requiring a warning, outputs state data indicating the state requiring a warning and the vehicle position in association with each other.

[0007] A warning method according to a second aspect of the present invention is executed by a computer, acquires rotation speed information indicating the rotation speed of each of a plurality of wheels of a vehicle having a cargo carrying section, acquires the vehicle position of the vehicle, determines whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information, and if it is determined that the road surface is in a state requiring a warning, associates state data indicating the state requiring a warning with the vehicle position and outputs the state data.

[0008] A warning program according to a third aspect of the present invention causes a computer to execute a process of acquiring rotation speed information indicating the rotation speed of each of a plurality of wheels of a vehicle having a cargo carrying section, acquiring the vehicle position of the vehicle, determining whether the road surface on which the vehicle is traveling is in a warning state based on the rotation speed information, and if it is determined that the road surface is in a warning state, outputting status data indicating the warning state in association with the vehicle position. [Effects of the Invention]

[0009] According to the present invention, it is possible to evaluate the risk of a vehicle tipping over at low cost and to issue an appropriate warning to the user or manager of the vehicle. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing a forklift to which a warning device according to an embodiment of the present invention is applied; [Figure 2] 1 is a bottom view showing a forklift to which a warning device according to an embodiment of the present invention is applied; [Figure 3] 1 is a block diagram showing an example of the configuration of a warning device according to an embodiment of the present invention; [Figure 4] 5 is a flowchart showing a first example of processing by the warning device according to the present embodiment. [Figure 5] 10 is a flowchart showing a second example of the processing of the warning device according to the present embodiment. [Figure 6] 4 is a schematic diagram showing how status data and the like are mapped by the warning device according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, the warning device according to this embodiment will be described in detail with reference to the drawings. In the description, the same components are designated by the same reference numerals and duplicated explanations will be omitted.

[0012] [Vehicle configuration example] A forklift F to which the warning device according to this embodiment is applied will be described with reference to Figures 1 and 2. Figure 1 is a side view showing the forklift to which the warning device according to this embodiment is applied. Figure 2 is a bottom view showing the forklift to which the warning device according to this embodiment is applied.

[0013] The forklift F (vehicle) is equipped with a fork section 51 that moves up and down, a backrest section 52, a mast section 53, front wheels (left front wheel TY1, right front wheel TY2) that are driving wheels, and rear wheels (left rear wheel TY3, right rear wheel TY4) that are driving wheels.

[0014] The forklift F may be an engine vehicle powered by an internal combustion engine such as a gasoline engine, or may be a battery vehicle powered by an electric motor driven by power supplied from a secondary battery (battery) that can be charged from a generator, etc.

[0015] The fork section 51 and the backrest section 52 are attached so as to be movable up and down relative to a mast section 53 fixed to the body of the forklift F. The fork section 51 and the mast section 53 together are referred to as a load carrying section.

[0016] An on-vehicle camera CM1 is provided above the mast portion 53 that supports the fork portion 51 and the mast portion 53. The on-vehicle camera CM1 captures an image of the road surface in front of the forklift F. In addition, an on-vehicle camera CM2 is provided above the rear of the forklift F. The on-vehicle camera CM2 captures an image of the road surface behind the forklift F.

[0017] The positions at which the vehicle-mounted cameras CM1 and CM2 are installed are not limited to the examples given here, as long as they are able to capture images of the road surface around the forklift F. In addition, the vehicle-mounted cameras CM1 and CM2 may capture images of the road surface to the sides of the forklift F.

[0018] A measurement unit 11 is attached to the body of the forklift F to measure the load applied to the front and rear wheels of the forklift F and the rotation speed of the front and rear wheels. FIG. 2 shows sensors WS1, WS2, WS3, and WS4 as the measurement unit 11. Sensor WS1 measures the load applied to the left front wheel TY1 and its rotation speed. Sensor WS2 measures the load applied to the right front wheel TY2 and its rotation speed. Sensor WS3 measures the load applied to the left rear wheel TY3 and its rotation speed. Sensor WS4 measures the load applied to the right rear wheel TY4 and its rotation speed.

[0019] The sensors WS1 and WS2 may measure the load and rotation speed applied to the left front wheel TY1 and the right front wheel TY2, respectively, via the axle 61. The sensors WS3 and WS4 may measure the load and rotation speed applied to the left rear wheel TY3 and the right rear wheel TY4, respectively, via the axle 62.

[0020] Additionally, an acceleration sensor (G sensor) that detects acceleration (front-rear G, left-right G, and up-down G) during movement may be attached to the body of the forklift F. The measurement unit 11 may include an acceleration sensor.

[0021] Furthermore, a position sensor that acquires position information of the forklift F may be attached to the body of the forklift F. For example, the position sensor may be a GPS sensor. The GPS sensor receives radio waves from multiple GPS (Global Positioning System) satellites and performs predetermined calculation processing to acquire latitude and longitude information representing the current position of the forklift F from the received signals. This makes it possible to acquire position information (vehicle position) of the forklift F. The measurement unit 11 may include a position sensor.

[0022] Furthermore, a temperature sensor that acquires the temperature around the forklift F may be attached to the body of the forklift F. Also, a humidity sensor that acquires the humidity around the forklift F may be attached to the body of the forklift F. The measurement unit 11 may include a temperature sensor and a humidity sensor.

[0023] The operator (driver) of the forklift F operates the steering wheel 71, the speed change lever 72, and pedals such as an accelerator pedal and a brake pedal (not shown), etc. By operating these pedals, the fork section 51 is raised and lowered, and the forklift F is caused to move forward, backward, turn right, turn left, etc., to perform cargo handling work, etc.

[0024] The vehicle to which the warning device according to this embodiment is applied is not limited to the forklift F. The vehicle may be a vehicle that loads and unloads or transports luggage, products, etc. on the premises of a factory, warehouse, etc.

[0025] [Example of warning device configuration] The configuration of the warning device 1 according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the configuration of the warning device according to this embodiment. The warning device 1 may be mounted on the forklift F, for example, or may be mounted on a terminal carried by a user or manager of the forklift F.

[0026] 3, the warning device 1 includes an input unit 21, a controller 100, and a notification unit 400. In addition, the warning device 1 may include a measurement unit 11 and a database 15. The measurement unit 11 is mounted on the forklift F, but the database 15 may be mounted on the forklift F or installed outside the forklift F.

[0027] The measurement unit 11 and the database 15 are connected to the input unit 21, and the input unit 21 and the notification unit 400 are connected to the controller 100. Here, the "connection" may be either a wired or wireless connection.

[0028] The measurement unit 11 measures the loads applied to the front and rear wheels of the forklift F and the rotation speeds of the front and rear wheels. Information relating to the loads applied to the front and rear wheels acquired by the measurement unit 11 is transmitted to the input unit 21 as load information representing the load on each of the multiple wheels of the forklift F. In addition, information relating to the rotation speeds of the front and rear wheels acquired by the measurement unit 11 is transmitted to the input unit 21 as rotation speed information representing the rotation speeds of each of the multiple wheels of the forklift F.

[0029] The measurement unit 11 may include a temperature sensor and a humidity sensor. Information on the temperature and humidity around the forklift F is transmitted to the input unit 21 as environmental information. The measurement unit 11 may also include a position sensor that acquires position information of the forklift F. The position information of the forklift F is transmitted to the input unit 21.

[0030] When the controller 100 (described later) determines that the road surface on which the forklift F is located is in a state requiring a warning, the database 15 (storage unit) stores status data indicating the state requiring a warning in association with the vehicle position of the forklift F. For example, the status data may be plotted (mapped) on a map of the road surface on which the forklift F is traveling based on the vehicle position. The database 15 may then store the map on which the status data is plotted. FIG. 6 is a schematic diagram showing how status data and the like are mapped by the warning device according to this embodiment. In FIG. 6, danger points determined to have slipperiness A and caution points determined to have slipperiness B are plotted on a facility guide map of a factory or the like.

[0031] The database 15 may store not only status data generated by the controller 100 of one specific warning device 1, but also status data output from multiple warning devices 1. The status data stored in the database 15 is transmitted to the input unit 21 as needed. The database 15 may plot the status data on a map of the road surface on which the forklift F travels immediately after receiving the status data, thereby updating the map. The database 15 may transmit the updated map to one or multiple warning devices 1 every time the map is updated.

[0032] When it is determined that the road surface on which the forklift F is traveling is in a state requiring a warning, the database 15 may store environmental information in addition to the state data indicating the state requiring a warning, in association with the vehicle position of the forklift F. The environmental information indicates the temperature or humidity around the forklift F when the forklift F is located on the road surface determined to be in a state requiring a warning. As shown in FIG. 6 , the environmental information may be plotted (mapped) on a map of the road surface on which the forklift F is traveling and stored in the database 15. The database 15 may plot the environmental information on the map of the road surface on which the forklift F is traveling and update the map immediately after receiving the environmental information. The database 15 may transmit the updated map to one or more warning devices 1 every time the map is updated.

[0033] The input unit 21 acquires information transmitted from the measurement unit 11 and the database 15. The various pieces of information acquired by the input unit 21 are transmitted to the controller 100.

[0034] The notification unit 400 notifies the user when the controller 100, which will be described later, determines that the forklift F is in a state requiring a warning.

[0035] For example, the notification unit 400 notifies that the road surface on which the forklift F is traveling has a low-mu road (a road surface with a low coefficient of friction), a step, or an incline. Additionally, the notification unit 400 notifies that caution is required when traveling the forklift F. The notification unit 400 may be a liquid crystal display, an organic EL display, or the like.

[0036] The notification unit 400 is not limited to presenting various types of information visually. The notification unit 400 may present information to the user through auditory information, or may generate vibrations to provide a stimulus for the user through the vibrations. For example, the notification unit 400 may be a sound source, an amplifier, a speaker, or the like for generating and emitting sound.

[0037] The controller 100 is a general-purpose microcomputer equipped with a CPU (Central Processing Unit), memory, and input / output units. A computer program (warning program) that functions as part of the warning device 1 is installed in the controller 100. By executing the computer program, the controller 100 functions as multiple information processing circuits (115, 120, 130).

[0038] Here, an example is shown in which the multiple information processing circuits (115, 120, 130) provided in the controller 100 are realized by software. However, it is also possible to configure the information processing circuits (115, 120, 130) by preparing dedicated hardware for executing each of the information processes described below. Also, the multiple information processing circuits (115, 120, 130) may be configured by individual hardware.

[0039] The controller 100 includes a rotation difference calculation unit 115, a position acquisition unit 120, and a determination unit 130 as a plurality of information processing circuits (115, 120, 130).

[0040] Based on the rotation speed information, the rotation difference calculation unit 115 calculates rotation speed difference information that indicates the difference in rotation speed between the multiple wheels of the forklift F. For example, the rotation difference calculation unit 115 calculates the difference in rotation speed between the left front wheel TY1 and the right front wheel TY2 of the forklift F as the first difference.

[0041] The rotation difference calculation unit 115 may also calculate the difference between the rotation speed of the front wheels and the rotation speed of the rear wheels of the forklift F as the second difference. Here, the rotation speed of the front wheels is given by the average value of the rotation speed of the left front wheel TY1 and the rotation speed of the right front wheel TY2. Also, the rotation speed of the rear wheels is given by the average value of the rotation speed of the left rear wheel TY3 and the rotation speed of the right rear wheel TY4.

[0042] The reason why the rotation difference calculation unit 115 calculates the difference for the front wheels in the above description is that the fork section 51 serving as the load carrying section is located on the front wheel side of the forklift F (particularly, forward of the front wheels when viewed from the body of the forklift F). This is because the difference in rotation speed between the front wheels of the forklift F is useful for assessing the risk of the forklift F tipping over. However, the rotation difference calculation unit 115 may also calculate the difference in rotation speed between the left rear wheel TY3 and the right rear wheel TY4 of the forklift F as the third difference.

[0043] The position acquisition unit 120 acquires the vehicle position of the forklift F via the input unit 21. For example, the position acquisition unit 120 may acquire the vehicle position of the forklift F based on position information of the forklift F acquired by a position sensor. Alternatively, the position acquisition unit 120 may acquire the vehicle position of the forklift F by odometry based on the number of rotations of the wheels.

[0044] The determination unit 130 determines whether the road surface on which the forklift F is traveling is in a state requiring a warning, based on the rotation speed information or the rotation speed difference information. For example, the determination unit 130 determines that the road surface is in a state requiring a warning when the first difference calculated by the rotation speed difference calculation unit 115 is equal to or greater than a first threshold value. Here, the first threshold value may be determined in advance as a predetermined rotation speed, or may be a rotation speed obtained by multiplying the rotation speed of the front wheels by a predetermined coefficient.

[0045] Furthermore, the determination unit 130 may determine that the road surface is in a state requiring a warning when the second difference calculated by the rotation difference calculation unit 115 is equal to or greater than a second threshold value. Here, the second threshold value may be determined in advance as a predetermined rotation speed, or may be a rotation speed obtained by multiplying the average value of the rotation speeds of the front and rear wheels by a predetermined coefficient.

[0046] Alternatively, the determination unit 130 may determine that the road surface is in a state requiring a warning when the third difference calculated by the rotation difference calculation unit 115 is equal to or greater than a third threshold value. Here, the third threshold value may be determined in advance as a predetermined rotation speed, or may be a rotation speed obtained by multiplying the rotation speed of the rear wheels by a predetermined coefficient.

[0047] The predetermined coefficients used to determine the first, second, and third thresholds are coefficients that define the strictness of the determination when determining that the road surface is in a state requiring a warning. For example, the magnitude of the predetermined coefficients may be changed depending on the content of the notification when notifying that the road surface is in a state requiring a warning.

[0048] For example, when the steering wheel angle is large, the difference in rotation speed between the wheels tends to become large even when wheel spin does not occur. Therefore, the determination unit 130 may obtain the steering wheel angle of the forklift F using a steering wheel angle sensor (not shown) or the like, and set the predetermined coefficient based on the obtained steering wheel angle. More specifically, when the steering wheel angle is large, the determination unit 130 may set the predetermined coefficient to a large value compared to when the steering wheel angle is small and the forklift F travels almost straight.

[0049] The determination unit 130 may perform a process of determining whether or not the road surface on which the forklift F is traveling is in a state requiring a warning, by using one or a combination of the processes described above.

[0050] The determination unit 130 may determine that the road surface is in a different warning state depending on the magnitude of the difference in the rotation speeds. For example, when the difference in the rotation speeds is small, the determination unit 130 may determine that the road surface is in a "weak" warning state, and when the difference in the rotation speeds is large, the determination unit 130 may determine that the road surface is in a "strong" warning state. For example, the "weak" warning state may mean a state that requires a warning to the user. The "strong" warning state may mean a state that requires a warning to the user and restricts the travel of the forklift F.

[0051] When it is determined that the road surface on which the forklift F is traveling is in a state requiring a warning, the determination unit 130 may output status data indicating the state requiring a warning and the vehicle position of the forklift F in association with each other. The database 15 may store the status data and the vehicle position output from the controller 100 in association with each other.

[0052] The determination unit 130 may also acquire the status data and the vehicle position from the database 15 via the input unit 21. The determination unit 130 may then determine whether or not the distance between the vehicle position associated with the status data and the current vehicle position of the forklift F is equal to or less than a predetermined distance. If the distance is equal to or less than the predetermined distance, the determination unit 130 may determine that the road surface on which the forklift F is traveling is in a state requiring a warning.

[0053] Alternatively, when it is determined that the road surface is in a state requiring a warning, the determination unit 130 may stop control of the fork unit 51 and the backrest unit 52, which are the luggage loading unit. For example, when it is determined that the road surface is in a state requiring a warning, the determination unit 130 may stop the lifting and lowering operation of the fork unit 51.

[0054] When it is determined that the road surface is in a state requiring a warning, the determination unit 130 may stop control of the travel of the forklift F. For example, when it is determined that the road surface is in a state requiring a warning, the determination unit 130 may stop operations of the forklift F that involve changes in the vehicle position and vehicle attitude, such as moving forward, backward, turning right, or turning left.

[0055] [Warning device handling procedure] Next, the processing procedure of the vehicle operation state detection device according to this embodiment will be described with reference to the flowcharts of FIGS.

[0056] 4 and 5 may be started when the ignition of the forklift F is turned on, and may be repeatedly executed while the ignition is on. Furthermore, the process shown in the flowchart of FIG. 4 and the process shown in the flowchart of FIG. 5 may be executed in parallel, or may be executed alternately.

[0057] 4 is a flowchart showing a first example of processing by the warning device according to this embodiment. In step S101, the input unit 21 acquires position information. The position acquisition unit 120 calculates the vehicle position of the forklift F based on the position information.

[0058] In step S103, the input unit 21 acquires the rotation speed information.

[0059] In step S105, the rotation difference calculation unit 115 calculates rotation speed difference information based on the rotation speed information.

[0060] In step S107, the determination unit 130 determines whether the first difference calculated by the rotational difference calculation unit 115 is equal to or greater than the first threshold. If the first difference is equal to or greater than the first threshold (YES in step S107), the determination unit 130 determines in step S107 that the road surface is in a warning state ("one-wheel slippage"). Furthermore, the notification unit 400 notifies the user that the road surface state is "one-wheel slippage". Then, the process proceeds to step S115.

[0061] On the other hand, if the first difference is not equal to or greater than the first threshold (NO in step S107), in step S111, the determination unit 130 determines whether the second difference calculated by the rotation difference calculation unit 115 is equal to or greater than the second threshold.

[0062] If the second difference is equal to or greater than the second threshold value (YES in step S111), in step S113, the determination unit 130 determines that the road surface is in a warning state ("front wheel slippage"). Furthermore, the notification unit 400 notifies the user that the road surface state is "front wheel slippage." Then, the process proceeds to step S115.

[0063] If the second difference is not equal to or greater than the second threshold (NO in step S111), the process of the flowchart in FIG. 4 ends.

[0064] In step S115, the determination unit 130 outputs the status data indicating the warning target status in association with the vehicle position of the forklift F. The database 15 stores the status data and the vehicle position output from the controller 100 in association with each other.

[0065] 5 is a flowchart showing a second example of the processing of the warning device according to this embodiment. In step S201, the input unit 21 acquires position information. The position acquisition unit 120 calculates the current vehicle position of the forklift F based on the position information.

[0066] In step S203, the input unit 21 acquires the status data and the vehicle position associated with the status data.

[0067] In step S205, the determination unit 130 determines whether the distance between the vehicle position associated with the status data and the current vehicle position of the forklift F is equal to or less than a predetermined distance.

[0068] If the distance is less than the predetermined distance (YES in step S205), in step S207, the determination unit 130 determines that the road surface is in a state that requires a warning, as represented by the state data. The notification unit 400 notifies the user that the road surface state is in a state that requires a warning. After that, the processing of the flowchart in FIG. 5 ends.

[0069] If the distance is not equal to or less than the predetermined distance (NO in step S205), the process of the flowchart in FIG. 5 ends.

[0070] [Effects of the embodiment] As described above in detail, the warning device, warning method, and warning program according to this embodiment acquire rotation speed information indicating the rotation speed of each of a plurality of wheels of a vehicle having a cargo loading section, and acquire the vehicle position of the vehicle. Based on the rotation speed information, it is determined whether the road surface on which the vehicle is traveling is in a state requiring a warning, and if it is determined that the road surface is in a state requiring a warning, status data indicating the state requiring a warning is output in association with the vehicle position.

[0071] This allows the risk of a vehicle tipping over to be evaluated at low cost, and an appropriate warning issued to the vehicle user or manager. In particular, if the vehicle's wheels spin when passing over a low-friction road (a road surface with a low coefficient of friction), a step, a slope, etc., a warning can be issued indicating that there is a risk of the vehicle tipping over.

[0072] Furthermore, according to the warning device, warning method, and warning program of this embodiment, the vehicle may have a luggage carrying section in front of the front wheels of the vehicle. The road surface may be determined to be in a warning state when the difference between the rotation speed of the right front wheel of the vehicle and the rotation speed of the left front wheel of the vehicle is equal to or greater than a first threshold. This allows for the detection of "one-wheel skid" on the front wheels, which are more likely to receive load, and for the risk of the vehicle tipping over to be determined. As a result, the accuracy of the determination can be improved.

[0073] Furthermore, according to the warning device, warning method, and warning program of this embodiment, the vehicle may have a luggage carrying section in front of the front wheels of the vehicle. The road surface may be determined to be in a warning state when the difference between the rotation speed of the front wheels and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold. This allows for detection of "front wheel slippage" on the front wheels, which are more likely to receive load, and for determining the risk of the vehicle tipping over. As a result, the accuracy of the determination can be improved.

[0074] Furthermore, the warning device, warning method, and warning program according to the present embodiment may stop control of the luggage carrying unit when it is determined that the vehicle is in a warning state, thereby preventing an increase in the risk of the vehicle tipping over due to the up and down movement of the luggage carrying unit when there is a risk of the vehicle tipping over.

[0075] Furthermore, in the warning device, warning method, and warning program according to the present embodiment, the storage unit may store the status data in association with the vehicle position. This allows locations with a high risk of vehicle tipping over to be newly registered in a database or the like. Furthermore, a manager can check locations with a high risk of vehicle tipping over after the fact, and use the information to help with road surface repair work.

[0076] Furthermore, according to the warning device, warning method, and warning program of this embodiment, a memory unit may store a map of the road surface on which the vehicle is traveling, plotting status data. Furthermore, each time the map is updated by receiving status data and the vehicle position, the updated map may be output. This allows locations with a high risk of the vehicle tipping over to be managed in a database or the like. Furthermore, a manager can check locations with a high risk of the vehicle tipping over after the fact, and use the information to help with road surface repair work.

[0077] Furthermore, according to the warning device, warning method, and warning program of the present embodiment, the notification unit may notify the user when it determines that the road surface is in a state requiring a warning, thereby making it possible to appropriately issue a warning to the user or manager of the vehicle.

[0078] Each function described in the above embodiments may be implemented by one or more processing circuits, including programmed processors, electrical circuits, and even devices such as application specific integrated circuits (ASICs), circuit components arranged to perform the described functions.

[0079] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0080] 1 Warning device 11 Measurement section 15 Database (storage section) 21 Input section 51 Fork section (loading section) 52 Backrest section 53 Mast section 100 Controllers 115 Rotation difference calculation unit 120 Position acquisition part 130 Judgment section 400 Information Department F Forklift (vehicle) TY1 Left front wheel TY2 Right front wheel TY3 left rear wheel TY4 Right rear wheel

Claims

1. an input unit for inputting rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels, and a vehicle position of the vehicle; A controller; A warning device comprising: The controller determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information; When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position; The controller determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information; When it is determined that the difference is equal to or greater than the first threshold, it is determined that the road surface is in the warning state, If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information; When it is determined that the value is equal to or greater than the second threshold, it is determined that the road surface is in the warning state. Warning device.

2. The warning device according to claim 1 , wherein the controller stops control of the luggage carrying section when it is determined that the vehicle is in the warning target state.

3. The warning device according to claim 1 or 2, further comprising a storage unit that stores the status data and the vehicle position in association with each other.

4. 4. The warning device according to claim 3, wherein the storage unit stores a map of the road surface on which the condition data is plotted, and outputs the updated map each time the storage unit receives the condition data and the vehicle position and updates the map.

5. 5. The warning device according to claim 1, further comprising a notification unit that notifies a user when it is determined that the road surface is in the warning state.

6. 1. A computer-implemented alerting method comprising: acquire rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels; Obtaining a vehicle position of the vehicle; determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information; When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position; determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information; When it is determined that the difference is equal to or greater than the first threshold, it is determined that the road surface is in the warning state, If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information; When it is determined that the value is equal to or greater than the second threshold, it is determined that the road surface is in the warning state. Warning method.

7. acquire rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels; Obtaining a vehicle position of the vehicle; determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information; When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position; determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information; When it is determined that the difference is equal to or greater than the first threshold, it is determined that the road surface is in the warning state, If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information; When it is determined that the value is equal to or greater than the second threshold, it is determined that the road surface is in the warning state. A warning program that causes a computer to perform a process.

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