Submergence estimation device for road surface

Abstract

The present invention accurately determines whether a road surface on which a vehicle is located is submerged. A submergence estimation device (2) is applied to a vehicle in which at least one of a plurality of wheels is a drive wheel and at least one of the plurality of wheels is a following wheel, and comprises: a wheel speed difference acquisition unit (200) that acquires a wheel speed difference from a difference between the wheel speed of the drive wheel and the wheel speed of the following wheel; and a submergence determination unit (202) that determines whether the road surface on which the vehicle is located is submerged on the basis of the wheel speed difference.

Description

Road flooding estimation device

[0001] The present disclosure relates to a road surface flooding estimation device.

[0002] Patent Document 1 discloses a flooding data detection program that determines whether water resistance corresponding to flooding is occurring as running resistance based on a comparison between an ideal acceleration calculated from the vehicle's driving force value and running resistance value and the actual value of the vehicle's acceleration, and detects flooding data that indicates the flooded state of the road surface.

[0003] Japanese Patent Application Publication No. 2021-54311

[0004] However, in the flood data detection program described in Patent Document 1, flood-related values ​​related to flooding, such as flood depth, are calculated based on the deviation between the actual vehicle acceleration value and the ideal acceleration, and therefore, unless changes in the vehicle mass due to changes in occupants, etc. are reflected, calculation errors in the flood-related values ​​will be large. One aspect of the present disclosure aims to accurately determine whether the road surface on which a vehicle is located is flooded.

[0005] In order to solve the above problems, a road surface flooding estimation device according to one aspect of the present disclosure is applied to a vehicle in which at least one of a plurality of wheels is a drive wheel and at least one of the plurality of wheels is a driven wheel, and includes: a wheel speed difference acquisition unit that acquires a wheel speed difference from the difference between the wheel speed of the drive wheel and the wheel speed of the driven wheel, and a flooding determination unit that determines whether the road surface on which the vehicle is located is flooded based on the wheel speed difference acquired by the wheel speed difference acquisition unit. The road surface flooding estimation device according to each aspect of the present disclosure may be realized by a computer, and in this case, a control program for the flooding estimation device that causes a computer to operate as each unit (software element) of the flooding estimation device to realize the flooding estimation device on a computer, and a computer-readable recording medium on which the control program is recorded, also fall within the scope of the present disclosure.

[0006] According to one aspect of the present disclosure, it is possible to accurately determine whether the road surface on which a vehicle is located is submerged.

[0007] Fig. 1 is a configuration diagram of a flood estimation system including a road surface flood estimation device according to embodiment 1 of the present disclosure. Fig. 2 is a diagram showing an example configuration of a flood estimation device according to embodiment 1 of the present disclosure. Fig. 3 is a diagram used to explain estimation of flood depth by a flood determination unit. Fig. 4 is a flowchart showing the flow of flood determination processing in the flood estimation device according to embodiment 1 of the present disclosure. Fig. 5 is a state transition diagram showing the entry status of a vehicle into a flooded road, as determined by a flood estimation device according to embodiment 2 of the present disclosure.

[0008] [Embodiment 1] (Configuration of a road surface flooding estimation device) Fig. 1 is a configuration diagram of a flooding estimation system that includes a road surface flooding estimation device according to embodiment 1 of the present disclosure. The flooding estimation system 1 shown in Fig. 1 is a system that estimates roads whose road surfaces are flooded (hereinafter referred to as flooded roads), and includes a flooding estimation device 2 and a server 3. Here, road surface flooding refers to a state in which the road surface is covered with water.

[0009] The flood estimation system 1 includes one or more flood estimation devices 2. In Fig. 1, a plurality of flood estimation devices 2 are disposed on each vehicle V. The vehicle V is, for example, a four-wheel, front-wheel drive vehicle in which the left and right front wheels are drive wheels and the left and right rear wheels are driven wheels. The flood estimation device 2 determines whether the road surface on which the vehicle V on which it is disposed is located is flooded.

[0010] The server 3 is located outside the flood estimation device 2. For example, the server 3 is a cloud server located outside the vehicle V equipped with the flood estimation device 2. The server 3 can send and receive information to and from the flood estimation device 2. For example, the server 3 receives, from a plurality of flood estimation devices 2, determination results that the road surface on which the vehicle V is located is flooded, and estimates a flooded road based on that information.

[0011] 2 is a diagram illustrating an example configuration of a flood estimation device according to embodiment 1 of the present disclosure. The flood estimation device 2 illustrated in FIG. 2 includes a control unit 20, a storage unit 21, an input / output interface 22, an operation amount detection unit 23, a traveling state detection unit 24, and a display unit 25.

[0012] The control unit 20 is, for example, a CPU (Central Processing Unit). The control unit 20 reads and executes programs from the memory unit 21. The memory unit 21 has a storage medium such as a hard disk drive (HDD) or a solid state drive (SSD). The memory unit 21 stores the programs executed by the control unit 20 and vehicle specifications of the vehicle V. Possible vehicle specifications of the vehicle V include information about the drive system of the vehicle V, information about the braking system of the vehicle V, information about the steering system of the vehicle V, information about the weight of the vehicle V, information about the dimensions of the vehicle V, information about the tires of the vehicle V, and the friction coefficient. The memory unit 21 also has a temporary storage medium such as a RAM (Random Access Memory) that the control unit 20 uses as a workspace.

[0013] The input / output interface 22 is, for example, a USB (Universal Serial Bus) terminal or a LAN (Local Area Network) terminal. The flooding estimation device 2 is connected to a vehicle communication network such as a CAN (Controller Area Network) via the input / output interface 22, and the flooding estimation device 2 can send and receive information to and from the server 3 via the CAN. The operation amount detection unit 23 detects the operation amount of an operation member of the vehicle V. Possible operation members of the vehicle V include an accelerator pedal, a brake pedal, and a steering wheel. The driving condition detection unit 24 detects the driving condition of the vehicle V. The driving condition of the vehicle V includes at least the wheel speeds of the drive wheels and driven wheels of the vehicle V. The driving condition of the vehicle V may include position information of the vehicle V, the speed of the vehicle V, acceleration in three directions (forward / backward, left / right, and up / down), angular velocities in three directions (pitch, yaw, and roll) of the vehicle V, and master cylinder pressure. The display unit 25 is, for example, a liquid crystal display device, and displays a setting screen for the flooding estimation device 2, a screen that provides the user with information about flooding of roads, and the like.

[0014] The control unit 20 of the flooding estimation device 2 shown in Figure 2 executes a program stored in the memory unit 21, and thereby functions as a wheel speed difference acquisition unit 200, a running resistance acquisition unit 201, a flooding determination unit 202, and a determination result output unit 203.

[0015] The wheel speed difference acquisition unit 200 acquires the wheel speed difference from the difference between the wheel speed of the driving wheels of the vehicle V detected by the traveling condition detection unit 24 and the wheel speed of the driven wheels of the vehicle V. The wheel speed difference is calculated, for example, by the following formula (1): Wheel speed difference = (wheel speed of left driving wheel - wheel speed of left driven wheel) / wheel speed of left driving wheel + (wheel speed of right driving wheel - wheel speed of right driven wheel) / wheel speed of right driving wheel ... (1)

[0016] The running resistance acquisition unit 201 acquires the running resistance value acting on the vehicle V. The running resistance value includes friction resistance, gradient resistance, air resistance, and water resistance acting on the vehicle V. The running resistance value is calculated based on information such as the amount of operation of the operating member of the vehicle V detected by the operation amount detection unit 23, the running state of the vehicle V detected by the running state detection unit 24, and the friction coefficient stored in the memory unit 21 as vehicle specifications of the vehicle V.

[0017] The submergence determination unit 202 determines whether the road surface on which the vehicle V is located is submerged, based on the wheel speed difference obtained by the wheel speed difference acquisition unit 200 and the running resistance value obtained by the running resistance acquisition unit 201. For example, the submergence determination unit 202 calculates a submergence estimate value using the following equation (2): Submergence estimate value = Running resistance value × Wheel speed difference / Vehicle speed (2) Here, the vehicle speed is estimated based on the operation amount of the operating member of the vehicle V detected by the operation amount detection unit 23 and the running state of the vehicle V detected by the running state detection unit 24.

[0018] The estimated flooding value calculated by equation (2) represents an estimate of the mass flow rate of water flowing on the road surface on which the vehicle V is located. The flooding determination unit 202 determines the depth of water covering the road surface on which the vehicle V is located (hereinafter referred to as flood depth) based on the estimated flooding value. For example, if the estimated flooding value is less than a first threshold, the flooding determination unit 202 determines that the road surface on which the vehicle V is located is not flooded. If the estimated flooding value is equal to or greater than a predetermined first threshold, the flooding determination unit 202 determines that the road surface on which the vehicle V is located is flooded. The first threshold is a value that is set in advance based on vehicle specifications such as the tire diameter of the vehicle V.

[0019] When the submergence determiner 202 determines that the road surface on which the vehicle V is located is submerged, it may estimate the submergence depth. Estimation of submergence depth by the submergence determiner 202 will be described using FIG. 3. FIG. 3 is a diagram showing an example of changes in the submergence estimate value when the vehicle travels along a route that includes a submerged road, and an example of the submergence depth estimation result by the submergence determiner. The horizontal axis of graph G shown in FIG. 3 is the distance L that the vehicle V has traveled on the route from the start position of the route. The vertical axis of graph G represents the submergence estimate value calculated at a position where the vehicle V has traveled the distance L along the route from the start position. Below graph G in FIG. 3, the submergence depth estimation result by the submergence determiner 202 at a position where the vehicle V has traveled the distance L along the route from the start position is shown.

[0020] For example, if the estimated submergence value is equal to or greater than the first threshold and less than the second threshold, the submergence determiner 202 estimates the submergence depth to be "less than 100 mm." As described above, the first threshold is a threshold used by the submergence determiner 202 when determining whether the road surface on which the vehicle V is located is submerged. The second threshold is set to a value greater than the first threshold. In FIG. 3 , when the distance traveled by the vehicle V from the start position is equal to or greater than L1 and less than L2, and greater than L5 and less than L6, the estimated submergence value is equal to or greater than the first threshold and less than the second threshold, and the submergence depth estimated by the submergence determiner 202 is "less than 100 mm."

[0021] For example, when the estimated submergence value is equal to or greater than the second threshold and less than the third threshold, the submergence determiner 202 estimates the submergence depth as "100 mm or greater but less than 200 mm." The third threshold is set to a value greater than the second threshold. In FIG. 3 , when the distance traveled by the vehicle V from the start position is equal to or greater than L2 but less than L3, or greater than L4 but less than L5, the estimated submergence value is equal to or greater than the second threshold and less than the third threshold, and the submergence depth estimated by the submergence determiner 202 is "100 mm or greater but less than 200 mm."

[0022] For example, if the estimated submergence value is equal to or greater than the third threshold, submergence determiner 202 estimates the submergence depth to be "200 mm or greater." In Figure 3, when the distance traveled by vehicle V from the start position is between L3 and L4, the estimated submergence value is equal to or greater than the third threshold, and the submergence depth estimation result by submergence determiner 202 is "200 mm or greater." The method of estimating submergence depth by submergence determiner 202 shown in Figure 3 is one example and is not limited to this.

[0023] The determination result output unit 203 outputs the result of the determination made by the submergence determination unit 202 to the display unit 25 and the server 3. For example, the determination result output unit 203 displays information including at least the estimated submergence value calculated by the submergence determination unit 202 or the submergence depth estimated by the submergence determination unit 202 on the display unit 25, and notifies the occupants that the road surface around the vehicle V is submerged. In addition, the determination result output unit 203 transmits at least one of the estimated submergence value and the submergence depth, and the position information of the vehicle V detected by the traveling condition detection unit 24 to the server 3.

[0024] The server 3 shown in FIG. 1 receives information from the determination result output unit 203 of the submergence estimation device 2. For example, the server 3 receives at least one of a submergence estimate value and a submergence depth, and location information of the vehicle V, from the determination result output unit 203 of the submergence estimation device 2. The server 3 estimates the submergence status of the road network based on the information received from multiple submergence estimation devices 2. The submergence status of the road network includes, for example, the submergence depth of each road included in the road network. The server 3 transmits information about the estimated submergence status of the road network to the submergence estimation device 2. The submergence estimation device 2 displays a screen based on the information about the submergence status received from the server 3. For example, the submergence estimation device 2 displays information about a flooded road on the display unit 25, urging the occupant of the vehicle V to avoid entering a flooded road, or presenting the occupant with a route to escape from the flooded road.

[0025] Figure 4 is a flowchart showing the flow of submergence determination processing in the submergence estimation device according to the first embodiment of the present disclosure. The series of processing steps shown in Figure 4 are repeatedly executed by the control unit 20 of the submergence estimation device 2. Once the control unit 20 of the submergence estimation device 2 has finished the processing shown in Figure 4, it starts the processing for the next cycle.

[0026] 4, the control unit 20 functions as the wheel speed difference acquisition unit 200 and acquires the wheel speed difference of the vehicle V. Subsequently, in S110, the control unit 20 functions as the running resistance acquisition unit 201 and acquires the running resistance value acting on the vehicle V. Note that the processing of S110 may be executed before S100, or the processing of S100 and S110 may be executed simultaneously.

[0027] At S120, the control unit 20 functions as the submergence determination unit 202 and acquires a submergence estimate. For example, the control unit 20 acquires a submergence estimate by calculating Equation (2) based on the wheel speed difference of the vehicle V acquired at S100 and the running resistance value of the vehicle V acquired at S110 (S120). At S130, the control unit 20 functions as the submergence determination unit 202 and determines whether the submergence estimate acquired at S120 is equal to or greater than a first threshold. If the submergence estimate is equal to or greater than the first threshold (S130: YES), the control unit 20 estimates the submergence depth based on the submergence estimate (S140). At S150, the control unit 20 functions as the determination result output unit 203 and transmits at least one of the submergence estimate acquired at S120 and the submergence depth estimated at S140, as well as the position information of the vehicle V detected by the traveling condition detection unit 24, to the display unit 25 and the server 3. If the estimated flooding value obtained in S120 is less than the first threshold, the control unit 20 determines that the road surface on which the vehicle V is located is not flooded (S130: NO), ends the processing of the current cycle, and starts the processing of the next cycle.

[0028] [Embodiment 2] Embodiment 2 of the present disclosure will be described below. For ease of explanation, members having the same functions as those described in embodiment 1 will be denoted by the same reference numerals, and their description will not be repeated.

[0029] The flooding estimation device 2 in embodiment 2 differs from embodiment 1 in that the flooding determination unit 202 determines whether the road surface on which the vehicle V is located is flooded or not based on the wheel speed difference acquired by the wheel speed difference acquisition unit 200 and the running resistance value acquired by the running resistance acquisition unit 201, as well as the amount of change in the flooding estimation value.

[0030] 5 is a state transition diagram showing a state of a vehicle entering a flooded road, determined by a flood estimation device according to embodiment 2 of the present disclosure. The state transition diagram shown in FIG. 5 includes a first state ST1, a second state ST2, a third state ST3, and a fourth state ST4.

[0031] (First state ST1: Outside flooded road) The first state ST1 indicates a state in which the road surface on which the vehicle V is located is not flooded. When the vehicle V is in the first state ST1 and the vehicle V satisfies all of the following first entry conditions [1-1] to [1-4], the entry state of the vehicle V into the flooded road transitions to the second state ST2. [1-1] The brake pedal is not depressed. [1-2] The estimated vehicle speed of the vehicle V is equal to or greater than a predetermined first speed. [1-3] The running resistance value is equal to or greater than a predetermined value. [1-4] As a result of repeatedly obtaining a flooding estimate, the flooding estimate value has increased a predetermined number of times in succession.

[0032] The running resistance value also increases due to braking control associated with operation of the brake pedal of the vehicle V. The first entry condition [1-1] is to assume that an increase in the running resistance value when the brake pedal of the vehicle V is operated is due to braking control, and not due to an increase in water resistance caused by flooding of the road surface.

[0033] In the first approach condition [1-2], the first speed is, for example, 5 km / h, a speed at which it has been confirmed through experiments that there is no significant difference in running resistance value inside and outside the flooded road. In the first approach condition [1-3], the predetermined value is a value set in advance through experiments or the like, and is a value greater than the running resistance value when the vehicle V is outside the flooded road. In the first approach condition [1-4], the predetermined number of times is, for example, three times.

[0034] (Second State ST2: Entry) The second state ST2 indicates a state in which the vehicle V has entered a flooded road from outside the flooded road. When the entry status of the vehicle V into the flooded road is in the second state ST2, if the following second entry condition [2-1] or [2-2] is met, the entry status of the vehicle V into the flooded road transitions to the third state ST3. [2-1] All of the above first entry conditions [1-1] to [1-3] are met. [2-2] The escape condition [3-1] described below is met, but the escape condition [3-2] is not met.

[0035] Furthermore, when the vehicle V is in the second state ST2 and the following escape conditions [3-1] and [3-2] are all met, the vehicle V transitions to the fourth state ST4: [3-1] At least one of the first entry conditions [1-1] to [1-3] is not met; [3-2] The estimated flooding value is repeatedly acquired, and as a result, the estimated flooding value decreases a predetermined number of times in succession. Here, the predetermined number is, for example, two times.

[0036] (Third State ST3: Inside Flooded Road) The third state ST3 indicates a state in which the vehicle V continues to travel inside a flooded road. When the vehicle V is in the third state ST3 and the above-described escape conditions [3-1] and [3-2] are all satisfied, the vehicle V's entry status into the flooded road transitions to a fourth state ST4.

[0037] (Fourth state ST4: Exit) The fourth state ST4 indicates a state in which the vehicle V has exited the flooded road. When the entry status of the vehicle V into the flooded road is in the fourth state ST4, the state transitions to the first state ST1.

[0038] [Modification] In the above embodiment, the flood estimation system 1 is provided with the server 3, but it is not necessary to provide the server 3. Direct communication may be performed between a plurality of flood estimation devices 2, and at least one of the determination result of the flood determination unit 202 and the flood estimation value, and the position information of the vehicle V detected by the traveling condition detection unit 24 may be transmitted and received between them.

[0039] In the above embodiment, the submergence determination process shown in FIG. 4 is executed by the control unit 20 of the submergence estimation device 2. However, part of the submergence determination process shown in FIG. 4 may be executed by the server 3. For example, the control unit 20 of the submergence estimation device 2 may transmit the wheel speeds of the drive wheels and the driven wheels of the vehicle V detected by the running condition detection unit 24 to the server 3, causing the server 3 to calculate a wheel speed difference (S100). The control unit 20 of the submergence estimation device 2 may transmit information such as the operation amount of the operating member of the vehicle V detected by the operation amount detection unit 23 and the running condition of the vehicle V detected by the running condition detection unit 24 to the server 3, causing the server 3 to calculate a running resistance value (S110). The server 3 may also function as the submergence determination unit 202. For example, the server 3 may obtain a submergence estimation value based on the wheel speed difference and running resistance value calculated by the control unit 20 of the submergence estimation device 2 or the server 3 (S120). The control unit 20 of the submergence estimation device 2 or the server 3 may determine whether the acquired submergence estimate value is equal to or greater than a first threshold value (S130), and the submergence depth may be estimated based on the submergence estimate value (S140). The submergence depth estimated by the server 3 may be transmitted from the server 3 to the submergence estimation device 2, and information including at least the submergence depth may be displayed on the display unit 25 of the submergence estimation device 2.

[0040] In the above embodiment, the estimated flooding value acquired by the flooding determination unit 202 is an estimate of the mass flow rate of water flowing on the road surface on which the vehicle V is located. However, the estimated flooding value is not limited to the mass flow rate of water as long as it is a physical quantity related to water covering the road surface. For example, the estimated flooding value may be the volumetric flow rate of water flowing on the road surface on which the vehicle V is located, or the depth of water covering the road surface on which the vehicle V is located. Furthermore, the estimated flooding value may be a physical quantity that can be calculated without using the running resistance value acquired by the running resistance acquisition unit 201. For example, the estimated flooding value may be a constant multiple of the result of dividing the wheel speed difference by the vehicle speed.

[0041] In the above embodiment, the wheel speed difference is calculated based on the above formula (1), but the formula for calculating the wheel speed difference is not limited to the above formula (1). For example, the wheel speed difference may be calculated using the following formula (3): Wheel speed difference = (average value of wheel speeds of left and right driving wheels - average value of wheel speeds of left and right driven wheels) / average value of wheel speeds of left and right driving wheels (3)

[0042] In the above embodiment, the vehicle V is a front-wheel drive vehicle in which the left and right front wheels are drive wheels and the left and right rear wheels are driven wheels, but is not limited to this. The vehicle V may be any vehicle that has at least one drive wheel and at least one driven wheel, and may be, for example, a two-wheel vehicle in which the front wheel is a driven wheel and the rear wheel is a drive wheel, a three-wheel vehicle in which one front wheel is a drive wheel and the two rear wheels (left and right) are driven wheels, or a four-wheel rear-wheel drive vehicle in which the left and right rear wheels are drive wheels and the left and right front wheels are driven wheels. When the vehicle V is a two-wheel vehicle, the wheel speed difference may be calculated, for example, using the following formula (4): Wheel speed difference = (wheel speed of drive wheel - wheel speed of driven wheel) / wheel speed of drive wheel ... (4)

[0043] The first entry conditions [1-1] to [1-4] described in the second embodiment are not limited to those described above. For example, the first entry condition [1-2] may include a condition that the estimated vehicle speed of the vehicle V is equal to or less than a second speed. The second speed is a value at which the influence of air resistance on the running resistance value is equal to or greater than a predetermined percentage, such as 40 km / h. When entering a flooded road, occupants of the vehicle V often do not increase the speed of the vehicle V compared to when traveling on a road that is not flooded. Therefore, even if the first entry condition [1-2] includes a condition that the estimated vehicle speed of the vehicle V is equal to or less than the second speed, it is possible to properly determine whether the vehicle has entered a flooded road.

[0044] In the second embodiment described above, when the entry status of the vehicle V into the flooded road is in the second state ST2 and all of the escape conditions [3-1] and [3-2] are satisfied, the entry status of the vehicle V into the flooded road transitions to the fourth state ST4. However, when the entry status of the vehicle V into the flooded road is in the second state ST2, the entry status of the vehicle V into the flooded road may transition to the third state without depending on the second condition, rather than directly transitioning to the fourth state ST4.

[0045] [Example of Software Implementation] The functions of the flood estimation device 2 (hereinafter referred to as the "device") can be realized by a program that causes a computer to function as the device, and that causes the computer to function as each control block of the device (particularly each unit included in the control unit 20). In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The functions described in each of the above embodiments are realized by executing the program using the control device and storage device. The program may be stored non-transitory on one or more computer-readable storage media. The storage media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium. Furthermore, some or all of the functions of each control block may be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each control block is formed is also within the scope of the present disclosure. Alternatively, the functions of each control block may be realized by, for example, a quantum computer. Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0046] [Summary] A road surface flooding estimation device according to one aspect of the present disclosure is applied to a vehicle in which at least one of a plurality of wheels is a drive wheel and at least one of the plurality of wheels is a driven wheel, and includes: a wheel speed difference acquisition unit that acquires a wheel speed difference from the difference between the wheel speeds of the drive wheels and the drive wheels; and a flooding determination unit that determines whether the road surface on which the vehicle is located is flooded based on the wheel speed difference acquired by the wheel speed difference acquisition unit. The present disclosure determines whether the road surface on which the vehicle is located is flooded based on the wheel speed difference, which is the difference between the wheel speeds of the drive wheels and the drive wheels. The wheel speed difference used for this determination is not affected by changes in the mass of the vehicle due to changes in occupants, etc. Therefore, whether the road surface is flooded can be accurately determined even if the mass of the vehicle changes.

[0047] A road surface flooding estimation device according to one aspect of the present disclosure includes a running resistance acquisition unit that acquires a running resistance value acting on the vehicle, and the flooding determination unit determines whether the road surface on which the vehicle is located is flooded based on the wheel speed difference acquired by the wheel speed difference acquisition unit and the running resistance value acquired by the running resistance acquisition unit. In a first embodiment, the flooding determination unit determines whether the road surface on which the vehicle is located is flooded based on a flooding estimate value calculated based on the wheel speed difference and the running resistance value (S130). In a second embodiment, the road surface on which the vehicle is located is determined to be flooded based on a change in the flooding estimate value (first entry condition [1-4]). When a vehicle is traveling on a flooded road, the running resistance value increases due to an increase in water resistance. By determining whether the road surface on which the vehicle is located is flooded by taking the running resistance value into account, a more accurate determination can be achieved.

[0048] A flood estimation device according to one aspect of the present disclosure includes a running resistance acquisition unit that acquires a running resistance value acting on the vehicle, and the flood determination unit estimates the flood depth of the road surface on which the vehicle is located based on the wheel speed difference acquired by the wheel speed difference acquisition unit and the running resistance value acquired by the running resistance acquisition unit. In the above embodiment, a flood estimation value, which is an estimate of the mass flow rate of water flowing on the road surface on which the vehicle V is located, is calculated based on the wheel speed difference acquired by the wheel speed difference acquisition unit 200 and the running resistance value acquired by the running resistance acquisition unit 201, and the flood depth of the road surface on which the vehicle is located is estimated based on the flood estimation value. As the flood depth of the road surface on which the vehicle V is located increases, the water resistance acting on the vehicle increases. Because the wheel speed of the driven wheels is more susceptible to water resistance than the wheel speed of the drive wheels, the wheel speed difference increases as the flood depth increases. Estimating the flood depth based on the flood estimation value, which is based on the wheel speed difference and the running resistance value, enables accurate estimation of the flood depth.

[0049] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0050] 2 Flooding estimation device 20 Control unit 21 Memory unit 200 Wheel speed difference acquisition unit 201 Running resistance acquisition unit 202 Flooding determination unit 203 Determination result output unit

Claims

1. A road surface flooding estimation device applied to a vehicle in which at least one of a plurality of wheels is a drive wheel and at least one of the plurality of wheels is a driven wheel, comprising: a wheel speed difference acquisition unit that acquires a wheel speed difference from the difference between the wheel speed of the drive wheel and the wheel speed of the driven wheel; and a flooding determination unit that determines whether the road surface on which the vehicle is located is flooded or not based on the wheel speed difference acquired by the wheel speed difference acquisition unit.

2. A road surface flooding estimation device as described in claim 1, further comprising a running resistance acquisition unit that acquires a running resistance value acting on the vehicle, and the flooding determination unit determines whether or not the road surface on which the vehicle is located is flooded based on the wheel speed difference acquired by the wheel speed difference acquisition unit and the running resistance value acquired by the running resistance acquisition unit.

3. A road surface flooding estimation device as described in claim 1, further comprising a running resistance acquisition unit that acquires a running resistance value acting on the vehicle, and the flooding determination unit estimates the flooding depth of the road surface on which the vehicle is located based on the wheel speed difference acquired by the wheel speed difference acquisition unit and the running resistance value acquired by the running resistance acquisition unit.

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