Vehicle control device

Abstract

A control unit provided in a vehicle control device according to the present invention comprises: a slip vibration detection unit that detects slip vibration of a drive wheel; an estimated road surface friction coefficient calculation unit that obtains an estimated road surface friction coefficient on the basis of the slip vibration; a comparison unit that compares the estimated road surface friction coefficient with a slip notification threshold value; and an output unit that outputs a notification command signal to a notification unit when the comparison unit determines that the estimated road surface friction coefficient is less than or equal to the slip notification threshold value. The control unit further includes a slip notification threshold value setting unit that variably sets the slip notification threshold value according to the road shape recognized on the basis of the travel environment information.

Description

Vehicle control device

[0001] The present invention relates to a vehicle control device.

[0002] A vehicle will slip when the driving force applied to the tires of its drive wheels (referred to as "drive tires") exceeds the grip force from the road surface acting on the drive tires (referred to as "road grip force"). As shown in Figure 7, the driving force P of the drive tires (front wheels in the figure) of vehicle M can be calculated by the following equation: P = T / r (1) where T is the torque of the drive tires and r is the effective radius of the drive tires.

[0003] The road grip force F is calculated as follows: F=μ·Wf (2) where μ is the road friction coefficient, Wf is the vehicle weight applied to the driving tires (front wheels), and in FIG. 7, W is the total vehicle weight, and Wr is the vehicle weight applied to the driven tires (rear wheels).

[0004] When traveling on a road with low road surface μ, such as a snowy or frozen road, F<P, making it easier for the drive wheels to slip.

[0005] For example, Japanese Patent Application Laid-Open Publication No. 2013-112192 discloses a technology in which, when vehicle slippage is detected from the difference between the rotational speed of the drive wheels and the rotational speed of the driven wheels, a reaction force control device applies a reaction force to the accelerator pedal to notify the driver that a slippage has occurred.

[0006] When driving on a low-μ road such as a snowy road, the driver is often aware of the conditions under which slippage will occur. However, the technology disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2013-112192 uniformly detects the occurrence of slippage and causes the reaction force control device to apply a reaction force to the accelerator pedal.

[0007] Therefore, the driver may feel that the reaction force on the accelerator pedal is coming earlier than expected, or the driver may feel that the reaction force on the accelerator pedal is unnecessary.

[0008] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a vehicle control device that can vary the timing of informing the driver of the possibility of slippage in accordance with the driver's sensibility.

[0009] One aspect of the present invention includes a driving environment information acquisition unit that acquires driving environment information ahead of the vehicle, a notification unit that notifies the driver of the possibility of slippage, and a control unit, wherein the control unit includes a slip vibration detection unit that detects slip vibration of a drive wheel, an estimated road surface friction coefficient calculation unit that calculates an estimated road surface friction coefficient based on the slip vibration detected by the slip vibration detection unit, a comparison unit that compares the estimated road surface friction coefficient calculated by the estimated road surface friction coefficient calculation unit with a slip alert threshold, and an output unit that outputs a notification command signal to the notification unit when the comparison unit determines that the estimated road surface friction coefficient is equal to or less than the slip alert threshold, and the control unit further includes a slip alert threshold setting unit that variably sets the slip alert threshold in accordance with the road shape recognized based on the driving environment information acquired by the driving environment information acquisition unit.

[0010] One aspect of the present invention includes a driving environment information acquisition unit that acquires driving environment information ahead of the vehicle, a notification unit that alerts the driver of the possibility of slippage, and a control unit, wherein the control unit includes a slip vibration detection unit that detects slip vibration of a drive wheel, an estimated road surface friction coefficient calculation unit that calculates an estimated road surface friction coefficient based on the slip vibration detected by the slip vibration detection unit, a corrected road surface friction coefficient calculation unit that calculates a corrected road surface friction coefficient by correcting the estimated road surface friction coefficient calculated by the estimated road surface friction coefficient calculation unit with a correction coefficient set in accordance with a road shape recognized based on the driving environment information acquired by the driving environment information acquisition unit, a comparison unit that compares the corrected road surface friction coefficient set by the corrected road surface friction coefficient calculation unit with a slip alert threshold value, and an output unit that outputs an alert command signal to the notification unit when the comparison unit determines that the estimated road surface friction coefficient is equal to or less than the slip alert threshold value.

[0011] Schematic diagram of a control device mounted on an electric vehicle. Flowchart showing a slip notification control routine (part 1). Flowchart showing a slip notification control routine (part 2). Explanatory diagram showing driving control when traveling on a curved road with no oncoming vehicles. Explanatory diagram showing driving control when traveling on a curved road with an approaching oncoming vehicle. Explanatory diagram showing driving control when traveling on a curved road with a narrow road width. Flowchart showing a slip notification control routine according to another embodiment. Explanatory diagram showing the relationship between the driving force of the drive tires and the road surface grip force.

[0012] An embodiment of the present invention will be described below with reference to the drawings. Note that the drawings are schematic, and the relationship between the thickness and width of each member, the thickness ratio of each member, etc., differ from the actual ones. Of course, the drawings also include portions in which the dimensional relationships and ratios differ from one another.

[0013] 1, reference numeral 1 denotes a drive control device. The drive control device 1 is mounted on a host vehicle M (see FIG. 7). The host vehicle M is an electric vehicle. Hereinafter, the host vehicle M will be referred to as an electric vehicle M in the following description.

[0014] The drive control device 1 has a vehicle integrated control unit 2 as a control section. This vehicle integrated control unit 2 comprehensively performs various controls related to the drive of the electric vehicle M. A camera control unit 3 is connected to the input side of this vehicle integrated control unit 2. Although not shown, various sensors that acquire information required when driving the electric vehicle M are also connected to the vehicle integrated control unit 2.

[0015] Furthermore, a vibration sensor 14a is connected to the input side of the vehicle integrated control unit 2. The vibration sensor 14a detects vibrations (hereinafter referred to as "motor vibrations") [Hz] that occur at the rotational speed of a drive motor 14, which will be described later.

[0016] An inverter control unit 5 and a pressure actuator 8 serving as a notification unit are connected to the output side of the vehicle integrated control unit 2. Although not shown, the vehicle integrated control unit 2 is connected to various control units so as to be able to communicate bidirectionally.

[0017] Each control unit 2, 3, 5 is composed of a microcontroller equipped with a CPU, RAM, ROM, rewritable non-volatile memory (flash memory or EEPROM), and peripheral devices. The ROM stores programs and fixed data necessary for the CPU to execute various processes. The RAM serves as a work area for the CPU, temporarily storing various data for the CPU. The CPU is also called an MPU (microprocessor) or processor. A GPU (graphics processing unit) or a GSP (graph streaming processor) may be used instead of the CPU. Alternatively, a CPU, GPU, and GSP may be selectively combined.

[0018] An inverter 12 of an electric powertrain 11 is connected to the inverter control unit 5. The electric powertrain 11 includes the inverter 12, a high-voltage battery 13, and a drive motor 14. The inverter 12 is operated by a command signal from the inverter control unit 5. In accordance with the command signal from the inverter control unit 5, the inverter 12 converts direct current (DC) power from the high-voltage battery 13 into alternating current (AC) power and supplies it to the drive motor 14. The inverter control unit 5 controls the driving force of the drive motor 14 by vector control.

[0019] An output shaft 21 of the drive motor 14 is connected to drive shafts 22l, 22r of left and right drive wheels Fl, Fr via a differential Df. The drive motor 14 drives the drive wheels Fl, Fr with power supplied from the inverter 12, thereby powering the electric vehicle M.

[0020] Reference numeral 31 denotes a pedal operation unit. This pedal operation unit 31 is operated by the driver and has an accelerator pedal 31a for setting the vehicle speed and a brake pedal 31b. A pressure actuator 8 is connected to the accelerator pedal 31a and the brake pedal 31b. This pressure actuator 8 applies a reaction force to the accelerator pedal 31a and the brake pedal 31b in accordance with a command from the vehicle integrated control unit 2.

[0021] A camera unit 6 is installed at the front of the electric vehicle M. The camera unit 6 is equipped with a stereo camera consisting of a main camera 6a and a sub-camera 6b. The camera control unit 3 acquires information about the driving environment ahead of the electric vehicle M by processing the images of the driving environment ahead of the electric vehicle M captured by both cameras 6a and 6b. Therefore, the camera control unit 3 functions as a driving environment information acquisition unit of the present invention.

[0022] The acquired forward driving environment information includes the road shape (straight road, curved road) ahead of the electric vehicle M, a preceding vehicle, an oncoming vehicle traveling in the oncoming lane, and the like.

[0023] A navigation system 7 is also connected to the camera control unit 3. The navigation system 7 has a storage unit that stores road map information. The navigation system 7 acquires vehicle position information (latitude, longitude, and altitude) that is information about the current position of the electric vehicle M based on GNSS (Global Navigation Satellite System) satellites.

[0024] The navigation system 7 then plots the acquired vehicle position on the road map information stored in the storage unit, and estimates the current vehicle position on the road map and the traveling direction.

[0025] Furthermore, the navigation system 7 acquires environmental information about the current vehicle position based on road map information, and outputs this environmental information to the vehicle integrated control unit 2 via the camera control unit 3. Therefore, the navigation system 7 also has the function of the driving environment information acquisition unit of the present invention.

[0026] The environmental information acquired by the navigation system 7 includes road shapes such as straight roads and curved roads.

[0027] When the vehicle integrated control unit 2 detects the possibility of slippage of the drive wheels Fl and Fr, it operates the pressure actuator 8 to apply a reaction force to the accelerator pedal 31a and the brake pedal 31b, thereby informing the driver that slippage has occurred.

[0028] However, for example, when driving on a curved road with low μ, the driver may think that if they drive slightly wider than the center of the lane, the side slip will be reduced, the driving will be stable, and they will be able to continue driving. In this embodiment, the threshold value for notifying the possibility of slippage is changed depending on the road shape and the presence or absence of oncoming vehicles.

[0029] Specifically, the slip notification control executed by the vehicle integrated control unit 2 is performed in accordance with a slip notification control routine shown in FIGS. 2A and 2B.

[0030] The vehicle integrated control unit 2 reads the motor vibration [Hz] detected by the vibration sensor 14a (step S1). This vibration sensor 14a detects the vibration [Hz] occurring in the rotation speed of the drive motor 14. Then, based on the motor vibration [Hz] detected by the vibration sensor 14a, the vehicle integrated control unit 2 checks whether or not slip vibration is occurring in the drive motor 14 (step S2). The processing in steps S1 and S2 corresponds to the slip vibration detection unit of the present invention.

[0031] When a sudden torque fluctuation occurs in the drive motor 14, vibration occurs in the rotation speed of the drive motor 14. When the drive wheels Fl and Fr spin (slip), high-frequency motor vibration occurs in the rotation speed of the drive motor 14.

[0032] If the motor vibration is equal to or greater than the set frequency, the vehicle integrated control unit 2 determines that slip vibration is present (step S2: YES). If the motor vibration is less than the set frequency, the vehicle integrated control unit 2 determines that slip vibration is absent (step S2: NO). If it determines that slip vibration is absent (step S22: NO), the routine is terminated.

[0033] When the vehicle integrated control unit 2 determines that slip vibration is present (step S22: YES), it calculates an estimated road friction coefficient (estimated road surface μ) from the slip vibration (step S3). The process in step S3 corresponds to the estimated road friction coefficient calculation unit of the present invention.

[0034] Next, the vehicle integrated control unit 2 acquires information on the road surface shape (straight road, curved road, road width, etc.) ahead of the electric vehicle M (step S4). This road surface shape is acquired from road map information based on the vehicle position acquired by the navigation system 7. Alternatively, this road shape information is acquired from information on the driving environment ahead of the electric vehicle M recognized by the camera control unit 3.

[0035] The vehicle integrated control unit 2 also acquires oncoming vehicle information indicating whether an oncoming vehicle O (see FIG. 4) is approaching in the oncoming lane (step S5). This oncoming vehicle information is acquired from information about the driving environment ahead of the electric vehicle M recognized by the camera control unit 3. Alternatively, this oncoming vehicle information is acquired through vehicle-to-vehicle communication with the oncoming vehicle O.

[0036] Then, the vehicle integrated control unit 2 checks whether the road ahead is a curved road based on the road shape information acquired in step S4 (step S6). If the road ahead is a curved road, the process proceeds to step S7. If the road ahead is a straight road, the process proceeds to step S10.

[0037] The vehicle integrated control unit 2 checks whether an oncoming vehicle O is approaching based on the oncoming vehicle information acquired in step S5 (step S7). If it determines that an oncoming vehicle O has not been detected, the process proceeds to step S8. If it determines that the approach of an oncoming vehicle O has been detected, the process proceeds to step S9. In step S8, the vehicle integrated control unit 2 compares the road width Rw with a preset narrow road determination threshold Wo based on road shape information acquired by the navigation system 7 or the camera control unit 3. If the vehicle integrated control unit 2 determines that Rw > Wo, the process proceeds to step S11. If the vehicle integrated control unit 2 determines that Rw ≦ Wo, the process proceeds to step S12.

[0038] On the other hand, the vehicle integrated control unit 2 compares the road width Rw with a preset narrow road determination threshold Wo (step S9). If the vehicle integrated control unit 2 determines that Rw > Wo, the process proceeds to step S13. If the vehicle integrated control unit 2 determines that Rw ≤ Wo, the process proceeds to step S14.

[0039] The vehicle integrated control unit 2 sets the slip notification threshold μt to a first initial value A (e.g., μ = 0.1) (step S10), and proceeds to step S15. The slip notification threshold μt set in step S10 is set assuming driving on a straight road.

[0040] The vehicle integrated control unit 2 also sets the slip notification threshold μt to a second initial value B (e.g., μ = 0.3) (step S11), and proceeds to step S15. The slip notification threshold μt set in step S11 is set assuming driving on a curved road.

[0041] Furthermore, the vehicle integrated control unit 2 sets the slip notification threshold μt to a third initial value C (e.g., μ = 0.5) (step S12), and proceeds to step S15. The slip notification threshold μt set in step S12 is set assuming a curved road with a narrow road width.

[0042] The vehicle integrated control unit 2 also sets the slip notification threshold μt to a fourth initial value D (e.g., μ = 0.7) (step S13), and proceeds to step S15. The slip notification threshold μt set in step S13 is set assuming a curvy road on which an oncoming vehicle O is approaching.

[0043] Furthermore, the vehicle integrated control unit 2 sets the slip notification threshold μt to a fifth initial value E (e.g., μ=0.9) (step S14), and proceeds to step S15. The slip notification threshold μt set in step S14 is set assuming a curved road with an oncoming vehicle O approaching and a narrow road width. The processing in steps S10 to S14 corresponds to the slip notification threshold setting unit of the present invention.

[0044] The above-mentioned initial values ​​A to E are set according to the driver's sensitivity when driving the electric vehicle M (A<B<C<D<E). That is, the slip notification threshold μt when traveling on a straight road is set to the first initial value A, which has the lowest road surface μ. For example, if the road surface μ of this first initial value A is 0.1, a determination of NO will be made in step S15, which will be described later, on a road where μ<0.1. Therefore, a reaction force application command signal will not be output from the vehicle integrated control unit 2. As a result, the frequency of unnecessary reaction force application will decrease, and the discomfort felt by the driver can be alleviated.

[0045] 5, when the vehicle is traveling on a curved road, an oncoming vehicle O is approaching, and the road width Rw is narrow (Rw≦Wo), the fifth initial value E having the highest road surface μ is set in step S14. For example, if the road surface μ of this fifth initial value E is 0.9, and the vehicle is traveling on a road where μ≧0.9, a YES determination is made in step S15, which will be described later.

[0046] Therefore, the reaction force application command signal is output more frequently from the vehicle integrated control unit 2, and the vehicle integrated control unit 2 can notify the driver of the possibility of slippage at an early stage. As a result, it is possible to prevent the electric vehicle M from drifting toward the oncoming lane when passing an oncoming vehicle O, as shown by the dashed line in Figure 5.

[0047] 3, even if the road is curved, if an oncoming vehicle O is not approaching and the road width Rw is relatively wide (Rw>Wo), the slip notification threshold μt is set to a second initial value B higher than the first initial value A (step S11). Therefore, even if the electric vehicle M deviates slightly from the target traveling path indicated by the solid line, as shown by the dashed line in FIG. 3, the vehicle integrated control unit 2 will not output a reaction force application command signal. As a result, the vehicle integrated control unit 2 can notify the driver of the possibility of slippage at a timing that is generally in line with the driver's sensibility.

[0048] In contrast, when the road is curved, no oncoming vehicle O is approaching, and the road width is relatively narrow (Rw≦Wo), in step S12 the slip warning threshold μt is set to a third initial value C that is higher than the second initial value B. Therefore, assuming that no oncoming vehicle O is approaching in FIG. 5, the vehicle integrated control unit 2 will not output a reaction force application command signal until the vehicle diverges further toward the oncoming lane than the bulge indicated by the dashed line in the figure. Therefore, even in this case, the vehicle integrated control unit 2 can warn of the possibility of slippage at a timing that is generally in line with the driver's sensibility.

[0049] 4, even if the road width Rw is relatively wide (Rw>Wo) on a curved road, if an oncoming vehicle O is approaching, the slip warning threshold μt is set to a fourth initial value D higher than the third initial value C in step S13. Therefore, as shown by the dashed line in FIG. 4, if there is a possibility that the electric vehicle M will drift toward the oncoming lane, a reaction force application command signal is output early from the vehicle integrated control unit 2. As a result, it is possible to improve safety when the driver drives the electric vehicle M along a curved road.

[0050] Thereafter, the vehicle integrated control unit 2 compares the estimated road surface μ with the slip notification threshold μt (step S15). The process in step S15 corresponds to the comparison section of the present invention.

[0051] If μ≦μt (YES), the vehicle integrated control unit 2 determines that there is a possibility of slippage, and proceeds to step S16, whereas if μ>μt (NO), the routine is terminated.

[0052] In step S16, the vehicle integrated control unit 2 outputs a reaction force application command signal to the pressure actuator 8 to generate a reaction force, and then exits the routine.

[0053] The pressure actuator 8 outputs a pressure command value to the accelerator pedal 31 a and the brake pedal 31 b in accordance with a pressure application command signal from the vehicle integrated control unit 2. This pressure command value is a force that repels the pressure applied when the driver depresses either the accelerator pedal 31 a or the brake pedal.

[0054] The reaction force command value may simply apply a repulsive force to the accelerator pedal 31 a and the brake pedal 31 b. Alternatively, the reaction force command value may generate vibrations in the accelerator pedal 31 a and the brake pedal 31 b. Furthermore, the reaction force command value may simultaneously or alternately apply a repulsive force and vibrations to the accelerator pedal 31 a and the brake pedal 31 b.

[0055] The driver can recognize the possibility of slippage of the drive wheels Fl and Fr by feeling the reaction force received when depressing either the accelerator pedal 31a or the brake pedal 31b.

[0056] In this way, in this embodiment, the slip warning threshold μt is variably set depending on the road shape and the presence or absence of an oncoming vehicle O. Therefore, the timing of warning of the possibility of slippage can be set to suit the driver's sensitivity. As a result, the frequency of unnecessary reaction forces being applied to the accelerator pedal 31a and the brake pedal 31b is reduced, and the discomfort felt by the driver can be alleviated.

[0057] Furthermore, when the vehicle is traveling on a curved road, an oncoming vehicle O is approaching, and the road width Rw is narrow (Rw≦Wo), the slip warning threshold μt is set to a relatively high road surface μ. Therefore, the vehicle integrated control unit 2 can warn the driver of the possibility of slippage at an early stage. As a result, safety when traveling on a curved road can be further improved.

[0058] [Other Aspects] Figure 6 shows another aspect of the slip suppression control routine shown in Figure 2B. In the routine shown in Figure 2B, the slip notification threshold μt is set depending on the road shape and the presence or absence of an oncoming vehicle O. In contrast, in the slip suppression control routine shown in Figure 6, the slip notification threshold μt is set to a constant value, and the estimated road surface μ is multiplied by a gain set depending on the road shape and the presence or absence of an oncoming vehicle O to set the compensated road surface μs to be compared.

[0059] Steps S1 to S9 are the same as those in the flowcharts shown in FIGS. 2A and 2B, and therefore a description thereof will be omitted.

[0060] If the vehicle integrated control unit 2 determines in step S6 that the road is a straight road (NO), it corrects the estimated road surface μ by the first gain α to set a corrected road surface μs (step S21: μs←α·μ). If the vehicle integrated control unit 2 determines in step S8 that Rw>Wo (NO), it corrects the estimated road surface μ by the second gain β to set a corrected road surface μs (step S22: μs←β·μ).

[0061] Furthermore, if the vehicle integrated control unit 2 determines that the road is a curved road (step S6: YES), it corrects the estimated road surface μ by the first gain α to set a corrected road surface μs (step S21: μs←α·μ). If the vehicle integrated control unit 2 determines that Rw>Wo (step S8: NO), it corrects the estimated road surface μ by the second gain β to set a corrected road surface μs (step S22: μs←β·μ). If the vehicle integrated control unit 2 determines that Rw≦Wo (step S8: YES), it corrects the estimated road surface μ by the third gain γ to set a corrected road surface μs (step S23: μs←γ·μ).

[0062] Furthermore, if the vehicle integrated control unit 2 determines that Rw>Wo (step S9: NO), it corrects the estimated road surface μ by the fourth gain δ to set a corrected road surface μs (step S24: μs←δ·μ). Furthermore, if the vehicle integrated control unit 2 determines that Rw≦Wo (step S9: YES), it corrects the estimated road surface μ by the fifth gain ε to set a corrected road surface μs (step S25: μs←ε·μ). The processing in steps S21 to S26 corresponds to the corrected road surface friction coefficient calculation unit of the present invention.

[0063] Then, the vehicle integrated control unit 2 compares the corrected road surface μs with the slip notification threshold μt (step S26). The process in step S26 corresponds to the comparison section of the present invention.

[0064] The slip notification threshold μt is a fixed value (e.g., μt = 0.9) set to reduce unnecessary slip notifications and, when necessary, to notify the driver of the possibility of slippage early. The first to fifth gains α, β, γ, δ, and ε are set to vary the timing of notifying the driver of the possibility of slippage in accordance with the driver's sensitivity. These gains have the following relationship: α > β > γ > δ > ε. For example, α = 1.9, β = 1.7, γ = 1.5, δ = 1.3, and ε = 1.1.

[0065] If the vehicle integrated control unit 2 determines that μs≦μt (step S26: YES), it determines that there is a possibility of slippage, and proceeds to step S16. On the other hand, if it determines that μs > μt (step S26: NO), it exits the routine. In step S16, the vehicle integrated control unit 2 outputs a reaction force application command signal to the pressure actuator 8 to generate a reaction force, and then exits the routine. The processing in step S16 corresponds to the output section of the present invention.

[0066] When the estimated road surface μ is constant, the corrected road surface μs set on a straight road is a value obtained by correcting the estimated road surface μ with the largest first gain α. As a result, the frequency of μs > μt increases, making it possible to reduce unnecessary slip warnings from the vehicle integrated control unit 2. On the other hand, when an approaching oncoming vehicle O is detected on a curved road and the road width is relatively narrow (Rw≦Wo), the estimated road surface μ is corrected with the smallest fifth gain ε, and the corrected road surface μs is set. Therefore, when μs≦μt, the driver can be warned of the possibility of slippage at an early stage.

[0067] In this way, the same effect as in the above-described embodiment can be obtained by setting the slip notification threshold μt to a constant value, multiplying the estimated road surface μ by a gain that is set depending on the road shape and the presence or absence of an oncoming vehicle O, and comparing the corrected road surface μs to be compared with the slip notification threshold μt.

[0068] The electric vehicle M may be a four-wheel drive vehicle. In addition, although the curved road on which the electric vehicle M travels is shown as an inner loop in the figure, the curved road on which the electric vehicle M travels may also be an outer loop.

[0069] Furthermore, the means for informing the driver of the possibility of slippage is not limited to reaction forces applied to the accelerator pedal 31a and the brake pedal 31b, but may also be a display on a monitor or an audio notification from a speaker.

Claims

1. A vehicle control device comprising: a driving environment information acquisition unit that acquires driving environment information ahead of the vehicle; a notification unit that alerts the driver of the possibility of slippage; and a control unit, wherein the control unit comprises: a slip vibration detection unit that detects slip vibration of a drive wheel; an estimated road surface friction coefficient calculation unit that calculates an estimated road surface friction coefficient based on the slip vibration detected by the slip vibration detection unit; a comparison unit that compares the estimated road surface friction coefficient calculated by the estimated road surface friction coefficient calculation unit with a slip alert threshold value; and an output unit that outputs an alert command signal to the notification unit when the comparison unit determines that the estimated road surface friction coefficient is equal to or lower than the slip alert threshold value, and the control unit further comprises a slip alert threshold value setting unit that variably sets the slip alert threshold value in accordance with a road shape recognized based on the driving environment information acquired by the driving environment information acquisition unit.

2. A vehicle control device as described in claim 1, characterized in that when the driving environment information acquired by the driving environment information acquisition unit recognizes that the road shape is a straight road, the slip warning threshold setting unit sets the slip warning threshold at a lower friction coefficient than when the driving environment information acquired by the driving environment information acquisition unit recognizes that the road shape is a curved road.

3. A vehicle control device as described in claim 2, characterized in that when the driving environment information acquired by the driving environment information acquisition unit recognizes that the road shape is a curved road and that an oncoming vehicle is approaching, the slip warning threshold setting unit sets the slip warning threshold at a higher friction coefficient than when only a curved road is recognized.

4. A vehicle control device comprising: a driving environment information acquisition unit which acquires driving environment information ahead of the vehicle; a notification unit which notifies the occurrence of a possibility of slippage; and a control unit, wherein the control unit comprises: a slip vibration detection unit which detects slip vibration of a drive wheel; an estimated road surface friction coefficient calculation unit which calculates an estimated road surface friction coefficient based on the slip vibration detected by the slip vibration detection unit; a corrected road surface friction coefficient calculation unit which calculates a corrected road surface friction coefficient by correcting the estimated road surface friction coefficient calculated by the estimated road surface friction coefficient calculation unit with a correction coefficient set according to a road shape recognized based on the driving environment information acquired by the driving environment information acquisition unit; a comparison unit which compares the corrected road surface friction coefficient set by the corrected road surface friction coefficient calculation unit with a slip notification threshold value; and an output unit which outputs a notification command signal to the notification unit when the comparison unit determines that the estimated road surface friction coefficient is equal to or lower than the slip notification threshold value.

5. A vehicle control device as described in claim 4, characterized in that when the driving environment information acquired by the driving environment information acquisition unit recognizes that the road shape is a straight road, the corrected road friction coefficient calculation unit corrects the estimated road friction coefficient with a higher correction coefficient than when the driving environment information acquired by the driving environment information acquisition unit recognizes that the road shape is a curved road.

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