Vehicle control method and vehicle control device

Abstract

To accurately determine whether a wheel is slipped.SOLUTION: When it is determined that a vehicle travels on a bad road by bad road determination processing, slip determination processing of determining whether the vehicle is slipped is ended or execution of the slip determination processing is inhibited. When it is determined that the vehicle is slipped, the vehicle lowers output of a driving source. The slip determination processing determines that the vehicle is slipped, when wheel acceleration exceeds a predetermined positive slip determination threshold for a predetermined slip determination time. The bad road determination processing determines that the vehicle travels on the bad road, when the vehicle acceleration is lower than a predetermined negative bad road determination threshold.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vehicle control method and a vehicle control device. [Background technology]

[0002] For example, Patent Document 1 discloses that when the wheel acceleration exceeds a predetermined slip detection threshold, it is determined that the wheels are slipping. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-283591 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, when the vehicle is traveling on a road surface where the wheel acceleration varies greatly, i.e., a rough road, there is a risk that the wheel acceleration may exceed the slip detection threshold even when the wheels are not slipping. Therefore, in Patent Document 1, when the vehicle is traveling on a rough road, it may be erroneously determined that the wheels are slipping, and torque down and deceleration may occur that are not intended by the driver.

[0005] In other words, there is room for further improvement in determining whether or not the wheels of a vehicle are slipping, so as to prevent erroneous slip determinations from being made. [Means for solving the problem]

[0006] The vehicle of the present invention performs a rough road judgment process to determine whether or not the vehicle is traveling on a rough road, and when it is determined by the rough road judgment process that the vehicle is traveling on a rough road, the slip judgment process to determine whether or not the vehicle is slipping is terminated or the execution of the slip judgment process is prohibited, and when it is determined that the vehicle is slipping, the output of the vehicle's drive source is reduced.

[0007] The slip determination process determines that the vehicle is slipping when the wheel acceleration exceeds a predetermined positive slip determination threshold value for a predetermined slip determination time.

[0008] The rough road determination process determines that the vehicle is traveling on a rough road when the wheel acceleration falls below a predetermined negative rough road determination threshold value. Effect of the Invention

[0009] According to the present invention, by performing a rough road judgment process, it is possible to accurately judge whether or not the wheels are slipping, and it is possible to avoid unintended torque down or deceleration of the vehicle caused by momentary fluctuations in wheel acceleration. [Brief description of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram that illustrates an outline of a drive system of a vehicle to which the present invention is applied; [Diagram 2] 5 is a timing chart showing an example of the behavior of various parameters during slip determination processing. [Diagram 3] 5 is a timing chart showing an example of the behavior of various parameters during slip determination processing. [Figure 4] 5 is a timing chart showing an example of the behavior of various parameters during a rough road determination process. [Diagram 5] 5 is a flowchart showing the flow of a rough road determination process. [Figure 6] 3 is a flowchart showing a flow of control of a vehicle to which the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0012] FIG. 1 is an explanatory diagram that shows a schematic overview of a drive system of a vehicle 1 to which the present invention is applied.

[0013] The vehicle 1 is an electric vehicle using a motor as a drive source, or a hybrid vehicle (series hybrid vehicle) in which an internal combustion engine is installed for generating electricity and the motor is used to power the drive wheels.

[0014] The vehicle 1 is a four-wheel drive vehicle in which all wheels 2 are driven wheels, and has a first drive unit 3 that drives the left and right front wheels 2a via a first differential gear 4, and a second drive unit 5 that drives the left and right rear wheels 2b via a second differential gear 6.

[0015] The first drive unit 3 has a first drive motor (not shown) that serves as a drive source for the left and right front wheels 2a, and a first reduction gear unit (not shown) that reduces the rotation of the first drive motor and transmits it to the front wheels. The first drive motor is a drive source for the vehicle 1.

[0016] The second drive unit 5 has a second drive motor (not shown) that serves as a drive source for the left and right rear wheels 2b, and a second reduction gear unit (not shown) that reduces the rotation of the second drive motor and transmits it to the rear wheels. The second drive motor is a drive source for the vehicle 1.

[0017] The first drive unit 3 and the second drive unit 5 are supplied with power from a battery 7. The battery 7 may be charged with, for example, power generated by a power generation unit (not shown).

[0018] The power supplied to the first drive unit 3 and the second drive unit 5 is controlled by the control unit 8. That is, the motor drive forces of the first drive motor and the second drive motor are controlled by the control unit 8.

[0019] The control unit 8 is a well-known digital computer equipped with a CPU, ROM, RAM and an input / output interface.

[0020] The control unit 8 receives detection signals from various sensors, such as an accelerator opening sensor 9 that detects the amount of depression (accelerator opening) of an accelerator pedal (not shown) of the vehicle 1, a vehicle speed sensor 10 that detects the vehicle speed of the vehicle 1, an acceleration sensor 11 that detects the acceleration in the longitudinal direction of the vehicle 1, and a plurality of wheel speed sensors 12 that are provided for each wheel 2 of the vehicle 1 and detect the wheel speed. The control unit 8 is capable of calculating the wheel acceleration using the wheel speed detected by the wheel speed sensor 12. The wheel acceleration is calculated, for example, by differentiating the wheel speed. Furthermore, the wheel acceleration is a differentiated value of the wheel speed, and its rise (change) is faster than the wheel speed.

[0021] Here, the control unit 8 performs a rough road determination process to determine whether or not the vehicle 1 is traveling on a rough road, and a slip determination process to determine whether or not the wheels 2 of the vehicle 1 are slipping. Furthermore, when it is determined that the wheels 2 of the vehicle 1 are slipping, the control unit 8 performs a predetermined torque down control to reduce the output of the drive source of the slipping wheels 2.

[0022] In other words, the control unit 8 corresponds to a bad road judgment processing execution section, a slip judgment processing execution section, and an output control section.

[0023] The rough road determination process is performed when the vehicle 1 is accelerating. In the rough road determination process, for example, when the wheel acceleration of any wheel of the vehicle 1 falls below a predetermined negative rough road determination threshold, it is determined that the vehicle 1 is traveling on a rough road. The rough road determination threshold is a value obtained by subtracting from the wheel acceleration the absolute value of an offset amount (difference) between a second wheel slip threshold Ts2 (described later) and the wheel acceleration.

[0024] The control unit 8 determines that the vehicle is accelerating when the driving force of the vehicle 1 is greater than the estimated running resistance. The running resistance of the vehicle 1 is calculated, when the wheels 2 are gripping, using, for example, the acceleration of the vehicle 1, the total torque of the driving wheels (total torque of the four wheels), and the weight of the vehicle 1. Whether or not the wheels 2 are gripping is determined from the wheel acceleration and a slip determination threshold value, which will be described later. The torque of the driving wheels is calculated, for example, using the accelerator opening, vehicle speed, etc.

[0025] When it is determined by the rough road determination process that the vehicle 1 is traveling on a rough road, the determination that the vehicle 1 is traveling on a rough road is maintained until, for example, the wheel acceleration of all the wheels 2 exceeds the rough road determination release threshold continuously for a predetermined rough road determination release time (fixed time) or more. The rough road determination release threshold is a predetermined value that is greater than the rough road determination threshold, for example, "0". In other words, the determination that the vehicle 1 is traveling on a rough road is released if the wheel acceleration continues to be positive.

[0026] The slip determination process is performed for each wheel 2 of the vehicle 1, i.e., for each drive wheel of the vehicle 1. In the slip determination process, the vehicle 1 is determined to be slipping when the wheel acceleration of at least one of the drive wheels 2 exceeds a predetermined positive slip determination threshold continuously for a predetermined slip determination time. For example, when the control unit 8 determines that the right front wheel 2a, which is a drive wheel, has slipped, it determines that a slip has occurred at the front of the vehicle 1. Furthermore, when the control unit 8 determines that the right front wheel 2a and the left rear wheel 2b, which are drive wheels, have slipped, it determines that a slip has occurred at the front and rear of the vehicle 1.

[0027] The slip determination process can be carried out simultaneously with the rough road determination process, but if it is determined that the vehicle 1 is traveling on a rough road, the process is terminated if it is in progress, and is prohibited from being carried out if it is not in progress until it is determined that the vehicle 1 is not traveling on a rough road.

[0028] The slip judgment threshold is set according to the driving force of the motor (driving force commanded to the motor), which is the torque of the drive wheels. For example, the slip judgment threshold for the front wheels 2a is set according to the driving force of the first drive motor (driving force commanded to the first drive motor). The slip judgment threshold for the rear wheels 2b is set according to the driving force of the second drive motor (driving force commanded to the second drive motor). Specifically, a map that associates the slip judgment threshold with the driving force of the motor is set in advance, and the slip judgment threshold is calculated from this map and the driving force of the motor. In other words, the slip judgment threshold changes according to the driving force of the motor.

[0029] The slip determination thresholds are a first wheel slip threshold Ts1 that is set so as not to be exceeded by wheel acceleration occurring during acceleration of the vehicle 1, and a second wheel slip threshold Ts2 that is greater than the first wheel slip threshold Ts1. The second wheel slip threshold Ts2 is a value that will not be exceeded by fluctuations in wheel acceleration during driving if the vehicle is not slipping.

[0030] The length of the slip determination time is set longer in the slip determination process using the first wheel slip threshold Ts1 than in the slip determination process using the second wheel slip threshold Ts2.

[0031] The torque down control reduces the torque of a motor (for example, the first drive motor or the second drive motor) that serves as the drive source for the slipping drive wheel.

[0032] The torque down control ends when the wheel acceleration remains at or above "0" (zero or greater) for a preset period of time. That is, the control unit 8 starts counting up the grip count when the wheel acceleration becomes at or above "0" while the torque down control is being performed, and ends the torque down control when the grip count becomes at or above a preset third count threshold.

[0033] For example, if it is determined that the front wheels 2a and rear wheels 2b are both slipping, the vehicle 1 will terminate the torque down control for the first drive motor when the slip of the front wheels 2a is resolved, but if the slip of the rear wheels 2b has not been resolved at this time, the vehicle 1 will continue the torque down control for the second drive motor.

[0034] 2 and 3 are timing charts showing an example of the behavior of various parameters during slip determination processing for one of the four wheels 2 (drive wheels) of the vehicle 1. In FIG.

[0035] The example shown in FIG. 2 shows a case where the vehicle 1 is determined to be slipping because the wheel acceleration of the corresponding wheel 2 exceeds a first wheel slip threshold value Ts1.

[0036] Time t1 in Fig. 2 is the timing when the wheel acceleration exceeds the first wheel slip threshold Ts1, and is also the timing when the first slip count starts to count up. The first slip count continues to count up while the wheel acceleration exceeds the first wheel slip threshold Ts1. When the wheel acceleration becomes equal to or less than the first wheel slip threshold Ts1, the first slip count stops counting up and is reset (set to zero).

[0037] Time t2 in FIG. 2 is the timing when the first slip count becomes equal to or greater than the first count threshold. That is, time t2 in FIG. 2 is the timing when a predetermined slip determination time has elapsed since the wheel acceleration became greater than the first wheel slip threshold Ts1. In other words, the time from time t1 to time t2 in FIG. 2 is the slip determination time of the slip determination process using the first wheel slip threshold Ts1. The slip flag, which indicates whether the vehicle 1 is slipping or not, switches from "0" to "1" at time t2 in FIG. 2. The slip flag becomes "0" when it is determined that the vehicle 1 is not slipping, and becomes "1" when it is determined that the vehicle 1 is slipping. Note that from time t2 in FIG. 2, torque down control is implemented to reduce the driving force transmitted to the slipping wheel 2. The four-wheel total torque, which is the sum of the torque of the front wheels 2a and the rear wheels 2b (total of the drive wheels), decreases from time t2 in Figure 2 as the torque of the wheel 2 determined to be slipping is suppressed with the start of torque down control.

[0038] 2, the wheel acceleration becomes equal to or lower than the first wheel slip threshold Ts1, and the first slip count ends at time t3. Note that the first slip count may end at the time t2 when the first slip count becomes equal to or higher than the first count threshold.

[0039] Time t4 in FIG. 2 is the timing when the wheel acceleration becomes constant.

[0040] Time t5 in Fig. 2 is the timing when the slip flag switches from "1" to "0". In the example in Fig. 2, it is determined that the vehicle 1 is no longer slipping at the timing of time t5, and the torque down control ends. With the end of the torque down control, the drive torque of the wheels 2, which had been suppressed until then, returns to normal, and the four-wheel total torque increases from the timing of time t5 in Fig. 2.

[0041] The example shown in FIG. 3 illustrates a case where the wheel acceleration of the corresponding wheel 2 exceeds the second wheel slip threshold value Ts2, and therefore it is determined that the vehicle 1 is slipping.

[0042] Time t1 in Fig. 3 is the timing when the wheel acceleration exceeds the second wheel slip threshold Ts2, and is also the timing when the second slip count starts to count up. The second slip count continues to count up while the wheel acceleration exceeds the second wheel slip threshold Ts2. When the wheel acceleration becomes equal to or less than the second wheel slip threshold Ts2, the second slip count stops counting up and is reset (set to zero).

[0043] Time t2 in FIG. 3 is the timing when the second slip count becomes equal to or greater than the second count threshold. That is, time t2 in FIG. 3 is the timing when a predetermined slip determination time has elapsed since the wheel acceleration became greater than the second wheel slip threshold Ts2. In other words, the time from time t1 to time t2 in FIG. 3 is the slip determination time of the slip determination process using the second wheel slip threshold Ts2. The slip flag, which indicates whether the vehicle 1 is slipping or not, switches from "0" to "1" at the timing of time t2 in FIG. 3. The slip flag becomes "0" when it is determined that the vehicle 1 is not slipping, and becomes "1" when it is determined that the vehicle 1 is slipping. Note that from the timing of time t2 in FIG. 3, torque down control is implemented to reduce the driving force transmitted to the slipping wheel 2. The four-wheel total torque decreases from the timing of time t2 in FIG. 3 because the torque of the wheel 2 determined to be slipping is suppressed with the start of the torque down control.

[0044] 3, the wheel acceleration becomes equal to or lower than the second wheel slip threshold Ts2, and the second slip count ends at time t3. Note that the second slip count may end at the time t2 when the second slip count becomes equal to or higher than the second count threshold.

[0045] Time t4 in FIG. 3 is the timing when the wheel acceleration becomes constant.

[0046] Time t5 in Fig. 3 is the timing when the slip flag switches from "1" to "0". In the example in Fig. 3, it is determined that the vehicle 1 is no longer slipping at the timing of time t5, and the torque down control ends. With the end of the torque down control, the drive torque of the wheels 2, which had been suppressed until then, returns to normal, and the four-wheel total torque increases from the timing of time t5 in Fig. 3.

[0047] FIG. 4 is a timing chart showing an example of the behavior of various parameters during the rough road determination process.

[0048] 4 is the timing at which the wheel acceleration exceeds the second wheel slip threshold Ts2. The second slip count starts to count up from the timing of time t1 in FIG.

[0049] Time t2 in Fig. 4 is the timing when the wheel acceleration becomes equal to or less than the rough road determination threshold. The rough road determination flag switches from "0" to "1" at time t2 in Fig. 4. Also, the second slip count stops counting up and is reset at time t2 in Fig. 4.

[0050] Time t3 in Fig. 4 is the timing when a preset predetermined time has elapsed since the wheel acceleration became equal to or greater than the rough road determination release threshold value. The rough road determination flag switches from "1" to "0" at time t3 in Fig. 4.

[0051] FIG. 5 is a flowchart showing the flow of the rough road determination process in the above-described embodiment.

[0052] In step S1, it is determined whether or not the vehicle 1 is accelerating. If it is determined in step S1 that the vehicle 1 is accelerating, the process proceeds to step S2. If it is determined in step S1 that the vehicle 1 is not accelerating, the process proceeds to step S3. Note that in step S1, it is also possible to determine whether or not the vehicle 1 is accelerating using, for example, the detection value of the acceleration sensor 11.

[0053] In step S2, it is determined whether or not the current bad road flag is 1. If the bad road flag is 1 in step S2, the process proceeds to step S9. If the bad road flag is not 1 in step S2, the process proceeds to step S4.

[0054] In step S3, the bad road flag is set to "0" and the process proceeds to step S8.

[0055] In step S4, a rough road determination threshold is calculated, and the process proceeds to step S5.

[0056] In step S5, it is determined whether the wheel acceleration is below the rough road judgment threshold. If it is determined in step S5 that the wheel acceleration is below the rough road judgment threshold, the process proceeds to step S6. If it is determined in step S5 that the wheel acceleration is not below the rough road judgment threshold, the process proceeds to step S7.

[0057] In step S6, the bad road flag is set to "1" and the process proceeds to step S8.

[0058] In step S7, the bad road flag is set to "0" and the process proceeds to step S8.

[0059] In step S8, it is determined whether the current bad road flag is 1. If the bad road flag is 1 in step S8, the process proceeds to step S9. If the bad road flag is not 1 in step S8, the current routine is terminated.

[0060] In step S9, it is determined whether the wheel acceleration is equal to or greater than the rough road determination release threshold. If it is determined in step S9 that the wheel acceleration is equal to or greater than the rough road determination release threshold, the process proceeds to step S10. If it is determined in step S9 that the wheel acceleration is less than the rough road determination release threshold, the process proceeds to step S11.

[0061] In step S10, the rough road cancellation count is incremented by one, and the process proceeds to step S12.

[0062] In step S11, the rough road cancellation count is cleared (set to zero), and the current routine is terminated.

[0063] In step S12, it is determined whether the bad road count is equal to or greater than the bad road cancellation count threshold. If it is determined in step S12 that the bad road count is equal to or greater than the bad road cancellation count threshold, the process proceeds to step S13. If it is determined in step S12 that the bad road count is less than the bad road cancellation count threshold, the current routine is terminated. The time required for the bad road cancellation count to repeatedly count up and reach the bad road cancellation count threshold is the bad road judgment cancellation time.

[0064] FIG. 6 is a flowchart showing the flow of control of the vehicle 1 in the above-described embodiment.

[0065] In step S21, a bad road flag is calculated by the bad road determination process as shown in FIG.

[0066] In step S22, it is determined whether or not the bad road flag is 1. If the bad road flag is 1 in step S22, the process proceeds to step S23. If the bad road flag is not 1 in step S22, the process proceeds to step S24.

[0067] In step S23, the slip flag is set to "0", and if a first slip count, a second slip count, and a grip count (described later) are being counted, these counts are cleared (set to zero), and the current routine is terminated.

[0068] In step S24, it is determined whether or not the vehicle 1 is decelerating. If it is determined in step S24 that the vehicle 1 is decelerating, the process proceeds to step S23. If it is determined in step S24 that the vehicle 1 is not decelerating, the process proceeds to step S25.

[0069] In step S25, it is determined whether or not the current slip flag is 1. If the slip flag is 1 in step S25, the process proceeds to step S36. If the slip flag is not 1 in step S25, the process proceeds to step S26.

[0070] In step S26, it is determined whether the wheel acceleration is greater than the second wheel slip threshold Ts2. If the wheel acceleration is greater than the second wheel slip threshold Ts2 in step S26, the process proceeds to step S27. If the wheel acceleration is equal to or less than the second wheel slip threshold Ts2 in step S26, the process proceeds to step S28.

[0071] In step S27, the second slip count is incremented by one, and the process proceeds to step S29.

[0072] In step S28, the second slip count is cleared (set to zero), and the process proceeds to step S30.

[0073] In step S29, it is determined whether the second slip count is equal to or greater than the second count threshold. If in step S29 the second slip count is equal to or greater than the second count threshold, the process proceeds to step S34. If in step S29 the second slip count is less than the second count threshold, the process proceeds to step S30. The time required for the second slip count to repeatedly count up and reach the second count threshold is the slip determination time of the slip determination process using the second wheel slip threshold Ts2.

[0074] In step S30, it is determined whether the wheel acceleration is greater than the first wheel slip threshold Ts1. If the wheel acceleration is greater than the first wheel slip threshold Ts1 in step S30, the process proceeds to step S31. If the wheel acceleration is equal to or less than the first wheel slip threshold Ts1 in step S30, the process proceeds to step S32.

[0075] In step S31, the first slip count is incremented by one, and the process proceeds to step S33.

[0076] In step S32, the first slip count is cleared (set to zero), and the process proceeds to step S35.

[0077] In step S33, it is determined whether the first slip count is equal to or greater than the first count threshold. If in step S33 the first slip count is equal to or greater than the first count threshold, the process proceeds to step S34. If in step S33 the first slip count is less than the first count threshold, the process proceeds to step S35. The time required for the first slip count to repeatedly count up and reach the first count threshold is the slip determination time of the slip determination process using the first wheel slip threshold Ts1.

[0078] In step S34, the slip flag is set to "1", and the process proceeds to step S35.

[0079] In step S35, it is determined whether the current slip flag is 1. If the slip flag is 1 in step S35, the process proceeds to step S36. If the slip flag is not 1 in step S35, the current routine is terminated.

[0080] In step S36, the torque down control is carried out, and ends when the slip determination flag becomes "0".

[0081] In step S37, it is determined whether the wheel acceleration is equal to or greater than 0. If the wheel acceleration is equal to or greater than 0 in step S37, the process proceeds to step S38. If the wheel acceleration is less than 0 in step S37, the process proceeds to step S39.

[0082] In step S38, the grip count is incremented by one, and the process proceeds to step S40.

[0083] In step S39, the grip count is cleared (set to zero), and the current routine is terminated.

[0084] In step S40, it is determined whether the grip count is equal to or greater than a third count threshold. If the grip count is equal to or greater than the third count threshold in step S40, the process proceeds to step S41. If the grip count is less than the third count threshold in step S40, the current routine is terminated.

[0085] In step S41, the slip flag is set to "0", the grip count is cleared (set to zero), and the current routine is terminated.

[0086] The vehicle 1 of the above-described embodiment performs the rough road determination process so as not to perform the slip determination process when there is an instantaneous change in wheel acceleration, for example, when passing over a step. In other words, by performing the rough road determination process, the vehicle 1 can accurately determine whether or not the wheel 2 is slipping. Therefore, it is possible to avoid torque down or deceleration of the vehicle unintended by the driver when there is an instantaneous change in wheel acceleration.

[0087] Furthermore, since the vehicle 1 determines slippage of the wheels 2 using the wheel acceleration, it is possible to determine whether or not the wheels 2 are slipping even in a situation where it is difficult to estimate the vehicle speed, such as when all four wheels are spinning.

[0088] By using the wheel acceleration to determine whether the wheel 2 is slipping, the vehicle 1 is able to determine whether the wheel 2 is slipping more quickly than by using the wheel speed.

[0089] The rough road determination threshold is calculated using a second wheel slip threshold Ts2 that is set according to the driving force of the motor. That is, the rough road determination threshold is appropriately set according to the driving force of the motor, so that the vehicle 1 can accurately avoid the slip determination process of the wheel 2 on a rough road while preventing erroneous determination.

[0090] Since the vehicle 1 performs the bad road determination process when accelerating, it is possible to prevent the vehicle 1 from performing the bad road determination process unintentionally when the wheel acceleration decreases due to deceleration.

[0091] When it is determined that the vehicle 1 is traveling on a rough road, the determination that the vehicle 1 is traveling on a rough road is maintained until the wheel acceleration exceeds the rough road determination cancellation threshold continuously for at least the rough road determination cancellation time.

[0092] Therefore, even if the wheel acceleration of the vehicle 1 momentarily falls below the rough road judgment threshold due to a rut or step while the vehicle 1 is traveling on a road surface with low frictional resistance (low μ road), the judgment that the vehicle is traveling on a rough road can be canceled once the fluctuation in the wheel acceleration subsides, and the slip judgment process can be performed.

[0093] In the vehicle 1, when the wheel acceleration occurs even when the tires are not spinning, such as during rapid acceleration, it is not determined that the wheels 2 are slipping, so that the occurrence of torque down unintended by the driver can be suppressed.

[0094] Furthermore, the vehicle 1 uses both the slip determination process using the first wheel slip threshold Ts1 and the slip determination process using the second wheel slip threshold Ts2.

[0095] Therefore, the vehicle 1 can handle both cases where the wheels 2 slip instantly due to the input of high torque, and cases where the amount of slip of the wheels 2 increases gradually due to a relatively small torque.

[0096] Since the vehicle 1 performs slip determination processing for each wheel 2, it can detect changes in wheel acceleration more quickly and determine whether or not the wheel 2 is slipping at an earlier stage than when determining whether or not the wheel 2 is slipping using the average wheel acceleration of multiple wheels, such as the left and right wheels.

[0097] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0098] For example, the present invention is also applicable to vehicles whose drive wheels are driven by so-called in-wheel motors, and so-called parallel hybrid vehicles. [Explanation of symbols]

[0099] 1. Vehicle 2...wheels 2a...Front wheel 2b…Rear wheel 3…First drive unit 4…1st differential gear 5…Second drive unit 6…Second differential gear 7. Battery 8…Control unit 9...Accelerator opening sensor 10...Vehicle speed sensor 11...Accelerometer 12...Wheel speed sensor

Claims

1. A rough road determination process is carried out to determine whether the vehicle is traveling on a rough road; When it is determined that the vehicle is traveling on a rough road by the rough road determination process, the slip determination process for determining whether the vehicle is slipping is terminated or the execution of the slip determination process is prohibited. If it is determined that the vehicle is slipping as a result of the slip determination process, the output of the drive source of the vehicle is reduced, The slip determination process determines that the vehicle is slipping when the wheel acceleration exceeds a predetermined positive slip determination threshold for a predetermined slip determination time, The vehicle control method, wherein the rough road determination process determines that the vehicle is traveling on a rough road when the wheel acceleration falls below a predetermined negative rough road determination threshold value.

2. 2. The vehicle control method according to claim 1, wherein the rough road determination threshold is a value obtained by subtracting the slip determination threshold and an offset amount of the wheel acceleration from the wheel acceleration.

3. 2. The vehicle control method according to claim 1, wherein the rough road determination process is performed when the vehicle is accelerating.

4. 4. The method for controlling a vehicle according to claim 3, further comprising the step of determining that the vehicle is accelerating when the driving force of the vehicle is greater than the running resistance.

5. 2. The vehicle control method according to claim 1, characterized in that, when it is determined by the rough road determination process that the vehicle is traveling on a rough road, the determination that the vehicle is traveling on a rough road is maintained until the wheel acceleration exceeds a predetermined rough road determination release threshold continuously for more than a predetermined rough road determination release time that is set in advance.

6. The vehicle is driven by a motor, 2. The vehicle control method according to claim 1, wherein the slip determination threshold is set in accordance with a driving force of the motor.

7. the slip determination thresholds are a first wheel slip threshold set so as not to be exceeded by the wheel acceleration generated when the vehicle accelerates, and a second wheel slip threshold set so as to be greater than the first wheel slip threshold and not to be exceeded by fluctuations in the wheel acceleration during traveling, 7. The vehicle control method according to claim 6, wherein the length of the slip determination time is set longer in the slip determination process using the first wheel slip threshold than in the slip determination process using the second wheel slip threshold.

8. 2. The vehicle control method according to claim 1, wherein the slip determination process is performed for each wheel of the vehicle.

9. a rough road determination process execution unit that executes a rough road determination process for determining whether or not a vehicle is traveling on a rough road; a slip determination process execution unit that executes a slip determination process to determine whether or not a vehicle is slipping; an output control unit that reduces an output of a drive source of the vehicle when it is determined that the vehicle is slipping; the slip determination process execution unit terminates the slip determination process or prohibits execution of the slip determination process when it is determined by the rough road determination process that the vehicle is traveling on a rough road, and determines that the vehicle is slipping when the wheel acceleration exceeds a predetermined positive slip determination threshold value for a predetermined slip determination time, The vehicle control device, wherein the rough road determination process execution unit determines that the vehicle is traveling on a rough road when the wheel acceleration falls below a predetermined negative rough road determination threshold value.

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