Vehicle control device

Abstract

The invention provides a vehicle control device capable of improving calculation accuracy of an estimated value of a vehicle body speed when a vehicle is in a slipping state. A vehicle control device (1) is provided with: a basic vehicle body speed calculation unit (13) that calculates a basic vehicle body speed on the basis of the wheel speeds of a plurality of wheels of a vehicle detected by a wheel speed sensor (21); a vehicle body speed estimation unit (14) that calculates an estimated vehicle body speed on the basis of the base vehicle body speed and the front-rear acceleration detected by the front-rear acceleration sensor (22); and a slip determination unit (15) that determines whether or not the vehicle is in a slip state. The vehicle body speed estimation unit (14) calculates an estimated vehicle body speed by performing a predetermined limit process on the longitudinal acceleration, and switches the mode of the limit process when it is determined that the vehicle is in a slipping state during acceleration and deceleration of the vehicle.

Description

Technical Field

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

[0002] In recent years, efforts to provide access to sustainable transportation systems that take into account vulnerable road users have become increasingly active. To achieve this, research and development efforts are underway to further improve traffic safety and convenience through research and development related to driver assistance.

[0003] For example, Patent Documents 1 to 3 disclose a device that estimates vehicle speed based on detection results from wheel speed sensors and longitudinal acceleration sensors provided on a vehicle and uses the estimated vehicle speed for various controls including vehicle driving assistance.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 7105780

[0007] Patent Document 2: Japanese Patent No. 6679348

[0008] Patent Document 3: Japanese Patent No. 5020388 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] When a vehicle is skidding, the pitching of the vehicle causes a discrepancy between the detection results of the longitudinal acceleration sensors and the actual vehicle body acceleration. Consequently, the vehicle speed estimated based on the longitudinal acceleration sensors (estimated vehicle body speed) may be inaccurate. Proper vehicle control in a skidding state requires highly accurate estimated vehicle body speed, and therefore there is room for improvement in the calculation accuracy of the estimated vehicle body speed.

[0011] The present invention provides a vehicle control device capable of improving the calculation accuracy of an estimated value of vehicle body speed when the vehicle is in a slipping state.

[0012] Means for solving problems

[0013] The present invention is a vehicle control device comprising:

[0014] a wheel speed acquiring unit for acquiring wheel speeds of a plurality of wheels of the vehicle based on detection results of the wheel speed sensors;

[0015] an acceleration acquiring unit for acquiring the acceleration in the front-rear direction of the vehicle based on a detection result of the acceleration sensor;

[0016] a calculation unit that calculates a first vehicle body speed of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors;

[0017] an estimating unit that calculates a second vehicle body speed as an estimated value of the vehicle body speed based on the first vehicle body speed and the acceleration detected by the acceleration sensor; and

[0018] a skidding determination unit for determining whether the vehicle is in a skidding state,

[0019] The estimating unit calculates the second vehicle body speed by performing a predetermined restriction process on the acceleration detected by the acceleration sensor, and switches a mode of the restriction process when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to improve the calculation accuracy of the estimated value of the vehicle body speed when the vehicle is in a slipping state. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a block diagram showing a vehicle control device 1 according to one embodiment of the present invention.

[0023] Figure 2 It is a block diagram explaining the calculation of the basic vehicle body speed.

[0024] Figure 3 This is a block diagram illustrating calculation of the estimated vehicle body speed.

[0025] Figure 4 An example of a graph showing the time history of the wheel speed and the body speed when the vehicle is in a slipping state while accelerating (upper side) and a graph showing the time history of the wheel speed and the body speed when the vehicle is in a gripping state (lower side).

[0026] Figure 5 This is a block diagram showing an example of rate limiting processing when the vehicle is in a gripping state.

[0027] Figure 6 A graph showing the time history of the wheel speed and the vehicle body speed when the vehicle is accelerating and in a slipping state (upper side) and a graph showing the time history of the longitudinal acceleration (lower side) are shown.

[0028] Figure 7 This is a block diagram showing an example of rate limiting processing when the vehicle is in a slipping state.

[0029] Figure 8 This is a graph showing changes in rate values when the cutoff frequency of the low-pass filter is changed from 1.0 Hz to 0.1 Hz in the rate limiting process.

[0030] Figure 9 This shows the control flow of the switching rate limit process.

[0031] Figure 10 This is a block diagram showing an example of a rate limiting process when an abnormality is detected in the longitudinal acceleration sensor 22 and it is determined that the vehicle is not in a slipping state.

[0032] Description of Reference Numerals

[0033] 1 Vehicle control device

[0034] 11 Wheel speed acquisition unit

[0035] 12 Front and rear acceleration acquisition unit (acceleration acquisition unit)

[0036] 13 Basic vehicle speed calculation unit (calculation unit)

[0037] 14 Vehicle speed estimation unit (estimation unit)

[0038] 15. Slip Detection Unit

[0039] 16. Drive control unit

[0040] 21 Wheel speed sensor

[0041] 22 Front and rear acceleration sensors (accelerometers) DETAILED DESCRIPTION

[0042] Figure 1 This is a block diagram illustrating a vehicle control device 1 (hereinafter referred to simply as the control device 1 ) according to one embodiment of the present invention. The control device 1 is mounted on a vehicle, such as a four-wheeled vehicle. The vehicle uses an internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, or a combination thereof as a drive source. For example, the vehicle is a four-wheel drive vehicle that distributes the rotational force generated by the drive source to the front and rear wheels. The control device 1 controls the distribution of the driving force to each wheel of the four-wheel drive vehicle.

[0043] The control device 1 communicates with the vehicle sensor 2 mounted on the vehicle and receives signals representing various information from the vehicle sensor 2. The control device 1 is configured as a computer having a control operation device, a storage device, and an input / output device as a physical structure. The control operation device is, for example, an ECU (Electronic Control Unit) composed of a controller such as a CPU (Central Processing Unit), which performs operation processing and controls the storage device and the input / output device. The storage device includes, for example, a main storage device and an auxiliary storage device. The main storage device is, for example, composed of a RAM (Random Access Memory). In addition, the auxiliary storage device is, for example, composed of a ROM (Read Only Memory). The input / output device includes, for example, an input device that inputs data from the outside and sends it to the storage device, and an output device that outputs the operation results calculated by the control operation device and stored in the storage device to the outside.

[0044] The control device 1 reads a program stored in the ROM into the RAM, for example, and executes the program read into the RAM by the CPU, thereby executing the processing of the control flow described below.

[0045] The vehicle sensors 2 detect various data, for example, when the vehicle is parked and moving. For example, the vehicle sensors 2 include a wheel speed sensor 21 that detects the wheel speeds of multiple wheels (the right front wheel FR, the left front wheel FL, the right rear wheel RR, and the left rear wheel RL); and a longitudinal acceleration sensor 22 that detects acceleration in the longitudinal direction, which is the vehicle's direction of travel (hereinafter also referred to as longitudinal acceleration). The multiple wheel speed sensors 21 are installed in the rotating portion of the vehicle's drive system and detect the wheel speed (specifically, the rotational speed) of each wheel. The wheel speed sensors 21 transmit signals containing information about the detected wheel speeds to the control device 1. The longitudinal acceleration sensors 22 similarly detect acceleration in the longitudinal direction and transmit signals containing information about the detected acceleration to the control device 1.

[0046] Next, the functional configuration of the control device 1 will be described. The control device 1 includes a wheel speed acquisition unit 11 , a longitudinal acceleration acquisition unit 12 , a base vehicle speed calculation unit 13 , a vehicle speed estimation unit 14 , a slip determination unit 15 , and a drive control unit 16 .

[0047] The wheel speed acquisition unit 11 receives signals from the wheel speed sensor 21 and acquires the wheel speeds of the plurality of wheels. The longitudinal acceleration acquisition unit 12 receives signals from the longitudinal acceleration sensor 22 and acquires the longitudinal acceleration of the vehicle.

[0048] The basic vehicle body speed calculation unit 13 calculates a basic vehicle body speed that is a vehicle speed based on the wheel speeds detected by the wheel speed sensors 21 . Figure 2 This is a block diagram illustrating the calculation of the basic vehicle speed. The wheel speeds of each wheel detected by the wheel speed sensor 21 and the longitudinal acceleration detected by the longitudinal acceleration sensor 22 are input to the basic vehicle speed calculation unit 13. In this embodiment, when the vehicle is accelerating, the basic vehicle speed calculation unit 13 uses the minimum wheel speed among the multiple wheel speeds as the basic vehicle speed. On the other hand, when the vehicle is decelerating, the basic vehicle speed calculation unit 13 uses the maximum wheel speed among the multiple wheel speeds as the basic vehicle speed.

[0049] The vehicle body speed estimating unit 14 calculates an estimated vehicle body speed, which is an estimated value of the vehicle body speed, based on the basic vehicle body speed and the longitudinal acceleration. Figure 3 This is a block diagram illustrating the calculation of the estimated vehicle speed. The longitudinal acceleration detected by the longitudinal acceleration sensor 22 is input to the vehicle speed estimating unit 14. The vehicle speed estimating unit 14 performs a rate limiting process (described later) on the input longitudinal acceleration to calculate a rate value for the estimated vehicle speed. The vehicle speed estimating unit 14 then integrates the rate value to calculate the estimated vehicle speed. At this time, the base vehicle speed at a predetermined time (e.g., the base vehicle speed at the start of acceleration) is used as the initial value for the integration operation.

[0050] The slip determination unit 15 determines whether the vehicle is in a slip state. Specifically, the slip determination unit 15 determines the slip state of the vehicle based on the basic vehicle body speed and the estimated vehicle body speed.

[0051] Here, the slipping state is a state in which all wheels of the vehicle are spinning and not gripping the road. On the other hand, the non-slipping state (also referred to as gripping state) is a state in which at least one wheel is gripping the road. Figure 4 These graphs show the time history of the wheel speed and body speed of a vehicle while accelerating on a low-friction road (e.g., frozen, snowy, or unpaved roads). The upper graph shows the vehicle in a slipping state, while the lower graph shows the vehicle in a gripping state with the right rear wheel RR. In each graph, the wheel speed of the left front wheel FL is represented by a thin solid line, the wheel speed of the right front wheel FR by a thin dashed line, the wheel speed of the left rear wheel RL by a dashed-dotted line, and the wheel speed of the right rear wheel RR by a dashed-dotted line. The estimated body speed calculated by the body speed estimating unit 14 is represented by a thick solid line, and the actual body speed is represented by a thick dashed line. The wheel speeds of each wheel are sensor values detected by the wheel speed sensor 21.

[0052] exist Figure 4In the graph above , the wheel speeds of all wheels are greater than the actual vehicle speed. The basic vehicle speed calculation unit 13 calculates the wheel speed of the right rear wheel RR, which is the minimum wheel speed, as the basic vehicle speed. The vehicle speed estimation unit 14 calculates the estimated vehicle speed by integrating the longitudinal acceleration detected by the longitudinal acceleration acquisition unit 12 after rate limiting. The slip determination unit 15 compares the basic vehicle speed with the estimated vehicle speed and, if it determines that the basic vehicle speed is greater than the estimated vehicle speed, determines that the vehicle is slipping.

[0053] exist Figure 4 In the lower graph, the right front wheel FR, left front wheel FL, and left rear wheel RL are spinning, and their wheel speeds are greater than the actual vehicle speed. However, the right rear wheel RR is gripping the road, and its wheel speed is approximately the same as the actual vehicle speed. The base vehicle speed calculation unit 13 calculates the wheel speed of the right rear wheel RR, which is the minimum wheel speed, as the base vehicle speed. The vehicle speed estimation unit 14 calculates the estimated vehicle speed by integrating the longitudinal acceleration detected by the longitudinal acceleration sensor 22 after rate limiting. The slip determination unit 15 compares the base vehicle speed with the estimated vehicle speed. If the base vehicle speed and the estimated vehicle speed are approximately the same, the vehicle is determined not to be slipping.

[0054] The skid determination unit 15 is not limited to the above-described method for determining a skid state. For example, the skid determination unit 15 may be configured to determine whether the vehicle is in a skid state based on information from an external temperature sensor installed in the vehicle, information from a camera that detects frozen or snowy roads, or unpaved roads, detection information obtained through communication with the outside of the vehicle, or deformation information of the vehicle chassis.

[0055] return Figure 1 The drive control unit 16 controls the driving state of the vehicle based on the estimated vehicle body speed estimated by the vehicle body speed estimating unit 14. Specifically, if the vehicle is an all-wheel drive vehicle, the drive force distribution to the plurality of wheels is controlled based on the estimated vehicle body speed.

[0056] Next, the rate limiting process executed by the vehicle body speed estimating section 14 will be described in detail.

[0057] Figure 5 This is a block diagram illustrating the rate limiting process performed by the vehicle body speed estimation unit 14 when the vehicle is in a gripping state. Figure 5 The vehicle body speed is estimated by the speed limiting process until the vehicle is determined to be in a slipping state. When the control device 1 determines that the vehicle is in a slipping state, it switches to the following Figure 7 Rate limiting processing.

[0058] like Figure 5 As shown, control device 1 applies a low-pass filter (also referred to as an LPF in the figure) to the longitudinal acceleration, which is the sensor value detected by longitudinal acceleration sensor 22. This filtering process gradually reduces (eliminates) frequency components above a predetermined threshold value contained in the sensor value. For example, control device 1 sets the predetermined threshold, or cutoff frequency, to 1.0 Hz, gradually reducing frequency components above 1.0 Hz contained in the sensor value. This reduces noise contained in the sensor value.

[0059] Furthermore, the control device 1 adds a predetermined margin to the longitudinal acceleration after the low-pass filtering. The addition of this margin takes into account the sensor value deviation of the longitudinal acceleration sensor 22.

[0060] Furthermore, as a measure to prevent the longitudinal acceleration from canceling out on a gradient road, such as an uphill or downhill slope, the control device 1 sets a minimum velocity value. Furthermore, the control device 1 outputs the maximum of the minimum velocity value and the value obtained by low-pass filtering the longitudinal acceleration sensor value and adding a margin as the velocity value.

[0061] In this manner, by performing the rate limiting process on the longitudinal acceleration as the sensor value to calculate the rate value, it is possible to suppress a sudden change component from being included in the estimated vehicle body speed obtained by integrating the rate value.

[0062] Figure 6 A graph showing the time history of the wheel speed and the vehicle body speed when the vehicle is in a slipping state, for example, when accelerating on a road with a low friction coefficient (upper side), and a graph showing the time history of the longitudinal acceleration (lower side). Figure 4 The graph on the upper side is the same as the graph on the lower side. In the graph on the lower side, the sensor values detected by the front and rear acceleration sensors 22 are represented by thin dotted lines, the sensor values after low-pass filtering are represented by thin solid lines, the above-mentioned margin is represented by the oblique line area, the minimum value of the above-mentioned rate value is represented by a single dotted line, the final calculated rate value is represented by a thick solid line, and the actual front and rear acceleration of the vehicle is represented by a thick dotted line. In addition, Figure 6 In the figure, it is shown that Figure 5 In the case of calculating the estimated vehicle body speed by the rate limiting process, the cutoff frequency of the low-pass filter is set to 1.0 Hz.

[0063] like Figure 6As shown, at time t1, the longitudinal acceleration sensor value increases significantly. This is because at time t1, the vehicle is in a slipping state, resulting in an increase in the longitudinal acceleration sensor value due to pitching (i.e., tilting) in the vehicle's longitudinal direction. Although the longitudinal acceleration sensor value increases significantly, the actual longitudinal vehicle acceleration does not increase significantly due to the vehicle's slipping and wheel spin. This increase in the longitudinal acceleration sensor value caused by pitching is one of the factors that causes the velocity value to deviate from the actual vehicle acceleration. In this case, the estimated vehicle velocity calculated by integrating the velocity value is greater than the actual vehicle velocity.

[0064] Therefore, when it is determined that the vehicle is in a slipping state during acceleration, the control device 1 switches the rate limiting process. Specifically, when it is determined that the vehicle is in a slipping state during acceleration, the control device 1 switches the rate limiting process to a method that suppresses the influence of the longitudinal acceleration caused by the vehicle's pitching.

[0065] Specifically, if Figure 7 As shown in FIG, when it is determined that the vehicle is in a slipping state during acceleration, the control device 1 changes the cutoff frequency of the low-pass filter from 1.0 Hz to 0.1 Hz and performs filtering processing to gradually reduce (remove) the frequency components above 0.1 Hz contained in the detected longitudinal acceleration. By lowering the cutoff frequency, as shown in FIG. Figure 8 As shown, control device 1 can calculate a rate value that gradually reduces the increase in sensor value caused by pitching. Therefore, compared to a case where the cutoff frequency is set to 1.0 Hz, the rate value can be closer to the actual vehicle acceleration, improving the accuracy of calculating the estimated vehicle speed during a vehicle skidding state. As a result, control device 1 can appropriately control the vehicle's driving state.

[0066] In addition, if Figure 6 As shown in , when the vehicle is in a slipping state, the margin added to the sensor values of the front and rear accelerations also becomes one of the causes of the deviation between the velocity value and the actual vehicle body acceleration. Figure 7 As shown in FIG. 1 , when it is determined that the vehicle is in a slipping state during acceleration, the control device 1 performs an offset process to cancel the addition of the margin. Figure 8 As shown, the rate value calculated by the rate limiting process can be made closer to the actual vehicle body acceleration, and the calculation accuracy of the estimated vehicle body speed when the vehicle is in a slipping state can be improved.

[0067] In addition to canceling the margin, this offset processing may also include canceling the longitudinal acceleration detected when the vehicle is stopped from the acceleration detected when the vehicle is accelerating. Specifically, the control device 1 may also include a process for learning the sensor value deviation based on the detection results of the longitudinal acceleration sensor 22 each time the vehicle is stopped, and canceling this sensor value deviation based on the acceleration detected when the vehicle is accelerating. This allows the acceleration detected by the acceleration sensor to be closer to the actual vehicle body acceleration.

[0068] Figure 9 The following figure shows an example of a control flow executed by control device 1. Control device 1 receives detection results from wheel speed sensor 21 and longitudinal acceleration sensor 22, and acquires wheel speed and longitudinal acceleration (step S1). Control device 1 calculates a base vehicle body speed based on the acquired wheel speed (step S2).

[0069] Next, the control device 1 applies rate limiting processing to the acquired longitudinal acceleration (step S3). If a slip state is not determined, the control device 1 applies rate limiting processing with the cutoff frequency of the low-pass filter used in the rate limiting process set to 1.0 Hz, a normal value. The control device 1 then calculates an estimated vehicle body speed based on the rate value obtained through the rate limiting process (step S4).

[0070] Next, the control device 1 determines whether the base vehicle speed is greater than the estimated vehicle speed (step S5). If the base vehicle speed is not greater than the estimated vehicle speed but is substantially the same (step S5: No), the control device 1 determines that the vehicle is not slipping, that is, is gripping the road (step S6) and sets the cutoff frequency of the low-pass filter to 1.0 Hz (step S7). On the other hand, if the base vehicle speed is greater than the estimated vehicle speed (step S5: Yes), the control device 1 determines that the vehicle is slipping (step S8) and sets the cutoff frequency of the low-pass filter to 0.1 Hz (step S9).

[0071] In the above description, the control device 1 calculates the estimated vehicle body speed based on the detection results of the front and rear acceleration sensors 22. However, in the event that an abnormality (failure) of the front and rear acceleration sensors 22 is detected, a structure can be considered in which the speed value is calculated based on the total driving force of the vehicle without using the detection results of the front and rear acceleration sensors 22.

[0072] Figure 10This is a block diagram showing an example of rate limiting processing when an abnormality is detected in the front and rear acceleration sensors 22 and the vehicle is determined to be not in a slipping state. In this case, the control device 1 uses the total driving force of the vehicle as the input value for the rate limiting processing. More specifically, the control device 1 calculates the front and rear acceleration (also called converted front and rear acceleration) converted from the total driving force and the vehicle weight by dividing the value obtained by subtracting the vehicle's rolling resistance and air resistance from the total driving force by the vehicle weight. In addition, when the vehicle is stopped, the control device 1 sets the converted front and rear acceleration to zero. In addition, the vehicle weight can be the weight of the vehicle itself or a weight that takes into account the weight of the occupants.

[0073] The control device 1 does not filter the converted longitudinal acceleration using a low-pass filter, but instead adds a margin to the converted longitudinal acceleration. The control device 1 then outputs the maximum of the value obtained by adding the margin to the converted longitudinal acceleration and the minimum value of the velocity value as a velocity value, and calculates the estimated vehicle body velocity based on this velocity value.

[0074] On the other hand, when an abnormality is detected in the front and rear acceleration sensors 22, if it is determined that the vehicle is in a slipping state, the control device 1 uses a pre-prepared fixed value as the speed value. This fixed value is, for example, an acceleration equivalent to an icy road surface (e.g., 0.007 to 0.01 m / s). 2 The control device 1 calculates the estimated vehicle body speed based on the rate value as the fixed value.

[0075] In this manner, even when an abnormality of the longitudinal acceleration sensor 22 is detected and an appropriate longitudinal acceleration sensor value cannot be obtained, the control device 1 can calculate the velocity value and, as a result, the estimated vehicle body speed.

[0076] In addition, the control device 1 can determine that the front and rear acceleration sensors 22 are abnormal when a fault signal is obtained from the front and rear acceleration sensors 22, or can determine that the front and rear acceleration sensors 22 are abnormal when the detection value of the front and rear acceleration sensors 22 exceeds the abnormality determination threshold.

[0077] While one embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to this embodiment. It is apparent that those skilled in the art will be able to devise various variations or modifications within the scope of the claims, and it should be understood that these variations and modifications also fall within the technical scope of the present invention. Furthermore, the various constituent elements in the above-described embodiments may be arbitrarily combined without departing from the spirit of the invention.

[0078] For example, in the above embodiment, the control of the control device 1 during acceleration of the vehicle has been described as an example, but the present invention is not limited thereto, and similar control can be performed during deceleration of the vehicle.

[0079] This specification includes at least the following matters: In parentheses, corresponding components in the above-described embodiment are shown as an example, but the present invention is not limited thereto.

[0080] (1) A vehicle control device (vehicle control device 1) comprising:

[0081] a wheel speed acquisition unit (wheel speed acquisition unit 11 ) that acquires the wheel speeds of a plurality of wheels of the vehicle based on detection results of a wheel speed sensor (wheel speed sensor 21 );

[0082] an acceleration acquisition unit (front-rear acceleration acquisition unit 12 ) that acquires the acceleration of the vehicle in the front-rear direction based on a detection result of an acceleration sensor (front-rear acceleration sensor 22 );

[0083] a calculation unit (basic vehicle body speed calculation unit 13 ) that calculates a first vehicle body speed (basic vehicle body speed) of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors;

[0084] an estimating unit (vehicle body speed estimating unit 14 ) that calculates a second vehicle body speed (estimated vehicle body speed) as an estimated value of the vehicle body speed based on the first vehicle body speed and the acceleration detected by the acceleration sensor; and

[0085] a slip determination unit (slip determination unit 15 ) for determining whether the vehicle is in a slip state;

[0086] The estimating unit calculates the second vehicle body speed by performing a predetermined restriction process on the acceleration detected by the acceleration sensor, and switches a mode of the restriction process when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle.

[0087] According to (1), when the vehicle is in a slipping state during acceleration or deceleration, the method of limiting the detected acceleration is switched, thereby improving the calculation accuracy of the second vehicle body speed (estimated value of the vehicle body speed) when the vehicle is in a slipping state.

[0088] (2) The vehicle control device according to (1), wherein:

[0089] The limiting process includes a filtering process in which frequency components exceeding a predetermined threshold value in the acceleration detected by the acceleration sensor are gradually reduced.

[0090] When it is determined that the vehicle is not in the slipping state when the vehicle accelerates or decelerates, the estimating unit sets the prescribed threshold to a first threshold (1.0 Hz), and when it is determined that the vehicle is in the slipping state when the vehicle accelerates or decelerates, the estimating unit sets the prescribed threshold to a second threshold (0.1 Hz) lower than the first threshold.

[0091] According to (2), when it is determined that the vehicle is in a slipping state during acceleration or deceleration, the predetermined threshold value for the filtering process is set to a second threshold value lower than the first threshold value, thereby suppressing the influence of acceleration caused by the pitch of the vehicle.

[0092] (3) The vehicle control device according to (1) or (2), wherein:

[0093] The slip determination unit determines that the vehicle is not in the slip state when at least one wheel is gripping the ground, and determines that the vehicle is in the slip state when all wheels are not gripping the ground.

[0094] According to (3), the slip state can be appropriately determined according to the state of the wheel.

[0095] (4) The vehicle control device according to any one of (1) to (3), wherein:

[0096] When the vehicle is accelerating, the calculation unit calculates a minimum wheel speed among the wheel speeds of the plurality of wheels as the first vehicle body speed.

[0097] According to (4), when the vehicle is accelerating, the first vehicle body speed can be brought close to the actual vehicle body speed.

[0098] (5) The vehicle control device according to (4), wherein:

[0099] The slip determination unit determines that the vehicle is in the slip state when the second vehicle body speed is greater than the first vehicle body speed, and determines that the vehicle is not in the slip state when the second vehicle body speed is substantially the same as the first vehicle body speed.

[0100] According to (5), the slip state can be appropriately determined based on the first vehicle body speed based on the detected wheel speed and the second vehicle body speed based on the detected acceleration.

[0101] (6) The vehicle control device according to any one of (1) to (5), wherein:

[0102] The limiting process includes a process of canceling the acceleration detected when the vehicle is stopped from the acceleration detected when the vehicle is accelerating or decelerating.

[0103] According to (6), the acceleration detected by the acceleration sensor can be made closer to the actual acceleration of the vehicle, and thus the calculation accuracy of the second vehicle body speed when the vehicle is in a slipping state can be further improved.

[0104] (7) The vehicle control device according to any one of (1) to (6), wherein:

[0105] The vehicle control device further includes a drive control unit (drive control unit 16 ) that controls the driving state of the vehicle.

[0106] The drive control unit controls the drive state according to the second vehicle body speed.

[0107] According to (7), even when the vehicle is in a slipping state, the accuracy of the second vehicle body speed is high, so the driving state of the vehicle can be appropriately controlled in the slipping state.

[0108] (8) The vehicle control device according to (7), wherein:

[0109] The vehicle is an all-wheel drive vehicle,

[0110] The drive control unit controls distribution of driving force to a plurality of wheels of the vehicle according to the second vehicle body speed.

[0111] According to (8), even when the vehicle is in a slipping state, the accuracy of the second vehicle body speed is high, so that the driving force distribution to the plurality of wheels can be appropriately controlled in the slipping state.

[0112] (9) The vehicle control device according to any one of (1) to (8), wherein:

[0113] When it is determined that the vehicle is in the slipping state when the vehicle is accelerating or decelerating, the estimating unit switches the limiting process to a method for suppressing the influence of the acceleration caused by pitching of the vehicle.

[0114] According to (9), when the vehicle is in a slipping state during acceleration and deceleration, the limiting process for the detected acceleration is switched to a method for suppressing the influence of the acceleration caused by the bumping of the vehicle, thereby improving the calculation accuracy of the second vehicle body speed (estimated value of the vehicle body speed) when the vehicle is in a slipping state.

[0115] (10) The vehicle control device according to any one of (1) to (9), wherein:

[0116] The estimating unit detects an abnormality in the acceleration sensor and, when determining that the vehicle is in the slipping state while the vehicle is accelerating or decelerating, calculates the second vehicle body speed based on an acceleration that is a fixed value prepared in advance.

[0117] According to (10), even when the acceleration sensor is abnormal, the second vehicle body speed can be appropriately calculated.

Claims

1. A vehicle control device comprising: a wheel speed acquiring unit for acquiring wheel speeds of a plurality of wheels of the vehicle based on detection results of the wheel speed sensors; an acceleration acquiring unit for acquiring the acceleration in the front-rear direction of the vehicle based on a detection result of the acceleration sensor; a calculation unit that calculates a first vehicle body speed of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors; an estimating unit that calculates a second vehicle body speed as an estimated value of the vehicle body speed based on the first vehicle body speed and the acceleration detected by the acceleration sensor; as well as a skidding determination unit for determining whether the vehicle is in a skidding state, in, The estimating unit calculates the second vehicle body speed by performing a predetermined limiting process on the acceleration detected by the acceleration sensor, and switches a method of the limiting process when it is determined that the vehicle is in the slipping state during acceleration or deceleration of the vehicle.

2. The vehicle control device according to claim 1, wherein: The limiting process includes a filtering process in which frequency components exceeding a predetermined threshold value in the acceleration detected by the acceleration sensor are gradually reduced. When it is determined that the vehicle is not in the slipping state when the vehicle accelerates or decelerates, the estimation unit sets the prescribed threshold to a first threshold, and when it is determined that the vehicle is in the slipping state when the vehicle accelerates or decelerates, the estimation unit sets the prescribed threshold to a second threshold that is lower than the first threshold.

3. The vehicle control device according to claim 1, wherein: The slip determination unit determines that the vehicle is not in the slip state when at least one wheel is gripping the ground, and determines that the vehicle is in the slip state when all wheels are not gripping the ground.

4. The vehicle control device according to claim 1, wherein: When the vehicle is accelerating, the calculation unit calculates a minimum wheel speed among the wheel speeds of the plurality of wheels as the first vehicle body speed.

5. The vehicle control device according to claim 4, wherein: The slip determination unit determines that the vehicle is in the slip state when the second vehicle body speed is greater than the first vehicle body speed, and determines that the vehicle is not in the slip state when the second vehicle body speed is substantially the same as the first vehicle body speed.

6. The vehicle control device according to claim 1, wherein: The limiting process includes a process of canceling the acceleration detected when the vehicle is stopped from the acceleration detected when the vehicle is accelerating or decelerating.

7. The vehicle control device according to claim 1, wherein: The vehicle control device further includes a drive control unit that controls a drive state of the vehicle. The drive control unit controls the drive state according to the second vehicle body speed.

8. The vehicle control device according to claim 7, wherein: The vehicle is an all-wheel drive vehicle, The drive control unit controls distribution of driving force to a plurality of wheels of the vehicle according to the second vehicle body speed.

9. The vehicle control device according to any one of claims 1 to 8, wherein: When it is determined that the vehicle is in the slipping state when the vehicle is accelerating or decelerating, the estimating unit switches the limiting process to a method for suppressing the influence of the acceleration caused by pitching of the vehicle.

10. The vehicle control device according to any one of claims 1 to 8, wherein: The estimating unit detects an abnormality in the acceleration sensor and, when determining that the vehicle is in the slipping state while the vehicle is accelerating or decelerating, calculates the second vehicle body speed based on an acceleration that is a fixed value prepared in advance.

Images