Vehicle control device

Abstract

To provide a vehicle control device capable of improving the calculation accuracy of an estimation value of a vehicle body speed during a slip state of a vehicle.SOLUTION: A vehicle control device 1 comprises: a base vehicle body speed calculation unit 13 that calculates a base vehicle body speed on the basis of wheel speeds of a plurality of wheels of the 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 longitudinal acceleration detected by a longitudinal 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 the estimated vehicle body speed by performing predetermined limit processing on the longitudinal acceleration, and when it is determined that the vehicle is in a slip state during acceleration or deceleration of the vehicle, switches the mode of the limit processing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, efforts to provide access to sustainable transport systems that take into consideration vulnerable transport participants have become more active. To achieve this, we are focusing on research and development into driver assistance to further improve road safety and convenience.

[0003] For example, Patent Documents 1 to 3 disclose devices that estimate vehicle speed based on the detection results of wheel speed sensors and longitudinal acceleration sensors installed on a vehicle, and use the estimated vehicle speed for various controls including vehicle driving assistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7105780 [Patent Document 2] Patent No. 6679348 [Patent Document 3] Patent No. 5020388 Summary of the Invention [Problem to be solved by the invention]

[0005] When the vehicle slips, a discrepancy occurs between the detection result of the longitudinal acceleration sensor and the actual acceleration of the vehicle body due to pitching of the vehicle, and the vehicle speed estimated based on the longitudinal acceleration sensor (estimated vehicle body speed) may not be high. Appropriate vehicle control in a slip state requires a highly accurate estimated vehicle body speed, so there is room for improvement in the accuracy of calculating the estimated vehicle body speed.

[0006] The present invention provides a vehicle control device that can improve the accuracy of calculating an estimated value of the vehicle speed when the vehicle is in a slipping state. [Means for solving the problem]

[0007] The present invention provides a wheel speed acquisition unit that acquires wheel speeds of a plurality of wheels of a vehicle from detection results of wheel speed sensors; an acceleration acquisition unit that acquires acceleration in the front-rear direction of the vehicle from a detection result of an acceleration sensor; a calculation unit that calculates a first vehicle speed of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors; an estimation unit that calculates a second vehicle speed that is an estimated value of the vehicle speed of the vehicle based on the first vehicle speed and the acceleration detected by the acceleration sensor; a slip determination unit that determines whether the vehicle is in a slip state, The estimation unit calculating the second vehicle speed by performing a predetermined limit process on the acceleration detected by the acceleration sensor; When it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the mode of the limit processing is switched. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the accuracy of calculating an estimated value of the vehicle speed when the vehicle is in a slipping state. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a vehicle control device 1 according to an embodiment of the present invention. [Figure 2] FIG. 4 is a block diagram illustrating calculation of a base vehicle speed. [Figure 3] FIG. 4 is a block diagram illustrating calculation of an estimated vehicle speed. [Figure 4]An example of a graph (top) showing the time history of wheel speed and vehicle speed when the vehicle is accelerating and slipping, and an example of a graph (bottom) showing the time history of wheel speed and vehicle speed when the vehicle is in a grip state are shown. [Figure 5] FIG. 10 is a block diagram showing an example of a rate limit process when the vehicle is in a grip state. [Figure 6] 1 shows a graph (top) of the time history of wheel speed and vehicle body speed when the vehicle is accelerating and slipping, and a graph (bottom) of the time history of longitudinal acceleration. [Figure 7] FIG. 10 is a block diagram showing an example of a rate limit process when the vehicle is in a slip state. [Figure 8] 10 is a graph showing changes in rate values ​​when the cutoff frequency of a low-pass filter is changed from 1.0 Hz to 0.1 Hz in rate limit processing. [Figure 9] 10 shows a control flow for switching rate limit processing. [Figure 10] FIG. 10 is a block diagram showing an example of rate limit processing when an abnormality is detected in the longitudinal acceleration sensor 22 and it is determined that the vehicle is not in a slip state. DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a block diagram showing a vehicle control device 1 (hereinafter also simply referred to 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 of these as a drive source. The vehicle is, for example, a four-wheel drive vehicle in which rotational force generated by the drive source is distributed to front and rear wheels. The control device 1 controls the distribution of drive force to each wheel of the four-wheel drive vehicle.

[0011] The control device 1 communicates with vehicle sensors 2 mounted on the vehicle and receives signals indicating various types of information from the vehicle sensors 2. The control device 1 is physically configured as a computer equipped with a control and arithmetic device, a storage device, and an input / output device. The control and arithmetic device is, for example, an ECU (Electronic Control Unit) configured with a controller such as a CPU (Central Processing Unit), and executes arithmetic 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, configured with a RAM (Random Access Memory). The auxiliary storage device is, for example, configured with a ROM (Read Only Memory). The input / output device includes, for example, an input device that receives data from the outside and transmits it to the storage device, and an output device that outputs, to the outside, the results of calculations performed by the control and arithmetic device and stored in the storage device.

[0012] The control device 1 executes the control flow process described below by, for example, loading a program stored in a ROM into a RAM and executing the program loaded into the RAM by a CPU. Note that the control device 1 may have a physical configuration different from the above-described configuration.

[0013] The vehicle sensor 2 detects various data, for example, when the vehicle is stopped and running. The vehicle sensor 2 includes, for example, a wheel speed sensor 21 that detects the wheel speeds of multiple wheels (front right wheel FR, front left wheel FL, rear right wheel RR, and rear left wheel RL), and a longitudinal acceleration sensor 22 that detects acceleration in the longitudinal direction, which is the direction of travel of the vehicle (hereinafter also referred to as longitudinal acceleration). A plurality of wheel speed sensors 21 are provided on rotating parts in the drivetrain of the vehicle, and detect the wheel speed (specifically, rotational speed) of each wheel. The wheel speed sensor 21 transmits a signal including information about the detected wheel speed to the control device 1. The longitudinal acceleration sensor 22 similarly detects acceleration in the longitudinal direction, and transmits a signal including information about the detected acceleration to the control device 1.

[0014] Next, we will explain the functional configuration of the control device 1. The control device 1 includes a wheel speed acquisition unit 11, a longitudinal acceleration acquisition unit 12, a base vehicle body speed calculation unit 13, a vehicle body speed estimation unit 14, a slip determination unit 15, and a drive control unit 16.

[0015] The wheel speed acquisition unit 11 receives signals from the wheel speed sensor 21 and acquires the wheel speeds of a 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.

[0016] The base vehicle body speed calculation unit 13 calculates a base vehicle body speed, which is the speed of the vehicle based on the wheel speeds detected by the wheel speed sensors 21. FIG. 2 is a block diagram illustrating the calculation of the base vehicle body speed. The base vehicle body speed calculation unit 13 receives as input the wheel speeds of each wheel detected by the wheel speed sensors 21 and the longitudinal acceleration detected by the longitudinal acceleration sensor 22. In this embodiment, when the vehicle accelerates, the base vehicle body speed calculation unit 13 sets the minimum wheel speed among the wheel speeds of the multiple wheels as the base vehicle body speed. On the other hand, when the vehicle decelerates, the base vehicle body speed calculation unit 13 sets the maximum wheel speed among the wheel speeds of the multiple wheels as the base vehicle body speed.

[0017] The vehicle speed estimation unit 14 calculates an estimated vehicle speed, which is an estimated value of the vehicle speed, based on the base vehicle speed and the longitudinal acceleration. FIG. 3 is a block diagram for explaining the calculation of the estimated vehicle speed. The vehicle speed estimation unit 14 receives the longitudinal acceleration detected by the longitudinal acceleration sensor 22. The vehicle speed estimation unit 14 performs a rate limit process, which will be described later, on the received longitudinal acceleration to calculate a rate value of the estimated vehicle speed. The vehicle speed estimation unit 14 then integrates the rate value to calculate the estimated vehicle speed. At this time, the base vehicle speed at a predetermined time (for example, the base vehicle speed at the start of acceleration) is set as the initial value for the integration calculation.

[0018] The slip determination unit 15 determines whether the vehicle is in a slip state. Specifically, the slip determination unit 15 determines whether the vehicle is in a slip state based on the base vehicle speed and the estimated vehicle speed.

[0019] Here, a slip state is a state in which all of the vehicle's wheels are spinning and not gripping the road surface. On the other hand, a non-slip state (also referred to as a grip state) is a state in which at least one wheel is gripping the road surface. FIG. 4 is a graph showing the time history of wheel speed and vehicle speed when the vehicle is accelerating, for example, on a road surface with a low friction coefficient (e.g., a frozen or snow-covered road, or an unpaved road). The upper graph shows a case in which the vehicle is in a slip state, and the lower graph shows a case in which the right rear wheel RR is gripping the road surface. In each graph, the wheel speed of the left front wheel FL is shown 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-dot line, the wheel speed of the right rear wheel RR by a dashed-dot line, the wheel speed of the right rear wheel RR by a thick solid line, the estimated vehicle speed calculated by the vehicle speed estimation unit 14 by a thick dashed line, and the actual vehicle speed by a thick dashed line. The wheel speed of each wheel is a sensor value detected by the wheel speed sensor 21.

[0020] In the upper graph of Fig. 4, the wheel speeds of all wheels are higher than the actual vehicle speed. A base vehicle speed calculation unit 13 calculates the wheel speed of the right rear wheel RR, which is the smallest wheel speed, as the base vehicle speed, and a vehicle speed estimation unit 14 calculates an estimated vehicle speed by integrating the longitudinal acceleration detected by the longitudinal acceleration acquisition unit 12 after rate limit processing. A slip determination unit 15 compares the base vehicle speed with the estimated vehicle speed, and if it determines that the base vehicle speed is higher than the estimated vehicle speed, it determines that the vehicle is in a slip state.

[0021] In the lower graph of Figure 4, the wheel speeds of the right front wheel FR, left front wheel FL, and left rear wheel RL are spinning and are higher than the actual vehicle speed, but the right rear wheel RR is gripping the road surface, so the wheel speed of the right rear wheel RR is substantially 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 smallest wheel speed, as the base vehicle speed, and 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, and if it determines that the base vehicle speed is substantially the same as the estimated vehicle speed, it determines that the vehicle is not in a slip state.

[0022] The determination of the slip state by the slip determination unit 15 is not limited to the above. For example, the slip determination unit 15 may be configured to determine whether the vehicle is in a slip state based on information from an outside air temperature sensor provided in the vehicle, information from a camera that detects frozen or snow-covered roads or unpaved roads, probe information acquired through communication with the outside of the vehicle, distortion information of the vehicle chassis, etc.

[0023] 1, the drive control unit 16 controls the drive state of the vehicle based on the estimated vehicle speed estimated by the vehicle speed estimation unit 14. Specifically, if the vehicle is an all-wheel drive vehicle, the drive control unit 16 controls the distribution of drive force to the multiple wheels based on the estimated vehicle speed.

[0024] Next, the rate limiting process executed by the vehicle speed estimating unit 14 will be described in detail.

[0025] Figure 5 is a block diagram illustrating the rate limiting process by the vehicle speed estimator 14 when the vehicle is in a grip state. When the control device 1 is not in a slip state, it calculates the estimated vehicle speed based on the rate limiting process of Figure 5 until it is determined that the vehicle is in a slip state. Then, when it is determined that the vehicle is in a slip state, the control device 1 switches to the rate limiting process of Figure 7, which will be described later.

[0026] 5, the control device 1 performs a filtering process by applying a low-pass filter (also referred to as LPF in the figure) to the longitudinal acceleration, which is the sensor value detected by the longitudinal acceleration sensor 22, to attenuate (remove) frequency components contained in the sensor value that are equal to or greater than a predetermined threshold. For example, the control device 1 can reduce noise contained in the sensor value by setting the predetermined threshold, i.e., the cutoff frequency, to, for example, 1.0 Hz and attenuating frequency components contained in the sensor value that are equal to or greater than 1.0 Hz.

[0027] Furthermore, the control device 1 adds a predetermined margin to the longitudinal acceleration after the low-pass filter. The margin is added in consideration of the deviation of the sensor value of the longitudinal acceleration sensor 22.

[0028] Furthermore, the control device 1 sets a minimum value for the rate value as a measure to be taken when the longitudinal acceleration is canceled out on a road with a slope such as an uphill or downhill slope.The control device 1 then outputs the maximum of the minimum rate value and the value obtained by applying a low-pass filter and margin addition to the longitudinal acceleration sensor value as the rate value.

[0029] In this way, the rate value is calculated by performing rate limit processing on the longitudinal acceleration, which is the sensor value, so that the estimated vehicle speed obtained by integrating the rate value can be prevented from containing sudden fluctuation components.

[0030] FIG. 6 shows a graph (top) of the time history of wheel speed and vehicle speed, and a graph (bottom) of the time history of longitudinal acceleration when a vehicle slips while accelerating on a road surface with a low friction coefficient. The top graph is the same as the top graph of FIG. 4. The bottom graph shows the sensor value detected by the longitudinal acceleration sensor 22 as a thin dashed line, the sensor value after passing through the low-pass filter as a thin solid line, the aforementioned margin as a diagonal line, the minimum value of the aforementioned rate value as a dashed line, the finally calculated rate value as a thick solid line, and the actual longitudinal acceleration of the vehicle as a thick dashed line. Note that FIG. 6 shows a case where the estimated vehicle speed is calculated using the rate limiting process based on FIG. 5, i.e., the cutoff frequency of the low-pass filter is set to 1.0 Hz.

[0031] As shown in FIG. 6, the sensor value of the longitudinal acceleration increases significantly at time t1. This is because the vehicle entered a slip state at time t1, causing the sensor value of the longitudinal acceleration to increase due to pitching of the vehicle (i.e., tilting of the vehicle in the longitudinal direction). Although the sensor value of the longitudinal acceleration increases significantly, the vehicle is in a slip state and the wheels are spinning, so the actual acceleration of the vehicle body in the longitudinal direction does not increase significantly. This increase in the sensor value of the longitudinal acceleration due to pitching is one of the causes of the discrepancy between the rate value and the actual acceleration of the vehicle body, and in this case, the estimated vehicle speed calculated by integrating the rate value will be higher than the actual vehicle speed.

[0032] Therefore, when it is determined that the vehicle has slipped during acceleration, the control device 1 switches the mode of rate limiting processing. Specifically, when it is determined that the vehicle has slipped during acceleration, the control device 1 switches the rate limiting processing to a mode that suppresses the influence of longitudinal acceleration caused by pitching of the vehicle.

[0033] Specifically, as shown in FIG. 7, when the control device 1 determines that the vehicle has entered a slip state during acceleration, it changes the cutoff frequency of the low-pass filter from 1.0 Hz to 0.1 Hz and performs a filtering process to attenuate (remove) frequency components of 0.1 Hz or higher contained in the detected longitudinal acceleration. By lowering the cutoff frequency, as shown in FIG. 8, the control device 1 can calculate a rate value in which the increase in the sensor value caused by pitching has been attenuated. Therefore, compared to when the cutoff frequency is set to 1.0 Hz, the rate value can be made closer to the actual acceleration of the vehicle body, improving the calculation accuracy of the estimated vehicle body speed when the vehicle is in a slip state. As a result, the control device 1 can appropriately control the driving state of the vehicle.

[0034] Furthermore, as shown in Fig. 6, when the vehicle is in a slip state, the margin added to the longitudinal acceleration sensor value is also one of the causes of the discrepancy between the rate value and the actual acceleration of the vehicle body. Therefore, as shown in Fig. 7, when it is determined that the vehicle is in a slip state during acceleration, the control device 1 performs offset processing to cancel the addition of the margin. This allows the rate value calculated by the rate limit processing to be closer to the actual acceleration of the vehicle body, as shown in Fig. 8, and improves the calculation accuracy of the estimated vehicle body speed when the vehicle is in a slip state.

[0035] In addition to the process of canceling the margin, the offset process may also include a process of 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 of learning the sensor value deviation from the detection result of the longitudinal acceleration sensor 22 detected every time the vehicle is stopped, and canceling the sensor value deviation from the acceleration detected when the vehicle is accelerating. This allows the acceleration detected by the acceleration sensor to approach the actual acceleration of the vehicle body.

[0036] 9 shows an example of a control flow executed by the control device 1. The control device 1 receives detection results from the wheel speed sensor 21 and the longitudinal acceleration sensor 22, and acquires the wheel speed and longitudinal acceleration (step S1). The control device 1 calculates a base vehicle speed based on the acquired wheel speeds (step S2).

[0037] Next, the control device 1 performs rate limiting on the acquired longitudinal acceleration (step S3). At this time, if it is determined that the vehicle is not in a slip state, the control device 1 performs rate limiting with the cutoff frequency of the low-pass filter for the rate limiting set to the normal value of 1.0 Hz. Then, the control device 1 calculates an estimated vehicle speed based on the rate value obtained by the rate limiting (step S4).

[0038] Next, the control device 1 determines whether the base vehicle speed is greater than the estimated vehicle speed (step S5). If the control device 1 determines that 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 in a slip state, i.e., is in a grip state (step S6), and sets the cutoff frequency of the low-pass filter to 1.0 Hz (step S7). On the other hand, if the control device 1 determines that the base vehicle speed is greater than the estimated vehicle speed (step S5; YES), the control device 1 determines that the vehicle is in a slip state (step S8), and sets the cutoff frequency of the low-pass filter to 0.1 Hz (step S9).

[0039] In the above explanation, the control device 1 calculates the estimated vehicle speed based on the detection results of the longitudinal acceleration sensor 22. However, if an abnormality (failure) of the longitudinal acceleration sensor 22 is detected, it is possible to consider a configuration in which the rate value is calculated based on the total driving force of the vehicle without using the detection results of the longitudinal acceleration sensor 22.

[0040] FIG. 10 is a block diagram showing an example of rate limiting processing when an abnormality is detected in the longitudinal acceleration sensor 22 and it is determined that the vehicle is not in a slipping state. In this case, the control device 1 uses the total driving force of the vehicle as an input value for the rate limiting processing. More specifically, the control device 1 calculates the longitudinal acceleration converted from the total driving force and vehicle weight (also referred to as converted longitudinal acceleration) by subtracting the rolling resistance and air resistance of the vehicle from the total driving force and dividing the result by the vehicle weight. Furthermore, when the vehicle is stopped, the control device 1 sets the converted longitudinal acceleration to zero. Note that the vehicle weight may be the weight of the vehicle itself, or may be a weight that takes into account the weight of the occupants in advance.

[0041] The control device 1 does not perform filtering processing using a low-pass filter on the converted longitudinal acceleration, but 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 rate value as the rate value, and calculates the estimated vehicle speed based on the rate value.

[0042] On the other hand, when an abnormality is detected in the longitudinal acceleration sensor 22 and it is determined that the vehicle is in a slip state, the control device 1 uses a fixed value prepared in advance as the rate value. The fixed value is, for example, an acceleration equivalent to that on a frozen road surface (for example, 0.007 to 0.01 m / s 2 The control device 1 calculates the estimated vehicle speed based on the rate value, which is a fixed value.

[0043] In this way, even if an abnormality is detected in the longitudinal acceleration sensor 22 and an appropriate sensor value of the longitudinal acceleration cannot be acquired, the control device 1 can calculate the rate value and, as a result, the estimated vehicle speed.

[0044] In addition, the control device 1 may determine that there is an abnormality in the longitudinal acceleration sensor 22 when, for example, a failure signal is acquired from the longitudinal acceleration sensor 22, or may determine that there is an abnormality in the longitudinal acceleration sensor 22 when the detection value of the longitudinal acceleration sensor 22 exceeds an abnormality determination threshold.

[0045] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any manner without departing from the spirit of the invention.

[0046] For example, in the above embodiment, the control by the control device 1 when the vehicle is accelerating has been described as an example, but the present invention is not limited to this, and similar control can also be performed when the vehicle is decelerating.

[0047] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0048] (1) a wheel speed acquisition unit (wheel speed acquisition unit 11) that acquires wheel speeds of a plurality of wheels of a vehicle from detection results of a wheel speed sensor (wheel speed sensor 21); an acceleration acquisition unit (longitudinal acceleration acquisition unit 12) that acquires the acceleration of the vehicle in the longitudinal direction from the detection result of an acceleration sensor (longitudinal acceleration sensor 22); a calculation unit (base vehicle speed calculation unit 13) that calculates a first vehicle speed (base vehicle speed) of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors; an estimation unit (vehicle speed estimation unit 14) that calculates a second vehicle speed (estimated vehicle speed) that is an estimated value of the vehicle speed of the vehicle based on the first vehicle speed and the acceleration detected by the acceleration sensor; A vehicle control device (vehicle control device 1) including a slip determination unit (slip determination unit 15) that determines whether the vehicle is in a slip state, The estimation unit calculating the second vehicle speed by performing a predetermined limit process on the acceleration detected by the acceleration sensor; when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the mode of the limit processing is switched. Vehicle control device.

[0049] According to (1), when the vehicle slips during acceleration or deceleration, the mode of limit processing performed on the detected acceleration is switched, thereby improving the accuracy of calculating the second vehicle speed (estimated vehicle speed) when the vehicle is slipping.

[0050] (2) The vehicle control device according to (1), the limiting process includes a filtering process of reducing frequency components of the acceleration detected by the acceleration sensor that are equal to or greater than a predetermined threshold value, The estimation unit When it is determined that the vehicle is not in the slip state during acceleration or deceleration of the vehicle, the predetermined threshold is set to a first threshold (1.0 Hz); When it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the predetermined threshold is set to a second threshold (0.1 Hz) that is lower than the first threshold. Vehicle control device.

[0051] According to (2), when it is determined that the vehicle has entered a slip state during acceleration or deceleration, the predetermined threshold value for the filtering process is set to a second threshold value that is lower than the first threshold value, thereby suppressing the effects of acceleration caused by pitching of the vehicle.

[0052] (3) The vehicle control device according to (1) or (2), The slip determination unit If at least one wheel is in a state of gripping the road surface, it is determined that the vehicle is not in the slip state; If all of the wheels are not gripping the road surface, the vehicle is determined to be in the slip state. Vehicle control device.

[0053] According to (3), the slip state can be appropriately determined according to the state of the wheels.

[0054] (4) A vehicle control device according to any one of (1) to (3), When the vehicle accelerates, the calculation unit calculates a minimum wheel speed among the wheel speeds of the plurality of wheels as the first vehicle body speed. Vehicle control device.

[0055] According to (4), when the vehicle is accelerating, the first vehicle speed can be made close to the actual vehicle speed.

[0056] (5) The vehicle control device according to (4), The slip determination unit If the second vehicle speed is greater than the first vehicle speed, it is determined that the vehicle is in the slip state; If the second vehicle speed is substantially the same as the first vehicle speed, it is determined that the vehicle is not in the slip state. Vehicle control device.

[0057] 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.

[0058] (6) A vehicle control device according to any one of (1) to (5), 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. Vehicle control device.

[0059] According to (6), the acceleration detected by the acceleration sensor can be made closer to the actual acceleration of the vehicle, thereby further improving the accuracy of calculating the second vehicle body speed when the vehicle is in a slipping state.

[0060] (7) A vehicle control device according to any one of (1) to (6), Further, a drive control unit (drive control unit 16) is provided to control the drive state of the vehicle. The drive control unit controls the drive state based on the second vehicle body speed. Vehicle control device.

[0061] According to (7), the second vehicle body speed is highly accurate even when the vehicle is in a slipping state, so that the driving state of the vehicle can be appropriately controlled when the vehicle is in a slipping state.

[0062] (8) The vehicle control device according to (7), the vehicle is an all-wheel drive vehicle; the drive control unit controls a drive force distribution to a plurality of wheels of the vehicle based on the second vehicle body speed. Vehicle control device.

[0063] According to (8), the second vehicle speed is highly accurate even when the vehicle is in a slipping state, so that the distribution of driving force to the plurality of wheels can be appropriately controlled when the vehicle is in a slipping state.

[0064] (9) A vehicle control device according to any one of (1) to (8), when it is determined that the vehicle has entered the slip state during acceleration or deceleration of the vehicle, the estimation unit switches the limit process to a mode that suppresses the effect of the acceleration caused by pitching of the vehicle. Vehicle control device.

[0065] According to (9), when the vehicle slips during acceleration or deceleration, the limit processing performed on the detected acceleration is switched to a mode that suppresses the influence of acceleration caused by pitching of the vehicle, thereby improving the calculation accuracy of the second vehicle speed (estimated value of vehicle speed) when the vehicle is in a slip state.

[0066] (10) A vehicle control device according to any one of (1) to (9), the estimation unit detects an abnormality in the acceleration sensor, and when it is determined that the vehicle has entered the slip state during acceleration or deceleration of the vehicle, calculates the second vehicle body speed based on acceleration that is a fixed value prepared in advance. Vehicle control device.

[0067] According to (10), even when an abnormality occurs in the acceleration sensor, the second vehicle speed can be calculated appropriately. [Explanation of symbols]

[0068] 1 Vehicle control device 11 Wheel speed acquisition section 12 Longitudinal acceleration acquisition section (acceleration acquisition section) 13 Base vehicle speed calculation unit (calculation unit) 14 Vehicle speed estimation unit (estimation unit) 15 Slip determination section 16 Drive control unit 21 Wheel speed sensor 22 Front and rear acceleration sensor (acceleration sensor)

Claims

1. a wheel speed acquisition unit that acquires wheel speeds of a plurality of wheels of a vehicle from detection results of wheel speed sensors; an acceleration acquisition unit that acquires acceleration in the front-rear direction of the vehicle from a detection result of an acceleration sensor; a calculation unit that calculates a first vehicle speed of the vehicle based on the wheel speeds of the plurality of wheels detected by the wheel speed sensors; an estimation unit that calculates a second vehicle speed that is an estimated value of the vehicle speed of the vehicle based on the first vehicle speed and the acceleration detected by the acceleration sensor; a slip determination unit that determines whether the vehicle is in a slip state, The estimation unit calculating the second vehicle speed by performing a predetermined limit process on the acceleration detected by the acceleration sensor; when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the mode of the limit processing is switched. Vehicle control device.

2. The vehicle control device according to claim 1, the limiting process includes a filtering process of reducing frequency components of the acceleration detected by the acceleration sensor that are equal to or greater than a predetermined threshold value, The estimation unit When it is determined that the vehicle is not in the slip state during acceleration or deceleration of the vehicle, the predetermined threshold value is set to a first threshold value; When it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the predetermined threshold is set to a second threshold that is lower than the first threshold. Vehicle control device.

3. The vehicle control device according to claim 1, The slip determination unit If at least one wheel is in a state of gripping the road surface, it is determined that the vehicle is not in the slip state; If all of the wheels are not gripping the road surface, the vehicle is determined to be in the slip state. Vehicle control device.

4. The vehicle control device according to claim 1, 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. Vehicle control device.

5. The vehicle control device according to claim 4, The slip determination unit If the second vehicle speed is greater than the first vehicle speed, it is determined that the vehicle is in the slip state; If the second vehicle body speed is substantially the same as the first vehicle body speed, it is determined that the vehicle is not in the slip state. Vehicle control device.

6. The vehicle control device according to claim 1, 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. Vehicle control device.

7. The vehicle control device according to claim 1, a drive control unit that controls a drive state of the vehicle; the drive control unit controls the drive state based on the second vehicle body speed. Vehicle control device.

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

9. 9. A vehicle control device according to claim 1, when it is determined that the vehicle has entered the slip state during acceleration or deceleration of the vehicle, the estimation unit switches the limit process to a mode that suppresses the effect of the acceleration caused by pitching of the vehicle. Vehicle control device.

10. 9. A vehicle control device according to claim 1, the estimation unit detects an abnormality in the acceleration sensor, and when it is determined that the vehicle has entered the slip state during acceleration or deceleration of the vehicle, calculates the second vehicle body speed based on acceleration that is a fixed value prepared in advance. Vehicle control device.

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