Vehicle control device

Abstract

Provided is a vehicle control device capable of improving the calculation accuracy of an estimated value of the vehicle body speed when the vehicle is in a slip state. 【Solution means】The vehicle control device 1 includes a base vehicle body speed calculation unit 13 that calculates a base vehicle body speed based on the wheel speeds of a plurality of vehicle wheels detected by a wheel speed sensor 21, a vehicle body speed estimation unit 14 that calculates an estimated vehicle body speed based on the base vehicle body speed and the longitudinal and lateral acceleration detected by a longitudinal and lateral 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 a predetermined limit process on the longitudinal and lateral acceleration, and switches the mode of the limit process when it is determined that the vehicle is in a slip state during acceleration or deceleration of the vehicle.

Description

Technical Field

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

Background Art

[0002] In recent years, efforts have been actively made to provide access to a sustainable transportation system that takes into account people in vulnerable positions among traffic participants. Toward this realization, research and development have focused on further improving traffic safety and convenience through research and development related to driving support.

[0003] For example, Patent Documents 1 to 3 disclose devices that estimate vehicle speed based on detection results of wheel speed sensors and front and rear acceleration sensors provided in a vehicle, and use the estimated vehicle speed for various controls including driving support of the vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the vehicle is in a slip state, a deviation occurs between the detection result of the front and rear acceleration sensor and the actual acceleration of the vehicle body due to pitching of the vehicle, and there is a possibility that the vehicle speed (estimated vehicle body speed) estimated based on the front and rear acceleration sensor is not high. Since appropriate vehicle control for a slip state requires a highly accurate estimated vehicle body speed, there has been room for improvement in improving the calculation accuracy of the estimated vehicle body speed.

[0006] The present invention provides a vehicle control device capable of improving the calculation accuracy of an estimated value of the vehicle body speed when the vehicle is in a slip state.

Means for Solving the Problems

[0007] The present invention a wheel speed acquisition unit that acquires the wheel speeds of a plurality of wheels of the vehicle from the detection results of wheel speed sensors; an acceleration acquisition unit that acquires the acceleration in the longitudinal direction of the vehicle from the detection results of an 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 estimation unit that calculates a second vehicle body speed, which is an estimated value of the vehicle body speed of the vehicle, based on the first vehicle body speed and the acceleration detected by the acceleration sensor; a slip determination unit that determines whether or not the vehicle is in a slip state, and a vehicle control device comprising: the estimation unit calculates the second vehicle body speed by performing a predetermined limit process on the acceleration detected by the acceleration sensor, and switches the mode of the limit process when it is determined that the vehicle has entered the slip state during acceleration or deceleration of the vehicle.

Advantages of the Invention

[0008] 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 slip state.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out 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 an embodiment of the present invention. The control device 1 is mounted on a vehicle such as a four-wheeled vehicle, for example. An internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, or a combination thereof is used as a drive source for the vehicle. The vehicle is, for example, a four-wheel drive vehicle in which the rotational force generated by the drive source is distributed to the front and rear wheels. The control device 1 controls the drive force distribution of each wheel of the four-wheel drive vehicle.

[0011] The control device 1 communicates with the vehicle sensor 2 mounted on the vehicle and receives signals indicating various types of information from the vehicle sensor 2. The control device 1 is configured as a computer including a control arithmetic unit, a storage device, and an input / output device as a physical configuration. The control arithmetic unit is an ECU (Electronic Control Unit) constituted by a controller such as a CPU (Central Processing Unit), for example, and executes arithmetic processing and controls the storage device and the input / output device. The storage device has, for example, a main storage device and an auxiliary storage device. The main storage device is constituted by, for example, a RAM (Random Access Memory). Further, the auxiliary storage device is constituted by, for example, a ROM (Read Only Memory). The input / output device has, for example, an input device that inputs data from the outside and transmits it to the storage device, and an output device that outputs, for example, the arithmetic result calculated by the control arithmetic unit and stored in the storage device to the outside.

[0012] The control device 1 executes the processing of the control flow described later, for example, by reading a program stored in the ROM into the RAM and executing the program read into the RAM by the CPU. Note that the control device 1 may physically have a configuration different from the above-described configuration.

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

[0014] 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 and lateral 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 a signal from the wheel speed sensor 21 and acquires the wheel speeds of a plurality of wheels. The longitudinal and lateral acceleration acquisition unit 12 receives a signal from the longitudinal and lateral acceleration sensor 22 and acquires the longitudinal and lateral 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 sensor 21. FIG. 2 is a block diagram for explaining the calculation of the base vehicle body speed. The wheel speeds of each wheel detected by the wheel speed sensor 21 and the longitudinal and lateral acceleration detected by the longitudinal and lateral acceleration sensor 22 are input to the base vehicle body speed calculation unit 13. In the present embodiment, when the vehicle is accelerating, the base vehicle body speed calculation unit 13 uses the minimum wheel speed among the wheel speeds of the plurality of wheels as the base vehicle body speed. On the other hand, when the vehicle is decelerating, the base vehicle body speed calculation unit 13 uses the maximum wheel speed among the wheel speeds of the plurality of wheels as the base vehicle body speed.

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

[0018] 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 base vehicle body speed and the estimated vehicle body speed.

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

[0020] In the upper graph of FIG. 4, the wheel speeds of all the wheels are greater than the actual vehicle body speed. The base vehicle body speed calculation unit 13 calculates the wheel speed of the right rear wheel RR, which is the minimum wheel speed, as the base vehicle body speed, and the vehicle body speed estimation unit 14 integrates the longitudinal acceleration detected by the longitudinal acceleration acquisition unit 12 after rate limiting processing to calculate the estimated vehicle body speed. The slip determination unit 15 compares the base vehicle body speed with the estimated vehicle body speed, and if it determines that the base vehicle body speed is greater than the estimated vehicle body speed, it determines that the vehicle is in the slip state.

[0021] In the lower graph of FIG. 4, the wheel speeds of the right front wheel FR, the left front wheel FL, and the left rear wheel RL are spinning and greater than the actual vehicle body speed, but the right rear wheel RR is gripping the road surface, and the wheel speed of the right rear wheel RR is substantially the same as the actual vehicle body speed. The base vehicle body speed calculation unit 13 calculates the wheel speed of the right rear wheel RR, which is the minimum wheel speed, as the base vehicle body speed, and the vehicle body speed estimation unit 14 integrates the longitudinal acceleration detected by the longitudinal acceleration sensor 22 after rate limiting processing to calculate the estimated vehicle body speed. The slip determination unit 15 compares the base vehicle body speed with the estimated vehicle body speed, and if it determines that the base vehicle body speed is substantially the same as the estimated vehicle body speed, it determines that the vehicle is not in the slip state.

[0022] Note that 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 obtained by communication with the outside of the vehicle, distortion information of the vehicle chassis, and the like.

[0023] Returning to FIG. 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 estimation unit 14. Specifically, when the vehicle is an all-wheel drive vehicle, the drive force distribution of a plurality of wheels is controlled based on the estimated vehicle body speed.

[0024] Subsequently, the details of the rate limit process executed by the vehicle body speed estimation unit 14 will be described.

[0025] FIG. 5 is a block diagram for explaining the rate limit process by the vehicle body speed estimation unit 14 when the vehicle is in a grip state. When the vehicle is not in a slip state, the control device 1 calculates the estimated vehicle body speed based on the rate limit process of FIG. 5 until it is determined that the vehicle is in a slip state. Then, when it is determined that the vehicle has entered a slip state, the control device 1 switches to the rate limit process of FIG. 7 described later.

[0026] As shown in FIG. 5, the control device 1 applies a low-pass filter (also referred to as LPF in the figure) to the longitudinal and lateral acceleration, which is the sensor value detected by the longitudinal and lateral acceleration sensor 22, and performs a filtering process to decrease (remove) frequency components above a predetermined threshold value included in the sensor value. For example, the control device 1 sets a predetermined threshold value, that is, a cut-off frequency, to 1.0 Hz, for example, and can reduce the noise included in the sensor value by decreasing the frequency components of 1.0 Hz or higher included in the sensor value.

[0027] In addition, the control device 1 adds a predetermined margin to the longitudinal and lateral acceleration after the low-pass filter. The addition of the margin takes into account the sensor value deviation of the longitudinal and lateral acceleration sensor 22.

[0028] Furthermore, as a countermeasure when the longitudinal acceleration is canceled out on a sloped road such as an uphill or downhill road, the control device 1 sets the minimum value of the rate value. Then, the control device 1 outputs the maximum value between the value obtained by applying a low-pass filter and margin addition to the sensor value of the longitudinal acceleration and the minimum value of the rate value as the rate value.

[0029] In this way, since rate limit processing is performed on the longitudinal acceleration which is a sensor value to calculate the rate value, it is possible to suppress the inclusion of a rapid fluctuation component in the estimated vehicle body speed obtained by integrating the rate value.

[0030] FIG. 6 shows a graph of the time history of the wheel speed and the vehicle body speed (upper side), and a graph of the time history of the longitudinal acceleration (lower side) when the vehicle is in a slip state when accelerating on a road surface with a low friction coefficient, for example. The upper graph is the same graph as the upper graph of FIG. 4. In the lower graph, the sensor value detected by the longitudinal acceleration sensor 22 is shown as a thin dashed line, the sensor value after applying a low-pass filter is shown as a thin solid line, the aforementioned margin is shown as a hatched area, the aforementioned minimum value of the rate value is shown as a one-dot chain line, the finally calculated rate value is shown as a thick solid line, and the actual longitudinal acceleration of the vehicle is shown as a thick dashed line. Note that FIG. 6 shows the case where the estimated vehicle body speed is calculated by the rate limit processing based on FIG. 5, that is, the cut-off 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 at time t1, as a result of the vehicle being in a slip state, the sensor value of the longitudinal acceleration increases due to pitching of the vehicle (i.e., the inclination of the vehicle in the longitudinal direction). Although the sensor value of the longitudinal acceleration increases significantly, since the vehicle is in a slip state and the wheels are spinning, the actual acceleration of the vehicle body in the longitudinal direction does not increase significantly. The increase in the sensor value of the longitudinal acceleration due to this pitching is one of the causes of the deviation between the rate value and the actual acceleration of the vehicle body. In this case, the estimated vehicle speed calculated by integrating the rate value will be larger than the actual vehicle speed.

[0032] Therefore, when it is determined that the vehicle is in a slip state during acceleration, the control device 1 switches the mode of the rate limit process. Specifically, when it is determined that the vehicle is in a slip state during acceleration, the control device 1 switches the rate limit process to a mode that suppresses the influence of the longitudinal acceleration caused by the pitching of the vehicle.

[0033] Specifically, as shown in FIG. 7, when it is determined that the vehicle is in a slip state during acceleration, the control device 1 changes the cut-off frequency of the low-pass filter from 1.0 Hz to 0.1 Hz and performs filtering processing to attenuate (remove) the frequency components of 0.1 Hz or higher included in the detected longitudinal acceleration. By decreasing the cut-off frequency, as shown in FIG. 8, the control device 1 can calculate a rate value with the increase in the sensor value due to pitching attenuated. Therefore, compared with the case where the cut-off frequency is set to 1.0 Hz, the rate value can be made closer to the actual acceleration of the vehicle body, and the calculation accuracy of the estimated vehicle speed when the vehicle is in a slip state can be improved. As a result, the control device 1 can appropriately control the driving state of the vehicle.

[0034] Also, as shown in FIG. 6, when the vehicle is in a slip state, the margin added to the sensor values of the longitudinal and lateral accelerations is also one of the causes of the deviation between the rate value and the actual vehicle body acceleration. 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 an offset process to cancel the addition of the margin. As a result, as shown in FIG. 8, the rate value calculated by the rate limit process can be brought closer to the actual vehicle body acceleration, and the calculation accuracy of the estimated vehicle body speed when the vehicle is in a slip state can be improved.

[0035] Note that the offset process may include, in addition to the process of canceling the margin, a process of canceling the longitudinal and lateral accelerations detected when the vehicle is stopped from the accelerations detected when the vehicle is accelerating. Specifically, the control device 1 may learn the sensor value deviation from the detection results of the longitudinal and lateral acceleration sensor 22 detected each time the vehicle stops, and include a process of canceling the sensor value deviation from the accelerations detected when the vehicle is accelerating. Thereby, the acceleration detected by the acceleration sensor can be made closer to the actual vehicle body acceleration.

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

[0037] Next, the control device 1 performs a rate limit process on the acquired longitudinal and lateral accelerations (step S3). At this time, if it is not in a state determined to be a slip state, the control device 1 performs the rate limit process with the cut-off frequency of the low-pass filter of the rate limit process set to the normal value of 1.0 Hz. Then, the control device 1 calculates an estimated vehicle body speed based on the rate value obtained by the rate limit process (step S4).

[0038] Next, the control device 1 determines whether the base vehicle speed is greater than the estimated vehicle speed (step S5). When it is determined that the base vehicle speed is not greater than the estimated vehicle speed and is substantially the same (step S5; NO), the control device 1 determines that the vehicle is not in a slip state, that is, in a grip state (step S6), and sets the cut-off frequency of the low-pass filter to 1.0 Hz (step S7). On the other hand, when it is determined that the base vehicle speed is greater than the estimated vehicle speed (step S5; YES), the control device 1 determines that the vehicle has entered a slip state (step S8), and sets the cut-off frequency of the low-pass filter to 0.1 Hz (step S9).

[0039] In the above description, the control device 1 calculates the estimated vehicle speed based on the detection result of the longitudinal acceleration sensor 22. However, when an abnormality (failure) of the longitudinal acceleration sensor 22 is detected, a configuration may be considered in which the rate value is calculated based on the total driving force of the vehicle without using the detection result of the longitudinal acceleration sensor 22.

[0040] FIG. 10 is a block diagram showing an example of rate limit processing when it is determined that the vehicle is not in a slip state when an abnormality of the longitudinal acceleration sensor 22 is detected. In this case, the control device 1 uses the total driving force of the vehicle as the input value for the rate limit processing. More specifically, the control device 1 calculates the longitudinal acceleration (also referred to as the converted longitudinal acceleration) converted from the total driving force and the vehicle weight by dividing the value obtained by subtracting the rolling resistance and air resistance of the vehicle from the total driving force by the vehicle weight. Also, 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 a weight that takes into account the weight of the passengers in advance.

[0041] The control device 1 does not perform filtering processing on the converted longitudinal acceleration by a low-pass filter, but adds a margin to the converted longitudinal acceleration. Then, the control device 1 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 of the longitudinal acceleration sensor 22 is detected and it is determined that the vehicle is in a slip state, the control device 1 uses a previously prepared fixed value as the rate value. The fixed value is, for example, an acceleration equivalent to an icy road surface (e.g., about 0.007 to 0.01 m / s 2 ²). The control device 1 calculates the estimated vehicle body speed based on the rate value which is the fixed value.

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

[0044] Note that the control device 1 may determine the abnormality of the longitudinal acceleration sensor 22 when, for example, it acquires a failure signal from the longitudinal acceleration sensor 22, or may determine the abnormality of the longitudinal acceleration sensor 22 when the detected value of the longitudinal acceleration sensor 22 exceeds the abnormality determination threshold value.

[0045] As described above, an embodiment of the present invention has been described with reference to the accompanying drawings. Needless to say, the present invention is not limited to such an embodiment. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Also, within the scope not departing from the gist of the invention, the components in the above embodiment may be arbitrarily combined.

[0046] For example, in the above-described embodiment, the control by the control device 1 during the acceleration running of the vehicle has been described as an example, but the present invention is not limited thereto, and the same control can be performed during the deceleration running of the vehicle.

[0047] At least the following matters are described in this specification. Although the corresponding components etc. in the above-described embodiment are shown as examples in the parentheses, the present invention is not limited thereto.

[0048] (1) A wheel speed acquisition unit (wheel speed acquisition unit 11) that acquires the wheel speeds of a plurality of vehicle wheels from the detection results of a wheel speed sensor (wheel speed sensor 21), An acceleration acquisition unit (longitudinal acceleration acquisition unit 12) that acquires the longitudinal acceleration of the vehicle from the detection results of an acceleration sensor (longitudinal and lateral acceleration sensor 22), A calculation unit (base vehicle body speed calculation unit 13) that calculates a first vehicle body speed (base vehicle body speed) of the vehicle based on the wheel speeds of the plurality of vehicle wheels detected by the wheel speed sensor, An estimation unit (vehicle body speed estimation unit 14) that calculates a second vehicle body speed (estimated vehicle body speed), which is an estimated value of the vehicle body speed of the vehicle, based on the first vehicle body speed and the acceleration detected by the acceleration sensor, A slip determination unit (slip determination unit 15) that determines whether or not the vehicle is in a slip state, and a vehicle control device (vehicle control device 1) comprising: The estimation unit: Calculates the second vehicle body 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, switches the mode of the limit process. Vehicle control device.

[0049] According to (1), when the vehicle is in a slip state during acceleration or deceleration of the vehicle, the mode of the limit process performed on the detected acceleration is switched, so that the calculation accuracy of the second vehicle body speed (estimated value of the vehicle body speed) in the slip state of the vehicle can be improved.

[0050] (2) The vehicle control device according to (1), The limit process includes a filtering process that reduces 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, sets the predetermined threshold value to a first threshold value (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 value is set to a second threshold value (0.1 Hz) lower than the first threshold value. Vehicle control device.

[0051] According to (2), when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, the predetermined threshold value of the filtering process is set to a second threshold value lower than the first threshold value, so that the influence of the acceleration caused by the pitching of the vehicle can be suppressed.

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

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

[0054] (4) The vehicle control device according to any one of (1) to (3), during acceleration of the vehicle, the calculation unit calculates the 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), during acceleration of the vehicle, the first vehicle body speed can be made close to the actual vehicle body speed.

[0056] (5) The vehicle control device according to (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. Vehicle control device.

[0057] According to (5), based on the first vehicle speed based on the detected wheel speed and the second vehicle speed based on the detected acceleration, the slip state can be appropriately determined.

[0058] (6) The vehicle control device according to any one of (1) to (5), The limit process includes a process of canceling the acceleration detected when the vehicle stops from the acceleration detected when the vehicle accelerates or decelerates. Vehicle control device.

[0059] According to (6), since the acceleration detected by the acceleration sensor can be made closer to the actual vehicle acceleration, the calculation accuracy of the second vehicle speed in the slip state of the vehicle can be further improved.

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

[0061] According to (7), since the accuracy of the second vehicle speed is high even in the slip state of the vehicle, the drive state of the vehicle can be appropriately controlled in the slip state.

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

[0063] According to (8), since the accuracy of the second vehicle speed is high even in the slip state of the vehicle, the drive force distribution to a plurality of wheels can be appropriately controlled in the slip state.

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

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

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

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

Explanation of Signs

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

Claims

1. A wheel speed acquisition unit that acquires the wheel speeds of a plurality of vehicle wheels from the detection results of a wheel speed sensor; An acceleration acquisition unit that acquires the acceleration in the longitudinal direction of the vehicle from the detection results of an 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 sensor; An estimation unit that calculates a second vehicle body speed, which is an estimated value of the vehicle body speed of the vehicle, based on the first vehicle body speed and the acceleration detected by the acceleration sensor; A vehicle control device comprising a slip determination unit that determines whether or not the vehicle is in a slip state, wherein the estimation unit calculates the second vehicle body speed by performing a predetermined limit process on the acceleration detected by the acceleration sensor, and when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle, switches the mode of the limit process. Vehicle control device.

2. The vehicle control device according to claim 1, wherein the limit process includes a filtering process that reduces the frequency components of the acceleration detected by the acceleration sensor that are equal to or higher than a predetermined threshold value, and the estimation unit sets the predetermined threshold value to a first threshold value when it is determined that the vehicle is not in the slip state during acceleration or deceleration of the vehicle, and sets the predetermined threshold value to a second threshold value lower than the first threshold value when it is determined that the vehicle is in the slip state during acceleration or deceleration of the vehicle. Vehicle control device.

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 in a state of gripping the road surface, and determines that the vehicle is in the slip state when all wheels are not in a state of gripping the road surface. Vehicle control device.

4. The vehicle control device according to claim 1, wherein during acceleration of the vehicle, the calculation unit calculates the 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, 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. Vehicle control device.

6. The vehicle control device according to claim 1, wherein The limit processing 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. **Claim 7** The vehicle control device according to claim 1, further comprising a drive control unit that controls a drive state of the vehicle, wherein the drive control unit controls the drive state based on the second vehicle body speed. Vehicle control device. **Claim 8** The vehicle control device according to claim 7, wherein the vehicle is an all-wheel drive vehicle, and 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. **Claim 9** The vehicle control device according to any one of claims 1 to 8, wherein when the estimation unit determines that the vehicle is in a slip state during acceleration or deceleration of the vehicle, the limit processing is switched to a mode that suppresses the influence of the acceleration caused by pitching of the vehicle. Vehicle control device. **Claim 10** The vehicle control device according to any one of claims 1 to 8, wherein the estimation unit detects an abnormality of the acceleration sensor, and when it is determined that the vehicle is in a slip state during acceleration or deceleration of the vehicle, calculates the second vehicle body speed based on an acceleration that is a fixed value prepared in advance. Vehicle control device.

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