JP2008207678A - Vehicular control device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a vehicle behavior from being unstable when a ground speed sensor is determined to be abnormal. <P>SOLUTION: A vehicular control device has a first vehicle body speed estimation part 3 which obtains a first estimated vehicle body speed according to a wheel speed given by an output signal from a wheel speed sensor; a ground speed sensor failure detection part 6 which detects the abnormal state of the ground speed sensor; a second vehicle body speed estimation part 5 which obtains a second estimated vehicle body speed according to a vehicle body speed given by an output signal from the ground speed sensor, the first estimated vehicle body speed and the abnormal state of the ground speed sensor; an estimated vehicle body speed selection part 7 which selects an estimated vehicle body speed used for vehicle control; and a vehicular control selection part 10 which selects either a first vehicular control part 8 which controls a vehicle according to the abnormal state of the ground speed sensor, the vehicle body speed and the wheel speed, or a second vehicular control part 9 which controls the vehicle according to the estimated vehicle body speed selected by the estimated vehicle body speed selection part 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus and control method using a ground speed sensor.

  In order to suppress the increase in the number of vehicle accidents in recent years, research and development of preventive safety technology to prevent accidents such as vehicle collision prevention devices, ABS (Anti-lock Brake System), and vehicle skid prevention devices has been promoted by each manufacturer. .

  In vehicle collision prevention devices, ABSs, vehicle skid prevention devices, etc., the wheel slip ratio obtained from the vehicle ground speed (hereinafter referred to as “body speed”) and the rotational speed of each wheel (hereinafter referred to as “wheel speed”) is calculated. The control is performed so as to be within an appropriate range according to the vehicle state. At this time, the vehicle body speed is obtained by estimating from the wheel speeds of the four wheels. The ground speed sensor that directly measures the body speed, and the vehicle control such as the ABS and the vehicle skid prevention device using the ground speed sensor. Systems are also being developed. Since the vehicle body speed is directly measured, the detection accuracy of the wheel slip ratio and the vehicle body slip angle is improved as compared with the conventional estimated vehicle body speed, so that the performance of the ABS and the vehicle skid prevention device is improved.

  However, in the case of a vehicle motion control system using such a ground speed sensor, if the ground speed sensor does not operate normally, the driver may be in a dangerous situation, for example, the braking force will not work or the vehicle will spin. There is sex. Therefore, the countermeasure processing when the ground speed sensor is abnormal is very important.

  Therefore, a wheel speed sensor, a vehicle speed estimation means for estimating the vehicle speed based on the output of the wheel speed sensor, a ground speed sensor, a vehicle speed detected by the ground speed sensor, and an estimation obtained by the vehicle speed estimation means Ground speed sensor abnormality detecting means for detecting an abnormality of the ground speed sensor from the vehicle speed, first control means for performing ABS control based on the output of the vehicle speed and wheel speed sensor detected by the ground speed sensor, and the vehicle speed Second control means for performing ABS control based on the output of the estimated vehicle speed and wheel speed sensor obtained by the estimation means, and the first control means and the second control according to the output of the ground speed sensor abnormality detection means A selection means for selecting one of the means, and control based on the outputs of the ground speed sensor and the wheel speed sensor according to the normal or abnormal state of the ground speed sensor and the vehicle Method for selecting a control based on the speed estimation means and the wheel speed sensor is known (for example, see Patent Document 1).

JP 63-46961 A

  If an abnormality called a measurement error occurs between the output value of the ground speed sensor and the actual vehicle speed, using the output value of the ground speed sensor as it is for vehicle control will degrade the performance of the ABS, vehicle skid prevention device, etc. End up.

  Therefore, in the above known technique, when the ground speed sensor does not work normally, it is prohibited to use the output value of the ground speed sensor as the vehicle speed used in the control, and the estimated vehicle speed based on the wheel speed is switched, Further, the ABS control means is switched from the ABS control means based on the ground speed sensor output value and the wheel speed to the ABS control means based on the estimated vehicle speed based on the wheel speed and the wheel speed.

  However, there is a considerable discrepancy between the ground speed sensor output value when the ground speed sensor is normal and the estimated vehicle speed based on the wheel speed during ABS control based on the wheel speed and the ground speed sensor output value. Therefore, when the control vehicle speed is directly switched to the estimated vehicle speed based on the wheel speed at the moment when the ground speed sensor is determined to be abnormal as in the above-described known technology, the control vehicle speed changes in a stepwise manner. There was a problem that the behavior became unstable.

  The present invention has been made in view of the above points, and an object of the present invention is to suppress vehicle behavior from becoming unstable when the ground speed sensor is determined to be abnormal.

  A first vehicle control that determines an abnormal state of the ground speed sensor based on the wheel speed from the wheel speed sensor and a vehicle body speed from the ground speed sensor, and executes control of the vehicle based on the sensor value according to the abnormal state. Then, one of the second vehicle controls for executing vehicle control is selected based on the estimated vehicle body speed, and the braking force of each wheel is controlled based on the control command value calculated by the selected vehicle control.

  When the ground speed sensor is determined to be abnormal, it is possible to suppress the vehicle behavior from becoming unstable.

  An embodiment of the present invention will be described. The present embodiment relates to a brake control device for an automobile, for example, and relates to a brake control method when a sensor for measuring a ground speed of a vehicle does not normally operate during operation of an ABS, a vehicle skid prevention device, or the like.

  FIG. 1 is a functional block diagram of a vehicle control apparatus according to an embodiment of the present invention. FIG. 2 shows a time chart by the control by the control device of FIG.

  In FIG. 1, a wheel speed detection unit 1 detects a wheel speed from the rotational speed of the wheel. The ground speed sensor 2 detects a vehicle body speed that is a moving speed of the vehicle with respect to the road surface.

  The first vehicle body speed estimation unit 3 estimates the vehicle body speed, which is the moving speed of the vehicle with respect to the road surface in the front-rear direction of the vehicle, based on the wheel speed obtained by the wheel speed detection unit 1.

  The vehicle speed reference value calculation unit 4 calculates the vehicle speed reference value based on the vehicle speed detected by the ground speed sensor 2.

  The ground speed sensor abnormality detection unit 6 detects an abnormal state of the ground speed sensor 2 based on the vehicle speed detected by the ground speed sensor 2 and the vehicle speed reference value calculated by the vehicle speed reference value calculation unit 4.

  The second vehicle speed estimation unit 5 includes a vehicle speed detected by the ground speed sensor 2, a vehicle speed reference value calculated by the vehicle speed reference value calculation unit 4, and a wheel estimated by the first vehicle speed estimation unit 3. The vehicle body speed is estimated based on the first estimated vehicle body speed based on the speed and the abnormal state detected by the ground speed sensor abnormality detection unit 6.

  The estimated vehicle speed selector 7 includes a first estimated vehicle speed estimated by the first vehicle speed estimator 3 based on the wheel speed, a second estimated vehicle speed estimated by the second vehicle speed estimator 5, and wheels. Based on the wheel speed detected by the speed detection unit 1, an estimated vehicle body speed used in vehicle control is selected.

  The vehicle control unit 8 controls the vehicle based on the vehicle body speed detected by the ground speed sensor 2 and the wheel speed detected by the wheel speed detection unit 1.

  The vehicle control unit 9 is the first estimated vehicle speed based on the wheel speed estimated by the first vehicle speed estimation unit 3 selected by the estimated vehicle speed selection unit 7 or the first vehicle speed estimated by the second vehicle speed estimation unit 5. Control of the vehicle is executed based on one of the two estimated vehicle body speeds and the wheel speed detected by the wheel speed detector 1.

  The vehicle control selection unit 10 is based on an abnormal state detected by the ground speed sensor abnormality detection unit 6 among the vehicle control unit 8 based on the ground speed sensor value and the vehicle control unit 9 based on the estimated vehicle speed. Select.

  The braking force control unit 11 controls the braking force of each wheel based on a command value calculated by the vehicle control unit selected by the vehicle control selection unit 10.

  The vehicle control apparatus according to the present embodiment includes three vehicle body speeds, ie, a first estimated vehicle body speed based on a ground speed sensor value and a wheel speed, and a second estimated vehicle body speed, a vehicle control unit 8 based on the ground speed sensor value, and an estimated vehicle body speed. It has two vehicle control units called control vehicle control unit 9 based on it, and switches the vehicle body speed and the vehicle control means as shown in FIG. 1 according to the normal / abnormality of the ground speed sensor. The time chart of FIG. 2 will be described in detail with reference to FIGS.

  According to the present embodiment, when the ground speed sensor does not work normally, the control vehicle speed is switched between the second estimated vehicle speed and the first estimated vehicle speed to suppress fluctuations in the control vehicle speed. As a result, it is possible to prevent the vehicle behavior from becoming unstable due to the switching of the control vehicle body speed.

  Examples of the present invention will be described in further detail below.

  FIG. 3 is a system configuration diagram of the ABS control apparatus according to the first embodiment of the present invention.

  The vehicle 12 includes tires 13 (F is front = front wheels, R is rear = rear wheels, L is left = left, R is right = right, for example, 13FL is a left front wheel tire), and each wheel is provided. The brake caliper 21 (FR and LF are the same definition as the tire 13), an electromagnetic control valve 19 for controlling the braking force of the brake caliper, and a wheel speed sensor 20 are provided. The steering angle of the steering wheel 14 operated by the driver is detected by the steering angle sensor 31. The operation of the brake pedal 15 by the driver is boosted by the brake booster 16 and becomes the pressure of the brake master cylinder 17, and the braking force of each brake caliper 21 is controlled via the electromagnetic control valve 19 through the hydraulic piping.

  Here, the ABS control is obtained by the control unit (hereinafter referred to as C / U) 18 controlling the opening and closing of the electromagnetic control valve 19 of each wheel. C / U includes a wheel speed sensor 20 for each wheel, a steering angle sensor output 31, a longitudinal acceleration sensor 22 for detecting the longitudinal acceleration of the vehicle, a yaw rate sensor 23 for detecting the yaw rate of the vehicle, and detection values of the ground speed sensor 2. Is entered. ABS control is performed by processing the input detection value and controlling the electromagnetic control valve 19.

  FIG. 4 shows a block diagram of the C / U 18 of FIG.

  The C / U 18 includes a CPU, a ROM, a RAM, and an I / O circuit, and executes control by a program stored in the ROM. Here, the sensor value Vgss from the ground speed sensor 2 and the wheel speed Vw input from the wheel speed sensor 20 of each wheel are input, and a control signal to the electromagnetic control valve 19 of each wheel is output.

  FIG. 5 shows a control flowchart of the control unit 18 of FIG. This control flow is calculated every predetermined time T.

  In step 5-1 (hereinafter “step” is referred to as “S”), the ground speed sensor value Vgss and the wheel speed Vw are acquired from the ground speed sensor 2, the wheel speed sensor 20, and the longitudinal acceleration sensor 22, and the process proceeds to S <b> 5-2. Move.

  In S5-2, the first estimated vehicle speed V'_1 is obtained from the wheel speed Vw, and the process proceeds to S5-3.

  In S5-3, the vehicle body acceleration Gx_dV is calculated from the ground speed sensor value Vgss, and the process proceeds to S5-4. Here, the vehicle body acceleration Gx_dV is positive when the vehicle is accelerating and negative when the vehicle is decelerating.

  In S5-4, the vehicle body speed reference value V_std is calculated from the previous value Vgss_z1 of the ground speed sensor value Vgss and the vehicle body acceleration Gx_dV. At this time, the vehicle body acceleration Gx_dV may use the average value of several past values of the vehicle body acceleration Gx_dV stored in the memory, or may use the value of a sensor that detects longitudinal acceleration. When the vehicle body speed reference value V_std is calculated in S5-4, the process proceeds to S5-5.

In S5-5, the difference value ΔV from the ground speed sensor value Vgss and the vehicle body speed reference value V_std.
(= Vgss−V_std) is calculated, and the flow proceeds to S5-6.

  In S5-6, the second estimated vehicle speed V'_2 is estimated from the ground speed sensor value Vgss, the first estimated vehicle speed V'_1, the vehicle speed reference value V_std, and the difference value ΔV, and the process proceeds to S5-7.

  FIG. 6 shows an estimation method of the second estimated vehicle body speed V′_2 in S5-6 of FIG.

  First, in S6-1, the magnitude relationship between the absolute value of the difference value ΔV between the ground speed sensor value Vgss and the vehicle body speed reference value V_std and the predetermined value ΔV_thr1 is determined. If the condition that the previous value ΔV_z1 of ΔV is equal to or smaller than the predetermined value ΔV_thr1 and ΔV is greater than ΔV_thr1, the process proceeds to S6-2, and if the condition is not satisfied, the process proceeds to S6-3. When the process proceeds to S6-2, the second estimated vehicle body speed V′_2 is set to the vehicle body speed reference value V_std. On the other hand, when the process proceeds to S6-3, the coefficient k and the previous value of the second estimated vehicle speed V'_2 are set to V'_2_z1, and the second estimated vehicle speed V'_2 is estimated by the following equation (1).

V′_2 = k × V′_2_z1 + (1−k) × V′_1 (1)
However, the possible range of the coefficient k is 0 <k <1.

When estimating the second estimated vehicle body speed V′_2 by the above equation (1), the coefficient k of the equation (1) is changed by the sign of ΔV. If ΔV is positive, the process proceeds to S6-4, k = k1, and Equation (1) is calculated in S6-5. On the other hand, if ΔV is negative, the process proceeds to S6-6, and k = k2 is set, and Expression (1) is calculated in S6-6. It is desirable to set k1 to a value that is strongly influenced by the value of the first estimated vehicle body speed V′_1, and k2 is set to a value that is strongly influenced by the estimated vehicle body speed V′_2_z1. The above is the estimation method of the estimated vehicle body speed V′_2. However, the second estimated vehicle body speed V′_2 may be estimated by other methods.

  When the estimation of the estimated vehicle speed V′_2 is completed as described above, the process proceeds to S5-7 in FIG. 5 and one of the two estimated vehicle speeds of the estimated vehicle speeds V′_1 and V′_2 is selected.

  FIG. 7 shows the selection method in S5-7 of FIG.

In S7-1, a difference value ΔV ′ between the estimated vehicle speeds V′_1 and V′_2 is calculated, and the process proceeds to S7-2. If the absolute value of the difference value ΔV ′ is larger than the predetermined value ΔV′_thr1 in S7-2, the process proceeds to S7-3 and the estimated vehicle speed V ′ is set to V′_2. On the other hand, if the absolute value of ΔV ′ is smaller than the predetermined value ΔV′_thr1, the process proceeds to S7-4, and the estimated vehicle speed V ′ is set to V′_1. The above is the method for selecting the estimated vehicle speed V ′.

  When the estimated vehicle speed V ′ is selected by the above method, the process proceeds to S5-8 in FIG. In S5-8, the ground speed sensor value Vgss and the wheel speed Vw are input, and the electromagnetic control valve drive time Te1 per ABS control cycle T is calculated according to the ABS control based on the vehicle speed. Details of the ABS control based on the vehicle speed will be described later. After calculating the electromagnetic control valve drive time Te1, the process proceeds to S5-9.

  In S5-9, the estimated vehicle speed V 'and the wheel speed Vw are input, the electromagnetic control valve drive time Te2 per ABS control cycle T is calculated according to the ABS control based on the estimated vehicle speed, and the process proceeds to S5-10.

  In S5-10, the final electromagnetic control valve drive time command value Te is selected from the electromagnetic control valve drive times Te1 and Te2 calculated in S5-8 and S5-9. When the difference value ΔV between the ground speed sensor value Vgss and the vehicle body speed reference value V_std is smaller than the predetermined value ΔV_thr2, the electromagnetic control valve driving time Te1 is selected, and when the difference value ΔV is larger than the predetermined value ΔV_thr2, the electromagnetic control valve driving time Te2 is selected. Select. When the final electromagnetic control valve drive time command value is determined in S5-10, the electromagnetic control valve is driven based on this command value.

According to the present embodiment, when an abnormality occurs in the ground speed sensor during ABS braking, the vehicle speed used in the control is the ground speed sensor value Vgss → the vehicle speed reference value V_std → the second estimated vehicle speed V′_2 → The transition is made to the first estimated vehicle body speed V′_1.

  Next, control examples of the vehicle control means based on the ground speed sensor value Vgss detected by the ground speed sensor and the vehicle control means based on the estimated vehicle speed V ′ will be described.

FIG. 8 shows an example of the control of the vehicle control means based on the vehicle ground speed sensor value Vgss detected by the ground speed sensor in S5-8 of FIG.

  In FIG. 8A, the horizontal axis represents time, and the vertical axis represents speed, and shows the behavior of the wheel speed during ABS operation. In FIG. 8B, the horizontal axis represents time, and the vertical axis represents pressure, and shows the state of wheel pressure during ABS operation. Since the vehicle speed can always be detected by the ground speed sensor, the vehicle speed is estimated as in general ABS, so there is no need to finely pulsate the wheel speed. Therefore, it is not necessary to repeatedly increase and decrease the wheel pressure, the number of times of operation of the electromagnetic control valve can be greatly reduced, and the operation noise can be reduced. Further, as described above, since it is not necessary to finely pulsate the wheel speed, the wheel can be controlled at a certain slip ratio. Therefore, by obtaining an optimal slip ratio in advance, the ABS braking distance can be shortened by controlling the wheel speed using this slip ratio as the target slip ratio.

  FIG. 9 shows a control flowchart of the ABS control based on the vehicle speed V detected by the ground speed sensor in S5-8 in FIG. The control flow in FIG. 9 is calculated every predetermined time T.

  In S9-1, the target wheel speed Vw_target, which is the control target value of the wheel speed Vw, is calculated from the vehicle body speed V and the target slip ratio Slip_target1 obtained in advance. After the target wheel speed Vw_target is calculated, the process proceeds to S9-2.

In S9-2, a difference value ΔVw (= Vw−Vw_target) between the wheel speed Vw and the target wheel speed Vw_target calculated above is calculated, and the process proceeds to S9-3.

  In S9-3, the magnitude relationship between the absolute value | ΔVw | of the difference between the wheel speed Vw and the target wheel speed Vw_target and the predetermined value ΔVw_thr1 is determined. If | ΔVw | is smaller than the predetermined value ΔVw_thr1, the process proceeds to S9-4. If | ΔVw | is larger than the predetermined value ΔVw_thr1, the process proceeds to S9-5.

  When the process moves from S9-3 to S9-4, it is determined that the wheel speed Vw is controlled to the target wheel speed Vw_target, the drive time of the electromagnetic control valve is set to zero, and the process proceeds to S9-5 to hold the wheel pressure. .

  When the process moves from S9-3 to S9-6, the magnitude relationship between the wheel speed Vw and the target wheel speed Vw_target is determined in S9-6. If the wheel speed Vw is smaller than the target wheel speed Vw_target, the process proceeds to S9-7. If the wheel speed Vw is greater than the target wheel speed Vw_target, the process proceeds to S9-9.

  When the process proceeds from S9-6 to S9-7, the drive time of the electromagnetic control valve is calculated based on the difference between the target wheel speed Vw_target and the wheel speed Vw in S9-7, and the process proceeds to S9-8.

  In S9-8, the electromagnetic control valve is driven based on the calculated driving time to reduce the wheel pressure.

  On the other hand, when the process proceeds from S9-6 to S9-9, the drive time of the electromagnetic control valve is calculated based on the difference between the wheel speed Vw and the target wheel speed Vw_target in S9-9, and the process proceeds to S9-10.

  In S9-10, the electromagnetic control valve is driven based on the calculated driving time to increase the wheel pressure.

  After proceeding to any of S9-5, S9-8, and S9-10 in this way to control the wheel pressure, the process proceeds to S9-11.

In S9-11, the ABS control end determination is performed based on the ground speed sensor value V or the master pressure. When the ground speed sensor value Vgss satisfies the condition of the predetermined value V_thr1 or less or the master pressure P_master satisfies the condition of the predetermined value P_thr1 or less, the control of the ABS is terminated. On the contrary, when neither is satisfied, the process returns to S9-1 and the ABS control is continued.

  The above is the control flowchart of the ABS control based on the ground speed sensor value Vgss. However, as long as it does not depart from the gist, the ABS control based on the vehicle speed V detected by the ground speed sensor in another form is also possible without depending on the above control flow. Is possible.

  FIG. 10 shows an example of the control of the vehicle control means based on the estimated vehicle body speed V ′ in S5-9 of FIG.

  In FIG. 10A, the horizontal axis represents time and the vertical axis represents speed, and shows the behavior of the wheel during ABS operation. In FIG. 10B, the horizontal axis represents time, and the vertical axis represents pressure, and shows the state of wheel pressure during ABS operation. In the ABS control based on the estimated vehicle speed, the vehicle speed is estimated based on the wheel speed. Therefore, the estimation of the vehicle body speed and the securing of the braking force are frequently repeated. Specifically, by reducing the wheel pressure, the wheel speed is returned to near the actual vehicle speed (= slip ratio is reduced), and the vehicle speed is estimated. Since the braking force is generated after the vehicle body speed is estimated, the wheel pressure is increased and the wheel speed is decreased (= slip ratio is increased).

  FIG. 11 shows a control flowchart of the ABS control based on the estimated vehicle speed in S5-9 in FIG. The control flow in FIG. 11 is calculated every predetermined time T.

  In S11-1, the estimated vehicle body speed V'_1 is estimated from the information on the wheel speed Vw. As an estimation method, it is common to use a select high method in which the fastest wheel speed value among the four wheels is regarded as the vehicle body speed. When the estimated vehicle speed V′_1 is estimated in S11-1, the process proceeds to S11-2.

In S11-2, the estimated vehicle body speed V′_1 and a preset target slip ratio Slip_
From the target 2, a pressure increase side target wheel speed Vw_target 1 that is a target value of the wheel speed when the wheel pressure is increased and a pressure reduction side target wheel speed Vw_target 2 that is a target value of the wheel speed when the wheel pressure is decreased are calculated. When the calculation of the target wheel speed Vw_target1, Vw_target2 is completed, the process proceeds to S11-3.

  In S11-3, the magnitude relation between the wheel speed Vw and the pressure increase side target wheel speed Vw_target1 is determined. If the wheel speed Vw is higher than the pressure increase side target wheel speed Vw_target1, the process proceeds to S11-4, and if it is smaller, the process proceeds to S11-5.

  When the process moves from S11-3 to S11-4, the previous value Vw_target_z1 of the target wheel speed is referred to. When the previous value is the pressure increase side target wheel speed Vw_target1_z1, the process proceeds to S11-6, and the target wheel speed Vw_target is switched to the pressure reduction side target wheel speed Vw_target2. If the previous value is not the pressure increase side target wheel speed Vw_target1, the process proceeds to S11-7, and the target wheel speed Vw_target is not switched.

On the other hand, when the process moves from S11-3 to S11-5, the magnitude relationship between the wheel speed Vw and the reduced pressure side target wheel speed Vw_target2 is determined. Wheel speed Vw is reduced pressure target wheel speed Vw_
If it is smaller than target2, the process proceeds to S11-8, and if it is greater, the process proceeds to S11-7.

When the process moves from S11-5 to S11-8, the previous value Vw_target_z1 of the target wheel speed is referred to. When the previous value is the decompression side target wheel speed Vw_target2_z1, the process proceeds to S11-9, and the target wheel speed Vw_target is switched to the pressure increase side target wheel speed Vw_target1. When the previous value is not the decompression side target wheel speed Vw_target2_z1,
Moving to S11-7, the target wheel speed Vw_target is not switched.

  On the other hand, when the process moves from S11-5 to S11-7, the target wheel speed Vw_target is not switched.

  When the target wheel speed Vw_target is set in the above steps, the process proceeds to S11-10, and the difference value ΔV2 between the wheel speed Vw and the target wheel speed Vw_target is calculated. When the difference value ΔV2 is calculated, the process proceeds to S11-11, and the drive time Te of the electromagnetic control valve per ABS control cycle T is calculated based on ΔV2. When the drive time Te is calculated, the process proceeds to S11-12, and the electromagnetic control valve is driven. After driving the electromagnetic control valve, the process proceeds to S11-13.

  In S11-13, the ABS control end determination is performed based on the estimated vehicle speed V 'or the master pressure. When the estimated vehicle speed V ′ satisfies either the predetermined value V_thr2 or less, or the master pressure P_master satisfies the predetermined value P_thr1 or less, the ABS control is terminated. On the contrary, when neither is satisfied, the process returns to S11-1 to continue the ABS control.

  The above is a control flowchart of the ABS control based on the estimated vehicle speed V ′, but ABS control based on the estimated vehicle speed V ′ in other forms is also possible without departing from the gist, without departing from the gist.

12 and 13 show examples of time charts for control according to the present embodiment. In each figure, (a) shows the time on the horizontal axis and the speed on the vertical axis, and (b) shows the time on the horizontal axis and the pressure on the vertical axis.

  In FIG. 12, the ground speed sensor is initially normal and ABS control is performed based on the ground speed sensor value Vgss. However, an abnormality occurs that the ground speed sensor measures higher than the actual vehicle speed on the way. The behavior of the wheel speed and the wheel pressure when switching to the ABS control based on V ′ is shown. There is a slight time lag between the actual occurrence of ground speed sensor abnormality and the detection of ground speed sensor abnormality by the system. Therefore, the vehicle speed reference value V_std calculated based on the ground speed sensor value Vgss is slightly higher than the actual vehicle speed in the case shown in FIG. For this reason, the initial value of the estimated vehicle speed V′2 is also slightly higher than the actual vehicle speed. Therefore, when the system detects an abnormality in the ground speed sensor, the wheel pressure is gradually decreased, and the wheel speed is controlled to gradually approach the actual vehicle speed. As a result, it is possible to suppress an increase in the estimated vehicle body speed V′_2 and to suppress a decrease in braking force due to a significant decrease in the slip ratio.

In FIG. 13, the ground speed sensor is initially normal and ABS control based on the vehicle speed V is performed. However, an abnormality occurs that the ground speed sensor measures lower than the actual vehicle speed on the way, and the estimated vehicle speed V ′ The behavior of the wheel speed and the wheel pressure in the scene switched to the ABS control based on is shown. In this case, the vehicle body speed reference value V_std calculated based on the vehicle body speed V is slightly lower than the actual vehicle body speed. For this reason, the initial value of the estimated vehicle speed V′2 is also slightly lower than the actual vehicle speed. Therefore, when the system detects an abnormality in the ground speed sensor, the wheel pressure is sharply decreased, and control is performed so that the wheel speed is quickly brought close to the actual vehicle speed. As a result, unnecessary lowering of the estimated vehicle body speed V′_2 can be suppressed, and wheel locking due to an increase in the slip ratio can be suppressed.

  FIG. 14 shows a vehicle speed measurement method by the ground speed sensor 2 of FIG. 3, and FIG. 15 shows an installation diagram of the ground vehicle speed sensor 2 of FIG.

FIG. 14 is a top view of the vehicle. Two ground speed sensors 2 are installed at the front center of the vehicle. FIG. 15 is a view of the vehicle as viewed from the side. The radio wave irradiation surface is directed in the direction of the angle θ with respect to the horizontal plane so that the radio wave is applied to the ground at an incident angle θ. In FIG. 14, the longitudinal direction of the vehicle is taken as the x-axis, and the left-right direction (lateral direction) is taken as the y-axis. The ground speed sensor a is directed to the angle a with respect to the x axis, and the ground speed sensor b is directed to the angle b. However, if the clockwise direction from the x-axis is taken as a positive angle, the angle a is a <0. Let L be the distance from the vehicle center of gravity to the ground speed sensor installation point. At this time, it is assumed that the vehicle generates a side skid angle β and a yaw rate γ, travels at a speed Vc, and the two ground speed sensors measure the speeds V _a and V _b . Then, the relationship of the following two formulas is established.

  From equations (2) and (3)

As a result, the vehicle longitudinal velocity V _x and the lateral velocity V _y are as follows.

Thus, for example, when the ABS is operated in a vehicle traveling straight, V _x when β = 0 and γ = 0 is the ground speed sensor value Vgss in the present embodiment.

  FIG. 16 shows a control flowchart according to the second embodiment of the present invention.

This is another embodiment of the flowchart of FIG. 7 of the first embodiment, and other configurations are the same as those of the first embodiment. In S16-1, a difference value ΔV ′ between the estimated vehicle speeds V′_1 and V′_2 is calculated, and the process proceeds to S16-2. In S16-2, the wheel speed dVw is calculated for the fastest wheel speed among the four wheels, and the process proceeds to S16-3. In S16-3, the absolute value of ΔV ′ is a predetermined value ΔV′_.
If the condition that the wheel speed dVw is smaller than thr1 and the wheel speed dVw is smaller than the predetermined value ΔVw_thr1, the process proceeds to S16-5, and the estimated vehicle speed V ′ is set to V′_1. On the other hand, when the condition of S16-3 is not satisfied, the process proceeds to S16-4, and the estimated vehicle speed V ′ is set to V′_2.

  In Example 1, at the moment when it is determined that the ground speed sensor is abnormal, the second estimated vehicle body speed V′_2 is used as the vehicle body speed reference value V_std, and the initial value of the second estimated vehicle body speed V′_2 in Expression (1) is used. However, the ground speed sensor output value Vgss may be calculated as an initial value.

  Further, in the equation (2), the calculation is performed using the past value V′_2_z1 of the second estimated vehicle body speed, but the initial value V′_2_init of the second estimated vehicle body speed is used as in the following equation (4). May be.

V′_2 = k × V′_2_init + (1−k) × V′_1 (4)
Other configurations are the same as those of the first embodiment.

  As the initial value of the second estimated vehicle body speed in the expressions (1) and (4), the ground speed sensor value immediately before the ground speed sensor is determined to be abnormal may be used. Other configurations are the same as those of the first embodiment.

  When estimating the second estimated vehicle body speed using Equation (1) or Equation (4), the coefficient k may be changed according to the estimated road surface friction coefficient. Other configurations are the same as those of the first embodiment.

  Although the second estimated vehicle speed is estimated by the equation (1), the vehicle speed reference value may be the second estimated vehicle speed. Other configurations are the same as those of the first embodiment.

In the first embodiment, a ground speed sensor is used as a means for measuring the vehicle speed for control.
The vehicle body speed V for control may be measured from the moving distance of the vehicle every predetermined time using GPS (Global Positioning System). Other configurations are the same as those of the first embodiment.

  FIG. 17 shows an installation diagram of the ground speed sensor 2 according to the eighth embodiment of the present invention.

  In the first embodiment, the two ground speed sensors are installed so as to be adjacent to the center of the front of the vehicle as shown in FIG. 14. However, even if the two ground speed sensors are separated as shown in FIG. good. FIG. 17 is a view of the vehicle as viewed from above. In this case, the two ground speed sensors are installed so that the angles from the x-axis are a and b, and the directions of the two ground speed sensors intersect on the vehicle center of gravity. With this setting, it becomes unnecessary to consider the yaw rate component of the lateral velocity, and by solving the simultaneous equations of the following equations (5) and (6),

The longitudinal speed V _x and the lateral speed V _y can be obtained as follows.

  Other configurations are the same as those of the first embodiment.

  FIG. 18 is a schematic configuration diagram of the ground speed sensor 2 according to the ninth embodiment of the present invention.

  In the first embodiment, the difference between the ground speed sensor value and the vehicle body speed reference value and the time differential value of the ground speed sensor value are used as the abnormality determination of the ground speed sensor. A power supply voltage can also be used. As shown in FIG. 18, a power supply voltage monitoring unit for monitoring the power supply voltage is added to the ground speed sensor composed of a radio wave transmission / reception unit that transmits and receives radio waves, a signal processing unit, and a signal output unit, and the power supply board supplies the ground speed sensor Measure the voltage to be applied. And when a measurement voltage leaves | separates from a predetermined range from a rated voltage, a ground speed sensor judges that it is abnormal. Other configurations are the same as those of the first embodiment.

The functional block diagram of the control apparatus of the vehicle which makes one Embodiment of this invention is shown. The time chart by control by the control apparatus of FIG. 1 is shown. 1 shows a system configuration diagram of an ABS control apparatus according to Embodiment 1 of the present invention. The block block diagram of C / U18 of FIG. 3 is shown. The control flowchart of the control unit 18 of FIG. 3 is shown. A method for estimating the second estimated vehicle body speed V′_2 in S5-6 in FIG. 5 will be described. The selection method in S5-7 of FIG. 5 is shown. An example of the control of the vehicle control means based on the vehicle ground speed sensor value Vgss detected by the ground speed sensor in S5-8 in FIG. FIG. 6 shows a control flowchart of ABS control based on the vehicle speed V detected by the ground speed sensor in S5-8 of FIG. An example of the control of the vehicle control means based on the estimated vehicle body speed V ′ in S5-9 in FIG. 5 will be shown. FIG. 6 shows a control flowchart of ABS control based on an estimated vehicle speed in S5-9 of FIG. The example of the time chart of the control by this embodiment is shown. The example of the time chart of the control by this embodiment is shown. The vehicle speed measurement method by the ground speed sensor 2 of FIG. 3 is shown. The installation figure of the ground speed sensor 2 of FIG. 3 is shown. The control flowchart which makes Example 2 of the present invention is shown. The installation figure of the ground speed sensor 2 which makes Example 8 of this invention is shown. The structure schematic of the ground speed sensor 2 which comprises Example 9 of this invention is shown.

Explanation of symbols

2 Ground speed sensor 12 Vehicle 13 Tire 14 Steering 15 Brake pedal 16 Brake booster 17 Brake master cylinder 18 Control unit (C / U)
19 Electromagnetic control valve 20 Wheel speed sensor 21 Brake caliper 22 Longitudinal acceleration sensor 23 Yaw rate sensor

Claims (13)

A first vehicle body speed estimating unit for determining a first estimated vehicle body speed based on a wheel speed obtained from an output signal of the wheel speed sensor;
A ground speed sensor abnormality detecting unit for detecting an abnormal state of the ground speed sensor;
A second vehicle speed estimation unit for obtaining a second estimated vehicle speed based on a vehicle speed obtained from an output signal of the ground speed sensor, the first estimated vehicle speed, and an abnormal state of the ground speed sensor;
An estimated vehicle speed selector that selects an estimated vehicle speed to be used in vehicle control from among the first estimated vehicle speed, the second estimated vehicle speed, and the wheel speed;
Based on the estimated vehicle speed selected by the estimated vehicle speed selection unit and a first vehicle control unit that controls the vehicle based on the vehicle speed and the wheel speed based on an abnormal state of the ground speed sensor. A vehicle control selection unit for selecting one of the second vehicle control units for controlling the vehicle;
A braking force control unit that outputs a signal for controlling the braking force of each wheel based on a control command value calculated by the vehicle control unit selected by the vehicle control selection unit;
A control device for a vehicle. The vehicle control device according to claim 1,
The ground speed sensor abnormality detection unit detects a vehicle speed reference value calculation unit that calculates a vehicle speed reference value based on the vehicle speed, and detects an abnormal state of the ground speed sensor based on the vehicle speed and the vehicle speed reference value. A vehicle control device. The vehicle control device according to claim 2,
The ground speed sensor abnormality detection unit calculates a difference value between the vehicle speed detected by the ground speed sensor and a vehicle speed reference value calculated by the vehicle speed reference value calculation unit, and the difference value is a predetermined value. A vehicle control device that detects a vehicle speed error measurement abnormality of the ground speed sensor when the range is exceeded. The vehicle control device according to claim 1,
The ground speed sensor abnormality detection unit calculates a time change rate of the vehicle body speed detected by the ground speed sensor, and detects an abnormality of the ground speed sensor when the time change rate exceeds a predetermined range. A vehicle control device. The vehicle control device according to claim 2,
The second vehicle speed estimation unit detects the vehicle speed measurement error occurrence abnormality in the ground speed sensor abnormality detection unit, and uses the vehicle speed reference value calculated by the vehicle speed reference value calculation unit as the vehicle speed. Vehicle control device to be estimated. The vehicle control device according to claim 1,
The second vehicle speed estimation unit has a function of estimating a vehicle speed when an error occurrence abnormality measured higher than an actual vehicle speed is detected by the ground speed sensor abnormality detection unit, and a ground speed sensor abnormality detection unit A vehicle control device having a function of estimating a vehicle body speed when an abnormality of an error occurrence that is measured lower than an actual vehicle body speed is detected. The vehicle control device according to claim 1,
The vehicle body speed selection unit is a vehicle control device that always selects an estimated vehicle body speed estimated by the second vehicle body speed estimation unit until a predetermined condition is satisfied. The vehicle control device according to claim 1,
The vehicle speed selector selects a difference value between the estimated vehicle speed based on the wheel speed estimated by the first vehicle speed estimator and the estimated vehicle speed estimated by the second vehicle speed estimator within a predetermined value. A vehicle control device that selects an estimated vehicle body speed based on a wheel speed estimated by the first vehicle body speed estimating unit. The vehicle control device according to claim 1,
The vehicle speed selector selects a difference value between the estimated vehicle speed based on the wheel speed estimated by the first vehicle speed estimator and the estimated vehicle speed estimated by the second vehicle speed estimator within a predetermined value. And the wheel estimated by the first vehicle body speed estimating unit when the temporal change rate of the highest wheel speed among the wheel speeds detected by the wheel speed detecting unit falls within a predetermined value. A vehicle control device that selects an estimated vehicle body speed based on a vehicle speed. The vehicle control device according to claim 1,
The second vehicle control unit is a vehicle control device that decreases a control command value of the braking force control unit when an abnormality is detected by the ground speed sensor abnormality detection unit. The vehicle control device according to claim 1,
When the estimated vehicle speed estimated by the second vehicle speed estimation unit is selected by the estimated vehicle speed selection unit, the second vehicle control unit sets the control target value of the wheel speed to the second vehicle speed. A control device for a vehicle that makes an estimated vehicle body speed estimated by an estimation unit. The vehicle control device according to claim 1,
The ground speed sensor abnormality detection unit inputs power supply voltage information measured by the ground speed sensor, and determines that the ground speed sensor is abnormal when the input power supply voltage is out of a predetermined range. Control device. The first estimated vehicle body speed is obtained based on the wheel speed obtained from the output signal of the wheel speed sensor,
Determining a second estimated vehicle speed based on the vehicle speed determined from the output signal of the ground speed sensor, the first estimated vehicle speed, and an abnormal state of the ground speed sensor;
Selecting an estimated vehicle speed to be used in vehicle control from among the first estimated vehicle speed, the second estimated vehicle speed, and the wheel speed;
A first vehicle control that controls the vehicle based on the vehicle body speed and the wheel speed based on an abnormal state of the ground speed sensor, and a second vehicle that controls the vehicle based on the selected estimated vehicle body speed. Select one of the controls,
A vehicle control method for controlling a braking force of each wheel based on a control command value calculated by the selected vehicle control.

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