JPH0688524B2 - Vehicle deceleration control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for controlling braking of a vehicle, and more particularly to a vehicle deceleration control device for suitably controlling the degree of deceleration.

[Prior Art] When braking a vehicle, the coefficient of friction between the wheel and the road surface μ
Plays an important role. That is, as long as the maximum frictional force is not exceeded, if the vehicle load is small, a large braking force can be obtained even if the brake depression is small, but if the vehicle load is large, the same braking force as when the load is small is obtained. In this case, it is necessary to increase the brake pressure by increasing the brake depression. Therefore, depending on the vehicle load,
The feeling of depression of the brake is different, and the driver may feel a sense of discomfort in the braking operation and may perform an inappropriate braking operation.

Also, the maximum frictional force is the friction coefficient μ due to the road surface condition and the tire.
Therefore, even if the driver steps on the brake to obtain a large deceleration, the excessive braking force only causes the tire to lock. Therefore, an anti-skid system has been proposed which compensates for this excessive braking force and controls so that the slip ratio becomes 20%, for example. According to this device, when the driver requests the deceleration to the extent that the anti-skid control needs to work, the control is performed so as to give the maximum braking force determined by the maximum friction coefficient μ of the road surface.

[Problems to be Solved by the Invention] The above anti-skid control gives the maximum braking force,
The braking force in the middle of the range, especially the feeling of strangeness of the driver's braking operation itself, has not been resolved.

In addition, the brake depression and the brake pressure output system are provided separately to control the brake pressure appropriately (Japanese Patent Laid-Open No. 59-
No. 160653) also exists, but again, the driver's operational discomfort is not taken into consideration.

Furthermore, since the anti-skid control is a control for maintaining the steerability when a large braking force is applied during high speed running,
It has been desired to make the control response as high as possible.

The present invention has been completed for the purpose of improving the uniformity of braking operation and the response of control.

[Means for Solving Problems] In order to solve the above problems, the present invention, as illustrated in FIG. 1, includes a brake operation amount detecting means M1 for detecting a brake operation amount of a vehicle driver, and a vehicle. Acceleration detecting means M2 for detecting the acceleration of the vehicle, brake pressure adjusting means M3 for adjusting the brake pressure for braking the wheels, vehicle speed detecting means M4 for detecting the vehicle speed, and rotational speed detecting means for detecting the rotational speed of the wheels. A slip ratio is calculated from M5, a brake switch M6 that detects the presence / absence of a brake operation by the vehicle driver, the vehicle speed detected by the vehicle speed detection means M4, and the wheel rotation speed detected by the rotation speed detection means M5. Slip ratio calculating means M7 for controlling the brake pressure adjusting means M3 according to the comparison result of the slip ratio calculated by the slip calculating means M7 and the predetermined slip ratio. A step M8, the control means M8 controls the brake pressure adjusting means M3 to reduce the brake pressure when the slip ratio calculated by the slip ratio calculating means M7 exceeds a predetermined slip ratio, When the slip ratio calculated by the slip ratio calculating means M7 does not exceed the predetermined slip ratio, when the brake switch M6 detects that there is a brake operation, the target for the brake operation amount detected by the brake operation amount detecting means M1. The acceleration is calculated based on a predetermined pattern, and the brake pressure adjusting means M3 is set so that the acceleration detected by the acceleration detecting means M2 becomes the target acceleration.
The vehicle deceleration control device is characterized by controlling the brake pressure adjusting means M3 so that the brake pressure is reduced when the brake switch M6 detects that there is no brake operation.

Here, the brake operation amount detection means M1 is, for example, for detecting the depression amount of the brake pedal, and is for detecting the pedal position with a potentiometer, a differential transformer, or the like.

The acceleration detecting means M2 detects the acceleration applied to the vehicle and is a so-called G sensor. Since it is braking control, the acceleration has a negative value.

The brake pressure adjusting means M3 is for adjusting the pressure of the brake pressure transmission system so as to pressurize, depressurize or hold it, and has, for example, a predetermined volume effective for the brake pressure transmission system. It has a structure that expands to reduce the force transmitted to the braking member and performs the opposite control at the time of pressurization, and has a pump that serves as a pressure source, a reservoir, and a switching valve to increase or decrease the pressure in the direct brake pressure transmission system. Various configurations such as holding control can be considered.

Further, the vehicle speed detection means M4 is based on a ground speed sensor utilizing the Doppler effect or the like, or the speed obtained from the idle wheel rotational speed immediately before the start of braking, and the acceleration detection means M2
Acceleration of the vehicle determined by (deceleration during braking)
Can be detected by any method, such as by sequentially integrating.

The rotation speed detection means M5 is for detecting the rotation speed of the wheels. The rotation speed of the wheel may be obtained by a rotation speed sensor provided on the wheel, or may be obtained by various methods such as obtaining by integrating the wheel rotation torque in consideration of the inertia of the wheel. .

The slip ratio calculating means M7 and the control means M8 can be configured as a discrete electronic circuit, or can be configured as a logical operation circuit using a microcomputer or the like.

The above-mentioned predetermined slip ratio of the slip ratio is usually set to a value that maximizes the braking force, but it can be changed according to the operation of the vehicle. For example, there is a case where the slip ratio to be realized is changed according to the depression state of the brake pedal. FIG. 2 shows the relationship between the slip ratio SL and the frictional force M. As shown in the figure, the frictional force M becomes maximum when the slip ratio SL is around 20%, so that the wheel exerts the maximum braking force. .

The control means M8 uses not only the control circuit used for the conventional anti-skid control but also the braking member of the wheel based on the optimum feedback gain F previously determined according to the dynamic model of the system relating to the braking of the vehicle. It can be configured such that the brake pressure to be transmitted is known, the feedback control amount of the brake pressure adjusting means M3 for adjusting to this brake pressure is obtained, and a control signal corresponding to this is output. That is, the control means M8 can also be configured as an additional integral type optimum regulator that determines the optimum feed bag amount from the detected state variable amount and the predetermined slip ratio.

The method of constructing the optimum integral regulator is described in detail in, for example, Katsuhisa Furuta [Linear System Control Theory] (Showa 51) Shoshodo.

[Operation and Effect of the Invention] A vehicle deceleration control device according to the present invention, which relates to slip ratio calculation means
M7 calculates the slip ratio from the vehicle speed detected by the vehicle speed detection means M4 and the wheel rotation speed detected by the rotation speed detection means M5.

When the slip ratio does not exceed the predetermined slip ratio and the brake switch M6 detects that there is a brake operation, the control means M8 sets a predetermined target acceleration for the brake operation amount detected by the brake operation amount detection means M1. The brake pressure adjusting means M3 is controlled so that the acceleration detected based on the pattern and detected by the acceleration detecting means M2 becomes the target acceleration. As a result, the acceleration with respect to the brake operation amount is always the same regardless of the load of the vehicle and the road surface condition, so that the same braking pattern can be obtained constantly, and the driver's operation is stable. can get.

When the slip ratio does not exceed the predetermined slip ratio and it is detected by the brake switch M6 that there is no brake operation, the brake pressure adjusting means M3 is controlled to immediately reduce the brake pressure and loosen the brake. As a result, for example, when the driver releases the brake operation immediately before the slip ratio exceeds a predetermined value, the brake is immediately relaxed to prevent the slip ratio from increasing, and it is possible to perform control without feedback delay in the feedback system. can get.

Furthermore, if the slip ratio exceeds the predetermined slip ratio,
Immediately, the brake pressure adjusting means M3 is controlled so as to reduce the brake pressure and loosen the brake. As a result, it is possible to obtain an effect that the feedback system can be controlled without a response delay.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. It is needless to say that the present invention is not limited to the following examples and can be implemented in other modes without departing from the gist of the present invention.

FIG. 3 is a schematic configuration diagram showing an overall configuration of a vehicle deceleration control device mounted on a four-wheel vehicle as one embodiment of the present invention, and FIG. 4 is a control system for the right front wheel together with a block diagram of an electronic control unit. It is a control system diagram shown. First, the overall configuration and the outline of the hydraulic system / electrical system will be described.

As shown in the figure, hydraulic braking devices 11, 12, 13 and 14 are provided on the wheels 1, 2, 3 and 4 of the vehicle, and the left and right front wheels 1 and 2 are electromagnetic sensors that detect their rotational angular velocity. Pickup type rotation angular velocity sensors 15 and 16 are attached. Further, the rotational angular velocity of the rear wheels 3 and 4 which receives the rotation of the main shaft 19 of the transmission 18 via the differential gear 21 and rotates, is detected by a rotational angular velocity sensor 22 provided in the transmission 18.

The hydraulic brake devices 11 to 14 provided on each wheel brake the rotation of each wheel 1 to 4 by using the high hydraulic pressure generated by the hydraulic pressure generating device 43 as a brake hydraulic pressure, and the brake hydraulic pressure is applied to the actuators 31, 32, 33. Adjusted by
The actuators 31, 32, and 33 independently control the brake hydraulic pressures of the right front wheel 1, the left front wheel 2, the left and right rear wheels 3 and 4, and are controlled by an electronic control unit (ECU) 40. The structure of the actuators 31 to 33 will be described in detail later, but the actuators 31 to 33 function as brake pressure adjusting means M3 for adjusting the brake pressure of the wheels 1 to 4.

The hydraulic system RHS of the brake hydraulic pressure to the right front wheel 1 is detected by the hydraulic pressure sensor 51, the hydraulic pressure of the hydraulic system LHS of the left front wheel 2 is measured by the hydraulic pressure sensor 52, and the hydraulic pressure of the hydraulic system BHS of the rear wheels 3, 4 is measured by the hydraulic pressure sensor 53. , Respectively detected.

The ECU 40 detects not only signals in accordance with the oil pressures from these oil pressure sensors 51, 52, 53, but also rotation angular velocity signals from the rotation angular velocity sensors 15, 16, 22 as well as vehicle acceleration (including deceleration). A signal from the acceleration sensor 54, a signal from the brake sensor 25 that detects the operation amount of the brake pedal 24, a signal from the brake switch 26, and the like are input, and the actuators 31, 32, and 33 are controlled, respectively, and each of the wheels 1 to 4 is controlled. The rotation angular velocity ω is controlled.

Since the control of the braking force of the right front wheel 1, the left front wheel 2, and the rear wheels 3 and 4 is independently performed, the control of the right front wheel 1 will be described below. FIG. 4 is a block diagram mainly showing the system for controlling the braking of the right front wheel 1. ECU4 as shown
0 is provided with a power supply unit 58 which receives a power supply voltage from a battery 57 via an ignition key 56 and supplies a constant voltage to the entire unit, and a well-known CPU 61, ROM 63, RAM 65 and the like, an output port 67, The analog input port 69, the pulse input port 71, the level input port 72 and the like are connected to each other by a bus 73 and are configured as a logical operation circuit. When a predetermined condition is satisfied, the ECU 40 drives the spring offset type 3 port 3 position valve 75 in the actuator 31 to control the brake hydraulic pressure transmitted from the hydraulic pressure generating device 43 to the hydraulic brake device 11, which is a braking member. . When the brake hydraulic pressure rises, the hydraulic brake device 11 works to press the friction pad 83 against the disk 82 rotating with the wheel 1 to stop the rotation of the wheel 1. That is, the ECU 40 corresponds to the slip ratio calculation means M7 and the control means M8.

Hydraulic pressure is transmitted from the hydraulic pressure generation device 43 to the actuator 31. The hydraulic pressure is guided to the hydraulic brake device 11 via the 3-port 3-position valve 75. The other actuators 32 and 33 have the same configuration. The pressure oil is pumped through the check valve 43a,
The discharge is made to the reservoir 43b.

The spring-offset 3-port 3-position valve 75 has a position a shown in FIG.
Position), and when the lower solenoid is energized, it is in the lower switching position b (hereinafter referred to as the second position) in FIG. 4, and when the upper solenoid is energized, it is the upper switching position in FIG. It is configured to be in position c (hereinafter referred to as the third position).

Since the actuator 31 is configured as described above,
The hydraulic pressure is maintained at the position a of the valve 75, the hydraulic pressure increases at the position b, and the hydraulic pressure decreases at the position c.

Next, FIG. 5 shows the processing executed by the ECU 40 in the above-described configuration.

First, when the process is started, the vehicle speed V is detected in step 202 after the initialization in step 200. The vehicle speed is the average value of the detection values of the rotational angular velocity sensors 15 and 16 provided for the wheels 1 and 2 immediately before the start of braking, and the acceleration sensor 5 thereafter.
Calculated as the sum of 4 and the single integration of the detected acceleration.

Next, at step 204, the rotational angular velocity ω of the wheel 1 is detected by the output value of the rotational angular velocity sensor 15. Then step
At 206, the slip ratio SL is calculated by the following formula.

SL = (V−ωr) / V where r represents the radius of the wheel 1.

Next, at step 208, the slip ratio SL is compared with a predetermined slip ratio SO for the judgment. SO is normally set to a value of 0.2 (20%) that produces maximum braking force. If the slip ratio SL is equal to or less than the predetermined value SO, the wheel 1
Assuming that the lock has not occurred, the processing from step 210 onward is performed. First, in step 210, the brake switch 26
Is checked to see if it is on. If on, step
At 220, the brake sensor 25 reads the depression amount Bf of the brake pedal. Subsequently, at step 230, the target acceleration βt is obtained from the above-mentioned amount of depression Bf by an arithmetic expression or table. For example, the depression amount Bf and the target acceleration βt are expressed in the relationship shown in FIG. However,
Since the acceleration is due to braking, βt has a negative value. Next, at step 240, the actual vehicle acceleration β is read from the acceleration sensor 54. Next, at step 250, the target acceleration βt and the actual acceleration β are compared.

Here, if βt is larger, it is 3 in step 260.
A signal is output to the port 3 position valve 75 to set the valve position to position b. As a result, the pressure from the hydraulic pressure generator 43 is applied, the hydraulic pressure applied to the hydraulic brake device 11 rises, and the braking force increases.

When βt is equal to β, the valve position becomes the position a in step 270, the hydraulic pressure of the hydraulic brake device 11 becomes constant, and the braking force also does not change.

If βt is smaller than β, the valve position is changed to the position c in step 280, the pressure oil is reduced from the hydraulic brake device 11, and the braking force is reduced.

Thus, when the valve position operation is completed, the step
The process starts from 202.

If SL exceeds SO in step 208, step 2
08 is executed and the brake pressure drops.

Timing charts of the amount of depression of the brake pedal, the deceleration (negative acceleration) and the vehicle speed when the processing of the above-described embodiment is performed are shown in FIGS. 7 (a), 7 (b) and 7 (c).

Before time t0, the vehicle travels at vehicle speed Vs, and from time t0 to time t2
It is assumed that the driver depresses the brake pedal in the pattern as shown in (a). In this embodiment, since the depression amount and the acceleration have a constant correspondence on any road, the deceleration increases in a pattern as shown in FIG. In the case of asphalt road surface (solid line), deceleration increases until time t2. Therefore, the vehicle speed drastically decreases along the quadratic curve from time t0 to time t2.
After that, it decreases linearly until the vehicle completely stops (time t3). The vehicle speed calculated from the rotational angular speed of the wheel 1 is shown by a dotted line.

On the other hand, in the case of a road surface with a smaller friction coefficient such as a frozen road surface (dashed line), from time t0 to t1, it drops sharply like asphalt, but after that, as shown by the chain double-dashed line, The vehicle speed calculated from the rotational angular velocity is 80, which is the actual vehicle speed.
%, Step 208 is executed, and the deceleration becomes constant (dashed-dotted line) despite the increase in the depression amount of the brake pedal. Therefore, from time t1 to t4, the vehicle speed decreases with a gentler straight line than asphalt.

Since the present embodiment is configured as described above, when the slip ratio SL does not exceed the predetermined slip ratio SO and the brake switch 26 is on, the acceleration with respect to the brake operation amount is the load of the vehicle or the road surface condition. Since the same degree of braking is always obtained regardless of the situation, the same braking pattern can be obtained constantly, and the driver's operation is stabilized.

Further, when the slip ratio SL does not exceed the predetermined slip ratio SO and when the brake switch 26 is off, the brake pressure is immediately reduced to loosen the brake. For example, immediately before the slip ratio SL exceeds the predetermined slip ratio SO. Moreover, when the driver releases the brake operation, the brake is immediately relaxed to prevent the slip ratio SL from increasing, and the feedback system can be controlled without a response delay.

Further, when the slip ratio SL exceeds the predetermined slip ratio SO, the brake pressure is immediately reduced to loosen the brake, so that there is an effect that control without response delay of the feedback system becomes possible.

Unlike the braking control adopted in the ECU 40 of the above-described embodiment, the brake pressure to be transmitted to the hydraulic brake device 11 is known based on the optimum feedback gain F that is determined in advance according to the dynamic model of the system relating to vehicle braking. The ECU 40 may be configured to obtain a feedback control amount to be adjusted to this brake pressure and output a control signal corresponding to this. That is, the ECU 40 is configured as an additional integral type optimal regulator that determines the optimal feedback amount from the detected state variable amount and slip ratio.

This additional integral type optimal regulator configuration method is described in detail in, for example, Katsuhisa Furuta "Linear System Control Theory" (Showa 51) Shoshodou, etc. We will give a perspective.

In the following explanation, Etc. show the vector quantity (matrix), The subscript ^{T such as} is the transpose of the matrix, Subscript ^{-1 such as} That it is an estimate, Is a quantity that is handled by another system, which is generated by transformation etc. from the system to be controlled, here, a state observer (hereinafter called observer), and a symbol such as y · is a target value This is shown respectively.

In the braking control of the controlled object, here the vehicle, the dynamic behavior of this controlled object is Is a state variable quantity that represents the internal state of the system related to vehicle braking, Control input quantities for the controlled object, that is, the hydraulic pressure u, Let be the control output quantities of the controlled object, here the rotational angular velocity ω, the variable DLY corresponding to the response delay of the control system, the actual hydraulic pressure P, etc. It is described as. Equations (a1) and (a2) are written in a discrete system, and the subscript k indicates that it is the current value, k + 1
Indicates that the value is at the next sampling time.

Indicates the internal state of the vehicle braking system Shows information about the history of the system that is necessary and sufficient for predicting the future influence of the control system. Therefore, a dynamic model of the system for braking the wheel 1 is clarified, and the equation (a1) (a2) If you can determine Thus, the braking of the vehicle can be optimally controlled by using.
In actual control, it is necessary to expand the system, which will be described later.

By the way, a dynamic model of a complex controlled object such as vehicle braking control may not be a linear model in the entire control range. However, when the vehicle is brake-controlled under a predetermined condition, for example, at a certain vehicle speed, it can be considered that a linear approximation is established in the vicinity of that state. Can be built. Therefore, when the dynamic model is non-linear like the system related to vehicle braking, linear approximation can be performed by separating into a plurality of stationary conditions, and each dynamic model can be calculated. It can be set.

Here, the dynamic model of the system relating to braking can be constructed from the law of motion or the like by prescribing a mechanical model of the brake hydraulic system, or can be determined by performing system identification. For the response delay of the control system, an approximate model can be constructed by the transient response method.

Once you have a dynamic model, And the rotational angular velocity ω (k) of the wheel 1 and its target rotational angular velocity ω
Of the actuator 31 for controlling the brake pressure of the wheel 1 whose feedback amount is determined from (k) Is theoretically optimally determined. Normally, in a vehicle braking control system, various quantities that are directly involved in vehicle braking include, for example, the load applied to the wheel 1, the acceleration, the moving speed of oil or gas transmitted to the hydraulic brake device 11, and the dynamics of the hydraulic brake device 11. Behavior, and response delay of hydraulic system RHS However, it is extremely difficult to directly observe most of these quantities. Therefore, in such a case, a means called a state observer is configured in the ECU 40 to You can estimate what you need. This is the so-called observer in modern control theory, and various observers and their design methods are known. These are, for example, "Mechanical system control" by Katsuhisa Furuta et al.
Year), which is explained in detail by Ohmsha Co., Ltd.
Here, it may be designed as a minimum-dimensional observer or a finite settling observer according to the mode of the vehicle and its braking control device.

In this case, the ECU 40 is also estimated by the observed state variable quantity or the above observer. In addition, in the system expanded by using the cumulative value obtained by accumulating the deviation between the target rotational angular velocity of the wheel 1 calculated from the vehicle speed V and the rotational angular velocity detected by the rotational angular velocity sensor 15, both of them are predetermined. An optimal feedback amount is determined from the obtained optimal feedback gain and the actuator 31 is controlled. The cumulative rotation speed is calculated based on the calculated target rotation angular velocity V
It is a necessary amount because it decreases in a ramp function according to. That is, generally, in the control of the servo system, it is necessary to control so as to eliminate the steady deviation between the target value and the actual control value, and this needs to include 1 / S ^l (integral of order ¹ ) in the transfer function. To be done. Further, in the case of a control system such as a digital control in which the control amount can be determined only with finite accuracy, it is desirable to include the above integral amount from the viewpoint of control stability and noise stability. For this reason, this cumulative value is used. Therefore, the above Expand the system by adding this cumulative value to If the feedback amount is determined by and, the control amount to the controlled object, that is, the control amount of the brake hydraulic pressure of the wheel 1 is determined as the additional integral type optimum regulator.

Next, the optimum feedback gain will be described. In the optimum regulator to which the integral amount is added as described above, it has been clarified how to obtain the control input (here, various quantities of the brake hydraulic pressure control of the hydraulic brake device 11) that minimizes the evaluation function J, and the optimum feedback is obtained. The gain is also the solution of the Riccati equation and the state equation (a1) and the output equation (a2). And the weighting parameter matrix used for the evaluation function (see above, etc.). Where the weight Is initially given arbitrarily, and the evaluation function J changes the weight that restricts the behavior of the brake hydraulic pressure of the system that controls the braking of the vehicle. It is possible to determine an optimum value by giving a weighting parameter arbitrarily and performing a simulation by a large computer, changing the weighting parameter by a predetermined amount from the obtained behavior of the brake hydraulic pressure and repeating the simulation. Best result Is also defined.

Therefore, the ECU 40 of the braking control device of the present invention is configured as an additional integral type optimum regulator by using a predetermined dynamic model of the system related to vehicle braking, and observer parameters and optimum All of the above can be determined in advance by simulation.

If the ECU 40 is configured in this way, the rotational angular velocity of the wheel 1 is controlled to the target rotational angular velocity without causing overcontrol due to the response delay of the hydraulic system (RHS, etc.) that cannot be observed, and the desired slip ratio is obtained. Can be worked to achieve sufficiently accurately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of the basic configuration of the present invention, FIG. 2 is a graph showing the relationship between slip ratio and frictional force, and FIG. 3 is a schematic configuration diagram of an embodiment of the present invention. FIG. 4 is a block diagram showing the hydraulic system for the right front wheel together with the configuration of an electronic control unit (ECU), FIG. 5 is a flowchart showing the processing procedure in the embodiment of the present invention, and FIG. 6 is a brake pedal depression amount Bf and acceleration. A graph showing a table with βt, FIG. 7A shows a timing chart of the brake pedal depression amount, FIG. 7B shows a timing chart of deceleration, and FIG. 7C shows a timing chart of vehicle speed and wheel rotation speed. 1,2,3,4 …… Wheels 11,12,13,14 …… Hydraulic brake device 15,16,22 …… Rotation angular velocity sensor 24 …… Brake pedal 25 …… Brake sensor 31,32,33 …… Actuator 40 …… ECU 43 …… Hydraulic pressure generator 51,52,53 …… Hydraulic sensor 54 …… Accelerometer

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-51-123477 (JP, A) JP-A-57-194144 (JP, A) JP-A-60-45454 (JP, A)

Claims (1)

[Claims] 1. A brake operation amount detecting means for detecting a brake operation amount of a vehicle driver, an acceleration detecting means for detecting an acceleration of the vehicle, a brake pressure adjusting means for adjusting a brake pressure for braking a wheel, and Vehicle speed detecting means for detecting speed, rotational speed detecting means for detecting rotational speed of wheels, brake switch for detecting presence / absence of brake operation by a vehicle driver, vehicle speed detected by the vehicle speed detecting means, and the rotational speed Slip ratio calculating means for calculating the slip ratio from the wheel rotation speed detected by the detecting means, and the brake pressure adjusting means according to the comparison result of the slip ratio calculated by the slip means calculating means and the predetermined slip ratio. And a control means for controlling the slip ratio calculated by the slip ratio calculation means. If the slip ratio exceeds the predetermined slip ratio, the brake pressure adjusting means is controlled so that the brake pressure is reduced. If the slip ratio calculated by the slip ratio calculating means does not exceed the predetermined slip ratio, it is detected that the brake switch is operated. At this time, a target acceleration for the brake operation amount detected by the brake operation amount detecting means is obtained based on a predetermined pattern, and the brake pressure adjusting means is controlled so that the acceleration detected by the acceleration detecting means becomes the target acceleration. A vehicle deceleration control device that suppresses the brake pressure adjusting means so that the brake pressure is reduced when the brake switch detects that there is no brake operation.