JPS63270272A - Anti-skid controller - Google Patents

Abstract

PURPOSE:To simplify circuitry for detecting body acceleration by predicting body acceleration and body speed from braking force of a brake device, then regulating braking force of the brake device based on the predicted body speed and a wheel speed fed from a wheel speed detecting means. CONSTITUTION:A body speed detecting means M detects braking force of a braking device M2 through a brake force detecting means M6, then predicts body acceleration through a body acceleration predicting means M7 based on the detected brake force and the inertia mass of the body while furthermore predicts body speed. A control means 5 regulates brake force of the braking device M2 based on the predicred body speed and rotary speed of a wheel M2 detected through a wheel speed detecting means M3 so as to control slippage of the wheel M1 to a predetermined level for providing a high control efficiency. Consequently, anti-skid control can be carried out stably without providing an acceleration sensor to the body.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention controls the braking force of a braking device based on the vehicle body speed and the rotational speed of the wheels to prevent transient slippage of the wheels when braking the vehicle. The present invention relates to an anti-skid control device that prevents skids, and more particularly relates to an anti-skid control device that performs control by estimating the vehicle speed from vehicle acceleration.

[Prior Art] Anti-skid control devices reduce safety due to wheel openings and brakes during vehicle braking, such as locking of the front wheels of the vehicle, making it impossible to steer the vehicle, and locking of the rear wheels of the vehicle, which may cause the vehicle to sway (
In order to prevent the occurrence of skid), the slip ratio SL of each axle of the vehicle [(vehicle speed - wheel rotation speed)
/ This is to control the rotational speed of the wheels so that the coefficient of friction between the tires and the road surface is maximized by controlling the vehicle body speed to around 20%. It is configured to control the braking force of the provided braking device (ie, brake device).

Further, for detecting the vehicle speed, for example, Japanese Patent Laid-Open No. 61-89
As described in Japanese Patent No. 156, a method is adopted in which an acceleration sensor is provided on the vehicle body and the vehicle body acceleration detected by the acceleration sensor is integrally processed to obtain the vehicle speed. Note that the acceleration sensor uses the inertia of a pendulum or magnetic fluid to detect acceleration acting on the sensor.

[Problems to be Solved by the Invention] However, when detecting the vehicle speed using an acceleration sensor as described above, it is necessary to prevent the acceleration sensor from detecting acceleration due to rolling, pitching, yawing, etc. acting on the vehicle body. It is necessary to install the acceleration sensor near the center of gravity of the vehicle body, and it is troublesome to secure and adjust the mounting position. In addition, some kind of vibration is always acting on the car body while it is running, and the output of the acceleration sensor includes not only the car body acceleration but also the noise component of the vibration acceleration. However, there is a problem in that a signal processing device and a signal processing program must be provided to remove such noise components.

Therefore, the present invention has been made with the object of providing an anti-skid control device that estimates and controls vehicle body speed from vehicle body acceleration, so that vehicle body acceleration can be obtained with a simple configuration without providing an acceleration sensor on the vehicle body.

[Means for Solving the Problems] That is, the present invention, which has been made to achieve the above object, includes a braking device M that brakes the rotation of a wheel M1 pivotally supported on a vehicle body, as shown in FIG. 1, for example.
2, and wheel speed detection means M for detecting the rotational speed of the wheel M1.
3. and a vehicle speed estimating means M4 for estimating the vehicle speed, and at least the vehicle speed estimated by the vehicle speed estimating means M4 and the wheel M1 detected by the wheel speed detecting means M3.
The control r! is based on the rotational speed of r! Control 3 (1 means M5) for adjusting the braking force of the JJ device M2 and controlling the slip occurring between the wheel M1 and the road surface when the vehicle is braked; and a braking force detection means M for detecting the braking force of the braking device M2.
6, and a vehicle body acceleration estimating means M7 for estimating the vehicle body acceleration based on the braking force detected by the braking force detecting means M6, and configured to detect the vehicle body acceleration from the braking force of the braking device M2. The gist of this paper is an anti-skid control device that is characterized by:

Here, as the braking device M2, a hydraulic brake device that presses a friction member into contact with a member that rotates together with the wheel using hydraulic pressure, an electromagnetic brake device that brakes a magnetic body that rotates together with the wheel using electromagnetic force, etc. can be used. The braking force in the former is hydraulic, while in the latter it is an electrical quantity, such as a pulse or voltage.

The rotational speed detection means M3 is for detecting the rotational speed of the wheel M1, and may be an electromagnetic pickup type sensor or an optical sensor that outputs a pulse with a period proportional to the rotational speed.

Furthermore, the braking force detection means M6 is for detecting the braking force of the braking device M2, and if the braking device M2 is a hydraulic brake device, it is a hydraulic pressure sensor that detects the hydraulic pressure. A sensor or an electric circuit that detects the amount of electricity generated, or a means for storing the controlled amount output from the control means M5.

Next, the vehicle body acceleration estimation means M7 detects the vehicle body acceleration based on the braking force of the braking device M2 detected by the braking force detecting means M6. Hereinafter, the reason why the vehicle body acceleration can be estimated from the braking force of the braking device M2 will be briefly explained using FIG. 2.

First, the force F acting on the vehicle body when braking the vehicle is the sum of the forces f applied from each axis of the vehicle, and by dividing this by the inertial mass M of the vehicle body, the vehicle body acceleration Ma can be obtained.

Considering the force f of each axle of the vehicle acting on the vehicle body, the force f is given by the friction torque Tf acting due to the friction between the wheels and the road surface. Further, this friction torque Tf is given by the braking torque Tb acting by the braking force of the braking device and the rotation l and the torque Tr, based on the balance of torque around the wheels. Furthermore, this rotational torque T [is the rotational acceleration V obtained by time-differentiating the rotational speed Vw of the wheel.
Given based on wd.

Therefore, the vehicle body acceleration Ma is the rotational speed Vw of each axle of the vehicle.
and the braking force of the braking device.

If we consider here that the rotational speed Vw of the wheel is appropriately controlled, the rotational acceleration Vwd will be approximately constant.

Therefore, by anti-skid control, the wheel rotational speed Vw
In a vehicle that is controlled within the rotational range where the wheels do not lock, the vehicle body acceleration Ma can be determined only from the braking force of the braking device M2.

For this reason, the acceleration estimating means M7 experimentally determines the relationship between the vehicle body acceleration Ma and the braking force of the braking device M2 in advance, records the measurement results as a map or an arithmetic expression, and when executing control, the map or The vehicle body acceleration Ma may be estimated using an arithmetic expression.

Next, the vehicle speed estimating means M4 detects the braking force detecting means M6.
and a vehicle body acceleration estimating means M7, and estimates the vehicle speed V by integrating the vehicle body acceleration Ma estimated by the vehicle body acceleration estimating means M7.

Further, the control means M5 includes at least the vehicle speed estimation means M4.
The braking force is calculated based on the vehicle body speed estimated by and the rotational speed of the car @M1 detected by the wheel speed detection means M3. I!
] to control wheel slip to a predetermined value with good control efficiency. That is, the target rotational speed of the wheel M1 is calculated from the vehicle body speed estimated by the vehicle body speed estimating means M4, and the rotational speed of the wheel M1 is prevented from falling significantly below the target rotational speed when braking the vehicle, that is, the wheel M1 is prevented from locking. Then, the braking force of the braking device M2 is controlled.

The vehicle acceleration estimation means M7 and the vehicle speed estimation means M4
, and the control means M5, similarly to the conventional anti-skid control device, are constructed using a logical operation circuit centered on a microcomputer, and can be realized as one control process executed therein.

Further, the control means M5 may be configured to control the braking device M2 by feedback control based on conventional classical control, but the control means M5 may be configured to control the braking device M2 by feedback control based on conventional classical control. This can also be realized by feed pump control based on modern control theory, which calculates the braking force of the brake device of the wheel and controls the brake device M2.

[Operation] In the anti-skid control device of the present invention configured as described above, the vehicle body acceleration is estimated from the braking force of the braking device M2, and the vehicle body speed is estimated from the estimated vehicle body acceleration. The estimated vehicle speed is then manually input to the control means M5 together with the rotational speed of the wheel M1 detected by the wheel speed detection means M3, and based on the human power value, the braking device M20
Braking force is adjusted.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

Note that the following example shows one embodiment of the invention, and the present invention includes other embodiments as long as they do not depart from the gist.

FIG. 3 is a schematic configuration diagram showing the overall configuration of a vehicle anti-skid control device mounted on a four-wheeled vehicle as an embodiment of the present invention, and FIG. 4 is a block diagram of an electronic control unit showing the control system for the right front wheel. It is a control system diagram shown with a figure.

First, the overall configuration and the outline of the hydraulic system and electrical system will be explained.

As shown, each wheel of the vehicle 1. 2.3. 4 is a hydraulic brake device 11°12.1 corresponding to the braking member M2.
3.14, and electromagnetic pink-up type wheel speed sensors 15.16 are attached to the right and left front wheels 1.2 to detect the respective rotational speeds. Further, the rotational speeds of the rear wheels 3 and 4, which rotate in response to the rotation of the output shaft 19 of the transmission 18 via the differential gear 21, are detected by a rear wheel speed sensor 22 provided in the transmission 18.

Hydraulic brake devices 11 to 14 provided on each wheel brake the rotation of each wheel 1 to 4 using high hydraulic pressure generated by a tandem type mask cylinder 25 linked to a brake pedal 24 as brake oil pressure. The hydraulic pressure is adjusted by actuators 31, 32, and 33 transmitted from the mask cylinder 25 via the hydraulic system MPS. The actuators 31, 32, and 33 independently adjust the brake oil pressure of the front right wheel 1, the front left wheel 2, and the left and right rear wheels 3 and 4, and are controlled by an electronic control unit (ECU) 40.

The hydraulic pressure of the hydraulic system RH3 for brake hydraulic pressure to the right front wheel 1 is determined by the hydraulic pressure sensor 51, and the hydraulic pressure of the hydraulic system RH3 of the left front wheel 2 is transmitted to the hydraulic system L E-I of the left front wheel 2.
The oil pressure of S is detected by the oil pressure sensor 52, and the oil pressure of the hydraulic system BH5 of the rear wheels 3.4 is detected by the oil pressure sensor 53.

In addition to signals according to the oil pressure from these oil pressure sensors 51, 52 and 53, the ECU 40 also sends signals from wheel speed sensors 15, 16
．． wheel speed signals from 22 and further brake pedal 2
4, the actuators 31, 32, 33 are each controlled (that is, the braking force of each hydraulic brake device 11 to 14 is controlled), and each wheel 1 is Control the rotation speed of ~4.

Since the braking forces of the right front shaft 1, the left front wheel 2, and the rear wheels 3 and 4 are controlled independently, the right front wheel @1 will be explained below. FIG. 4 is a block diagram mainly showing the system for controlling the braking of the right front wheel 1. As shown in the figure, the ECU 40 includes a power supply unit 58 that receives power supply voltage from a battery 57 via an ignition gear 56 and supplies a constant voltage to the entire unit, and includes a well-known CPU 61, R0M63, RAM6
It is configured as a logic operation circuit in which an output port lower, an analog manual port 9, a pulse manual port 1, etc. are connected to each other by a bus 72, centering on a port 5, etc.

On the other hand, the actuator 31 includes a bypass valve 73 and a three-position valve 74. The bypass valve 73 is connected to the mask cylinder 2
5 and the hydraulic brake device 11, and this oil path is shut off by a command from the ECU 40.

The three-position valve 74 has a first device a that holds the hydraulic pressure of the hydraulic brake device 11, a second device that increases the hydraulic pressure of the hydraulic brake device 11, and a third device C that reduces the pressure of the hydraulic brake device 11. and is normally biased to the second position.

The hydraulic pressure generator 43 pressurizes the brake oil in the reservoir 43a with the pump 43b and supplies it to the three-position valve 74 via the pressure accumulator 43C. The high oil pressure from this oil pressure generator 43 is applied to the hydraulic brake device 1 at the second position of the three-position valve 74.
1. In the third device C of the three-position valve 74, the hydraulic pressure of the hydraulic brake device 11 is released to the reservoir 43a.

In the hydraulic brake device 11, the piston 75 is pushed out by the supplied hydraulic pressure, and the brake pad 76 is brought into contact with the disc plate 77 that rotates together with the vehicle @1, thereby braking the rotation thereof. 80a, 80b in the southern circuit,
80c is an orifice, 81a, 81b, 81c, 81d
, 81e are check valves.

Here, an outline of the operation of the control system shown in FIG. 4 will be described.

When the driver depresses the brake pedal 24, hydraulic pressure is generated in the mask cylinder 25, this hydraulic pressure is transmitted to the hydraulic brake device 11 via the bypass valve 73, and the wheels 1 are braked.

When this braking force is strong and the wheels 1 are on the verge of locking, and the slip ratio exceeds a predetermined value, the ECU 40 detects this,
Start anti-skid control.

First, the pump 43b is driven, but this pump may be a constantly operating cylinder 11 so as to keep the pressure of the pressure accumulator 43c constant. driving the bypass valve 73 to the second position;
The direct connection between the mask cylinder 25 and the hydraulic brake device 11 is cut off. Thereby, the mask cylinder 25 and the hydraulic brake device 11 are connected to the three-position valve 74 and the orifices 80a, 80a.
0b.

Thereafter, while the brake pedal 24 is depressed, the ECU 40 calculates a target rotational speed Vw'' that allows the vehicle to be braked in the shortest distance, and applies a command oil pressure to match the rotational speed Vw of the car @1 with the target rotational speed Vw'. 3 position valve 74 by calculating
to drive. The three-position valve 74 is controlled by switching between the first device a, the second position, and the third device C, and maintains, increases, and decreases the hydraulic pressure of the hydraulic brake device 11 to brake the Controls hydraulic pressure to command hydraulic pressure.

In addition, in this embodiment, the braking device M2 is the hydraulic brake device 1.
1, and its braking force is substituted by the oil pressure of the hydraulic brake device 11.

Next, the control by the ECU 40 will be explained in more detail.

First, the braking system of the vehicle will be explained based on FIGS. 2 and 5. As mentioned above, FIG. 2 is a diagram illustrating the forces acting between the vehicle body, wheels, and road surface, and FIG. 5 is a block diagram modeling the braking system. In the following explanation of the block diagram, the operation 1/S represents time integration, and the operation S represents time differentiation.

When the ECU 42 commands the hydraulic pressure prs, the hydraulic servo causes the hydraulic brake system to output pr.

Hydraulic pressure is supplied.

The hydraulic brake device generates a braking torque Tb to brake the wheels. This braking torque Tb is determined from a coefficient Kt determined from the structure and characteristics of the hydraulic brake device and oil pressure pro.

On the other hand, the wheels are rotating at a speed Vw, and the vehicle body is rotating at a speed ■
I am exercising with.

The value obtained by dividing the difference between the rotational speed Vw and the vehicle speed V by the vehicle speed ■ becomes the slip ratio SL, and the friction coefficient μ between the road surface and the wheels is determined by a nonlinear operation.

The friction torque Tf that the wheel receives from the road surface is determined from this friction coefficient U, the vehicle body mass m for the negative axis, the gravitational acceleration G, and the effective radius r of the wheel.

The difference between the friction torque Tf and the braking torque Tb becomes the rotational torque Tr acting on the wheel.

The rotational acceleration Vwd of the wheel is determined from this rotational torque Tr, the effective radius r of the wheel, and the rotational moment of inertia (I) of the wheel, and the integral of this is the rotational speed Vw.

On the other hand, f acting on the axle is determined from the friction coefficient μ, the vehicle body mass m for the negative axis, and the gravitational acceleration G.

Since this force f is the force that the vehicle body receives from one wheel, the force F that acts on the vehicle body is the sum of the forces that are received from all wheels, and the force F that acts on the vehicle body is determined.

By dividing the force F acting on the vehicle body by the vehicle mass M, the vehicle body acceleration Ma is determined, and by integrating this vehicle body acceleration Ma, the vehicle body speed V is determined.

Therefore, as described above, the vehicle body acceleration Ma is determined by the rotational speed Vw of each wheel detected by the wheel speed sensors 15, 16, 22, and the oil pressure sensor 51. It can be estimated from the brake oil pressure pro of each hydraulic brake device detected by 52.53. In other words, the friction torque Tf that each wheel receives from the road surface is expressed by the following formula (1% formula %) Since the force f that the vehicle body receives from this wheel is expressed by the following formula (2), f=Tf/r... (2) In the case of a four-wheeled military vehicle as in this example, the force F that the vehicle body receives from all wheels is as shown in the following equation (3), F=fFR+fFL+fRR+fRL
(3) Vehicle acceleration Ma can be obtained by the following equation (4).

M a = F / M...
・(4) However, fFR is the right front wheel, fFL is the left front wheel, fR
R indicates the force of the right rear wheel, and fRL indicates the force of the left rear wheel.

By the way, in this embodiment, the rotational speed Vw of each wheel is appropriately controlled by anti-skid control, which will be described later, so that the wheels do not lock, so that the rotational acceleration Vwd of each wheel is
is almost a constant value. Therefore, if Vwd in the above equation (1) is constant, the above equation (4) will finally become Ma= (PF'R0PFL+PRR0PRL)
In order K 1+, 2...(4)' becomes. However, PFR is the right front wheel, PFL is the left front wheel,
PRR indicates the brake oil for the right rear wheel, PRL indicates the brake oil for the left rear wheel,
2 indicates a constant in Kl.

Therefore, the vehicle body acceleration Ma was measured when the vehicle was actually driven and the wheels were braked while gradually applying hydraulic pressure to each hydraulic brake device, and as a result, data as shown in FIG. 6 was obtained. Therefore, by having this measurement data as a map and using the oil pressure data obtained by the oil pressure sensor at high speed, the vehicle body acceleration Ma can be estimated with almost no error. In FIG. 6, Pa1l indicates the total oil pressure of each hydraulic brake device.

Next, a control system using the ECU 40 will be explained.

In this embodiment, state feedback is performed using an optimal regulator based on modern control theory.

Therefore, the optimal feedback method of this embodiment will be briefly explained. Modern control theory is explained in detail in, for example, Katsuhisa Furuta's ``Linear System Control Theory'' (1978, Shoshodo) and Katsuhisa Furuta's ``Mechanical System Control'' (1980, Ohmsha), etc. Therefore, we will not explain in detail the derivation of the equation or other methods. Also, in the following explanation, x, y, u, A, B, C, F, S, Q
,R.

G1. G2, etc. represent vector quantities (matrix), AT represents the transposed matrix of A, and A-'I represents the inverse matrix of A, respectively.

In this embodiment, the control system is composed of an ECU 40, and samples (+fI) are sampled at predetermined time intervals.
It is a system. In such a sample value system, let X(k) be the state variable representing the internal state of the controlled object, u(k) be the control human power amount for the controlled object, and y(k) be the control output amount for the controlled object. ), these relationships are expressed by the following equations (5) and (6).

x(k+1) =A-x(k) +IB-u(k)
=-(5)y (k) = C-x(k)
(6) Note that the subscript indicates the sampling time, and k+1 indicates the next sampling time.

Here, if the dynamic model of the controlled object is clarified and the vectors A, E, and C can be clarified, then the state change amount x (k), the control output y (k), and the control target y'' (k), the feedback ff1F can be found, and the control input quantities 111 (k) for controlling the control output y (k) to the control target y'' (k) can be found, and the controlled object can be optimally controlled. can.

The dynamic model of the controlled object, ie, the control system, of this embodiment is as shown in FIG. 5 mentioned above, based on the equation of motion. In addition, in this embodiment, since control is required to eliminate the steady-state deviation between the target (direct) and actual control output values of the control output, the integral value of the difference between the target value and the output value is set as the state variable ff1x (
In addition to k), expand the system. Therefore, in this embodiment, state variable quantity x(k), control human power u(k), control output y(k
), the following equations (7) and (8).

It shall be handled as shown in (9).

u(k) = [pr s]...
(8) y(k) = [Vw co
...(
9) Next, the optimal feedback gain F will be explained. In this example, the optimal feedback gain F is calculated by the following formula (
10).

F=-(R+ET-5-B)-'-E'-5-A-(10)
Note that S is a solution of the Glue Ricci equation in the following equation (11).

5=Ar-S-A-AT-S-E (B'-S◆B+I
R) -1・8 guns・S−A+Q・Be11) Here, Q and IR are the parameter meters selected as the optimal values in a computer simulation that minimizes the evaluation function J of the following equation (12). .

J=Σ[x'(k+1)・Q−x(k+1)K=8+u”(k+1)・R−u(k+1)co−(12
) In this example, the parameters Q and IR of the evaluation function J were changed and computer simulations were repeated, and the optimal parameters were determined from the behavior of the braking system obtained in the simulation, and the optimal feedback gain F was determined.

Once the optimal feedback gain F is determined in this way, the control human power u(k+1) is calculated using the following equation (13).

to L (k+1) = −F −x (k+1)
...(13) However, due to the response delay of the control system, x(k+1) cannot be used directly. Therefore, by substituting the right side of equation (5) above, the control human power u(k
+1) is obtained from the following equation (14).

u(k+1)=-(F-A-x(k)+F4N3-u(k)
) -(14) Here, when G1=FA and G=FE, the above equation (14) becomes the following equation (15).

u(k+1)=-(G1・x(k)+G2''u(k))=(
15) Therefore, from the values of F, A, and E, the above G1 and G2
By setting , it becomes possible to determine the control human power, that is, the command hydraulic pressure prs to the hydraulic brake system.

It is also possible to obtain G1 and G2 in advance according to the vehicle speed and to switch between them according to the vehicle speed.

For example, each of the above parameters can be set so that the speed of convergence of the system becomes slower as the vehicle speed decreases.

Next, FIG. 7 shows a block diagram of the control system of this embodiment configured as described above.

As shown in the figure, hydraulic pressure is supplied to the control system from a hydraulic servo, and the supplied hydraulic pressure pro and rotational speed Vw are detected by a hydraulic pressure sensor and a wheel speed sensor, respectively. Then, the output flu V w from the heavy wheel speed sensor is converted into a rotational acceleration Vwd by differentiating it with respect to time.

In addition, the output fipro of the oil pressure sensor is added together with the output value pro from other oil pressure sensors, and is converted to the car body acceleration Ma based on the map showing the relationship between the brake oil pressure and the car body acceleration as shown in FIG. Vehicle acceleration Ma
The vehicle body speed V can be determined by integrating .

Then, from this determined vehicle speed ■, a target rotational speed Vw' is determined with the slip rate at which the vehicle is braked most efficiently as 20%, and this target rotational speed Vw'' and the detection value Vw of the wheel speed sensor are determined. INTΔVw is obtained by integrating the difference ΔVw.

Furthermore, the output value from the wheel speed sensor (i.e., the rotational speed of the wheel) obtained as described above Vw, and its acceleration V
w d and the product i of the difference from the target rotational speed Vw'
The command oil pressure prs is obtained by multiplying I N T ΔVw and the previous command oil pressure prs by the optimum feedback gain F.

On the other hand, the detection value Vw of the wheel speed sensor is converted into the wheel acceleration Vwd by differential operation, and is converted into the wheel rotational torque Tr from the wheel effective radius r and rotational inertia moment) I. , is converted into a braking torque Tb acting on the wheels from a coefficient Kt determined from the structure and characteristics of the hydraulic brake system.Then, based on these rotational torque Tr and braking torque Tb, the starting hydraulic pressure calculating section performs anti-skid control. The command oil pressure prs at the initial stage of the start is calculated.

Next, a flowchart of the ECU 40 that implements the above control system will be described.

The flowchart in FIG. 8 shows anti-skid control by the ECU 40. In addition, in ECU40, the 7th
In addition to the anti-skin control shown in the figure, each sensor and ECU
It also executes processing for self-diagnosing failures such as 40, etc., and starts operation when the power is turned on using the ignition key installed in the vehicle.

When the process is started, step 100 is first executed to initialize the memory area used for the anti-skid control and to set initial values for each memory.

In step 110, it is determined whether control is to be started.

In this embodiment, when the slip rate becomes 8% or more, it is determined that control is to be started, and the process branches to YES. Here, the conditions for this slip ratio of 8% include the fact that the control target is 20%, the response delay of the hydraulic servo from the start of control, and the high U.
This was determined in consideration of the fact that on roads, it is not desirable to start anti-skid control unless braking is very sudden, but on low-U roads, it is desirable to start anti-skid control as soon as possible.

In step 120, the initial command oil pressure pr immediately after the start of control is
s is calculated, and the process proceeds to step 130, where a valve position for supplying the initial command oil pressure prs is commanded.

In step 140, the rotational speed Vw of each wheel is manually determined from the wheel speed sensor 15.16.22.

In step 150, the rotational acceleration Vwd of each wheel is calculated from the rotational speed Vw of each wheel using the following equation (16).

Vwd(k+1)=(Vw(k+1)−Vw(k))/T −=(1
6) Here, T is the sampling period of the rotational speed Vw, and is the time until the process of step 140 is executed again. In the following explanation, T represents this time.

In step 160, the hydraulic brake system 11.1 of each wheel is adjusted based on the output signal from the hydraulic pressure sensor 51.52.53.
2. The hydraulic pressure pro (specifically Pfr, Pfl, Prr) supplied to 13 and 14 is manually operated.

In step 170, the read oil pressures prO supplied to each of the hydraulic brake devices 11 to 14 are added together, and the vehicle body acceleration Ma is calculated from the map shown in FIG.

That is, the oil pressure sensor 51 read in step 160 above.
Based on the output signal from 52.53, the total hydraulic pressure Pa1l supplied to each of the hydraulic brake devices 11, 12, 13, and 14 is calculated using the following equation (17), and a preset map is calculated based on the calculation result. From vehicle acceleration M
It calculates a.

Pa1l=Pf r+Pf 1+2・Prr −(1
7) At step °180, at step 170? The vehicle body speed V is calculated from the calculated vehicle body acceleration Ma using the following equation (18).

V (k+1) = V (k) + M a (k)
-T - (1B) In step 190, the target rotational speed Vw'' at which the vehicle can be braked efficiently is calculated from the following equation (19).

Vw”=V ◆(1-S L) =-
(19) Note that SL is the slip ratio, and if the slip ratio at which the frictional force is the largest (20% in this embodiment) is set, the most efficient braking will be achieved. Further, this slip ratio SL may be made variable depending on the vehicle speed at the time of starting braking.

In step 200, the integral value INTΔVw of the rotational speed Vw of each wheel is calculated using the following equation (20).

INT△Vw(k+1)=INT△Vw(k)+△Vw(k)・T...(20
) In step 210, the command oil pressure prs for each wheel is calculated. Since the command oil pressure prs corresponds to the control human power, it can be obtained from the above-mentioned equation (15) by the following equation (21).

p r s (k+1)=-(G 1 ・x(k)+62 ・pr
s (k)) - (21) In step 220, three-position valves corresponding to the right front wheel, left front wheel, and rear wheel are controlled in order to control the brake oil pressure of each wheel based on the command oil pressure prs of each wheel. A pattern is selected and the three position valve is commanded. Note that in actual step 220, the command is issued at the next sampling time (before step 140) based on the command oil pressure obtained this time, so the response delay of the actual control system can be taken into account.

That is, the three-position valve is driven so that the brake oil pressure of each wheel becomes the command oil pressure p r s (k+1) for each wheel during the sampling time T.

In step 230, 1 (1) indicating the sampling time point is
Increment by

In step 240, it is determined whether or not to continue anti-skid control. For example, the determination is made based on whether the brake pedal is depressed or not and whether the vehicle has stopped. If the vehicle is to be continued, the process returns to step 140; if not, the current anti-skid control is ended and step 140 is determined. 1
10.

As explained above, this embodiment is configured to detect the oil pressure of the hydraulic brake system, estimate the vehicle acceleration from the detection result, and obtain the vehicle speed. Therefore, the vehicle speed can be detected without providing an acceleration sensor on the vehicle body, and can be realized with a simple circuit configuration without providing a processing circuit or the like for processing output signals from the acceleration sensor as in the past. If the road surface suddenly changes during control, for example if you jump from asphalt to a frozen road surface, the control hydraulic pressure may become too large and the wheels may lock.In this case, the ECU 40 will send the command hydraulic pressure PRS Since 0 is instantaneously output and the actual control oil pressure also quickly becomes a small value, it is possible to estimate the vehicle body acceleration Ma from the oil pressure of the hydraulic brake system without producing an error large enough to cause problems in control.

In the above embodiment, the present invention is applied to a rear wheel drive vehicle, but it can of course also be applied to a front wheel drive or four wheel drive vehicle, or a uniaxially driven two or three wheel vehicle.

Further, in the above embodiment, the front two wheels are controlled independently and the rear two wheels are controlled collectively, but all wheels may be controlled independently.

Furthermore, in the above embodiment, the vehicle body acceleration is defined as the sum of the forces exerted by each wheel on the vehicle body, and the total oil pressure P of each hydraulic brake device is calculated as follows:
Although it was configured to be calculated from a1l, the force applied by each wheel to the car body is calculated for each car from the hydraulic pressure of each hydraulic brake device, the acceleration applied to the lower body of each force is calculated, and this is combined at the center of gravity of the car. Even with such a configuration, it is possible to estimate the vehicle body acceleration well. With this configuration, the direction of vehicle acceleration can also be determined.

Further, in the above embodiment, the hydraulic pressure-torque conversion coefficient Kt of the hydraulic brake device was explained as a fixed value, but this coefficient rAKt
changes depending on the condition of the friction members, weather environment, etc., so the ECU
may be configured to be calculated empirically. For example, during string braking where the slip rate does not increase much, that is, anti-slip
The map correction gain K may be calculated from the oil pressure and rotational acceleration when the command control is not executed and CP[J has a calculation surplus. In this case, the arithmetic expression in step 173 becomes Ma=-f (Pall).

Further, in the above embodiment, the braking system is controlled by performing optimal feedback based on modern control theory, but feedback control may also be performed based on classical control, and the braking system can be controlled using various conventionally known control methods. The following method can be applied.

Further, the braking device is not limited to a hydraulic brake device, but may be one that adjusts the magnitude of frictional force using electromagnetic force.

[Effects of the Invention] As described in detail above, the anti-skid braking device of the present invention is configured to estimate the vehicle acceleration based on the braking force of the braking device provided on the wheels and to determine the vehicle speed. Therefore, the vehicle body acceleration can be determined without providing an acceleration sensor on the vehicle body as in the conventional case, and the circuit configuration for detecting the vehicle body acceleration becomes simple.

In addition, the braking force detected by the braking force detection means is determined by the responsiveness,
This is a suitable parameter for performing anti-skid control with good stability, and the control is executed by the control means together with the vehicle speed estimated by the vehicle speed estimation means, the wheel rotation speed detected by the wheel speed detection means, etc. It can also be used for.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is an explanatory diagram illustrating the forces acting on the wheels and the vehicle body when braking a vehicle, and FIG. 3 is a configuration showing the overall configuration of the anti-skid control device of the embodiment. Figure 4 is a block diagram showing the configuration related to the right front wheel in detail, Figure 5 is a block diagram showing a dynamic model of the braking system of the embodiment, and Figure 6 is the brake oil pressure and lower body acceleration of the hydraulic brake system. 7 is a block diagram showing the braking system of the embodiment, and FIG. 8 is a flowchart 1 showing the anti-skid control process executed by the ECU 40.
・It is. Ml, 1.2, 3.4... Wheel M2... Braking device (11, 12, 13, 14... Hydraulic brake device) M
3... Wheel speed detection means (15, 16, 22... Lower wheel speed sensor) M4...
Vehicle speed estimation means M5... Control means M6... Braking force detection means Ml... Vehicle acceleration estimation means 40... Electronic control unit

Claims (1)

[Scope of Claims] A braking device that brakes the rotation of a wheel pivotally supported on a vehicle body, a wheel speed detection device that detects the rotational speed of the wheel, a vehicle speed estimation device that estimates a vehicle speed, and at least the vehicle body. The braking force of the braking device is adjusted based on the vehicle body speed estimated by the speed estimating means and the rotational speed of the wheel detected by the wheel speed detecting means, and the slip occurring between the wheel and the road surface when braking the vehicle is reduced. In the anti-skid control device, the vehicle speed estimating means includes a braking force detecting means for detecting a braking force of the braking device, based on the braking force detected by the braking force detecting means An anti-skid control device comprising: a vehicle body acceleration estimating means for estimating vehicle body acceleration, and configured to detect the vehicle body acceleration from the braking force of the braking device.