JPH082286A - Speed control device for vehicle - Google Patents

Abstract

PURPOSE:To cope with change of characteristics of a subject to control automati cally and speedily by determining a deceleration coefficient of a vehicle based on a car speed etc. correcting a desired brake pressure determined by an inverse number of it and a desired deceleration in accordance with difference from a real deceleration, and controlling a brake pressure adjusting means. CONSTITUTION:Signals of sensors 2, 6, 7 for a car speed, an axial load, and a steering angle are inputted into a controller 10 as well as a signal of a radar device 1. This controller 10 determines a deceleration coefficient of a ratio of a celeration of a vehicle to a brake pressure based on the car speed, the axial load, and the steering angle, and it determines a desired brake pressure based on an inverse number of it and a desired deceleration. This desired brake pressure is corrected in accordance with a difference from a real deceleration obtained by the desired deceleration and the car speed, a throttle valve is actuated by a throttle valve actuator 4 through a motor drive circuit 12, and a wheel cylinder is controlled by a pressure control valve 5 through a D/A converter 13. A desired acceleration/deceleration can thus be achieved speedily, thereby change of characteristics of a subject to control can be coped with automatically and speedily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control device, and more particularly to a vehicle speed control for controlling a constant speed running control and a vehicle-to-vehicle distance between a host vehicle and a preceding vehicle (hereinafter referred to as a front vehicle). It relates to the device.

[0002]

2. Description of the Related Art Conventionally, a constant speed that automatically adjusts the opening of a throttle valve as an engine output adjusting means so that the speed of a vehicle can be kept constant even if a driver does not operate an accelerator pedal. Vehicles equipped with a traveling device (auto cruise) are becoming popular.

In such a constant-speed traveling device, there is a possibility of a rear-end collision with the preceding vehicle due to traffic congestion on the road. For the purpose of preventing such a rear-end collision, the vehicle-interval distance with the preceding vehicle is detected and a predetermined safe inter-vehicle distance is set. Keeping devices have been developed.

A vehicle speed control device for maintaining a constant speed running and a safe inter-vehicle distance in this way has already been disclosed by the present applicant in Japanese Patent Application No. 4-111518, which will be described.

<Explanation of Japanese Patent Application No. 4-111518> FIG.
4 shows an example of a vehicle speed control device according to No. 4-111518. In this example, a radar device is used as the inter-vehicle distance detecting means 1 and a vehicle speed sensor is used as the own vehicle speed detecting means 2. An acceleration sensor is used as the vehicle acceleration detecting means 3.

A throttle valve actuator connected to a throttle valve (not shown) is used as the engine output adjusting means 4, and a pressure control valve connected to a wheel cylinder (not shown) is used as the brake pressure adjusting means 5. Is used.

Further, a controller 10 composed of a microcomputer is used, and an A / D converter 1 is provided between the controller 10 and the vehicle speed sensor 2 and the acceleration sensor 3.
1 and the motor drive circuit 12 between the throttle valve actuator 4 and the D / A between the pressure control valve 5 and
A converter 13 is provided.

The controller 10 in such an embodiment
6 shows a control program executed in step S1. First, the controller 10 drives the radar device 1 to read the data D regarding the inter-vehicle distance (step S).
1). The controller 10 also sets the vehicle speed V from the vehicle speed sensor 2 and the current acceleration / deceleration Y _P from the acceleration sensor 3 to A
The data is read via the / D converter 11 (step S2).

After this, the controller 10 performs step S1.
The relative speed A is calculated based on the inter-vehicle distance D read in (step S3). This can be obtained by differentiating the inter-vehicle distance D at constant time intervals as shown.

Next, the controller 10 obtains the safe inter-vehicle distance D _S from the vehicle speed V and the relative speed A (step S).
4). For the safe inter-vehicle distance D _S , the function f (V) for the vehicle speed V is calculated, the function g (A) for the relative speed A is calculated, and these functions f (V) and g (A) are added. It is calculated by

Next, the required acceleration / deceleration X is calculated from the relative speed A calculated in step S3 (step S
5). The acceleration / deceleration X is calculated using the relative speed A
Can be calculated from a map chart in which the horizontal axis is taken and the vertical axis shows the required acceleration / deceleration X.

In this way, after calculating the required acceleration / deceleration X, the safe inter-vehicle distance D _S and the actual inter-vehicle distance D, the target acceleration / deceleration Y is calculated based on these (step S
6). The acceleration / deceleration Y is Y = X + k as shown in the figure.
(D _S -D) (k is a constant) can be calculated by,
For example, in the case of acceleration, it has a positive value, and in the case of deceleration, it has a negative value.

Thereafter, it is determined whether or not the target acceleration / deceleration Y is a value that can be adjusted by the engine output (step S).
7). That is, as shown in the figure, the target acceleration / deceleration Y obtained in step S6 is (not including the polarity) more than the maximum deceleration Y ₀ (for example, -3 m / sec ² ) that can be handled when the throttle valve is controlled by the throttle valve actuator 4. It is determined whether the brake pressure is generated and adjusted (steps S8 to S10) or the engine output is adjusted (steps S11 to S13) by determining whether or not it is large.

Therefore, in step S7, when it is found that the target acceleration / deceleration Y is lower than the maximum deceleration Y ₀ that can be handled by the throttle valve, the braking force cannot be adjusted by the throttle valve, so the procedure for actually applying the brake is as follows. First, the controller 10 fully closes the throttle valve by the throttle valve actuator 4 via the motor drive circuit 12 (step S8). Then, after that, the compensation calculation of the brake pressure is performed (step S9).

The brake pressure compensation calculation in step S9 is executed by the procedure concretely shown in FIG.

That is, the target deceleration Y calculated in step S6 (in this case, Y is a small value Y <Y ₀ ,
It is deceleration, not acceleration. ) Is calculated (step S21). This is to calculate the input voltage E _ref to the pressure control valve 5 obtained by multiplying the target deceleration Y by the constant M.

On the other hand, the above target deceleration Y is calculated in step S2.
Actual deceleration as well as calculation as 1
It is necessary to compensate the brake pressure due to the relationship with
Is the target deceleration Y and the actual deceleration measured by the acceleration sensor 3.
Speed Y_PDifference ΔY = Y−Y _P(Step S
22). Then, multiply the difference value ΔY of this deceleration by a constant N.
To obtain the value N · ΔY for adjusting the control characteristics
(Step S23).

Then, the manipulated variable (voltage) E _ref calculated in step S21 is added to the adjustment value N · ΔY of the control characteristic to obtain a control value E _ref ′ = E _ref + N · ΔY (step S24).

The control value E _ref 'obtained in this way is D /
By giving the pressure control valve 5 via the A converter 13, the controller 10 can perform the actual brake pressure operation to the wheel cylinder (step S10).

On the other hand, when it is found in step S7 that the target acceleration / deceleration Y is larger than the maximum deceleration Y ₀ that can be handled by the throttle valve, the controller 10 first sets D
The brake pressure to the wheel cylinder is turned off by the pressure control valve 5 via the / A converter 13 (step S1).
1).

Since the engine output is adjusted this time, the compensation calculation of the throttle valve opening is performed (step S1).
2). This throttle valve opening compensation calculation can go through the same calculation procedure as the brake pressure compensation calculation shown in FIG.

For example, when accelerating the vehicle, the target deceleration Y in FIG. 7 becomes the target acceleration (Y is positive), which is shown in step S24 from the relationship with the acceleration Y _P actually measured by the acceleration sensor 3. The control value E _ref ′ can be determined, so that the throttle valve actuator 4 via the motor drive circuit 12 controls to actually open the throttle valve.

[0023]

In the above, the problem in the case of calculating the target acceleration / deceleration and actually operating the brake pressure is that if the hydraulic brake is taken as an example, the brake hydraulic pressure and the deceleration are in a simple proportional relationship. It is not in.

That is, when the vehicle speed at the start of braking is the same, the hydraulic pressure and the deceleration are in a substantially proportional relationship as shown by the solid line characteristics in FIG. 8, but in reality the vehicle speed at the start of braking, the vehicle weight, the steering angle, etc. It depends on various main factors (Fig. 8
Dashed line characteristics).

However, since the constant M in step S21 of FIG. 7 is fixed to a constant representative value, even if the above feedback control is performed, it cannot be compensated if the error becomes too large.

That is, in the compensation by the measured deceleration, the deviation is about 10 to 20%, but the load of the rear vehicle of the truck is about + 300% in the loaded vehicle compared to the empty vehicle, which cannot be dealt with. was there.

Therefore, an object of the present invention is to perform automatic deceleration control in consideration of various factors during brake operation in a vehicle speed control device for automatic deceleration control based on a calculated or set target deceleration. .

[0028]

To achieve the above object, in a vehicle speed control device according to the present invention, a vehicle speed detecting means, a means for detecting the front and rear axle weight of the vehicle, a steering angle detecting means, A brake pressure adjusting means, a deceleration coefficient indicating a ratio of the vehicle deceleration and the brake pressure is obtained from the vehicle speed, the front and rear axle weights, and the steering angle, and a target brake pressure is calculated from the reciprocal of the deceleration coefficient and the target deceleration. A means for correcting the target brake pressure according to the difference between the target deceleration and the actual deceleration obtained from the vehicle speed to control the brake pressure adjusting means to control the target deceleration. Is equipped with.

The above speed control device for a vehicle is provided with means for detecting an inter-vehicle distance between the front vehicle and the own vehicle, and the control means calculates a relative speed between the front vehicle and the own vehicle from the inter-vehicle distance,
The safe inter-vehicle distance can be calculated from the vehicle speed and the relative speed, the required acceleration can be further calculated from the relative speed, and the target deceleration can be calculated from the acceleration, the safe inter-vehicle distance, and the inter-vehicle distance.

[0030]

In the vehicle speed control device according to the present invention,
The brake pressure adjusting means, the vehicle speed detected by the vehicle speed detecting means, the front and rear axle weight (vehicle weight) detected by the means for detecting the front and rear axle weight of the vehicle, and the steering angle detected by the steering angle detecting means reduce the vehicle. Determine a deceleration coefficient that indicates the ratio of speed to brake pressure. This corresponds to the slope of the characteristic graph shown in FIG.

A target brake pressure is obtained from the reciprocal of the deceleration coefficient thus obtained and the target deceleration, and the target brake pressure is determined according to the difference between the target deceleration and the actual deceleration obtained from the vehicle speed. The brake pressure adjusting means is corrected and controlled.

As a result, a braking action corresponding to the target deceleration can be obtained.

The above-mentioned target deceleration can be simply set, but can also be calculated as described below by calculation as described in the conventional example.

That is, the relative speed between the front vehicle and the own vehicle is calculated from the inter-vehicle distance detected by the means for detecting the inter-vehicle distance between the front vehicle and the own vehicle, and the safe inter-vehicle distance is calculated from the relative speed and the above vehicle speed. Then, the required acceleration is further calculated from the relative speed, and the target deceleration can be calculated from the acceleration, the safe inter-vehicle distance, and the inter-vehicle distance.

[0035]

1 shows an embodiment of a vehicle speed control device according to the present invention. In this embodiment, in the conventional vehicle speed control device shown in FIG. And the steering angle sensor 7 is provided and connected to the A / D converter 11. The acceleration sensor 3 shown in FIG. 5 is not used for obtaining the acceleration from the output signal of the vehicle speed sensor 2, but it goes without saying that this acceleration sensor may be used.

Controller 10 in such an embodiment
Control program (acceleration / deceleration compensation routine)
Is shown in FIG. However, this control program
The only difference is that step S14 is added to the control program of FIG. 6 and that the brake pressure compensation calculation in step S9 is improved.
Therefore, in the following description, step S14 and step S9 will be performed, and the other description will be omitted.

FIG. 3 shows a flow chart for calculating the deceleration coefficient K _AP of FIG. 2 (step S14). In this flow chart, first, the controller 10 is operated.
Is the compensation coefficient K _V from the vehicle speed V read in step S2.
Is calculated (step S141). The calculation of the compensation coefficient K _V can be obtained by preparing a correction map for the vehicle speed as shown in the figure through experiments or the like (step S141).

Next, whether the vehicle speed V is higher than "0",
That is, it is determined whether the vehicle is moving (step S14
2) When V> 0, the controller 10 reads the axial loads W _{f and} W _r detected by the axial load sensors 6 for the front and rear wheels (step S143).

Then, another compensation coefficient K _W is calculated from the axial weights W _{f and} W _r (step S144). Also in this case,
In calculating the compensation coefficient K _W, a constant A _W,
B _{W and} C _W are calculated and K _W = A _W × W _f + B _W ×
W _r + C _W can be obtained.

Thereafter, the controller 10 reads the steering angle θ from the output signal of the steering angle sensor 7 (step S1).
45).

Further, the compensation coefficient K _th is calculated from the read steering angle θ (step S146). The calculation of the compensation coefficient K _th can be obtained by making a correction map for the steering angle θ as shown in the figure through experiments or the like.

The compensation coefficients K _V, K _W, obtained in this way
The deceleration coefficient K _AP is calculated by multiplying K _th by the deceleration coefficient K _AP 0 under the reference condition (step S1).
47).

FIG. 4 is a flowchart showing the brake pressure compensation calculation executed in step S9 according to the present invention. In FIG. 4, step S21 is replaced with step S90 in contrast to the conventional flowchart shown in FIG. The only difference is the change.

That is, the target deceleration Y calculated in step S6 (in this case, Y is a small value Y <Y ₀ ,
It is deceleration, not acceleration. ) Is calculated (step S90), but here, the target deceleration Y is not multiplied by the constant M as in the conventional case, but instead, the deceleration coefficient K obtained in step S14 as described above is used. _{Use AP} .

That is, since the deceleration coefficient K _AP is represented by the actual deceleration / brake pressure as shown in FIG. 8, the manipulated variable (input voltage) E _ref for the pressure control valve 5 is set.
For this, 1 / K _AP , which is the reciprocal of this deceleration coefficient K _AP , is used, and this can be multiplied by the target deceleration Y.

Others are the same as in the case of FIG. 7, and it is necessary not only to calculate the target deceleration Y as the operation amount as in step S90 but also to perform the brake pressure compensation based on the relationship with the actual deceleration. Therefore, the difference ΔY = Y−Y _P between the target deceleration Y and the actual deceleration Y _P obtained from the vehicle speed V (or detected by the acceleration sensor) is obtained (step S22). Then, a value N · ΔY for adjusting the control characteristic is obtained by multiplying the deceleration difference value ΔY by a constant N.

Then, the manipulated variable (voltage) E _ref calculated in step S21 is added to the adjustment value N · ΔY of the control characteristic to obtain a control value E _ref ′ = E _ref + N · ΔY (step S24).

In this way, the optimum automatic braking control for the target deceleration Y is performed, but the present invention is not limited to the acceleration / deceleration compensation routine shown in FIG. Optimal automatic brake control can be realized for any target deceleration Y manually set by the volume or the like.

[0049]

As described above, according to the vehicle speed control apparatus of the present invention, the deceleration coefficient indicating the ratio of the vehicle deceleration to the brake pressure is obtained from the vehicle speed, the front and rear axle weight, and the steering angle. , A target brake pressure is calculated from the reciprocal of the deceleration coefficient and the calculated or set target deceleration, and the target brake pressure is corrected according to the difference between the target deceleration and the actual deceleration obtained from the vehicle speed. Since it is configured to control the target deceleration by adjusting the brake pressure with the brake pressure, it is possible to bring the acceleration / deceleration of the own vehicle close to the target acceleration / deceleration quickly, and to change the characteristics of the controlled object automatically. It is possible to maintain a safer constant-speed driving and distance between vehicles.

Particularly, in a trailer or the like, the front wheels are braked earlier than the rear wheels due to a delay in air pressure control and the like, and as a result, a jack knife phenomenon occurs. At this time, the heavier the load, the slower the trailer deceleration. Becomes smaller, and the jackknife phenomenon gets severer. Since the present invention prevents the trailer from decreasing its deceleration, the jack knife phenomenon can be made slight. Further, by installing the acceleration sensor on the tractor, the trailer, or the like, the deceleration delay of the trailer can be improved. Furthermore, the jack knife phenomenon can be further improved by previously providing a time difference between the brake pressure adjustments for the rear wheels and the front wheels.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle speed control device according to the present invention.

FIG. 2 is an overall flowchart of a control program executed by a controller used in the vehicle speed control device according to the present invention.

FIG. 3 is a specific flowchart of the calculation of a deceleration coefficient (step S14) in the flowchart of FIG.

FIG. 4 is a specific flowchart of the calculation (step S9) of the target brake operation amount in the flowchart of FIG.

FIG. 5 is a block diagram showing a configuration of a vehicle speed control device according to a conventional example.

FIG. 6 is an overall flowchart of a control program executed by a controller used in a vehicle speed control device according to a conventional example.

FIG. 7 is a specific flowchart of the calculation (step S9) of the target brake operation amount in the flowchart of FIG.

FIG. 8 is a characteristic graph showing the relationship among deceleration, brake pressure, and various factors of the vehicle.

[Explanation of symbols]

 1 radar device 2 vehicle speed sensor 4 throttle valve actuator 5 pressure control valve 6 front and rear wheel load sensor 7 steering angle sensor 10 controller In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A vehicle speed control device for automatic deceleration control based on a calculated or set target deceleration, a vehicle speed detection means, a means for detecting the front and rear axle weight of the vehicle, a steering angle detection means, and a brake. A pressure adjusting means, a deceleration coefficient indicating a ratio of the vehicle deceleration and the brake pressure are obtained from the vehicle speed, the front and rear axle weights, and the steering angle, and a target brake pressure is obtained from the reciprocal of the deceleration coefficient and the target deceleration. A means for correcting the target brake pressure according to a difference between the target deceleration and an actual deceleration obtained from the vehicle speed to control the brake pressure adjusting means to thereby control the target deceleration. A vehicle speed control device characterized by being provided. 2. The vehicle speed control device according to claim 1, further comprising means for detecting an inter-vehicle distance between the front vehicle and the own vehicle, wherein the control means detects the inter-vehicle distance from the front vehicle and the own vehicle. The relative speed is calculated, the safe inter-vehicle distance is calculated from the vehicle speed and the relative speed, and the required acceleration is calculated from the relative speed,
A vehicle speed control device, wherein a target deceleration is calculated from the acceleration, the safe inter-vehicle distance, and the inter-vehicle distance.