JP3067584B2 - Auto cruise control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic cruise control method, which is devised so that an automatic cruise can be run on an uphill road at a speed that minimizes fuel consumption according to the gradient of the uphill road.

[0002]

2. Description of the Related Art There is an auto cruise device as a device for reducing fatigue of a driver of a vehicle. For vehicles equipped with an auto cruise device, if the desired vehicle speed is reached by operating the accelerator pedal while the auto cruise main switch is turned on, pressing the set switch will cause the control unit to change the vehicle speed at that time to the target vehicle speed. After that, the vehicle automatically runs at the target vehicle speed without depressing the accelerator pedal.

When the resume switch (which also uses the function of an acceleration switch) is pressed during auto cruise traveling (in the set state), the vehicle is accelerated, and when the finger is released, the vehicle is set at the accelerated vehicle speed. When the set switch (which also uses the function of the coast switch) is pressed, the speed is reduced, and when the finger is released, the vehicle is set at the reduced vehicle speed.
On the other hand, the set state is released by depressing an accelerator pedal or a foot brake pedal. When the set is released, engine control is performed according to the amount of depression of the accelerator pedal. When the resume switch is turned on after the setting is released, the vehicle speed is controlled to the vehicle speed of the previous set state, and the vehicle returns to the auto cruise running state.

During auto cruise traveling, engine control is mainly performed to maintain the vehicle speed at the target vehicle speed. Further, as exemplified in Japanese Utility Model Laid-Open Publication No. 4-65624, even when the vehicle speed increases to a target vehicle speed or more even when the minimum fuel supply amount is reached due to downhill traveling or the like during auto cruise traveling. Controls the automatic operation of auxiliary brakes (exhaust brakes, etc.) to maintain the target vehicle speed. Further, as disclosed in Japanese Patent Application Laid-Open No. 61-113523, the braking force of the retarder during deceleration is controlled by an auto cruise control device to achieve a wide range of auto cruise travel.

Here, the procedure of the conventional auto cruise control will be summarized with reference to a flowchart shown in FIG. When the set switch is pressed in step 1 of FIG. 7, the current vehicle speed is set as the target vehicle speed in step 2, and in step 3, engine control and auxiliary brake control are performed so that the vehicle speed becomes the target vehicle speed.

If the set switch has not been depressed in step 1, it is determined in step 4 whether or not the vehicle is in auto cruise traveling. If it is determined that the vehicle is in auto cruising, the process proceeds to step 3 in which the target vehicle speed is set. Control so that If it is determined in step 4 that the auto cruise is not running, that is, if it is determined that the accelerator pedal or brake pedal has been depressed and the set has been released, step 5 corresponds to the amount of depression of the accelerator pedal. Engine control is performed.

[0007]

In the prior art, the vehicle speed is controlled so that the vehicle speed becomes the target vehicle speed (constant vehicle speed) during auto cruise traveling. Therefore, when the vehicle enters an uphill road from a flat road, the vehicle speed is adjusted to the target vehicle speed. However, there is a problem in that the fuel consumption increases due to an increase in the amount of fuel in an attempt to maintain the fuel consumption.

The present invention has been made in view of the above-mentioned prior art, and has as its object to provide an automatic cruise control method capable of performing an automatic cruise on an uphill road at a vehicle speed that minimizes fuel consumption.

Incidentally, Japanese Utility Model Laid-Open Publication No. 4-39125 discloses that
There is disclosed a constant-speed traveling device for a vehicle in which the gradient of a road surface is detected by a gradient detecting means, and the target vehicle speed is decreased when the vehicle is going uphill, and the target vehicle speed is increased when the vehicle is going downhill. Not.

[0010]

In order to solve the above-mentioned problems, the present invention sets a vehicle speed when the set switch is turned on as a target vehicle speed when the set switch is turned on while the auto cruise main switch is turned on. In the automatic cruise control method for storing and automatically cruising so that the vehicle speed is equal to the target vehicle speed, a gradient of a road ahead of the vehicle is detected by a gradient measuring unit, and the vehicle is climbed forward from a value of the detected gradient. When it is determined that there is a road, a minimum fuel consumption vehicle speed capable of traveling on an ascending road with the detected gradient with minimum fuel consumption between the current target vehicle speed and a vehicle speed lower by a fixed vehicle speed than the current target vehicle speed is determined. And resetting the value of the target vehicle speed to the value of the minimum fuel-efficient vehicle speed.

Further, according to the present invention, the gradient measuring means compares the traveling road image obtained by the camera and the traveling road model image on their side edge lines, and displays the distance between the two images in the vertical direction on the screen. It is characterized in that a deviation is detected, and a gradient degree on the traveling road is measured based on the deviation between the two images.

Further, the present invention is characterized in that the gradient measuring means is a navigation device.

[0013]

According to the present invention, before entering the uphill road, the gradient of the uphill road is detected, the minimum fuel-efficient vehicle speed at which the vehicle can travel on the uphill road of this gradient with minimum fuel efficiency is obtained, and the value of the target vehicle speed is minimized. Auto cruise on an uphill road with the fuel efficiency reduced to the value of the vehicle speed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

<Overall Configuration and Outline of Operation of Control System> First, the overall configuration and outline of operation of the control system of the auto-cruise system of the present embodiment will be described with reference to FIG. As shown in FIG. 1, an auto cruise control unit 1 in a vehicle such as a truck includes an auto cruise main switch 2, a set switch 3 for setting an auto cruise vehicle speed and decreasing the auto cruise vehicle speed. ,
A resume switch 4, an auto cruise release switch 5, an accelerator switch 6, and a stop lamp switch 7 for returning from the time of auto cruise temporary release and increasing the auto cruise vehicle speed are connected. When the respective switches are closed, the respective switch signals are input to the control unit 1 and the vehicle speed signal is input from the vehicle speed sensor 8. The auto cruise release switch 5 is closed by a manual switch of an exhaust brake, an operation signal of a clutch and a foot brake, and a neutral signal of a transmission.

The control unit 1 turns on the cruise lamp 9 during auto cruise driving, and sends a signal to an electronic governor 10 of a diesel engine (not shown) to increase or decrease the amount of fuel supplied to the diesel engine, thereby automatically controlling the vehicle speed. Control is performed to maintain the target vehicle speed. Further, if the vehicle speed exceeds the target vehicle speed during the operation of the engine brake, the operation of the auxiliary brake 11 is controlled so as to approach the target vehicle speed.

The auxiliary brake 11 is a first-stage exhaust brake 1
2, second-stage exhaust brake 13, first-stage compression-release engine brake auxiliary device 14, second-stage compression-release engine brake auxiliary device 15, first-stage retarder 16, second-stage retarder 17, third stage It comprises a retarder 18 and a fourth stage retarder 19. The exhaust brakes 12, 13 increase and decrease the braking force according to the strength of the throttle of the exhaust pipe. The compression-release engine brake assist devices 14 and 15 increase or decrease the braking force by switching the number of cylinders that open a third valve provided in an engine cylinder from a compression stroke to an expansion stroke, for example. Retarder 16,
Numerals 17, 18, and 19 are for increasing or decreasing the braking force by adjusting the flow rate of the retarder, for example, by changing the blade angle of the stator in the fluid type retarder. It goes without saying that the retarder is not necessarily limited to the fluid type.

As the deviation between the vehicle speed and the target vehicle speed of the auto cruise increases, and / or as the acceleration of the vehicle increases, the auxiliary brake 11, for example, has a first-stage exhaust brake 12, a second-stage exhaust brake 13, The first stage compression pressure release type engine brake auxiliary device 14, the second stage compression pressure release type engine brake auxiliary device 15, the first stage retarder 16, the second stage retarder 17, the third stage retarder 18, and the fourth stage retarder 19 are provided. Each of them works sequentially,
The auxiliary braking force is gradually increased. Conversely, as the deviation between the vehicle speed and the auto cruise target vehicle speed decreases, the respective operations are released in the reverse order to the above, and control is performed so that the auxiliary braking force is gradually reduced. The order of operation and release of each unit in the auxiliary brake 11 can be changed as appropriate, and the type and number of each unit in the auxiliary brake 11 are not limited to the above and can be changed at any time. Needless to say.

Further, the gradient degree φ detected by the gradient degree measuring device 20 is input to the control unit 1 for auto cruise. Although the details will be described later, the gradient degree measuring device 2
0 denotes a stereo camera 21 and an image processing controller 23
And detects the gradient of the road ahead of the vehicle using an image processing technique.

While the vehicle is running, the main switch 2
If the set switch 3 is closed when the vehicle reaches a desired speed after the vehicle is closed, the vehicle speed at that time is set and stored as an auto cruise target vehicle speed, and auto cruise traveling is started. As will be described later, the target vehicle speed is reset to a lower vehicle speed depending on the relationship between the gradient of the road ahead of the vehicle and the target vehicle speed at that time. When the auto cruise starts, the output of the diesel engine is adjusted by the control of the electronic governor 10 by the control unit 1, and the vehicle speed is maintained at the auto cruise target vehicle speed. When the vehicle speed is increased due to downhill traveling or the like, the engine becomes idle, and even if the engine brake is actuated by fuel cut to the engine, if the vehicle still increases in speed, the control unit 1 controls the auxiliary brake 11 to operate. The vehicle is automatically controlled to operate in the above order, and the vehicle speed is maintained at the target vehicle speed.

<Operation for Resetting Target Vehicle Speed> The control operation for resetting the target vehicle speed by the auto cruise control unit 1 will now be described with reference to FIG. 2 which is a flowchart. In FIG. 2, the operations in steps 1 to 5 are the same as those in the conventional technique shown in FIG.
The operations of steps 11 to 14 are operations added according to the present invention.

The road ahead of the vehicle is straight,
When the gradient measuring device 20 has not detected the gradient,
The vehicle speed when the set switch 3 is turned on is set and stored as the target vehicle speed (steps 1 and 2).

The gradient degree φ [%] is measured by the gradient degree measuring device 20.
Is measured (step 11), and the measured gradient degree φ
[%] Is input to the control unit 1 for auto cruise. When the gradient degree φ is a positive value, the control unit 1 determines that there is an uphill road ahead (step 12).

When it is determined that there is an uphill road ahead,
The control unit 1 switches between the target vehicle speed and a vehicle speed lower than the target vehicle speed by a constant vehicle speed (10 km / h in this example).
The minimum fuel-efficient vehicle speed at which the vehicle can travel on the uphill road with the detected gradient φ with the minimum fuel efficiency is calculated (step 13). Details of the calculation method of the minimum fuel consumption vehicle speed will be described later.

After calculating the minimum fuel consumption vehicle speed, the value of the target vehicle speed is changed to the value of the minimum fuel consumption vehicle speed (step 14). When the value of the target vehicle speed is reset to the minimum fuel-efficient vehicle speed of a smaller value, control is performed so that the vehicle speed becomes the newly set target vehicle speed (= minimum fuel-efficient vehicle speed) (step 3). As a result, the vehicle speed is reduced (down to 10 km / h at maximum) as compared to running on a flat road, but the vehicle can be automatically cruised on an uphill road with the minimum fuel-efficient vehicle speed, and the fuel efficiency is improved.

<Method of Calculating Minimum Fuel Consumption Vehicle Speed>
A method for calculating the minimum fuel consumption vehicle speed by the control unit 1 will be described.

The control unit 1 stores, as data, characteristic curves indicating running performance and equal fuel consumption characteristics as shown in FIG. The following equations (1) to (4) are related between the parameters in FIG. However, A is the fuel consumption g / h, a _m fuel consumption rate [g / ps · h, T e is engine torque kgf · m, R is the tire dynamic radius [m], F is the driving force kgf, i _f differential gear ratio, i _t
Is the transmission gear ratio, η is the power transmission efficiency (0.931 at 7th speed), V is the vehicle speed km / h, and N is the engine speed rpm.

[0028]

(Equation 1)

In FIG. 3, the solid line represents the engine speed N,
Dashed line gradient of φ 2%, 1%, the running resistance f when 0%, dotted consumption rate a _m fuel 154,155,16
The equal fuel consumption curve at 0, 165, 170 is shown, and the thick solid line shows the driving force F.

For example, if the vehicle is traveling on a flat road at an automatic cruise speed of 80 km / h, the engine is in the state of point B. In the state of the point B, a _m = 165 [g / ps · h, F =
Since 300 kgf and V = 80 km / h, the fuel consumption A g / h is 15760.8 g / h from the equation (4).

If the vehicle speed is kept at 80 km / h and the gradient φ is 2
% (That is, when the target vehicle speed does not change even if there is a gradient. This corresponds to the prior art), the control unit 1 increases the fuel injection amount in order to maintain the vehicle speed, and the engine The state at point C is obtained. In the state of the point C, a _m = 155 [g / ps · h, F = 6
Since 80 kgf and V = 80 km / h, the fuel consumption A
g / h is increased to 33559.4 g / h from equation (4).

Therefore, in the present invention, for example, when the gradient φ is 2
[%], It is possible to climb a 2% slope and to increase the speed by 10 k from the current vehicle speed (for example, 80 km) and the current vehicle speed.
A point D of the vehicle speed (71 km / h) at which the fuel consumption rate becomes minimum between the vehicle speed (m / h) and the decelerated vehicle speed (70 km / h) is obtained from the characteristics in FIG. In the state of the point D, the vehicle speed V is 71 km / h,
Since a _m = 154 [g / ps · h and F = 680 kgf, the fuel consumption A g / h is calculated from the equation (4) as 27851.1.
g / h, indicating that the fuel consumption A is reduced as compared to climbing a 2% slope with the vehicle speed kept at 80 km / h.

Therefore, the target vehicle speed when traveling on a flat road is 80
When the control unit 1 detects that the gradient of the road ahead is 2 [%] when the vehicle speed is km / h, the control unit 1 obtains a vehicle speed 71 km / h at which the minimum fuel consumption is achieved by using the characteristic curve shown in FIG. Reset the target vehicle speed to 71 km / h.

It is to be noted that, without using the characteristics shown in FIG. 3, with respect to data obtained by combining each vehicle speed and each gradient, the gradient is climbed with minimum fuel consumption without decelerating the vehicle speed beyond a certain vehicle speed (eg, 10 km / h or more). A possible vehicle speed may be stored in advance in correspondence with the memory, and the vehicle speed to be newly set may be read from such a data table memory.

<Details of Configuration and Operation of Gradient Measuring Device> The configuration and operation of the gradient measuring device 20 will now be described in detail. This gradient degree measuring device 20 utilizes the technique shown in “Runway gradient measuring method” of Japanese Patent Application No. 6-340562 filed earlier.

As shown in FIG.
Has two CCD cameras arranged on the upper and lower sides of the front of the vehicle toward the front of the vehicle, respectively. The terminal 22 of each CCD camera is connected to the image processing controller 23 and the clock terminal 24 of the stereo camera 21 Are connected to the image processing controller 23.

In the image processing controller 23, as shown in FIG. 4, a front straight flat road model image 3 corresponding to the mounting position of each CCD camera is displayed on the screen 30 of each CCD camera.
1, that is, since the running road is a straight flat road, an image is drawn which linearly converges substantially to the center corresponding to the distance from the front of the vehicle, and an actual image 32 of the front running road captured by the CCD camera. In this case, if the road surface is a flat road, the length upward from the lower end of the screen 30 represents the actual horizontal distance from the vehicle to the front.

On the screen 30, four suitable reference points p1, p on the left end white line 33 of the actual road image 32 are displayed.
2, p3, p4 and these respective reference points p1, p2, p3
The vertical lengths of points q1, q2, q3, and q4 where the vertical lines passing through p4 intersect with the left end white line 34 of the model image 31, which is a straight line inclined upward and to the right, are represented by h, respectively.
1, h2, h3, h4, and each point q1, q2, q
3 and q4 and the bottom length of the screen 30
Let l2, l3, l4.

On the other hand, as shown in FIG.
Vertical image 35 inverted and drawn on 0 and its real image 3
V: vertical length of the entire screen 30 f: focal length of the lens 37 in the CCD camera h: vertical length of the vertical image 35 L: actual horizontal distance from the lens 37 to the real image 36 t: Assuming that l is the height at which the lens 37 is attached to the road surface, l is the vertical length from the upper end of the screen 30 to the vertical image 35, and H is the vertical distance of the real image 36, the following equation is established. H = L / f × h = t / (V / 2-1) × h (11)

Therefore, by using equation (11),
The upper and lower lengths h1, h2, h3, h on the screen 30
4 can be converted into actual vertical distances H1, H2, H3, and H4, respectively. In addition, from the front of the vehicle equipped with the stereo camera 21, each reference point p1,
Actual horizontal distances L1, L2, L3 to respective points on the actual left end white line corresponding to p2, p3, p4, respectively.
L4 is a vertical length l1, l2, l3, l4 on the screen 30.
, Or by a distance measuring sensor based on a stereo image of the stereo camera 21, or can be measured in advance from a straight road model.

Next, as shown in FIG.
On a plane, a point P1 (L1, H1) and a point P2 (L
2, H2), point P3 (L3, H3), point P4 (L4, H
4) are plotted, and points P1, P2, P3, P
4 is drawn by the least-squares method, and if the approximate straight line S becomes H = α (L−β) (12), the gradient angle θ of the traveling road can be approximately obtained by the following equation. it can. tan θ = α (13)

That is, if θ> 0, the traveling path is at points P1 to P1.
At a point corresponding to the point P4, it is determined that the slope angle θ is an uphill slope. If θ <0, the traveling road is determined to be a downhill slope of the gradient angle θ at points corresponding to the points P1 to P4. The traveling road can be determined to be a substantially flat road at a point corresponding to the points P1 to P4. Note that the image processing controller 23 converts the gradient angle θ into a gradient degree [%] and outputs it.

If H = 0 in the equation (12), L = β (14) That is, it can be estimated that the gradient of the traveling road starts from a distance of approximately β ahead of the vehicle.

From the above, at the point on the traveling road corresponding to the points P1 to P4, it is possible to easily estimate whether the traveling road has an upward or downward gradient or whether the traveling road is a substantially flat road. In addition, when any one of the upper and lower gradients appears on the traveling road, the gradient can be calculated quantitatively, so that the situation of the traveling road ahead can be accurately grasped.

Further, since these measurements can be performed instantaneously, the driving of the vehicle on the traveling path can be facilitated, and the above-mentioned measurements are performed by the two upper and lower CCD cameras on the front of the vehicle. Therefore, there is an advantage that the accuracy can be easily improved.

In the above example, four reference points are set on the left end line of the actual road image on the screen of the CCD camera, and
Although the detection of the vertical gradient of the traveling path and the measurement of the gradient are performed, more reference points are selected. For example, one section is set for every four consecutive reference points. If the gradient is measured, each continuous gradient change can be instantaneously measured even on a traveling road that repeatedly goes up and down.

In each of the above examples, each reference point is set on the left end line of the actual road image on the screen of the CCD camera, but each reference point is set on the left end line of the straight flat road model image. Take the points, detect the vertical length from each reference point to the left end line of the actual road image,
By performing the same processing as in the above example, it is possible to achieve the same operation and effect as in the above example, or alternatively, using the right end line of the traveling path instead of each of the left end lines. Can provide the same function and effect.

Further, a single CCD camera may be used, or the CCD camera may be disposed on the left and right sides of the front of the vehicle to perform the same treatment as in each of the above embodiments. It is needless to say that it is good to improve the measurement accuracy by installing as high as possible on the front of the vehicle.

In the above embodiment, the gradient measuring device for obtaining the gradient φ using the image processing technique is used. However, if the gradient is input as information in the information of the navigation system, this navigation system is used. The inclination degree φ may be obtained from a navigation device that uses.

[0050]

According to the present invention, as described above in detail with the embodiment, the gradient of the uphill road is detected before the vehicle enters the uphill road, and the vehicle travels on the uphill road with the detected gradient with minimum fuel consumption. Since the minimum fuel-efficient vehicle speed is determined and the target vehicle speed value is reduced to the minimum fuel-efficient vehicle speed value, it is possible to auto-cruise on an uphill road with good fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a characteristic curve showing running performance and equal fuel consumption characteristics.

FIG. 4 is an image diagram showing an image drawn by a gradient measuring device used in the embodiment.

FIG. 5 is an explanatory diagram showing a measuring method in the gradient measuring device.

FIG. 6 is an explanatory diagram showing a measuring method in the gradient measuring device.

FIG. 7 is a flowchart showing a conventional auto cruise control procedure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control unit 2 Auto cruise main switch 3 Set switch 4 Resume switch 5 Auto cruise release switch 7 Stop lamp switch 8 Vehicle speed sensor 10 Electronic governor 11 Auxiliary brake 20 Gradient measuring device 21 Stereo camera 23 Image processing controller 30 Camera screen 31 Straight line Flat road model image 32 Real image

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60K 31/00 F02D 29/02 301 F02D 41/14 G05D 13/62

Claims (3)

(57) [Claims] When a set switch is turned on while the auto cruise main switch is turned on, a vehicle speed at the time of turning on the set switch is set and stored as a target vehicle speed, and an automatic operation is performed so that the vehicle speed becomes the target vehicle speed. In the auto cruise control method for cruising, the gradient of the road ahead of the vehicle is detected by the gradient measuring means, and when it is determined that there is an uphill road based on the detected value of the gradient, the current target vehicle speed and the current target vehicle speed are determined. From the current target vehicle speed to a vehicle speed lower by a certain vehicle speed, a minimum fuel consumption vehicle speed capable of traveling on an ascending road with the detected gradient with minimum fuel consumption is obtained.
An automatic cruise control method characterized by resetting a target vehicle speed value to a minimum fuel-efficient vehicle speed value. 2. The image forming apparatus according to claim 1, wherein the gradient measuring unit compares the traveling road image and the traveling road model image obtained by the camera on their side edge lines, and displays the two images in a vertical direction on a screen. An automatic cruise control method, comprising detecting a deviation between the two images and measuring a gradient on the traveling road based on the deviation between the two images. 3. The automatic cruise control method according to claim 1, wherein said gradient measuring means is a navigation device.