JPH11227494A - Vehicle speed control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the distance between two cars and the constant speed by common vehicle speed control without requiring the change of feedback elements by computing vehicle speed for controlling the distance between cars based on the distance against the car in front and the own car speed, and deciding a target vehicle speed from the minimum value selection of the vehicle speed for controlling the distance between cars and the set vehicle speed for controlling constant speed. SOLUTION: A correction vehicle speed deciding function 14 obtains a correction vehicle speed based on, for example, three correction vehicle speed maps (a)-(c) having a relative speed and a distance between cars deviation as parameters. A computation function 15 sums up the correction vehicle speed and the own car speed and obtains the vehicle speed for controlling the distance between cars required for keeping a target distance between cars according to the distance condition between the car in front and the own car. Further, a minimum value selection function 16 regulates so that a vehicle speed for controlling the distance between cars exceeding the set vehicle speed is not set as the target vehicle speed, from the minimum value selection of the vehicle speed for controlling the distance between cars and the set vehicle speed. Thus, by common vehicle speed control without requiring the change of feedback elements, both the constant speed and the distance between cars according to cruise vehicle speed can be controlled.

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 having a constant speed function for maintaining a vehicle speed at a set vehicle speed and a constant vehicle distance function for maintaining a vehicle distance of a preceding vehicle at a target vehicle distance.

[0002]

2. Description of the Related Art In order to reduce the burden of driving operation of a driver, an automobile is equipped with a vehicle speed control device called an auto cruise device. Recent vehicle speed control devices not only control the vehicle speed so as to be kept substantially constant at the set vehicle speed, but also use an inter-vehicle distance sensor such as a laser radar unit to communicate with the preceding vehicle when there is a preceding vehicle. 2. Description of the Related Art Vehicle speed is controlled to maintain a safe inter-vehicle distance (target inter-vehicle distance).

[0003] A vehicle speed control device using both the constant speed control function and the inter-vehicle distance control function depends on the presence or absence of a preceding vehicle. At the time, the mode is switched to the inter-vehicle distance control function. Specifically, the engine output is adjusted by feedback control of the vehicle speed by the constant speed control unit during independent driving using the constant speed control unit and the headway control unit to maintain the set vehicle speed. Switching to a control unit is performed to adjust the engine output by feedback control of the inter-vehicle distance by the inter-vehicle control and maintain the target inter-vehicle distance.

However, when switching between constant speed control and inter-vehicle distance control, a large shock is likely to occur since the feedback element is greatly changed with the switching between vehicle speed feedback control and inter-vehicle distance feedback control.

Therefore, Japanese Patent Application Laid-Open No. Hei 8-216728 discloses that
At the time of switching between constant speed control and inter-vehicle control, it has been proposed to gradually reduce the gain of at least one of the controls to gradually shift the control.

[0006]

However, this technique is intended only to reduce the shock at the time of switching between constant speed control and inter-vehicle control, and cannot suppress sudden acceleration during inter-vehicle control. There is. That is, at the time of inter-vehicle control, when the preceding vehicle suddenly accelerates, the own vehicle also suddenly accelerates, and there is a problem that such a rapid acceleration may cause a feeling deterioration factor for the driver in the easy drive state.

For this reason, it is conceivable to incorporate a control process for suppressing sudden acceleration during inter-vehicle control. However, since control process completely different from the above-described control gain adjustment is required, the control process becomes complicated. There is a problem.

In the conventional vehicle speed control in which the feedback element differs between the constant speed control and the inter-vehicle control, if a problem occurs in the feeling or the like, a separate control process is often required for each situation in which the problem occurs. However, the device becomes complicated.

[0009] Further, if it is attempted to simplify the control process for improving the feeling by suppressing the output fluctuation by the control process in the engine output control unit which is a common output unit for the constant speed control and the headway control, Cannot respond to changes in vehicle load (road gradient, load capacity), and cannot be practical.

Therefore, there is a demand for a vehicle speed control device having a generally excellent constant speed / inter-vehicle control function. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to use a common vehicle speed control that does not need to change a feedback element, and to improve a wide range of vehicle speed by a simple control process. It is to provide a control device.

[0011]

According to a first aspect of the present invention, there is provided a vehicle speed control apparatus for calculating a vehicle speed for vehicle-to-vehicle control based on a vehicle-to-vehicle distance to a preceding vehicle and a vehicle speed. , And the target vehicle speed is determined from the minimum value selection of the vehicle speed for the headway control and the set vehicle speed for the constant speed control,
The inter-vehicle control and the constant speed control can be performed according to the set vehicle speed by the common vehicle speed control without changing the feedback element, and the output control value of both the constant speed control and the inter-vehicle control by the common vehicle speed control is controlled. In order to prevent sudden change, the amount of change per hour of the target vehicle speed is limited to a predetermined value or less by acceleration limiting means, thereby realizing constant speed / inter-vehicle control capable of reducing a shock when the output control value changes suddenly. It is in.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. In FIG. 1, reference numeral 1 denotes a vehicle equipped with, for example, a diesel engine 2 for driving, and reference numeral 3 denotes a vehicle speed control device called an auto cruise device mounted on the vehicle 1.

The vehicle speed control device 3 includes a diesel engine 2
Cruise control unit 4 (comprising, for example, a microcomputer, hereinafter simply referred to as the control unit 4) connected to the governor control unit 2a. This control unit 4 includes:
For example, an inter-vehicle distance sensor 5, a vehicle speed sensor 6, and a set vehicle speed input unit 7 configured by a laser radar unit are connected, and the inter-vehicle distance to the preceding vehicle 20 is input from the inter-vehicle distance sensor 5, and the own vehicle is input from the vehicle speed sensor 6. , And a set vehicle speed (cools vehicle speed) at which auto cruise is to be performed is input from the set vehicle speed input unit 7.

The control unit 4 uses one common vehicle speed control to perform constant speed control (a function of maintaining the vehicle speed at a constant speed).
And a function to perform both the inter-vehicle control (the function of keeping the inter-vehicle distance with the preceding vehicle at the target inter-vehicle distance). A block diagram of this function is shown in FIG.

To explain these functions, the control unit 4 has a relative speed calculating function 10 for calculating the relative speed with respect to the preceding vehicle 20 from the amount of change in the inter-vehicle distance per unit time, as shown in FIG. A target inter-vehicle distance setting function 11 for setting the target inter-vehicle distance from the vehicle speed, and a calculation function 12 for calculating a deviation between the target inter-vehicle distance and the inter-vehicle distance (= detected inter-vehicle distance-target inter-vehicle distance) are formed.

The control unit 4 is provided with a target vehicle speed determining function 13, which determines the target vehicle speed using the relative speed, the inter-vehicle distance deviation and the set vehicle speed.

That is, the target vehicle speed determining function 13 is shown in FIG.
As shown in (b), a corrected vehicle speed determining function 14 for obtaining a corrected vehicle speed corresponding to the relative speed and the inter-vehicle distance deviation, and an arithmetic function 15 for obtaining the inter-vehicle control vehicle speed from the sum of the obtained corrected vehicle speed and the own vehicle speed (both are shown). A minimum value selection function 16 (target vehicle speed selection) which selects a minimum value between the obtained vehicle distance control vehicle speed and the set vehicle speed set by the set vehicle speed input unit 7 to obtain a target vehicle speed. And a maximum value selecting function 17 for selecting a maximum value of a target vehicle speed and a preset minimum cruise vehicle speed (for example, 40 km / h) to obtain an effective target vehicle speed.

More specifically, the corrected vehicle speed determining function 14 sets three corrected vehicle speed maps a to c using the relative speed and the inter-vehicle distance deviation as parameters, for example, as shown in FIG.

Here, the respective corrected vehicle speed lines a to c are linearly displaced at different angles within a predetermined range where the vehicle distance deviation is 0, and outside the range, the corrected vehicle speed is regulated to a constant value. The corrected vehicle speed according to the inter-vehicle situation (relative speed, inter-vehicle distance deviation) between the preceding vehicle 20 and the host vehicle is determined from each of the corrected vehicle speed maps a to c. When the inter-vehicle distance deviation is large, a correction vehicle speed value that does not cause excessive acceleration / deceleration is selected by using a regulation that sets the correction vehicle speed to a constant value.

In accordance with the arithmetic processing (sum of the corrected vehicle speed and the own vehicle speed) performed by the arithmetic function 15, the inter-vehicle control necessary for maintaining the target inter-vehicle distance in accordance with the inter-vehicle condition between the preceding vehicle 20 and the own vehicle. Vehicle speed.

The minimum value selecting function 16 selects the minimum value between the inter-vehicle control vehicle speed and the set vehicle speed (cruise vehicle speed) so that the inter-vehicle control vehicle speed value exceeding the set vehicle speed is not set as the target vehicle speed. regulate.

The maximum value selection function 17 is a minimum value selection function 1
From the selection of the maximum values of the target vehicle speed and the minimum cruise vehicle speed from Step 6, the vehicle speed below the minimum cruise vehicle speed unsuitable for auto cruise is restricted from being set as the target vehicle speed.

Through such processing, a target vehicle speed can be obtained for each control cycle of the control unit 4 in consideration of the inter-vehicle situation between the preceding vehicle 20 and the host vehicle and the set vehicle speed. The target vehicle speed output from the target vehicle speed determination function 13 is
The amount of change per hour of the target vehicle speed is limited to a predetermined value or less by the acceleration limiting function 18a (corresponding to acceleration limiting means).

FIG. 2D shows the acceleration limiting function 18a.
An acceleration limit map that regulates the rate of change of the target vehicle speed during acceleration / deceleration as shown in FIG. The acceleration limit map includes a calculated value of the previous target vehicle speed (output value from the previous acceleration limiting mechanism 18a) output at each control cycle (for example, 50 ms) and a calculated value of the current target vehicle speed (from the current target vehicle speed determination function 13). 4 is a map in which the amount of change in the target vehicle speed is regulated in accordance with the difference between the target vehicle speed and the output value. Specifically, an acceleration limit value for suppressing a sudden change in acceleration / deceleration, for example, plus or minus 2 km / h (predetermined value) is defined as the limit value, and the displacement is linearly increased or decreased within a predetermined range of a difference operation value between zero. A diagram is used.

The acceleration limiting function 18a adds the acceleration limiting value obtained from this map to the previous target vehicle speed (the output value from the previous acceleration limiting function 18a) to obtain the target vehicle speed during acceleration / deceleration for each control cycle. That is, the target vehicle speed during acceleration / deceleration is set. Thus, for example, 2 km
While abrupt changes in the target vehicle speed exceeding / h are suppressed, linear acceleration / deceleration according to the target vehicle speed difference can be performed within the acceleration limit value.

The target vehicle speed after the acceleration limiting process output from the acceleration limiting function 18a is input to the calculating function 18b.
The deviation from the own vehicle speed is calculated. The output from the calculating function 18b, that is, the vehicle speed deviation is input to a common target rack position determining function 19 (a function for determining a rack position of a diesel engine, which corresponds to an output control unit of the present application) for determining a target rack position by PID control. And the same function 1
9, a target rack position (output control command value) based on a vehicle speed deviation between the target vehicle speed and the host vehicle speed common to both the constant speed control and the inter-vehicle distance control is obtained.

The target rack position is input to the governor control section 2a of the diesel engine 2, and a sudden change in vehicle speed is avoided while securing optimal acceleration / deceleration responsiveness by vehicle speed control common to constant speed control / inter-vehicle distance control. The auto cruise is realized.

That is, the operation of the vehicle speed control device will be described. Now, while the own vehicle 1 is traveling on the traveling lane following the preceding vehicle 20, for example, a cruise vehicle speed (set vehicle speed) higher than the preceding vehicle 20 is set to the set vehicle speed. Suppose that it is set by the input unit 7.

Then, the own vehicle 1 is controlled by the vehicle speed control device 3.
Does not depress the accelerator pedal and travels while maintaining an appropriate inter-vehicle distance with the preceding vehicle 20 that accelerates / decelerates. That is, the inter-vehicle distance is input to the control unit 4 from the inter-vehicle distance sensor 5 composed of a laser radar unit, and the own vehicle speed is input from the vehicle speed sensor 6.

Then, the relative speed calculation function 10 obtains a relative speed with respect to the preceding vehicle 20 from the inter-vehicle distance information, and outputs this to the target vehicle speed determination function 13. On the other hand, the target inter-vehicle distance setting function 11 determines an appropriate target inter-vehicle distance from the vehicle speed. The calculating function 12 calculates a deviation (= detected inter-vehicle distance−target inter-vehicle distance) between the target inter-vehicle distance and the inter-vehicle distance, and outputs this to the target vehicle speed determining function 13.

The target vehicle speed determining function 13 determines the preceding vehicle 20 and the own vehicle 1 based on the relative speed, the inter-vehicle distance deviation, and the set vehicle speed.
The target vehicle speed is determined based on the inter-vehicle situation (relative speed, inter-vehicle distance deviation).

That is, in the target vehicle speed determining function 13, the corrected vehicle speed is read from the three-dimensional corrected vehicle speed maps a to c shown in FIG.
For example, if the relative speed with respect to the preceding vehicle 20 is large and the inter-vehicle distance deviation is large, it is determined that the preceding vehicle 20 and the own vehicle 1 are gradually separated from each other, and a corrected vehicle speed for correcting the situation is read. .

Next, the sum of the corrected vehicle speed and the own vehicle speed is calculated by the calculating function 15 to calculate the inter-vehicle control vehicle speed for maintaining the target inter-vehicle distance. The vehicle speed for inter-vehicle control does not exceed the set vehicle speed (cruise vehicle speed: maximum control vehicle speed) by the subsequent selection by the minimum value selection function 16 and the maximum value selection function 17, and further, the minimum cruise vehicle speed (for example, 40 km / h: minimum) Control vehicle speed), and is set to an appropriate target vehicle speed.

Such a target vehicle speed is set every control cycle (for example, 50 ms) of the control unit 4. In the acceleration limiting function 18a, the acceleration control function map shown in FIG.
The previous calculated value of the target vehicle speed during acceleration / deceleration (acceleration limit function 18a
And the acceleration limit value corresponding to the difference between the current calculation value (the previous output of the target vehicle speed determination function 13) and the current calculation value (the current output of the target vehicle speed determination function 13).

Here, for example, if the preceding vehicle 20 is accelerating at a slow speed, the acceleration limit value per control cycle is a linear vehicle speed within a range of plus / minus 2 km / h that regulates sudden acceleration. Since the vehicle speed is set to the value, a vehicle speed value at which an appropriate acceleration performance according to the situation is exhibited is read.

Then, the sum of the vehicle speed and the own vehicle speed is calculated, and the target vehicle speed during acceleration is set according to the inter-vehicle condition with the preceding vehicle 20. The output of the calculating function 18b for calculating the deviation between the target vehicle speed during acceleration and the own vehicle speed is input to the target rack position determining function 19, and the target rack position (output control command value) is obtained.
Is obtained from the target rack position determining function 19, and the current output of the diesel engine 2 is increased through the governor control unit 2a.

As a result, the own vehicle 1 shortens the inter-vehicle distance with the preceding vehicle 20 and maintains the target inter-vehicle distance. The same applies when the preceding vehicle 20 decelerates at a slow speed.

On the other hand, during control of maintaining the following distance, the preceding vehicle 20
Accelerates rapidly. Then, the relative speed with respect to the preceding vehicle 20 rapidly increases, and the inter-vehicle distance deviation from the preceding vehicle 20 also rapidly increases.

As a result, the maximum corrected vehicle speed is read from the corrected vehicle speed map shown in FIG. 2 (c), and the vehicle speed for inter-vehicle control obtained by adding the corrected vehicle speed to the own vehicle speed is obtained, and becomes the target vehicle speed. At this time, if the inter-vehicle control vehicle speed exceeds the set vehicle speed, the set vehicle speed is determined as the target vehicle speed.
Does not run at a vehicle speed exceeding the set vehicle speed.

The target vehicle speed for each control cycle is determined by the preceding vehicle 20
Suddenly changes rapidly with rapid acceleration. However, the rate of change of the target vehicle speed is limited by the acceleration restriction map of the acceleration restriction function 18a so that the acceleration does not become excessive.

Specifically, in the acceleration limit map, for example, a target vehicle speed difference exceeding 2 km / h in a control cycle is defined by an acceleration limit value of 2 km / h regardless of any target vehicle speed difference. The target rack position of the diesel engine 2 is calculated in accordance with the deviation between the target vehicle speed during acceleration and the own vehicle speed obtained by the sum of the acceleration limit value and the own vehicle speed, and the current output of the diesel engine 2 is increased.

During acceleration of the preceding vehicle 20, a conversion value per control cycle (for example, 50 ms) of an acceleration limit value corresponding to the difference between the previous calculated value of the target vehicle speed during acceleration and the current target vehicle speed is calculated. The acceleration target vehicle speed is added to the acceleration target vehicle speed to obtain the current acceleration target vehicle speed.

Due to the acceleration limitation, the own vehicle speed gradually increases to the target vehicle speed even if the target vehicle speed changes greatly as shown in FIG. This allows
The vehicle 2 accelerates while suppressing the shock, shortens the inter-vehicle distance with the preceding vehicle 20 that has been rapidly accelerated, and maintains the target inter-vehicle distance.

When the preceding vehicle 20 is decelerated, the own vehicle 1 is decelerated in the same manner. On the other hand, during the control of maintaining the inter-vehicle distance, the preceding vehicle 20 traveling at a speed equal to or lower than the Cools vehicle speed (set vehicle speed) leaves the traveling lane of the own vehicle 1 due to a lane change or the like, that is, the own vehicle 1 independently changes the traveling lane. Suppose you are in a running situation.

At this time, the relative speed with respect to the preceding vehicle 20 is infinite, and the inter-vehicle distance deviation from the preceding vehicle 20 is also infinite. Here, since the relative speed and the upper / lower limit value of the inter-vehicle distance deviation in the corrected vehicle speed map of FIG. 2C are specified to be equal to or less than a predetermined value, the above-described inter-vehicle holding control when the preceding vehicle 20 suddenly changes is performed. By the same method, the maximum corrected vehicle speed corresponding to the value at which the relative speed is infinite and the inter-vehicle distance deviation is infinite is obtained. Then, the target vehicle speed is determined through the same processing (calculation, minimum value / maximum value selection) as the inter-vehicle holding control.

That is, the target vehicle speed is determined irrespective of the presence or absence of the preceding vehicle 20 by the process of calculating the inter-vehicle control vehicle speed based on the inter-vehicle distance of the preceding vehicle 20 and the own vehicle speed and the selection process. With 16, the target vehicle speed is set within the set vehicle speed.

Subsequently, according to the same processing as the control performed when the preceding vehicle 20 suddenly accelerates, the acceleration limit value of the acceleration limit map (2 km
/ h) is read.

As a result, the target rack position of the diesel engine 2 is calculated according to the deviation between the target vehicle speed during acceleration and the own vehicle speed obtained by the sum of the vehicle speed of the acceleration limit value and the own vehicle speed.

Until the Cools vehicle speed (set vehicle speed) is reached, a conversion value per control cycle (for example, 50 ms) of an acceleration limit value corresponding to the difference between the previous calculated value of the target vehicle speed during acceleration and the current target vehicle speed is calculated. Then, a process of adding the acceleration limit value to the acceleration target vehicle speed of the previous calculation value to obtain the current acceleration target vehicle speed is performed.

As a result, similar to the state shown in FIG.
Since the target vehicle speed of the own vehicle 1 gradually increases, the own vehicle 1 accelerates while suppressing the shock. Then, the vehicle speed reaches the cruise vehicle speed (set vehicle speed) and is maintained at the same cruise vehicle speed.

Thus, the process for calculating the inter-vehicle control vehicle speed based on the inter-vehicle distance to the preceding vehicle 20 and the own vehicle speed, and the process for setting the target vehicle speed in accordance with the process of selecting the minimum value between the inter-vehicle control vehicle speed and the cruise vehicle speed With the adoption of, it is possible to control both the constant speed control according to the cruise vehicle speed and the inter-vehicle control with the common vehicle speed control that does not require the change of the feedback element, and it is necessary to switch between the constant speed control and the inter-vehicle control Absent.

In addition, since the amount of change per hour of the target vehicle speed is limited to a predetermined value or less, a sudden change in the target rack position (output control value) is prevented in any of the constant speed control and the inter-vehicle control. Shock generation can be suppressed.
In addition, the acceleration limiting function 18a functions in a wide range such as when suddenly accelerating the preceding vehicle and when leaving the preceding vehicle to prevent the feeling from being deteriorated in a general-purpose manner. Feeling can be kept good.

Therefore, it is possible to realize a vehicle speed control device having an overall excellent constant speed / inter-vehicle control function. In particular, the calculation of the inter-vehicle control vehicle speed uses a corrected vehicle speed map in which the corrected vehicle speed is constant in a region where the inter-vehicle distance deviation is equal to or greater than a predetermined value. Control can be realized.

In addition, by performing the process of selecting the maximum value between the minimum cruise vehicle speed and the target vehicle speed, the range in which the constant speed / inter-vehicle distance holding control is performed is small, and the target rack position (output control value) is accordingly reduced. Since the change is small, there is an advantage that the shock accompanying the change in the target rack position is small.

In the embodiment, a car equipped with a diesel engine has been described as an example. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to a car equipped with a gasoline engine.

[0056]

As described above, according to the first aspect of the present invention, the common vehicle speed control that does not require a change in the feedback element is used for both the constant speed control according to the set vehicle speed and the headway control. Can be controlled. In addition, since the amount of change per hour of the target vehicle speed is limited to a predetermined value or less, in both the constant speed control and the inter-vehicle control, a sudden change in the output control value can be suppressed, and the occurrence of a shock accompanying the sudden change can be suppressed. The feeling under various conditions can be kept good by simple control processing. Therefore, it is possible to provide a vehicle speed control device having an overall excellent constant speed / inter-vehicle control function.

[Brief description of the drawings]

FIG. 1 is a diagram showing a vehicle speed control device according to an embodiment of the present invention, together with a vehicle equipped with the device.

FIG. 2 is a view for explaining each function of a control unit of the apparatus.

FIG. 3 is a diagram for explaining an acceleration situation until the vehicle speed reaches a target vehicle speed when the preceding vehicle changes suddenly.

[Explanation of symbols]

3: Vehicle speed control device 5: Inter-vehicle distance sensor 6: Vehicle speed sensor 7: Set vehicle speed input section 14, 15 ... Corrected vehicle speed determination function, calculation function (vehicle speed control vehicle speed calculation means) 16 ... Minimum value selection function (target vehicle speed selection means) 18a: Acceleration restriction function (acceleration restriction means) 19: Target rack position determination function (output control unit)

Claims (1)

[Claims] A constant speed control function for maintaining a vehicle speed at a set vehicle speed;
A vehicle speed control device having an inter-vehicle control function for maintaining an inter-vehicle distance with a preceding vehicle at a target inter-vehicle distance, comprising: an inter-vehicle control vehicle speed calculating means for calculating an inter-vehicle control vehicle speed based on the inter-vehicle distance with the preceding vehicle and the own vehicle speed. Target vehicle speed selecting means for determining a target vehicle speed by selecting a minimum value between the inter-vehicle control vehicle speed and a set vehicle speed for constant speed control; and an acceleration limit for restricting a variation per hour of the target vehicle speed to a predetermined value or less. And an output control unit for obtaining an output control command value for the engine based on a vehicle speed deviation between the target vehicle speed and the own vehicle speed after processing by the acceleration limiting unit.