JPH11278098A - Speed control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform speed control rule in feasible acceleration/deceleration time, by deriving speed of a related car (a preading car or a following car) from inter-vehicle distance and car speed of an own car, setting the speed as the car speed of the own car after a given time, and deriving constant acceleration/deceleration at a given time from specific arithmetic equations, and performing the acceleration/ deceleration control. SOLUTION: Using equation I and equation II, when inter-vehicle distance between an own car running at a car speed V at a certain time (t) and a related car running at a car speed V1 is d, the own car is accelerated to a target speed V1 after a time T and the inter-vehicle distance is transferred to a target inter-vehicle distance d1 . The target inter-vehicle distance d1 is derived from a coefficient α and the acceleration/ deceleration time T, a constant acceleration/deceleration V is derived at the given time T, and a control means for controlling an acceleration control means or a deceleration control means is provided. In these equations, sgn is 1 during following a preceding car and -1 during merging. A constant acceleration/deceleration control rule where a car speed reaches a target car speed at a target position or a target inter- vehicle distance can be applied, and the control rule can be applied to the entire speed control of automatic operation to uniformly express speed control rules during acceleration/deceleration.

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 traveling control and a distance between a vehicle and a preceding vehicle (hereinafter referred to as a preceding vehicle). It concerns the device.

[0002]

2. Description of the Related Art Conventionally, a constant speed which automatically adjusts an opening degree of a throttle valve as an engine output control means so that a driver's own vehicle speed can be kept constant without operating an accelerator pedal. Vehicles equipped with a traveling device (auto cruise) have become widespread.

[0003] In such a constant-speed traveling device, there is a possibility that the vehicle crashes into a preceding vehicle due to traffic congestion, and in order to prevent such a collision, the distance measurement of a laser radar, a radio wave radar or the like mounted on the own vehicle is performed. 2. Description of the Related Art A vehicle speed control device having a function of measuring an inter-vehicle distance with a preceding vehicle and preventing a rear-end collision using the device has been developed and put into practical use. Further, development of a function of preventing a collision with an obstacle or a traveling vehicle is also progressing.

[0004]

[Problems to be Solved by the Invention] However, since individual control technologies are being studied independently, automatic driving has been unified to prevent rear-end collision with vehicles and acceleration / merging to expressways. There was no necessary speed control law at the time of acceleration / deceleration.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize a speed control apparatus for a vehicle that has a unified speed control law at the time of acceleration and deceleration that is simple and practical and can cope with a series of speed controls.

[0006]

A process for deriving a unified speed control law during acceleration / deceleration in the vehicle speed control device according to the present invention for achieving the above object will be described below.

[0007] 1. If inter-vehicle distance to the preceding vehicle is a counterpart vehicle running at the vehicle and the vehicle speed V _t running at the vehicle speed V is derived a certain time t of the acceleration control law is d, the time t + T accelerating to the target vehicle speed V _t, consider that to achieve a simultaneous target inter-vehicle distance d _t. Incidentally, L ₁ is the vehicle travel distance, L ₂ denotes a preceding vehicle running distance. This situation is shown in FIG. Also shows the time variation of up to a vehicle speed V of the vehicle reaches the target vehicle speed V _t at a constant acceleration in FIG.

In FIG. 1, the following equation is established from the relationship between the inter-vehicle distance and the traveling distance.

(Equation 1)

Here, the traveling distances L ₁ and L ₂ are represented by the following equations.

(Equation 2)

By substituting this into equation (1), the following equation is obtained.

(Equation 3)

When the acceleration time T is obtained from the equation (3), the following equation is obtained.

(Equation 4)

On the other hand, the constant acceleration V 'is given by the following equation.

(Equation 5) Therefore, when equation (4) is substituted into this, the constant acceleration V ′ is given by the following equation.

(Equation 6)

Incidentally, since the acceleration time T is a positive number,
From equation (4), it is necessary that one of the following control rules (A) or (B) is satisfied. In other words,
Only when either of the conditions of the control law (A) or (B) is satisfied, the constant acceleration expression represented by Expression (6) is valid. (A) d> d _t and _{V> V t (B) d} <d t and V <V _t

The physical meanings of the control rules (A) and (B) can be interpreted as follows. (A) When the inter-vehicle distance d is wider than the target inter-vehicle distance _dt and the own vehicle speed V is faster than the target vehicle speed V _t (B) The inter-vehicle distance d is smaller than the target inter-vehicle distance _dt and the own vehicle speed V but the target vehicle speed V _t
If later

In each case, the sign of equation (6) differs as follows. In the case of (A): V '<0: constant deceleration control In the case of (B): V'> 0: constant acceleration control In other words, according to the control rules (A) and (B), In addition to the constant deceleration control shown in FIGS. 1 and 2,
It can be seen that the equation also corresponds to the constant acceleration control shown in FIGS.

2. Classification of control law 2.1 Front vehicle following control law The above equation (6) is a constant acceleration / deceleration control law that is effective only when the constraint condition (A) or (B) is satisfied. Consider a tracking control law. Therefore,
The necessary control law is divided into cases according to the inter-vehicle distance and the vehicle speed. FIG. 5 shows the cases.

In FIG. 5, the horizontal axis represents the inter-vehicle distance d, and the vertical axis represents the vehicle speed V. Inter-vehicle distance d and the vehicle the vehicle speed V, the the magnitude relationship with respect to the target inter-vehicle distance d _t and the target vehicle speed V _t, classifies control law from (A) to (F). (A)
And (B) are control rules corresponding to the constraints (A) and (B) described above.

Conditions (A) to (D) are front vehicle following control rules for realizing a target inter-vehicle distance and a target vehicle speed when the host vehicle is traveling behind the preceding vehicle. Note that the line d = _dt corresponds to a case of a constant inter-vehicle distance cruise.

[0019] 2.11 control law (C): shows the situation in d <d _t and V> V _t 6. Since it is closer than the target inter-vehicle distance d _t and the vehicle speed V is fast, it is necessary to decelerate. Time t + T
To become the target inter-vehicle distance d _t, obtains a constant deceleration for the vehicle speed at that time becomes slower alpha] V _t than the target vehicle speed V _t.

In FIG. 6, the above equation (1) is established from the relationship between the inter-vehicle distance and the traveling distance.
The following equation is obtained from the following equation.

(Equation 7)

Substituting this into equation (1) gives the following equation.

(Equation 8)

When the deceleration time T is obtained from the equation (8), the following equation is obtained.

(Equation 9)

Here, since the deceleration time T is a positive number and d < _dt ,

(Equation 10) And therefore

[Equation 11] Is necessary, and the coefficient α needs to be set so as to satisfy this condition.

[0024] Since the case of V> V _t, the coefficient from the equation (11) α
Is a positive number smaller than 1. This is the only approach the target vehicle speed to the deceleration and unless the preceding vehicle strongly as V _t than slow αV _t, which means that you can not achieve the target inter-vehicle distance d _t.

From the equation (5), the constant deceleration (-V ') is given by

(Equation 12) Therefore, when equation (9) is substituted, it is expressed by the following equation.

(Equation 13)

[0026] 2.12 control law (D): shows the situation d> d _t and V <V _t 8. Since it is longer than the target inter-vehicle distance _dt and the vehicle speed V is slow, it is necessary to accelerate. At time t + T, becomes a target inter-vehicle distance d _t, obtains a constant acceleration for the vehicle speed at that time becomes faster alpha] V _t than the target vehicle speed V _t.

Also in FIG. 8, equations (7) to (9) are established from the relationship between the inter-vehicle distance and the traveling distance. Where deceleration time
Since T is a positive number and d> d _t :

[Equation 14] And therefore

(Equation 15) Is required, and the coefficient α needs to be set so as to satisfy this condition.

[0028] Since the case of V <V _t, is α from the equation (15) it can be seen that a large positive number than one. This is the target vehicle speed
If a faster αV _t V _t, which means that it is not possible to achieve the target vehicle-to-vehicle distance d _t by narrowing the distance between vehicles.

Therefore, the constant acceleration V 'is calculated from the equation (5) in the same manner as in the case of the control law (C).

(Equation 16) Therefore, the following equation is obtained by substituting equation (9).

[Equation 17]

2.2 Merging Control Law In FIG. 5, the control laws (E) and (F) represent the region of merging control. That is, each of the above control rules (A) to
(D) is always opponent vehicle was preceding vehicle, as shown in FIG. 10, if to the counterpart vehicle traveling the main lane by the vehicle speed V _t, meet at target inter-vehicle distance d _t, the inter-vehicle distance is 0 Until the point (when the rear end of the opponent vehicle and the front end of the own vehicle are aligned side by side), it is assumed that the opponent vehicle is the rear vehicle, and thereafter the opponent vehicle is switched to the preceding vehicle.

[0031] 2.21 control law (E): V> V _t the vehicle speed V is the case faster than the main line vehicle speed V _t, then decelerated to αV _t, consider the fact that to achieve the target vehicle-to-vehicle distance d _t.

Also in FIG. 10, the following equation is established from the relationship between the inter-vehicle distance and the traveling distance.

(Equation 18)

Here, since the traveling distance is represented by equation (7), the following equation is obtained by substituting equation (7) into equation (1).

[Equation 19]

When the deceleration time T is obtained from the equation (19), the following equation is obtained.

(Equation 20)

Here, since the deceleration time T is a positive number,

(Equation 21) Becomes

(Equation 22) Is necessary, and the coefficient α needs to be set so as to satisfy this condition.

[0036] Since the case of V> V _t, is α from the equation (22) 1
It turns out that it is a smaller positive number. This means that you have to decelerate strongly the target vehicle speed as the main line vehicle speed V _t from late αV _t.

Therefore, the constant deceleration (-V ') is

(Equation 23) The following equation is obtained by substituting equation (20) into this.

(Equation 24)

[0038] 2.22 control law (F): V <V _t the vehicle speed V is a case slower than the main line vehicle speed V _t, merge to accelerate. The situation is shown in FIG.

In FIG. 13, equation (18) is established from the relationship between the inter-vehicle distance and the traveling distance, and the traveling distance is represented by the following equation.

(Equation 25)

By substituting this into equation (18), the following equation is obtained.

(Equation 26)

When the deceleration time T is obtained from the equation (26), the following equation is obtained.

[Equation 27]

Therefore, the constant acceleration V 'is

[Equation 28] The following equation is obtained by substituting equation (27) into this.

(Equation 29)

3. Unified expression of control law Let us consider that the above control rules (A) to (F) are organized and expressed. The difference in the expression of these control rules is the presence or absence of the coefficient α, but the control rules (A), (B), and (F) without the coefficient α
The equation for the constant acceleration / deceleration V ′ in the case of (1) is exactly the same as the equation for the control rules (C), (D), and (E) using the coefficient α, where α is set to 1.

Taking these into consideration, the front vehicle following control law and the merging control law can be unified as shown in Table 1 below.

[Table 1]

4. Calculation of the coefficient α Depending on the value of the coefficient α, the acceleration / deceleration time T may be excessively long. Therefore, the acceleration / deceleration time T (for example, 100 s) is given in advance, and α is calculated back from the acceleration / deceleration time T and used.

That is, by solving the equation for the acceleration / deceleration time T shown in Table 1 with respect to α, the following equation can be obtained.

[Equation 30]

Then, the coefficient α obtained by the equation (30) is calculated by the equation (1).
By substituting into 3) or (17), the acceleration / deceleration V ′ can be obtained.

Therefore, the control means calculates the acceleration / deceleration V '
Is given to the acceleration control means or the deceleration control means, so that acceleration or deceleration control corresponding to each of the above control rules can be performed.

[0049]

FIG. 14 shows an embodiment of a vehicle speed control apparatus according to the present invention, wherein 1 is an inter-vehicle distance sensor such as a radar apparatus, 2 is a vehicle speed sensor, and 3 is control means. Controllers 4, 4 and 5 are a throttle valve driving device and a throttle valve respectively constituting acceleration control means, and 6 and 7 are a brake driving device and a foot brake valve respectively constituting deceleration control means. The acceleration control means 4 and 5 are not limited to the throttle valve, but may be a fuel injection amount control means such as a control rack of a fuel injection pump if applied to a diesel engine. Means 6 and 7 are not limited to the foot brake valve, and it goes without saying that auxiliary brakes such as an exhaust brake and a retarder may be used.

In such an embodiment, in order to confirm the effectiveness of the control rules (A) to (F) shown in Table 1 above, the following verification was performed by vehicle speed control simulation. (1) Simulation conditions Here, the control rules (A), (C),
(E) and control rules (B), (D),
The example of the simulation of (F) is shown.

Depending on the acceleration performance and deceleration performance of the vehicle, even when the vehicle reaches the target speed, it is not always possible to reduce the inter-vehicle distance to the target vehicle. In Table 2 below, appropriate calculation conditions that can be realized are set in the sense of showing examples only.

[0052]

[Table 2]

(2) Simulation Results FIGS. 15 and 16 show simulation results (time vs. own vehicle speed V and inter-vehicle distance d) in the deceleration mode and the acceleration mode, respectively. FIG. 17 shows the relative relationship between the own vehicle speed V and the inter-vehicle distance d of each simulation result.

FIG. 7A shows a simulation result of the control law (A). Here, the inter-vehicle distance is the initial 300m
, The vehicle decelerates at a substantially constant acceleration while reaching the target 250 m, and reaches the target vehicle speed at the target inter-vehicle distance (see graph A in FIG. 17).

FIG. 15B shows a simulation result of the control law (C). Here, the inter-vehicle distance d once decreases from the relative speed between the own vehicle and the preceding vehicle at the start of the deceleration control, increases from the time when the own vehicle becomes slower than the speed of the preceding vehicle, and finally increases. Target speed at target distance of 250m
It has reached the V _t (see the graph C in Fig. 17).

FIG. 15C shows a simulation result of the control law (E). Here, the front-back relationship between the own vehicle and the other vehicle at the start of the acceleration control is opposite to the control law (C), and the own vehicle precedes.

The inter-vehicle distance d once decreases (actually, the inter-vehicle distance increases) based on the relative speed between the own vehicle and the preceding vehicle (at this time, the opponent vehicle is running behind the own vehicle) at the start of the deceleration control. Here, by defining the own vehicle as the origin and defining the traveling direction as the positive direction, the inter-vehicle distance at the start of the control is treated as a negative value), and the speed of the own vehicle becomes lower than the vehicle speed of the preceding vehicle. Increase from the point of time (d goes in the positive direction)
And, finally reaches the target speed V _t at the target inter-vehicle 250 meters (see graph E in FIG. 17).

FIG. 16A shows a simulation result of the control law (B). Here, the inter-vehicle distance is the initial 80m
, The vehicle accelerates at a constant acceleration while spreading to the target 250 m, and reaches the target vehicle speed at the target inter-vehicle distance (see graph B in FIG. 17).

FIG. 16B shows a simulation result of the control law (D). Here, the inter-vehicle distance d increases once from the relative speed between the own vehicle and the preceding vehicle at the start of the acceleration control, and decreases from the time when the own vehicle becomes faster than the speed of the preceding vehicle. and the target inter-vehicle 250m reaches the target velocity V _t (see graph D in FIG. 17). FIG. 16C shows a simulation result of the control law (F). Here, the front-back relationship between the own vehicle and the opponent vehicle at the start of the acceleration control is the control rule B.
Conversely, the own vehicle leads. However, as in the case of the control law (B), the vehicle accelerates at a constant acceleration and reaches the target vehicle speed at the target inter-vehicle distance (see graph F in FIG. 17).

From the above results, the control laws (A), (B),
In (C), (D), (E), and (F), the function of reaching the target vehicle speed at the target inter-vehicle distance was confirmed.

[0061]

As described above, according to the speed control apparatus for a vehicle according to the present invention, the speed of the opponent vehicle (preceding vehicle or rear vehicle) is obtained from the inter-vehicle distance and the vehicle speed. And the acceleration / deceleration control is performed by obtaining a constant acceleration / deceleration for the predetermined time by a predetermined arithmetic expression. Therefore, a constant acceleration / deceleration control law that reaches the target vehicle speed at the target position or the target inter-vehicle distance is established. It can be applied and can be extended to control following the opponent vehicle and control at the time of merging.
As a result, the following specific effects can be obtained.

Since the speed control law at the time of acceleration / deceleration is expressed in a unified manner, it can be applied to a whole series of speed controls required for automatic operation, is simple and easy to implement, and is the basis of speed control for automatic operation. A control law is obtained. Unlike the conventional method in which a plurality of independent control rules are switched according to the situation, continuous acceleration / deceleration control can be performed consistently even when the situation changes.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of following a front vehicle (control law B) by constant acceleration control in a vehicle speed control device according to the present invention.

FIG. 2 is a diagram showing an acceleration pattern (control law B) in the vehicle speed control device according to the present invention.

FIG. 3 is a diagram showing a state of following a front vehicle (control law A) by constant deceleration control in the vehicle speed control device according to the present invention.

FIG. 4 is a diagram showing a deceleration pattern in a control law (A) in the vehicle speed control device according to the present invention.

FIG. 5 is a diagram showing a classification of a control law based on an inter-vehicle distance and a vehicle speed in a vehicle speed control device according to the present invention.

FIG. 6 is a diagram showing a state of a control law (C) in the vehicle speed control device according to the present invention.

FIG. 7 is a diagram showing a deceleration pattern in a control law (C) in the vehicle speed control device according to the present invention.

FIG. 8 is a diagram showing a state of a control law (D) in the vehicle speed control device according to the present invention.

FIG. 9 is a diagram showing an acceleration pattern in a control law (D) in the vehicle speed control device according to the present invention.

FIG. 10 is a diagram showing a state of a control law (E) in the vehicle speed control device according to the present invention.

FIG. 11 is a diagram showing a deceleration pattern in a control law (E) in the vehicle speed control device according to the present invention.

FIG. 12 is a diagram showing a state of a control law (F) in the vehicle speed control device according to the present invention.

FIG. 13 is a diagram showing an acceleration pattern in a control law (E) in the vehicle speed control device according to the present invention.

FIG. 14 is a block diagram showing one embodiment of a vehicle speed control device according to the present invention.

FIG. 15 is a graph showing a simulation result in a deceleration mode according to an embodiment of the vehicle speed control device according to the present invention.

FIG. 16 is a graph showing a simulation result in the acceleration mode by the embodiment of the vehicle speed control device according to the present invention.

FIG. 17 is a graph showing the simulation results in FIGS. 15 and 16 as a relationship between the inter-vehicle distance and the vehicle speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radar apparatus 2 Vehicle speed sensor 3 Controller 4 Throttle valve drive 5 Throttle valve 6 Brake drive 7 Foot brake valve In a figure, the same code shows the same or the corresponding part.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinjiro Endo No. 8 Dosanabe, Fujisawa-shi, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. In-house (72) Inventor Kitagawa No. 2-12-1, Ookayama, Meguro-ku, Tokyo Tokyo Institute of Technology Faculty of Engineering, Department of Control Systems Engineering (72) Inventor Kazushi Sanada 2-1-1, Ookayama, Meguro-ku, Tokyo Tokyo Institute of Technology Faculty of Engineering Control System Engineering

Claims (2)

[Claims] 1. An inter-vehicle distance detecting means between the other vehicle and the own vehicle, a vehicle speed detecting means of the own vehicle, an acceleration control means, a deceleration control means, and a speed of the other vehicle based on the inter-vehicle distance d and the vehicle speed V. following equation coefficients α a target inter-vehicle distance as d _t with the target vehicle speed V _t of the vehicle after a predetermined time T has elapsed seek, Equation 31] And a constant acceleration / deceleration V ′ at the predetermined time T.
Is given by the following equation: Control means for controlling the acceleration control means or the deceleration control means as determined by the following formula: 2. The vehicle according to claim 1, wherein the opponent vehicle is always the preceding vehicle during the preceding vehicle follow-up control, and the preceding vehicle is switched from the rear vehicle to the preceding vehicle at the time when the inter-vehicle distance becomes zero during the merge control. A speed control device for a vehicle, characterized in that: