JP4060421B2

JP4060421B2 - Inter-vehicle distance control device

Info

Publication number: JP4060421B2
Application number: JP35923797A
Authority: JP
Inventors: 博文東田
Original assignee: Denso Ten Ltd
Current assignee: Denso Ten Ltd
Priority date: 1997-12-26
Filing date: 1997-12-26
Publication date: 2008-03-12
Anticipated expiration: 2017-12-26
Also published as: JPH11189069A

Description

【０００１】
【発明の属する技術分野】
本発明は、車速を一定速度に制御する定速走行中において、衝突防止のため先行車との車間距離を所定の距離に保つように車速を制御して追従走行を行う車間距離制御装置に関する。
【０００２】
【従来の技術】
高速道路等での走行時等に便利な制御装置として車間距離制御装置がある。この車間距離制御装置は、車速を所望の車速に保つ定速走行制御中に、衝突防止のためにレーダ等で測定された車間距離を用いて車速を制御して安全車間距離を保つ制御を行う。このような車間距離制御装置では、一定の車速での走行中に先行車を検知すると、自車の速度を減速、或いは加速して、検知した先行車に追随する自車の車速に応じた車間距離に調整するように制御する。
【０００３】
【発明が解決しようとする課題】
これまでの車間距離制御装置では、予め演算テーブル等に車速に応じた目標車間距離を設定し、測定した車間距離がこの目標車間距離となるように車速を制御していた。例えば図６に示すように車速と車間距離の関係（概略、適正車間距離は車速の２乗に比例する）を記憶しておき、ここから測定した車速に対応した車間距離を読み出し、目標車間距離とする。
【０００４】
このような車間距離制御では、前方車両を検知した場合、図７に示すように、実車間距離の減少に伴って車速を低下する制御が行われるため、目標車間距離も低下する。このため、実車間距離と目標車間距離の差が大きくなり、場合によっては、実車間距離と目標車間距離の大きさの関係が反転する。この場合、今度は加速制御を行うことになり、その結果、再度実車間距離と目標車間距離の大きさの関係が反転すことが生じる場合があり、今度は減速制御となる。このような制御状態になると、減速と加速が繰り返し行われ、乗り心地が悪くなる問題がある。
【０００５】
本発明は、このような課題を解決するもので、車間距離制御を適切に行い、乗り心地等が良好な車間距離制御装置を実現することを特徴とする。
【０００６】
【課題を解決するための手段】
本発明は上述の課題を解決するもので、実車速が目標車速を保つように車両の走行用アクチュエータを制御する定速走行手段と、自車と先行車の車間距離を検知する車間距離検知手段と、該車間距離検知手段により検出された先行車との車間距離が目標車間距離になるように車両の走行用アクチュエータを制御する車間距離制御手段とを有する車間距離制御装置において、前記目標車間距離を実車速に応じて設定する目標車間距離設定手段と、前記目標車間距離設定手段により設定された目標車間距離と、前記車間距離検知手段により検知された実車間距離との偏差を検出する偏差検出手段と、前記偏差検出手段により検出された偏差が第１所定値以下となった時に、前記目標車間距離設定手段に前記目標車間距離の設定動作を行わせる第１起動手段とを有することを特徴とする。
【０００７】
また、前記第１起動手段が目標車間距離の設定動作を行ってから時間を計測する時間計測手段と、前記時間計測手段が検出した時間に応じた値に前記第１所定値を設定する第１所定値設定手段とを有することを特徴とする。また、前記偏差検出手段が検出した偏差が前記第１所定値より大きい第２所定値以上となった時に、前記目標車間距離設定手段に前記目標車間距離の設定動作を行わせる第２起動手段を有することを特徴とする。
【０００８】
また、自車と先行車の相対速度を検知する相対速度検知手段と、前記相対速度検知手段が検出した相対速度に応じた値に前記第２所定値を設定する第２所定値設定手段とを有することを特徴とする。
【０００９】
【実施例】
次に、本発明の一実施例である車間距離制御装置を説明する。図１は、本発明の一実施例における車間距離制御装置の構成を示す構成図である。
１は、ミリ波やレーザ光線等の電磁波を用いて、先行車等との車間距離等を検出して信号出力するレーダ装置である。レーダ装置１は、車両前方にむけてミリ波やレーザ光線等の電磁波を放射し、前方物体からの反射エコー信号を受信し、受信したエコー信号から前車との車間距離、或いは相対速度を演算し、演算結果を出力する。２は、車輪の回転速度等を検出して自車の速度を出力する車速センサである。３は、定速走行制御中に手動操作で速度を上げるために操作するアクセルスイッチで、ハンドル付近に設置される。４は、定速走行制御中に手動操作で速度を下げるために操作するコーストスイッチで、ハンドル付近に設置される。５は、定速走行制御における走行速度を設定するためのセットスイッチで、ハンドル付近に設置され、運転者が操作した時の実際の速度が定速走行制御の目標車速として設定される。６は、車間距離制御、定速走行制御等を行うためのマイコン（マイクロコンピュータ）で、ＣＰＵ６１、ＲＡＭ６２、ＲＯＭ６３等で構成される。なお、ＣＰＵ６１は入力された信号やプログラムに基づき演算制御等を行う機能素子、ＲＡＭ６２は例えば演算用のデータが記憶される書換え可能な記憶素子、ＲＯＭ６３は例えば制御用のプログラムやデータが記憶される読み出し専用の記憶素子である。７は、エンジンの吸気管に設置されてスロットル弁を回動しその開度をマイコン６からの入力信号に応じて加減して調整するスロットルアクチュエータであり、ステッピングモータ等により構成される。８は、マイコン６からの信号に応じてブレーキを駆動するブレーキアクチュエータで、ブレーキの油圧系統に設けられた油圧バルブ等により構成される。
【００１０】
次に、車間距離制御に関し制御部１の行う処理を説明する。
図２は制御部１の行う車間距離制御のフローチャートである。この処理は、車間距離制御装置が起動している状態（車間距離制御中）で、他の定速走行制御処理等の車両制御処理と共に繰り返し行われる。ステップＳ１では、適正車間距離Ｄｖを演算し、ステップＳ２に移る。この適正車間距離Ｄｖの演算は、図６に示すように車速と車間距離の関係（概略、適正車間距離は車速の２乗に比例する）を記憶しておき、現在の車速に対応した車間距離を読み出し、適正車間距離Ｄｖとする。ステップＳ２では、車間距離の第２偏差値ΔＤ₂＝ｆ（Ｖｒ）を演算し、ステップＳ３に移る。この第２偏差値ΔＤ₂は、目標車間距離の設定動作を開始させる第２起動手段の起動閾値となるものであって、図５に示すように、第２偏差値ΔＤ₂と、自車と先行車の相対速度Ｖｒとの関係（相対速度Ｖｒの１次関数で、相対速度Ｖｒが０でオフセット値Ｆとする）を記憶しておき、相対速度Ｖｒに対応した第２偏差値ΔＤ₂を読み出す方法により算出される。図５に示したように本実施例では、相対速度Ｖｒが大きいほど、つまり接近の度合いが高いほど第２偏差値ΔＤ₂を大きく設定したが、これは接近の度合いが高いほど現在の実車間距離Ｄｔと目標車間距離Ｄｋが急速に接近しており実車間距離Ｄｔと目標車間距離Ｄｋとの差が比較的大きな段階から目標車間距離Ｄｋを再設定しないと制御が遅れて、適切な走行制御を行えないためである。なお、オフセットＦおよび傾きは、適切な実車間距離Ｄｔで第１偏差値ΔＤ₁による制御が始まるように設定した定数である。ステップＳ３では、（実車間距離Ｄｔ−目標車間距離Ｄｋ）の値が第２偏差値ΔＤ₂より大きいか判断し、大きければステップＳ６に移り、大きくなければステップＳ４に移る。ステップＳ４では、車間距離の第１偏差値ΔＤ₁＝ｇ（ｔ）を演算し、ステップＳ５に移る。この車間距離の第１偏差値ΔＤ₁は、目標車間距離の設定動作を行わせる第１起動手段の起動閾値となるものであって、図４に示すように車間距離の第１偏差値ΔＤ₁と、目標車間距離Ｄｋ更新後の経過時間ｔとの関係（更新後の経過時間ｔの１次関数で、時間ｔが０でオフセット値Ｃとする）を記憶しておき、更新後の経過時間ｔに対応した第１偏差値ΔＤ₁を読み出す方法により算出される。図４に示したように本実施例では、更新後の経過時間ｔが大きくなると、第１偏差値ΔＤ₁を大きくするようにしたが、これは一旦固定（ステップＳ４、ステップＳ５Ｎの経路が継続）した目標車間距離Ｄｋが続き、その経過時間ｔが長くなりすぎないように、経過時間ｔが大きいほどＤｔとＤｋの偏差が同一水準でも更新判断が出易くなるよう条件を設定したものである。なお、オフセットＣ及び傾きは、目標車間距離Ｄｋの設定後、次に更新するまでの時間間隔が適切な水準になるよう設定した定数である。ステップＳ５では、（実車間距離Ｄｔ−目標車間距離Ｄｋ）の値が第１偏差値ΔＤ₁より大きいか判断し、大きくなければステップＳ６に移り、大きければステップＳ８へ移る。ステップＳ６では、演算した適正車間距離Ｄｖをもって目標車間距離Ｄｋを更新し、ステップＳ７に移る。ステップＳ７では、目標車間距離Ｄｋの更新からの経過時間を計測するカウンタｔを０とし、ステップＳ８へ移る。ステップＳ８では、スロットルアクチュエータ７、ブレーキアクチュエータ８等の制御量を演算し、ステップＳ９へ移る。ステップＳ９では、スロットルアクチュエータ７、ブレーキアクチュエータ８等へ制御量信号を出力し、本処理を終わる。なお、第２偏差値ΔＤ₂は第１偏差値ΔＤ₁より大きな数値となるよう設定されている。
【００１１】
以上のような処理により、車間距離制御が始まった段階では、車間距離制御の基本的な動作（車速に基づく適正車間距離Ｄｖを目標車間距離Ｄｋとした制御）が行われる。次に、先行車との車間距離が縮まり、実車間距離Ｄｔと目標車間距離Ｄｋとの差が第２偏差値ΔＤ₂となると、第１偏差値ΔＤ₁を用いた車間距離制御の動作に切換えられる。この動作切換えが行われると、目標車間距離Ｄｋには動作が切換った時点の適正車間距離Ｄｖの値が用いられ、次に述べる目標車間距離Ｄｋの更新の時点まで目標車間距離Ｄｋは固定してもちいられる。また、同時に経過時間のカウンタｔがリセットされる。その後、このカウンタｔに基づく第１偏差値ΔＤ₁を用いて目標車間距離Ｄｋの更新の判断動作が行われる。更新判断動作中に、実車間距離Ｄｔと目標車間距離Ｄｋとの差が第１偏差値ΔＤ₁（図４で求める）に達すると、目標車間距離Ｄｋがその時点の車速に基づく適正車間距離Ｄｖの値に更新される。このようにして設定、更新された目標車間距離Ｄｋに基づき、実車間距離Ｄｔと目標車間距離Ｄｋとの差異が判断され、車間距離制御の基本的な動作である車速の加減速制御が行われる。なお、更新した時点で時間カウンタｔはリセットされる。このようにして、実車間距離Ｄｔが目標車間距離Ｄｋに近づき、車速に応じた車間距離に収斂する。
【００１２】
その状況を、次に図３を用いて説明する。
図３は、車速Ｖと車間距離Ｄの推移図である。縦軸を車速Ｖ、および車間距離Ｄ、横軸を経過した時間ｔとし、車間距離制御による車速Ｖ、および車間距離Ｄの変化状況を示している。本図では、Ｄｔは現在の実車間距離、Ｄｋは目標車間距、Ｄｖは現在の車速に応じた適正車間距離、ΔＤ₁は第１偏差値、ΔＤ₂は第２偏差値である。
【００１３】
図３の時刻０では、車速に基づく適正車間距離Ｄｖ（ステップＳ１）を目標車間距離Ｄｋとし、車間距離制御の基本的な動作が行われており、時間経過とともに車速を減速しながら実在の車間距離Ｄｔを目標車間距離Ｄｋへ漸次近づけている。時間が経過しても、（実車間距離Ｄｔ−目標車間距離Ｄｋ）が第２偏差値ΔＤ₂（ステップＳ２）よりも大きい間は、基本的な車間距離制御の動作が継続される。
【００１４】
次に、時刻ｔ_Aは縮小してきた車間距離の差異（実車間距離Ｄｔ−目標車間距離Ｄｋ）が第２偏差値ΔＤ₂に達した（ステップＳ３で判断）時点であって、この時点で、目標車間距離Ｄｋが時刻ｔ_Aでの車速に応じた適正車間距離Ｄｖに設定（ステップＳ４、ステップＳ５Ｙの経路）される。引き続き、時間経過と共に実車間距離Ｄｔが減少しても、車間距離の差異（実車間距離Ｄｔ−目標車間距離Ｄｋ）が第１偏差値ΔＤ₁（ステップＳ４）に到達するまでの経過時間ｔ₁の間は、目標車間距離Ｄｋは経過時間ｔ₁の間、時刻ｔ_Aで設定された値に固定・保持（ステップＳ４、ステップＳ５Ｙの経路）される。
【００１５】
次に、時刻ｔ_Bは縮小してきた車間距離の差異（実車間距離Ｄｔ−目標車間距離Ｄｋ）がΔＤ₁₁（第１偏差値ΔＤ₁）に達した（ステップＳ５で判断）時点であって、この時点で、目標車間距離Ｄｋが時刻ｔ_Bでの車速に応じた適正車間距離Ｄｖに設定・更新（ステップＳ６）される。この目標車間距離Ｄｋ（時刻ｔ_Bでの適正車間距離Ｄｖの値）は、続く時間ｔ₂を経過して時刻ｔ_Cに到り、車間距離の差異（実車間距離Ｄｔ−目標車間距離Ｄｋ）がΔＤ₁₂（第１偏差値ΔＤ₁）に到達する（時刻ｔ_C）まで固定して用いられる。以後、同様に目標車間距離Ｄｋの更新が繰り返される。
【００１６】
以上のように、車間距離の差異（実車間距離Ｄｔ−目標車間距離Ｄｋ）が第２偏差値ΔＤ₂（相対速度により可変）以下では、目標車間距離Ｄｋを固定し、併せて固定する期間を車間距離の差異が第１偏差値ΔＤ₁以上の期間とし、この目標車間距離Ｄｋに基づいて車間距離制御の基本的な動作を行うので、時間経過とともに車速を減速しながら実車間距離Ｄｔを目標車間距離Ｄｋへ収斂することができ、従来の車速に応じた適正車間距離Ｄｖで最終段階まで制御する場合に比べ、車速制御量が過剰に作用することがなくなり、車速制御に伴う車速の上下変動が回避される。
【００１７】
【発明の効果】
以上詳細に説明したように、本発明による車間距離制御装置によれば、車間距離が目標値に近くになってからの、車速制御量が無駄に変動することによる乗り心地の劣化を回避できる。
【図面の簡単な説明】
【図１】本発明の一実施例の車間距離制御装置の構成を示す構成図である。
【図２】制御部６の行う処理のフローチャートである。
【図３】車速Ｖと車間距離Ｄの推移図である。
【図４】更新後の時間ｔと第１偏差値ΔＤ₁の特性図である。
【図５】相対速度Ｖｒと第２偏差値ΔＤ₂の特性図である。
【図６】車速Ｖと適正車間距離Ｄｖの特性図である。
【図７】従来の制御における車速Ｖと車間距離Ｄの推移図である。
【符号の説明】
１・・・レーダ装置
２・・・車速センサ
３・・・アクセルスイッチ
４・・・コーストスイッチ
５・・・セットスイッチ
６・・・マイコン
７・・・スロットルアクチュエータ
８・・・ブレーキアクチュエータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inter-vehicle distance control device that performs a follow-up travel by controlling the vehicle speed so as to keep the inter-vehicle distance from a preceding vehicle at a predetermined distance to prevent a collision during constant-speed travel that controls the vehicle speed at a constant speed.
[0002]
[Prior art]
There is an inter-vehicle distance control device as a control device that is convenient when traveling on an expressway or the like. This inter-vehicle distance control device performs control to maintain a safe inter-vehicle distance by controlling the vehicle speed using the inter-vehicle distance measured by a radar or the like to prevent a collision during constant speed running control that keeps the vehicle speed at a desired vehicle speed. . In such an inter-vehicle distance control device, when a preceding vehicle is detected during traveling at a constant vehicle speed, the speed of the host vehicle is decelerated or accelerated, and the inter-vehicle distance corresponding to the detected vehicle speed following the preceding vehicle is detected. Control to adjust to the distance.
[0003]
[Problems to be solved by the invention]
In conventional inter-vehicle distance control devices, a target inter-vehicle distance corresponding to the vehicle speed is set in advance in a calculation table or the like, and the vehicle speed is controlled so that the measured inter-vehicle distance becomes the target inter-vehicle distance. For example, as shown in FIG. 6, the relationship between the vehicle speed and the inter-vehicle distance (roughly, the appropriate inter-vehicle distance is proportional to the square of the vehicle speed) is stored, the inter-vehicle distance corresponding to the measured vehicle speed is read out from this, and the target inter-vehicle distance And
[0004]
In such inter-vehicle distance control, as shown in FIG. 7, when a vehicle ahead is detected, control is performed to decrease the vehicle speed as the actual inter-vehicle distance decreases, so the target inter-vehicle distance also decreases. For this reason, the difference between the actual inter-vehicle distance and the target inter-vehicle distance increases, and in some cases, the relationship between the actual inter-vehicle distance and the target inter-vehicle distance is reversed. In this case, acceleration control is performed this time, and as a result, the relationship between the actual inter-vehicle distance and the target inter-vehicle distance may be reversed again, and this time deceleration control is performed. In such a control state, there is a problem that deceleration and acceleration are repeatedly performed, resulting in poor ride comfort.
[0005]
The present invention solves such a problem, and is characterized in that an inter-vehicle distance control device that appropriately performs inter-vehicle distance control and has good riding comfort and the like is provided.
[0006]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and is a constant speed traveling means for controlling a vehicle travel actuator so that the actual vehicle speed is maintained at a target vehicle speed, and an inter-vehicle distance detecting means for detecting the inter-vehicle distance between the host vehicle and a preceding vehicle. And an inter-vehicle distance control device that controls an actuator for driving the vehicle so that the inter-vehicle distance from the preceding vehicle detected by the inter-vehicle distance detection unit becomes the target inter-vehicle distance. Deviation detection for detecting a deviation between the target inter-vehicle distance setting means for setting the vehicle speed according to the actual vehicle speed, the target inter-vehicle distance set by the target inter-vehicle distance setting means, and the actual inter-vehicle distance detected by the inter-vehicle distance detection means And a first setting for causing the target inter-vehicle distance setting means to perform the setting operation of the target inter-vehicle distance when the deviation detected by the deviation detecting means is equal to or less than a first predetermined value. And having a motion means.
[0007]
In addition, a time measuring unit that measures time after the first activation unit performs the target inter-vehicle distance setting operation, and a first predetermined value that is set to a value corresponding to the time detected by the time measuring unit. And a predetermined value setting means. And a second activation unit that causes the target inter-vehicle distance setting unit to perform the setting operation of the target inter-vehicle distance when the deviation detected by the deviation detection unit becomes equal to or greater than a second predetermined value that is greater than the first predetermined value. It is characterized by having.
[0008]
A relative speed detecting means for detecting a relative speed between the host vehicle and the preceding vehicle; and a second predetermined value setting means for setting the second predetermined value to a value corresponding to the relative speed detected by the relative speed detecting means. It is characterized by having.
[0009]
【Example】
Next, an inter-vehicle distance control device that is an embodiment of the present invention will be described. FIG. 1 is a configuration diagram showing a configuration of an inter-vehicle distance control device in an embodiment of the present invention.
Reference numeral 1 denotes a radar apparatus that detects an inter-vehicle distance from a preceding vehicle or the like using electromagnetic waves such as millimeter waves or laser beams and outputs a signal. The radar device 1 emits an electromagnetic wave such as a millimeter wave or a laser beam toward the front of the vehicle, receives a reflected echo signal from a front object, and calculates an inter-vehicle distance or a relative speed from the received vehicle from the received echo signal. And output the calculation result. Reference numeral 2 denotes a vehicle speed sensor that detects the rotational speed of the wheels and outputs the speed of the host vehicle. Reference numeral 3 denotes an accelerator switch that is operated to increase the speed by manual operation during constant speed traveling control, and is installed near the steering wheel. Reference numeral 4 denotes a coast switch that is operated to reduce the speed by manual operation during constant speed traveling control, and is installed near the steering wheel. Reference numeral 5 denotes a set switch for setting the traveling speed in the constant speed traveling control, which is set near the steering wheel, and the actual speed when operated by the driver is set as the target vehicle speed for the constant speed traveling control. Reference numeral 6 denotes a microcomputer for performing inter-vehicle distance control, constant speed running control, and the like, and includes a CPU 61, a RAM 62, a ROM 63, and the like. The CPU 61 is a functional element that performs arithmetic control or the like based on an input signal or program, the RAM 62 is a rewritable storage element that stores, for example, calculation data, and the ROM 63 stores, for example, a control program or data. This is a read-only memory element. A throttle actuator 7 is installed in the intake pipe of the engine and rotates a throttle valve to adjust its opening degree according to an input signal from the microcomputer 6, and is constituted by a stepping motor or the like. Reference numeral 8 denotes a brake actuator that drives a brake in response to a signal from the microcomputer 6, and is constituted by a hydraulic valve or the like provided in a brake hydraulic system.
[0010]
Next, the process which the control part 1 performs regarding inter-vehicle distance control is demonstrated.
FIG. 2 is a flowchart of the inter-vehicle distance control performed by the control unit 1. This process is repeatedly performed together with other vehicle control processes such as a constant speed traveling control process in a state where the inter-vehicle distance control device is activated (during inter-vehicle distance control). In step S1, an appropriate inter-vehicle distance Dv is calculated, and the process proceeds to step S2. As shown in FIG. 6, the calculation of the appropriate inter-vehicle distance Dv stores the relationship between the vehicle speed and the inter-vehicle distance (roughly, the appropriate inter-vehicle distance is proportional to the square of the vehicle speed), and the inter-vehicle distance corresponding to the current vehicle speed. Is read out and set as an appropriate inter-vehicle distance Dv. In step S2, the second deviation value ΔD ₂ = f (Vr) of the inter-vehicle distance is calculated, and the process proceeds to step S3. This second deviation value ΔD ₂ serves as an activation threshold value of the second activation means for starting the setting operation of the target inter-vehicle distance, and as shown in FIG. 5, the second deviation value ΔD ₂ , The relationship with the relative speed Vr of the preceding vehicle (a linear function of the relative speed Vr, where the relative speed Vr is 0 and the offset value is F) is stored, and a second deviation value ΔD ₂ corresponding to the relative speed Vr is stored. Calculated by the reading method. As shown in FIG. 5, in this embodiment, the larger the relative speed Vr, that is, the higher the degree of approach, the larger the second deviation value ΔD ₂ is set. If the distance Dt and the target inter-vehicle distance Dk are rapidly approaching and the difference between the actual inter-vehicle distance Dt and the target inter-vehicle distance Dk is relatively large, the control will be delayed unless the target inter-vehicle distance Dk is reset. This is because it cannot be performed. The offset F and the slope are constants set so that the control based on the first deviation value ΔD ₁ starts at an appropriate actual inter-vehicle distance Dt. In step S3, it is determined whether the value of (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) is larger than the second deviation value ΔD _{2. If} larger, the process proceeds to step S6, and if not greater, the process proceeds to step S4. In step S4, the first deviation value ΔD ₁ = g (t) of the inter-vehicle distance is calculated, and the process proceeds to step S5. The first deviation value ΔD ₁ of the inter-vehicle distance serves as an activation threshold value of the first activation means for performing the setting operation of the target inter-vehicle distance, and as shown in FIG. 4, the first deviation value ΔD ₁ of the inter-vehicle distance. And the elapsed time t after the update of the target inter-vehicle distance Dk (a linear function of the updated elapsed time t, the time t is 0 and the offset value C is stored), and the updated elapsed time It is calculated by a method of reading the first deviation value ΔD ₁ corresponding to t. As shown in FIG. 4, in the present embodiment, the first deviation value ΔD ₁ is increased when the elapsed time t after the update increases, but this is temporarily fixed (the path of step S4 and step S5N is continued). In order to prevent the target inter-vehicle distance Dk from continuing and the elapsed time t from becoming too long, the condition is set such that the greater the elapsed time t, the easier it is to make an update determination even if the deviation between Dt and Dk is the same level. . The offset C and the slope are constants set so that the time interval until the next update after setting the target inter-vehicle distance Dk becomes an appropriate level. In step S5, it is determined whether the value of (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) is greater than the first deviation value ΔD _1. If not, the process proceeds to step S6, and if greater, the process proceeds to step S8. In step S6, the target inter-vehicle distance Dk is updated with the calculated appropriate inter-vehicle distance Dv, and the process proceeds to step S7. In step S7, the counter t for measuring the elapsed time from the update of the target inter-vehicle distance Dk is set to 0, and the process proceeds to step S8. In step S8, the control amounts of the throttle actuator 7, the brake actuator 8, etc. are calculated, and the process proceeds to step S9. In step S9, a control amount signal is output to the throttle actuator 7, the brake actuator 8, etc., and this process ends. The second deviation value ΔD ₂ is set to be a numerical value larger than the first deviation value ΔD ₁ .
[0011]
By the above processing, at the stage where the inter-vehicle distance control is started, the basic operation of the inter-vehicle distance control (control using the appropriate inter-vehicle distance Dv based on the vehicle speed as the target inter-vehicle distance Dk) is performed. Next, when the inter-vehicle distance with the preceding vehicle is reduced and the difference between the actual inter-vehicle distance Dt and the target inter-vehicle distance Dk becomes the second deviation value ΔD ₂ , the operation is switched to the inter-vehicle distance control operation using the first deviation value ΔD _1. It is done. When this operation is switched, the value of the appropriate inter-vehicle distance Dv when the operation is switched is used as the target inter-vehicle distance Dk, and the target inter-vehicle distance Dk is fixed until the update of the target inter-vehicle distance Dk described below. Can be used. At the same time, the elapsed time counter t is reset. Thereafter, a determination operation for updating the target inter-vehicle distance Dk is performed using the first deviation value ΔD ₁ based on the counter t. When the difference between the actual inter-vehicle distance Dt and the target inter-vehicle distance Dk reaches the first deviation value ΔD ₁ (obtained in FIG. 4) during the update determination operation, the target inter-vehicle distance Dk is determined as the appropriate inter-vehicle distance Dv based on the current vehicle speed. Is updated to the value of. Based on the target inter-vehicle distance Dk set and updated in this way, the difference between the actual inter-vehicle distance Dt and the target inter-vehicle distance Dk is determined, and acceleration / deceleration control of the vehicle speed, which is a basic operation of inter-vehicle distance control, is performed. . Note that the time counter t is reset at the time of updating. In this way, the actual inter-vehicle distance Dt approaches the target inter-vehicle distance Dk and converges to the inter-vehicle distance corresponding to the vehicle speed.
[0012]
The situation will now be described with reference to FIG.
FIG. 3 is a transition diagram of the vehicle speed V and the inter-vehicle distance D. The vertical axis indicates the vehicle speed V and the inter-vehicle distance D, and the horizontal axis indicates the elapsed time t, and the change state of the vehicle speed V and the inter-vehicle distance D by the inter-vehicle distance control is shown. In this figure, Dt is the current actual inter-vehicle distance, Dk is the target inter-vehicle distance, Dv is the appropriate inter-vehicle distance according to the current vehicle speed, ΔD ₁ is the first deviation value, and ΔD ₂ is the second deviation value.
[0013]
At time 0 in FIG. 3, the basic inter-vehicle distance control operation is performed with the appropriate inter-vehicle distance Dv (step S1) based on the vehicle speed as the target inter-vehicle distance Dk, and the actual inter-vehicle distance while decelerating the vehicle speed over time. The distance Dt is gradually brought closer to the target inter-vehicle distance Dk. Even if time elapses, as long as (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) is larger than the second deviation value ΔD ₂ (step S2), the basic inter-vehicle distance control operation is continued.
[0014]
Next, time t _A is the time when the difference in the inter-vehicle distance (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) has reached the second deviation value ΔD ₂ (determined in step S3). The target inter-vehicle distance Dk is set to an appropriate inter-vehicle distance Dv corresponding to the vehicle speed at time t _A (the route of step S4 and step S5Y). Subsequently, even if the actual inter-vehicle distance Dt decreases with the passage of time, the elapsed time t ₁ until the difference in inter-vehicle distance (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) reaches the first deviation value ΔD ₁ (step S4). During this time, the target inter-vehicle distance Dk is fixed and held at the value set at the time t _A during the elapsed time t ₁ (routes in steps S4 and S5Y).
[0015]
Next, time t _B is the time when the difference in the inter-vehicle distance (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) reaches ΔD ₁₁ (first deviation value ΔD ₁ ) (determined in step S5), At this time, the target inter-vehicle distance Dk is set / updated to an appropriate inter-vehicle distance Dv corresponding to the vehicle speed at time t _B (step S6). This target inter-vehicle distance Dk (the value of the appropriate inter-vehicle distance Dv at time t _B ) reaches time t _C after the subsequent time t _2, and the difference in inter-vehicle distance (actual inter-vehicle distance Dt−target inter-vehicle distance Dk). Is fixedly used until it reaches ΔD ₁₂ (first deviation value ΔD ₁ ) (time t _C ). Thereafter, the update of the target inter-vehicle distance Dk is repeated in the same manner.
[0016]
As described above, when the difference in the inter-vehicle distance (actual inter-vehicle distance Dt−target inter-vehicle distance Dk) is equal to or smaller than the second deviation value ΔD ₂ (variable depending on the relative speed), the target inter-vehicle distance Dk is fixed and the period for fixing is also set. Since the difference in the inter-vehicle distance is set to a period greater than or equal to the first deviation value ΔD ₁ and the basic operation of inter-vehicle distance control is performed based on the target inter-vehicle distance Dk, the target inter-vehicle distance Dt is reduced while the vehicle speed is reduced over time. Compared to the conventional case where the vehicle distance can be converged to the distance Dk and the final distance is controlled with the appropriate distance between vehicles Dv corresponding to the vehicle speed, the vehicle speed control amount does not act excessively, and the vehicle speed increases or decreases due to the vehicle speed control. Is avoided.
[0017]
【The invention's effect】
As described above in detail, according to the inter-vehicle distance control device according to the present invention, it is possible to avoid deterioration in riding comfort due to a fluctuating change in the vehicle speed control amount after the inter-vehicle distance becomes close to the target value.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an inter-vehicle distance control device according to an embodiment of the present invention.
FIG. 2 is a flowchart of processing performed by a control unit 6;
FIG. 3 is a transition diagram of a vehicle speed V and an inter-vehicle distance D.
FIG. 4 is a characteristic diagram of an updated time t and a first deviation value ΔD ₁ .
FIG. 5 is a characteristic diagram of a relative speed Vr and a second deviation value ΔD ₂ .
FIG. 6 is a characteristic diagram of a vehicle speed V and an appropriate inter-vehicle distance Dv.
FIG. 7 is a transition diagram of a vehicle speed V and an inter-vehicle distance D in conventional control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Radar apparatus 2 ... Vehicle speed sensor 3 ... Accelerator switch 4 ... Coast switch 5 ... Set switch 6 ... Microcomputer 7 ... Throttle actuator 8 ... Brake actuator

Claims

Constant speed travel control means for controlling the vehicle travel actuator so that the actual vehicle speed maintains the target vehicle speed;
An inter-vehicle distance detecting means for detecting an inter-vehicle distance between the host vehicle and a preceding vehicle;
In the inter-vehicle distance control device having inter-vehicle distance control means for controlling the travel actuator of the vehicle such that the inter-vehicle distance detected by the inter-vehicle distance detection means becomes the target inter-vehicle distance.
Target inter-vehicle distance setting means for setting the target inter-vehicle distance according to the actual vehicle speed;
Deviation detection means for detecting a deviation between the target inter-vehicle distance set by the target inter-vehicle distance setting means and the actual inter-vehicle distance detected by the inter-vehicle distance detection means;
First starting means for causing the target inter-vehicle distance setting means to perform the setting operation of the target inter-vehicle distance when the deviation detected by the deviation detecting means is equal to or less than a first predetermined value;
Time measuring means for measuring a time after the first starting means performs the setting operation of the target inter-vehicle distance;
An inter-vehicle distance control device comprising: a first predetermined value setting unit that sets the first predetermined value to a value corresponding to the time detected by the time measuring unit.

Constant speed travel control means for controlling the vehicle travel actuator so that the actual vehicle speed maintains the target vehicle speed;
An inter-vehicle distance detecting means for detecting an inter-vehicle distance between the host vehicle and a preceding vehicle;
In the inter-vehicle distance control device having inter-vehicle distance control means for controlling the travel actuator of the vehicle such that the inter-vehicle distance detected by the inter-vehicle distance detection means becomes the target inter-vehicle distance.
Target inter-vehicle distance setting means for setting the target inter-vehicle distance according to the actual vehicle speed;
Deviation detection means for detecting a deviation between the target inter-vehicle distance set by the target inter-vehicle distance setting means and the actual inter-vehicle distance detected by the inter-vehicle distance detection means;
First starting means for causing the target inter-vehicle distance setting means to perform the setting operation of the target inter-vehicle distance when the deviation detected by the deviation detecting means is equal to or less than a first predetermined value;
And a second starting means for causing the target inter-vehicle distance setting means to perform the setting operation of the target inter-vehicle distance when the deviation detected by the deviation detecting means becomes equal to or greater than a second predetermined value greater than the first predetermined value. Inter-vehicle distance control device characterized by

A relative speed detecting means for detecting the relative speed of the host vehicle and the preceding vehicle;
Inter-vehicle distance control apparatus according to claim 2, wherein a and a second predetermined value setting means for setting the second predetermined value to a value corresponding to the relative velocity the relative velocity detecting means detects