JP2004114896A - Driving operation assisting device for vehicle, driving operation assisting method for vehicle, and vehicle employing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving operation assisting device for a vehicle capable of reducing troublesomeness given to a driver by reaction control, and quickly transmitting information to the driver when risk potential need be informed. <P>SOLUTION: This driving operation assisting device 1 for a vehicle comprises driving environment detecting means 10 and 20 to detect driving environments around the vehicle, a risk potential determining means 50 to determine risk potential of the vehicle based on driving environments detected by the driving environments detecting means 10 and 20, a reaction control means 60 to control operation reaction generated when the driver operates a vehicle device 62 in accordance with the risk potential determined by the risk potential determining means 50, and a reaction control starting threshold setting means 50 to set a threshold of the risk potential to start reaction control by the reaction control means 60. <P>COPYRIGHT: (C)2004,JPO

Description

（式４）
図９に、時間軸に対するリスクポテンシャル変化率ΔＲＰの変化の一例を示す。
【００２４】
ステップＳ１０６では、ステップＳ１０５で算出したリスクポテンシャル変化率ΔＲＰに基づいて、反力制御しきい値ＲＰを変更し、新たな反力制御しきい値ＲＰ０’を設定する。反力制御しきい値ＲＰ０’は、例えば以下の（式５）のように、予め設定した反力制御しきい値ＲＰ０に係数ｋを積算することによって設定できる。
【数５】
ＲＰ０’＝ｋ×ＲＰ０　　　　（ｋ≦１）　　　　（式５）
【００２５】
図１０に、リスクポテンシャル変化率ΔＲＰと係数ｋとの関係の一例を示す。図１０に示すように、リスクポテンシャル変化率ΔＲＰが所定値ΔＲＰ１以上、すなわちリスクポテンシャルＲＰが変化率ΔＲＰ１以上で増加する場合には、変化率ΔＲＰが大きくなるほど係数ｋが小さくなる。また、リスクポテンシャル変化率ΔＲＰが所定値ΔＲＰ１未満の場合には、係数ｋ＝１に設定する。これにより、リスクポテンシャルＲＰが変化率ΔＲＰ１以上で増加する場合には、反力制御しきい値ＲＰ０’が、所定のしきい値ＲＰ０よりも小さくなるよう設定される。一方、変化率ΔＲＰが小さい場合およびリスクポテンシャルＲＰが低下する場合は、係数ｋ＝１であるので、反力制御しきい値ＲＰ０’＝ＲＰ０に設定される。
【００２６】
ステップＳ１０７では、ステップＳ１０２で算出したリスクポテンシャルＲＰが、ステップＳ１０６で設定した反力制御しきい値ＲＰ０’を上回るか否かを判定する。ステップＳ１０７が肯定判定されると、ステップＳ１０８へ進んでアクセルペダル反力制御マップを補正する。具体的には、図１１のリスクポテンシャル−反力増加量特性に示すように、リスクポテンシャルＲＰがＲＰ０’からＲＰ０の領域では、反力増加量ΔＦをリスクポテンシャルＲＰ０に対応する反力増加量ΔＦ０に設定する。なお、ステップＳ１０７が否定判定されると、アクセルペダル反力制御マップを変更しない。
【００２７】
ステップＳ１０９では、ステップＳ１０２で算出されたリスクポテンシャルＲＰに応じて、図３あるいは図１１に示す反力制御マップに従って反力増加量ΔＦを算出する。続くステップＳ１１０で、ステップＳ１０９で算出した反力増加量ΔＦをアクセルペダル反力制御装置６０へ出力し、今回の処理を終了する。
【００２８】
このように、以上説明した第１の実施の形態においては、以下のような効果を奏することができる。
（１）アクセルペダル反力制御を開始するリスクポテンシャルＲＰのレベル、すなわち反力制御開始しきい値ＲＰ０を可変で設定するので、運転者に与える煩わしさを低減するとともに、リスクポテンシャルＲＰを知らせる必要がある場合には迅速に運転者に情報を伝達することができる。
（２）リスクポテンシャルの変化率ΔＲＰに基づいて反力制御開始しきい値を設定するので、リスクポテンシャルＲＰを知らせる必要がある場合に迅速に運転者に情報提供をすることができる。
（３）図１０に示すように、リスクポテンシャル変化率ΔＲＰが増加するほど反力制御開始しきい値ＲＰ０が小さくなるように設定するので、リスクポテンシャルＲＰが確実に所定レベル以上になる場合にはより早いタイミングで運転者に情報を提供することができる。
（４）リスクポテンシャル変化率ΔＲＰの算出方法をリスクポテンシャルＲＰに応じて設定する。具体的には、現時点までに算出されたリスクポテンシャルの変化率の平均値をリスクポテンシャル変化率ΔＲＰとして算出し、変化率ΔＲＰ算出の際に用いるリスクポテンシャルのデータ個数を現在のリスクポテンシャルに応じて変更する。これにより、現時点までのリスクポテンシャルの変化状況に応じて変化率ΔＲＰを算出し、これをアクセルペダル反力制御に反映してより確実な反力制御を行うことができる。
（５）リスクポテンシャル変化率ΔＲＰを算出する際に、図８に示すようにリスクポテンシャルＲＰが大きくなるほど使用データ個数を少なくするので、反力制御しきい値ＲＰ０以下でリスクポテンシャルＲＰが大きい場合には、算出されたリスクポテンシャルの感度を重視して反力制御開始のタイミングを決定することができる。一方、リスクポテンシャルＲＰが小さい場合には使用データ個数を多くするので、算出されたリスクポテンシャルの安定性を重視して運転者に煩わしさを与えないように反力制御開始のタイミングを決定することができる。
【００２９】
《第２の実施の形態》
つぎに、本発明の第２の実施の形態による車両用運転操作補助装置について説明する。第２の実施の形態による車両用運転操作補助装置の構成は、図１および図２に示した第１の実施の形態と同様であるので、その説明を省略する。ここでは、第１の実施の形態との相違点を主に説明する。
【００３０】
第２の実施の形態においては、現在までに算出したリスクポテンシャルＲＰに基づいて将来のリスクポテンシャルＲＰｅおよびリスクポテンシャル変化率ΔＲＰｅを予測し、これらに基づいて反力制御開始しきい値ＲＰ０を変更する。
【００３１】
第２の実施の形態における反力制御開始しきい値ＲＰ０の設定およびアクセルペダル反力制御について、図１２を用いて説明する。図１２は、第２の実施の形態によるコントローラ５０における運転操作補助制御処理の処理手順を示すフローチャートである。本処理内容は、一定間隔、例えば５０ｍｓｅｃ毎に連続的に行われる。
【００３２】
ステップＳ２０１〜Ｓ２０３での処理は、上述した図６のフローチャートのステップＳ１０１〜Ｓ１０３での処理と同様である。
【００３３】
ステップＳ２０４では、反力制御開始しきい値ＲＰ０の変更に利用する将来のリスクポテンシャル変化率ΔＲＰｅを算出するための算出方法を設定する。具体的には、上述した第１の実施の形態と同様に、変化率ΔＲＰｅを算出するために用いるデータ個数ｎを設定する。さらに、どの時間領域のリスクポテンシャルデータを用いるか、すなわち使用データのうちの予測リスクポテンシャルＲＰｅの割合についても設定する。使用データ個数ｎは、図８に示したように、ステップＳ２０２で算出したリスクポテンシャルＲＰに応じて設定する。予測リスクポテンシャルＲＰｅの割合は、使用データ個数ｎは変更せずにデータを算出する時間軸をスライドし、予測リスクポテンシャル変化率ΔＲＰｅの比重μとして設定する。図１３に、所定のサンプリング周期毎に算出されるリスクポテンシャルＲＰおよび将来の予測リスクポテンシャルＲＰｅと、使用データ個数ｎと予測リスクポテンシャル変化率ΔＲＰｅの比重μとの関係を模式的に示す。
【００３４】
図１４に、リスクポテンシャルＲＰと予測リスクポテンシャル変化率ΔＲＰｅの比重μとの関係の一例を示す。図１４に示すように、リスクポテンシャルＲＰが所定値ＲＰｃ以下の領域では、比重μを最小値μ０に設定し、所定値ＲＰｃから所定値ＲＰｄの間の領域では、リスクポテンシャルＲＰが大きくなるほど比重μを大きくする。また、所定値ＲＰｄ以上の領域では、最大値μｍに設定する。このように、リスクポテンシャルＲＰが小さい場合には、予測リスクポテンシャルＲＰｅの個数を少なくし、すなわち過去のリスクポテンシャルデータを多く用いて確実な予測リスクポテンシャル変化率ΔＲＰｅを算出する。一方、リスクポテンシャルＲＰが大きい場合には、予測リスクポテンシャルＲＰｅの個数を多くし、より早いタイミングで反力制御を開始するようにする。
【００３５】
ステップＳ２０５では、ステップＳ２０４で設定した使用データ個数ｎおよび予測リスクポテンシャル変化率の比重μに従って、予測リスクポテンシャル変化率ΔＲＰｅを算出する。予測リスクポテンシャル変化率ΔＲＰｅを算出するために、まず予測リスクポテンシャルＲＰｅを算出する。将来予測されるリスクポテンシャルＲＰｅ（ｔ＋１）は、以下の（式６）に示すように、現時点ｔおよびそれ以前の時点（ｔ−１）、（ｔ−２）におけるリスクポテンシャルＲＰ（ｔ）、ＲＰ（ｔ−１）、ＲＰ（ｔ−２）を用いて、現時点ｔを中心としてテイラー展開を行うことにより算出することができる。
【数６】
ＲＰｅ（ｔ＋１）＝ＲＰ（ｔ）＋｛（ＲＰ（ｔ）−ＲＰ（ｔ−１）｝＋１／２｛ＲＰ（ｔ）−ＲＰ（ｔ−１）｝−１／２｛（ＲＰ（ｔ−１）−ＲＰ（ｔ−２）｝　　　　　　　　　　　　　　　　　　　　　　　　（式６）
【００３６】
使用データ個数ｎおよび比重μに応じて（式６）の時間軸をスライドし、必要な個数の予測リスクポテンシャルＲＰｅを算出する。
【００３７】
そして、上述した（式１）により、予測リスクポテンシャル変化率ΔＲＰｅを算出する。
【００３８】
ステップＳ２０６では、上述した図６のフローチャートのステップＳ１０６と同様に、図１０に従って係数ｋを算出し、（式５）より反力制御しきい値ＲＰ０’を設定する。これ以降のステップＳ２０７〜Ｓ２１０での処理は、上述した図６のステップＳ１０７〜Ｓ１１０と同様である。
【００３９】
このように、以上説明した第２の実施の形態においては、以下のような効果を奏することができる。
（１）現時点までの走行環境に基づいて将来のリスクポテンシャルＲＰｅを予測し、さらに、将来の予測リスクポテンシャル変化率ΔＲＰｅを算出する。予測リスクポテンシャル変化率ΔＲＰｅに基づいて反力制御開始しきい値ＲＰ０を設定するので、リスクポテンシャルＲＰを運転者に伝達する必要がある場合には迅速に情報を提供することができる。なお、予測されるリスクポテンシャル変化率ΔＲＰｅを用いて反力制御開始しきい値ＲＰ０を設定するので、第１の実施の形態に比べてより早い段階で反力制御開始のタイミングを決定することができる。
（２）予測リスクポテンシャル変化率ΔＲＰｅが増加するほど反力制御開始しきい値ＲＰ０が小さくなるように設定するので、リスクポテンシャルＲＰが確実に所定レベル以上になる場合にはより早いタイミングで運転者に情報を提供することができる。
（３）予測リスクポテンシャル変化率ΔＲＰｅの算出方法をリスクポテンシャルＲＰに応じて設定する。具体的には、現時点までに算出されたリスクポテンシャルおよび予測されたリスクポテンシャルＲＰｅの変化率の平均値を、予測リスクポテンシャル変化率ΔＲＰｅとして算出し、予測変化率ΔＲＰｅ算出の際に用いるリスクポテンシャルＲＰおよび予測リスクポテンシャルＲＰｅのデータ個数を現在のリスクポテンシャルＲＰに応じて変更する。これにより、現時点までのリスクポテンシャルＲＰおよび予測リスクポテンシャルＲＰｅの変化状況に応じて予測変化率ΔＲＰｅを算出し、アクセルペダル反力制御開始の判断を早い段階で行うことができる。
（４）予測リスクポテンシャル変化率ΔＲＰｅを算出する際に、図８に示すようにリスクポテンシャルＲＰが大きくなるほど使用データ個数を少なくするので、反力制御しきい値ＲＰ０以下でリスクポテンシャルＲＰが大きい場合には、算出されたリスクポテンシャルの感度を重視して反力制御開始のタイミングを決定することができる。一方、リスクポテンシャルＲＰが小さい場合には使用データ個数を多くするので、算出されたリスクポテンシャルの安定性を重視して運転者に煩わしさを与えないように反力制御開始のタイミングを決定することができる。
【００４０】
上記実施の形態においては、設定した反力制御開始しきい値ＲＰ０’に応じて、図１１に示すようにリスクポテンシャル−反力増加量特性を変更したが、変更方法はこれには限定されない。例えば、図１１に一点鎖線で示すように、リスクポテンシャルＲＰが所定値ＲＰ０を上回る領域におけるリスクポテンシャル−反力増加量特性を、反力制御開始しきい値ＲＰ０’まで延長することもできる。この場合、しきい値ＲＰ０’以上の領域で、反力増加量ΔＦは指数関数的に増加する。また、破線で示すように、リスクポテンシャルＲＰがＲＰ０’からＲＰ０の領域で反力増加量ΔＦを初期値ΔＦ０までリニアに増加させることもできる。また、リスクポテンシャルＲＰに対する反力増加量ΔＦの特性は、指数関数的に増加することには限定されず、リスクポテンシャルＲＰが大きくなるほど反力増加量ΔＦが増加すれば、例えばリニアに増加するように設定することもできる。
【００４１】
上記第２の実施の形態においては、予測リスクポテンシャル変化率ΔＲＰｅを算出し、これに基づいて反力制御開始しきい値ＲＰ０’を設定したが、本発明はこれには限定されない。例えば、算出した将来の予測リスクポテンシャルＲＰｅが予め設定した反力制御開始しきい値ＲＰ０を超えたら、アクセルペダル反力制御を開始することもできる。この場合、予測リスクポテンシャル変化率ΔＲＰｅを算出する必要がないので、コントローラ５０における処理を簡素化することができる。
【００４２】
上記実施の形態においては、余裕時間ＴＴＣと車間時間ＴＨＷとを用いて障害物に対するリスクポテンシャルＲＰを算出したが、これには限定されない。例えば余裕時間ＴＴＣの逆数をリスクポテンシャルＲＰとして用いることができる。また、車両周囲に存在する複数の障害物に対する余裕時間ＴＴＣを算出し、各障害物に対する余裕時間ＴＴＣの逆数の車両前後方向成分を加算して総合的なリスクポテンシャルＲＰを算出することもできる。
【００４３】
また、リスクポテンシャルＲＰに応じて制御する操作反力はアクセルペダル反力のみには限定されず、例えばブレーキペダル反力あるいは操舵反力をリスクポテンシャルＲＰに応じてそれぞれ制御することもできる。
【００４４】
本発明による車両用運転操作補助方法が適用される車両は、図２に示す構成には限定されない。
【００４５】
以上説明した本発明による車両用運転操作補助装置の一実施の形態においては、走行環境検出手段として、レーザレーダ１０および車速センサ２０を用いた。リスクポテンシャル算出手段と、反力制御開始しきい値設定手段と、リスクポテンシャル変化率算出手段と、変化率算出設定手段と、リスクポテンシャル予測手段と、予測リスクポテンシャル変化率算出手段と、予測変化率算出設定手段として、コントローラ５０を用いた。また、反力制御手段として、アクセルペダル反力制御装置６０およびコントローラ５０を用いた。ただし、本発明による車両用運転操作補助装置は、これらには限定されない。自車両周囲の走行環境を検出することができれば走行環境検出手段として、例えばＣＣＤやＣＭＯＳからなるカメラあるいはミリ波レーダ等を用いることもできる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態による車両用運転操作補助装置のシステム図。
【図２】図１に示す車両用運転操作補助装置を搭載した車両の構成図。
【図３】リスクポテンシャルに対する反力増加量の特性を示す図。
【図４】時間軸に対するリスクポテンシャルの変化の一例を示す図。
【図５】反力制御開始タイミングの変化を示す図。
【図６】第１の実施の形態の車両用運転操作補助装置における運転操作補助制御プログラムの処理手順を示すフローチャート。
【図７】リスクポテンシャルの算出タイミングを示す図。
【図８】リスクポテンシャルと使用データ個数との関係を示す図。
【図９】時間軸に対するリスクポテンシャル変化率の変化の一例を示す図。
【図１０】リスクポテンシャル変化率と係数ｋとの関係を示す図。
【図１１】反力制御開始しきい値変更後のリスクポテンシャルに対する反力属領の特性を示す図。
【図１２】第２の実施の形態の車両用運転操作補助装置における運転操作補助制御プログラムの処理手順を示すフローチャート。
【図１３】リスクポテンシャルの算出タイミングと使用データ個数と予測リスクポテンシャルの比重との関係を示す図。
【図１４】リスクポテンシャルと予測リスクポテンシャルの比重との関係を示す図。
【符号の説明】
１０：レーザレーダ
２０：車速センサ
５０：コントローラ
６０：アクセルペダル反力制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving assist system for a vehicle that assists a driver's operation.
[0002]
[Prior art]
2. Description of the Related Art A conventional vehicle driving assist system detects an inter-vehicle distance to a vehicle in front of the vehicle, and performs an operation reaction force control of an accelerator pedal when the detected inter-vehicle distance is equal to or less than a predetermined value. ). This vehicle driving assist system makes the accelerator pedal operation reaction force variable based on the accelerator pedal operation amount and operation speed.
Prior art documents related to the present invention include the following.
[Patent Document 1]
JP-A-10-166889 [Patent Document 2]
JP-A-10-166890 [0003]
[Problems to be solved by the invention]
However, the vehicle driving assist system as described above sequentially controls the accelerator pedal reaction force based on the driver's pedal operation, and changes in the risk potential around the vehicle to the reaction force control more quickly. It is hoped to reflect.
[0004]
[Means for Solving the Problems]
The driving assist system for a vehicle according to the present invention includes: a driving environment detecting unit that detects a driving environment around the host vehicle; and a risk potential that calculates a risk potential of the host vehicle based on the driving environment detected by the driving environment detecting unit. Calculating means, reaction force control means for controlling an operation reaction force generated when the driver operates the vehicle equipment according to the risk potential calculated by the risk potential calculation means, and reaction force control by the reaction force control means And a reaction force control start threshold value setting means for variably setting the threshold value of the risk potential for starting the control.
[0005]
【The invention's effect】
Since the level of the risk potential for starting the reaction force control is variably set, the troublesomeness given to the driver can be reduced, and the information can be promptly transmitted to the driver when it is necessary to inform the driver of the risk potential. .
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
<< 1st Embodiment >>
A vehicle driving assist system according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing a configuration of a vehicle driving assist system 1 according to a first embodiment of the present invention. FIG. 1 is a configuration diagram of a vehicle to which a driving operation assisting method is applied.
[0007]
First, the configuration of the vehicle driving assist system 1 will be described. The laser radar 10 is attached to a front grill portion or a bumper portion of a vehicle, and scans an infrared light pulse in a horizontal direction. The laser radar 10 measures the reflected wave of the infrared light pulse reflected by a plurality of reflectors ahead (usually, the rear end of the preceding vehicle), and calculates the distance between the plurality of preceding vehicles based on the arrival time of the reflected wave. Detects the distance and the relative speed of the vehicle. The detected inter-vehicle distance and relative vehicle speed are output to the controller 50. The front area scanned by the laser radar 10 is about ± 6 deg with respect to the front of the vehicle, and a front object existing within this range is detected.
[0008]
The vehicle speed sensor 20 detects the traveling vehicle speed of the host vehicle from the number of rotations of the wheels and the like, and outputs the detected traveling speed to the controller 50.
[0009]
The controller 50 is composed of a CPU and CPU peripheral components such as a ROM and a RAM, and controls the entire vehicle driving assist system 1 in a software form of the CPU. The controller 50 calculates a risk potential for an obstacle around the own vehicle based on the own vehicle speed input from the vehicle speed sensor 20 and the distance / vehicle speed information input from the laser radar 10. Further, the controller 50 performs accelerator pedal reaction force control according to the risk potential as described later.
[0010]
The accelerator pedal reaction force control device 60 controls a torque generated by a servomotor 61 incorporated in a link mechanism of the accelerator pedal 62 according to a command from the controller 50. The servo motor 61 controls a reaction force generated in accordance with a command value from the accelerator pedal operation reaction force control device 60, and can arbitrarily control a pedal force generated when the driver operates the accelerator pedal 82. .
[0011]
Next, the operation of the vehicle driving assist system 1 according to the first embodiment will be described. The outline of the operation is described below.
The controller 50 calculates the risk potential RP of the host vehicle based on the running speed of the host vehicle, the relative distance between the host vehicle and the obstacle, and the relative vehicle speed. Then, an accelerator pedal reaction force control amount according to the calculated risk potential RP is calculated. FIG. 3 shows an example of a characteristic of the accelerator pedal reaction force increase amount ΔF with respect to the risk potential RP. As shown in FIG. 3, when the risk potential RP exceeds the predetermined value RP0, the reaction force increase ΔF increases as the risk potential RP increases. In FIG. 3, the reaction force increase amount ΔF is set to increase exponentially with respect to the risk potential RP. The calculated accelerator pedal reaction force control amount ΔF is output to accelerator pedal reaction force control device 60 as a reaction force control command value. The accelerator pedal reaction force control device 60 changes the accelerator pedal reaction force characteristic by controlling the servomotor 61 according to the input reaction force control command value. By changing the accelerator pedal reaction force characteristic, control is performed such that the actual accelerator pedal operation amount of the driver is promoted to an appropriate value.
[0012]
The accelerator pedal reaction force control device 60 changes the accelerator pedal reaction force characteristic by adding the reaction force increase amount ΔF to the normal pedal reaction force characteristic that changes according to the accelerator pedal stroke amount.
[0013]
As shown in FIG. 3, when the risk potential RP is equal to or less than a predetermined value RP0, the reaction force increase amount ΔF = 0, and the pedal reaction force based on the normal reaction force characteristic without adding the reaction force increase amount ΔF to the accelerator pedal 62. Occurs. That is, as can be seen from an example of the change in the risk potential RP with respect to the time axis before and after the start of the accelerator pedal reaction force control shown in FIG. 4, the risk potential RP is generated before the timing t1 when the risk potential RP reaches the predetermined value RP0. However, it does not perform the pedal reaction force control according to it. Thus, it is possible to prevent the operation reaction force of the accelerator pedal from being controlled in a region where the risk potential RP is small, thereby preventing the driver from being bothered.
[0014]
However, as shown in FIG. 4, when the risk potential RP definitely exceeds the predetermined value RP0, it is desirable to start the pedal reaction force control at an earlier timing and to immediately transmit the risk potential RP to the driver. . Therefore, in the first embodiment of the present invention, as shown in FIG. 5, a predetermined value RP0, which is a threshold value for starting the reaction force control, is variably set so that the risk potential RP surely exceeds the predetermined level. , The reaction force control is started at a timing t1a earlier than the timing t1. Specifically, a change rate ΔRP of the risk potential RP is calculated, and a reaction force control start threshold value RP0 is set according to the change rate ΔRP.
[0015]
Hereinafter, the setting of the reaction force control start threshold value RP0 and the accelerator pedal reaction force control according to the first embodiment will be described with reference to FIG. FIG. 6 is a flowchart illustrating a processing procedure of the driving assist control process in the controller 50 according to the first embodiment. This processing content is continuously performed at regular intervals, for example, every 50 msec. Hereinafter, a case where a preceding vehicle is detected as an obstacle around the vehicle will be described as an example.
[0016]
First, the driving environment data is read in step S101. Here, the traveling environment data includes the relative distance D and the relative speed Vr to the preceding vehicle detected by the laser radar 10, the own vehicle speed Vf detected by the vehicle speed sensor 20, and the like.
[0017]
In step S102, a risk potential RP for the preceding vehicle is calculated based on the traveling environment data read in step S101. The risk potential RP for the preceding vehicle can be calculated using the following (Equation 1), for example, based on the time to contact TTC to the preceding vehicle and the inter-vehicle time THW to the preceding vehicle.
(Equation 1)
RP = a / THW + b / TTC (Equation 1)
Here, the constants a and b are parameters for appropriately weighting the inter-vehicle time THW and the allowance time TTC, and are set so that a <b (for example, a = 1 and b = 8).
[0018]
The allowance time TTC is expressed by the following equation (2) using the inter-vehicle distance D to the preceding vehicle and the relative speed Vr, and the inter-vehicle time THW is expressed by the following equation using the inter-vehicle distance D and the own vehicle speed Vf. It is expressed as 3).
(Equation 2)
TTC = D / Vr (Equation 2)
[Equation 3]
THW = D / Vf (Equation 3)
When the own vehicle follows the preceding vehicle, the preceding vehicle speed Va can be used instead of the own vehicle speed Vf in (Equation 3).
[0019]
In step S103, it is determined whether or not the risk potential RP calculated in step S102 exceeds a preset reaction force control start threshold value RP0. If the determination in step S103 is affirmative, the process proceeds to step S109, and the reaction force increase amount ΔF according to the risk potential RP is calculated according to FIG. On the other hand, if a negative determination is made in step S103, the process proceeds to step S104.
[0020]
In step S104, a calculation method for calculating the risk potential change rate ΔRP used for setting (changing) the reaction force control start threshold value RP0 is set. Specifically, the number of data n used for calculating the risk potential change rate ΔRP is set. The risk potential data calculated before this processing is stored in a memory (not shown).
[0021]
FIG. 7 schematically shows the risk potential RP calculated for each predetermined sampling period, and FIG. 8 shows the relationship between the risk potential RP and the number n of data used for calculating the risk potential change rate ΔRP. As shown in FIG. 7, the risk potential RP before the current time t has been increasing with time.
[0022]
As shown in FIG. 8, when the risk potential RP is smaller than the predetermined value RPa, the number n of used data is set to m (that is, the risk potential calculated from time tm to time t). When the risk potential RP is between the predetermined value RPa and the predetermined value RPb (RPa <RPb), the data number n is reduced as the risk potential RP increases, and when the risk potential RP is larger than the predetermined value RPb, the data number n is set to the minimum value mm. I do. As described above, when the risk potential RP is large, the sensitivity of the calculated risk potential RP is emphasized. On the other hand, when the risk potential RP is small, the stability of the risk potential RP, that is, the noise resistance is emphasized, and the rate of change is emphasized. Set ΔRP. In a region where the risk potential RP is equal to or larger than the threshold value RP0, the risk potential change rate ΔRP is calculated using m pieces of data.
[0023]
In step S105, the risk potential change rate ΔRP is calculated using the n pieces of risk potential data set in step S104. The risk potential change rate ΔRP can be calculated by the following (Equation 4).
(Equation 4)

(Equation 4)
FIG. 9 shows an example of a change in the risk potential change rate ΔRP with respect to the time axis.
[0024]
In step S106, the reaction force control threshold value RP is changed based on the risk potential change rate ΔRP calculated in step S105, and a new reaction force control threshold value RP0 ′ is set. The reaction force control threshold value RP0 'can be set, for example, by multiplying a coefficient k to a preset reaction force control threshold value RP0 as shown in the following (Equation 5).
(Equation 5)
RP0 ′ = k × RP0 (k ≦ 1) (Equation 5)
[0025]
FIG. 10 shows an example of the relationship between the risk potential change rate ΔRP and the coefficient k. As shown in FIG. 10, when the risk potential change rate ΔRP is equal to or more than a predetermined value ΔRP1, that is, when the risk potential RP is increased at a change rate ΔRP1 or more, the coefficient k decreases as the change rate ΔRP increases. When the risk potential change rate ΔRP is smaller than the predetermined value ΔRP1, the coefficient k is set to k = 1. Thereby, when the risk potential RP increases at the change rate ΔRP1 or more, the reaction force control threshold value RP0 ′ is set to be smaller than the predetermined threshold value RP0. On the other hand, when the rate of change ΔRP is small and the risk potential RP decreases, the coefficient k = 1, so that the reaction force control threshold value RP0 ′ = RP0.
[0026]
In step S107, it is determined whether or not the risk potential RP calculated in step S102 exceeds the reaction force control threshold value RP0 'set in step S106. If the determination in step S107 is affirmative, the process proceeds to step S108 to correct the accelerator pedal reaction force control map. Specifically, as shown in the risk potential-reaction force increase characteristic of FIG. 11, in the region where the risk potential RP is from RP0 ′ to RP0, the reaction force increase ΔF is set to the reaction force increase ΔF0 corresponding to the risk potential RP0. Set to. If a negative determination is made in step S107, the accelerator pedal reaction force control map is not changed.
[0027]
In step S109, the reaction force increase amount ΔF is calculated according to the reaction force control map shown in FIG. 3 or 11 according to the risk potential RP calculated in step S102. In subsequent step S110, the reaction force increase amount ΔF calculated in step S109 is output to accelerator pedal reaction force control device 60, and the current process ends.
[0028]
As described above, in the first embodiment described above, the following effects can be obtained.
(1) Since the level of the risk potential RP for starting the accelerator pedal reaction force control, that is, the reaction force control start threshold value RP0, is variably set, it is necessary to reduce the troublesomeness given to the driver and to inform the driver of the risk potential RP. If there is, the information can be quickly transmitted to the driver.
(2) Since the reaction force control start threshold value is set based on the risk potential change rate ΔRP, it is possible to promptly provide information to the driver when the risk potential RP needs to be notified.
(3) As shown in FIG. 10, since the reaction force control start threshold value RP0 is set to be smaller as the risk potential change rate ΔRP increases, when the risk potential RP reliably exceeds a predetermined level, Information can be provided to the driver at an earlier timing.
(4) The method of calculating the risk potential change rate ΔRP is set according to the risk potential RP. Specifically, the average value of the change rate of the risk potential calculated up to the present time is calculated as the risk potential change rate ΔRP, and the number of risk potential data used in calculating the change rate ΔRP is determined according to the current risk potential. change. As a result, the rate of change ΔRP is calculated in accordance with the change state of the risk potential up to the present time, and this is reflected in the accelerator pedal reaction force control, whereby more reliable reaction force control can be performed.
(5) When calculating the risk potential change rate ΔRP, as shown in FIG. 8, the larger the risk potential RP is, the smaller the number of data used is. Can determine the timing of starting the reaction force control with emphasis on the sensitivity of the calculated risk potential. On the other hand, when the risk potential RP is small, the number of data to be used is increased. Therefore, the stability of the calculated risk potential is emphasized and the timing of starting the reaction force control is determined so as not to inconvenience the driver. Can be.
[0029]
<< 2nd Embodiment >>
Next, a vehicle driving assist system according to a second embodiment of the present invention will be described. The configuration of the driving assist system for a vehicle according to the second embodiment is the same as that of the first embodiment shown in FIGS. 1 and 2, and therefore the description thereof is omitted. Here, differences from the first embodiment will be mainly described.
[0030]
In the second embodiment, a future risk potential RPe and a risk potential change rate ΔRPe are predicted based on the risk potential RP calculated so far, and the reaction force control start threshold value RP0 is changed based on these. .
[0031]
The setting of the reaction force control start threshold value RP0 and the accelerator pedal reaction force control in the second embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating a processing procedure of a driving assist control process in the controller 50 according to the second embodiment. This processing content is continuously performed at regular intervals, for example, every 50 msec.
[0032]
The processing in steps S201 to S203 is the same as the processing in steps S101 to S103 in the above-described flowchart of FIG.
[0033]
In step S204, a calculation method for calculating a future risk potential change rate ΔRPe used for changing the reaction force control start threshold value RP0 is set. Specifically, similarly to the first embodiment, the number of data n used for calculating the change rate ΔRPe is set. Further, it is also set in which time domain the risk potential data is used, that is, the ratio of the predicted risk potential RPe in the usage data. As shown in FIG. 8, the used data number n is set according to the risk potential RP calculated in step S202. The ratio of the predicted risk potential RPe is set as the specific gravity μ of the predicted risk potential change rate ΔRPe by sliding the time axis for calculating the data without changing the used data number n. FIG. 13 schematically shows the relationship between the risk potential RP calculated in each predetermined sampling cycle and the predicted risk potential RPe in the future, the number n of used data, and the specific gravity μ of the predicted risk potential change rate ΔRPe.
[0034]
FIG. 14 shows an example of the relationship between the risk potential RP and the specific gravity μ of the predicted risk potential change rate ΔRPe. As shown in FIG. 14, in a region where the risk potential RP is equal to or less than the predetermined value RPc, the specific gravity μ is set to the minimum value μ0, and in a region between the predetermined value RPc and the predetermined value RPd, the specific gravity μ increases as the risk potential RP increases. To increase. In a region equal to or larger than the predetermined value RPd, the maximum value is set to μm. As described above, when the risk potential RP is small, the number of predicted risk potentials RPe is reduced, that is, a reliable predicted risk potential change rate ΔRPe is calculated using a large amount of past risk potential data. On the other hand, if the risk potential RP is large, the number of predicted risk potentials RPe is increased, and the reaction force control is started earlier.
[0035]
In step S205, the predicted risk potential change rate ΔRPe is calculated according to the number of used data n and the specific gravity μ of the predicted risk potential change rate set in step S204. To calculate the predicted risk potential change rate ΔRPe, first, the predicted risk potential RPe is calculated. As shown in the following (Equation 6), the risk potential RPe (t + 1) predicted in the future is the risk potential RP (t), RP (t), RP (t) at the current time t and before (t−1), (t−2). It can be calculated by performing Taylor expansion centering on the present time t using (t-1) and RP (t-2).
(Equation 6)
RPe (t + 1) = RP (t) + {(RP (t) -RP (t-1)} + 1/2 {RP (t) -RP (t-1)}-1/2} (RP (t- 1) -RP (t-2)｝ (Equation 6)
[0036]
The time axis of (Equation 6) is slid according to the used data number n and the specific gravity μ to calculate the required number of predicted risk potentials RPe.
[0037]
Then, the predicted risk potential change rate ΔRPe is calculated by the above (Equation 1).
[0038]
In step S206, the coefficient k is calculated according to FIG. 10 and the reaction force control threshold value RP0 ′ is set according to (Equation 5), similarly to step S106 in the flowchart of FIG. 6 described above. Subsequent processes in steps S207 to S210 are the same as steps S107 to S110 in FIG. 6 described above.
[0039]
Thus, the following effects can be obtained in the second embodiment described above.
(1) A future risk potential RPe is predicted based on the driving environment up to the present time, and a future predicted risk potential change rate ΔRPe is calculated. Since the reaction force control start threshold value RP0 is set based on the predicted risk potential change rate ΔRPe, when the risk potential RP needs to be transmitted to the driver, information can be promptly provided. Since the reaction force control start threshold value RP0 is set using the predicted risk potential change rate ΔRPe, the reaction force control start timing can be determined earlier than in the first embodiment. it can.
(2) Since the reaction force control start threshold value RP0 is set to be smaller as the predicted risk potential change rate ΔRPe increases, if the risk potential RP surely exceeds a predetermined level, the driver is set earlier. Information can be provided to
(3) The method of calculating the predicted risk potential change rate ΔRPe is set according to the risk potential RP. Specifically, the average value of the change rates of the risk potential calculated up to the present time and the predicted risk potential RPe is calculated as the predicted risk potential change rate ΔRPe, and the risk potential RP used in calculating the predicted change rate ΔRPe is calculated. And the data number of the predicted risk potential RPe is changed according to the current risk potential RP. Thus, it is possible to calculate the predicted change rate ΔRPe in accordance with the change state of the risk potential RP and the predicted risk potential RPe up to the present time, and determine the start of the accelerator pedal reaction force control at an early stage.
(4) When calculating the predicted risk potential change rate ΔRPe, as shown in FIG. 8, since the number of data used decreases as the risk potential RP increases, the risk potential RP is less than the reaction force control threshold value RP0. In this case, the timing of starting the reaction force control can be determined with emphasis on the sensitivity of the calculated risk potential. On the other hand, when the risk potential RP is small, the number of data to be used is increased. Therefore, the stability of the calculated risk potential is emphasized and the timing of starting the reaction force control is determined so as not to inconvenience the driver. Can be.
[0040]
In the above embodiment, the risk potential-reaction force increase amount characteristic is changed as shown in FIG. 11 according to the set reaction force control start threshold value RP0 ′, but the change method is not limited to this. For example, as shown by a dashed line in FIG. 11, the risk potential-reaction force increase amount characteristic in a region where the risk potential RP exceeds the predetermined value RP0 can be extended to the reaction force control start threshold value RP0 '. In this case, the reaction force increase amount ΔF increases exponentially in a region equal to or larger than the threshold value RP0 ′. Further, as indicated by the broken line, the reaction force increase amount ΔF can be linearly increased from the risk potential RP to the initial value ΔF0 in the region from RP0 ′ to RP0. Further, the characteristic of the reaction force increase amount ΔF with respect to the risk potential RP is not limited to an exponential increase. If the reaction force increase amount ΔF increases as the risk potential RP increases, for example, the characteristic increases linearly. Can also be set to
[0041]
In the second embodiment, the predicted risk potential change rate ΔRPe is calculated, and the reaction force control start threshold value RP0 ′ is set based on the calculated risk potential change rate ΔRPe. However, the present invention is not limited to this. For example, when the calculated future predicted risk potential RPe exceeds a preset reaction force control start threshold value RP0, the accelerator pedal reaction force control can be started. In this case, it is not necessary to calculate the predicted risk potential change rate ΔRPe, so that the processing in the controller 50 can be simplified.
[0042]
In the above embodiment, the risk potential RP for the obstacle is calculated using the time to contact TTC and the time to headway THW, but the present invention is not limited to this. For example, the reciprocal of the time to contact TTC can be used as the risk potential RP. It is also possible to calculate the total risk potential RP by calculating the allowance time TTC for a plurality of obstacles existing around the vehicle and adding the reciprocal of the allowance time TTC for each obstacle in the vehicle longitudinal direction component.
[0043]
The operation reaction force controlled in accordance with the risk potential RP is not limited to only the accelerator pedal reaction force. For example, the brake pedal reaction force or the steering reaction force can be controlled in accordance with the risk potential RP.
[0044]
The vehicle to which the vehicle driving assist method according to the present invention is applied is not limited to the configuration shown in FIG.
[0045]
In the embodiment of the vehicle driving assist system according to the present invention described above, the laser radar 10 and the vehicle speed sensor 20 are used as the traveling environment detecting means. Risk potential calculation means, reaction force control start threshold setting means, risk potential change rate calculation means, change rate calculation setting means, risk potential prediction means, predicted risk potential change rate calculation means, predicted change rate The controller 50 was used as the calculation setting means. Further, an accelerator pedal reaction force control device 60 and a controller 50 were used as reaction force control means. However, the vehicle driving assist system according to the present invention is not limited to these. As long as the traveling environment around the own vehicle can be detected, as the traveling environment detecting means, for example, a camera composed of CCD or CMOS, a millimeter wave radar, or the like can be used.
[Brief description of the drawings]
FIG. 1 is a system diagram of a vehicle driving assist system according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a vehicle equipped with the vehicle driving assist system shown in FIG.
FIG. 3 is a diagram showing characteristics of a reaction force increase amount with respect to a risk potential.
FIG. 4 is a diagram showing an example of a change in risk potential with respect to a time axis.
FIG. 5 is a diagram showing a change in a reaction force control start timing.
FIG. 6 is a flowchart illustrating a processing procedure of a driving operation assist control program in the vehicle driving operation assist device according to the first embodiment;
FIG. 7 is a diagram showing a calculation timing of a risk potential.
FIG. 8 is a diagram showing a relationship between a risk potential and the number of used data.
FIG. 9 is a diagram showing an example of a change in a risk potential change rate with respect to a time axis.
FIG. 10 is a diagram showing a relationship between a risk potential change rate and a coefficient k.
FIG. 11 is a view showing characteristics of a reaction force territory with respect to a risk potential after a reaction force control start threshold value is changed.
FIG. 12 is a flowchart illustrating a processing procedure of a driving assist control program in the driving assist device for a vehicle according to the second embodiment;
FIG. 13 is a diagram showing the relationship between the calculation timing of the risk potential, the number of used data, and the specific gravity of the predicted risk potential.
FIG. 14 is a diagram showing a relationship between a risk potential and a specific gravity of a predicted risk potential.
[Explanation of symbols]
10: laser radar 20: vehicle speed sensor 50: controller 60: accelerator pedal reaction force control device

Claims (15)

Driving environment detecting means for detecting a driving environment around the own vehicle;
Risk potential calculation means for calculating the risk potential of the vehicle based on the driving environment detected by the driving environment detection means,
Reaction force control means for controlling an operation reaction force generated when the driver operates the vehicle equipment, according to the risk potential calculated by the risk potential calculation means,
Reaction force control threshold value setting means for variably setting a threshold value of a risk potential (hereinafter referred to as a reaction force control start threshold value) for starting the reaction force control by the reaction force control means. Driving operation assisting device for vehicles. The vehicle driving assist system according to claim 1,
Further comprising a risk potential change rate calculating means for calculating the change rate of the risk potential,
The reaction force control start threshold value setting means sets the reaction force control start threshold value based on the risk potential change rate calculated by the risk potential change rate calculation means. Operation assistance device. The vehicle driving assist system according to claim 2,
The driving force assisting device for a vehicle, wherein the reaction force control start threshold value setting means sets the reaction force control start threshold value to decrease as the risk potential change rate increases. The vehicle driving assist device according to claim 2 or 3,
A driving operation assisting device for a vehicle, further comprising a change rate calculation setting means for setting a method of calculating a risk potential change rate by the risk potential change rate calculation means according to the risk potential. The vehicle driving assist device according to claim 4,
The risk potential change rate calculating means calculates an average value of a plurality of risk potential change rates calculated up to the present time by the risk potential calculating means as the risk potential change rate,
The change rate calculation setting means sets the risk potential change rate calculation method by changing the number of data of the risk potential used in calculating the risk potential change rate according to the risk potential at the present time. A driving assistance device for a vehicle, comprising: The vehicle driving assist system according to claim 5,
The driving-operation assisting device for a vehicle, wherein the change rate calculation setting unit reduces the number of data as the risk potential increases below the reaction force control start threshold value. The vehicle driving assist system according to claim 1,
Risk potential prediction means for predicting a future risk potential (hereinafter referred to as a predicted risk potential) based on the driving environment up to the present time detected by the driving environment detection means;
Predicted risk potential change rate calculating means for calculating a future risk potential change rate (hereinafter referred to as predicted risk potential change rate) using the predicted risk potential and the risk potential calculated by the risk potential calculating means; Further having
The vehicle, wherein the reaction force control start threshold value setting means sets the reaction force control start threshold value based on the predicted risk potential change rate calculated by the predicted risk potential change rate calculation means. Driving operation assist device. The vehicle driving assist system according to claim 7,
The reaction force control start threshold value setting means sets the reaction force control start threshold value so as to decrease as the predicted risk potential change rate increases. The vehicle driving assist device according to claim 7 or 8,
A driving operation assisting device for a vehicle, further comprising: a predicted change rate calculation setting unit that sets a method of calculating the predicted risk potential change rate by the predicted risk potential change rate calculation unit according to the risk potential. The vehicle driving assist system according to claim 9,
The predicted risk potential change rate calculating means includes at least one risk potential calculated up to the present time by the risk potential calculating means, and at least one predicted risk potential change rate calculated by the predicted risk potential calculating means. The average value is calculated as the predicted risk potential change rate,
The predicted change rate calculation setting means changes the risk potential and the number of data of the predicted risk potential used in calculating the predicted risk potential change rate according to the risk potential at the present time, thereby obtaining the predicted risk potential. A driving assist system for a vehicle, wherein a calculation method of a change rate is set. The vehicle driving assist system according to claim 10,
The driving operation assisting device for a vehicle, wherein the predicted change rate calculation setting means reduces the number of data as the risk potential increases below the reaction force control start threshold value. Driving environment detecting means for detecting a driving environment around the own vehicle;
Risk potential calculation means for calculating the risk potential of the vehicle based on the driving environment detected by the driving environment detection means,
Risk potential prediction means for predicting a future risk potential (hereinafter referred to as a predicted risk potential) based on the driving environment up to the present time detected by the driving environment detection means;
When the predicted risk potential calculated by the risk potential prediction means exceeds a predetermined reaction force control start threshold, when a driver operates a vehicle device in accordance with the risk potential calculated by the risk potential calculation means. And a reaction force control means for controlling an operation reaction force generated in the vehicle. The vehicle driving assist system according to any one of claims 1 to 12,
The driving force assisting device for a vehicle, wherein the reaction force control means controls an operation reaction force generated on an accelerator pedal. Detects the driving environment around the vehicle,
Based on the detected driving environment, calculate the risk potential of the vehicle,
According to the calculated risk potential, control the reaction force generated when the driver operates the vehicle equipment,
A driving assistance method for a vehicle, characterized in that a level of a risk potential for starting a reaction force control of the vehicle device is variably set according to a change in the traveling environment. A vehicle to which the driving operation assisting method according to claim 14 is applied.

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