JP3733914B2 - Vehicle object detection device, vehicle safety control method, automobile - Google Patents

Description

【００２５】
受信側では、それぞれの送信周波数における受信信号を、アナログ回路２１で分離復調し、それぞれの送信周波数に対する受信信号をＡ／Ｄコンバータ２２でＡ／Ｄ変換する。Ａ／Ｄ変換で得られたディジタルのサンプルデータをＦＦＴ処理部２３で高速フーリエ変換処理し、受信されたビート信号の全周波数帯域での周波数スペクトラムを得る。ＦＦＴ処理の結果得られたピーク信号に対し、２周波ＣＷ方式の原理に基づいて、図３（ｂ）に示すような送信周波数ｆ₁ と送信周波数ｆ₂ のそれぞれに対するピーク信号のパワースペクトルを計測し、２つのパワースペクトルの位相差φから距離(range）を次式で算出する。
【００２６】
【数２】

【００２７】
次に、方向の計測について図８を用いて説明する。図８は、角度に対する各受信アンテナの受信電力パターンを示している。図８に示すように、受信アンテナ１７（ａ）および受信アンテナ１７（ｂ）は、それぞれθが０方向で受信電力が最大となる。受信アンテナ１７（ａ）と１７（ｂ）に入力された信号の和信号（Psum）と差信号(Pdiff）が算出される。受信アンテナ１７（ａ）と１７（ｂ）のアンテナパターンは一定であることから、受信信号の電力の比率から方位角θを特定できる。例えば、サンプリング周波数Ｆ_s ＝５０［Ｈｚ］で２０４８点のデータに対してＦＦＴを施した場合、検出物体の相対速度や位置情報は約４４ｍｓ間隔で計測される。よって従来手法では、相対速度の算出に少なくとも２点必要なので４４ｍｓ以上必要となるが、本実施例によると同時刻(計算時間のみ)で相対速度を算出できる。
【００２８】
上記ＦＦＴ処理の結果、得られたピーク信号に対して信号処理を施し、Δｔ［ｓ］後の物体の位置を予測する例についての処理フローを図４に示す。
【００２９】
図５（ａ）のようにレーダ装置３４を車体前方に取付けた自車３５が、車３３を検出する例において、送信周波数ｆ₁ に対するピーク信号のパワースペクトル３７を図５（ｂ）に示す。これは、検出した車の反射波に対してＦＦＴ処理を行った結果であり、送信周波数ｆ₂ に対するピーク信号のパワースペクトル３６も同様に得られる。これらピーク信号を検出し、その周波数より、数式１と数式２を用いて車の相対速度や距離を算出することができる。つまり、レーダ装置は少なくとも距離情報と相対速度情報とを出力することとなる。自車のレーダを基準とし、検出した車の各点での速度（自車との相対速度）が違うと、その速度分布が周波数軸に対して図５（ｂ）のように表れる。よって、まずステップ２６において、信号強度が所定値以上のピーク値を算出する。従来手法では複数点のデータをグルーピングする際に、例えば電波を車幅分スキャニングするのにＴ［ｓ］かかるとすると、その間に時速１００［km］で走行中の車は１００Ｔ［ｍ］進んでしまうため、各点の検出距離は、少なくとも（１００Ｔ−１００）ｍの誤差を含む。しかし、上記方法により同時刻で複数点における計測を行うことができるので精度が向上する。
【００３０】
ステップ２７へ進み、検出した各ピーク値に対して相対速度，距離，角度の計算を行う。ここで、レーダを原点とし、自車の進行方向をｙ軸とした座標系において、時刻ｔに検出した各位置の座標を（ｘ_i(ｔ)，ｙ_i(ｔ)）とする。検出した位置座標は、検出した物体の各点までの距離ｒ_i(ｔ)，角度θ_i(ｔ)とすると、次式で表現できる。
【００３１】
【数３】
ｘ_i(ｔ)＝ｒ_i(ｔ)sinθ_i(ｔ)
ｙ_i(ｔ)＝ｒ_i(ｔ)cosθ_i(ｔ)
また、ここで検出されたｋ［個］の位置情報をｘ座標とｙ座標それぞれで平均して求めた値を車の位置を表す代表点（Ｘ(ｔ)，Ｙ(ｔ)）とする。Ｘ(ｔ)とＹ(ｔ)は、次式で算出できる。
【００３２】
【数４】

【００３３】
次に、ステップ２８へ進み、検出した車の速度を算出する。車の速度Ｖは、時刻（ｔ−Δｔ）で算出した車の位置（Ｘ（ｔ−Δｔ），Ｙ（ｔ−Δｔ））と、時刻(ｔ)で算出した車の位置（Ｘ(ｔ)，Ｙ(ｔ)）を用いて、次式で算出する。
【００３４】
【数５】

【００３５】
次に、ステップ２９へ進み、検出した車の各点のΔｔ［ｓ］後の位置を算出する。Δｔ［ｓ］後における、車の各点の位置（ｘ_i(ｔ＋Δｔ)，ｙ_i(ｔ＋Δｔ)）は、自車を原点とするとそれぞれ次式で算出できる。
【００３６】
【数６】
ｘ_i（ｔ＋Δｔ）＝（ｒ_i(ｔ)−ＶΔｔ）sinθ_i(ｔ)
ｙ_i（ｔ＋Δｔ）＝（ｒ_i(ｔ)−ＶΔｔ）cosθ_i(ｔ)
以上のステップにより、検出した車の一点のみではなく、複数点の位置情報を算出することで、車の位置変化を細かく予測できる。
【００３７】
次に、上記予測した車の進路と、自車の進路より、両者が衝突するか否かを判断し、その結果にともなって、衝突回避制御や安全装置の作動制御を行う一実施例について、図６，図７を用いて説明する。衝突回避制御を行う装置や安全装置については後述する。
【００３８】
上記Δｔ［ｓ］後の自車の位置を予測し、その結果にともなって、衝突回避制御や安全装置の作動制御を実行する例についての処理フローを図６に示す。
【００３９】
ステップ３０において、Δｔ［ｓ］後の自車位置を算出する。自車速度検出部２で検出された自車速度情報をＶ_h［ｍ／ｓ］ とし、ヨーレート検出部３で検出されたヨーレート情報をω［rad／ｓ］ とすると、自車の進路となるカーブ半径Ｒは次式で求められる。
【００４０】
【数７】
Ｒ＝Ｖ_h／ω
よって、図７に示すような自車と車の横方向距離Ｈ_c および縦方向距離Ｈ_d は、次式で算出される。
【００４１】
【数８】

【００４２】
よって、時刻ｔでのレーダ中心を原点とすると、Δｔ［ｓ］後の自車位置は、

と表される。
【００４３】
同様にして、数式７および数式８を用いて、自車の前方左右の位置も求める。
Δｔ［ｓ］後における自車の左前方の位置座標(Ｘ_left(ｔ＋Δｔ)，Ｙ_left(ｔ＋Δｔ))は、次式で表される。
【００４４】
【数９】

【００４５】
同様に、Δｔ［sec］後における自車の右前方の位置座標（Ｘ_right(ｔ＋Δｔ)，Ｙ_right（ｔ＋Δｔ））は、次式で表される。
【００４６】
【数１０】

【００４７】
ステップ３１へ進み、Δｔ［ｓ］後における、自車と検出した車の各点における距離をそれぞれ算出する。数式７，数式８，数式９，数式１０で算出した自車位置

、自車左前（Ｘ_left(ｔ＋Δｔ)，Ｙ_left(ｔ＋Δｔ)），自車右前（Ｘ_right(ｔ＋Δｔ），Ｙ_right(ｔ＋Δｔ)）と、検出された物体の各点（(ｒ_i(ｔ)−ＶΔｔ）sinθ_i(ｔ)，（ｒ_i(ｔ)−ＶΔｔ）cosθ_i(ｔ)）との距離をそれぞれ計算することにより求められ、それらｊ［個］の各距離をＤ_j とする。
【００４８】
さらに、ステップ３２において、自車と物体との距離が最短となる場所において、その距離Ｄ＝０となる時間ｔを算出する。例えば、図７の例において、自車の左前と、検出した車の代表点（（ｒ₁(ｔ)−ＶΔｔ）sinθ₁(ｔ)，（ｒ₁(ｔ)−ＶΔｔ）cosθ₁(ｔ)）の距離が最も短いと判定された場合、下記の式が成り立つようなｔを求める。
【００４９】
【数１１】
((ｒ₁−ＶΔｔ)sinθ₁−Ｘ_left(ｔ＋Δｔ))²＋((ｒ₁−ＶΔｔ)cosθ₁−Ｙ_left(ｔ＋Δｔ))²＝０
次に、自車と物体が衝突するまでの時間ｔが求められた後に、ステップ３８において、数式１１で算出された時間ｔが所定値Ｔ_c よりも小さいかどうかの判定を行う。ｔが大きい場合は、自車と検出した物体が接近するまでの時間が長いことを意味し、ステップ４１へ進み、衝突する可能性は低いと判断して制御部７において、何も行わないようにする。
【００５０】
時間ｔが所定値Ｔ_c よりも短い場合、衝突の可能性が高いと判断し、ステップ３９へ進む。衝突の可能性がある場合に、自車速度Ｖ_h と物体の速度Ｖが所定値Ｖ_c よりも大きい場合は特に危険である。よって、次式が成り立つ場合にはステップ４０へ進み、衝突回避装置及び安全装置の両方を作動させるような制御を行う。
【００５１】
【数１２】
Ｖ_h＋Ｖ≧Ｖ_c
また、ステップ３９において、数式１２が成り立たない場合には、衝突回避装置のみを作動させる制御を行う。
【００５２】
ここで、衝突回避装置とは、例えば警報装置やブレーキ，スロットル，変速機などを意味する。よって、衝突を事前に検知した場合、警報を鳴らしたり、衝突する速度を低減させるために四輪独立に自動ブレーキをかけたり、自動でステアリング操作を行ったりするための制御を行う。自動ブレーキは、車両がどの方向から衝突してくるかにより、衝突してもできるだけ乗員の安全が確保される場所に衝突させるように四輪ブレーキのかけ方を制御することもできる。例えば、ドライバが１人で右側ハンドル車を運転している場合に、前方に迫る被検物体をドライバのいない助手席側に衝突させるように、右側前後輪のブレーキを左側よりも強くかけて車両を右方に旋回させるといったことが考えられる。自動ステアリングは、検出した車両が衝突してくる方向を算出することにより、障害物が無い方向へ自車が移動するような制御をすることができる。また、自動ステアリングは、検出した車両が衝突してくる方向と衝突する自車の場所を算出することにより、衝突してもできるだけ乗員の安全が確保される場所に衝突できるように制御することもできる。
【００５３】
また、安全装置とは、例えばエアバッグやシートベルトがあり、それらの制御を行う。エアバッグは、衝突する時間を算出することで、できるだけ早めに展開できるような制御を行うこともできる。また、検出した車両が衝突する方向によって、展開するエアバッグ（例えばサイドエアバッグ）も選択できるような制御を行う。シートベルトは、衝突時間を予測することにより、作動させるタイミングを算出し、その算出結果に基づいて制御する。
【００５４】
実施例では物体検出装置として、２周波ＣＷ方式のミリ波レーダを例にして説明したが、他の方式のミリ波レーダや光レーダにも適用できる。他の方式のミリ波レーダを用いる場合には、距離分解能が高いといったメリットがある。一方、光レーダを用いる場合には、空間分解能が高く、距離精度が良いといったメリットがある。また、この実施例では、近距離用のレーダ装置に関して衝突を検知するシステムについて説明したが、近距離のみではなく、例えば１２０ｍまで検知可能なレーダ装置と兼用することによって、車間距離制御システムにも適用できる。其の場合には、１つのセンサで遠距離と近距離の両方を高分解能に検知できるといったメリットがある。また、検知距離を例えば３０ｍまで可能なレーダ装置と兼用することで、比較的車間距離が狭い場合において前方車両の検知が可能となり、自動発進や自動停止機能付きの車間距離制御システム（stop＆goが可能なＡＣＣシステム）にも適用することができる。其の場合には、一般道でのACC機能も備えるといったメリットがある。
【００５５】
【発明の効果】
本発明では、物体を検出する際に、物体の各点からの電磁波に基づいて、被検物体の進路や移動速度や相対的姿勢変化を正確に予測できる物体の進路予測を可能とした。また、この予測結果を基に、衝突回避制御や安全装置の作動制御を実行することで安全性を高めることができる。
【図面の簡単な説明】
【図１】物体の進路予測装置と衝突回避に関する制御装置を備えた一例を表したブロック図である。
【図２】物体の進路予測装置の構成の一例を表した図である。
【図３】レーダ装置の原理を示した図である。
【図４】物体の進路を予測する処理を示したフローチャートの一例である。
【図５】物体の進路を予測する原理の一例を示した図である。
【図６】衝突回避装置と安全装置の作動を制御する処理を示したフローチャートの一例である。
【図７】自車と車の進路を予測する一例を表した図である。
【図８】角度に対する各受信アンテナの受信電力パターンを示した図である。
【符号の説明】
１…物体検出部、２…自車速度検出部、３…ヨーレート検出部、４…物体動き予測部、５…自車動き予測部、６…衝突時間推定部、７…制御部、８…警報装置制御部、９…エアバッグ制御部、１０…シートベルト制御部、１１…ブレーキ制御部、１２…スロットル制御部、１３…変速機制御部、１４…車速センサ、１５…ジャイロ、１６…送信アンテナ、１７…受信アンテナ、１８…発振器、１９…変調器、２０…ミキサ回路、２１…アナログ回路、２２…Ａ／Ｄコンバータ、２３…ＦＦＴ処理部、２４…信号処理部、２５…マイコン、３３…車、３４…レーダ装置、３５…自車、３６…送信周波数ｆ₂ に対するパワースペクトル、３７…送信周波数ｆ₁ に対するパワースペクトル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to detecting the position and relative speed of an object existing around the host vehicle and predicting the course of the object viewed from the host vehicle. The present invention also relates to safety control for preventing collision between the object and the host vehicle.
[0002]
[Prior art]
Conventionally, as an inter-vehicle distance measuring device for automobiles, radio waves are emitted and reflected waves are received from objects such as cars and obstacles, and the propagation time of radio waves, the strength of reflected waves, the Doppler shift of frequency, etc. are detected. Radar devices that measure the distance to an object from the results have been developed.
[0003]
For example, in the description of JP-A-8-124080, a plurality of electromagnetic wave beams are transmitted and a reflected wave is received to detect a vehicle or an obstacle. According to this technology, distance information (a plurality of distance information) between the host vehicle and a plurality of detection points is output from the radar device, and a plurality of detection point data (distance information) is grasped as one group (grouping). The group is detected as a vehicle or an obstacle. Further, the speed of the detected object is calculated by taking the time series change of the distance information, that is, the time differentiation, and the course is predicted.
[0004]
[Problems to be solved by the invention]
In order to prevent vehicle collisions, it is possible to control driving by detecting preceding vehicles and obstacles with radar devices mounted on automobiles, or to detect collisions in advance and use airbags, seat belts, etc. A method for controlling the occupant protection means is conceivable, but in any case, it is desirable to accurately detect the position of an object such as a preceding vehicle or an obstacle to clearly determine whether or not the vehicle is an obstacle. .
[0005]
However, in the above prior art, the radar device outputs distance information of the vehicle and the obstacle (that is, the test object), and it is difficult to accurately predict the movement and moving speed of the test object itself.
[0006]
For example, when position information of a plurality of points of the test object is detected, even if the relative speed of each point with respect to the host vehicle is calculated by taking time differentiation,
First, at the first point and the last point of the grouped range, the plurality of detection point data is not information at the same time, and secondly, unless two points of the same point are taken, Since it is not possible to calculate the relative speed with respect to the host vehicle, calculation time for at least the sampling period will be required.
The actual behavior of the test object and the predicted behavior of the test object cannot be matched in principle, and it is possible to calculate the point closest to the host vehicle, It was difficult to predict.
[0007]
An object of the present invention is to provide an object course prediction apparatus that can solve such problems and can predict the behavior and moving speed of an object to be examined more accurately than before and in a shorter time than before.
[0008]
Moreover, it aims at providing the safety control method regarding the collision of a motor vehicle.
[0009]
Furthermore, it aims at providing the motor vehicle which performs collision avoidance control or operation control of a safety device.
[0010]
[Means for Solving the Problems]
The present invention receives a reflected wave from an object by radiating a radio wave, measures the relative speed, distance, and angle of a plurality of points of a single object from a plurality of peak values of the power spectrum of the reflected wave. By calculating the position information of each of the plurality of points from the relative speed, distance, and angle of the plurality of points of one object, and calculating the velocity vectors of the plurality of points from the temporal displacement and speed information of the position information, respectively. It is an object detection device for a vehicle that predicts behavior including posture change of the single object .
[0011]
Further, the present invention receives a reflected wave from an object by radiating a radio wave, measures the relative speed, distance, and angle of a plurality of points of a single object from a plurality of peak values of the power spectrum of the reflected wave, Calculating the position information of each of the plurality of points from the relative speed, distance, and angle of a plurality of points of a single object, and calculating the velocity vectors of the plurality of points from the temporal displacement and speed information of the position information. Predicting the behavior including the posture change of the single object, and based on the position information of the representative point of the object and the position information of the own vehicle, the temporal change of the relative positional relationship between the object and the own vehicle is calculated. A vehicle object detection device or a safety control method that predicts and executes collision avoidance control of the host vehicle based on the prediction result.
[0012]
Preferably, a time until the object and the vehicle collide is determined based on the position information of the vehicle and the point having the shortest distance from the vehicle among the plurality of points of the object, and the collision of the vehicle based on the time It is to execute avoidance control.
[0013]
The present invention also measures means for receiving a reflected wave from an object by radiating radio waves, and measuring the relative speed, distance, and angle of a plurality of points of a single object from a plurality of peak values of the power spectrum of the reflected wave. And calculating position information of each of the plurality of points from the relative speed, distance and angle of the plurality of points of the single object, and calculating the velocity vector of the plurality of points from the temporal displacement and speed information of the position information. A means for predicting a behavior including a change in posture of the single object by calculating each, a course of the object is obtained from the predicted movement of the object, and a collision of the own vehicle is obtained from the course and position information of the own vehicle. Means for executing avoidance control.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment will be described with reference to FIG. 1 to FIG. 8 taking automobile collision detection as an example.
[0015]
FIG. 1 shows the configuration of an embodiment of the present invention. In this embodiment, a system for detecting a collision will be described in relation to a radar apparatus for a short distance, for example, a detection distance of 5 m.
[0016]
For example, when the speed difference between the host vehicle and the object to be detected is 60 km / h, 5 m (detection distance) is converted to 300 ms. Therefore, when performing control such as detecting collisions in advance and using the results to avoid collisions or to make collisions with little damage, information from the object to be detected is obtained, and the behavior of the vehicle appears / completes. It is required that the time until this is done within 300 ms. If the speed of the preceding vehicle is low or the speed of the oncoming vehicle is high and the speed difference between the subject vehicle and the test object increases, the detection time and control time are further shortened to shorten the overall time. Is required.
[0017]
The object detection unit 1 is required to detect a plurality of points in as short a time as possible. Further, by recognizing the detected posture change including the speed and rotation of the vehicle, it is possible to calculate how fast and in which direction the vehicle collides with the host vehicle. In FIG. 1, a radar device (hereinafter referred to as a radar device) that can calculate the relative speed and position of a plurality of points of an object is used for the object detection unit 1.
[0018]
Further, the vehicle speed sensor 14 in FIG. 2 corresponds to the own vehicle speed detection unit 2 in FIG. 1, and the gyro 15 in FIG. 2 corresponds to the yaw rate detection unit 3 in FIG. In FIG. 1, the object motion prediction unit 4, the own vehicle motion prediction unit 5, and the collision time estimation unit 6 are realized by the microcomputer 25 in FIG.
[0019]
First, an example in which each position information of an object to be detected is calculated based on electromagnetic waves from each point of the object detected by the radar apparatus and a course is predicted will be described.
[0020]
The output of the radar device is distance information, relative speed information, and angle information (information relating to a collision direction). A method of measuring relative speed and distance by the radar apparatus will be described with reference to FIG. The antenna section is composed of a transmission antenna 16 and a reception antenna 17, and a millimeter-wave band high-frequency signal (30 G to 300 GHz) transmitted from the oscillator 18 at a transmission frequency based on the modulation signal from the modulator 19 is transmitted from the transmission antenna 16. Radiated. A radio wave signal that has been reflected back from a reflector such as a car or an object along the road is received by the receiving antenna 17 and subjected to frequency conversion by the mixer circuit 20. The mixer circuit 20 is also supplied with a signal from the oscillator 18, and a low-frequency signal generated by mixing the two signals is output to the analog circuit 21.
[0021]
The signal amplified and output by the analog circuit 21 is converted into a digital signal by the A / D converter 22 and supplied to the FFT processing unit 23. The FFT processing unit 23 measures the frequency spectrum of the signal as amplitude and phase information by Fast Fourier Transform and sends it to the signal processing unit. The distance and relative speed are calculated by the signal processing unit 24 from the data in the frequency domain obtained by the FFT processing unit 23, and are output as a distance measurement value and a relative speed measurement value.
[0022]
Here, the relative speed of the vehicle ahead is measured using the Doppler shift, and the two-frequency CW (Continuous Wave) that measures the distance to the vehicle ahead from the phase information of the received signal at each frequency by switching the two frequencies. ) Type millimeter wave radar will be described with reference to FIGS.
[0023]
In the case of a two-frequency CW-type millimeter wave radar, a modulation signal is input to the oscillator 18 and transmitted while switching the _two frequencies f ₁ and f ₂ as shown in FIG. The radio wave transmitted from the transmitting antenna 16 is reflected by the vehicle ahead, and the reflected signal is received by the receiving antenna 17 (a) and the receiving antenna 17 (b). The received signal and the signal of the oscillator 18 are multiplied by the mixer circuit 20 to obtain a beat signal thereof. In the case of the homodyne system for direct conversion to baseband, the beat signal output from the mixer circuit 20 becomes the Doppler frequency f _d and is calculated by the following equation.
[0024]
[Expression 1]

[0025]
On the reception side, the reception signals at the respective transmission frequencies are separated and demodulated by the analog circuit 21, and the reception signals corresponding to the respective transmission frequencies are A / D converted by the A / D converter 22. The digital sample data obtained by the A / D conversion is subjected to a fast Fourier transform process by the FFT processing unit 23 to obtain a frequency spectrum in the entire frequency band of the received beat signal. For the peak signal obtained as a result of the FFT processing, the power spectrum of the peak signal for each of the transmission frequency f ₁ and the transmission frequency f ₂ as shown in FIG. Then, the range is calculated from the phase difference φ between the two power spectra by the following equation.
[0026]
[Expression 2]

[0027]
Next, direction measurement will be described with reference to FIG. FIG. 8 shows the received power pattern of each receiving antenna with respect to the angle. As shown in FIG. 8, the reception antenna 17 (a) and the reception antenna 17 (b) each have the maximum reception power when θ is in the 0 direction. A sum signal (Psum) and a difference signal (Pdiff) of signals input to the receiving antennas 17 (a) and 17 (b) are calculated. Since the antenna patterns of the receiving antennas 17 (a) and 17 (b) are constant, the azimuth angle θ can be specified from the ratio of the received signal power. For example, when FFT is performed on 2048 points of data at a sampling frequency F _s = 50 [Hz], the relative speed and position information of the detected object are measured at intervals of about 44 ms. Therefore, in the conventional method, since at least two points are required for calculating the relative speed, 44 ms or more is required. However, according to this embodiment, the relative speed can be calculated at the same time (only the calculation time).
[0028]
FIG. 4 shows a processing flow for an example in which signal processing is performed on the peak signal obtained as a result of the FFT processing and the position of the object after Δt [s] is predicted.
[0029]
FIG. 5B shows a power spectrum 37 of the peak signal with respect to the transmission frequency f ₁ in the example in which the own vehicle 35 with the radar device 34 attached to the front of the vehicle body detects the vehicle 33 as shown in FIG. This is a result of performing the FFT processing on the detected reflected wave of the car, and the power spectrum 36 of the peak signal with respect to the transmission frequency f ₂ is obtained similarly. These peak signals are detected, and the relative speed and distance of the vehicle can be calculated from the frequency using Equations 1 and 2. That is, the radar apparatus outputs at least distance information and relative speed information. If the speed at each point of the detected vehicle (relative speed with respect to the own vehicle) is different with reference to the radar of the own vehicle, the speed distribution appears as shown in FIG. 5B with respect to the frequency axis. Therefore, first, in step 26, a peak value having a signal intensity equal to or higher than a predetermined value is calculated. In the conventional method, when grouping data of a plurality of points, for example, if it takes T [s] to scan the radio wave by the vehicle width, the vehicle traveling at 100 [km] per hour during that time advances by 100 T [m]. Therefore, the detection distance of each point includes an error of at least (100T-100) m. However, the accuracy can be improved because measurement at a plurality of points can be performed at the same time by the above method.
[0030]
Proceeding to step 27, the relative speed, distance, and angle are calculated for each detected peak value. Here, in the coordinate system in which the radar is the origin and the traveling direction of the host vehicle is the y-axis, the coordinates of each position detected at time t are (x _i (t), y _i (t)). The detected position coordinates can be expressed by the following equation, assuming that the distance r _i (t) to each point of the detected object and the angle θ _i (t).
[0031]
[Equation 3]
x _i (t) = r _i (t) sin θ _i (t)
y _i (t) = r _i (t) cos θ _i (t)
In addition, a value obtained by averaging the detected k [pieces] position information in each of the x coordinate and the y coordinate is set as a representative point (X (t), Y (t)) representing the position of the car. X (t) and Y (t) can be calculated by the following equations.
[0032]
[Expression 4]

[0033]
Next, the process proceeds to step 28, and the detected vehicle speed is calculated. The vehicle speed V includes the vehicle position (X (t−Δt), Y (t−Δt)) calculated at time (t−Δt) and the vehicle position (X (t)) calculated at time (t). , Y (t)), the following equation is used.
[0034]
[Equation 5]

[0035]
Next, the process proceeds to step 29, and the position after Δt [s] of each point of the detected car is calculated. The position (x _i (t + Δt), y _i (t + Δt)) of each point of the vehicle after Δt [s] can be calculated by the following equations, respectively, where the vehicle is the origin.
[0036]
[Formula 6]
x _i (t + Δt) = (r _i (t) −VΔt) sin θ _i (t)
y _i (t + Δt) = (r _i (t) −VΔt) cos θ _i (t)
By calculating the position information of a plurality of points instead of only one point of the detected vehicle, the position change of the vehicle can be predicted in detail by the above steps.
[0037]
Next, from the predicted course of the vehicle and the course of the own vehicle, it is determined whether or not both collide, and according to the result, the collision avoidance control and the safety device operation control are performed. This will be described with reference to FIGS. A device for performing collision avoidance control and a safety device will be described later.
[0038]
FIG. 6 shows a processing flow for an example in which the position of the host vehicle after Δt [s] is predicted and collision avoidance control and safety device operation control are executed according to the result.
[0039]
In step 30, the vehicle position after Δt [s] is calculated. When the own vehicle speed information detected by the own vehicle speed detection unit 2 is V _h [m / s] and the yaw rate information detected by the yaw rate detection unit 3 is ω [rad / s], the course of the own vehicle is obtained. The curve radius R is obtained by the following equation.
[0040]
[Expression 7]
R = V _h / ω
Accordingly, the lateral distance H _c and the longitudinal distance H _d between the host vehicle and the vehicle as shown in FIG. 7 are calculated by the following equations.
[0041]
[Equation 8]

[0042]
Therefore, if the radar center at time t is the origin, the vehicle position after Δt [s] is

It is expressed.
[0043]
Similarly, using Formula 7 and Formula 8, the front left and right positions of the host vehicle are also obtained.
Position coordinates (X _left (t + Δt), Y _left (t + Δt)) of the left front of the vehicle after Δt [s] are expressed by the following equations.
[0044]
[Equation 9]

[0045]
Similarly, the position coordinates (X _right (t + Δt), Y _right (t + Δt)) ahead of the vehicle after Δt [sec] are expressed by the following equations.
[0046]
[Expression 10]

[0047]
Proceeding to step 31, the distance at each point of the detected vehicle and the vehicle after Δt [s] is calculated. The vehicle position calculated by Equation 7, Equation 8, Equation 9, and Equation 10.

The left front of the host vehicle (X _left (t + Δt), Y _left (t + Δt)), the front right of the host vehicle (X _right (t + Δt), Y _right (t + Δt)), and each point of the detected object ((r _i (t) _{-VΔt) sinθ i (t),} (r i (t) is determined by calculating the respective distances between the _{-VΔt) cosθ i (t))} , the respective distances they j [piece] and D _j.
[0048]
Further, in step 32, a time t at which the distance D = 0 is calculated at the place where the distance between the own vehicle and the object is the shortest. For example, in the example of FIG. 7, the left front of the host vehicle and the representative point of the detected vehicle ((r ₁ (t) −VΔt) sinθ ₁ (t), (r ₁ (t) −VΔt) cosθ ₁ (t) ) Is determined to be such that the following formula is satisfied.
[0049]
[Expression 11]
((r ₁ −VΔt) sin θ ₁ −X _left (t + Δt)) ² + ((r ₁ −VΔt) cos θ ₁ −Y _left (t + Δt)) ² = 0
Next, after the time t until the vehicle and the object collide is obtained, in step 38, it is determined whether or not the time t calculated by Expression 11 is smaller than a predetermined value _Tc . If t is large, it means that it takes a long time for the vehicle and the detected object to approach, and the process proceeds to step 41 where it is determined that the possibility of collision is low and nothing is performed in the control unit 7. To.
[0050]
If the time t is shorter than the predetermined value T _c , it is determined that the possibility of collision is high, and the process proceeds to step 39. When there is a possibility of collision, it is particularly dangerous when the vehicle speed V _h and the object speed V are larger than a predetermined value V _c . Therefore, when the following equation is established, the process proceeds to step 40, and control is performed so as to operate both the collision avoidance device and the safety device.
[0051]
[Expression 12]
V _h + V ≧ V _c
In step 39, if Equation 12 does not hold, control is performed to operate only the collision avoidance device.
[0052]
Here, the collision avoidance device means, for example, an alarm device, a brake, a throttle, a transmission, or the like. Therefore, when a collision is detected in advance, an alarm is sounded, an automatic brake is independently applied to reduce the collision speed, and control for automatically performing a steering operation is performed. The automatic brake can also control how the four-wheel brake is applied so that the vehicle can collide with a place where the safety of the occupant is ensured as much as possible depending on the direction from which the vehicle collides. For example, when the driver is driving a right-hand drive vehicle alone, the vehicle should be braked on the right front and rear wheels more strongly than the left side so that the test object approaching forward collides with the passenger seat side without the driver. It is possible to turn the to the right. The automatic steering can be controlled such that the vehicle moves in a direction in which there is no obstacle by calculating the direction in which the detected vehicle collides. In addition, the automatic steering can be controlled so that it can collide with a place where the safety of the occupant is ensured as much as possible even by the collision by calculating the direction of the vehicle that collides with the detected vehicle. it can.
[0053]
The safety device includes, for example, an air bag and a seat belt, and controls them. The airbag can be controlled so that it can be deployed as early as possible by calculating the collision time. Further, control is performed such that an airbag to be deployed (for example, a side airbag) can be selected depending on the direction in which the detected vehicle collides. The seat belt calculates the timing to operate by predicting the collision time, and controls based on the calculation result.
[0054]
In the embodiment, the two-frequency CW type millimeter wave radar has been described as an example of the object detection device. However, the present invention can also be applied to other types of millimeter wave radars and optical radars. When using another type of millimeter wave radar, there is an advantage that the distance resolution is high. On the other hand, when an optical radar is used, there are advantages such as high spatial resolution and good distance accuracy. In this embodiment, a system for detecting a collision with respect to a short-distance radar apparatus has been described. However, not only a short-distance radar apparatus but also a radar apparatus capable of detecting up to 120 m, for example, can be used for an inter-vehicle distance control system. Applicable. In that case, there is a merit that both a long distance and a short distance can be detected with high resolution by one sensor. In addition, by combining with a radar device that can detect distances up to 30m, for example, it is possible to detect a forward vehicle when the distance between vehicles is relatively small, and an inter-vehicle distance control system with automatic start and automatic stop functions (stop & go is possible) The present invention can also be applied to other ACC systems. In that case, there is a merit of having an ACC function on a general road.
[0055]
【The invention's effect】
In the present invention, when detecting an object, it is possible to predict the path of an object that can accurately predict the path, moving speed, and relative posture change of the object to be detected based on electromagnetic waves from each point of the object. Further, safety can be improved by executing collision avoidance control and safety device operation control based on the prediction result.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example including an object course prediction apparatus and a control apparatus related to collision avoidance.
FIG. 2 is a diagram illustrating an example of a configuration of an object course prediction apparatus.
FIG. 3 is a diagram illustrating the principle of a radar apparatus.
FIG. 4 is an example of a flowchart showing a process for predicting the course of an object.
FIG. 5 is a diagram showing an example of a principle for predicting the course of an object.
FIG. 6 is an example of a flowchart showing a process for controlling the operation of the collision avoidance device and the safety device.
FIG. 7 is a diagram illustrating an example of predicting the course of the vehicle and the vehicle.
FIG. 8 is a diagram showing a received power pattern of each receiving antenna with respect to an angle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Object detection part, 2 ... Own vehicle speed detection part, 3 ... Yaw rate detection part, 4 ... Object motion estimation part, 5 ... Own vehicle motion prediction part, 6 ... Collision time estimation part, 7 ... Control part, 8 ... Alarm Device control unit, 9 ... airbag control unit, 10 ... seat belt control unit, 11 ... brake control unit, 12 ... throttle control unit, 13 ... transmission control unit, 14 ... vehicle speed sensor, 15 ... gyro, 16 ... transmission antenna , 17: receiving antenna, 18 ... oscillator, 19 ... modulator, 20 ... mixer circuit, 21 ... analog circuit, 22 ... A / D converter, 23 ... FFT processing unit, 24 ... signal processing unit, 25 ... microcomputer, 33 ... car, 34 ... radar apparatus, 35 ... vehicle, 36 ... power spectrum with respect to the transmission frequency f _2, 37 ... power spectrum with respect to the transmission frequency f _1.

Claims (8)

Means for emitting radio waves and receiving reflected waves from an object ;
The relative speed of the plurality of points of a single object from a plurality of peak values of the power spectrum of the reflected wave, the distance, and means for measuring the angle meter,
The relative speed of the plurality of points of said single object body, the distance, and while leaving calculate the position information of each of the plurality of points from an angle, a velocity vector of the plurality of points from a temporal displacement and speed information of the location information Means for predicting a behavior including posture change of the single object by calculating each ;
An object detection device for a vehicle having The vehicle object detection device according to claim 1,
Means for predicting the motion of the single object, as well as to predict the course of the previous SL product body from the velocity vector of the plurality of points, to calculate the relative position change of the object from a change in velocity vector of the plurality of points that vehicles of the object detection apparatus. The vehicle object detection device according to claim 1 ,
Means for predicting the temporal change in the relative positional relationship between the object and the vehicle based on the position information of the position information and the vehicle of a representative point of the object,
Means for executing at least one of the operation control of the collision avoidance control or safety devices of the vehicle on the basis of the prediction result,
An object detection device for a vehicle having The vehicle object detection device according to claim 1,
Based on the position where the distance from the vehicle is the shortest among the plurality of points of the object and the position information of the vehicle, the time until the object and the vehicle collide is obtained, and the collision avoidance control of the vehicle is performed based on the time. A vehicle object detection device to be executed. Radiate radio waves and receive reflected waves from objects,
Measure the relative speed, distance, and angle of multiple points of a single object from multiple peak values of the power spectrum of the reflected wave,
The position information of each of the plurality of points is calculated from the relative speed, distance, and angle of the plurality of points of the single object, and the velocity vectors of the plurality of points are calculated from the temporal displacement and speed information of the position information. Predicting the behavior including the posture change of the single object,
Predicting a temporal change in the relative positional relationship between the object and the vehicle based on the position information of the representative point of the object and the position information of the vehicle;
A vehicle safety control method for executing collision avoidance control of a host vehicle based on the prediction result. A vehicle safety control method according to claim 5,
A vehicle safety control method that predicts a course of the object from the plurality of velocity vectors and calculates a relative posture change of the object from a change in the plurality of velocity vectors. A vehicle safety control method according to claim 5,
Based on the position where the distance from the vehicle is the shortest among the plurality of points of the object and the position information of the vehicle, the time until the object and the vehicle collide is obtained, and the collision avoidance control of the vehicle is performed based on the time. A vehicle safety control method to be executed. Means for emitting radio waves and receiving reflected waves from an object ;
The relative speed of the plurality of points of a single object from a plurality of peak values of the power spectrum of the reflected wave, the distance, and means for measuring the angle meter,
The relative speed of the plurality of points of said single object body, the distance, and calculates the position information of each of the plurality of points from an angle, from the time displacement and speed information of the location information the velocity vector of the plurality of points respectively Means for predicting a behavior including a change in posture of the single object by calculating;
Seeking the path of the object from the motion of the predicted object, and means for executing a collision avoidance control of the vehicle based on the position information of the route and the vehicle,
A motor vehicle having a.

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