JP2004143974A - Vehicular travel control device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel control device and a method for improving stability in an environment having small external force or a low speed area, and capable of coping with even an environment having large external force. <P>SOLUTION: A deriving factor (k) of nonlinear control input in sliding control is set to k1 being a maximum value when the size ¾σ¾ of a switching function σ is larger than a predetermined value σ1, and is reduced in proportion to reduction in the size ¾σ¾ of the switching function σ when the size ¾σ¾ of the switching function σ is not more than the predetermined value σ1, and is set to a minimum value k0 when the size ¾σ¾ of the switching function σ is not more than a specified value σ0 (<σ1) smaller than the predetermined value σ1. The factor (k) changing according to the size ¾σ¾ of the switching function σ based on a road surface grade estimate is prestored in a memory in a table form, and the nonlinear control input is derived by reading out a value of the factor (k) according to the size ¾σ¾ of the switching function σ. <P>COPYRIGHT: (C)2004,JPO

Description

【００３６】
一方、スライディングモードによる制御入力ｕは、上記したように、等価制御入力ｕｅｑと、非線形制御入力ｕｎｌとの和（ｕ＝ｕｅｑ＋ｕｎｌ）により表わされる。ここで、本制御系におけるサーボ系の線形状態方程式は数式２のようになり、スライディング制御における切換関数σを、
σ＝Ｓ＊ｘ（但し、Ｓは係数）
として、スライディングモードにおいては、数式３が成立するため、等価制御入力ｕｅｑは、数式４により表わされる。尚、数式２において、ｒは指令加速度Ａ＊　を積分して求めた指令車速、ｄは外乱、ａ，ｂ，ｆはそれぞれ制御対象である車両の運動特性から求まる係数、ｚは指令車速と実車速の偏差の積分値、ｖは車速センサにより検出される自車の実車速であり、ｘはｚとｖから成るベクトルを表わす。
【００３７】
【数２】

【００３８】
【数３】

【００３９】
【数４】

【００４０】
そして、数式４より、等価制御入力ｕｅｑは、切換関数σの係数行列Ｓによって決定され、数式５で表わされるリカッチ方程式の解Ｐを用いて切換行列Ｓを決定することで、安定余裕を指定する手法をとるのが好ましい。
【００４１】
【数５】

【００４２】
次に、非線形制御入力ｕｎｌは、数式６により表わされ、この非線形制御入力ｕｎｌの導出には、上記したように図４に示すように切換関数σの大きさ｜σ｜に応じて変化する係数ｋを用い、低速域及び路面勾配（外力）の小さい環境下でのハンチングを防止するようにしている。尚、数式６で、δは正の数で、チャタリングを防止するための係数であり、ｋは切換関数σの０への収束を実現するための外力（ここでは、路面勾配）の影響やモデル化誤差を考慮して設定される係数である。
【００４３】
【数６】

【００４４】
そして、実験車両により平坦路を追従走行したときの制御結果を図５に示す。この結果は、車速が約１０ｋｍ／ｈの状態から加速した先行車に追従したときのもので、図５から、指令加速度（Ａ＊　）に対して、加速直後及び指令加速度の小さい定常状態のいずれにおいてもオーバーシュート、アンダーシュートが小さく、良好に追従できていることがわかる。一方、比較のために従来のＰＩＤ制御による結果を図６に示すが、このＰＩＤ制御の場合、車両の非線形性に対応できないことから、指令加速度に対してオーバーシュート、アンダーシュートが非常に大きく安定性に欠けていることがわかる。
【００４５】
続いて、上り勾配路及び下り勾配路での制御結果を、図７及び図８にそれぞれ示す。これらの結果は、約７％の勾配路においてほぼ停止状態から加速した先行車に追従したときのもので、図７及び図８から、上り勾配及び下り勾配ともに指令加速度に対してオーバーシュート、アンダーシュートが小さく、良好に追従できていることがわかる。特に、上り勾配路では、外乱オブザーバ１７からの路面勾配推定値Ｅｄによる路面勾配種別（上り勾配）により、制御ゲインが高めに設定されていることに加え、システムの状態が切換平面からから離れて非線形制御入力ｕｎｌが大きくなっていることにより、このような結果になったものと推測される。尚、図８における制御開始直後における実加速度のばたつきは、ブレーキ解除に伴う車両の動きに起因するものである。
【００４６】
このように、スライディングモード制御系の切換関数σの大きさ｜σ｜が所定値σ１より大きい時には最大値ｋ１に、切換関数σの大きさ｜σ｜が所定値σ１より小さい既定値σ０以下では最小値ｋ０に設定され、切換関数σの大きさ｜σ｜がσ１からσ０の間では切換関数σの大きさ｜σ｜の減少に比例して減少するように設定された係数ｋをスライディングコントローラ１５のメモリに格納しておき、路面勾配推定値Ｅｄに基づく切換関数σの大きさ｜σ｜に応じた係数ｋの値がメモリから選択され、非線形制御入力ｕｎｌが導出されて制御入力ｕが演算され、演算される制御入力ｕに基づいて、路面勾配に応じた最適な指令スロットル開度θ＊　を導出されてスロットル開度制御手段が制御される。
【００４７】
従って、上記した実施形態によれば、従来のように、想定し得る最大外力に応じた一義的な非線形制御入力ｕｎｌではなく、切換関数σの大きさ｜σ｜に応じて非線形制御入力ｕｎｌの導出用係数ｋの値をスライディングコントローラ１５のメモリから適宜選択することができ、その結果、スライディングモード理論によるスロットル制御において、路面勾配の小さい環境下或いは低速域で安定した制御を実現することができると共に、路面勾配の大きい環境にも十分対応することができる。
【００４８】
また、係数ｋは、切換関数σの大きさ｜σ｜が所定値σ１より大きい時には最大値ｋ１に、切換関数σの大きさ｜σ｜が所定値σ１より小さい既定値σ０以下では最小値ｋ０に設定され、切換関数σの大きさ｜σ｜がσ１からσ０の間では切換関数σの大きさ｜σ｜の減少に比例して減少するように設定され、しかも係数ｋの最小値ｋ０は、低速域においてハンチングを生じない程度の値に設定され、最大値ｋ１は、想定される最大の路面勾配に基づいて設定されるため、切換関数σの大きさ｜σ｜に応じた係数ｋの値を適宜選択することができる。
【００４９】
更に、車両の状況から路面勾配を推定できるため、路面勾配に応じた最適な指令スロットル開度θ＊　を導出して、安定したスロットル制御を実現することができる。
【００５０】
なお、本発明は上記した実施形態に限定されるものではなく、その趣旨を逸脱しない限りにおいて上述したもの以外に種々の変更を行うことが可能である。
【００５１】
例えば、上記した実施形態では、格納手段としてのメモリをスライディングコントローラ１５に内蔵のＲＯＭ等として説明しているが、外付けのメモリを格納手段としても構わないのは勿論である。
【００５２】
また、上記した実施形態では、本発明をスロットル制御に適用した場合の例を示したが、その他の車両の走行制御にも同様に適用できるのはいうまでもなく、上記した実施形態と同等の効果を得ることできる。
【００５３】
【発明の効果】
以上のように、請求項１，６に記載の発明によれば、切換関数の大きさに応じた係数の値が選択され、非線形制御入力が導出されて制御入力が演算され、演算される制御入力に基づき加減速手段が制御されるため、従来のように、想定し得る最大外力に応じた一義的な非線形制御入力ではなく、切換関数の大きさに応じて非線形制御入力の導出用係数の値を格納手段から適宜選択することができ、その結果、スライディングモード理論による車両の走行制御において、路面勾配等の外力の小さい環境下或いは低速域で安定した制御を実現することができると共に、外力の大きい環境にも十分対応することが可能になる。
【００５４】
また、請求項２，３に記載の発明によれば、切換関数の大きさに応じて非線形制御入力の導出用係数の値を格納手段から適宜選択することができるため、スライディングモード理論による車両の走行制御において、路面勾配等の外力の小さい環境下或いは低速域で安定した制御を実現することが可能になると共に、外力の大きい環境にも十分対応することが可能になる。
【００５５】
また、請求項４に記載の発明によれば、スライディングモード理論によるスロットル制御において、路面勾配等の外力の小さい環境下或いは低速域において、安定したスロットル制御を実現することができると共に、外力の大きい環境にも十分対応して安定したスロットル制御を実現することが可能になる。
【００５６】
また、請求項５に記載の発明によれば、車両の状況から路面勾配を推定できるため、路面勾配に応じた最適な指令スロットル開度を導出して、安定したスロットル制御を実現することが可能になる。
【００５７】
また、請求項７に記載の発明によれば、スライディングモード理論によるスロットル制御において、路面勾配等の外力の小さい環境下或いは低速域において、安定したスロットル制御を実現することができると共に、外力の大きい環境にも十分対応して安定したスロットル制御を実現することが可能になる。
【００５８】
また、請求項８，９に記載の発明によれば、切換関数の大きさに応じて非線形制御入力の導出用係数の値を格納手段から適宜選択することができるため、スライディングモード理論によるスロットル制御において、路面勾配等の外力の小さい環境下或いは低速域で安定したスロットル制御を実現することができると共に、外力の大きい環境にも十分対応して安定したスロットル制御を実現することが可能になる。
【図面の簡単な説明】
【図１】この発明の一実施形態における適用車両の外観斜視図である。
【図２】この発明の一実施形態における制御系のブロック図である。
【図３】図２の一部のブロック図である。
【図４】この発明の一実施形態における動作説明図である。
【図５】この発明の一実施形態における動作説明図である。
【図６】この発明の一実施形態における動作説明図である。
【図７】この発明の一実施形態における動作説明図である。
【図８】この発明の一実施形態における動作説明図である。
【図９】この発明の背景となるスライディング制御の説明図である。
【符号の説明】
３　　　レーザレーダ（車間距離センサ、スロットル開度制御手段）
９　　　車間距離コントローラ（指令加速度導出手段、スロットル開度制御手段）
１５　　スライディングコントローラ（制御入力演算手段、指令スロットル開度導出手段、制御手段、スロットル開度制御手段）
１７　　外乱オブザーバ（推定手段、スロットル開度制御手段）
１７１　指令スロットル開度入力・車速出力モデル（車速推定値導出手段）
１７３　外力入力・車速出力モデルの逆モデル（勾配推定手段）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention controls acceleration / deceleration means such as a throttle opening control means based on an equivalent control input equivalently generated in a sliding mode and a control input represented by a non-linear control input for constraining a system state to a switching surface. The present invention relates to a vehicle travel control device and a control method for performing vehicle travel control.
[0002]
[Prior art]
In recent years, vehicles equipped with a follow-up traveling function and a steering assist function on a highway have been commercialized, and a higher-speed and more comfortable driving support system has been proposed. One of the control technology elements at this time is a throttle control technology.
[0003]
Conventionally, linear control such as PID control has been widely used for throttle control. However, since the vehicle motion has a strong non-linearity especially immediately after starting, and a large deviation occurs from a command value, a sliding mode theory is used. It is considered to apply.
[0004]
This sliding mode theory is widely known in the field of non-linear control. Briefly, as shown in FIG. 9, a switching plane (sliding surface) in which the state of the system is represented by a switching function σ (= S (x)) Is called a sliding mode, and the sum of an equivalent control input ueq, which is equivalently generated at this time, and a non-linear control input unl for converging the state of the system to the switching plane. ueq + unl) can represent the control command value u (= ueq + unl) in the sliding mode. Here, the non-linear control input unl is determined based on a normally assumed maximum external force or the like.
[0005]
Such a sliding mode theory has also been applied to vehicle motion control in general, and application to, for example, throttle control and slip control has been conventionally proposed (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-11-159365 (pages 2-3)
[0007]
[Problems to be solved by the invention]
However, when the sliding mode theory is applied to the acceleration / speed control using the throttle, the vehicle motion responds more to the throttle opening in the lower speed range. Therefore, as described above, the nonlinear control is performed based on the assumed maximum external force and the like. If the input unl is determined, hunting may actually occur in an environment where external force is small or in a low speed range, and there is a problem that stability is lacking.
[0008]
Therefore, an object of the present invention is to provide a traveling control device and a method capable of improving stability in an environment where external force is small or in a low-speed range, and capable of coping with an environment where external force is large.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, a vehicle travel control device according to the present invention is represented by an equivalent control input that is equivalently generated in a sliding mode, and a non-linear control input that restricts a system state to a switching surface. In a vehicle travel control device that controls the acceleration / deceleration means based on a control input to control the travel of the vehicle, when the magnitude of the switching function of the sliding mode control system is equal to or less than a predetermined value, the value is set to a value smaller than the maximum value. Storing means for storing the derivation coefficient of the nonlinear control input, and selecting a value of the coefficient according to the magnitude of the switching function from the storage means to derive the non-linear control input and calculate the control input Control input calculation means; and control means for controlling the acceleration / deceleration means based on the control input calculated by the control input calculation means. It is characterized in bets (claim 1).
[0010]
According to such a configuration, when the magnitude of the switching function of the sliding mode control system is equal to or less than a predetermined value, the non-linear control input derivation coefficient set to a value smaller than the maximum value is stored in the storage unit, The control input calculation means selects a coefficient value corresponding to the magnitude of the switching function from the storage means, derives a non-linear control input, calculates the control input, and accelerates / decelerates the control input based on the calculated control input. Means are controlled.
[0011]
Therefore, it is not necessary to select the value of the derivation coefficient of the non-linear control input from the storage means according to the magnitude of the switching function, instead of the unique non-linear control input according to the assumed maximum external force as in the related art. As a result, in the traveling control of the vehicle based on the sliding mode theory, it is possible to realize stable control in an environment with a small external force such as a road surface gradient or in a low speed range, and sufficiently cope with an environment with a large external force. it can.
[0012]
In the vehicle travel control device according to the present invention, when the magnitude of the switching function is equal to or less than a predetermined value, the coefficient decreases in proportion to a decrease in the magnitude of the switching function from the maximum value. If the size of the function is equal to or less than a predetermined value smaller than the predetermined value, the function is set to a minimum value (claim 2). At this time, as set forth in claim 3, the minimum value is set to a value that does not cause hunting in a low speed range, and the maximum value is set based on an assumed maximum disturbance. desirable.
[0013]
According to such a configuration, the value of the derivation coefficient of the non-linear control input can be appropriately selected from the storage means in accordance with the magnitude of the switching function. In this case, stable control can be realized in an environment with a small external force or in a low-speed range, and it can sufficiently cope with an environment with a large external force.
[0014]
Also, in the vehicle traveling control device according to the present invention, the acceleration / deceleration means may include a following distance sensor for detecting a following distance from a preceding vehicle, and a command for deriving a command acceleration of the own vehicle from the following distance by the following distance sensor. Acceleration deriving means, estimating means for estimating a road surface gradient, and command throttle opening deriving means for deriving a command throttle opening from the command acceleration by the command acceleration deriving means and the road surface gradient by the estimating means. Throttle opening control means, wherein the control means controls the throttle opening based on the command throttle opening derived by the command throttle opening deriving means (claim 4).
[0015]
According to such a configuration, in the throttle control based on the sliding mode theory, a stable throttle control can be realized in an environment with a small external force such as a road surface gradient or in a low speed range, and it can sufficiently cope with an environment with a large external force. Thus, stable throttle control can be realized.
[0016]
Further, in the traveling control device for a vehicle according to the present invention, the estimating means may calculate the road surface gradient from the vehicle speed estimation value and the speed by the vehicle speed estimation value deriving means for deriving the vehicle speed estimation value. And a gradient estimating means for estimating.
[0017]
According to such a configuration, since the road surface gradient can be estimated from the state of the vehicle, it is possible to derive an optimum command throttle opening corresponding to the road surface gradient.
[0018]
Further, according to the vehicle traveling control method of the present invention, an acceleration / deceleration based on an equivalent control input generated equivalently in a sliding mode and a control input represented by a non-linear control input for constraining a system state to a switching surface is provided. In the vehicle traveling control method for controlling traveling of the vehicle by controlling the means, when the magnitude of the switching function of the sliding mode control system is equal to or smaller than a predetermined value, deriving the nonlinear control input set to a value smaller than a maximum value. The coefficient for use is stored, the value of the coefficient according to the magnitude of the switching function is selected from the storage means, the nonlinear control input is derived, the control input is calculated, and the control input is calculated based on the calculated control input. The acceleration / deceleration means is controlled (claim 6).
[0019]
According to such a configuration, when the magnitude of the switching function of the sliding mode control system is equal to or less than the predetermined value, the derivation coefficient of the nonlinear control input set to a value smaller than the maximum value is stored, and the switching function of the switching function is stored. The value of the coefficient according to the magnitude is selected, the nonlinear control input is derived, the control input is calculated, and the acceleration / deceleration means is controlled based on the calculated control input. The value of the derivation coefficient of the nonlinear control input can be appropriately selected from the storage means according to the magnitude of the switching function, not the unique nonlinear control input according to the external force. In traveling control, stable control can be realized in an environment with a small external force, such as a road surface gradient, or in a low speed range, and it can sufficiently cope with an environment with a large external force.
[0020]
Further, in the vehicle traveling control method according to the present invention, the acceleration / deceleration means detects an inter-vehicle distance to a preceding vehicle, derives a command acceleration of the own vehicle from the detected inter-vehicle distance, and derives a derived vehicle speed estimation value. A throttle opening control means for estimating a road gradient from a speed and deriving a command throttle opening from the command acceleration and the road gradient (claim 7).
[0021]
According to such a configuration, in the throttle control based on the sliding mode theory, a stable throttle control can be realized in an environment with a small external force such as a road surface gradient or in a low speed range, and also in an environment with a large external force. Stable throttle control can be realized sufficiently.
[0022]
In the vehicle traveling control method according to the present invention, when the magnitude of the switching function is equal to or less than a predetermined value, the coefficient decreases in proportion to a decrease in the magnitude of the switching function from the maximum value. When the size of the function is equal to or smaller than a predetermined value smaller than the predetermined value, the function is set to the minimum value (claim 8). At this time, as set forth in claim 9, the minimum value is set to a value that does not cause hunting in a low speed range, and the maximum value is set based on an assumed maximum disturbance. Good to be.
[0023]
According to such a configuration, the value of the coefficient for deriving the non-linear control input can be appropriately selected from the storage means in accordance with the magnitude of the switching function. Therefore, in the throttle control based on the sliding mode theory, the external force such as the road surface gradient is used. Stable throttle control can be realized in an environment with a small external force or in a low-speed range, and a stable throttle control can be realized sufficiently in an environment with a large external force.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment in which the present invention is applied to a throttle control of a vehicle will be described with reference to FIGS. 1 is an external view of an applied vehicle, FIG. 2 is a block diagram of a control system, FIG. 3 is a partial block diagram of FIG. 2, and FIG. 4 is a relationship between a magnitude | σ | of a switching function σ and a coefficient k. FIG. 5 to FIG. 8 are explanatory diagrams of the operation.
[0025]
As shown in FIG. 1, a laser radar 3 as an inter-vehicle distance sensor for detecting an inter-vehicle distance to a preceding vehicle is mounted on a front portion of the vehicle body 1, and a brake actuator 5 and a throttle actuator 7 are mounted. The engine is a naturally aspirated engine, and the transmission is a belt-type continuously variable transmission (CVT).
[0026]
As shown in FIG. 2, the control system includes an inter-vehicle distance controller 9 and a throttle controller 11 as command acceleration deriving means. The inter-vehicle distance controller 9 detects the inter-vehicle distance to the preceding vehicle detected by the laser radar 3, Further, based on a vehicle speed v detected by a vehicle speed sensor (not shown), a command acceleration A * is derived and output.
[0027]
The throttle controller 11 derives and outputs a commanded throttle opening degree θ * for a vehicle motion system 13 such as a throttle and an engine. The sliding controller 15 controls the sliding control, and an estimating means for estimating a road surface gradient which is a disturbance factor. And a disturbance observer 17.
[0028]
Here, the sliding controller 15 has a built-in memory (not shown) such as a ROM as storage means for storing a coefficient k for deriving the non-linear control input unl, and the coefficient k is, as shown in FIG. Is set to the maximum value k1 when the magnitude | σ | of the switching function σ is larger than the predetermined value σ1, and the magnitude | σ | of the switching function σ when the magnitude | σ | Decreases in proportion to the decrease of the switching function σ, and when the magnitude | σ | of the switching function σ is equal to or smaller than a predetermined value σ0 (<σ1) smaller than the predetermined value σ1, the minimum value k0 is set. A coefficient k that changes according to σ | is stored in a memory in advance in a table format. Note that the minimum value k0 is set to a value that does not cause hunting in a low-speed range, and the maximum value k1 is set based on the assumed maximum disturbance (here, the assumed maximum road surface gradient). .
[0029]
Then, the sliding controller 15 selects the value of the coefficient k according to the magnitude | σ | of the switching function σ from the memory, derives the non-linear control input unl, calculates the control input u, and gives the calculated control input u Based on this, the command throttle opening θ * is derived and output to the vehicle motion system 13 as acceleration / deceleration means, and the throttle actuator 7 is driven to control the throttle opening of the electronically controlled throttle.
[0030]
The processing of calculating the control input u by the sliding controller 15 corresponds to control input calculating means in the present invention, and the processing of deriving the command throttle opening θ * corresponds to the command throttle opening deriving means in the present invention. The degree control process corresponds to control means in the present invention.
[0031]
Further, the laser radar 3, the inter-vehicle distance controller 9, the disturbance observer 17, and the sliding controller 15 as command throttle opening deriving means constitute throttle opening control means as acceleration / deceleration means.
[0032]
As shown in FIG. 3, the disturbance observer 17 includes a command throttle opening input / vehicle speed output model (Gcm) 171, an inverse model (1 / Gdm) 173 of the external force input / vehicle speed output model (Gdm), and a primary And a low-pass filter (Gf) 175 composed of a delay filter.
[0033]
The command throttle opening input / vehicle speed output model (Gcm) 171 corresponds to the vehicle speed estimation value deriving means in the present invention. The command throttle opening input / vehicle speed output model (Gcm) 171 converts the command throttle opening θ * into the command throttle opening θ *. The vehicle speed estimation value Ev is derived based on the vehicle speed. The inverse model (1 / Gdm) 173 of the external force input / vehicle speed output model corresponds to the gradient estimating means in the present invention, and the estimated vehicle speed Ev and the vehicle speed are calculated by the inverse model (1 / Gdm) 173 of the external force input / vehicle output model. The road surface gradient is estimated based on v, a noise component is removed by a low-pass filter (Gf) 175, and the road surface gradient estimated value Ed is output to the sliding controller 15.
[0034]
The derivation of the road surface gradient estimated value Ed is derived by the operation of Expression 1. In Equation 1, s is the Laplace operator, Tcm and Kcm are the time constant and gain of the command throttle opening input / vehicle speed output model (Gcm) 171, and Tdm and Kdm are the external force input / vehicle speed output model (Gdm), respectively. The constant, gain, and Tf are time constants of the low-pass filter (Gf) 175, and these Tcm, Kcm, Tdm, Kdm, and Tf are preferably adjusted in an actual vehicle.
[0035]
(Equation 1)

[0036]
On the other hand, the control input u in the sliding mode is represented by the sum (u = ueq + unl) of the equivalent control input ueq and the nonlinear control input unl, as described above. Here, the linear state equation of the servo system in the present control system is as shown in Expression 2, and the switching function σ in the sliding control is expressed by:
σ = S * x (where S is a coefficient)
In the sliding mode, Equation 3 holds, so the equivalent control input ueq is expressed by Equation 4. In Equation 2, r is the commanded vehicle speed obtained by integrating the commanded acceleration A *, d is a disturbance, a, b, and f are coefficients obtained from the motion characteristics of the vehicle to be controlled, and z is the commanded vehicle speed and the actual vehicle. The integrated value of the speed deviation, v is the actual vehicle speed of the own vehicle detected by the vehicle speed sensor, and x represents a vector composed of z and v.
[0037]
(Equation 2)

[0038]
[Equation 3]

[0039]
(Equation 4)

[0040]
From Equation 4, the equivalent control input ueq is determined by the coefficient matrix S of the switching function σ, and the stability matrix is specified by determining the switching matrix S using the solution P of the Riccati equation represented by Equation 5. Preferably, an approach is taken.
[0041]
(Equation 5)

[0042]
Next, the non-linear control input unl is represented by Expression 6, and the derivation of the non-linear control input unl changes according to the magnitude | σ | of the switching function σ as shown in FIG. 4 as described above. The coefficient k is used to prevent hunting in a low speed range and an environment with a small road surface gradient (external force). In Expression 6, δ is a positive number and is a coefficient for preventing chattering, and k is an influence of an external force (here, a road surface gradient) for realizing the convergence of the switching function σ to 0 or a model. It is a coefficient set in consideration of the conversion error.
[0043]
(Equation 6)

[0044]
FIG. 5 shows a control result when the experimental vehicle follows the flat road. This result is obtained when the vehicle speed follows a preceding vehicle accelerated from a state of about 10 km / h. FIG. 5 shows that the commanded acceleration (A *) is either immediately after acceleration or in a steady state where the commanded acceleration is small. Also, it can be seen that overshoot and undershoot are small and that the vehicle can follow well. On the other hand, the result of the conventional PID control is shown in FIG. 6 for comparison. In this PID control, the overshoot and the undershoot are very large and stable with respect to the commanded acceleration because the nonlinearity of the vehicle cannot be coped with. It turns out that it lacks sex.
[0045]
Subsequently, the control results on the uphill road and the downhill road are shown in FIGS. 7 and 8, respectively. These results are obtained when the vehicle follows the preceding vehicle accelerated from the almost stopped state on the approximately 7% gradient road. From FIGS. 7 and 8, it can be seen from FIGS. It can be seen that the chute was small and it was able to follow well. In particular, on an uphill road, the control gain is set to be high according to the road surface gradient type (uphill gradient) based on the road surface gradient estimated value Ed from the disturbance observer 17, and the state of the system moves away from the switching plane. It is inferred that such a result was caused by the increase in the non-linear control input unl. The flutter of the actual acceleration immediately after the start of the control in FIG. 8 is caused by the movement of the vehicle accompanying the release of the brake.
[0046]
Thus, when the magnitude | σ | of the switching function σ of the sliding mode control system is larger than the predetermined value σ1, the maximum value k1 is obtained, and when the magnitude | σ | of the switching function σ is smaller than the predetermined value σ0 smaller than the predetermined value σ1, A coefficient k set to the minimum value k0 and set so that the magnitude | σ | of the switching function σ decreases between σ1 and σ0 in proportion to the decrease of the magnitude | σ | 15, the value of the coefficient k according to the magnitude | σ | of the switching function σ based on the road surface gradient estimated value Ed is selected from the memory, the nonlinear control input unl is derived, and the control input u is obtained. Based on the calculated control input u, the optimum command throttle opening θ * corresponding to the road surface gradient is derived, and the throttle opening control means is controlled.
[0047]
Therefore, according to the above-described embodiment, the non-linear control input unl according to the magnitude | σ | of the switching function σ is not a unique nonlinear control input unl according to the assumed maximum external force as in the related art. The value of the derivation coefficient k can be appropriately selected from the memory of the sliding controller 15, and as a result, in throttle control based on the sliding mode theory, stable control can be realized in an environment with a small road gradient or in a low speed range. At the same time, it can sufficiently cope with an environment having a large road gradient.
[0048]
The coefficient k is a maximum value k1 when the magnitude | σ | of the switching function σ is larger than the predetermined value σ1, and a minimum value k0 when the magnitude | σ | of the switching function σ is smaller than the predetermined value σ1. And the magnitude | σ | of the switching function σ is set so as to decrease in proportion to the decrease of the magnitude | σ | of the switching function σ between σ1 and σ0, and the minimum value k0 of the coefficient k is Is set to a value that does not cause hunting in a low speed range, and the maximum value k1 is set based on the assumed maximum road surface gradient, so that the coefficient k corresponding to the magnitude | σ | The value can be selected appropriately.
[0049]
Further, since the road surface gradient can be estimated from the condition of the vehicle, an optimum command throttle opening θ * corresponding to the road surface gradient can be derived, and stable throttle control can be realized.
[0050]
The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.
[0051]
For example, in the above-described embodiment, the memory as the storage unit is described as a ROM or the like built in the sliding controller 15, but it is needless to say that an external memory may be used as the storage unit.
[0052]
Further, in the above-described embodiment, an example in which the present invention is applied to the throttle control has been described. However, it is needless to say that the present invention can be similarly applied to traveling control of other vehicles. The effect can be obtained.
[0053]
【The invention's effect】
As described above, according to the first and sixth aspects of the present invention, the value of the coefficient corresponding to the magnitude of the switching function is selected, the nonlinear control input is derived, the control input is calculated, and the calculated control is performed. Since the acceleration / deceleration means is controlled based on the input, it is not a unique non-linear control input according to the assumed maximum external force as in the related art, but a coefficient for deriving the non-linear control input according to the magnitude of the switching function. The value can be appropriately selected from the storage means. As a result, in the traveling control of the vehicle based on the sliding mode theory, stable control can be realized in an environment with a small external force such as a road surface gradient or in a low speed range, and It is possible to sufficiently cope with an environment with a large size.
[0054]
According to the second and third aspects of the present invention, the value of the coefficient for deriving the nonlinear control input can be appropriately selected from the storage means in accordance with the magnitude of the switching function. In running control, stable control can be realized in an environment with a small external force such as a road surface gradient or in a low speed range, and it is possible to sufficiently cope with an environment with a large external force.
[0055]
According to the fourth aspect of the invention, in the throttle control based on the sliding mode theory, a stable throttle control can be realized in an environment where the external force such as a road surface gradient is small or in a low speed range, and the external force is large. It is possible to realize stable throttle control that sufficiently responds to the environment.
[0056]
According to the fifth aspect of the present invention, since the road surface gradient can be estimated from the condition of the vehicle, it is possible to derive an optimal command throttle opening corresponding to the road surface gradient and realize stable throttle control. become.
[0057]
According to the seventh aspect of the invention, in the throttle control based on the sliding mode theory, a stable throttle control can be realized in an environment where the external force is small such as a road surface gradient or in a low speed range, and the external force is large. It is possible to realize stable throttle control that sufficiently responds to the environment.
[0058]
According to the eighth and ninth aspects of the invention, the value of the coefficient for deriving the non-linear control input can be appropriately selected from the storage means in accordance with the magnitude of the switching function. In this case, stable throttle control can be realized in an environment with a small external force such as a road surface gradient or in a low speed range, and stable throttle control can be realized sufficiently in an environment with a large external force.
[Brief description of the drawings]
FIG. 1 is an external perspective view of an applied vehicle according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control system according to an embodiment of the present invention.
FIG. 3 is a partial block diagram of FIG. 2;
FIG. 4 is an operation explanatory diagram according to the embodiment of the present invention.
FIG. 5 is an operation explanatory diagram in one embodiment of the present invention.
FIG. 6 is an operation explanatory diagram according to the embodiment of the present invention.
FIG. 7 is an operation explanatory diagram according to the embodiment of the present invention.
FIG. 8 is an operation explanatory diagram in one embodiment of the present invention.
FIG. 9 is an explanatory diagram of sliding control as a background of the present invention.
[Explanation of symbols]
3 Laser radar (inter-vehicle distance sensor, throttle opening control means)
9 Inter-vehicle distance controller (command acceleration derivation means, throttle opening degree control means)
15. Sliding controller (control input calculation means, command throttle opening derivation means, control means, throttle opening control means)
17 disturbance observer (estimation means, throttle opening control means)
171 Command throttle opening input / vehicle speed output model (vehicle speed estimated value deriving means)
173 Inverse model of external force input / vehicle speed output model (gradient estimation means)

Claims (9)

An equivalent control input that is equivalently generated in the sliding mode, and a control input that is controlled by a non-linear control input for constraining the system state to the switching surface. In the travel control device,
When the magnitude of the switching function of the sliding mode control system is equal to or smaller than a predetermined value, storage means for storing a derivation coefficient of the nonlinear control input set to a value smaller than a maximum value,
Control input calculation means for selecting the value of the coefficient according to the magnitude of the switching function from the storage means, deriving the non-linear control input, and calculating the control input;
Control means for controlling the acceleration / deceleration means based on the control input calculated by the control input calculation means. When the magnitude of the switching function is equal to or less than a predetermined value, the coefficient decreases from the maximum value in proportion to a decrease in the magnitude of the switching function, and the magnitude of the switching function is equal to or less than a predetermined value that is smaller than the predetermined value. 2. The vehicle travel control device according to claim 1, wherein a minimum value is set. The method according to claim 2, wherein the minimum value is set to a value that does not cause hunting in a low speed range, and the maximum value is set based on an assumed maximum disturbance. Vehicle travel control device. The acceleration / deceleration means,
An inter-vehicle distance sensor that detects an inter-vehicle distance from a preceding vehicle; command acceleration deriving means for deriving a command acceleration of the own vehicle from the inter-vehicle distance by the inter-vehicle distance sensor; estimating means for estimating a road surface gradient; and the command acceleration deriving means Command throttle opening deriving means for deriving a command throttle opening from the road acceleration obtained by the command acceleration and the road surface gradient by the estimating means.
The travel control device for a vehicle according to any one of claims 1 to 3, wherein the control means controls the throttle opening based on the command throttle opening derived by the command throttle opening deriving means. . The estimating means includes:
Vehicle speed estimated value deriving means for deriving a vehicle speed estimated value;
The vehicle travel control device according to claim 4, further comprising a gradient estimating unit that estimates the road surface gradient from the vehicle speed estimated value and the speed by the vehicle speed estimated value deriving unit. An equivalent control input that is equivalently generated in the sliding mode, and a control input that is controlled by a non-linear control input for constraining the system state to the switching surface. In the traveling control method,
When the magnitude of the switching function of the sliding mode control system is equal to or less than a predetermined value, a derivation coefficient of the nonlinear control input set to a value smaller than a maximum value is stored,
Calculating the control input by selecting the value of the coefficient according to the magnitude of the switching function from the storage means, deriving the non-linear control input,
A vehicle traveling control method, wherein the acceleration / deceleration means is controlled based on the calculated control input. The acceleration / deceleration means,
Detecting the inter-vehicle distance to the preceding vehicle, deriving the commanded acceleration of the own vehicle from the detected inter-vehicle distance, estimating a road surface gradient from the derived vehicle speed estimation value and speed, and instructing a command throttle from the commanded acceleration and the road surface gradient. 7. The vehicle running control method according to claim 6, wherein the throttle opening control means derives an opening. When the magnitude of the switching function is equal to or less than a predetermined value, the coefficient decreases from the maximum value in proportion to a decrease in the magnitude of the switching function, and the magnitude of the switching function is equal to or less than a predetermined value that is smaller than the predetermined value. The vehicle travel control method according to claim 6 or 7, wherein the vehicle is set to a minimum value. 9. The method according to claim 8, wherein the minimum value is set to a value that does not cause hunting in a low speed range, and the maximum value is set based on an assumed maximum disturbance. Vehicle running control method.

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