JP4041911B2 - Steering control method for four-wheel independent steering vehicle - Google Patents

Description

The present invention relates to a steering control method for a vehicle (especially an electric mobile vehicle) that travels by four-wheel independent steering, and the vehicle is operated in a steering mode that adapts to the path configuration of a facility where the vehicle is traveling and the arrangement of objects around the path. The present invention relates to a vehicle steering control method for smoothly and safely traveling a vehicle. In the present invention, the “steering mode” means a trace pattern drawn by each wheel of the vehicle by steering.

Multiple steering modes for four-wheel independent steering vehicles running in various indoor and outdoor facilities such as medical institutions, welfare facilities, factories, distribution bases, computer storage buildings, large commercial facilities, libraries, sports / entertainment facilities, amusement parks, etc. In the starting and running process of the vehicle, an appropriate steering mode is selected from among the plurality of types of steering modes according to the path configuration of the indoor / outdoor facilities and the arrangement situation of objects around the path. A method for traveling control of an electric vehicle with wheel independent steering has already been proposed in Japanese Patent Laid-Open No. 2003-146234 (Patent Document 1). Further, in the process of changing the steering angles α ₁ , α ₂ , α ₃ , α _{4 of the} four independently steered wheels in the selected one steering mode, the so-called “open / close leg phenomenon” relating to the left and right wheels is prevented. Thus, a means for safe driving was presented in Japanese Patent Application No. 2003-136158 (Patent Document 2). The "open / close leg phenomenon" refers to an open leg phenomenon in which the mutual orientation of the left and right wheels is expanded with respect to the traveling direction of the vehicle, and the mutual orientation of the left and right wheels precedes the traveling direction of the vehicle. It is a collective term for both the closed-leg phenomenon that causes a sag.

That is, Japanese Patent Laid-Open No. 2003-146234 (Patent Document 1) discloses several types of electric mobile vehicles in which left and right front wheels and left and right rear wheels are respectively steering-controlled by individual steering motors. Steering mode is shown. As an example of the steering mode, a steering mode M ₁ (where the traveling locus of the right rear wheel and the traveling locus of the left rear wheel follow the traveling locus of the right front wheel and the traveling locus of the left front wheel, respectively. FIG. 3 of Patent Document 1), steering mode M _{3 in which} the turning trajectory of the rear wheel becomes a so-called inner wheel difference trajectory with respect to the trajectory of the front wheel (see FIG. 5 of Patent Document 1), and the vehicle centering on the right rear wheel. steering mode M ₄ the vehicle is steered counterclockwise around the or left rear wheel to pivot clockwise _(see FIG. 6 of Patent Document 1), or to turn the vehicle to the right direction around the front right wheel Are shown steering mode M ₅ turn the vehicle around the front wheel counterclockwise _(see FIG. 7 of Patent Document 1), the steering mode M _1, M 3, _{M 4,} passages in the form from the M ₅ And a steering mode suitable for the situation around the passage and the steering angle α ₁ , α ₂ , α ₃ , α ₄ of each wheel necessary for the formation of the selected steering mode is determined as a steering constraint condition equation (abbreviated as “condition”). A method is shown in which the vehicle is steered by controlling the rotation of the steering motor of each wheel based on the steering angles α ₁ , α ₂ , α ₃ , α ₄ .

・・・・・式（Ｅ１１）

・・・・・式（Ｅ１２）

操舵モードＭ３に対して（特許文献１の図１、図５参照）：

・・・・・式（Ｅ３１）

・・・・・式（Ｅ３２）

・・・・・式（Ｅ３３）

操舵モードＭ４に対して（特許文献１の図１、図６参照）：
右旋回時において、

・・・・・式（Ｅ４１）

・・・・・式（Ｅ４２）

・・・・・式（Ｅ４３）

左旋回時において、

・・・・・式（Ｅ４５）

・・・・・式（Ｅ４６）

・・・・・式（Ｅ４７）

操舵モードＭ５に対して（特許文献１の図１、図７参照）：
右旋回時において、

・・・・・式（Ｅ５１）

・・・・・式（Ｅ５２）

・・・・・式（Ｅ５３）

左旋回時において、

・・・・・式（Ｅ５５）

・・・・・式（Ｅ５６）

・・・・・式（Ｅ５７）

なお上記条件式において、
α_１：右前車輪に対する操舵角度．
α_２：左前車輪に対する操舵角度．
α_３：右後車輪に対する操舵角度．
α_４：左後車輪に対する操舵角度．
Ｌ ：前車輪と後車輪の間の中心線Ｘと各車輪の間の距離．
Ｗ ：車輪と左車輪の間の中心線Ｙと各車輪の間の距離．
Ｒ ：各車輪の旋回軌跡が同心円弧となる場合の、同心円弧の中心と、各車輪の位置に対する中心点の間の距離．（車両の中心から車両の旋回中心までの距離）(すなわち車両の旋回半径） Then, the steering angles α ₁ , α ₂ , α _{3 of the} respective wheels (right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ ) necessary for forming each steering mode described above. , as the steering constraint condition equations for alpha _4, are shown the following Shoshiki.

For the steering mode M1 (see FIGS. 1 and 3 of Patent Document 1):

... Formula (E11)

... Formula (E12)

For the steering mode M3 (see FIGS. 1 and 5 of Patent Document 1):

... Formula (E31)

... Formula (E32)

... Formula (E33)

For the steering mode M4 (see FIGS. 1 and 6 of Patent Document 1):
When turning right,

... Formula (E41)

... Formula (E42)

... Formula (E43)

When turning left,

... Formula (E45)

... Formula (E46)

... Formula (E47)

For the steering mode M5 (see FIGS. 1 and 7 of Patent Document 1):
When turning right,

... Formula (E51)

... Formula (E52)

... Formula (E53)

When turning left,

... Formula (E55)

... Formula (E56)

... Formula (E57)

In the above conditional expression,
α ₁ : Steering angle with respect to the right front wheel.
α ₂ : Steering angle with respect to the left front wheel.
α ₃ : Steering angle with respect to the right rear wheel.
α ₄ : Steering angle with respect to the left rear wheel.
L: Distance between the center line X between the front wheel and the rear wheel and each wheel.
W: Distance between the center line Y between the wheel and the left wheel and each wheel.
R: Distance between the center of the concentric arc and the center point with respect to the position of each wheel when the turning trajectory of each wheel is a concentric arc. (Distance from vehicle center to vehicle turning center) (ie vehicle turning radius)

On the other hand, in order to change the traveling direction of the vehicle, by using the distance (turning radius of the vehicle) R as the steering command value and increasing or decreasing the steering command value R, the steering angle α of each wheel according to the steering constraint condition formula described above. _When changing the traveling direction of the vehicle by decreasing or increasing ₁ , ₁ , ₂ , ₃ , ₄ , the setting of the steering command value R is changed from the current steering command value R ₁ to the desired steering command value R ₂ . Since there is a slight time difference (steering command following time) until the steering angle α ₁ , α ₂ , α ₃ , α _{4 of} each wheel reaches a new steering angle defined by the steering constraint conditional expression, In the steering process during the steering command follow time, the left and right wheels are in a state where the mutual orientation of the left and right wheels spreads out with respect to the traveling direction of the vehicle, and the mutual orientation of the left and right wheels is relative to the traveling direction of the vehicle. A closed leg phenomenon occurs that becomes a pointed state Or causing the failure opening and closing the legs phenomenon by and excessive force is applied to the steering mechanism, accompanied by fear that stability of the person or object on the vehicle may be impaired.

In order to prevent this open / close leg phenomenon, in the above-mentioned Japanese Patent Application No. 2003-136158, the steering angles α ₁ , α ₂ , α _{3 of the} respective wheels according to the steering constraint condition formula for forming the selected steering mode. , Α ₄ individually, in steering control to change the traveling direction of the vehicle, the distance R between the center point of the concentric arc when the turning trajectory of each wheel becomes a concentric arc and the center point with respect to the position of each wheel The steering command value R is changed from R ₁ to R _2, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels are changed to the steering angle values corresponding to the steering command value R ₁ [ _{α 1, α 2, α 3} , α 4] each steering angle corresponding to the steering command value _{R 2} from _{R1 [α 1, α 2,} α 3, in the process of transition to alpha _{4] R2,} the steering command value _{R 1} steering command value obtained by adding a small steering command value [Delta] R to (R 1 ₊ ΔR) previously for Small transition steering angles that satisfy the steering constraint condition expression _{[α 1, α 2, α} 3, α 4] (R1 + ΔR) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + ΔR ₎ , The steering angles α ₁ , α ₂ , α ₃ , α ₄ are changed, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ are changed to the minute transition steering angles [α ₁ , α ₂ , α _{3, α 4]} after detecting that the matched steering angle reaches the _{(R1 + ΔR),} to the steering command value _{(R 1} + ΔR) further steering command value obtained by adding a small steering command value ΔR _(R 1 + 2ΔR) On the other hand, a minute transition steering angle [α1, α2, α3, α4] _{(R1 + 2ΔR)} that satisfies the steering constraint condition is calculated, and the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR) is calculated.} each steering angle _{α 1, α 2, α 3} , by changing the alpha ₄ toward the similarly thereafter, each Steering angle alpha ₁ of the _wheel, alpha _2, alpha _3, after the alpha ₄ detects that it has matched the steering angle, the steering constraint condition to successively added steering command value small steering command value ΔR (R 1 ₊ nΔR) A small transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + nΔR) satisfying the equation} is calculated and _{directed toward} the small transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + nΔR)} . Each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed, and each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed to a minute transition steering angle [α ₁ , α ₂ , α ₃ , α _4. ] _{(R1 + nΔR)} is reached and the detection that the steering angle is matched is repeated, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels are set to the respective steering angles [α ₁ , α ₂ , α ₃ , alpha _4] each steering angle from _{(R1) [α 1, α} 2, α 3, α 4] 4 -wheel which is adapted to vary the _(R2) Steering control method of standing steering vehicle has been proposed.

However, all of those proposed in the above-mentioned Japanese Patent Application Laid-Open No. 2003-146234 and Japanese Patent Application No. 2003-136158 apply to the steering restraint condition formulas for the respective steering modes M ₁ , M ₃ , M ₄ , and M _5. (E11-12), (E31-33), (E41-43), (E45-47), (E51-53), (E55-57) can be applied to the calculation of all the selected steering modes. It is not a common conditional expression. Therefore, when a vehicle running in a certain steering mode is changed to another steering mode to continue running, the setting is changed after changing the setting to another steering constraint conditional expression having a different form after temporarily stopping the vehicle. It is necessary to restart the vehicle in another steering mode based on the calculation according to the following steering constraint conditional expression. That is, in the conventional steering control method for a four-wheel independent steering vehicle, the steering mode cannot be shifted to another steering mode without temporarily stopping the running vehicle. This was a major difficulty in putting a four-wheel independent steering vehicle into practical use, which can be smoothly and quickly steered while freely selecting various steering modes depending on the form and the arrangement of objects around the passage.

Japanese Patent Laid-Open No. 2003-146234 Japanese Patent Application No. 2003-136158

An object of the present invention is to temporarily stop a traveling four-wheel independent steering vehicle in a four-wheel independent steering vehicle that travels in an appropriate steering mode by changing the steering mode according to the form of the vehicle passage and the state of the periphery of the passage. The steering mode can be changed quickly and smoothly during the traveling process. Another object of the present invention is to prevent the opening / closing leg phenomenon of the wheels from occurring in the change process (transition process) of the steering mode.

In order to achieve the above-mentioned problems / objectives, the present invention can be achieved without temporarily stopping a four-wheel independent steering vehicle that is running in a four-wheel independent steering vehicle that selects a steering mode and travels in an appropriate steering mode. In order to make it possible to smoothly change the steering mode in the running process, the steering constraint condition formula that defines the steering angle of each wheel in each of a plurality of selectable steering modes can be applied to all the selected steering modes. A common conditional expression of the form.

に従って演算して操舵制御する。 The present invention is based on the technical idea of using the same form of steering restraint conditional expression that can be applied in common to all selectable steering modes, and is arranged at the corners of the virtual quadrangle, respectively, on the vehicle body base. The center point O for the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ that are independently steered is set as the coordinate origin, and the left and right front wheels P ₂ pass through the center point O. , P ₁ and the left and right rear wheels P ₄ , P ₃ extending in the left-right direction are defined as X coordinate axes, and the front / rear right wheels P ₁ , P ₃ and front / rear left wheels P ₂ are passed through the center point O. , a line extending in the longitudinal direction of the P ₄ and Y axes, the same respective pivot point of the left and right front wheels P ₂ required to the vehicle body based _swirling, P ₁ and left and right rear wheels P _4, P ₃ During the same common turning as the common turning center point C The X and Y coordinates of the center point C are (R, m), the distance from the X coordinate axis of each of the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ is L, and the left and right front The distance from the Y coordinate axis of each of the wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ is W, and the X and Y coordinates (R, m) of the same common turning center point C are steering commands. As the values R and m, the steering angles α ₁ , α ₂ , α ₃ and α ₄ of the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ and the left rear wheel P ₄ are expressed by the following steering constraint conditional expressions ,

According to the calculation, steering control is performed.

に従って演算すると共に、その操舵指令値ｍ又は／及びＲを変化させることにより操舵モードを変えて操舵制御を行う。 In order to achieve the above-described problems and objects, the present invention provides a steering control method for a four-wheel independently-steered vehicle in which the vehicle is driven by changing the steering mode, and is disposed at each corner of a virtual quadrangle and arranged on the vehicle body base. The center point O for the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , and left rear wheel P ₄ that are installed and independently controlled is the coordinate origin, and the left and right front wheels P pass through the center point O. ₂ , P ₁ and the left and right rear wheels P ₄ , P ₃ extending in the left-right direction are taken as X coordinate axes, and the front / rear right wheels P ₁ , P ₃ and front / rear left wheels P are passed through the center point O. ₂ , P ₄ extending in the front-rear direction is defined as the Y coordinate axis, and the respective turning center points of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ required for turning the vehicle body base are defined. The same common turning center point C, and the same common turning point The X and Y coordinates of the rotation center point C are (R, m), and the distances from the X coordinate axes of the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ are L, The distance from the Y coordinate axis of each of the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ is W, and the X and Y coordinates (R, m) of the same common turning center C Are steering command values R, m, and the steering angles α ₁ , α ₂ , α ₃ , α of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , right rear wheel P ₃ , left rear wheel P _{4 4} is the following steering constraint conditional expression:

And the steering command value m or / and R is changed to change the steering mode and perform the steering control.

に従って演算して操舵制御し、前記操舵指令値ｍ又は／及びＲを変化させることにより操舵モードを変えて操舵制御を行う。 In addition, in the steering control method for a four-wheel independent steering vehicle in which the vehicle is driven while changing the steering mode, each corner portion of the virtual quadrangular shape is used to prevent the opening / closing leg phenomenon of the wheels in the process of changing the steering mode. The center point O for the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ , which is positioned and disposed on the vehicle body base and independently controlled, is set as the coordinate origin, and the center point O is The left and right front wheels required to turn the vehicle body base with the line extending in the left-right direction of each wheel passing through as the X coordinate axis and the line extending through the center point O extending in the front-rear direction of each wheel as the Y coordinate axis The turning center points of P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ are defined as the same common turning center point C, and the X and Y coordinates of the same common turning center point C are represented by (R, m ) And left The distance from the X coordinate axis of the right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ is L, and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ , The distance of P ₃ from the Y coordinate axis is W, the X coordinate / Y coordinate (R, m) of the same common turning center point C is the steering command value R, m, and the steering command value m or / and R is The right front wheel P ₁ , the left front wheel P ₂ , the right, while changing and gradually changing the steering command value m or / and R in all time sections of the transition process of the steering command value m or / and R Each steering angle α ₁ , α ₂ , α ₃ , α ₄ of the rear wheel P ₃ and the left rear wheel P ₄ is expressed by the following steering constraint condition formula:

And the steering control is performed by changing the steering command value m or / and R to change the steering mode.

に従って演算して操舵制御すると共に、その操舵指令値ｍをｍ_１からｍ_２へ変えて、前記各車輪の操舵角度α_１，α_２，α_３，α_４を、操舵指令値ｍ_１に対応する各操舵角度［α_１，α_２，α_３，α_４］_（ｍ１） から、操舵指令値ｍ_２に対応する操舵角度［α_１，α_２，α_３，α_４］_（ｍ２） へ移行させる過程で、操舵指令値ｍ_１に微小操舵指令値Δｍを加えた操舵指令値（ｍ_１＋Δｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋Δｍ）} を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋Δｍ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、各操舵角度α_１，α_２，α_３，α_４が前記微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋Δｍ）}に到達した後、前記操舵指令値（ｍ_１＋Δｍ）に更に微小操舵指令値Δｍを加えた操舵指令値（ｍ_１＋２Δｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋２Δｍ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋２Δｍ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、以後同様に、微小操舵指令値Δｍを順次加えた操舵指令値（ｍ_１＋ｎΔｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋ｎΔｍ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（ｍ１＋ｎΔｍ）} に向けて各操舵角度α_１，α_２，α_３，α_４を変化させることを繰り返して、各車輪の操舵角度α_１，α_２，α_３，α_４をそれぞれ各操舵角度［α_１，α_２，α_３，α_４］_（ｍ１） から各操舵角度［α_１，α_２，α_３，α_４］_（ｍ２） へ変化させて操舵制御を行う。 According to the present invention, in the steering control method for a four-wheel independent steering vehicle in which the vehicle is driven by changing the steering mode, the right front wheel is disposed at the corner of the virtual quadrangle and is disposed on the vehicle body base and independently controlled by each other. The center point O for P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is the coordinate origin, and the line extending through the center point O in the left-right direction of each wheel is the X coordinate axis. A line extending through the center point O in the front-rear direction of each wheel is a Y coordinate axis, and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ required for turning the vehicle body base Each turning center point is the same common turning center point C, and the X and Y coordinates of the same common turning center point C are (R, m), and the left and right front wheels P ₂ and P ₁ and the left and right rear points the wheels _P 4, _{P 3} The distance from the axis is L, the distance from the Y coordinate axis of the left and right front wheels P _2, P ₁ and left and right rear wheels P _4, P ₃ and W, X coordinates of the same common pivot point C With the Y coordinate (R, m) as steering command values R, m, the steering angles α ₁ , α ₂ of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ , α ₃ and α ₄ are expressed by the following steering restraint conditional expression:

The steering command value m is changed from m ₁ to m _2, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels correspond to the steering command value m ₁ . The steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 )} to be shifted to the steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _(m2) corresponding to the steering command value m ₂ in the process of, the steering command value m steering command value obtained by adding a small steering command value Delta] m to ₁ (m _{1 +} Δm) small transition steering angles that satisfy the steering constraint condition expression for _{[α 1, α 2, α} 3, α _{4] (m1 + Δm)} computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (m1 + Δm) each steering angle alpha ₁ toward, alpha _2, alpha _3, changes the alpha ₄ Each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed to the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{( m1 + Delta] m)} after reaching, the steering command value (m 1 _{+ Δm)} further steering command value obtained by adding a small steering command value Δm (m 1 ₊ 2Δm) small transition steering angles that satisfy the steering constraint condition expression for [alpha ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + 2Δm)} , and each steering angle α ₁ , α ₂ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + 2Δm).} , Α ₃ , α ₄ are changed, and thereafter, similarly, a small transition steering angle [α ₁ , α that satisfies the steering constraint condition formula with respect to a steering command value (m ₁ + nΔm) obtained by sequentially adding a small steering command value Δm. ₂ , α ₃ , α ₄ ] _{(m1 + nΔm)} and calculate each steering angle α ₁ , α ₂ , α ₃ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + nΔm).} , repeatedly varying the alpha _4, the steering angle of each wheel alpha ₁ α _2, α _3, the steering angle alpha ₄ each _{[α 1, α 2, α} 3, α 4] each steering angle from _{(m1) [α 1, α} 2, α 3, α 4] to _(m2) Change the steering control.

に従って演算して操舵制御すると共に、その操舵指令値ＲをＲ_１からＲ_２へ変えて、前記各車輪の操舵角度α_１，α_２，α_３，α_４を、操舵指令値Ｒ_１に対応する各操舵角度［α_１，α_２，α_３，α_４］_（Ｒ１） から、操舵指令値Ｒ_２に対応する操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ２））} へ移行させる過程で、操舵指令値Ｒ_１に微小操舵指令値ΔＲを加えた操舵指令値（Ｒ_１＋ΔＲ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ）} を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、各操舵角度α_１，α_２，α_３，α_４が前記微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ）}に到達した後、前記操舵指令値（Ｒ_１＋ΔＲ）に更に微小操舵指令値ΔＲを加えた操舵指令値（Ｒ_１＋２ΔＲ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋２ΔＲ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋２ΔＲ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、以後同様に、微小操舵指令値ΔＲを順次加えた操舵指令値（Ｒ_１＋ｎΔＲ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ｎΔＲ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ｎΔＲ）} に向けて各操舵角度α_１，α_２，α_３，α_４を変化させることを繰り返して、各車輪の操舵角度α_１，α_２，α_３，α_４をそれぞれ各操舵角度［α_１，α_２，α_３，α_４］_（Ｒ１） から各操舵角度［α_１，α_２，α_３，α_４］_（Ｒ２） へ変化させて操舵制御を行う。 According to the present invention, in the steering control method for a four-wheel independent steering vehicle in which the vehicle is driven by changing the steering mode, the right front wheel is disposed on the corner portion of the virtual quadrangle and is disposed on the vehicle body base and independently controlled by each other. The center point O for P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is the coordinate origin, and the line extending through the center point O in the left-right direction of each wheel is the X coordinate axis. A line extending through the center point O in the front-rear direction of each wheel is a Y coordinate axis, and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ required for turning the vehicle body base Each turning center point is the same common turning center point C, and the X and Y coordinates of the same common turning center point C are (R, m), and the left and right front wheels P ₂ and P ₁ and the left and right rear points The X seat of the wheels P ₄ and P ₃ The distance from the reference axis is L, the distance from the Y coordinate axis of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ is W, and the X of the same common turning center C The steering angles α ₁ , α ₂ of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ are set with the coordinates and Y coordinates (R, m) as steering command values R, m. , Α ₃ , α ₄ can be expressed as

The steering command value R is changed from R ₁ to R _2, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels correspond to the steering command value R ₁ . From each steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _(R1) to the steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _(R2)) corresponding to the steering command value R ₂ in the course of shifting, the steering command value obtained by adding a small steering command value [Delta] R to the steering command value R ₁ (R _{1 +} ΔR) said steering small transition steering angles that satisfy the constraint condition expression [alpha ₁ relative _to, alpha _2, alpha ₃ , Α ₄ ] _{(R1 + ΔR)} and calculate each steering angle α ₁ , α ₂ , α ₃ , α ₄ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + ΔR).} Each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed to the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ]. _{(R1 + [Delta] R)} after reaching, the steering command value (R 1 ₊ ΔR) further steering command value obtained by adding a small steering command value ΔR (R 1 ₊ 2ΔR) small transition steering angles that satisfy the steering constraint condition expression for [ _{α 1, α 2, α 3} , α 4] (R1 + 2ΔR) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + 2ΔR) each steering angle alpha ₁ towards, alpha ₂ , α ₃ , α ₄ are changed, and thereafter, similarly, a small transition steering angle [α ₁ ,... Satisfying the steering constraint conditional expression with respect to a steering command value (R ₁ + nΔR) obtained by sequentially adding a small steering command value ΔR. _{α 2, α 3, α 4} ] (R1 + nΔR) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + nΔR) each steering angle alpha ₁ toward, alpha _2, alpha _3, is repeated varying the alpha _4, the steering angle alpha ₁ of the wheels , Α ₂ , α ₃ , α ₄ are changed from the respective steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _(R1) to the respective steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _(R2). The steering control is performed by changing to.

According to the above-described means according to the present invention, in the four-wheel independent steering vehicle that can be driven while changing the steering mode, the vehicle running path can be changed in the running process without temporarily stopping the running vehicle. The vehicle can be driven by changing the steering mode accurately and smoothly in response to the form of the object and the arrangement state of the objects at the periphery of the passage. Furthermore, according to the invention means as described above, in a four-wheel independent steering vehicle capable of changing the steering mode, the opening / closing leg phenomenon of the wheel in the transition process (change process) of the steering mode is prevented, and the opening / closing leg phenomenon of the wheel is prevented. It is possible to prevent the steering mechanism from being broken or damaged due to the above, and to prevent the stability of the person or the object on the running vehicle from being impaired by the opening / closing leg phenomenon, thereby safely transferring the person or the object.

に従って演算して操舵制御すると共に、その操舵指令値ｍをｍ_１からｍ_２へ変え、その操舵指令値ＲをＲ_１からＲ_２へ変えて、各車輪の操舵角度α_１，α_２，α_３，α_４を、操舵指令値Ｒ_１，ｍ_１に対応する各操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１），（ｍ１）} から、操舵指令値Ｒ_２，ｍ_２に対応する操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ２），（ｍ２）} へ遷移させる過程で、操舵指令値Ｒ_１，ｍ_１に微小操舵指令値ΔＲ，Δｍを加えた操舵指令値（Ｒ_１＋ΔＲ），（ｍ_１＋Δｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ），（ｍ１＋Δｍ）} を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ），（ｍ１＋Δｍ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、各操舵角度α_１，α_２，α_３，α_４が前記微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ΔＲ），（ｍ１＋Δｍ）}に到達した後、前記操舵指令値（Ｒ_１＋ΔＲ），（ｍ_１＋Δｍ）に更に微小操舵指令値ΔＲ，Δｍを加えた操舵指令値（Ｒ_１＋２ΔＲ），（ｍ_１＋２Δｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋２ΔＲ），（ｍ１＋２Δｍ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋２ΔＲ），（ｍ１＋２Δｍ）}に向けて各操舵角度α_１，α_２，α_３，α_４を変化させ、以後同様に、微小操舵指令値ΔＲ，Δｍを順次加えた操舵指令値（Ｒ_１＋ｎΔＲ），（ｍ_１＋ｎΔｍ）に対して前記操舵拘束条件式を満たす微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ｎΔＲ），（ｍ１＋ｎΔｍ）}を演算し、その微小移行操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１＋ｎΔＲ），（ｍ１＋ｎΔｍ）} に向けて各操舵角度α_１，α_２，α_３，α_４を変化させることを繰り返して、各車輪の操舵角度α_１，α_２，α_３，α_４をそれぞれ各操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ１），（ｍ１）} から各操舵角度［α_１，α_２，α_３，α_４］_{（Ｒ２），（ｍ２）} へ変化させる４輪独立操舵車両の操舵制御方法である。 In the steering control method for a four-wheel independent steering vehicle in which the vehicle travels while changing the steering mode, the best embodiment of the present invention is located on the corners of the virtual quadrangle and is disposed on the vehicle body base and independently controlled. A center point O with respect to the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , and left rear wheel P ₄ is a coordinate origin, and a line extending in the left-right direction of each wheel through the center point O is defined as X The left and right front wheels P ₂ and P ₁ and the left and right rear wheels P required for turning the vehicle body base are defined as coordinate axes, and a line extending in the front-rear direction of each wheel through the center point O is defined as a Y coordinate axis. ₄ , P ₃ as the same turning center point (same common turning center point) C common to those wheels, and the X and Y coordinates of the same common turning center point C are (R M) and the left The distance from the X coordinate axis of the right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ and P ₃ is L, and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P ₄ , The distance from the Y coordinate axis of P ₃ is W, the X coordinate / Y coordinate (R, m) of the same common turning center C is the steering command value R, m, and the right front wheel P ₁ , left front wheel P ₂ , the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the right rear wheel P ₃ and the left rear wheel P ₄ are expressed by the following steering constraint condition formulas:

The steering command value m is changed from m ₁ to m ₂ , the steering command value R is changed from R ₁ to R _2, and the steering angles α ₁ , α ₂ , α of the respective wheels are calculated. _3, alpha _4, and the steering angle corresponding to the steering command value _{R 1, m 1 [α 1} , α 2, α 3, α 4] (R1), from _(m1), steering command value _R 2, _{m 2} In the process of transitioning to the steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2) corresponding} to, the small steering command values ΔR, Δm were added to the steering command values R ₁ , m ₁ A small transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + ΔR), (m1 + Δm)} that satisfies the steering constraint conditional expression is calculated with respect to the steering command values (R ₁ + ΔR), (m ₁ + Δm). and, the small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + ΔR), each toward the _{(m1 + Δm)} Rudder angle _{α 1, α 2, α 3} , by changing the alpha _4, each steering angle _{α 1, α 2, α 3} , α 4 are the small transition steering angles _{[α 1, α 2, α} 3, α 4] After reaching _{(R1 + ΔR), (m1 + Δm)} , steering command values (R ₁ + 2ΔR), (m) obtained by adding minute steering command values ΔR, Δm to the steering command values (R ₁ + ΔR), (m ₁ + Δm). ₁ + 2Δm) is calculated with respect to the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR), (m1 + 2Δm)} that satisfies the steering constraint condition formula, and the minute transition steering angle [α ₁ , [alpha] ₂ , [alpha] ₃ , [alpha] ₄ ] _{(R1 + 2 [Delta} ] _{R), (m1 + 2 [Delta} ] _{m), the} steering angles [alpha] ₁ , [alpha] ₂ , [alpha] ₃ , [alpha] ₄ are changed. In addition steering command value _(R 1 + _nΔR), contracture the steering relative to _(m 1 + _nΔm) Small transition steering angles that satisfy the condition _{[α 1, α 2, α} 3, α 4] (R1 + nΔR), (m1 + nΔm) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] _{(R1 + nΔR), (m1} + nΔm) each steering angle alpha ₁ toward, α _2, α _3, repeatedly varying the alpha _4, the steering angle alpha ₁ of the _{wheels, α 2, α 3, α} 4 , respectively Each steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1), (m1) is changed} to each steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2)} . This is a steering control method for a four-wheel independent steering vehicle.

The present invention will be described below with reference to FIG. 1 showing an embodiment thereof. FIG. 1 is an explanatory reference diagram of a steering control method for a four-wheel independent steering vehicle according to the present invention. In FIG. 1, 1 is a vehicle body base of a four-wheel independent steering vehicle, and the vehicle body base 1 means a structure on which a right front wheel P ₁ , a left front wheel P ₂ , a right rear wheel P ₃ , and a left rear wheel P ₄ are mounted. . 1a is the front right wheel P _1, the front left wheel P _2, the rear right wheel P _3, a virtual square that assumes for explaining the position of the left rear wheel P _4, the front right wheel P ₁ is independently steering control, The left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ are disposed and mounted on the vehicle body base 1 in a state of being positioned at the corners of the virtual quadrangle 1a. The center point O for the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is the coordinate origin, and the line extending through the center point O in the horizontal direction of each wheel is the X coordinate axis. The center of rotation of each wheel P ₁ , P ₂ , P ₃ , P ₄ required for turning the vehicle body base 1 (vehicle) is defined by using a line extending through the center point O in the front-rear direction of each wheel as the Y coordinate axis. The point is defined as the same turning center point (same common turning center point) C common to the wheels P ₁ , P ₂ , P ₃ , P ₄ , and the X and Y coordinates of the same common turning center point C are ( R, m), L is the distance from the X coordinate axis of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ , and the left / right front wheels P ₂ , P ₁ and the left / right rear The distance from the Y coordinate axis of the wheels P ₄ and P ₃ is W, and the X seat of the same common turning center point C Steering control is performed by changing the steering mode by changing the steering command value R, m, that is, the position (coordinate) of the same common center point C, with the mark / Y coordinate (R, m) as the steering command value R, m. To do. A ₁ , A ₂ , A ₃ , and A ₄ indicate the directions (the directions of the wheels) that the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ are steered. It is shown.

・・・・・ 式（１）

・・・・・ 式（２）

・・・・・ 式（３）

・・・・・ 式（４）
What is important in the present invention is that the steering of the right front wheel P ₁ , the left front wheel P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ required for steering the vehicle body base 1 (vehicle) in several steering modes. The following formulas (1 to 4) are used as steering constraint conditional expressions for defining the angles α ₁ , α ₂ , α ₃ , and α ₄ , and the steering constraint conditional expressions (1 to 4) are selectable. This is a common formula for a plurality of steering modes.

Equation (1)

Equation (2)

Equation (3)

Equation (4)

The vehicle has an arithmetic program (not shown) for calculating the steering angles α ₁ , α ₂ , α ₃ , α ₄ according to the above formulas (1), (2), (3), and (4), and the calculation is performed. A steering motor (not shown) for steering each wheel based on the steering angles α ₁ , α ₂ , α ₃ , α ₄ is provided, and the steering command values (positions of the same common center point C) R, m are changed. As a result, the steering angles α ₁ , α ₂ , α ₃ , α _{4 of the} wheels calculated based on the steering constraint conditional expressions (1 to 4) change, and the vehicle can be steered in different steering modes. it can. Incidentally, the above-described steering the constraint condition expression (1) (2) (3) (4) the previous Patent Document 1 indicated steering constraint condition expression in the steering mode M ₁ (E11,12), the steering mode _{M 3} steering constraint condition expression (E31,32,33), steering constraint condition expression of steering mode _{M 4} (E41,42,43,45,46,47), steering constraint condition expression of steering mode _{M 5} (51,52,53 comparing the 55, 56, 57), the steering constraint condition expression according to the present invention (1) (2) (3) (4) steering constraint condition expression in the steering mode M ₁ if the steering command value m = 0 in corresponds to (E11,12), m = the case of -L corresponds to the steering constraint condition expression in the steering mode _{M 3} (E31,32,33), steering command value m = -L, steering command value R = W corresponding to steering constraint condition expression in the steering mode _{M 4} (E41,42,43,45,46,47) in the case of Tokaru that corresponds to a steering command value m = L, the steering constraint condition expression in the steering mode _{M 5} when the steering command value R = W (E51,52,53,55,56,57). Therefore, by applying the steering constraint conditional expressions (1 to 4) according to the present invention and changing the steering command values m and R, the steering modes M ₁ , M ₃ , M ₄ , M _5, etc. are different. Steering control of a four-wheel independent steering vehicle can be performed in the steering mode. Since the steering constraint conditional expressions (1 to 4) according to the present invention are conditional expressions of the same form that are common to different steering modes, the steering command is temporarily stopped without stopping the traveling while the vehicle is traveling. By changing the values m and R, the steering mode is changed quickly and smoothly, and the vehicle is driven by changing the steering mode accurately and smoothly in response to the form of the vehicle traveling path and the arrangement of objects at the periphery of the path. be able to.

In the above embodiment, when the steering mode is changed by changing the steering command values m and R, for example, the steering command value m is changed from m ₁ to m ₂ and the steering command value R is changed from R ₁ to R ₂ . When changing the steering wheel, the opening / closing leg phenomenon of the wheel is prevented from occurring in the steering mode transition process, so that stable, quick and smooth steering mode transition is executed. That is, when the steering command value m is changed from m ₁ to m ₂ and the steering command value R is changed from R ₁ to R ₂ to change the steering mode, the steering angles α ₁ , α ₂ , α ₃ , α _{4 of the} wheels are changed. From the steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1), (m1)} corresponding to the steering command values R ₁ , m ₁ , the steering corresponding to the steering command values R ₂ , m _2. In the process of transitioning to the angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2)} , a steering command value obtained by adding the small steering command values ΔR, Δm to the steering command values R ₁ , m ₁ ( A small transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + ΔR), (m1 + Δm)} that satisfies the steering constraint condition formula is calculated with respect to R ₁ + ΔR), (m ₁ + Δm), and the minute migration steering angle _{[α 1, α 2, α} 3, α 4] (R1 + ΔR), (m1 + Δm) each steering angle towards the alpha ₁ α _2, α _3, by changing the alpha _4, each steering angle _{α 1, α 2, α 3} , α 4 are the small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + ΔR), ( after reaching _{m1 + Δm),} the steering command value _{(R 1 + ΔR), (} m 1 + more small steering command value to Delta] m) [Delta] R, the steering command value plus Δm _(R 1 + 2ΔR), with respect to _(m 1 + _2Δm) Then, a small transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR), (m1 + 2Δm)} that satisfies the steering constraint conditional expression is calculated, and the small transition steering angle [α ₁ , α ₂ , α ₃ is calculated. , Α ₄ ] _{(R1 + 2ΔR), (m1 + 2Δm)} , the steering angles α ₁ , α ₂ , α ₃ , α ₄ are changed, and thereafter, similarly, the steering command value obtained by sequentially adding the minute steering command values ΔR, Δm. _(R 1 + nΔR), Mitsuru said steering constraint condition expression for _(m 1 + _nΔm) Be small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + nΔR), (m1 + nΔm) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + nΔR) _{, (M1 + nΔm)} , each steering angle α ₁ , α ₂ , α ₃ , α ₄ is repeatedly changed to change the steering angle α ₁ , α ₂ , α ₃ , α ₄ of each wheel to each steering angle. [Α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1), (m1) is changed} to each steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2)} A stable and smooth steering control of a four-wheel independent steering vehicle is achieved.

In order to improve and maintain the medical and welfare environment accompanying the aging of society, to improve and maintain the culture, education, sports and entertainment environment that contributes to improving the quality of daily life, and to further improve the business in the industry. Because of the need for rationalization and expansion, people and goods can be used indoors and outdoors in various facilities such as medical / welfare facilities, factories, logistics bases, computer-related facilities, large commercial facilities, libraries, sports facilities, amusement parks, and entertainment facilities. The demand for vehicles that can be safely transported on board is expected to increase further, and as a vehicle that meets these applications, the degree of freedom of the steering trajectory of the vehicle is high, and there is little impact or shaking during steering and traveling, What can be safely controlled by steering is considered to be particularly required. Under such circumstances, as is apparent from the above embodiment, the present invention is a four-wheel vehicle that can be driven in an appropriate steering mode by changing the steering mode in accordance with the form and peripheral state of the vehicle passage. This relates to an independently-steered vehicle, and the four-wheels that are running as a steering restraint conditional expression of the same form that can apply the steering angle of each wheel to form a plurality of selectable steering modes to all the steering modes. The steering mode can be changed quickly and smoothly in the course of traveling without stopping the independent steering vehicle, and the steering command value is gradually changed in all time sections in the change process (transition process) of the steering mode. The steering angle of each wheel is controlled according to the steering restraint condition formula to prevent the opening and closing leg phenomenon of the wheel during the transition process of the steering mode, and the impact and shaking in the steering / running vehicle are prevented. It is obtained by the Guyo. Therefore, according to the steering control method for a four-wheel independent steering vehicle according to the present invention, the degree of freedom of the steering traveling locus of the vehicle is high, and there is little impact and shaking during steering / traveling, and steering control can be performed quickly, smoothly, and safely. As a vehicle, it is highly likely to be useful for various industries that support the social and living environments that will be required in the future.

FIG. 3 is a reference diagram for explaining a steering control method for a four-wheel independent steering vehicle according to the present invention.

Explanation of symbols

1: Vehicle body base 1a: Virtual quadrangle A ₁ : Travel direction of right front wheel A ₂ : Travel direction of left front wheel A ₃ : Travel direction of right rear wheel A ₄ : Travel direction of left rear wheel C: Wheels P ₁ , P _{2, P} 3, the same common turning center point for _{P 4} L: the distance from the X axis of the wheel _{P 1, P 2, P 3} , P 4 O: center point to the wheels _{P 1, P 2, P 3} , P 4 P ₁ : Right front wheel P ₂ : Left front wheel P ₃ : Right rear wheel P ₄ : Left rear wheel R: Steering command value (X coordinate of the same common turning center point)
m: Steering command value (Y coordinate of the same common turning center point)
W: Distance of wheels P ₁ , P ₂ , P ₃ , P ₄ from Y coordinate axis X: X coordinate axis Y: Y coordinate axis α ₁ : Steering angle α _{2 of} right front wheel: Steering angle α _{3 of} left front wheel: Right rear wheel Steering angle α ₄ : Steering angle ΔR, Δm of the left rear wheel: Micro steering command value

Claims (3)

In a steering control method for a four-wheel independently-steered vehicle in which the vehicle is driven while changing the steering mode, the right front wheel P ₁ and the left front wheel that are respectively positioned at the corners of the virtual quadrangle and are disposed on the vehicle body base and independently controlled. The center point O with respect to P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is taken as the coordinate origin, the line extending in the left-right direction of each wheel through the center point O is taken as the X coordinate axis, and passes through the center point O. A line extending in the front-rear direction of each wheel is defined as a Y coordinate axis, and the respective turning centers of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ required for turning the vehicle body base Let the point be the same common turning center point C, and the X and Y coordinates of the same common turning center point C be (R, m), and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P _4. , P ₃ from the X coordinate axis The distance is L, the distance from the Y coordinate axis of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ is W, and the X coordinate / Y of the same common turning center point C Using the coordinates (R, m) as steering command values R, m, the steering angles α ₁ , α ₂ , α ₃ of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ are described. , Α ₄ is expressed by the following steering constraint condition formula:

The steering command value m is changed from m ₁ to m _2, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels correspond to the steering command value m ₁ . the transition from the steering angle _{[α 1, α 2, α} 3, α 4] (m1), a steering angle corresponding to the steering command value _{m 2 [α 1, α 2} , α 3, α 4] to _(m2) in the process of, the steering command value m steering command value obtained by adding a small steering command value Delta] m to ₁ (m _{1 +} Δm) small transition steering angles that satisfy the steering constraint condition expression for _{[α 1, α 2, α} 3, α _{4] (m1 + Δm)} computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] (m1 + Δm) each steering angle alpha ₁ toward, alpha _2, alpha _3, changes the alpha ₄ Each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed to the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{( m1 + Delta] m)} after reaching, the steering command value (m 1 _{+ Δm)} further steering command value obtained by adding a small steering command value Δm (m 1 ₊ 2Δm) small transition steering angles that satisfy the steering constraint condition expression for [alpha ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + 2Δm)} , and each steering angle α ₁ , α ₂ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + 2Δm).} , Α ₃ , α ₄ are changed, and thereafter, similarly, a small transition steering angle [α ₁ , α that satisfies the steering constraint condition formula with respect to a steering command value (m ₁ + nΔm) obtained by sequentially adding a small steering command value Δm. ₂ , α ₃ , α ₄ ] _{(m1 + nΔm)} and calculate each steering angle α ₁ , α ₂ , α ₃ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(m1 + nΔm).} , repeatedly varying the alpha _4, the steering angle of each wheel alpha ₁ α _2, α _3, the steering angle alpha ₄ each _{[α 1, α 2, α} 3, α 4] each steering angle from _{(m1) [α 1, α} 2, α 3, α 4] to _(m2) A steering control method for a four-wheel independently-steered vehicle, characterized by being changed. In a steering control method for a four-wheel independently-steered vehicle in which the vehicle is driven while changing the steering mode, the right front wheel P ₁ and the left front wheel that are respectively positioned at the corners of the virtual quadrangle and are disposed on the vehicle body base and independently controlled. The center point O with respect to P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is taken as the coordinate origin, the line extending in the left-right direction of each wheel through the center point O is taken as the X coordinate axis, and passes through the center point O. A line extending in the front-rear direction of each wheel is defined as a Y coordinate axis, and the respective turning centers of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ required for turning the vehicle body base Let the point be the same common turning center point C, and the X and Y coordinates of the same common turning center point C be (R, m), and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P _4. , P ₃ from the X coordinate axis The distance is L, the distance from the Y coordinate axis of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ is W, and the X coordinate / Y of the same common turning center point C Using the coordinates (R, m) as steering command values R, m, the steering angles α ₁ , α ₂ , α ₃ of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ are described. , Α ₄ is expressed by the following steering constraint condition formula:

The steering command value R is changed from R ₁ to R _2, and the steering angles α ₁ , α ₂ , α ₃ , α ₄ of the wheels correspond to the steering command value R ₁ . Transition from each steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _(R1) to the steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _(R2) corresponding to the steering command value R _2. in the process of, steering command value steering command value obtained by adding a small steering command value [Delta] R to R ₁ (R _{1 +} ΔR) small transition steering angles that satisfy the steering constraint condition expression for _{[α 1, α 2, α} 3, α _{4] (R1 + ΔR)} computes its small transition steering angles _{[α 1, α 2, α} 3, α 4] each steering angle alpha ₁ toward the _{(R1 + ΔR), α 2} , α 3, changes the alpha ₄ Each steering angle α ₁ , α ₂ , α ₃ , α ₄ is changed to the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{( R1 +} After reaching the _{[Delta] R),} the steering command value (R 1 ₊ ΔR) further steering command value obtained by adding a small steering command value ΔR (R 1 ₊ 2ΔR) small transition steering angles that satisfy the steering constraint condition expression for [alpha ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR)} , and each steering angle α ₁ , α ₂ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR).} , Α ₃ , α ₄ are changed, and thereafter, similarly, the small transition steering angle [α ₁ , α satisfying the steering constraint condition expression with respect to the steering command value (R ₁ + nΔR) obtained by sequentially adding the small steering command value ΔR. ₂ , α ₃ , α ₄ ] _{(R1 + nΔR)} and calculate each steering angle α ₁ , α ₂ , α ₃ toward the minute transition steering angle [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1 + nΔR).} , repeatedly varying the alpha _4, the steering angle of each wheel alpha ₁ α _2, α _3, the steering angle alpha ₄ each _{[α 1, α 2, α} 3, α 4] (R1) each steering angle from _{[α 1, α 2, α} 3, α 4] to _(R2) A steering control method for a four-wheel independently-steered vehicle, characterized by being changed. In a steering control method for a four-wheel independently-steered vehicle in which the vehicle is driven while changing the steering mode, the right front wheel P ₁ and the left front wheel that are respectively positioned at the corners of the virtual quadrangle and are disposed on the vehicle body base and independently controlled. The center point O with respect to P ₂ , the right rear wheel P ₃ , and the left rear wheel P ₄ is taken as the coordinate origin, the line extending in the left-right direction of each wheel through the center point O is taken as the X coordinate axis, and passes through the center point O. A line extending in the front-rear direction of each wheel is defined as a Y coordinate axis, and the respective turning centers of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ required for turning the vehicle body base Let the point be the same common turning center point C, and the X and Y coordinates of the same common turning center point C be (R, m), and the left and right front wheels P ₂ and P ₁ and the left and right rear wheels P _4. , P ₃ from the X coordinate axis The distance is L, the distance from the Y coordinate axis of the left / right front wheels P ₂ , P ₁ and the left / right rear wheels P ₄ , P ₃ is W, and the X coordinate / Y of the same common turning center point C Using the coordinates (R, m) as steering command values R, m, the steering angles α ₁ , α ₂ , α ₃ of the right front wheel P ₁ , left front wheel P ₂ , right rear wheel P ₃ , left rear wheel P ₄ are described. , Α ₄ is expressed by the following steering constraint condition formula:

The steering command value m is changed from m ₁ to m ₂ , the steering command value R is changed from R ₁ to R _2, and the steering angles α ₁ , α ₂ , α ₃ and α ₄ are changed from the steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1) and (m1)} corresponding to the steering command values R ₁ and m ₁ to the steering command values R ₂ and m 1. _{In the} process of transitioning to steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2)} corresponding to ₂ , the small steering command values ΔR, Δm are added to the steering command values R ₁ , m _1. steering command value _{(R 1} + ΔR), a _{(m 1} + Δm) small transition steering angles that satisfy the steering constraint condition expression for _{[α 1, α 2, α} 3, α 4] (R1 + ΔR), (m1 + Δm) calculated, the micro transition steering angles _{[α 1, α 2, α} 3, α 4] (R1 + ΔR), towards the _{(m1 + Δm)} Each steering angle _{α 1, α 2, α 3} , by changing the alpha _4, each steering angle _{α 1, α 2, α 3} , α 4 are the small transition steering angles _{[α 1, α 2, α} 3, α 4 ] After reaching _{(R1 + ΔR), (m1 + Δm)} , steering command values (R ₁ + 2ΔR), ( R ₁ + ΔR), (m ₁ + Δm), and further adding minute steering command values ΔR, Δm to (R ₁ + ΔR), (m ₁ + Δm) m ₁ + 2Δm) the steering micro transition steering angles that satisfy the constraint condition expression for _{[α 1, α 2, α} 3, α 4] (R1 + 2ΔR), (m1 + 2Δm) computes its small transition steering angles [alpha ₁ , Α ₂ , α ₃ , α ₄ ] _{(R1 + 2ΔR), (m1 + 2Δm)} , the steering angles α ₁ , α ₂ , α ₃ , α ₄ are changed, and thereafter the minute steering command values ΔR, Δm are similarly changed. sequentially added steering command value _(R 1 + _nΔR), the steering relative to _(m 1 + _nΔm) Small transition steering angles that satisfy the constraint condition expression _{[α 1, α 2, α} 3, α 4] (R1 + nΔR), (m1 + nΔm) computes its small transition steering angles _{[α 1, α 2, α} 3, α 4 _{] (R1 + nΔR),} the _{(m1 + nΔm)} each steering angle alpha ₁ toward, α _2, α _3, by repeating the varying alpha _4, the steering angle alpha ₁ of the _{wheels, α 2, α 3, α} 4 The steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R1), (m1) are changed} to the respective steering angles [α ₁ , α ₂ , α ₃ , α ₄ ] _{(R2), (m2)} , respectively. A steering control method for a four-wheel independent steering vehicle.

Images