JP4024574B2 - Vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle control device that automatically suppresses or mitigates yaw angle movement of a vehicle that occurs due to a disturbance when the vehicle is to travel straight.
Therefore, the present invention is very useful for sufficiently ensuring the straight running stability of the vehicle.
The vehicle control device includes a power steering device in a broad sense including a so-called steering control device such as a well-known VGRS that intervenes in the steering angle operation of the driver.
[0002]
[Prior art]
FIG. 6 illustrates a control block diagram exemplifying a conventional processing execution procedure for the ACT command angle δ1. The ACT command angle δ1 has been conventionally used as a correction amount for the actual steering angle of the front wheels for the purpose of automatically suppressing or mitigating the yaw angle motion of the vehicle that occurs due to disturbance.
[0003]
In substantially the center of the vehicle state estimating portion in FIG. 6, on the basis of the steering angle theta _H and the vehicle speed V of the steering wheel of the measured vehicle (steering wheel), the yaw rate r of the vehicle target value r _n and the vehicle body of A target value α _n of the side slip angle α is estimated. The yaw angular velocity r of the vehicle and the side slip angle α of the vehicle body are separately measured, and the ACT command angle δ1 is calculated based on the following equation (1). As a result, the actual rudder angle δ of the front wheels is automatically adjusted. As a result, the unnecessarily yaw angle motion that needs to be reduced that occurs due to disturbance is moderated to some extent.
[Expression 1]
δ1 = g1 (r _n −r) + g2 (α _n −α) (1)
[0004]
[Problems to be solved by the invention]
The above formula (1) is highly versatile and has a relatively wide range of application. However, under certain special circumstances, it is not always possible to sufficiently suppress the yaw angular motion more than necessary due to disturbance. It was revealed by an experiment that we conducted.
For example, in particular, when traveling straight at high speed, the calculation accuracy for the correction amount (ACT command angle δ1) is insufficient, and therefore the conventional method for calculating the correction amount based on the above equation (1) is adopted. It has not been easy to sufficiently realize vehicle motion performance having robust straight running stability.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to realize a sufficiently stable vehicle motion performance having a robust straight running stability.
[0006]
[Means for Solving the Problem, Action, and Effect of the Invention]
In order to solve the above problems, the following means are effective.
That is, the first means detects the yaw motion of the vehicle by detecting the yaw angular velocity r and the side slip angle α generated in the vehicle, and outputs the steering angle command value δ1 that acts to suppress or mitigate the yaw motion. In a vehicle control device that calculates based on the angular velocity r and the side slip angle α and outputs the steering angle command value δ1 to the power steering device that assists the steering mechanism of the vehicle, steering for driving the vehicle straight (straight forward steering) ) Is calculated, and the steering angle command value is calculated using the corrected steering angle δ0. The correction steering angle δ0 acts to suppress or mitigate the yaw motion generated based on the disturbance. A correction steering angle calculation means for correcting δ1 and outputting it to the power steering apparatus is provided.
[0007]
Needless to say, if yaw motion occurs in the vehicle while the driver is performing straight steering (neutral steering) as described above, the cause of the yaw motion is disturbance. This conclusion can be easily derived from the equation of motion related to the yaw motion of the vehicle. Examples of such disturbances include a cross wind acting on the vehicle body.
[0008]
On the other hand, if the curvature radius of the yaw motion when the vehicle is turning in a steady circle is ρ, it is known that the actual steering angle δ of the vehicle at this time is given by the following equation (2).
[Expression 2]
ρ = V / r = (1-AV ² ) L / δ (2)
Here, V, r, and δ are the vehicle speed, the yaw angular velocity, and the actual steering angle of the front wheels, respectively, and L is the wheel base of the vehicle. Furthermore, the constant A is a vehicle stability factor (constant), and is given by the following equation (3).
[Equation 3]
_{A = m (L r K r} -L f K f) / (2L 2 K r K f) ... (3)
(Explanation of constants)
m ... weight L _f ... distance L _r ... distance K _f ... tire cornering power of one wheel per wheel K _r ... rear wheel of one wheel per tire between the vehicle center of gravity and a rear axle between the vehicle center of gravity and a front axle of the vehicle Cornering power These relationships are described in, for example, “Automotive Movement and Control (Sankaido): Issued April 15, 2001, Fourth Print”.
[0009]
From the above relationship, when the yaw angular velocity r based on the disturbance is detected during straight-ahead steering (neutral steering), as can be seen from the above equation (2), the following equation (4) or the following equation (5 It can be seen that the yaw angular velocity (r) based on the above disturbance can be suppressed without excess or deficiency at the counterclockwise yaw angular velocity (−r) that can be generated based on the actual steering angle δ0 given by
[Expression 4]
δ0 = L (AV ² −1) r / V (4)
[Equation 5]
δ0 = L (AV ² −1) a / V ² (5)
However, “ρ = V ² / a” was used here. The denominator a is the lateral acceleration acting on the vehicle.
[0010]
That is, when the yaw angular velocity r based on the disturbance is detected during straight-ahead steering (neutral steering), the above equation (4) or (5) is used instead of the correction amount δ1 of the above equation (1). It can be seen that the yaw motion of the vehicle can be suppressed by automatically applying so-called counter steering using the given steering angle δ0.
[0011]
Further, based on the steering rudder angle theta _H and the steering angular velocity omega _H, etc., straight steering may be determined whether (neutral steering holding) is performed. As other physical quantities for determining the straight-ahead steering, for example, a steering torque τ, a time differential value dτ / dt of the steering torque, and the like can be used.
Further, the determination as to whether or not the driver is performing steering (straight-ahead steering) for moving the vehicle straight may be a probabilistic determination that is often used in, for example, fuzzy control theory. By introducing these control methods, it is possible or easy to realize a natural steering feeling with less discomfort around straight-ahead steering.
[0012]
With the above configuration and operation, it is possible to realize sufficiently stable vehicle motion performance having robust straight-line stability. Therefore, according to the above-described means, it is possible to reduce altitude or delicate steering operation required by the driver when the vehicle is affected by disturbance (such as a crosswind or a lateral inclination of the road surface).
These actions and effects are particularly effective when the vehicle speed V is high, as can be seen from the above equations (4) and (5).
[0013]
As an application target system in which the present invention can be used, for example, a steer-by-wire system, an EPS + VGRS type system exemplified in an example described later, or a general conventional type (1 A motor EPS type) electric power steering device or the like is conceivable. In particular, a steer-by-wire system or an EPS + VGRS type system is more preferable as an application target system to be selected from the viewpoint that a power steering apparatus with a more natural steering feeling can be easily configured.
This is because the steer-by-wire system and EPS + VGRS type system in which the steering angle and the actual steering angle are not directly connected (one-to-one correspondence) are driven and controlled by only one electric motor. This is because it is relatively easy to eliminate, reduce, or adjust (tune) the uncomfortable feeling associated with steering such as a neutral steering rudder, as compared with the steering device.
[0014]
Furthermore, an object detection means for detecting an obstacle or a moving body located around the vehicle is provided , and when the obstacle or the moving body is detected, the steering angle command value δ1 that is not corrected by the corrected steering angle δ0 is set to the power steering. Output to the device .
For example, as the object detection means, a radar or the like often used for active cruise control or the like can be used.
[0015]
For example, even if yaw motion occurs unexpectedly due to disturbance, the yaw acceleration generated at that time may work in a direction to avoid a collision with an obstacle or a moving body around the vehicle by chance. Therefore, in these cases, it is considered that it is not always desirable to perform the above correction automatically, that is, forcibly.
According to the onset bright, when the obstacle or the moving body is detected around the vehicle, the correction steering angle δ0 steering angle command value δ1 not corrected by is outputted, with respect to the obstacle or mobile driver The avoidance operation (emergency steering or the like) is prevented from being obstructed by the above-described operation for suppressing disturbance.
[0016]
The second means causes the first means described above, the lane recognition means for recognizing the lane markings of the lane during driving by image processing, by employing the correction steering angle [delta] 0, the vehicle lane straddling whether a lane straddling estimating means estimates provided, when it is estimated that lane crossing occurs due lane crossing estimation means outputs a steering angle command value δ1 not corrected by the correction steering angle δ0 to the power steering device Is to do.
For example, as the lane recognition means, an in-vehicle camera such as a CCD camera that is often used in a lane keeping support system or the like can be used.
[0017]
For example, even if yaw motion occurs unexpectedly due to disturbance, the direction in which the yaw acceleration generated at that time happens to maintain (support) the driving in the approximate center of the lane in which the vehicle is traveling. It may be possible to work. Therefore, in these cases, it is considered that it is not always desirable to perform the above correction automatically, that is, forcibly.
According to the second means of the present invention, the steering angle command value δ1 that is not corrected by the corrected steering angle δ0 is output when it is estimated that the lane crossing is generated by the lane crossing estimation means, so that the driver intends. A lane change that is not performed is prevented from being executed by the above-described operation for suppressing disturbance.
[0018]
In addition, the third means is configured such that when the absolute value of the correction steering angle δ0 or the related value of the absolute value exceeds a predetermined threshold value ε (> 0) in the first or second means described above, a disturbance is generated. The alarm means which outputs the message which calls the attention with respect to a driver | operator to a driver | operator is provided.
When a disturbance that causes yaw motion occurs during straight-ahead steering, the driver can be expected to reliably perform steering such as neutral rudder according to such a message, thus realizing more reliable vehicle control. be able to.
By the above means of the present invention, the above-mentioned problem can be effectively or rationally solved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on specific examples. However, the present invention is not limited to the following examples.
〔Example〕
1 and 2 are a physical perspective view of a vehicle control device according to an embodiment of the present invention and a logical hardware configuration diagram of the vehicle control device. Reference numeral 1 denotes a handle (steering wheel). Reference numeral 2 denotes an electronic control unit (ECU) on the EPS (electric motor / power steering device) side that is controlled based on the output (steering torque τ) of the torque sensor 6 and the like. The actuator 4 having a motor that directly acts on the motor is controlled.
[0020]
Reference numeral 3 denotes an ECU (electronic control unit) on the VGRS (variable gear ratio system) side that is controlled based on an output (steering angle θ _H ) of the steering angle sensor 7. Controls the actuator 5 having a motor acting on the steering shaft 9. The ECU 3 and the actuator 5 on the VGRS side constitute means for changing the steering gear ratio, which is the ratio of the steering angle (steering wheel angle) and the actual steering angle, depending on the situation in the middle of the steering system. An example of the description can be found in, for example, Japanese Laid-Open Patent Publication No. 11-49003: Vehicle Steering Device.
[0021]
FIG. 3 is a control block diagram of the vehicle control apparatus according to the present embodiment. The ECU 10 is for executing control of an ABS (anti-skid brake system) or the like. The ECU 2 for EPS is connected to the ECU 10 or ECU 3 for executing VGRS control by a CAN (controller area network). For example, various data for control such as the yaw angular velocity r of the vehicle, the lateral acceleration a of the vehicle, the steering angle θ _H of the steering wheel, the actual steering angle δ of the front wheel, the vehicle speed V, the steering torque τ, and the side slip angle α of the vehicle body. Share.
Further, the AFS control calculation unit 200 of FIG. 3 executes management of the main program (torque inertia compensation control / assist control / handle return control / damper compensation control / etc.) On the EPS side, and at the same time, the command value of the ACT angle command δ0 ″ is calculated. This command value δ0 ″ coincides with the correction amount δ0 when the driver performs the straight steering (neutral steering).
[0022]
FIG. 4 shows a control block diagram according to the embodiment of the present invention of the AFS control calculation unit 200 of FIG. The corrected rudder angle calculation unit 220 (corrected rudder angle calculation means) calculates the corrected rudder angle δ0 according to the equation (4). The straight steering accuracy calculation unit 210 receives the steering angle θ _H and the steering angular velocity ω _H that is a time differential value thereof, and calculates a weight G3 (= G1 × G2) using the maps 211 and 212. The following expressions (6) and (7) represent functions (f1, f2) represented by these maps.
[Formula 6]
G1 = f1 (θ _H ) (6)
[Expression 7]
G2 = f2 (ω _H ) (7)
Of course, these functions f1 and f2 may be expressed using mathematical expressions.
[0023]
These maps 211 and 212 have a symmetrical shape with respect to the vertical axis, with the intercept coordinates of the vertical axis indicating Gi = 1 (non-dimensional), having the minimum value 0 at both left and right ends. For example, a trapezoidal shape, a rectangular shape, a bowl shape, a bell shape, a substantially normal distribution shape, or the like can be used as this graph shape, and any shape can be used as long as it is substantially flat and decreases rapidly and monotonously toward ± ∞. The optimum shape of this graph can be determined empirically.
[0024]
Especially when a rectangle, it is not necessary to prepare a map virtually above the determination process of the rectilinear steering rudder present invention, independent variables theta _H of the functions f1, f2, the absolute value of omega _H Therefore, the process can be configured simply.
However, the determination of straight-ahead steering (neutral steering) does not necessarily have a clear standard, so it is more desirable to make a determination based on such fuzzy control theory. By introducing these control methods, it is possible or easy to realize a natural steering feeling with less discomfort around straight-ahead steering.
[0025]
Furthermore, the vehicle speed V may be taken into account when calculating the weight G3. That is, for example, the weight G3 may be calculated in the form of “G3 = G1 × G2 × f3 (V); 0 ≦ f3 (V) ≦ 1”. By using an appropriate monotonically increasing function as the function f3, it is possible to realize a vehicle motion characteristic having robust straight-line stability in the high speed region, and in the low speed region, the steering feeling that is almost the same as the conventional one. Can be obtained.
The correction angle δ1 at the lower right in FIG. 4 indicates a correction value calculated according to the conventional control method shown in FIG.
[0026]
FIG. 5 is a flowchart illustrating the control processing execution procedure of the weight control unit 230 of FIG. In this flowchart, first, in step 510, the weight G3 and the command signals S1 and S2 are input. The first value of the command signal S 1, the object detecting means of the present invention, is when the obstacle or the moving body is detected in S1 = 1, in other cases is set to S1 = 0.
The same applies to the second command signal S2, and this value is set to S2 = 1 when it is estimated that the lane stride estimating means of the present invention will cause a lane stride, and to S2 = 0 in other cases. Is set.
[0027]
In step 520, the logical sum of the command signals S1 and S2 is calculated and stored in the variable S3. Steps 540, 550, and 560 represent assignment statements relating to the weights G3 ′ and G4, respectively.
For example, according to the control processing execution procedure of the weight control unit 230 as described above, the correction values δ0 ′ and δ1 ′ of FIG. 4 are calculated as the following equations (8) and (9).
[Equation 8]
δ0 ′ = δ0 × (G3 × S3),
S3 = (1-S1) × (1-S2) (8)
[Equation 9]
δ1 ′ = δ1 × {1- (G3 × S3)} (9)
[0028]
The value of the signal S3 is normally 1 except in exceptional cases where an obstacle is detected or a lane crossing is likely to occur.
Accordingly, the value of the following equation (10) that is finally calculated as the command value δ0 ″ of the ACT angle command is the value during straight steering (when G3≈1) due to the action of the straight steering accuracy calculation unit 210 described above. This substantially coincides with the value of δ0 in the above equation (4).
[Expression 10]
δ0 ″ = δ0 ′ + δ1 ′ (10)
[0029]
In addition, when steering is being performed dynamically such as when cornering is performed, the value of G3 is substantially close to 0. In these cases, the correction value δ1 calculated by the conventional method is Adopted.
In addition, even when intermediate or transitional steering is performed, such as a slight swing near the neutral point, for example, in the vicinity of the neutral point, the optimization or optimization of the above functions f1 and f2 Since a suitable value or an optimum value is set as the command value δ0 ″ of the finally output ACT angle command, a natural steering feeling can be realized.
[0030]
For example, with the configuration as described above, it is possible to realize sufficiently stable vehicle motion performance having robust straight running stability. Therefore, according to the above-described embodiment, it is possible to reduce the altitude or subtle steering operation required by the driver when the vehicle is affected by disturbance (such as a crosswind or a lateral inclination of the road surface).
[0031]
In the above-described embodiment, an EPS (electric motor / power steering device) that controls the actuator 4 having a motor that directly acts on the steering rack 8 and a VGRS that controls the actuator 5 that has a motor that acts on the steering shaft 9 ( A vehicle control device configured to assist control of the steering mechanism by combination with a variable gear ratio system) is exemplified, but there are other target systems to which the present invention can be applied, for example, a steer-by-wire system, The present invention can also be applied to a vehicle having a general conventional (one-motor EPS type) electric power steering device that is most widely used at present.
[0032]
However, in the steer-by-wire system and EPS + VGRS type systems such as the above embodiment, there are wires (control / drive wiring) intervening, or VGRS actuators intervene closer to the handle side than the torque sensor. Since the system configuration is adopted, the steering wheel is not directly connected to the tire (actual steering angle). Therefore, in these systems, the degree of freedom of the steering system regarding the transmission of the steering torque is ensured more than that of the conventional electric power steering device driven and controlled by only one electric motor. It is easy to eliminate, reduce, or adjust the uncomfortable feeling associated with steering at the time (neutral steering, etc.).
[0033]
[Modification]
In the above embodiment, the equation (4) is used in the corrected steering angle calculation unit 220 in FIG. 4, but the above equation (5) may be used instead of the equation (4). In this case, the lateral acceleration a acting on the vehicle may be input instead of the yaw angular velocity r, or the lateral acceleration a may be obtained according to the following equation (11).
[Expression 11]
a = Vr (11)
[0034]
In the case of using the alarm means of the present invention in the configuration of FIG. 4, an alarm message may be output when “δ0 ≧ ε1”, “δ0 ′ ≧ ε2”, “δ0 ″ ≧ ε3”, or the like. Here, ε1, ε2, and ε3 are predetermined appropriate constants. According to such means, the driver can be alerted when a non-small disturbance occurs, and at the same time, the output of the warning message is suppressed when a relatively small disturbance occurs. .
[0035]
In addition, the stability factor (constant A) in Equation (3) can be considered to be almost unchanged, but the stability factor A changes with changes in the weight of the vehicle and the position of the center of gravity. That is, the stability factor A varies depending on the number of passengers, the loaded load, the installed equipment weight, and the like. In order to cope with these changes, it is effective to take a measure such as providing a weighing scale for each vehicle, each axle, or each wheel. According to such means, since the variation of the total weight of the vehicle and the position of the center of gravity can be accurately determined, the accuracy of the stability factor A can be greatly improved in real time. Alternatively, the correction steering angle δ0 can be calculated with higher accuracy using the equation (5).
[Brief description of the drawings]
FIG. 1 is a physical perspective view of a vehicle control apparatus according to an embodiment of the present invention.
FIG. 2 is a logical hardware configuration diagram of a vehicle control device according to an embodiment of the present invention.
FIG. 3 is a control block diagram of the vehicle control device according to the embodiment of the present invention.
4 is a control block diagram according to an embodiment of the present invention of the AFS control calculation unit 200 of FIG.
FIG. 5 is a flowchart illustrating a control processing execution procedure of the weight control unit 230 in FIG. 4;
FIG. 6 is a control block diagram exemplifying a conventional calculation processing execution procedure for an ACT command angle δ1.
[Explanation of symbols]
1 ... Steering wheel (steering wheel)
2… EPS side ECU
3 ... ECU on the VGRS side
DESCRIPTION OF SYMBOLS 4 ... EPS side actuator 5 ... VGRS side actuator 6 ... Torque sensor 7 ... Steering angle sensor 8 ... Steering rack 9 ... Steering shaft 10 ... ECU for brake control
DESCRIPTION OF SYMBOLS 200 ... AFS control calculation part 210 ... Straight steering accuracy calculation part 220 ... Correction steering angle calculation part (correction steering angle calculation means)
230 ... Weight control unit V ... Vehicle speed r ... Vehicle yaw angular velocity α ... Side slip angle of vehicle body δ ... Actual steering angle (front wheel)
n: Subscript indicating target value δ0: ACT command angle δ1: ACT command angle (conventional part)
theta _H ... steering angle omega _H ... handle angular velocity S1 ... first command signal S2 ... second command signal Gi ... weight of the handle (0 ≦ Gi ≦ 1,1 ≦ i ≦ 4)

Claims (3)

The yaw motion of the vehicle is detected by detecting the yaw angular velocity r and the side slip angle α generated in the vehicle, and the steering angle command value δ1 that acts to suppress or mitigate the yaw motion is used as the steering angle command value δ1. In the vehicle control device that calculates based on the angle α and outputs the steering angle command value δ1 to the power steering device that assists the steering mechanism of the vehicle,
When it is assumed that the driver is performing steering for driving the vehicle straight (straight-ahead steering), a corrected steering angle δ 0 that acts to suppress or mitigate the yaw motion generated based on disturbance is calculated. A correction steering angle calculation means for correcting the steering angle command value δ1 using the correction steering angle δ0 and outputting the correction steering angle command value δ1 to the power steering device.
Furthermore, it has an object detection means for detecting an obstacle or a moving body located around the vehicle,
When the obstacle or the moving body is detected , the vehicle control device outputs the steering angle command value δ1 that is not corrected by the corrected steering angle δ0 to the power steering device. Lane recognition means for recognizing the lane marking of the running lane by image processing;
Lane crossing estimating means for estimating whether or not the vehicle crosses the lane by adopting the corrected steering angle δ0 ,
When it is estimated that lane crossing occurs by the lane crossing estimation means,
The vehicle control device according to claim 1 , wherein the steering angle command value δ1 that is not corrected by the corrected steering angle δ0 is output to the power steering device. Alarm means for outputting a message to the driver to call attention to the disturbance when the absolute value of the corrected steering angle δ0 or a related value of the absolute value exceeds a predetermined threshold ε (>0); The vehicle control device according to claim 1 , wherein the vehicle control device is provided.

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