JP2011025845A - Steering control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control device for a vehicle, which accurately suppresses the deflection of the vehicle due to the inclination of a road surface while reducing a sense of incongruity given to a driver. <P>SOLUTION: The steering control device 1 for the vehicle includes a VGRS2 for adjusting a steering angle of the vehicle X by changing a steering gear ratio and an EPS3 for adjusting a steering torque of the vehicle X. In the steering control device 1 for the vehicle, an ECU4 controls both of the VGRS2 and the EPS3 based on a road camber to suppress the deflection for the vehicle X due to the road camber. Accordingly, for example, the steering control device can suppress a steering side from rotating due to a reaction force from a tire side or despite the driver's intention. This allows the driver to suitably travel on a road having the road camber via the same operations as those for traveling on an ordinary road. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle steering control device that controls steering of a vehicle so as to suppress the deflection of the vehicle due to road surface inclination.

  As a conventional vehicle steering control device, for example, the one described in Patent Document 1 is known. In this vehicle steering control device, when it is determined that the traveling road surface of the vehicle is a road surface slope (a cant road), the steering angle is controlled to ensure the straight running stability of the vehicle.

Japanese Patent Laid-Open No. 2006-240413

  Here, in the above-described vehicle steering control device, a steering angle adjusting means (such as a steering transmission ratio variable system) for adjusting the steering angle of the vehicle by changing the steering transmission ratio is used, and the vehicle A case where the deflection is suppressed is conceivable. However, in this case, since the steering wheel side (steering input shaft side) and the tire side (steering output shaft side) are relatively rotated, for example, if the vehicle driver does not hold the steering wheel, The handle side is rotated by the force, and there is a possibility that such deflection cannot be suppressed with high accuracy.

  On the other hand, in the above-described vehicle steering control device, there may be a case where the steering torque adjusting means (power steering system or the like) for adjusting the steering torque of the vehicle is used to suppress the deflection of the vehicle due to the road surface inclination. In this case, since both the steering wheel side and the tire side are rotated, the steering wheel side may be rotated against the driver's intention by the control amount, and the driver may feel uncomfortable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle steering control device capable of accurately suppressing vehicle deflection due to road surface inclination while reducing the uncomfortable feeling given to the driver.

  In order to achieve the above object, a vehicle steering control device according to the present invention is a vehicle steering control device for controlling steering of a vehicle so as to suppress the deflection of the vehicle due to a road surface inclination, and a steering transmission ratio. A steering angle adjusting means for adjusting the steering angle of the vehicle by changing the steering angle, a steering torque adjusting means for adjusting the steering torque of the vehicle, a steering angle adjusting means for suppressing deflection based on the road surface inclination, and And a control means for controlling both of the steering torque adjusting means.

  In this vehicle steering control device, both the steering angle adjusting means and the steering torque adjusting means are controlled so as to suppress the deflection of the vehicle due to the road surface inclination. Therefore, for example, it is possible to prevent the steering wheel side from rotating due to the reaction force from the tire side or the steering wheel side from rotating against the driver's intention. As a result, the driver can suitably travel on a road having a road surface slope by the same operation as traveling on a normal road. That is, according to the present invention, it is possible to accurately suppress the deflection of the vehicle due to the road surface inclination while reducing the uncomfortable feeling given to the driver.

  Here, the steering angle adjustment means may be a steering transmission ratio variable system, and the steering torque adjustment means may be a power steering system.

  The control means controls the steering angle adjusting means so as to cancel the yaw rate generated due to the road surface inclination, and controls the steering torque adjusting means so as to cancel the self-aligning torque generated due to the road surface inclination. It is preferable to do. In this case, the yaw rate generated due to the road surface inclination can be compensated by the steering angle adjusting means, and the self-aligning torque generated due to the road surface inclination can be compensated by the steering torque adjusting means.

  At this time, as a configuration that preferably exhibits the above-described effects, specifically, the control means estimates the load camber amount related to the road surface inclination, and calculates the load camber steering angle as a steering angle for canceling the yaw rate based on the load camber amount. In addition to controlling the steering angle adjusting means according to the load camber steering angle, the load camber steering torque as a steering torque for canceling the self-aligning torque is calculated based on the load camber amount, and according to the load camber steering angle. The reaction force steering torque is calculated as a steering torque that counteracts the reaction force generated by controlling the steering angle adjusting means, and the steering angle adjusting means is controlled according to the sum of the load camber steering torque and the reaction force steering torque. A configuration is mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress the deflection | deviation of the vehicle by a road surface inclination accurately, reducing the discomfort given to a driver | operator.

1 is a block diagram showing a vehicle steering control device according to an embodiment of the present invention. It is a figure for demonstrating the steering control apparatus for vehicles of FIG. It is a figure for demonstrating the load camber amount estimated with the steering control apparatus for vehicles of FIG. It is a figure which shows the two-wheel model for demonstrating the equation of motion of a vehicle. (A) is a perspective view for explaining a balance equation of force around the tire of the vehicle, (b) is a side view for explaining a balance equation of force around the tire of the vehicle, and (c) is around the tire of the vehicle. It is a top view for demonstrating the balance formula of this force.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a block diagram showing a vehicle steering control device according to an embodiment of the present invention. As shown in FIG. 1, the vehicle steering control device 1 according to the present embodiment is mounted on a vehicle X such as an automobile, and suppresses the deflection of the vehicle X due to a road camber (road slope, cant). The steering of the vehicle X is controlled. The vehicle steering control device 1 includes a VGRS (Variable Gear Ratio Steering: registered trademark) 2 as a steering angle adjusting means and an EPS (Electric Power Steering) 3 as a steering torque adjusting means.

  VRGS2 is a steering transmission ratio variable system that changes the steering gear ratio (steering transmission ratio) steplessly. The VGRS 2 relatively rotates the steering input shaft 12 and the steering output shaft 13 and adjusts the steering angle without the rotation (operation) of the handle 11 of the vehicle X. In other words, the VGRS 6 performs the steering angle control (actively) without depending on the input steering.

  The EPS 3 is a power steering system for adjusting the steering torque of the vehicle. The EPS 3 is of a rack and pinion type that is driven in response to the operation of the handle 11 by the driver (see FIG. 5A). Here, the EPS 3 is a rack coaxial type electric type. . The EPS 3 adjusts the steering torque with the rotation (operation) of the handle 11 of the vehicle X. That is, the EPS 3 executes steering torque control depending on (in synchronization with) the input steering.

  Further, the vehicle control steering apparatus 1 includes an ECU (Electronic Control Unit: control means) 4 as a controller constituted by, for example, a CPU, a ROM, a RAM, and the like. The ECU 4 includes a load camber amount estimating unit 4a that estimates a load camber amount as a force acting on the vehicle X due to the road camber, a load camber steering angle calculating unit 4b that calculates a load camber steering angle, which will be described later, A load camber steering torque calculator 4c for calculating the load camber steering torque, a steering angle controller 4d for controlling the steering angle by controlling the VGRS2, and a steering torque controller 4e for controlling the steering torque by controlling the EPS3. , Including.

  This ECU 4 is connected to a yaw rate sensor 5 that detects the yaw rate of the vehicle X, a left and right acceleration sensor 6 that detects the left and right acceleration (lateral G) of the vehicle X, and a vehicle speed sensor 7 that detects the vehicle speed of the vehicle X. Based on the output values from ˜7, both VGRS2 and EPS3 are controlled to be emphasized (details will be described later).

  Next, the operation of the above-described vehicle steering control device 1 will be described.

  Generally, when the vehicle X travels on a road where a road camber exists (hereinafter referred to as “road camber road”), yaw rate and self-aligning torque are generated in the vehicle X due to the road camber. Therefore, according to the ECU 4 of the present embodiment, when traveling on the road camber road, in principle, the VGRS 2 is controlled to cancel the yaw rate and the EPS 3 is controlled to cancel the self-aligning torque. Is suppressed.

但し、Ｙ：ロードキャンバ量、ｍ：車両Ｘの質量、Ｖ：車速、γ：ヨーレート、ｇ_ｙ：左右加速度。 Specifically, first, the load camber amount estimation unit 4a estimates the load camber amount based on the output values from the sensors 5-7. Here, as shown in FIG. 3, the vehicle X turning on the road camber road 10 at the yaw rate γ has the gravity mg of the vehicle X, the reaction force R from the road camber road 10, the centrifugal force mVγ, and the lateral acceleration g. _{Since y} acts, the load camber amount Y is estimated by the following equation (1).

Where Y: load camber amount, m: mass of the vehicle X, V: vehicle speed, γ: yaw rate, g _y : lateral acceleration.

但し、β：スリップ角、Ｉ_ｚ：車両Ｘの断面２次モーメント、ｌ_ｆ：重心から前輪軸中心までの距離、ｌ_ｒ：重心から後輪軸中心までの距離。 Here, the equation of motion considering the road camber when the vehicle X turns can be expressed by the following equation (2) as shown in the two-wheel model of FIG.

Where β: slip angle, I _z : sectional moment of inertia of vehicle X, l _f : distance from the center of gravity to the center of the front wheel axis, l _r : distance from the center of gravity to the center of the rear wheel axis.

但し、Ｃ_ｆ：前輪コーナリングフォース、δ：操舵角、Ｃ_ｆ：後輪コーナリングフォース。 Substituting F _yf and F _yr shown in the following equation (3) into the above equation (2) and rearranging, the following equation (4) is obtained.

Where C _f : front wheel cornering force, δ: steering angle, C _f : rear wheel cornering force.

Furthermore, the following equation (5) can be obtained by arranging under steady conditions (dβ / dt = dγ / dt = 0).

但し、β_δ：操舵により発生するスリップ角、β_ｃ：ロードキャンバにより発生するスリップ角、γ_δ：操舵により発生するヨーレート、γ_ｃ：ロードキャンバにより発生するヨーレート、Ａ：スタビリティファクタ。 Then, the above equation (5) can be transformed from the determinant theorem into the following equation (6). When the determinant of the following equation (6) is solved, the following equation (7) is obtained as an equation of motion. Will be.

Where β _δ : slip angle generated by steering, β _c : slip angle generated by road camber, γ _δ : yaw rate generated by steering, γ _c : yaw rate generated by road camber, A: stability factor.

但し、Ｔ_ｈ：操舵トルク、ξ：キャスタートレールξ_ｃ+ニューマチックトレールξ_ｎ、Ｎ_ｒ：比ストローク（ナットリード）、ｌ_ｋ：有効ナックルアーム長。 Moreover, the balance formula of the force around the tire of the vehicle X can be expressed by the following formula (8) from the balance of the force around the kingpin 14 shown in FIG. In the figure, θ _p is the pinion angle, x _r is the rack displacement, F _r is the rack axial force, T _s is the torque around the _king pin 14, and F _yf is the cornering force.

However, _{T h:} steering torque, ξ: caster trail ξ _c + pneumatic trail ξ _{n, N r:} ratio stroke (nut lead), _{l k:} effective knuckle arm length.

但し、τ_δ：操舵により発生するセルフアライニングトルク、τ_ｃ；ロードキャンバにより発生するセルフアライニングトルク。 If the relationship of the above equation (7) is substituted and arranged for this, the following equation (9) is obtained as a balance equation of the force around the tire.

Where τ _{δ is} a self-aligning torque generated by steering, τ _{c is} a self-aligning torque generated by a load camber.

Therefore, the load camber steering angle calculating section 4b, the yaw rate gamma _c is a control target value for canceling the load camber steering angle [delta] _c caused by the load camber, the above equation (7) below was obtained based on the equation ( 10). Then, by the steering angle control unit 4d, so that the steering angle is the target steering angle, i.e. a control command such that the load camber steering angle [delta] _c is output to VGRS2.

At the same time, the load camber steering torque calculation section 4c, the load camber steering torque T _c is a control target value for canceling the self-aligning torque tau _c caused by the load camber is obtained based on the above equation (9) It is calculated by the following equation (11).

Here, if VGRS2 is controlled to be loaded camber steering angle [delta] _c, the reaction force is generated in such control. Therefore, a reaction force steering torque T _δ (see the following equation (12)) as a steering torque that cancels this reaction force is output from the steering angle control unit 4d, and this reaction force steering torque T _δ is converted into the load camber steering torque T _c . The target steering torque T _h (= T _c + T _σ = τ _c + τ _δ ) is calculated by addition. Then, the steering torque control section 4e, the steering torque, so that the target steering torque Th, that is a control command such that the sum of the load camber steering torque T _c and reaction force steering torque T _[delta] is output to the EPS3 .

In the present embodiment, when the vehicle speed V is lower than a predetermined velocity V _alpha, dealing with the vehicle speed V as the predetermined speed V _alpha. This is to prevent the above expressions (10) to (12) from diverging due to V = 0.

  As described above, in the vehicle steering control device 1 of the present embodiment, both the steering angle and the steering torque are optimally controlled based on the information of the road camber so that the deflection of the vehicle X is suppressed. Therefore, the driver of the vehicle X can preferably travel on the road camber road 10 by the same operation as traveling on a normal road, and can comfortably drive without being aware of the road camber. As a result, according to the present embodiment, it is possible to accurately suppress the deflection of the vehicle X by the road camber while reducing the uncomfortable feeling given to the driver.

  In other words, in the present embodiment, the steering angle and the steering torque necessary for traveling on the road camber road 10 are calculated, and the VGRS 2 and EPS 3 are coordinated to control the vehicle X without changing the steering wheel angle, for example. It is possible to go straight on the road 10. Therefore, the driver does not need to perform a correction operation using the road camber, and the vehicle X can travel on the road camber road 10 with the same operation (sense) as when traveling on a road where no road camber exists.

By the way, in the conventional vehicle steering control device, the EPS 3 is feedback-controlled with the steering torque that takes into account only the yaw rate γ _{c of the} vehicle X generated by the road camber, and the oblique line maintenance running is performed. Therefore, the discomfort for the driver is not taken into consideration. Further, since the self-aligning torque τ _{c of the} vehicle X generated by the road camber is not taken into account, it may be difficult to suppress the deflection of the vehicle X in some cases.

  In this regard, in this embodiment, as described above, both the VGRS 2 and the EPS 3 are controlled so that the driver does not feel discomfort, and both the yaw rate and the self-aligning torque caused by the road camber are canceled out. Therefore, the above-described operational effect, that is, the effect of accurately suppressing the deflection of the vehicle X by the road camber while reducing the uncomfortable feeling given to the driver is effective.

In the present embodiment, as described above, the VGRS 2 is controlled so as to cancel the yaw rate γ _c generated due to the load camber, and the self-aligning torque τ _c generated due to the load camber is canceled. The EPS 3 is controlled as described above. That is, in the present embodiment, the yaw rate γ _c and the self-aligning torque τ _c generated in the vehicle X when traveling on the road camber road are compensated for by VGRS2 and EPS3, respectively.

  As mentioned above, although preferred embodiment of this invention was described, the steering control apparatus for vehicles which concerns on this invention is not restricted to the said steering control apparatus for vehicles 1 which concerns on embodiment, The summary described in each claim Of course, it may be modified within a range that does not change, or applied to other things.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering control apparatus, 2 ... VGRS (steering angle adjustment means), 3 ... EPS (steering torque adjustment means), 4 ... ECU (control means), X ... vehicle.

Claims (4)

A vehicle steering control device for controlling steering of a vehicle so as to suppress the deflection of the vehicle due to road surface inclination,
A steering angle adjusting means for adjusting a steering angle of the vehicle by changing a steering transmission ratio;
Steering torque adjusting means for adjusting the steering torque of the vehicle;
A vehicle steering control apparatus comprising: a control unit that controls both the steering angle adjusting unit and the steering torque adjusting unit so as to suppress the deflection based on the road surface inclination. The steering angle adjusting means is a steering transmission ratio variable system,
The vehicle steering control device according to claim 1, wherein the steering torque adjusting means is a power steering system.   The control means controls the steering angle adjusting means so as to cancel the yaw rate generated due to the road surface inclination, and also adjusts the steering torque so as to cancel self-aligning torque generated due to the road surface inclination. The vehicle steering control device according to claim 1 or 2, wherein the means is controlled. The control means includes
Estimating the amount of road camber related to the road slope,
A load camber steering angle as a steering angle for canceling the yaw rate is calculated based on the load camber amount, and the steering angle adjusting means is controlled according to the load camber steering angle.
A reaction force generated by calculating a load camber steering torque as a steering torque for canceling the self-aligning torque based on the load camber amount and controlling the steering angle adjusting means according to the load camber steering angle. 4. The vehicle according to claim 3, wherein a reaction force steering torque is calculated as a steering torque for canceling out the control, and the steering angle adjusting means is controlled in accordance with a sum of the load camber steering torque and the reaction force steering torque. Steering control device.

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