JP2008074185A - Vehicle motion control method and vehicle motion controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve control precision of a yaw rate without an increase in costs and an uncomfortable feeling in driving. <P>SOLUTION: A vehicle motion controller comprises a yaw rate sensor for detecting a yaw rate detection value γ; an integrator 102j for estimating a yaw rate estimation value γhat on the basis of a yaw angle acceleration estimation value dγhat; a yaw angle acceleration estimation unit 102 for estimating the estimation value dγhat on the basis of a yaw rate operation quantity, a yaw rate deviation (γ-γhat) that is a deviation between the detection value γ and the estimation value γhat, and an integrated value of the deviation (γ-γhat); and an F/B instruction unit 103 for computing the yaw rate operation quantity (feedback front wheel steering angle operation quantity δfFB, a feedback rear wheel right and left driving force difference operation quantity uFB) satisfying a target response of the yaw rate detection value γ on the basis of the a target yaw rate tγ, the yaw rate detection value γ and the estimation value dγhat. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention belongs to the technical field of a vehicle motion control method and a vehicle motion control device for performing yaw rate control of a vehicle by a yaw rate operation amount.

  As a conventional vehicle motion control device, in Cited Document 1, the yaw angular acceleration is estimated from the difference between two lateral acceleration sensors, and the rear wheel is steered in proportion to the yaw angular acceleration, thereby controlling the yaw rate control accuracy. Techniques for increasing the frequency are known.

Here, as another estimation method of the yaw angular acceleration, the cited document 2 describes a method for estimating the yaw rate detection value by the yaw rate sensor based on the time difference. Also, in Cited Document 3, the yaw angular acceleration estimated using a filter based on the dynamic characteristics of the control target is inputted in proportion to the deviation between the detected yaw angular acceleration value and the estimated yaw angular acceleration value. And a method of correcting it is described.
JP-A-6-65454 JP 2002-331951 A Japanese Patent Laid-Open No. 2-151469

However, the above prior art has the following problems.
In the technique described in the cited document 1, since two lateral acceleration sensors are used for the estimation of the yaw angular acceleration, it is disadvantageous in terms of cost and layout including wiring, etc. Since yaw angular acceleration is estimated by calculation, controllability may be deteriorated due to a numerical calculation error.

  In the technique described in the cited document 2, there is a possibility that noise included in the yaw rate detection value is amplified, chattering of the yaw rate due to noise occurs, and driving may feel uncomfortable. Further, since the estimation is based on the yaw rate detection value, the estimation of the yaw angular acceleration with respect to the control operation amount is delayed, and the control accuracy may be deteriorated.

  In the technique described in the cited document 3, estimation delay of the yaw angular acceleration with respect to the control operation amount can be avoided, but correction of the yaw angular acceleration estimated value proportional to the deviation between the yaw angular acceleration detected value and the yaw angular acceleration estimated value is possible. Therefore, the yaw angular acceleration estimated value does not converge to the true value due to the yaw angular acceleration detection error or disturbance, and the control accuracy may deteriorate.

  The present invention has been made paying attention to the above-mentioned problems, and its object is to provide a vehicle motion control method and a vehicle capable of improving the control accuracy of the yaw rate without increasing costs or feeling uncomfortable during driving. It is to provide a motion control device.

In order to achieve the above object, the present invention provides:
In a vehicle motion control device that performs yaw rate control of a vehicle based on a yaw rate operation amount,
A yaw rate detection means for detecting the yaw rate;
Yaw rate estimating means for estimating the yaw rate based on the yaw angular acceleration estimated value;
A yaw angular acceleration estimating means for estimating the yaw angular acceleration based on the yaw rate manipulated variable, a yaw rate deviation that is a deviation between the yaw rate detected value and the yaw rate estimated value, and an integral value of the yaw rate deviation;
Feedback manipulated variable calculation means for calculating a yaw rate manipulated variable that satisfies the target response of the yaw rate based on the target yaw rate, the yaw rate detection value, and the yaw angular acceleration estimated value;
It is characterized by providing.

In the vehicle motion control device of the present invention, yaw rate acceleration can be estimated by diverting the yaw rate detection means for controlling the yaw rate. Therefore, the control accuracy of the yaw rate is improved without causing an increase in cost, and the driver feels uncomfortable. Alleviated.
Further, since the yaw angular acceleration is estimated from the yaw rate manipulated variable, the yaw rate deviation that is the deviation between the yaw rate detected value and the yaw rate estimated value, and the integrated value of this yaw rate deviation, Proportional / integral compensation prevents estimation delays. Therefore, as the estimation accuracy of the yaw rate estimation value is improved, the estimation accuracy of the yaw angular acceleration is also improved, so that the yaw rate control accuracy is further increased, and driving discomfort is further suppressed.
As a result, it is possible to improve the control accuracy of the yaw rate without increasing costs and feeling uncomfortable with driving.

  Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

First, the configuration will be described.
[overall structure]
FIG. 1 is a configuration diagram of an electric vehicle to which the vehicle motion control device of the first embodiment is applied.
The electric vehicle of the first embodiment includes electric motors 3RL and 3RR as driving force generation sources, and the rotation shafts of the motors 3RL and 3RR are rear wheels of the electric vehicle via the speed reducers 4RL and 4RR ( Drive wheels) are connected to 2RL and 2RR. The output characteristics of the two motors 3RL and 3RR, the reduction ratios of the two speed reducers 4RL and 4RR, and the radii of the two wheels are all the same.

  Each of the motors 3RL and 3RR is a three-phase synchronous motor in which a permanent magnet is embedded in a rotor. Torque command values tTRL (left rear wheel) and tTRR (right) are received by the drive circuits 5RL and 5RR that control power transfer with the lithium ion battery 6 from the integrated controller 30 with the power running and regenerative torque of the motors 3RL and 3RR. Adjust to match the rear wheels. The drive circuits 5RL and 5RR transmit the output torque of each motor 3RL and 3RR and the motor rotation speed detected by a rotation position sensor (not shown) attached to the motor rotation shaft to the integrated controller 30, respectively.

  The front wheels (steering wheels) 2FL and 2FR are mechanically steered via the steering gear 14 by the rotational movement of the steering wheel 11 operated by the driver, and the steering gear 14 is entirely driven by the auxiliary steering motor 12. Auxiliary steering is performed by displacing in the vehicle width direction. That is, the steering angles of the front wheels 2FL and 2FR are the sum of the main steering angle by the steering wheel 11 and the auxiliary steering angle by the auxiliary steering motor 12. The front wheel rudder angle is controlled to match the target front wheel rudder angle transmitted by the integrated controller 30 by adjusting the output of the auxiliary steering motor 12 by the control circuit 13. The front wheels 2FL and 2FR are equipped with rotation sensors 25 and 26 for detecting the rotation speed, and detect the respective rotation speeds and transmit them to the integrated controller 30.

  In addition, the integrated controller 30 includes an accelerator opening signal APO detected by the accelerator pedal sensor 23, and a rotation angle signal STR of the steering wheel 11 detected by the steering angle sensor 21 attached to the rotation shaft of the steering wheel 11. The yaw rate signal γ detected by the yaw rate sensor (yaw rate detection means) 8, the longitudinal acceleration signal ax and the lateral acceleration signal ay detected by the acceleration sensor 28 attached to the center of gravity position, and also attached to the center of gravity position. A vehicle body side slip angle signal β output from the vehicle body side slip angle sensor (vehicle body side slip angle detecting means) 29 is input.

[Vehicle motion control processing]
FIG. 2 is a flowchart showing the flow of the vehicle motion control process calculated by the integrated controller 30 of the first embodiment. Each step will be described below. The integrated controller 30 includes peripheral components such as a RAM / ROM in addition to the microcomputer, and executes the flowchart of FIG. 2 at regular intervals, for example, every 5 ms.

  In step S100, sensor signals and received signals from the drive circuits 5RL and 5RR are stored in RAM variables, and the process proceeds to step S101. Specifically, the accelerator opening signal is stored in a variable APS (unit is%, and 100% when fully opened), and the rotation angle signal of the steering wheel 11 is a variable STR (counterclockwise is positive). , The vehicle body yaw rate signal is stored in variable γ (the direction when turning left is positive), the vehicle body lateral acceleration signal is stored in ay (left direction is positive), and the vehicle body longitudinal acceleration signal is stored in ax ( The vehicle's side slip angle signal is stored in β (counterclockwise is positive), and the rotation speed of each front wheel is NFL, NFR (the direction in which the vehicle moves forward is positive). To store. As for the signals received from the drive circuits 5RL and 5RR, the output torques of the motors 3RL and 3RR are stored in the variables TRL and TRR (the direction in which the vehicle is accelerated is positive), and the rotations of the motors 3RL and 3RR are rotated. The speed is stored in variables NRL and NRR (the direction in which the vehicle moves forward is positive).

In step S101, the vehicle speed V (unit is m / s, and the direction in which the vehicle moves forward is positive) is calculated by the following equation, and the process proceeds to step S102.
V = (NFL + NFR) x R / GG / 2
Where R is the wheel radius and GG is the reduction gear ratio.

In step S102, the wheel loads Zfl, Zfr, Zrl, Zrr of the four wheels are obtained from the following equations, and the process proceeds to step S103 (wheel load estimating means).
Zfl = Zf-ΔZd-2ΔZc ・ (Zf-ΔZd) / (Zf + Zr)
Zfr = Zf-ΔZd + 2ΔZc ・ (Zf-ΔZd) / (Zf + Zr)
Zrl = Zr + ΔZd-2ΔZc ・ (Zr + ΔZd) / (Zf + Zr)
Zrr = Zr + ΔZd + 2ΔZc ・ (Zr + ΔZd) / (Zf + Zr)
Zf = mgLr / L
Zr = mgLf / L
ΔZd = m ・ ax ・ hcg / 2L
ΔZc = m ・ ay ・ hcg / 2Lt
Here, Lt is half of the tread distance, and hcg is the height of the center of gravity. In the first embodiment, the description will be made ignoring the delay in load change due to the suspension, but the delay in load change may be considered.

  In step S103, the calculation shown in the yaw rate servo control calculation block diagram of FIG. 3 is performed, and this control process ends. Hereinafter, the yaw rate servo control calculation of the first embodiment will be described.

[Yaw rate servo control calculation]
The yaw rate servo control calculation block of FIG. 3 includes a target value calculation unit 100, a feedforward (F / F) command unit (feedforward manipulated variable calculation means) 101, a yaw angular acceleration estimation unit 102, and a feedback (F / B ) A command unit (feedback operation amount calculation means) 103 and a vehicle 104 are provided.

(Target value calculator)
The target value calculation unit 100 calculates the target driving force tFd from the vehicle speed V, the steering operation amount STR, and the accelerator opening APS, for example, using the target driving force map shown in FIG. 4, and the target lateral force shown in FIG. A target lateral force tY is calculated from the map, and a target yaw rate tγ is calculated from the target lateral force using the following equation.
tγ = tY / (m ・ V)

(F / F command section)
In the F / F command unit 101, the front wheel steering angle manipulated variable δfFF and the rear wheel left / right driving force operation which are given by feedforward so as to achieve both the target braking / driving force tFd and the target yaw rate tγ calculated by the target value calculating unit 100 The quantities uFFrl and uFFrr are calculated respectively.

First, in order to generate braking / driving force, for example, the target braking / driving force tFd is equally distributed to the left and right rear wheels as follows to obtain basic rear wheel driving force uFFrl0 (left rear wheel) and uFFrr0 (right rear wheel). .
uFFrl0 = uFFrr0 = tFd / 2 (1)

ここで、sはラプラス演算子、aは０以上１以下の分配係数である。 Next, the feedforward front wheel steering angle δfFF and the feedforward rear wheel driving force difference uFF that achieve the target yaw rate tγ, for example, the transfer function Qf (s, V) from the front wheel steering angle δf to the yaw rate, and the rear wheel left-right drive Using the transfer function Qu (s, V) from the force difference to the yaw rate and the transfer function D (s, V) indicating the normative response from the target yaw rate tγ to the yaw rate, the following equation is used.

Here, s is a Laplace operator, and a is a distribution coefficient of 0 or more and 1 or less.

よって、目標ヨーレートtγからヨーレートが、伝達関数D(s,V)で表される応答となる。ここで、分配係数aは、固定値としてもよいし、燃費や走行条件に応じて随時設定される値としてもよい。 When there is no modeling error or disturbance and the front wheel steering angle operation amount ΔfFF is realized without limitation, the transfer function from the target yaw rate tγ to the yaw rate is expressed by the following equation.

Therefore, the yaw rate from the target yaw rate tγ is a response represented by the transfer function D (s, V). Here, the distribution coefficient a may be a fixed value, or may be a value that is set as needed according to fuel consumption and driving conditions.

Feed forward rear wheel left and right driving forces uFFrl and uFFrr are expressed by the following equations.
uFFrl = uFFrl0-uFF
uFFrr = uFFrr0 + uFF

(F / B command section)
The F / B command unit 103 uses the target yaw rate tγ, the yaw rate, and the yaw angular acceleration estimated value dγhat estimated by the yaw angular acceleration estimation unit 102 to determine the feedback front wheel steering angle manipulated variable δfFB and the feedback rear wheel for yaw rate servo control. The left / right driving force difference manipulated variable uFB is calculated according to the block diagrams shown in FIGS.

A) Calculation of Feedback Front Wheel Steering Angle Manipulation Amount δfFB FIG. 6 is a block diagram of feedback front wheel steering angle manipulation amount computation of the first embodiment.
The control error calculation unit (first control error calculation unit) 200 calculates a control error (first control error) σf as represented by the following equation.

Here, ω is a response parameter determined by the reference response D (s, V). The normative response D (s, V) is expressed by the following equation.

If the control error σf is zero, from the equation (4), the relationship between the target yaw rate tγ and the yaw rate is as follows, which is consistent with the normative response expressed by the equation (5).

Further, since the first term of the equation (4) is the integral of the deviation between the target yaw rate tγ and the yaw rate, if the control error σf is zero, the steady deviation between the target yaw rate tγ and the yaw rate is theoretically zero.
Therefore, the front wheel steering angle F / B operation amount calculation unit (first yaw rate operation amount calculation unit) 201 calculates a feedback front wheel steering angle operation amount (first yaw rate operation amount) δfFB as a high gain switching operation amount as follows. Then, the control error is suppressed to near zero.

  Here, εf is a positive constant for preventing chattering, and Kf is a switching gain. The switching gain Kf is sufficiently large in consideration of disturbances and model errors, for example, the maximum value of the front wheel steering angle δf.

  In addition, this method is not model-based but refers to the detection or estimation value of the yaw rate and yaw angular acceleration dγ, and forcibly pushes the target yaw rate tγ, yaw rate, and yaw angular acceleration dγ into the desired relationship. Since there is no need to consider the time-varying or non-linearity of the controlled object, the control gain adaptation time for the gain schedule is not required.

B) Calculation of Feedback Rear Wheel Left / Right Driving Force Difference Operation Amount uFB FIG. 7 is a feedback rear wheel left / right driving force difference operation amount calculation block diagram of the first embodiment.
The control error calculation unit (second control error calculation unit) 300 calculates a control error (second control error) σu as represented by the following equation.

ただし、制御誤差σfのように目標ヨーレートtγとヨーレートの偏差の積分を含まないので、目標ヨーレートtγとヨーレートの定常偏差がゼロとなる保証はない。 If the control error σu is zero, the relationship between the target yaw rate tγ and the yaw rate is expressed by the following equation from equations (7) and (8), which is consistent with the normative response expressed by equation (5).

However, since the integration of the deviation between the target yaw rate tγ and the yaw rate is not included like the control error σf, there is no guarantee that the steady deviation between the target yaw rate tγ and the yaw rate is zero.

Then, in the driving force difference F / B operation amount calculation unit (second yaw rate operation amount calculation unit) 301, the feedback rear wheel left and right driving force difference operation amount (second yaw rate operation amount) is used as a high gain switching operation amount as follows. Calculate uFB and suppress the control error to near zero.

  Here, εu is a positive constant for preventing chattering, and Ku is a switching gain. Ku is sufficiently large in consideration of disturbances and model errors, for example, the maximum value of the rear wheel driving force difference.

Returning to FIG. 3, the feedback operation amount δfFB, uFB is added to the feedforward operation amount δfFF, uFFrl, uFFrr to calculate the front wheel steering angle operation amount δf and the rear wheel left / right driving force difference operation amount url, urr as follows. .
δf = δfFF + δfFB
url = uFFrl-uFB
urr = uFFrr + uFB

  The yaw angular acceleration estimation unit (yaw angular acceleration estimating means) 102 follows the block diagram shown in FIG. 8 from the front wheel steering angle command δf * (front wheel steering angle operation amount), the rear wheel left / right driving force difference command uy *, and the yaw rate. Then, the yaw angular acceleration estimated value dγhat is calculated.

  The yaw angular acceleration estimation block in FIG. 8 includes a tire lateral force yaw moment calculation unit (yaw moment manipulated variable estimation unit) 102a, a multiplier 102b, an adder 102c, a multiplier 102d, a difference unit 102e, and a multiplier. 102f, a multiplier 102g, an integrator 102h, an adder (yaw angular acceleration calculating unit) 102i, and an integrator (yaw rate estimating means) 102j.

The tire lateral force yaw moment computing unit 102a receives the front wheel steering command Δf * and outputs the yaw moment MY due to the tire lateral force.
The multiplier 102b receives the rear wheel driving force difference command uy * and outputs a value 2Ltuy * multiplied by 2Lt. Here, Lt is half the rear wheel tread width.
The adder 102c inputs the yaw moment MY and 2Ltuy * due to the tire lateral force, and outputs a value MY + 2Ltuy * obtained by adding the two.
The multiplier 102d receives MY + 2Ltuy * and outputs a base value dγhat0 of yaw angular acceleration obtained by multiplying 1 / Iz. Here, Iz is the yaw inertia around the center of gravity.

The comparator 102e receives the yaw rate detection value γ and the yaw rate estimation value γhat, and outputs a yaw rate deviation γ−γhat that is the difference between the two.
The multiplier 102f receives the yaw rate deviation γ-γhat and obtains a value h1 (γ-γhat) obtained by multiplying the variable h1.
The multiplier 102g receives the yaw rate deviation γ−γhat and outputs a value h2 (γ−γhat) obtained by multiplying the variable h2.
The integrator 102h receives h2 (γ−γhat) and outputs an integral value h2 (γ−γhat) / s multiplied by 1 / s.

The adder 102i inputs base values dγhat0, h1 (γ-γhat) and h2 (γ-γhat) / s of yaw angular acceleration, and outputs the sum of the input values as a yaw angular acceleration estimated value dγhat.
The integrator 102j receives the yaw angular acceleration estimated value dγhat and outputs a yaw rate estimated value γhat that is an integrated value multiplied by 1 / s.

Hereinafter, a yaw angular acceleration estimated value dγhat calculation method in the yaw angular acceleration estimation block will be described.
First, the rear wheel driving force difference command uy * is expressed by the following equation.

ここで、Lfは前輪軸から重心までの長さ、Lrは後輪軸から重心までの長さ、Ltは後輪トレッド幅の半分、Izは重心まわりのヨー慣性である。MYはタイヤ横力によるヨーモーメントを表す。 A linearly approximated relationship between the yaw rate γ, the tire lateral forces Yfl, Yfr, Yrl, Yrr of each of the four wheels and the rear wheel driving force difference uy is expressed by the following equation.

Here, Lf is the length from the front wheel axis to the center of gravity, Lr is the length from the rear wheel axis to the center of gravity, Lt is half the rear wheel tread width, and Iz is the yaw inertia around the center of gravity. MY represents yaw moment due to tire lateral force.

The tire lateral force is calculated by, for example, a tire characteristic map shown in FIG. 9 from the tire side slip angle and the load. Tire slip angle (left front βfl, right front βfr, left rear βrl, right rear βrr) is expressed by the following equation.

  Here, δr is the rear wheel steering angle, but in the first embodiment, no rear wheel steering is performed, so δr is set to zero.

Further, the wheel loads Zfl, Zfr, Zrl, Zrr of the four wheels are obtained by the following equations.
Zfl = Zf-ΔZd-2ΔZc ・ (Zf-ΔZd) / (Zf + Zr)
Zfr = Zf-ΔZd + 2ΔZc ・ (Zf-ΔZd) / (Zf + Zr)
Zrl = Zr + ΔZd-2ΔZc ・ (Zr + ΔZd) / (Zf + Zr)
Zrr = Zr + ΔZd + 2ΔZc ・ (Zr + ΔZd) / (Zf + Zr)
Zf = mgLr / L
Zr = mgLf / L
ΔZd = m ・ ax ・ hcg / 2L
ΔZc = m ・ ay ・ hcg / 2Lt
Here, L is the wheelbase length and hcg is the height of the center of gravity. Here, in the first embodiment, a delay in load change due to the suspension ignored may be taken into consideration.

  However, the calculation of the tire side force is not limited to this method, and instead of using the tire characteristic map, the relationship between the tire side slip angle and the tire force, which is linearly approximated near the tire side slip angle, is used. Even in the method of roughly estimating the yaw moment MY due to the tire lateral force, the estimated speed of the yaw angular acceleration is improved as compared with the conventional technique. Also, the wheel load may be substituted for the target values of longitudinal acceleration and lateral acceleration without using the acceleration sensor, and in this case, the acceleration sensor 28 may not be provided.

  Based on the tire lateral force and the rear wheel drive force difference command uy * shown above, the yaw angular acceleration base value dγhat0, which is the time derivative of the yaw rate, is calculated using equations (10) and (11). To do.

However, in actuality, the actual yaw angular acceleration and the base value dγhat0 of the yaw angular acceleration do not coincide with each other due to measurement errors of Lf, Lr, Lt, and Iz, linear approximation errors, actuator drive delay, and the like. Therefore, a correction value dγhatm of the yaw angular acceleration estimated value is calculated according to the deviation between the yaw rate detected value γ and the yaw rate estimated value γhat, as in the following equation.

  Here, h1 and h2 are variables indicating the correction speed. If h1 and h2 are increased, the estimation error is compensated faster, but chattering of the estimated value due to noise is likely to occur. Therefore, as shown in FIG. 10, h1 and h2 are set to larger values as the change in the target yaw rate tγ is larger and the response of the normative response is faster (the larger ω is).

Then, the sum of the base value dγhat0 of the yaw angular acceleration dγ and the correction value dγhatm of the yaw angular acceleration estimated value is set as the yaw angular acceleration estimated value dγhat as follows.
dγhat = dγhat0 + dγhatm

The yaw rate estimated value γhat is expressed by the following equation as an integral of the yaw angular acceleration estimated value dγhat.

  Therefore, since the equation (12) is in the form of a proportional / integral compensator of the deviation between the yaw rate detection value γ and the yaw rate estimation value γhat, the deviation of the yaw moment due to disturbance or modeling error is integrated and the yaw rate is compensated. The estimated value γhat is estimated with high accuracy.

However, although ignored in the first embodiment, dγhat0 may be calculated in consideration of a delay in the tire generation force with respect to the operation amount of the front wheel steering angle and the rear wheel left / right driving force difference.
In addition, in the calculation of dγhat0, the estimated speed of the yaw angular acceleration is improved with respect to the prior art only with either the front wheel steering angle or the rear wheel driving force difference.

Next, the operation will be described.
[Yaw rate control accuracy improvement effect]
In the vehicle motion control apparatus according to the first embodiment, the yaw angular acceleration estimated value dγhat is calculated using the yaw rate sensor 8 for yaw rate control, and therefore, the yaw angular acceleration is estimated from the difference between the two lateral acceleration sensors. As compared with the technique described in Japanese Patent Laid-Open No. 6-65454, it is possible to improve the control accuracy of the yaw rate without causing an increase in cost, and the uncomfortable feeling of driving is alleviated.

  In the first embodiment, the yaw angular acceleration estimation unit 102 determines the yaw angular acceleration base value dγhat0 based on the front wheel steering command δf * and the rear wheel driving force difference command uy *, the yaw rate detection value γ, and the yaw rate estimated value γhat. The sum of the yaw rate deviation h1 (γ-γhat), which is the deviation of the yaw rate, and the integrated value h2 (γ-γhat) / s of this yaw rate deviation is the yaw angular acceleration estimated value dγhat, and this yaw angular acceleration estimated value is integrated The yaw rate estimated value γhat is calculated.

  Therefore, from equation (12), the proportional and integral compensation of the deviation between the yaw rate detection value γ and the yaw rate estimation value γhat compensates for the yaw moment deviation due to disturbance, modeling error, etc., and the yaw rate estimation value γhat is accurate. Presumed. Further, the base value dγhat0 of the yaw angular acceleration has an effect of suppressing the estimated delay of the yaw angular acceleration with respect to the operation input.

  Therefore, as the estimation accuracy of the yaw rate estimated value γhat is improved, the estimation accuracy of the yaw angular acceleration estimated value dγhat is also improved, so that the yaw rate control accuracy is further increased and the uncomfortable feeling of driving is further suppressed.

  In Equation (12), the variables h1 and h2 are set to larger values as the change in the target yaw rate tγ is larger and the response of the norm response is faster (the larger ω is). When the yaw rate changes rapidly and the yaw angular acceleration increases, the estimation delay is suppressed. When the yaw rate changes slowly and the yaw angular acceleration dγ is small and easily affected by noise, the influence of noise is suppressed. .

  In the first embodiment, in the front wheel steering angle F / B operation amount calculation unit 201, the switching gain Kf of Equation (6) for calculating the feedback front wheel steering angle operation amount δfFB is sufficiently large, for example, set to the maximum value of the front wheel steering angle δf. Therefore, the control error σf converges near zero, and the yaw rate follows the target yaw rate tγ with a normative response, so that a smooth turning behavior can be provided to the driver. Further, since the actual yaw rate manipulated variable (front wheel steering angle δf) is not saturated with respect to the manipulated variable command value, the yaw angular acceleration estimating unit 102 determines the yaw angular acceleration estimated value dγhat based on the manipulated variable. The estimation accuracy can be improved.

  Further, in the driving force difference F / B operation amount calculation unit 301, the switching gain Ku of the equation (9) for calculating the feedback rear wheel left and right driving force difference operation amount uFB is sufficiently large, for example, to the maximum value of the rear wheel driving force difference. Thus, the control error σu converges to near zero, and the yaw rate follows the target yaw rate tγ with a normative response, so that a smooth turning behavior can be provided to the driver. Further, since the actual yaw rate manipulated variable (rear wheel left / right driving force difference) is not saturated with respect to the manipulated variable command value, the yaw angular acceleration estimating unit 102 estimates the yaw angular acceleration based on the manipulated variable. The estimation accuracy of the value dγhat can be improved.

  In the first embodiment, the F / B command unit 103 suppresses the control error σf calculated using the equation (4) to near zero by the feedback front wheel steering angle operation amount δfFB, and the control calculated using the equation (6). The error σu is suppressed by the feedback rear wheel left / right driving force difference operation amount uFB.

  That is, the steady deviation of the yaw rate is compensated by the front wheel steering angle δf, and the yaw rate deviation excluding the steady state is compensated for by the rear wheel left and right driving force difference, so that a steady yaw rate is generated at low energy at the front wheel steering angle δf, and the response The delay in yaw rate deviation compensation due to the slow front wheel steering angle δf can be compensated for by the rear wheel left / right driving force difference with a fast response.

  However, the F / B command unit 103 is not limited to this configuration, and if the yaw rate control using the yaw angular acceleration estimation value is used, the effect of improving the estimation accuracy of the yaw angular acceleration described later can be obtained.

[Response improvement for driving operation]
In the first embodiment, in the F / F command unit 101, based on the feedforward front wheel steering angle δfFF and the feedforward rear wheel driving force difference uFF calculated using the equations (2) and (3), the front wheel steering angle δf and Correct the rear wheel drive force difference. Accordingly, the follow-up delay of the yaw rate with respect to the target yaw rate tγ can be suppressed only by the feedback control of the F / B command unit 103 that follows the difference between the target yaw rate tγ and the yaw rate, and the response to the driving operation can be improved.

[simulation result]
The effect of the first embodiment over the prior art will be described using the computer simulation result of FIG.

  A case where the yaw angular acceleration is estimated using a conventional technique (a method described in Japanese Patent Laid-Open No. 2002-331951 in which yaw angular acceleration is estimated based on a time-dependent difference of a yaw rate detection value using a yaw rate sensor) is indicated by a broken line. The case where the yaw angular acceleration is estimated using the method of the first embodiment is indicated by a solid line, and the target response (normative response) of the yaw rate is indicated by a one-dot chain line.

  In FIG. 11, the upper stage (a) shows the time history of the yaw rate, and the lower stage (b) shows the time history of the yaw angular acceleration. From FIG. 11, in the prior art, the deviation of the yaw rate with respect to the target yaw rate is large due to the influence of the estimation delay of the yaw angular acceleration, and the yaw angular acceleration also vibrates. On the other hand, in Example 1, the estimation delay of the yaw angular acceleration is suppressed, the yaw rate follows the target yaw rate with high accuracy, and the norm response is realized smoothly and accurately without vibration of the yaw angular acceleration. .

[Application to rear center of gravity vehicles]
By setting the center of gravity of the vehicle closer to the rear, the stability limit speed, which is the speed at which the vehicle behavior becomes unstable, is set to a speed lower than the maximum speed of the vehicle, and the high gain near this unstable vehicle speed range is used. Some vehicles have improved turning performance. In this case, it is necessary to stabilize the vehicle behavior by control during normal traveling or straight traveling. However, in the technique described in Japanese Patent Laid-Open No. 6-64554, two lateral acceleration sensors are used for estimating the yaw angular acceleration. In addition, since the actual yaw rate is not detected, the yaw rate cannot be reliably stabilized, and a desired vehicle behavior may not be obtained.

  Since the actual yaw rate is detected using the yaw rate sensor 8 in the first embodiment, the yaw rate can be ensured even when the yaw motion performance is improved by using a vehicle with strong oversteer characteristics such as rear center of gravity. So that the desired vehicle behavior can be obtained.

Next, the effect will be described.
The vehicle motion control apparatus according to the first embodiment has the following effects.

  (1) In a vehicle motion control method for controlling a yaw rate of a vehicle based on a yaw rate operation amount (front wheel steering angle, rear wheel left / right driving force difference), a step (yaw rate sensor 8) for detecting a yaw rate γ, and yaw angular acceleration estimation Based on the value dγhat, the step (integrator 102j) for estimating the yaw rate γhat, the yaw rate manipulated variable, the yaw rate deviation (γ−γhat) that is the deviation between the yaw rate detected value γ and the yaw rate estimated value γhat, and the yaw rate deviation The yaw angular acceleration dγhat is estimated based on the yaw angular acceleration dγhat, and the yaw rate target is calculated based on the target yaw rate tγ, the yaw rate detection value γ, and the yaw angular acceleration estimated value dγhat. Step to calculate the yaw rate manipulated variable that satisfies the response (feedback front wheel steering angle manipulated variable δfFB, feedback rear wheel left / right driving force difference manipulated variable uFB) (F / B command) Part 103). As a result, it is possible to improve the control accuracy of the yaw rate without increasing costs and feeling uncomfortable with driving.

  (2) In a vehicle motion control device that controls the yaw rate of a vehicle based on the yaw rate manipulated variable (front wheel steering angle, rear wheel left / right driving force difference), the yaw rate sensor 8 that detects the yaw rate γ and the yaw angular acceleration estimated value dγhat Based on the integrator 102j for estimating the yaw rate γhat, the yaw rate manipulated variable, the yaw rate deviation (γ-γhat) that is the deviation between the yaw rate detected value γ and the yaw rate estimated value γhat, and the integrated value of this yaw rate deviation, Based on the yaw angular acceleration estimation unit 102 that estimates the yaw angular acceleration dγhat, and the yaw rate manipulated variable (feedback front wheel) that satisfies the target response of the yaw rate based on the target yaw rate tγ, the yaw rate detected value γ, and the yaw angular acceleration estimated value dγhat. And an F / B command unit 103 that calculates a steering angle operation amount ΔfFB and a feedback rear wheel left / right driving force difference operation amount uFB). As a result, it is possible to improve the control accuracy of the yaw rate without increasing costs and feeling uncomfortable with driving.

  (3) The yaw angular acceleration estimator 102 is a tire lateral force yaw moment calculator that estimates the yaw moment manipulated variable (MY, 2Ltuy *) based on the yaw rate manipulated variable (front wheel steering command δf, rear wheel drive force difference command uy *). 102a, the estimated yaw moment manipulated variable (MY, 2Ltuy *), the yaw rate deviation (γ-γhat), and the integrated value (γ-γhat) / s of this yaw rate deviation are each given a predetermined coefficient (1 / An adder 102i that adds values h1 (γ-γhat) and h2 (γ-γhat) multiplied by Iz, h1, h2) to calculate a yaw angular acceleration estimated value dγhat. That is, in order to correct the estimated deviation of the base value dγhat0 of the yaw angular acceleration with respect to the actual yaw angular acceleration dγ by the correction value dγhatm (equation (12)) corresponding to the proportional / integral compensation of the yaw rate deviation (γ-γhat), An estimated delay in yaw angular acceleration with respect to an operation input can be suppressed.

  (4) A vehicle body slip angle sensor 29 that detects the vehicle body slip angle β is provided, the yaw rate operation amount is the front wheel rudder angle, and the tire lateral force yaw moment calculation unit 102a includes the vehicle body slip angle β, the yaw rate detection value γ, and the vehicle speed. Based on V and the front wheel steering angle δf, the yaw moment MY due to the tire lateral force is estimated. Thereby, the estimation accuracy of the yaw moment MY can be further increased.

  (5) A wheel load estimating means (step S102) for estimating the wheel load of each wheel is provided, and the tire lateral force yaw moment calculating unit 102a calculates the tire lateral force based on each wheel load estimated value Zfl, Zfr, Zrl, Zrr. Estimate yaw moment MY by force. Thereby, the estimation accuracy of the yaw moment MY can be further increased.

  (6) The yaw angular acceleration estimation unit 102 calculates the coefficients h1 and h2 by which the yaw rate deviation (γ-γhat) and the integrated value (γ-γhat) / s of the yaw rate deviation are multiplied, as the yaw rate target response speed increases. Set to a large value. This suppresses the estimated delay of yaw angular acceleration when the yaw rate change is fast and the yaw angular acceleration increases, and suppresses the influence of noise when the yaw rate change is slow and the yaw angular acceleration becomes small, so Can be achieved.

  (7) Since the yaw rate manipulated variable is the left / right driving force difference uy * between the rear wheels 2RL and 2RR, the stability margin is increased compared to the case where the front and rear wheels are steered, and the vehicle can be stabilized more reliably. .

  (8) The F / B command unit 103 controls the control error based on the deviation of the yaw angular acceleration estimated value dγhat with respect to the yaw angular acceleration dγ according to the integrated value (γ−γhat) / s of the yaw rate deviation and the detected yaw rate value γ. A control error calculation unit 200 that calculates σf and a front wheel steering angle F / B operation amount calculation unit 201 that calculates a feedback front wheel steering angle operation amount ΔfFB proportional to the calculated control error σf are provided. Thereby, the steady deviation of the yaw rate can be compensated, and the yaw rate can be made to follow the target yaw rate tγ by the normative response.

  (9) Since the feedback front wheel rudder angle operation amount ΔfFB is the front wheel rudder angle Δf, the steady deviation of the yaw rate can be compensated with low energy by the front wheel rudder angle Δf.

  (10) The F / B command unit 103 includes a control error calculation unit 300 that calculates the control error σu based on the deviation of the yaw angular acceleration estimated value dγhat with respect to the yaw angular acceleration dγ according to the yaw rate deviation (γ-γhat), A driving force difference F / B operation amount calculation unit 301 that calculates a feedback rear wheel left / right driving force difference operation amount uFB proportional to the calculated control error σu. Thereby, the transient deviation of the yaw rate can be compensated, and the yaw rate can be made to follow the target yaw rate tγ by the normative response.

  (11) Since the feedback rear wheel left / right driving force difference manipulated variable uFB is the rear wheel left / right driving difference, the yaw rate deviation compensation delay due to the slow response front wheel steering angle δf It is possible to compensate, and it is possible to suppress the uncomfortable feeling of driving by improving the control accuracy.

  (12) The F / B command unit 103 sets the switching gain Kf that determines the feedback front wheel steering angle operation amount δfFB to the maximum value of the front wheel steering angle δf, and the switching gain Ku that determines the feedback rear wheel left and right driving force difference operation amount uFB The maximum value of wheel drive force difference. That is, by limiting δfFB, uFB based on the mechanical limit value, it is possible to realize the actual operation amount without saturating the operation amount command value, and the yaw angular acceleration estimation unit 102 determines the yaw rate operation amount. The estimation accuracy of the yaw angular acceleration based on it can be improved.

  (13) Inverse model of transfer function Qf (s, V) from front wheel rudder angle δf to yaw rate and transfer function Qu (s, V) from rear wheel left / right driving force difference to yaw rate, and from target yaw rate tγ to yaw rate Based on the transfer function D (s, V) indicating the normative response, the feedforward manipulated variable (feedforward front wheel steering angle δfFF, feedforward rear wheel driving force difference uFF) is calculated from the target yaw rate tγ and the vehicle speed V, An F / F command unit 101 that corrects the front wheel steering angle δf and the rear wheel driving force difference by the feedforward operation amount is provided. Thus, only by feedback control for following the difference between the target yaw rate tγ and the yaw rate, it is possible to suppress the follow-up delay of the yaw rate with respect to the target yaw rate tγ, and to improve the response to the driving operation.

  (14) The F / B command unit 103 matches the yaw angular acceleration according to the target yaw rate tγ and the detected yaw rate value γ with the yaw angular acceleration based on the norm response D (s, V) using the target yaw rate tγ as an input. . As a result, the yaw rate accurately follows the target yaw rate tγ with a normative response, and a smooth turning behavior can be provided to the driver.

(Other examples)
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Any change in the design of the range is included in the present invention.

  For example, in the first embodiment, the front wheel steering angle and the rear wheel left / right driving force difference are used as the yaw rate operation amount, but the present invention is not limited to this combination, and the front wheel steering angle, rear wheel steering angle, and rear wheel are not limited to this combination. It is also possible to use one or more operation amounts that can control the yaw rate, such as a left / right driving force difference and a front wheel left / right driving force difference. Further, the control amount of the operation amount input to the yaw angular acceleration estimation unit is improved with respect to the prior art in any one of the front wheel steering angle and the rear wheel left / right driving force difference.

  Further, in the first embodiment, an example in which the vehicle body side slip angle is detected by the vehicle body side slip angle sensor is shown. However, as in the technique described in Japanese Patent Laid-Open No. 5-185942, the lateral acceleration and yaw rate at two locations of the vehicle are shown. From this, it may be estimated using an observer based on a mathematical model of vehicle motion characteristics.

It is a block diagram of the electric vehicle to which the vehicle motion control apparatus of Example 1 is applied. 4 is a flowchart illustrating a flow of a vehicle motion control process calculated by an integrated controller 30 according to the first embodiment. FIG. 3 is a block diagram of yaw rate servo control calculation in the first embodiment. 2 is a target driving force map according to the first embodiment. 2 is a target lateral force map according to the first embodiment. It is a feedback front wheel steering angle operation amount calculation block diagram of the first embodiment. FIG. 6 is a feedback rear wheel left / right driving force difference operation amount calculation block diagram of the first embodiment. FIG. 2 is a block diagram of yaw angular acceleration estimation according to the first embodiment. It is a tire lateral force characteristic map with respect to a tire side slip angle absolute value. 3 is an estimated gain setting map for a target yaw rate change rate according to the first embodiment. 3 is a computer simulation result showing the effect of Example 1.

Explanation of symbols

2FL, 2FR Front wheel 2RL, 2RR Rear wheel 3RL, 3RR Electric motor
4RL, 4RR Reducer 5RL, 5RR Drive circuit 6 Lithium ion battery 8 Yaw rate sensor 11 Steering wheel 12 Auxiliary steering motor 13 Control circuit 14 Steering gear 21 Steering angle sensor 23 Accelerator pedal sensor 25, 26 Rotation sensor 28 Acceleration sensor 29 Car body side slip Angle sensor 30 integrated controller
100 Target value calculator
101 F / F command section
102 Yaw angular acceleration estimator
102a Tire lateral force yaw moment calculator
102b multiplier
102c adder
102d multiplier
102e comparator
102f multiplier
102g multiplier
102h integrator
102i adder
102j integrator
103 F / B command section
104 vehicles
200 Control error calculator
201 Front wheel rudder angle F / B manipulated variable calculator
300 Control error calculator
301 Driving force difference F / B manipulated variable calculator

Claims (14)

In a vehicle motion control method for performing yaw rate control of a vehicle based on a yaw rate operation amount,
Detecting the yaw rate;
Estimating a yaw rate based on a yaw angular acceleration estimate;
Estimating the yaw angular acceleration based on the yaw rate manipulated variable, a yaw rate deviation that is a deviation between the yaw rate detection value and the yaw rate estimation value, and an integrated value of the yaw rate deviation;
Calculating a yaw rate manipulated variable that satisfies the target response of the yaw rate based on the target yaw rate, the yaw rate detection value, and the yaw angular acceleration estimated value;
A vehicle motion control method comprising: In a vehicle motion control device that performs yaw rate control of a vehicle based on a yaw rate operation amount,
A yaw rate detection means for detecting the yaw rate;
Yaw rate estimating means for estimating the yaw rate based on the yaw angular acceleration estimated value;
A yaw angular acceleration estimating means for estimating the yaw angular acceleration based on the yaw rate manipulated variable, a yaw rate deviation that is a deviation between the yaw rate detected value and the yaw rate estimated value, and an integral value of the yaw rate deviation;
Feedback manipulated variable calculation means for calculating a yaw rate manipulated variable that satisfies the target response of the yaw rate based on the target yaw rate, the yaw rate detection value, and the yaw angular acceleration estimated value;
A vehicle motion control device comprising: The vehicle motion control device according to claim 2,
The yaw angular acceleration estimation means includes a yaw moment manipulated variable estimator for estimating a yaw moment manipulated variable based on the yaw rate manipulated variable,
A yaw angular acceleration calculator that calculates a yaw angular acceleration estimated value by adding a value obtained by multiplying each of the estimated yaw moment manipulated variable, the yaw rate deviation, and the integrated value of the yaw rate deviation by a predetermined coefficient;
A vehicle motion control device comprising: In the vehicle motion control device according to claim 3,
A vehicle side slip angle detecting means for detecting or estimating a vehicle side slip angle is provided.
The yaw rate operation amount is a steering angle of a steered wheel,
The yaw moment operation amount estimation unit estimates the yaw moment operation amount based on the vehicle body side slip angle, the yaw rate detection value, the vehicle speed, and the steered wheel steering angle. The vehicle motion control device according to claim 4,
A wheel load estimating means for estimating the wheel load of each wheel;
The yaw moment operation amount estimation unit estimates the yaw moment operation amount based on each wheel load estimation value. The vehicle motion control device according to any one of claims 3 to 5,
The yaw angular acceleration estimation means sets each coefficient to be multiplied by the yaw rate deviation and an integral value of the yaw rate deviation to a larger value as the target response speed of the yaw rate is higher. The vehicle motion control device according to any one of claims 2 to 6,
The vehicle motion control device according to claim 1, wherein the yaw rate operation amount is a difference between right and left driving forces of driving wheels. The vehicle motion control device according to any one of claims 2 to 7,
The feedback manipulated variable calculation means includes
A first control error calculation unit that calculates a first control error based on a deviation of a yaw angular acceleration estimated value with respect to a yaw angular acceleration according to the integral value of the yaw rate deviation and the yaw rate detection value;
A first yaw rate manipulated variable calculator for calculating a first yaw rate manipulated variable proportional to the calculated first control error;
A vehicle motion control device comprising: The vehicle motion control device according to claim 8,
The vehicle motion control device according to claim 1, wherein the first yaw rate operation amount is a steering angle of a steered wheel. The vehicle motion control device according to any one of claims 2 to 9,
The feedback manipulated variable calculation means includes
A second control error calculation unit that calculates a second control error based on a deviation of the yaw angular acceleration estimated value from the yaw angular acceleration according to the yaw rate deviation;
A second yaw rate manipulated variable calculator for calculating a second yaw rate manipulated variable proportional to the calculated second control error;
A vehicle motion control device comprising: The vehicle motion control device according to claim 10,
The vehicle motion control device according to claim 2, wherein the second yaw rate operation amount is a difference between right and left driving forces of driving wheels. The vehicle motion control device according to any one of claims 2 to 11,
The vehicle motion control apparatus according to claim 1, wherein the feedback operation amount calculation means limits the yaw rate operation amount based on a mechanical limit value. The vehicle motion control device according to any one of claims 2 to 12,
Based on the inverse model of the response model from the yaw rate manipulated variable to the yaw rate and the normative response from the target yaw rate to the yaw rate, the feedforward manipulated variable is calculated from the target yaw rate and the vehicle speed, and the yaw rate is calculated based on the feedforward manipulated variable. A vehicle motion control apparatus comprising a feedforward manipulated variable calculating means for correcting an manipulated variable. The vehicle motion control device according to claim 13,
The feedback manipulated variable calculation means matches the yaw angular acceleration according to the target yaw rate and the detected yaw rate with the yaw angular acceleration by the normative response using the target yaw rate as an input. apparatus.

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