JP4692499B2 - Vehicle vibration suppression control device - Google Patents

Description

  The present invention relates to a vibration damping control device for a vehicle such as an automobile, and more particularly to a vibration damping control device that controls a vehicle driving output (driving force or driving torque) to suppress vibration of a vehicle body.

  Vibrations such as pitch and bounce while the vehicle is running are generated by braking / driving force (or inertial force) that acts on the vehicle body during acceleration / deceleration of the vehicle or other external force that acts on the vehicle body. At the time of driving, this is reflected in “wheel torque” (torque acting between the wheel and the grounded road surface) acting on the road surface. Therefore, in the field of vehicle vibration suppression control, it has been proposed to suppress the vibration of the vehicle body while the vehicle is running by adjusting the wheel torque through the drive output control of the vehicle engine or other drive device. (For example, see Patent Documents 1 and 2). In such vibration suppression control by drive output control, there is a request for acceleration / deceleration of the vehicle using a motion model constructed assuming a dynamic model of so-called unsprung and unsprung vibrations of the vehicle body. Or, when an external force (disturbance) acts on the vehicle body and the wheel torque fluctuates, the pitch bounce vibration generated in the vehicle body is predicted, and the drive output of the vehicle drive device is controlled so that the predicted vibration is suppressed. Adjusted. In the case of this type of vibration suppression control, the generation of vibration energy is suppressed by adjusting the source of the force that generates vibration, rather than by absorbing vibration energy generated as in the case of vibration suppression control by the suspension. Therefore, the vibration damping action is relatively quick and the energy efficiency is good. Further, in the vibration damping control based on the drive output control, since the control target is concentrated on the drive output (drive torque) of the drive device, the control adjustment is relatively easy.

  In the vibration damping control device (or driving force control device) that performs the vibration damping control by the drive output control as described above, the wheel torque actually generated in the wheel is already in the control as described above. Feedback is fed back to the vibration suppression control device as a disturbance, and an adjustment amount of the drive output necessary for vibration suppression due to the disturbance is determined based on wheel torque actually generated in the vehicle. However, sensors that can directly detect the value of the wheel torque while the vehicle is running, such as a wheel torque sensor and a wheel six-component force meter, exclude the test vehicle, etc. due to vehicle design or cost issues. It is not mounted on a normal vehicle. Therefore, in the vibration damping control device as described above, the wheel torque value fed back as a disturbance input is based on other easily detectable parameters such as the wheel speed and the rotational speed of the output shaft of the vehicle drive device. The estimated wheel torque value is used (for example, see Japanese Patent Application No. 2006-284642 by the applicant of the present application).

When the actual wheel torque value input as disturbance of the vibration suppression control as described above is estimated using the wheel speed or the rotational speed of the output shaft of the vehicle drive device, the wheel force acting on the road surface is If the grip limit (maximum friction circle) is exceeded, the wheel will “slip” on the road surface (“slip state”), and the accuracy of the estimated wheel torque will deteriorate. Therefore, in the above-mentioned Japanese Patent Application No. 2006-284642, when estimating the wheel torque, the wheel slip state amount indicating the slip state of the wheel is calculated, and the larger the degree of slip represented by the wheel slip state amount, the larger the wheel torque estimated value. It is proposed to correct the estimated wheel torque value so that the absolute value of becomes smaller. Here, the “degree of slip” may be considered to correspond to the magnitude of the frictional force between the wheel and the road surface when the wheel is in a slip state (the surface of the wheel and the road surface). When relative slip occurs between the wheels, the slip between the wheel surface and the road surface increases as the frictional force decreases.) Further, the “wheel slip state amount” is an index that can detect that the wheel transitions from the grip state to the slip state. As the “wheel slip state amount”, for example, the wheel slip rate or the slip ratio (these In the terminology, the term “slip” is used. In this case, “slip” refers to the vehicle speed and wheel speed (whether the tire is gripping the road surface or not). (The value multiplied by the radius), which is different from “slip” in the sense that the wheel “slides” on the road surface as in the case of the above “slip state”) or vehicle Ratio of the wheel speed of the driving wheel to the wheel speed of the driven wheel of the vehicle (during vehicle acceleration, the wheel speed of the driven wheel is a value corresponding to the vehicle speed regardless of whether the driving wheel is in the grip state or not. However, the wheel speed of the drive wheel is When becomes-up state, not correspond to the vehicle speed.) It is employed.
JP 2004-168148 A JP 2006-69472 A

By the way, in recent vehicles such as automobiles, a control device for controlling a braking system device of the vehicle, for example, VSC (Vehicle Stability Control), TRC (Traction Control), VDIM (registered trademark) (Vehicle Dynamics Integrated Management System). ), A control device such as ABS (hereinafter referred to as “braking control device”). In these braking control devices, the “wheel slip state amount” indicating the slip state of the wheel as described above is calculated, and based on the calculated value, the control method such as control for reducing the slip ratio of the wheel is applied to each control method. Executes the corresponding control. Therefore, in the embodiment of Japanese Patent Application No. 2006-284642, when the vibration damping control device that performs the vibration damping control by the drive output control as described above is mounted on a vehicle on which the braking control device as described above is mounted. Is also configured to use the “wheel slip state amount” calculated by the vehicle braking control device, thereby simplifying or improving the control configuration in one vehicle. (Avoid measuring or calculating the same measurement value, control amount, etc. redundantly).

  As described above, when the damping control device is configured to use the “wheel slip state amount” calculated by the braking control device, the damping control device is operated in a situation where the braking control device is not operating for any reason. Information on the degree of wheel slip is not input to the vibration control device, and in this case, vibration suppression control based on the estimated wheel torque value may not be performed satisfactorily. However, in Japanese Patent Application No. 2006-284642, no countermeasure is taken in such a situation.

  Thus, one main object of the present invention is to receive information on the state of wheel slip from the braking control device as described above, and in the vibration damping control device based on the drive output control based on the information, the braking control device It is to propose a control mode in the case where is in a non-operating state.

  According to the present invention, there is provided a vibration suppression control device that executes vibration suppression control for suppressing vehicle body pitch or bounce vibration by vehicle drive output control, and is generated at a ground contact point between a vehicle wheel and a road surface. A wheel torque estimated value acquisition unit that acquires a wheel torque estimated value that acts on the wheel that performs, a drive torque control unit that controls the drive torque of the vehicle to suppress the pitch or bounce vibration amplitude based on the wheel torque estimated value, and A slip state amount acquisition unit that acquires a wheel slip state amount indicating a wheel slip state from a vehicle braking control device for reducing wheel slip, and is driven based on the degree of slip represented by the wheel slip state amount When the braking control device is not in an operable state, the damping control device for correcting the torque control amount is compared with when the braking control device is in an operable state. Damping control system for a vehicle, characterized in that to reduce the control amount of the driving torque is provided.

  As described above, in the case of the vibration damping control device adapted to acquire the wheel slip state quantity indicating the slip state of the wheel from the vehicle braking control device, the braking control device is not in an operable state or When the operation is prohibited, information on whether the wheel is in the grip state or the slip state is not obtained, and therefore, the control amount of the drive torque may not be appropriately controlled. For example, when the wheel is in a slip state, the estimated wheel torque value based on the wheel speed is larger than the torque actually generated on the wheel, and such wheel torque estimation is performed. The control amount of the drive torque calculated based on the value not only reduces the vibration damping effect, but can also cause vibrations in the longitudinal direction in the vehicle due to excessive drive torque fluctuation. . Such a situation is contrary to the purpose of improving the steering stability and riding comfort of the vehicle, which is expected for vibration suppression control. Therefore, when the brake control device is not in an operable state, the control amount of the drive torque is reduced compared to when the brake control device is in an operable state. Problems caused by the operation will be solved.

  In the above-described vibration damping control device of the present invention, in particular, the control amount of the drive torque by the drive torque control unit is based on the wheel torque estimation value and the drive request amount by the vehicle driver (for example, by depressing the accelerator pedal). If the braking control device is not in an operable state, the control amount of the driving force based on the estimated wheel torque value may be substantially reduced to zero. As a result, when the state of the wheel cannot be detected and the estimated wheel torque cannot be calculated accurately, the vibration suppression control itself for the disturbance is substantially stopped, and the vibration control device is activated. Occurrence is suppressed. On the other hand, with respect to vibration suppression control (corresponding to “feedforward control” in the following embodiment) based on the drive demand amount by the driver of the vehicle, the control amount depends on the accuracy of the estimated wheel torque. So it may be executed. However, when the wheel tire is in a slip state, the drive torque control for the wheel is not executed well, so the control amount may be reduced or the control execution may be stopped.

In the above configuration, the braking control device may be at least one selected from the group consisting of ABS control, VSC, and TRC that are selectively operable by a vehicle driver, When the brake control device is not activated by the driver's selection, the control amount of the drive torque may be reduced as compared to when the brake control device is operable. In addition, the vehicle is equipped with a device for comprehensively controlling the behavioral stability of the vehicle, including so-called “VDIM” (registered trademark) [hereinafter the same] , that is, control such as ABS control, VSC, TRC, or steering control. In some cases, the braking control device may be part of the VDIM, and may reduce the amount of control of the drive torque when the VDIM is not activated by the driver's selection. In these cases, when the control amount of the drive torque is reduced, the vibration suppression control based on the estimated wheel torque value may be substantially stopped.

  Further, when the braking control device is not in an operable state due to an abnormality in the vehicle braking device, the state of the wheel cannot be detected, and in this case, the braking control device is in an operable state. The control amount of the driving torque may be reduced as compared with the case. Also in this case, when the control amount of the drive torque is reduced, the vibration suppression control based on the estimated wheel torque value may be substantially stopped.

  According to the configuration of the present invention described above, the vibration damping control device uses the wheel slip state amount calculated by the braking control device in order to simplify or increase the efficiency of the control mounted on one vehicle. In the case where the brake control device is configured, it is possible to avoid the occurrence of a malfunction due to the operation of the vibration suppression control device in a situation where the brake control device is not operable. In particular, in recent years, in vehicles, it is possible to execute vehicle control in an integrated manner, for example, VDIM so that a plurality of controls can be executed. In order to reduce the burden on the vehicle, it is necessary to simplify and improve the configuration. The configuration of the present invention avoids the occurrence of an unexpected and inappropriate action of the vibration suppression control device when a plurality of control configurations are mounted in such a single vehicle. It can be said that there is.

  Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention.

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings. In the figure, the same reference numerals indicate the same parts.

Configuration of Device FIG. 1 (A) a vehicle such as an automobile in which the preferred embodiment of the vibration damping control device is mounted of the present invention is schematically shown. In the figure, the vehicle 10 having the left and right front wheels 12FL and 12FR and the left and right rear wheels 12RL and 12RR is driven in the normal manner according to the depression of the accelerator pedal 14 by the driver. A drive device 20 that generates torque is mounted. In the illustrated example, the driving device 20 is configured such that driving torque or rotational driving force is transmitted from the engine 22 to the rear wheels 12RL and 12RR via the torque converter 24, the automatic transmission 26, the differential gear device 28, and the like. Composed. However, an electric type in which an electric motor is used instead of the engine 22 or a hybrid type driving device having both an engine and an electric motor may be used. The vehicle may be a four-wheel drive vehicle or a front wheel drive vehicle. Although not shown for the sake of simplicity, the vehicle 10 is provided with a braking device that generates a braking force on each wheel and a steering device for controlling the steering angle of the front wheels or the front and rear wheels, as in a normal vehicle. .

  The operation of the driving device 20 is controlled by the electronic control device 50. The electronic control unit 50 may include a microcomputer having a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other by a bidirectional common bus, and a driving circuit. The electronic control device 50 includes a signal representing a wheel speed Vwi (i = FL, FR, RL, RR) from a wheel speed sensor 30i (i = FL, FR, RL, RR) mounted on each wheel, a vehicle Signals such as the engine rotational speed ne, the transmission rotational speed no, and the accelerator pedal depression amount θa are input from sensors provided in the respective sections. In addition to the above, it should be understood that various detection signals for obtaining various parameters necessary for various controls to be executed in the vehicle of the present embodiment may be input. As schematically shown in more detail in FIG. 1B, the electronic control unit 50 operates the drive control unit 50a for controlling the operation of the drive unit 20 and the operation of the braking unit (not shown). You may comprise from the braking control apparatus 50b to control.

  The braking control device 50b has a braking control such as ABS control, VSC, and TRC known to those skilled in the art, that is, frictional force between the wheel and the road surface (vector sum of the longitudinal force and lateral force of the wheel) becomes excessive. Controlling the longitudinal force on the wheel or the slip ratio to prevent the deterioration of the behavior of the vehicle due to the frictional force of the wheel exceeding the limit or preventing the wheel from exceeding the limit. Alternatively, it may be a VDIM that improves the behavior of the vehicle by including steering control in addition to ABS control, VSC, and TRC wheel slip rate control. In addition, when VDIM is mounted, a braking control apparatus will comprise a part of VDIM. As shown in the figure, the braking control device receives a pulse-type electrical signal that is sequentially generated every time the wheel rotates by a predetermined amount from the wheel speed sensors 30FR, FL, RR, RL of each wheel, The rotational speed of the wheel is calculated by measuring the time interval at which such sequentially input pulse signals arrive, and the wheel speed value r · ω is calculated by multiplying this by the wheel radius. Further, as will be described in detail later, in the calculation of the estimated wheel torque value, whether or not the wheel tire is in a slip state, and when it is in a slip state, an index indicating the degree of the slip is “wheel slip. A “state quantity” is calculated. The wheel speed value r · ω and the wheel slip state quantity are transmitted to the drive control device 50a in order to calculate a wheel torque estimated value. The calculation from the wheel rotation speed to the wheel speed may be performed by the drive control device 50a. In this case, the wheel rotation speed is given from the braking control device 50b to the drive control device 50a.

  As described above, braking control such as ABS control, VSC, TRC, etc., or control by VDIM is an ON-provided location where the driver of the vehicle can access (for example, any location on the front panel of the driver's seat). An OFF switch 52 (in the figure, only one is provided for the sake of simplicity, but it may be provided for each control that can be executed) is selectively activated. That is, these braking controls are operable only when the switch 52 is ON, and are disabled when the switch 52 is OFF, according to the driver's will. Although not shown, when there is an abnormality in the operation of the braking device or when there is an abnormality in the wheel speed sensor, it is detected by those skilled in the art that braking control is impossible in a known manner. In that case, the operation of the braking control devices listed above is prohibited. Then, when the braking control device is in the operation prohibited state, the calculation of the wheel slip state amount is not executed. Therefore, in this case, as described below, the vibration suppression control based on the estimated wheel torque value in the vibration suppression control device is stopped. For this purpose, various controls for controlling the slip ratio of the wheels such as VSC, ABS or TRC can be executed from the braking control device 50b to the drive control device 50a in addition to the wheel speed value and the wheel slip state quantity. A signal indicating whether or not it is in a state is transmitted.

  Further, the correction of the estimated wheel torque value depending on the degree of the slip state of the wheel may be performed only when the control such as VSC, ABS, or TRC is actually executed as described below. Therefore, in addition to the series of signals described above, information indicating whether or not various controls for controlling the slip ratio of the wheels such as VSC, ABS, or TRC are performed is transmitted from the braking control device 50b to the drive control device 50a. . Further, when there is an abnormality in the wheel speed sensor and the wheel speed value cannot be acquired, it is necessary to change the estimation method of the wheel torque estimated value, so the wheel speed invalid state information indicating that the wheel speed value cannot be acquired. May be provided from the braking control device 50b to the drive control device 50a.

  In the drive control device 50a, the target output torque (required drive torque) of the drive device requested by the driver based on the accelerator pedal depression amount θa is determined based on the drive request from the driver. However, in the drive control device of the present invention, the required drive torque is corrected to execute the pitch / bounce vibration damping control of the vehicle body by the drive torque control, and a control command corresponding to the corrected request torque is issued. It is given to the drive device 20. In this pitch / bounce vibration damping control, (1) calculation of the estimated wheel torque of the driving wheel by the force acting between the driving wheel and the road surface, and (2) pitch based on the vehicle vibration model. / Calculation of bounce vibration state quantity, (3) Calculation of correction amount of wheel torque for suppressing pitch / bounce vibration state quantity, and correction of required torque based on this. The estimated wheel torque value of (1) may be calculated based on the wheel speed value of the drive wheel (or the wheel rotation speed of the drive wheel) received from the braking control device 50b or the engine rotation speed ne. It should be understood that the vibration damping control device of the present invention is realized in the processing operations (1) to (3).

FIG. 2 (A) shows an example of a driving force control system that performs pitch / bounce vibration damping control of a vehicle body, when the driving device is activated based on the driving request of the driver and the wheel torque fluctuates. In the vehicle body 10 as described above, bounce vibration in the vertical direction (z direction) of the center of gravity Cg of the vehicle body and pitch vibration in the pitch direction (θ direction) around the center of gravity of the vehicle body can occur. Further, when an external force or torque (disturbance) acts on the wheels from the road surface while the vehicle is running, the disturbance is transmitted to the vehicle, and vibrations in the bounce direction and the pitch direction may also occur in the vehicle body. Therefore, in the illustrated embodiment, a motion model of the pitch / bounce vibration of the vehicle body is constructed, and in that model, the required drive torque (value converted into wheel torque) and the current wheel torque (estimated). ) And the rate of change dz / dt, dθ / dt, that is, the state variable of the body vibration is calculated, and the state variable obtained from the model converges to zero. That is, the drive torque of the drive device is adjusted so that the pitch / bounce vibration is suppressed (the required drive torque is corrected).

  FIG. 2B schematically shows the configuration of the driving force control in the embodiment of the present invention in the form of a control block (note that the operation of each control block (except for C0 and C3) It is executed by either the drive control device 50a or the braking control device 50b of the electronic control device 50). Referring to FIG. 2 (B), in the drive torque control according to the embodiment of the present invention, generally speaking, a drive controller for giving a drive request of the driver to the vehicle, and suppressing the pitch / bounce vibration of the vehicle body. And a vibration suppression controller for correcting the driving request of the driver. In the drive controller, after the driver's drive request, that is, the accelerator pedal depression amount (C0) is converted into the required drive torque in a normal manner (C1), the required drive torque is driven. It is converted into a control command for the device (C2) and transmitted to the drive device (C3). [The control command includes a target throttle opening for a gasoline engine, a target fuel injection amount for a diesel engine, a target current amount for a motor, and the like. ]

  On the other hand, the vibration damping controller includes a feedforward control part and a feedback control part. The feedforward control portion has a so-called optimum regulator configuration, and here, as described below, a value obtained by converting the required driving torque of C1 into wheel torque (driver required wheel torque Tw0) is the pitch of the vehicle body. The motion model portion (C4) of the bounce vibration is input, and in the motion model portion (C4), the response of the state variable of the vehicle body to the input torque is calculated, and the required driving wheel torque that converges the state variable to the minimum is calculated. A correction amount is calculated (C5). In the feedback control portion, the wheel torque estimator (C6) calculates a wheel torque estimated value Tw as will be described later, and the wheel torque estimated value is calculated based on the feedback control gain FB (in the driving model). After the driver requested wheel torque Tw0 and the gain for adjusting the balance of contribution between the wheel torque estimated value Tw) are multiplied, the disturbance input is added to the requested wheel torque and input to the motion model portion (C4). Thereby, the correction amount of the required wheel torque with respect to the disturbance is also calculated. The correction amount of the required wheel torque of C5 is converted into a unit of the required torque of the drive device and transmitted to the adder (C1a), and thus the required drive torque is corrected so that pitch bounce vibration does not occur. Thereafter, it is converted into a control command (C2) and given to the driving device (C3).

Principle of Vibration Suppression Control In the vibration suppression control in the embodiment of the present invention, as already mentioned, first, assuming the dynamic motion model in the bounce direction and the pitch direction of the vehicle body, the driver requested wheel A state equation of state variables in the bounce direction and the pitch direction is input with the torque Tw0 and the estimated wheel torque value Tw (disturbance) as inputs. Then, from this state equation, the input (torque value) for converging the bounce and pitch state variables to 0 is determined using the theory of the optimal regulator, and the required drive torque is corrected based on the obtained torque value. The

ここに於いて、Ｌｆ、Ｌｒは、それぞれ、重心から前輪軸及び後輪軸までの距離であり、ｒは、車輪半径であり、ｈは、重心の路面からの高さである。なお、式（１ａ）に於いて、第１、第２項は、前輪軸から、第３、４項は、後輪軸からの力の成分であり、式（１ｂ）に於いて、第１項は、前輪軸から、第２項は、後輪軸からの力のモーメント成分である。式（１ｂ）に於ける第３項は、駆動輪に於いて発生している車輪トルクＴ（＝Ｔｗ０＋Ｔｗ）が車体の重心周りに与える力のモーメント成分である。 As a dynamic motion model in the bounce direction and pitch direction of the vehicle body, for example, as shown in FIG. 3A, the vehicle body is regarded as a rigid body S of mass M and moment of inertia I, and the rigid body S has an elastic modulus kf. And a front wheel suspension with a damping rate cf, and a rear wheel suspension with an elastic modulus kr and a damping rate cr (car body sprung vibration model). In this case, the motion equation in the bounce direction and the motion equation in the pitch direction of the center of gravity of the vehicle body are expressed as the following Equation 1.

Here, Lf and Lr are distances from the center of gravity to the front wheel shaft and the rear wheel shaft, respectively, r is a wheel radius, and h is a height of the center of gravity from the road surface. In Equation (1a), the first and second terms are components of force from the front wheel shaft, and the third and fourth terms are components of force from the rear wheel shaft. In Equation (1b), the first term Is the moment component of the force from the front wheel shaft, and the second term is the force from the rear wheel shaft. The third term in the equation (1b) is a moment component of the force that the wheel torque T (= Tw0 + Tw) generated in the drive wheel gives around the center of gravity of the vehicle body.

であり、行列Ａの各要素a1-a4及びb1-b4は、それぞれ、式（１ａ）、（１ｂ）のｚ、θ、ｄｚ／ｄｔ、ｄθ／ｄｔの係数をまとめることにより与えられ、
a1=-(kf+kr)/M、a2=-(cf+cr)/M、
a3=-(kf・Lf-kr・Lr)/M、a4=-(cf・Lf-cr・Lr)/M、
b1=-(Lf・kf-Lr・kr)/I、b2=-(Lf・cf-Lr・cr)/I、
b3=-(Lf²・kf+Lr²・kr)/I、b4=-(Lf²・cf+Lr²・cr)/I
である。また、ｕ(t)は、
ｕ(t)＝Ｔ
であり、状態方程式（２ａ）にて表されるシステムの入力である。従って、式（１ｂ）より、行列Ｂの要素p1は、
p1=h/(I・r)
である。 The above formulas (1a) and (1b) are expressed as (linear) as shown in the following formula (2a) with the vehicle body displacements z and θ and their change rates dz / dt and dθ / dt as the state variable vector X (t). It can be rewritten in the form of a system state equation.
dX (t) / dt = A · X (t) + B · u (t) (2a)
Here, X (t), A, and B are respectively

And each element a1-a4 and b1-b4 of the matrix A is given by combining the coefficients of z, θ, dz / dt, dθ / dt in the equations (1a) and (1b), respectively.
a1 =-(kf + kr) / M, a2 =-(cf + cr) / M,
a3 =-(kf ・ Lf-kr ・ Lr) / M, a4 =-(cf ・ Lf-cr ・ Lr) / M,
b1 =-(Lf ・ kf-Lr ・ kr) / I, b2 =-(Lf ・ cf-Lr ・ cr) / I,
b3 =-(Lf ²・ kf + Lr ²・ kr) / I, b4 =-(Lf ²・ cf + Lr ²・ cr) / I
It is. U (t) is
u (t) = T
And is an input of the system represented by the state equation (2a). Therefore, from equation (1b), the element p1 of the matrix B is
p1 = h / (I ・ r)
It is.

In the equation of state (2a)
u (t) = − K · X (t) (2b)
Then, the equation of state (2a) is
dX (t) / dt = (A-BK) .X (t) (2c)
It becomes. Accordingly, the initial value X ₀ (t) of X (t) is set as X ₀ (t) = (0,0,0,0) (assuming that there is no vibration before torque is input). ), When the differential equation (2c) of the state variable vector X (t) is solved, the magnitude of X (t), that is, the displacement rate in the bounce direction and the pitch direction and its time change rate, is converged to zero. When the gain K is determined, the torque value u (t) for suppressing the pitch bounce vibration is determined.

The gain K can be determined by using a so-called optimal regulator theory. According to this theory, a quadratic evaluation function J = 1/2 · ∫ (X ^T QX + u ^T Ru) dt (3a)
(Integral range is 0 to ∞)
When the value of is the minimum, the matrix K that minimizes the evaluation function J by the stable convergence of X (t) in the state equation (2a) is
K = R ⁻¹・ B ^T・ P
It is known to be given by Where P is the Riccati equation
^{-dP / dt = A T P +} PA + Q-PBR -1 B T P
Is the solution. The Riccati equation can be solved by any method known in the field of linear systems, which determines the gain K.

などと置いて、式（３ａ）に於いて、状態ベクトルの成分うち、特定のもの、例えば、ｄｚ／ｄｔ、ｄθ／ｄｔ、のノルム（大きさ）をその他の成分、例えば、ｚ、θ、のノルムより大きく設定すると、ノルムを大きく設定された成分が相対的に、より安定的に収束されることとなる。また、Ｑの成分の値を大きくすると、過渡特性重視、即ち、状態ベクトルの値が速やかに安定値に収束し、Ｒの値を大きくすると、消費エネルギーが低減される。 Note that Q and R in the evaluation function J and Riccati equation are respectively a semi-positive definite symmetric matrix and a positive definite symmetric matrix, which are weight matrices of the evaluation function J determined by the system designer. For example, in the case of the motion model considered here, Q and R are

In Equation (3a), a specific one of the components of the state vector, for example, the norm (magnitude) of dz / dt, dθ / dt, and the other components, for example, z, θ, If the value is set to be larger than the norm, components having a larger norm are converged relatively stably. Further, when the value of the Q component is increased, the transient characteristics are emphasized, that is, the value of the state vector quickly converges to a stable value, and when the value of R is increased, the energy consumption is reduced.

  In the actual operation of the vibration suppression control device, as shown in the block diagram of FIG. 2B, in the motion model C4, the differential equation of Expression (2a) is solved using the torque input value. Thus, the state variable vector X (t) is calculated. Next, at C5, the value U () obtained by multiplying the state vector X (t), which is the output of the motion model C4, by the gain K determined to converge the state variable vector X (t) to 0 or the minimum value as described above. t) is subtracted from the required driving torque in the adder (C1a) (converted to the torque of the driving device) (for the calculation of the movement model C4, it is also fed back to the torque input value of the movement model C4). (State feedback). The system represented by equations (1a) and (1b) is a resonant system, and for any input, the value of the state variable vector is substantially the natural vibration of the system. Only frequency components in a band having a certain spectral characteristic centered on the number are obtained. Thus, by constructing such that U (t) (converted value) is subtracted from the required drive torque, a component of the natural frequency of the system, that is, pitch bounce vibration is generated in the vehicle body. The component is corrected, and the pitch bounce vibration in the vehicle body is suppressed. When a fluctuation that causes pitch bounce vibration occurs in Tw (disturbance) transmitted from the wheel torque estimator, a required torque command that is input to the drive device so that the vibration due to the Tw (disturbance) converges. Is modified using -U (t).

  The resonance frequency of vibration in the pitch bounce direction of a vehicle such as a normal automobile is approximately 1 to 2 Hz, and the speed of vibration in such a frequency band is a control response of wheel torque to a request command in the current vehicle. Is a level at which a torque disturbance in the wheel can be detected and a compensation amount for the disturbance can be reflected in the driving torque of the wheel. Therefore, the disturbance torque generated in the wheel that can cause pitch bounce vibration and the pitch bounce vibration caused by this are offset by the fluctuation of the drive torque output by the drive device by correcting the required drive torque by vibration suppression control. Become.

ここに於いて、xf、xrは、前輪、後輪のばね下変位量であり、mf、mrは、前輪、後輪のばね下の質量である。式（４ａ）−（４ｂ）は、ｚ、θ、xf、xrとその時間微分値を状態変数ベクトルとして、図３（Ａ）の場合と同様に、式（２ａ）の如き状態方程式を構成し（ただし、行列Ａは、８行８列、行列Ｂは、８行１列となる。）最適レギュレータの理論に従って、状態変数ベクトルの大きさが０を収束させるゲイン行列Ｋを決定することができる。実際の制振制御は、図３（Ａ）の場合と同様である。 As a dynamic motion model in the bounce direction and the pitch direction of the vehicle body, for example, as shown in FIG. 3B, in addition to the configuration of FIG. A model that takes into account the above (vehicle body sprung / lower vibration model) may be employed. Assuming that the tires for the front wheels and the rear wheels have the elastic moduli ktf and ktr, respectively, the equation of motion in the bounce direction and the equation of motion in the pitch direction of the center of gravity of the vehicle body are as understood from FIG. The following equation 4 is expressed.

Here, xf and xr are unsprung displacement amounts of the front and rear wheels, and mf and mr are unsprung masses of the front and rear wheels. Equations (4a)-(4b) form a state equation as shown in Equation (2a), similarly to the case of FIG. 3A, with z, θ, xf, xr and their time differential values as state variable vectors. (However, the matrix A has 8 rows and 8 columns, and the matrix B has 8 rows and 1 column.) According to the theory of the optimal regulator, the gain matrix K that converges the state variable vector size to 0 can be determined. . Actual vibration suppression control is the same as in the case of FIG.

Calculation of estimated wheel torque In the feedback control part of the vibration damping controller shown in FIG. 2 (B), the wheel torque input as disturbance to the feedforward control part is ideally provided with a torque sensor for each wheel. However, as described above, since it is difficult to provide a torque sensor for each wheel of a normal vehicle, a wheel torque estimator (from other detectable values in a running vehicle ( The estimated wheel torque estimated in C6) is used.

The wheel torque estimated value Tw is typically obtained by using a wheel rotational speed ω obtained from a wheel speed sensor of a driving wheel or a time derivative of a wheel speed value r · ω,
Tw = M · r ² · dω / dt (5)
Can be estimated. Here, M is the mass of the vehicle, and r is the wheel radius. [If the sum of the driving forces generated at the contact points of the driving wheels on the road surface is equal to the overall driving force MG (G is acceleration) of the vehicle, the wheel torque Tw is
Tw = M · G · r (5a)
Given in The acceleration G of the vehicle is obtained from the differential value of the wheel speed r · ω,
G = r · dω / dt (5b)
Therefore, the wheel torque is estimated as shown in Equation (5). ]

Correction of Estimated Wheel Torque Value In the estimation of wheel torque as described above, when the driving wheel tire grips the road surface and generates driving force while the vehicle is traveling forward, Equation (5) is It is expected that it is almost the same as the wheel torque actually generated. However, when the road surface reaction force on the driving wheel increases and exceeds the maximum friction circle, the tire enters a slip state (the tire slips), and the equation (5b) does not hold. The accuracy of the estimated value will deteriorate. In addition, with the exception of some high-function sensors, the magnitude of the rotational speed of the wheel can be detected from the signal from the wheel speed sensor normally mounted on the wheel, but whether the wheel is rotating forward or backward. You cannot get information about what you are doing. Therefore, the vibration suppression controller is normally configured on the assumption that the vehicle is moving forward. However, when the vehicle is moving backward, the above estimated value is directly input to the vibration suppression controller. If this occurs, the wheel torque is input to the vibration suppression controller in the opposite direction from the actual one. Furthermore, even when the wheel speed cannot be accurately detected, such as when the wheel speed sensor is broken, the accuracy of the estimated wheel torque of equation (5) also deteriorates.

Therefore, in the present invention, in the situation where the estimation accuracy of the wheel torque estimated value by the wheel torque estimator (C6) is deteriorated as described above, the correction of the wheel torque estimated value is performed as shown in the following equation (6). Is done.
Tw = κslip · κsign · M · r ² · dω / dt (6)
Here, κslip is a quantity given as a function of the wheel slip state quantity, and is given using a map as shown in FIG. Further, κsign is κsign = 1 during the forward rotation of the wheel, and κsign = −1 during the reverse rotation of the wheel.

  As understood from FIG. 4, κ slip in the correction formula (6) of the wheel torque estimated value is set to κ slip = 1 when the tire is in the grip state, and when the tire is in the slip state, It is reduced according to an arbitrary index (a wheel slip state amount) indicating the slip state of the vehicle (κslip = 0 in a state where the wheel is completely spun (a state where no wheel torque is applied to the vehicle)). When the tire of the driving wheel is slipped, the value of the acceleration G calculated by time differentiation of the wheel speed in the equation (5b) becomes larger than the actual acceleration, and therefore the wheel estimated from the wheel speed. The estimated torque value is expected to be larger than the actual value. Therefore, when the tire of the drive wheel is in a slip state, the wheel torque estimated value Tw is corrected downward by multiplying by κslip.

  The wheel slip state quantity that is an index representing the degree of slip of the wheel tire may be, for example, a ratio of the average value of the wheel speeds of the left and right driven wheels to the average value of the wheel speeds of the left and right drive wheels. In this case, when the driving wheel is in the slip state, the wheel speed of the driving wheel relatively increases, and as a result, the ratio of the wheel speed, that is, the wheel slip state amount is reduced. Further, the tire slip ratio and the slip ratio may be used as the wheel slip state quantity. When the wheel slip state quantity is defined as a value that increases as the degree of slip increases, the wheel slip state quantity increases and the value of κslip is reduced. As shown in the example of FIG. If the slip state quantity is defined as a value that decreases as the degree of slip increases, the wheel slip state quantity should be reduced and the value of κslip should be reduced. It should be understood that it belongs to the scope.

The correction of the estimated wheel torque value in equation (6) by κslip may be made by monitoring the value of the wheel slip state quantity. However, when the following conditions (a)-(c) are satisfied, the wheel It may be executed based on the value of the slip state quantity.
(A) When VSC, TRC, or ABS control is executed (when these controls are executed, it is usually when the tire transitions from the grip state to the slip state).
(B) The difference between the average value of the wheel speeds of the left and right driven wheels and the average value of the wheel speeds of the left and right drive wheels exceeds a predetermined amount for a predetermined period.
(C) When the time differential value of the wheel speed exceeds a predetermined threshold for a predetermined time. Note that the predetermined threshold may be set to an acceleration that cannot be generated by the vehicle.

  The slip state amount calculation unit that calculates the wheel slip state amount is in the braking control device 50b (FIG. 1B), and the wheel torque correction unit that performs correction by κ slip is in the drive control device 50a (FIG. 1B). , Respectively, by the operation of the CPU and other components. Since the control system of the present embodiment is a linear system, it is understood that the control amount of the drive torque that is the control output is corrected by correcting the estimated wheel torque value that is the control input. Should be.

As described above, the value of κsign in the equation (6) is set to κsign = −1 during the reverse rotation of the wheel. As already mentioned, the normal wheel speed sensor cannot detect the direction of the wheel.
(D) If it is an automatic vehicle, the shift lever of the transmission is in the R range,
(E) If it is a manual vehicle, it may be detected when the reverse switch is ON. If the wheel speed sensor mounted on the wheel can detect the rotational direction of the wheel, the formula (6) ) May be used.

By the way, when an abnormality occurs in the wheel speed sensor and the detection accuracy of the wheel speed is deteriorated, the accuracy of the estimated wheel torque according to the equation (5) or (6) is also deteriorated. The wheel rotation speed or wheel speed may be calculated from the rotation speed of the drive device. When the rotational speed Ne of the output shaft of the engine or motor of the driving device is used, the wheel rotational speed of the driving wheel is
ωe = Ne × transmission (transmission) gear ratio × diff (differential gear) gear ratio (7)
Given by. Moreover, when using the rotational speed No of the output shaft of the transmission,
ωo = No x differential gear ratio (8)
Given by. Then, the estimated value of the wheel rotational speed ω of the drive wheel in Expression (7) or (8) is substituted into Expression (6), and the estimated wheel torque value is calculated.

The calculation of the wheel torque estimated value by the equation (7) or (8) may be executed when any of the following conditions (f)-(i) is satisfied, for example.
(F) When an abnormality occurs in the signal of the wheel speed sensor and it is determined that the state is “abnormal”.
(G) When the abnormality of the wheel speed sensor is determined in the braking control device 50b (FIG. 1B).
(H) When the difference between the wheel speed calculated from the signal from the wheel speed sensor and the wheel speed calculated from the rotational speed of the output shaft of the driving device by the equation (7) exceeds a predetermined value for a predetermined period. .
(I) When the difference between the wheel speed calculated from the signal from the wheel speed sensor and the wheel speed calculated from the rotational speed of the output shaft of the transmission according to equation (8) exceeds a predetermined value for a predetermined period. .
In the present embodiment, the abnormality of the wheel speed sensor is detected in a manner known to those skilled in the art as described above, and a signal indicating this is transmitted from the braking control device 50b to the drive control device 50a. The

Correction of vibration suppression control In the above calculation of the estimated wheel torque value, the wheel slip state amount indicating the degree of wheel slip is the operation of the braking control device such as ABS control, VSC, TRC, or VDIM as described above. It is not calculated when is prohibited. In this case, κslip in equation (6) is not calculated. Therefore, when the above-described various controls are not operable, the feedback gain FB in FIG. 2B is reduced or set to 0, and the input value of the estimated wheel torque value Tw to the motion model C4 is reduced or cut off. The Specifically, the feedback control gain FB is reduced when any of the following conditions (j)-(l) is satisfied.
(J) When ON / OFF switches for ABS control, VSC, and TRC are all OFF.
(K) When the ON-OFF switch for VDIM is OFF.
(L) When ABS control, VSC and TRC or VDIM are prohibited from operating due to an abnormality in the braking system.

Note that when the condition (j)-(l) is satisfied, the feedback control gain FB is typically set to FB = 0, but when the wheel speed is low, the possibility of slipping is low. The feedback gain FB is reduced so as to decrease as the wheel speed increases, for example,
FB = λ / ω (9)
May be set. Note that λ is a positive constant determined experimentally or theoretically. In this case, as the wheel speed increases, the value of FB becomes substantially zero.

  On the other hand, the correction of the control amount for the vibration suppression control based on the required drive torque converted from the driver's drive request, that is, the correction of the control amount by the feedforward control does not use the estimated wheel torque value (the motion model). Is a linear model), it may be executed as it is even if any of the above conditions (j)-(l) is satisfied. However, it cannot be detected whether or not the wheel is in a slip state, and if the wheel is in a slip state, an increase in driving torque will worsen the slip state. Therefore, the amplitude of the control amount for damping control may be reduced, or damping control itself may be stopped. For example, the amplitude of the control amount may be reduced as the wheel speed increases as in the case of the equation (9).

  Note that when none of the above conditions (j)-(l) is satisfied, the accuracy of the wheel torque estimated value is improved even if the correction of the wheel torque estimated value (equation (6)) is executed. Even when it is determined that it is not performed, the input of the estimated wheel torque value to the motion model C4 may be blocked. Further, as for the case where the wheel is in a slip state, when the degree of slip represented by the wheel slip state quantity is larger than a predetermined degree, for example, in the map of FIG. At this time, as indicated by a broken line, κslip = 0 may be set so that the wheel torque estimation value input to the motion model C4 is substantially cut off. Further, when the condition (a)-(i) is satisfied, U (t) = 0 may be set to stop execution of the vibration damping control (stopping the correction of the requested drive torque).

  Although the above description has been made in relation to the embodiment of the present invention, many modifications and changes can be easily made by those skilled in the art, and the present invention is limited to the embodiment exemplified above. It will be apparent that the invention is not limited and applies to various devices without departing from the inventive concept.

  Furthermore, the vibration suppression control in the above embodiment is a vibration suppression control using the theory of an optimal regulator assuming a sprung or sprung / unsprung motion model as a motion model. As long as the estimated value of wheel torque is used, it is also applied to those using a motion model other than those introduced here, or those that are controlled by a control method other than the optimal regulator. Are also within the scope of the present invention.

FIG. 1A shows a schematic diagram of an automobile in which a preferred embodiment of a vibration damping control device according to the present invention is realized. FIG. 1B is a more detailed schematic diagram of the internal configuration of the electronic control device of FIG. 1A. FIG. 2A is a diagram for explaining the state variables of the vehicle body vibration that are suppressed in the vibration damping control device that is one of the preferred embodiments of the present invention. FIG. 2B is a diagram showing the configuration of the vibration damping control in the preferred embodiment of the present invention in the form of a control block diagram. FIG. 3 is a diagram for explaining a mechanical motion model of vehicle body vibration assumed in the vibration damping control device according to the preferred embodiment of the present invention. FIG. 3A shows a case where a sprung vibration model is used, and FIG. 3B shows a case where a sprung / unsprung vibration model is used. FIG. 4 is a graph showing a map of the correction coefficient κslip for the estimated wheel torque value that changes according to the wheel slip state quantity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle body 12FL, FR, RL, RR ... Wheel 14 ... Accelerator pedal 20 ... Drive device 30FL, FR, RL, RR ... Wheel speed sensor 50 ... Electronic control device 50a ... Drive control device 50b ... Braking control device 52 ... Switch

Claims (5)

  A vehicle vibration control device that suppresses pitch or bounce vibration of the vehicle by controlling a drive output of the vehicle, the wheel torque acting on a wheel generated at a contact point between the wheel of the vehicle and a road surface A wheel torque estimated value acquisition unit for acquiring an estimated value, a drive torque control unit for controlling the drive torque of the vehicle so as to suppress the pitch or bounce vibration amplitude based on the wheel torque estimated value, and a slip of the wheel. A slip state amount acquisition unit that acquires a wheel slip state amount indicating a slip state of the wheel from the braking control device of the vehicle for reducing the driving torque based on a degree of slip represented by the wheel slip state amount When the braking control device is not in an operable state, the braking control device can be operated. Damping control system for a vehicle, characterized in that compared to the state to reduce a control amount of the driving torque.   The apparatus according to claim 1, wherein a control amount of the drive torque by the drive torque control unit is determined based on the wheel torque estimated value and a drive request amount by a driver of the vehicle, and the brake control device is activated. When not in a possible state, the control amount of the driving torque based on the estimated wheel torque value is reduced to substantially zero.   2. The apparatus of claim 1, wherein the braking control device is at least one selected from the group consisting of ABS control, VSC, and TRC that are selectively operable by a driver of the vehicle. A device that reduces the control amount of the driving force when the braking control device is not in an operable state by the driver's selection as compared to when the braking control device is in an operable state. The apparatus according to claim 1, wherein the braking control device is part of a device that integrally controls behavior stability of a vehicle that is selectively operable by a driver of the vehicle. A device for reducing the control amount of the driving torque when the device for comprehensively controlling the behavioral stability of the vehicle is not operable by the driver's selection.   2. The device according to claim 1, wherein when the braking control device is not in an operable state due to an abnormality in the braking device of the vehicle, the driving is performed as compared with when the braking control device is in an operable state. A device characterized by reducing a control amount of torque.

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