JP2002283879A - Acceleration/deceleration control system of vehicle mounting continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an initial response of acceleration when a running state is restored to a high μ road from a low μroad. SOLUTION: When an engine and a continuously variable transmission are controlled by calculating an operational volume required to adjust an acceleration estimation value αwf to coincide with a target acceleration a αw * through a model following control means which uses a state-space method, the slipping state of a driving wheel is detected(4f) and a state feedback gain is switched coping with the slipping state of the driving wheel, and when the driving wheel changes from a slipping state to a non-slipping state, the initial value of integrated means 4b is reset to 0. Thus, a useless integrated value is reset to 0 even when running is shifted to a high μ road from a low μ road while the integrated value of the integrated means 4b is increasing on the low μ road. The responsiveness of controlling amount (such as acceleration, the rotational rate of a primary pulley) after the shift of the high μroad can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the acceleration / deceleration of a vehicle having a continuously variable transmission.

[0002]

2. Description of the Related Art As a model following control device using a state space method, as shown in FIG. 17, a state quantity x (t) of a control target, a state quantity xm (t) of a reference model, and an output of a reference model are output. deviation e (t) between ym (t) and the output y (t) of the control object
A model-following servo controller that defines an augmented system that uses all of the integral values as state variables and improves robustness by applying state feedback is known (for example, "Guidance and control in aerospace" Nishimura, Kanai and Murata, Corona pp 101-103).

Further, as a specific application example of the model following control, there is a driving force control device for a vehicle provided with a continuously variable transmission such as a CVT (for example, see Japanese Patent Application Laid-Open No. H11-10).
No. 5584). In this device, while satisfying the engine operating point constraint condition determined based on the optimal fuel consumption (efficiency) operation line of the engine or the engine brake characteristic line at the time of fuel cut, that is, the relationship between the engine torque and the engine rotation speed, the first Feedback that calculates the engine torque command value and the gear ratio command value of the continuously variable transmission required to make the estimated driving force match the target driving force, which is the target, and controls them separately to achieve the two command values simultaneously A compensator is configured.

[0004]

However, when the vehicle enters a low μ road from a high μ road by using these systems, it is conceivable that the driving wheel speed and the acceleration are largely hunted. As a countermeasure, it is conceivable to switch to a slip (for low μ road) state feedback gain when a slip state is detected. However, the maximum acceleration that can be achieved when traveling on a low μ road is higher than when traveling on a high μ road. As a result, the integrated value of the deviation between the target acceleration and the actual acceleration tends to increase, and the initial response of the acceleration when the vehicle returns to the high μ road is deteriorated.

An object of the present invention is to improve the initial response of acceleration when returning from a low μ road to a high μ road.

[0006]

The present invention will be described with reference to FIGS. 1 and 9 showing an embodiment of the present invention. (1) The invention of claim 1 includes a vehicle speed detecting means 8 for detecting a vehicle speed. Acceleration estimation means 4 for estimating the acceleration of the vehicle based on the detected vehicle speed, target acceleration setting means 4 for setting a target acceleration αw ^{* of the} vehicle, and an acceleration estimation value by a model following control method using the state space method. A control means 4 for controlling the engine 1 and the continuously variable transmission 3 by calculating an operation amount for making αwf equal to the target acceleration αw ^* , a standard for inputting the target acceleration αw ^* and outputting an acceleration command value αref. A model means 4a, an integrating means 4b for integrating a deviation between the acceleration command value αref and the estimated acceleration value αwf, and an integrating means 4b
Control means 4 having state feedback means 4c for calculating an operation amount by using the output of the control unit, and slip state detection means 4f for detecting a slip state of the drive wheel, and a state feedback gain according to the slip state of the drive wheel. And when the drive wheels change from the slip state to the non-slip state, the initial value of the integrating means 4b is reset to zero. (2) The invention according to claim 2 is a vehicle speed detecting means 8 for detecting a vehicle speed, an acceleration estimating means 4 for estimating a vehicle acceleration based on a detected vehicle speed value, and a target acceleration setting for setting a target acceleration αw ^{* of the} vehicle. Means 4, a rotational speed detecting means 11 for detecting a rotational speed of the input shaft of the continuously variable transmission, a target rotational speed setting means 4 for setting a target rotational speed of the input shaft of the continuously variable transmission,
The continuously variable transmission input torque command value Tp ^* and the gear ratio command value Ip ^* for matching the estimated acceleration value αwf to the target acceleration αw ^* by the model following control method using the state space method ^.
Is a control means 4 for controlling the engine 1 and the continuously variable transmission 3 by inputting a target acceleration αw ^* and inputting an acceleration command value α
reference model means 4a for outputting ref, and an acceleration command value αr
a first integrating means 4b for integrating a deviation between ef and the estimated acceleration value αwf, a second integrating means 4e for integrating a deviation between a target rotation speed of the input shaft of the continuously variable transmission and a detected rotation speed, 1
And second integrating means 4b, the control unit 4 and a state feedback unit 4c for calculating a speed change ratio command value Ip ^* and CVT input torque command value Tp ^* using the output of 4e
And a slip state detecting means 4f for detecting a slip state of the drive wheel. The state feedback gain is switched according to the slip state of the drive wheel, and the first state is set when the drive wheel changes from the slip state to the non-slip state.
And reset the initial values of the second integrating means 4b and 4e to zero. (3) The acceleration / deceleration control device for a vehicle equipped with the continuously variable transmission according to claim 3, when switching the state feedback gain, sets the initial value of the integrating means 4b so that the operation amount changes continuously before and after the switching. An initial value setting means 4 for setting is provided. (4) The acceleration / deceleration control device for a vehicle including the continuously variable transmission according to claim 4, wherein the first and second integrations are performed such that when the state feedback gain is switched, the operation amount continuously changes before and after the switching. An initial value setting means 4 for setting initial values of the means 4b and 4e is provided. (5) An acceleration / deceleration control device for a vehicle equipped with a continuously variable transmission according to claim 5 switches the state feedback gain K based on a detected vehicle speed and an input torque of the continuously variable transmission.

In the section of the means for solving the above-described problem, a diagram of one embodiment is used for easy understanding of the description, but the present invention is not limited to this embodiment. .

[0008]

(1) According to the first aspect of the present invention, the operation amount for matching the estimated acceleration value to the target acceleration is calculated by the model following control method using the state space method, and the engine is continuously variable. When controlling the transmission, the slip state of the drive wheel is detected, the state feedback gain is switched according to the slip state of the drive wheel, and when the drive wheel changes from the slip state to the non-slip state, the integration means is initialized. Since the value is reset to 0, the useless integral value is reset to 0 even if the integral value of the integrating means is increased while traveling on a low μ road, and the integral value is reset to 0. Responsiveness of the control amount (for example, acceleration or primary pulley rotation speed) after entering can be improved. (2) According to the second aspect of the present invention, the continuously variable transmission input torque command value and the gear ratio command value for matching the estimated acceleration value with the target acceleration are calculated by the model following control method using the state space method. When controlling the engine and the continuously variable transmission, the slip state of the drive wheel is detected, the state feedback gain is switched according to the slip state of the drive wheel, and the drive wheel changes from the slip state to the non-slip state. In such a case, the initial values of the first and second integrating means are reset to 0. Therefore, even when the integrated value of the integrating means is increased while the vehicle is running on a low μ road, a change to a high μ road is useless. The integral value is reset to 0, and the responsiveness of the control amount (for example, acceleration and primary pulley rotation speed) after entering the high μ road can be improved. (3) According to the third and fourth aspects of the present invention, when the state feedback gain is switched, the initial value of the integrating means is set so that the manipulated variable continuously changes before and after the switching. The manipulated variable continuously changes before and after the gain switching, and the response of the feedback control system is not disturbed. (4) According to the fifth aspect of the present invention, the state feedback gain is switched based on the vehicle speed detection value and the continuously variable transmission input torque. Therefore, the non-linear control is performed as in a vehicle having a continuously variable transmission. Even in the case of a target, stable and fast-response control performance can be realized in a wide vehicle speed range and a wide torque range.

[0009]

FIG. 1 is a diagram showing the configuration of an embodiment. A power train of a vehicle according to one embodiment includes an engine 1, a torque converter 2 with a lock-up clutch, and a continuously variable transmission (CVT) 3. The engine 1 includes an intake air amount control by an electronically controlled throttle valve actuator (not shown), a fuel injection control by an injector (not shown), and an ignition device (not shown).
, The engine torque is controlled.

The lock-up clutch of the torque converter 2 with a lock-up clutch is released only in an extremely low speed range to enable the vehicle to stop and start, and to further dampen vibration. On the other hand, in the middle to high speed range, the lock-up clutch is engaged to improve the transmission efficiency. The continuously variable transmission 3 adjusts the effective radii of the primary pulley and the secondary pulley on which the belts are stretched by a hydraulic mechanism (not shown) to make the speed ratio variable. The continuously variable transmission 3 is not limited to a belt type, and may be, for example, a toroidal type.

The acceleration / deceleration controller 4, the engine torque controller 5, and the CVT & clutch controller 6 are respectively a microcomputer, a ROM,
Peripheral circuits such as a RAM, an A / D converter, and various timers, a communication circuit, and a drive circuit for various actuators are provided, and communicate with each other via a high-speed communication line 13.

The acceleration / deceleration controller 4 performs a band-pass filter process on the detected vehicle speed to calculate the vehicle acceleration αwf
Estimating a, as an acceleration detection value of the acceleration estimate Arufawf, fed back to the reference model output αref for calculating the desired response of the acceleration estimate Arufawf for target acceleration .alpha.w ^*, performs acceleration feedback control. The acceleration / deceleration controller 4 includes an accelerator sensor 7 for detecting an amount of depression of an accelerator pedal (hereinafter, referred to as an accelerator opening) Apo, and peripheral speeds (hereinafter, wheel speed and vehicle body) of drive wheels 14 and driven wheels (not shown). The speed is connected to a wheel speed sensor 8 for detecting Vw and Vb.

The engine torque controller 5 controls the torque of the engine 1 by controlling the amount of intake air, controlling fuel injection, and controlling ignition timing. A crank angle sensor 9 for detecting the rotation speed ωe of the engine 1 is connected to the engine torque controller 5. The CVT & clutch controller 6 controls a hydraulic mechanism (not shown) to control the speed ratio of the continuously variable transmission 3. The CVT & clutch controller 6 has a primary speed sensor 10 for detecting the rotation speed ωp of the primary pulley of the continuously variable transmission 3 and the rotation speed ωs of the secondary pulley.
Is connected to a secondary speed sensor 11 for detecting the speed.

FIG. 2 is a flowchart showing an acceleration control program according to one embodiment. The operation of the embodiment will be described with reference to this flowchart. The microcomputer of the acceleration / deceleration controller 4 executes this control program at predetermined time intervals, for example, every 10 msec.

In step 1, the accelerator sensor 7
The accelerator opening Apo is read from. In step 2, a pulse signal from the wheel speed sensor 8 is measured to detect a peripheral speed of the driving wheel 14 and the driven wheel with respect to the effective radius R of the tire, that is, a wheel speed Vw and a vehicle body speed Vb. Note that high μ
During road running, the wheel speed Vw and the vehicle speed Vb are equal.

In step 20, a slip state is determined using the wheel speed Vw and the vehicle speed Vb detected in step 2. The slip state is determined as follows.
If the state in which the slip ratio (= | Vb−Vw | / Vb) is greater than the predetermined value α1 continues for a predetermined period of time Ton1, it is determined that the vehicle is in the slip state, and the state in which the slip ratio is smaller than the predetermined value β1 (<α1) is the predetermined time If Toff1 (> Ton1) or more continues, it is determined that the slip state has been eliminated. The slip state may be determined using the slip amount (= | Vb-Vw |) instead of the slip ratio. That is, if the state in which the slip amount is larger than the predetermined value α2 continues for the predetermined time Ton2 or longer, it is determined that the vehicle is in the slip state, and the state in which the slip amount is smaller than the predetermined value β2 (<α2) is the predetermined time Toff2 (>).
Ton2) If it continues for more than this, it is determined that the slip state has been resolved. The determination method of the slip state is not limited to the determination method of this embodiment, and many other methods can be used. At the time of slip, 1 is set to the slip flag fs, and at the time of non-slip, 0 is set.

In the following step 3, the continuously variable transmission 3 is transmitted from the CVT & clutch controller 6 via the high-speed communication line 13.
The rotation speed ωp of the primary pulley (input shaft), the rotation speed ωs of the secondary pulley (output shaft), and the speed ratio Ip (= ωp / ωs) are read from the engine 1 via the high-speed communication line 13 from the engine torque controller 5. Read the rotation speed ωe of.

In step 4, a target acceleration αw ^* is calculated based on the accelerator opening Apo and the wheel speed Vw. Specifically, a map of the target acceleration αw ^* with respect to the accelerator opening Apo and the wheel speed Vw as shown in FIG.
A target acceleration αw ^* with respect to the detected accelerator opening Apo and wheel speed Vw is calculated by lookup. When the vehicle speed is being controlled, the target acceleration αw ^* is set in accordance with a target vehicle speed setting operation such as a set switch, an accelerator switch, or a coast switch.

In step 5, a band pass filter process is performed on the wheel speed Vw to calculate an estimated acceleration value αwf.
Hereinafter, a method of calculating the estimated acceleration value αwf will be described.

First, a transfer function Gbp (s) of a continuous time system in which the wheel speed Vw is input and the estimated acceleration value αwf is output is described as follows.

(Equation 1) In the expression (1), s is a Laplace operator, ωn is a natural angular frequency, Δn is an attenuation rate, and ωn and Δn are determined according to a noise level included in the detected wheel speed value Vw.

Next, when this transfer function Gbp (s) is converted into a representation by a state vector, it is represented by a block diagram shown in FIG. 4, and a state equation and an output equation using the state variable vector xf are as follows. Is described.

(Equation 2) In the equation (2), Af, Bf, Cf, and Df are constant matrices determined from the natural angular frequency ωn and the attenuation rate ζn.

In order to calculate the internal state variable vector xf of the bandpass filter in addition to the estimated acceleration value αwf which is the output of the bandpass filter, the state equation and the output equation of the continuous time system shown in the equation (2) are used. Perform the operation. If the integration operation is Euler integration in order to design a state feedback compensator for acceleration control in a continuous time system, the state equation and the output equation of the above equation (2) can be actually executed by microcomputer software. It can be expressed as a simple difference equation as follows.

(Equation 3) In the equation (3), Tsmp is a sampling period,
In this embodiment, it is 10 msec. Also, (k) indicates the current value, and (kn) indicates the value before n sampling periods.
The estimated acceleration value αwf is obtained by executing the equation (3).

In step 6, the engine torque command value T
A simple first-order lag model from e ^* to the actual engine torque Te is used to estimate the actual engine torque Te with respect to the engine torque command value Te ^* . First, the transfer function Geng (s) of the continuous time system from the engine torque command value Te ^* to the actual engine torque Te is described as follows.

(Equation 4) In the equation (4), Teng is a time constant.

Equation (4) is discretized by Tustin approximation or the like, and a difference equation that can be actually executed by software of a microcomputer is obtained and executed.

(Equation 5) In equation (5), TEN0, TEN1, and TED1 are time constants Teng
And the sampling period Tsmp.

In step 7, an engine rotational speed ωe corresponding to the estimated engine torque Te is looked up from a preset engine operating point constraint line map as shown in FIG. Engine Operating Point Constraint Line Map In FIG. 5, the engine optimal fuel economy operation line is used as a constraint line in a positive torque range, and the engine brake characteristic line is used as a constraint line in a negative torque range. Note that the engine optimum fuel consumption operation line is a characteristic line connecting engine operation points on the output line such as the engine where the fuel consumption is the smallest. The engine brake characteristic line is the engine operating point when the throttle valve is fully closed and the fuel is cut. By controlling along the engine brake characteristic line, the engine brake control during the downshift of the continuously variable transmission 3 is performed. Enable.

Here, considering the state in which the lock-up clutch of the torque converter 2 is engaged, the engine rotation speed ωe is equal to the rotation speed ωp of the primary pulley (input shaft) of the continuously variable transmission 3. Therefore, the engine rotational speed ωe obtained by performing a lookup calculation from the map of FIG. 5 is set as a target primary pulley rotational speed (input shaft rotational speed of the continuously variable transmission) ωp ^* . Then, a value Z is calculated by integrating the deviation between the target primary pulley rotation speed ωp ^* and the actual rotation speed ωp of the primary pulley.

(Equation 6)

In step 8, an operation range determination for performing gain switching by acceleration feedback control is performed. In this embodiment, as shown in FIG.
The operating area is divided into six based on the value of w and the sign of the input torque Tp of the continuously variable transmission 3, and the gain K is switched. When the lock-up clutch of the torque converter 2 is engaged, the input torque Tp of the continuously variable transmission 3 is equal to the engine torque Te.

The gain K is set at the time of slip (flag fs =
Different values are set for 1) and when no slip occurs (fs = 0). In this embodiment, the non-slip gain when traveling on a high μ road is Kh, and the slip gain when traveling on a low μ road is Kl.
(<Kh). Then, the gain K is selected based on the divided region based on the wheel speed Vw and the input torque Tp of the continuously variable transmission and the presence or absence of slip. Thereby, at the time of a slip, the response of the control amount (acceleration, primary pulley rotation speed) can be made slow to suppress the influence of the slip.

If the operation region one sampling period before and the operation region in the current sampling period are the same region, the process proceeds to step 10, and if they are different, the process proceeds to step 9. In step 9, in preparation for switching the state feedback gain, the initial values of the two integrators in the feedback compensator for acceleration control are calculated. Specifically, from the state feedback gain constant matrix corresponding to each operation region stored in the ROM in advance, Kold corresponding to the operation region one sampling cycle before and Knew corresponding to the current operation region are selected. The initial value Xi_ini of the acceleration deviation integrator and the primary pulley rotation speed are determined by using the following equation obtained by solving the equation (15) of the state feedback calculation described later so that the compensator output U continuously changes before and after the gain switching. An initial value Zini of the deviation integrator is calculated.

(Equation 7) In equation (7), (k) indicates a value in the current sampling cycle, and (k-1) indicates a value one sampling cycle before.

However, in this embodiment, when the vehicle travels on a low μ road (slip state fs = 1) and changes to a high μ road (non-slip state fs = 0), an acceleration deviation integrator is used. The initial value Xi_ini and the primary pulley rotation speed deviation integrator Zini are both reset to zero. That is, the integral Xi of the acceleration deviation integrator and the integral Z of the primary pulley rotational speed deviation integrator are both reset to zero. As a result, the deviation integrated values Xi, Z
Even if the road changes to a high μ road while increasing, unnecessary deviation integral values Xi and Z are reset to 0, and the response of the control amount (acceleration, primary pulley rotation speed) after entering the high μ road is reduced. Can be improved.

In step 10, the operation of the acceleration control feedback compensator is performed. In this embodiment,
"Model following control", which is one of the practical linear control methods, is used. The control system design method will be described below.

First, a plant model for control system design is derived. The continuously variable transmission input torque command value Tp ^* shown in FIG.
The following equation shows a model obtained by linearly approximating a non-linear vehicle model having the input of the gear ratio command value Ip ^* and the estimated drive wheel acceleration value αwf and the primary rotational speed ωp at specific operating points (Tp0, Ip0, ωp0). .

(Equation 8) In equation (8) and FIG. 7, Te is the engine torque,
Tp is the input torque of the continuously variable transmission, Tine is the inertia torque, Ip is the transmission ratio of the continuously variable transmission, ωe is the engine speed,
ωp is the continuously variable transmission primary pulley rotation speed, ωw is the driving wheel rotation speed (Vw = R · ωw), Vw is the driving wheel speed,
αw is the drive wheel acceleration, M is the vehicle mass, R is the effective radius of the tire, If is the final gear ratio, T1 is the time constant of the engine torque system (= Teng), T2 is the time constant of the speed ratio servo system,
J1 is the inertia from the engine 1 to the primary pulley of the continuously variable transmission 3.

The linear approximation vehicle model represented by the equation (8) is expanded by combining a bandpass filter model represented by the equation (2) and a deviation integral model relating to the engine operating point constraint condition represented by the following equation (9). Let the system model be a plant model for control system design.

(Equation 9) In the equation (9), ka is a constant, which is obtained by linearly approximating a non-linear map relating to the engine operating point constraint condition at a specific point.

The plant model of the enlarged system is represented by a block diagram using the state vector shown in FIG. 8, and is described as follows in the form of a state equation and an output equation of a continuous time system.
However, when the lock-up clutch of the torque converter 2 is engaged, the input torque Tp of the continuously variable transmission 3 is equal to the engine torque Te.

(Equation 10) In the equation (10), the number of inputs is 2, the number of outputs is 1, and the number of states is 6, and Ap, Bp, Cp, and Dp are constant matrices. Also, T
p ^* is an input torque command value of the continuously variable transmission 3, and Ip ^* is a speed ratio command value of the continuously variable transmission 3. Further, xf1 and xf2 are:
This is an element of the internal state variable vector xf of the bandpass filter represented by the quadratic expression shown in Expression (1).

The estimated acceleration value αwf for the target acceleration αw ^*
Is defined as a first order lag, and its transfer function, state equation, and output equation are expressed as follows.

[Equation 11] In equation (11), Tαw is a time constant.

FIG. 9 shows a control block diagram in the case where an acceleration servo system is configured using the “model following control method by state feedback” for the above-described expanded system plant model and reference model. In FIG. 9, a thick line indicates a vector, and a thin line indicates a scalar.

By configuring such a compensator, the estimated acceleration value αwf matches the acceleration command value αref of the reference model output without a steady-state deviation. At the same time, all state variables are stabilized by state feedback.
That is, since the integral value Z of the rotational speed deviation of the primary pulley (input shaft) of the continuously variable transmission 3, which is one of the state variables, is stabilized, as a result, the target rotational speed ωp of the primary pulley of the continuously variable transmission 3 is obtained. ^The actual rotation speed ωp matches ^* without a steady-state deviation.

The state feedback gain K shown in FIG.
The (constant matrix) is obtained by using a general “optimum regulator method” or the like with respect to the combined model shown in FIG. 10 in which the above-described expanded plant model and reference model are further combined. However, the acceleration command value αref of the reference model output
And the integral of the deviation between the estimated acceleration αwf and Xi.

(Equation 12)

Next, the actual processing is represented in the form of a difference equation executable by software of the microcomputer.
First, the calculation of the reference model is performed by the following difference equation.

(Equation 13) In the equation (13), MAN0, MAN1, and MAD1 are the above (1)
It is a constant obtained by discretizing equation (1) by Tustin approximation or the like. Next, the acceleration deviation integral calculation is executed by the following difference equation.

[Equation 14] Further, the state feedback calculation is executed by the following equation.

(Equation 15) Then, the engine torque command value Te ^* is determined by the following equation.

(Equation 16) In equation (16), L is a function of the slip ratio of the torque converter when the lockup clutch of the continuously variable transmission 3 is not engaged. The engagement state and the non-engagement state of the lock-up clutch are detected by the CVT & clutch controller 6 and transmitted to the engine controller 5.

In step 11, upper and lower limiters are applied to the engine torque command value Te ^* and the gear ratio command value Ip ^* calculated by the acceleration control model following compensator, and the engine torque controller 5 and the CVT &
The values are limited to values achievable by the clutch controller 6, and are set as final engine torque command values Te ^* and speed ratio command values Ip ^* . In the following step 12, the engine torque command value Te ^* is sent to the engine torque controller 5,
Speed ratio command value Ip ^* is converted to CVT & clutch controller 6
Are output via the high-speed communication line 13 respectively. The engine torque controller 5 controls the engine torque Te to be the command value Te ^*, and the CVT & clutch controller 6 controls the speed ratio Ip of the continuously variable transmission 3 to be the target value Ip ^* .

Next, the parts related to the present invention in the above embodiment will be summarized and described. First, for the sake of simplicity, the description will be made on the assumption that Kl = Kh = K without switching the gain between the slip state and the non-slip state.

As described above, in the conventional acceleration / deceleration control device, when a linear controller based on the linear control theory is applied to a non-linear control object such as a vehicle having a continuously variable transmission, for example, as shown in FIG. Thus, the state feedback gains K1, K2, and K3 are independent of the internal state quantity of the servo controller, that is, the integral value of the deviation e (t) between the output ym (t) of the reference model and the output y (t) of the control object. Is controlled in the middle of the control, there is a problem that the operation amount, that is, the output u (t) of the controller changes suddenly before and after the gain is switched, and the response is disturbed and the control performance is deteriorated.

In order to solve such a problem of the conventional acceleration / deceleration control device, in this embodiment, a target acceleration and a target continuously variable transmission input shaft rotation speed (in this embodiment,
For an acceleration / deceleration control device for a vehicle equipped with a continuously variable transmission for simultaneously achieving the target engine rotational speed), two operation amounts (output values of a controller), that is, an engine torque command value Te ^* (lock) When the up clutch is engaged, Te ^* = Tp ^* ) and the gear ratio command value Ip ^* are changed in the model following controller so that they continuously change before and after the state feedback gain K is switched.
The first integrator (4b) that integrates the initial values of the integrators, that is, the deviation between the acceleration command value αref of the reference model (4a) output and the estimated acceleration value αwf of the output of the controlled plant (4d) shown in FIG. ), The target rotational speed ωp ^{* of the} input shaft of the continuously variable transmission, and the detected rotational speed ω.
integral value Z of the second integrator (4e) for integrating the deviation from p
Is set when the state feedback gain K is switched.

In order to perform the "acceleration control using the model following control method", in step 10, the state feedback shown in the equation (14) is obtained by using the state feedback gain matrix Knew corresponding to the operation region shown in FIG. Perform the operation. When the operating point continues to be in the same operating region, continuous control is performed using the same feedback gain matrix. However, when shifting to another operating point, the feedback gain matrix is changed from Kold to Knew. since switches, control CVT input torque command value of the operation amount becomes discontinuous Tp ^* (when CVT lockup clutch engagement is Tp ^* = Te ^*) and the speed ratio command value Ip ^* is suddenly changed You have to do it.

In one embodiment, when it is determined in step 8 that the operating range is switched, in step 9 the output (operation amount) of the acceleration feedback compensator, that is, the input torque command value Tp ^{* of the} continuously variable transmission and the speed change As the ratio command value Ip ^* changes continuously before and after the switching of the gain matrix K,
The initial value of the integrator in the compensator, that is, the initial value of the integrated value of the acceleration deviation Xi and the integrated value of the input shaft rotational speed deviation integrated value Z of the continuously variable transmission is calculated.

Specifically, it is calculated by the following equation (7), which is obtained by solving the following equation with [Z (k), Xi (k)].

[Equation 17]

FIGS. 11 and 12 show simulation results of the acceleration / deceleration control device according to the embodiment. In addition,
The numbers at the bottom of FIGS. 11 and 12 represent the operating region numbers shown in FIG. When the lock-up clutch of the torque converter 2 is engaged, the input torque command value Tp ^* of the continuously variable transmission (CVT) 3 is equal to the engine torque command value Te ^* .

FIG. 11 shows a response result of the conventional acceleration / deceleration control device when the initial value of the integrator in the acceleration feedback compensator is not reset when the state feedback gain is switched. Input torque command value of the continuously variable transmission 3 of the acceleration feedback compensators outputs before and after the gain switching Tp ^* (CVT lockup clutch engagement time Tp ^*
= Te ^* ) and the gear ratio command value Ip ^* change greatly, and the response waveforms of the acceleration αwf and the primary pulley rotation speed ωp are greatly disturbed.

On the other hand, FIG. 12 shows a response result when the initial value of the integrator in the acceleration feedback compensator is set when the state feedback gain is switched, that is, the response result of the acceleration / deceleration control device of the above-described embodiment. Before and after the gain switching, the input torque command value Tp ^{* of the} continuously variable transmission 3 (Tp ^* = Te ^* when the continuously variable transmission lock-up clutch is engaged) and the speed ratio command value Ip ^{* of the} continuously variable transmission 3 with the output of the acceleration feedback compensator do not suddenly change. It changes continuously and follows the target value well without disturbing the response waveforms of the acceleration αwf and the primary pulley rotation speed ωp.

As described above, in one embodiment described above,
In an acceleration / deceleration control device for a vehicle having a continuously variable transmission for simultaneously achieving a target acceleration and a target continuously variable transmission input shaft rotation speed, two operation amounts, that is, a continuously variable transmission input torque command value Tp ^* ( The reference model output in the model following controller such that Tp ^* = Te ^* ) when the continuously variable transmission lock-up clutch is engaged and the gear ratio command value Ip ^* change continuously before and after the state feedback gain K is switched. Initial value Xi_ini of the deviation integral value Xi between the acceleration command value αref of the control target output and the estimated acceleration value αwf of the control target output, and the deviation integral value Z of the target rotational speed ωp ^* and the rotational speed detection value ωp of the continuously variable transmission input shaft. Is set when the state feedback gain K is switched. As a result, the manipulated variables Te ^* and Ip ^* continuously change before and after the switching of the state feedback gain, so that the response of the feedback control system is not disturbed. Therefore, since the switching of the state feedback gain can be relatively freely performed, even in a non-linear control target such as a vehicle having a continuously variable transmission such as a CVT, a stable and fast response control performance can be achieved in a wide operating range. Can be realized.

In the above-described embodiment, the state feedback gain K is determined based on the wheel speed Vw (corresponding to the vehicle speed) and the continuously variable transmission input torque Tp (Tp = Te when the continuously variable transmission lock-up clutch is engaged). Switch. Wheel speed Vw
And the input torque Tp of the continuously variable transmission greatly change, so that when the nonlinear vehicle model shown in FIG. 7 is linearly approximated as shown by the equation (8), the influence by the modeling error is not increased. In one embodiment, these two
The gain of the linear compensator is switched based on the two vehicle state quantities Vw and Tp.

Further, the control system design model shown in the equation (10) includes the primary pulley rotation speed deviation integral model shown in the equation (6). That is, since it includes the gradient ka (see equation (9)) of the engine operating point constraint line map shown in FIG. 5, in the positive torque region using the optimal efficiency operation line and the negative torque region using the engine braking characteristic line, The sign of the slope ka always switches. Therefore, the effect of the linear modeling error caused by this is large, and it is necessary to switch the state feedback gain K corresponding to the sign of the continuously variable transmission input torque Tp.

As described above, according to this embodiment,
Since the state feedback gain K is switched based on the wheel speed Vw and the continuously variable transmission input torque Tp (= engine torque Te), even if the vehicle is a non-linear control target such as a vehicle equipped with a continuously variable transmission, It is possible to realize stable and quick response control performance in a wide vehicle speed range and a wide torque range.

<< Gain Switching by Slip Judgment >> Next, a case where the slip state gain Kl and the non-slip state gain Kh are switched based on the judgment of the slip state or the non-slip state (4f in FIG. 9) will be described.

As described above, the state feedback gain K is adjusted so that the plant operation amount (Te ^* , Ip ^* ) continuously changes before and after the switching of the state feedback gain K.
By simply setting the initial values (Xi_ini, Zini) of the integrators (4b, 4e) in the model following controller at the time of switching, the following problem remains because the state of the road surface is not considered.

That is, when the vehicle enters the low μ road from the high μ road, there is a possibility that the driving wheel speed or the acceleration is largely hunted. Therefore, the slip of the drive wheel is determined, and when the vehicle is slipping, the state is switched to the slip state feedback gain Kl which is smaller than the non-slip state feedback gain Kh. Thereby, the response of the control amount (acceleration, primary pulley rotation speed) can be made slow, and the influence of the slip can be suppressed.

However, when traveling on a low μ road, the maximum acceleration that can be achieved is limited according to the road surface condition, so that it is more difficult to achieve the target acceleration than when traveling on a high μ road. In this situation, the integrated value Xi of the deviation from the acceleration is easily increased. Then, the increased deviation integral value Xi deteriorates the initial response of the acceleration and the primary pulley rotation speed when returning to the next high μ road.

Therefore, as described above, in this embodiment, when the vehicle changes to a high μ road (non-slip state fs = 0) while traveling on a low μ road (slip state fs = 1), The initial value Xi_ini of the acceleration deviation integrator and the Zini of the primary pulley rotation speed deviation integrator are both reset to zero. That is, the integral Xi of the acceleration deviation integrator and the integral Z of the primary pulley rotational speed deviation integrator are both reset to zero. Thereby, even when the deviation integral values Xi, Z increase while driving on a low μ road, the unnecessary deviation integral values Xi, Z are reset to 0 even if the deviation integral value Xi, Z changes to a high μ road,
Responsiveness of the control amount (acceleration, primary pulley rotation speed) after entering the high μ road can be improved.

In an acceleration control system for a CVT-equipped vehicle realized by model following control using the state space method, when the road surface changes to a low μ road when traveling on a high μ road (fs = 0), the wheel speed is reduced. However, there is a problem that the hunting greatly increases in both the acceleration and the acceleration. Furthermore, it is more difficult to achieve the target acceleration αw ^* when traveling on a low μ road than when traveling on a high μ road, and the integrated value of the deviation between the target acceleration αw ^* and the estimated acceleration value αwf tends to increase. When the road surface changes to a high μ road in a situation where the deviation integral value is increasing, there is also a problem that the acceleration responsiveness immediately after shifting to the high μ road deteriorates.

In the above-described embodiment, the state feedback gain Kh for the high μ road and the state feedback gain Kl for the low μ road are prepared, and when the slip of the driving wheel is detected, the state feedback gain Kh is reduced from the high μ road gain Kh. Switch to low μ road gain Kl. Further, when the vehicle travels from a low μ road to a high μ road, the deviation integrated values for each of the control amounts (acceleration, primary rotation speed) are cleared to 0, thereby solving these problems.

FIGS. 13 to 16 show the results of the simulation of one embodiment. FIG. 13 shows changes in acceleration, primary pulley rotation speed, primary torque, gear ratio, drive wheel speed and vehicle speed when changing from a high μ road to a low μ road, and FIG. 13 shows switching to a low μ road state feedback gain Kl. FIG. 14 shows the case without the switching to the low μ road state feedback gain Kl. Figure 1
Comparing FIG. 3 with FIG. 14, when the road changes from the high μ road to the low μ road, the hunting observed in the vehicle speed and acceleration is switched by switching to the low μ road gain Kl which is smaller than the high μ road gain Kh. Can be reduced (10
Seconds).

FIGS. 15 and 16 show the relationship between the low μ road and the high μ road.
When the road changes, the integrated value of the deviation for each control amount is set to 0.
A case where no reset is performed (FIG. 15) and a case where zero reset is performed (FIG. 16) are shown. Comparing these figures, it can be confirmed that the acceleration response after shifting to the high μ road is improved (15 to 25 seconds).

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a flowchart showing an acceleration control program according to one embodiment.

FIG. 3 is a diagram showing an example of a map of a target acceleration αw ^* with respect to an accelerator opening Apo and a wheel speed Vw.

FIG. 4 is a diagram illustrating a transfer function Gbp (s) of a continuous time system using a wheel speed Vw as an input and an estimated acceleration value αwf as an output, as a state vector.

FIG. 5 is a diagram illustrating an example of an engine operating point constraint line map.

FIG. 6 is a diagram showing an example in which an operating region is divided based on the wheel speed Vw and the sign of the continuously variable transmission input torque Tp.

FIG. 7 is a diagram showing a non-linear vehicle model that receives a continuously variable transmission input torque command value Tp ^* and a gear ratio command value Ip ^* and outputs a drive wheel acceleration estimated value αwf and a primary pulley rotation speed ωp.

FIG. 8 is a diagram showing a plant model for control system design of an enlarged system.

FIG. 9 is a control block diagram in the case where an acceleration servo system is configured using a model following control method based on state feedback for an enlarged system plant model and a reference model.

FIG. 10 is a diagram showing a model obtained by combining an enlarged plant model and a reference model.

FIG. 11 is a diagram illustrating a response result of a conventional acceleration / deceleration control device when the initial value of the integrator in the acceleration feedback compensator is not reset when the state feedback gain is switched.

FIG. 12 is a diagram showing a case where an initial value of an integrator in an acceleration feedback compensator is set when a state feedback gain is switched, that is, a response result of the acceleration / deceleration control device according to the embodiment described above.

FIG. 13 shows a low μ road when the road changes from a high μ road to a low μ road.
It is a figure showing a simulation result of one embodiment in the case of not switching to road condition feedback gain Kl.

FIG. 14 shows a low μ road when the road changes from a high μ road to a low μ road.
FIG. 9 is a diagram illustrating a simulation result of the embodiment in a case where there is a switch to a road state feedback gain Kl.

FIG. 15 is a diagram showing a simulation result of an embodiment in a case where a deviation integrated value relating to each control amount is not cleared to 0 when changing from a low μ road to a high μ road.

FIG. 16 is a diagram illustrating a simulation result of an embodiment in which a deviation integral value regarding each control amount is cleared to 0 when the road changes from a low μ road to a high μ road.

FIG. 17 is a control block diagram showing conventional model following control.

[Explanation of symbols]

 Reference Signs List 1 engine 2 torque converter with lock-up clutch 3 stepless transmission 4 acceleration / deceleration controller 4a reference model 4b first integrator 4c state feedback 4d plant to be controlled 4e second integrator 5 engine torque controller 6 CVT & clutch controller 7 Accel sensor 8 Wheel speed sensor 9 Crank angle sensor 10 Primary speed sensor 11 Secondary speed sensor 13 High speed communication line 14 Drive wheel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 325 F02D 41/04 325G 41/10 325 41/10 325 45/00 314 45/00 314E 370 370B F16H 61/02 F16H 61/02 // F16H 59:06 59:06 59:18 59:18 59:44 59:44 59:66 59:66 63:06 63:06 (72) Inventor Masafumi Matsuyama Kanagawa F-term in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi (reference) 3D041 AA32 AA48 AB01 AC01 AC15 AC19 AD01 AD02 AD10 AD31 AD47 AD51 AE03 AE31 AF01 3G084 BA02 CA04 CA06 DA05 DA17 DA25 EA11 EB08 EB12 EB10 FA05 3G093 AA05 AA06 BA01 CB06 CB07 DA01 DA06 DB03 DB05 DB17 DB18 DB21 EA02 FA05 FA11 3G301 JA03 JA38 KA12 KA16 NA04 NA08 NA09 NB02 NB04 NB15 NC02 NC08 ND02 ND05 ND06 ND45 PE01A PE01Z PE06Z PF01Z PF02A PF02Z PF03Z PG00Z 3J552 MA07 MA09 MA12 NA01 NB04 PA32 RA27 RB26 SA34 SA44 SB01 TA02 TA10 TB17 UA02 UA08 VA11W VA12Z VA22Z VA32W VA32Y VA34W VA37Z VA74Z VA76Z VB01V VC03ZV02 VCB03Z VC02Z

Claims (5)

[Claims] A vehicle speed detecting means for detecting a vehicle speed, an acceleration estimating means for estimating a vehicle acceleration based on the detected vehicle speed value, a target acceleration setting means for setting a target acceleration of the vehicle, and a state space method. A control means for controlling an engine and a continuously variable transmission by calculating an operation amount for matching an estimated acceleration value to a target acceleration by a model following control method, wherein the target acceleration is input and an acceleration command value is output. Control means having reference model means, integrating means for integrating a deviation between the acceleration command value and the estimated acceleration value, and state feedback means for calculating the operation amount using an output of the integrating means; And a slip state detecting means for detecting a slip state of the drive wheel, and switching the state feedback gain according to the slip state of the drive wheel, and There deceleration control apparatus for a vehicle having a continuously variable transmission, characterized in that resetting the initial value of the integrating means to zero when the changes from the slip state to the non-slip state. 2. A vehicle speed detecting means for detecting a vehicle speed, an acceleration estimating means for estimating a vehicle acceleration based on a detected vehicle speed value, a target acceleration setting means for setting a target acceleration of the vehicle, and a continuously variable transmission input shaft. Rotation speed detection means for detecting the rotation speed of the motor, target rotation speed setting means for setting the target rotation speed of the input shaft of the continuously variable transmission, and an estimated acceleration value obtained by the model following control method using the state space method. Control means for controlling an engine and a continuously variable transmission by calculating a continuously variable transmission input torque command value and a speed ratio command value for matching the target acceleration and outputting a target acceleration value. Model means, first integration means for integrating a deviation between the acceleration command value and the acceleration estimation value, and second integration means for integrating a deviation between a target rotation speed of the continuously variable transmission input shaft and a rotation speed detection value. Control means having integration means; state feedback means for calculating the continuously variable transmission input torque command value and the speed ratio command value using outputs of the first and second integration means; And a state feedback gain is switched according to the slip state of the drive wheel, and when the drive wheel changes from the slip state to the non-slip state, the first and second integrating means are switched. An acceleration / deceleration control device for a vehicle including a continuously variable transmission, wherein an initial value is reset to zero. 3. The acceleration / deceleration control device for a vehicle equipped with a continuously variable transmission according to claim 1, wherein when the state feedback gain is switched, the integration means is configured to continuously change the operation amount before and after the switching. An acceleration / deceleration control device for a vehicle equipped with a continuously variable transmission, comprising an initial value setting means for setting an initial value of the vehicle. 4. The acceleration / deceleration control device for a vehicle equipped with a continuously variable transmission according to claim 2, wherein when the state feedback gain is switched, the first operation amount changes continuously before and after the switching. And an initial value setting means for setting an initial value of the second integrating means. 5. An acceleration / deceleration control device for a vehicle provided with a continuously variable transmission according to claim 1, wherein a state feedback gain is determined based on a vehicle speed detection value and an input torque of the continuously variable transmission. A vehicle acceleration / deceleration control device provided with a continuously variable transmission characterized by switching.