JPH09123794A - Automatic speed control device for vehicle - Google Patents

Abstract

(57) Abstract: Even if the throttle does not open before the maximum driving force is reached, an error is not accumulated in the running resistance estimation unit and the overshoot of the vehicle speed is surely prevented. According to the characteristics of the negative pressure type throttle actuator, the throttle may not be opened any more before reaching the throttle opening that realizes the maximum driving force of the vehicle. In such a case, the target driving force correction unit is provided. The final target driving force output by 26 is set to the target driving force before the difference between the target throttle opening TVOr and the actual throttle opening TVO exceeds a certain set value (for example, 5 °) by the target driving force limiter 29. By limiting, the target throttle opening TVOr is also limited to a certain limit value TVO / lt determined by the vehicle characteristics. This prevents the error of the throttle opening from accumulating inside the running resistance estimation unit 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic vehicle speed control device for automatically controlling the speed of a vehicle so that it runs at a constant target speed.

[0002]

2. Description of the Related Art Generally, an automatic vehicle speed control device attempts to keep a certain vehicle speed, for example, 80 km / h, on a road such as a highway which can travel a long distance at a constant speed. It is a function used for, by turning on the constant speed traveling set switch,
Unless the driver changes the vehicle speed by depressing the brake pedal or the accelerator pedal, the vehicle automatically adjusts the throttle opening by increasing or decreasing the vehicle speed while keeping the current speed and seeing the deviation between the actual vehicle speed and the target vehicle speed. A device for controlling acceleration / deceleration.

As a conventional example of such a vehicle automatic speed control device, there is a patent application filed by the applicant of the present application as Japanese Patent Application No. 7-20640. In the invention according to this prior application, a target driving force that matches the target vehicle speed and the actual vehicle speed is calculated based on the deviation between the target vehicle speed and the actual vehicle speed, and the throttle opening is controlled so that the actual driving force matches the target driving force. As a result, in the device for improving the vehicle speed control performance, since the driving force of the vehicle to be controlled is limited, when the driving force exceeding the driving force is required during the vehicle speed control, the target drive calculated in the device In order to prevent the force from exceeding the actual driving force, the target driving force is limited by using the driving force upper limit value calculated from the maximum engine torque, the engine rotation speed, and the reduction ratio of the speed reducer stored in advance. Even if you have the maximum driving force, the target driving force will not exceed the maximum driving force on the uphill where the driving force will be insufficient and the vehicle speed will decrease.
The error is not accumulated in the running resistance estimator to prevent the vehicle speed from overshooting when moving from an uphill to a flat road.

[0004]

However, in general, as shown in FIG. 9, in an actuator using an engine negative pressure as a drive source, the engine negative pressure decreases in reverse to the throttle opening operation, so that the maximum driving force TVO / The throttle may not open further (TVO / lt or more) before reaching pk, but in the above proposed device, the limiter does not operate normally in such a case, and calculation is performed inside the device. The target driving force that exceeds the actual driving force may continue to accumulate errors inside the running resistance estimator, and as a result, this effect remains for a while even after the road slope returns to a flat level. The vehicle speed VSP may still overshoot the target vehicle speed VSPr.

The present invention has been made in order to solve such a technical problem. Even if the throttle cannot be opened before the maximum driving force is reached, the target driving force and An automatic vehicle speed control device for a vehicle, which limits a target driving force so that a difference from an actual driving force does not occur, prevents an error from accumulating inside a running resistance estimating unit, and reliably prevents an overshoot of a vehicle speed. The purpose is to provide.

[0006]

According to a first aspect of the present invention, there is provided an automatic vehicle speed control device for a vehicle, the vehicle speed detecting means for detecting an actual vehicle speed of the vehicle, and a target vehicle speed for giving a target vehicle speed for traveling the vehicle at a constant vehicle speed. Setting means, throttle opening detecting means for detecting a throttle opening of the vehicle, and target driving force calculating means for calculating a target driving force necessary for matching the two based on the actual vehicle speed and the target vehicle speed. A running resistance estimating means for calculating a running resistance estimated value based on the actual vehicle speed and the target driving force; and a running resistance estimated value calculated by the running resistance estimating means for the target driving force computing means. A target driving force correction unit that corrects the calculated target driving force to calculate a final target driving force, and a slot that calculates a target throttle opening based on the final target driving force calculated by the target driving force correction unit. And a throttle opening control means for controlling the throttle opening to match the actual throttle opening with the target throttle opening, and a deviation between the actual throttle opening and the target throttle opening. And a target driving force limiting means for monitoring and changing the final target driving force to the final target driving force of one control cycle when the target throttle opening is larger than a preset value. Is.

In the vehicle automatic speed control device according to the first aspect of the present invention, the target driving force calculating means calculates the target driving force required to match the two based on the actual vehicle speed of the vehicle and the target vehicle speed, The running resistance estimation unit calculates a running resistance estimated value based on the actual vehicle speed and the calculated target driving force, and the target driving force correction unit corrects the target driving force based on the running resistance estimated value to finally determine the final value. Calculate the target driving force. Then, the throttle opening calculation means calculates the target throttle opening based on the final target driving force calculated by the target driving force correction means, and the throttle opening control means matches the actual throttle opening with this target throttle opening. The throttle opening is controlled so as to make it.

Here, the target driving force limiting means monitors the deviation between the actual throttle opening and the target throttle opening, and if the target throttle opening is larger than a preset value, the final target is opened. The driving force is changed to the final target driving force one control cycle before and is given to the throttle opening control means.

As a result, in the case where the engine negative pressure is lowered contrary to the throttle opening operation and the throttle cannot be opened before the maximum driving force is reached, the throttle is maintained at the maximum opening in the range in which it can be opened. However, by continuing the automatic speed control, the target driving force input to the running resistance estimation means is restricted so as not to exceed the actual driving force, and an error accumulates inside the running resistance estimation means, causing a flat road. Prevent the occurrence of a situation where the vehicle speed overshoots when moving.

According to a second aspect of the present invention, in the vehicle automatic speed control device according to the first aspect, the running resistance estimating means is a low-pass filter in which the target driving force is input, and robust compensation in which the actual vehicle speed is input. And an adder for obtaining the difference between the output of the low-pass filter and the output of the robust compensator.

In the vehicle automatic speed control device according to the second aspect of the present invention, the target resistance is input to the low-pass filter and the actual vehicle speed is input to the robust compensator in the running resistance estimating means, and the low-pass filter of these low-pass filters is operated. The difference between the output and the output of the robust compensator is calculated and used as the running resistance estimated value.

According to a third aspect of the present invention, in the vehicle automatic speed control device according to the first aspect, the vehicle resistance model in which the running resistance estimating means receives the target driving force as an input, the output of the vehicle characteristic model, and the An adder that calculates the difference from the actual vehicle speed,
And a robust compensator which receives the output of the adder as an input.

In the vehicle automatic speed control device according to the third aspect of the present invention, the running resistance estimating means obtains the difference between the output of the vehicle characteristic model having the target driving force as an input and the actual vehicle speed,
This difference value is input to the robust compensator to obtain the running resistance estimated value.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a hardware configuration of one embodiment of the present invention. A constant speed traveling control unit 1 is a microcomputer 1a including a CPU, a RAM, a ROM, various interfaces and various timers.
Is the main part, and executes the automatic speed control calculation according to the present invention in accordance with various programs to control the operation of various devices.

A main switch (MAIN_SW) as a power switch for the constant speed traveling control unit 1
And a constant speed traveling set switch (SET_SW) that commands the start of constant speed traveling control, an accelerator switch (ACC_SW) that gives an acceleration command for the current speed, and a coast switch (COAST_SW) that gives a deceleration command for the current speed. A switch group 2 including a cancel switch (CANCEL_SW) for canceling the constant speed traveling control and a brake switch (BRAKE_SW) for detecting that the brake pedal is depressed, and a vehicle speed sensor 3 using an electromagnetic pickup,
The throttle opening sensor 4 and the crank angle sensor 5 for measuring the engine rotation speed are connected as elements that provide input signals. A throttle actuator 6 is connected as a control target by the constant speed traveling control unit 1.

This throttle actuator 6 is of a negative pressure type and is equipped with a vacuum pump 7 driven by a motor, a vent valve 8 and a safety valve 9 which can communicate with the atmosphere, and drives the vacuum pump 7 with a motor and also has a vent valve. By controlling the opening degree of No. 8, the negative pressure is adjusted, and the opening degree of the throttle valve 10 is forcibly controlled to a desired value without depending on the accelerator operation. Further, the safety valve 9 is for opening to the atmosphere so that the control system does not drive the throttle when the automatic speed control mode is not set, and is controlled to be opened and closed by the constant speed traveling control unit 1.

The automatic speed control function executed by the constant speed running control unit 1 has the structure shown in FIG. 2. When the set switch is operated, the target vehicle speed VSPr is set so that the current speed VSP becomes the target vehicle speed VSPr and the vehicle runs at a constant speed. The target vehicle speed setting unit 21 for setting the vehicle speed, the vehicle speed detection unit 22 for detecting the current actual vehicle speed VSP based on the signal from the vehicle speed sensor 3, and the opening TV of the throttle valve 10 based on the signal from the throttle opening sensor 4.
The throttle opening detection unit 23 that detects O 2 is provided.

A target driving force calculation unit 24 for calculating a target driving force y4 based on a predetermined calculation method described later with respect to the target vehicle speed VSPr set by the target vehicle speed setting unit 21 and an actual vehicle speed.
Estimated running resistance x based on VSP and final target driving force y1
And a target driving force correction unit 26 that corrects the target driving force based on the target driving force y4 and the estimated running resistance value x to output the final target driving force y1. The throttle opening required to output the final target driving force y1 from the force correction unit 26, that is, the target throttle opening
A target throttle opening calculation unit 27 that calculates TVOr and a throttle opening control unit 28 that performs feedback control to match the actual throttle opening TVO with the target throttle opening TVOr.
It has.

As a feature of the present invention, the actual throttle opening TVO from the throttle opening detector 23 and the target throttle opening TVOr calculated by the target throttle opening calculator 27.
When the target throttle opening TVOr becomes larger than a predetermined value, for example, 5 °, the final target driving force y1 is limited to the final target driving force of one control cycle before, and the running resistance estimation unit 25 determines The target driving force limiting unit 29 is provided as the final target driving force of the control cycle.

Next, the automatic speed control process according to this embodiment will be described with reference to the flow charts of FIGS. The automatic speed control process is repeatedly executed at predetermined time intervals, for example, every 100 msec by a timer interrupt or the like. First, the vehicle speed sensor 3 and the throttle opening sensor 4
Then, the signals of the crank angle sensor 5 are read to calculate the average actual speed VSP, the average throttle actual opening TVO, and the average engine speed Ne during the control cycle of 100 msec (step P1).

In the automatic speed control mode so far, it is judged whether or not this automatic speed control mode has been canceled by the operation of the cancel switch this time (step P2). If the cancel switch is not turned on, then Next, it is judged whether the set switch of the automatic speed control mode is newly operated (step P
3).

If the set switch is newly operated in this control cycle, the average actual speed measured this time
Since the driver instructs the vehicle to run at a constant speed in VSP, set this actual speed VSP to the target speed VSPr (step P4), set the automatic speed control flag, and start automatic speed control from the next time. Prepare (step P5).

In the subsequent control cycles, the automatic speed control process is repeated until the cancel switch is operated or the brake is depressed to turn on the brake switch. That is, based on the actual vehicle speed VSP, the actual throttle opening TVO, and the engine speed Ne measured at the beginning of each control cycle in step P1, the target speed VSPr is changed to the actual speed VSPr.
The throttle opening degree control is performed so as to match (steps P1 to P3, P6 to P14).

When the automatic speed control is entered, steps P7 to P
11, the final target driving force y1 of the engine is calculated using the compensation calculation circuit 30 shown in FIG. 4, which uses the model matching method and the approximate zeroing method, which are widely known linear control methods.

The compensation calculation circuit 30 corresponds to a circuit for executing the calculation processing of the target driving force calculation unit 24, the running resistance estimation unit 25, the target driving force correction unit 26 and the target driving force limitation unit 29 in FIG. The matching compensator 31 corresponds to the target driving force calculator 24, the part including the low-pass filter 32, the robust compensator 33, and the adder 34 corresponds to the running resistance estimator 25, and the adder 35 corresponds to the target driving force corrector 26. The limiter 36 corresponds to the target power limiter 29.

Assuming that the transfer characteristic of the controlled object is the pulse transfer function P (z ⁻¹ ), the target driving force y1 is calculated and input to determine the vehicle speed.
The modeling of the controlled object that outputs VSP is an integral characteristic. In the compensation calculation circuit shown in FIG. 4, the transfer characteristic at this time can be set as the pulse transfer function P (z ^-1 ).

In the compensation calculation circuit of FIG. 4, z is a delay operator, which is multiplied by z ^-1 to obtain a value one control cycle before. Further, C1 (z ⁻¹ ) and C2 (z ⁻¹ ) execute disturbance estimation calculation by the approximate zeroing method and suppress the influence of disturbance and modeling error. Here, the running resistance estimation unit 25 is configured. ing. Further, C3 (z ⁻¹ ) of the model matching compensating unit 31 executes the compensation calculation by the model matching method, and the characteristic of the reference model H (z ⁻¹ ) having the first-order delay and the dead time which are the response characteristics of the controlled object determined in advance. To match.

When the target driving force y1 is input and the actual vehicle speed VSP is output, the P (z ^-1 ) is the integral element P1 (z ^-1 ) and the dead time shown in the following equation ( ¹ ). Element P2 (z ^-1 ) =
It can be ^{expressed by} the formula of z ^-2 .

[0029]

(Equation 1) Here, T: control cycle (here set to 100 msec) M: average vehicle weight At this time, C1 (z ^-1 ) and C2 (z ^-1 ) are expressed by the following equations 2 and 3 Become.

[0030]

(Equation 2) (Low-pass filter with time constant Tb)

(Equation 3) However, γ = exp (-T / Tb) Here, the compensator C2 is a robust compensator in which an inverse system of the vehicle characteristic model is low-pass filtered and outputs a driving force y3 corresponding to the actual vehicle speed VSP. Therefore, the running resistance estimation unit 25 in FIGS. 2 and 4 has the functional configuration shown in FIG. 5, and the robust compensator 33 in which the output of the low-pass filter 32 is low-pass filtered in the inverse system of the vehicle characteristic in the adder 34.
The running resistance estimated value x is obtained by subtracting the running resistance estimated value x from the output of the
Give to.

When the reference model H (z ^-1 ) is a first-order low-pass filter with a time constant Ta, ignoring the dead time of the controlled object, C3 of the model matching compensator 31 becomes a constant of the following equation 4. .

[0032]

(Equation 4) Based on the above control method, in step P7 in the flowchart of FIG. 3, the following equation 5 corresponding to the model matching compensation unit 31 is calculated to obtain the target driving force y4.
However, the data y (k-1) indicates the data of the (k-1) control cycle immediately before the k control cycle.

[0033]

## EQU00005 ## y4 (k) = K.multidot. (VSP r (k) -VSP (k)) At the next step P8, C2 (z- ¹ ) of the robust compensator 33 which is a part of the running resistance estimation unit 25. The following number 6 corresponding to
Performs expression calculations.

[0034]

(Equation 6) Next, the calculation of the following formula 7 for correcting the target driving force by the estimated running resistance value x is executed to obtain the final target driving force y1 (step P9). Here, y2 (k-2) is two control cycles before y2 (k) obtained by the calculation corresponding to the low-pass filter unit C1 (z- ¹ ) in step P11 described later, that is, (k-2
) Shows the data obtained in the control cycle. The calculation in step P11 corresponds to the integral element P1 (z ^-1 ) described above, and the dead time element P2 (z ^-1 ) = z ^-2 when the data of two control cycles before is used.

[0035]

[Formula 7] y1 (k) = y4 (k) + (y2 (k-2) -y3 (k)) where y2 (k-2) is a drive that is not affected by the running resistance found in the compensator. Although it is the force, y3 (k) is the value obtained by subtracting the running resistance from the driving force, so the expression y2 (k-2) -y3 (k) in the parentheses above is the running resistance estimated value. x.

An upper limit is applied to the final target driving force y1 (k) obtained in step P9. This calculation process is the process shown in the flowchart of FIG. 6, which is the process in the target driving force limiting unit 29 in FIG. 2 and in the limiter 36 corresponding to this in FIG.
The current target throttle opening TVOr is compared with the actual throttle opening TVO input from the throttle opening sensor 4 via the throttle opening detector 23 (step P101),
If the target throttle opening TVOr is larger than the actual throttle opening TVO by 5 ° or more, the final target driving force y1 (k)
Is one control cycle before, that is, y1 (k-1) is y5
By setting to (k), the target throttle opening is limited (step P102).

After performing the upper limit value limiting process of the target driving force in this way, the calculation of the following formula 8 corresponding to the compensator C1 (z ^-1 ) as the low pass filter which is a part of the running resistance estimation process is executed. (Step P11).

[0038]

Y2 (k) = γ · y2 (k-1) + (1-γ) · y5 (k-1) In the subsequent step P12, the target throttle opening degree calculation unit 2
A target throttle opening degree calculation corresponding to the processing of 7 is executed. For this purpose, the target engine torque is calculated from the final target driving force y1 (k), and the target throttle opening TVOr is calculated by table calculation from the target engine torque using the engine non-linear characteristic data map registered in advance.

Then, the throttle opening control unit 28 sets the actual throttle opening TVO against the target throttle opening TVOr.
Control to match. That is, the target throttle opening
The PWM control of the vacuum pump 7 and the vent valve 8 of the negative pressure type throttle actuator 6 is performed based on the deviation between TVOr and the actual throttle opening TVO (steps P13 and P14).

If the cancel switch is operated during automatic speed control (step P2), the automatic speed control flag is cleared, all parameters are returned to the initial state, and automatic speed control is stopped (step P15, P16).

As described above, in the vehicle automatic speed control system according to this embodiment, the target driving force is subjected to the upper limit limiting process, so that the engine negative pressure is reduced to reach the maximum driving force, contrary to the throttle opening operation. When the throttle cannot be opened before, it is prevented to further control the target throttle opening TVOr to realize the final target driving force y1 (k). In other words, as shown in FIG. 7, when the vehicle goes uphill while executing the automatic speed control for constant speed running, the throttle is increased to increase the target driving force in order to maintain the vehicle speed VSP at the target vehicle speed VSPr. The opening is controlled to open, but due to the characteristics of the negative pressure type throttle actuator, the throttle may not open any further before reaching the throttle opening that realizes the maximum driving force of the vehicle.In such a case, The final target driving force output from the compensation calculation processing circuit 30 is opened over a set value (here, set to 5 °) having a difference between the target throttle opening TVOr and the actual throttle opening TVO. By limiting to the previous target driving force, the target throttle opening TVOr is also limited to a certain limit value TVO / lt which is determined by the vehicle characteristics. This prevents the difference in throttle opening from accumulating, avoids overshooting the vehicle speed for a while when entering a flat road, and enables speed control that matches the original target vehicle speed VSPr at an early stage. become. In addition, in the case of this embodiment, even if there are slight individual differences in vehicle characteristics between vehicles, it is possible to limit the throttle opening to the limit value TVO / lt or less corresponding to each vehicle.

The comparison reference value for limiting the upper limit value of the throttle opening is set to 5 ° in the above embodiment, but it may be set to a value larger or smaller than that.

In the above embodiment, the functional configuration of the running resistance estimating unit 25 is as shown in FIGS. 4 and 5, but it can be changed as shown in FIG. That is, in the adder 41, the output of the vehicle characteristic model 42 having the final target driving force y1 as an input is subtracted from the actual vehicle speed VSP, and this is input to the robust compensator 43 configured by the inverse system of the vehicle characteristic and the low-pass filter. However, the output of the robust compensator 43 may be used as the running resistance estimated value x.

[0044]

As described above, according to the present invention, the target driving force required to match the actual vehicle speed and the target vehicle speed of the vehicle is calculated, and the actual vehicle speed and the calculated target drive speed are calculated. The driving resistance estimated value is calculated based on the driving force, the target driving force is corrected based on the driving resistance estimated value to calculate the final target driving force, and the target throttle opening is calculated based on the final target driving force. However, when the automatic speed control is performed by controlling the throttle opening so that the actual throttle opening matches the target throttle opening, the target driving force limiting means sets the deviation between the actual throttle opening and the target throttle opening. When the target throttle opening becomes larger than the preset reference value, the final target driving force is changed to the final target driving force one control cycle before,
Since the throttle opening control is performed based on this, open the throttle when the engine negative pressure decreases and the throttle cannot be opened before reaching the maximum driving force, contrary to the throttle opening operation. By continuing the automatic speed control while maintaining an almost maximum opening within the range where it is possible to limit, it is possible to limit the target driving force input to the running resistance estimation means so as not to exceed the actual driving force,
If an error accumulates inside the running resistance estimation means and the vehicle speed overshoots when the vehicle moves from an uphill to a flat road, it can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a hardware configuration of one embodiment of the present invention.

FIG. 2 is a functional block diagram of automatic speed control executed by a microcomputer in the above embodiment.

FIG. 3 is a flowchart of automatic speed control executed by a microcomputer in the above embodiment.

FIG. 4 is a block diagram of automatic speed control executed by a microcomputer in the above embodiment.

FIG. 5 is a functional block diagram of a running resistance estimation unit in the above embodiment.

FIG. 6 is a flowchart of a target driving force upper limit limiting process in the automatic speed control executed by the microcomputer in the above embodiment.

FIG. 7 is a timing chart showing an automatic speed control characteristic according to the above embodiment.

FIG. 8 is a functional block diagram showing another functional configuration example of the traveling resistance estimation unit in the above embodiment.

FIG. 9 is a timing chart showing an automatic speed control characteristic of a conventional example.

[Explanation of symbols]

 1 control unit 1a microcomputer 2 switch group 3 vehicle speed sensor 4 throttle opening sensor 5 crank angle sensor 6 throttle actuator 7 vacuum pump 8 vent valve 9 safety valve 10 throttle valve 21 target vehicle speed setting part 22 vehicle speed detecting part 23 throttle opening detection Part 24 Target driving force calculation unit 25 Running resistance estimation unit 26 Target driving force correction unit 27 Target throttle opening calculation unit 28 Throttle opening control unit 30 Compensation calculation circuit 31 Model matching compensation unit 32 Low-pass filter 33 Robust compensator 34 Adder 35 Adder 36 Limiter 41 Adder 42 Vehicle Characteristic Model 43 Robust Compensator 43

Claims (3)

[Claims] 1. A vehicle speed detecting means for detecting an actual vehicle speed of a vehicle, a target vehicle speed setting means for giving a target vehicle speed for causing the vehicle to travel at a constant vehicle speed, and a throttle opening detecting means for detecting an opening degree of a throttle of the vehicle. A target driving force calculating means for calculating a target driving force required to match the two based on the actual vehicle speed and the target vehicle speed; and a running resistance estimated value based on the actual vehicle speed and the target driving force. And a target drive for calculating a final target drive force by correcting the target drive force calculated by the target drive force calculation unit based on the drive resistance estimated value calculated by the drive resistance estimation unit. Force correction means, throttle opening calculation means for calculating a target throttle opening based on the final target driving force calculated by the target driving force correction means, and the actual throttle opening calculated by the target throttle opening. The throttle opening control means for controlling the throttle opening to match the throttle opening, and the deviation between the actual throttle opening and the target throttle opening are monitored, and the target throttle opening is set in advance. If the value exceeds the value, the final target driving force is set to 1
An automatic speed control device for a vehicle, comprising: target drive force limiting means for changing to a final target drive force before a control cycle. 2. The running resistance estimating means includes a low-pass filter having the target driving force as an input, a robust compensator having the actual vehicle speed as an input, an output of the low-pass filter and an output of the robust compensator. The automatic speed control device for a vehicle according to claim 1, wherein the automatic speed control device is constituted by an adder for obtaining a difference. 3. The running resistance estimating means outputs a vehicle characteristic model with the target driving force as an input, an adder for obtaining a difference between the output of the vehicle characteristic model and the actual vehicle speed, and an output of the adder. The vehicle automatic speed control device according to claim 1, wherein the automatic speed control device comprises a robust compensator as an input.