JPH06247183A - Vehicle speed control device - Google Patents

Abstract

PURPOSE:To provide a vehicle speed control device which determines a safe target distance between cars from a vehicle running a head in proportion to detected load, and can properly maintain the distance between cars at all times when a vehicle is in a follow-up running by controlling vehicle speed based on the difference between the aforesaid target distance and an actual distance between cars. CONSTITUTION:The device is made up of a distance between cars detecting means 1 for a vehicle running ahead, a vehicle speed detecting means 2 for his own vehicle, speed control start and release means 3 and 4, a target vehicle speed setting means 5 with a display unit, and of a load detecting means 10 measuring the spring weight of his own vehicle. The device is also made up of a controller 6 equipped with a CPU, ROM, RAM and I/O for reading, storing and operation processing, a throttle operating means 7, a gear position operating means 8, and of a brake operating means 9. A target vehicle speed is set up in accordance with a set program, a target distance between cars is determined based on the present weight of his own car, an actual distance between cars is compared with the target distance between cars, the change component of vehicle speed at present is determined, and the manipulated variables of the throttle and the brake, and the optimum gear position are determined, so that the vehicle copes with the situation for these.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control device, and more particularly to a vehicle speed control device having an inter-vehicle distance control (following traveling control) function.

[0002]

2. Description of the Related Art In order to improve easy driveability,
Recently, the number of vehicles equipped with a speed control device that performs a constant speed traveling (auto-cruise) function to control the vehicle to travel at a constant speed has been increasing recently. In this speed control device, the driver operates the accelerator pedal. Without doing so, the engine output is controlled by adjusting the throttle opening etc. so that the speed of the host vehicle can be kept constant.

However, with this speed control device, there is a risk of a rear-end collision when the vehicle ahead is slower than the host vehicle. Therefore, recently, a device has been developed which detects the inter-vehicle distance to a vehicle ahead and maintains a predetermined safe inter-vehicle distance.

The prior art disclosed in Japanese Patent Laid-Open No. 55-86000, which is an example of such a method, calculates a safe inter-vehicle distance according to a vehicle speed, and opens a throttle when a preceding vehicle does not exist within the safe inter-vehicle distance. The vehicle speed is controlled by adjusting the vehicle speed to a target value at a set vehicle speed, and if it exists, the follow-up driving control is performed by decreasing the throttle opening so that a safe inter-vehicle distance is achieved.

[0005]

By the way, in the above-mentioned prior art and the like, when the host vehicle is controlled to travel at a constant inter-vehicle distance from the vehicle in front, the load capacity of the vehicle such as a truck is large. Because the brake is hard to work,
The target inter-vehicle distance is usually set to a large value so as not to collide with a vehicle ahead.

[0006] Therefore, there is a problem in that the vehicle-to-vehicle distance becomes unnecessarily large for an empty vehicle and the road utilization efficiency decreases.

Therefore, in order to remedy the above-mentioned problems, the present invention performs constant speed traveling control targeting a set vehicle speed when there is no preceding vehicle within the safe inter-vehicle distance, and when there is a safe inter-vehicle distance. An object of the present invention is to enable control in consideration of the load of a vehicle in a speed control device for a vehicle that performs follow-up traveling control so that the distance becomes a distance.

[0008]

In order to achieve the above object, a vehicle speed control device according to the present invention includes a means for detecting an actual inter-vehicle distance from a vehicle ahead, an actual vehicle speed detecting means, and a target vehicle speed setting. Means, vehicle speed control means, operation start detection means, operation release detection means, load detection means, and target vehicle distance proportional to the detected load while the operation start detection means detects the operation start. If the target inter-vehicle distance is greater than the actual inter-vehicle distance, the vehicle speed change amount is determined based on the difference between the inter-vehicle distances, and if the target inter-vehicle distance is less than the actual inter-vehicle distance, the difference between the target vehicle speed and the actual vehicle speed. And a controller for controlling the vehicle speed control means by obtaining a vehicle speed change amount based on the above.

Further, in the present invention, the target vehicle speed may be preset in the controller without using the setting means.

[0010]

In the vehicle speed control device according to the present invention,
The controller obtains a target inter-vehicle distance until the operation start detecting means detects the operation start and the operation release detecting means releases the operation.

The target inter-vehicle distance is obtained by the controller as a value proportional to the load detected by the load detecting means. When the load is large (when the vehicle load capacity is large), the target inter-vehicle distance is increased, and vice versa. When the load is small, the target inter-vehicle distance is set to be small.

Then, the target inter-vehicle distance is compared with the actual inter-vehicle distance detected by the means for detecting the actual inter-vehicle distance to the preceding vehicle.

As a result of this comparison, when the target inter-vehicle distance> the actual inter-vehicle distance, the vehicle speed change amount is obtained based on the difference between the two inter-vehicle distances (target inter-vehicle distance-actual inter-vehicle distance).

On the contrary, when the target inter-vehicle distance <the actual inter-vehicle distance, the difference between the two inter-vehicle distances becomes negative and the above control cannot be applied. In this case, the target vehicle speed of the vehicle is set by the means. The vehicle speed change amount is obtained based on the difference between the target vehicle speed (or the target vehicle speed stored in the controller itself) and the actual vehicle speed (target vehicle speed> actual vehicle speed at this time).

Since the vehicle speed control means is controlled by the calculated vehicle speed change amount, the vehicle speed is decelerated so as to reach the target inter-vehicle distance when the preceding vehicle is short, and the target vehicle speed is kept constant when the preceding vehicle is far from the target inter-vehicle distance. Acceleration / deceleration is performed so that high speed traveling is performed.

Although the following / constant speed running is performed in this way, the inter-vehicle distance is proportional to the load detected by the load detecting means. Therefore, when the vehicle load is large, the inter-vehicle distance can be made large and the vehicle speed can be decelerated quickly. As well as
Since the target inter-vehicle distance becomes small when the vehicle load is small such as when the vehicle is empty, it is not necessary to set the inter-vehicle distance more than necessary.

When deceleration is performed when the vehicle is empty, the change in vehicle speed obtained based on the difference between the target inter-vehicle distance and the actual inter-vehicle distance is also small, so that a slow braking effect is obtained and speed hunting is performed. (Deceleration shock) can be reduced, and therefore the riding comfort is improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a vehicle speed control device according to the present invention. Each block will be described in sequence.

1: Vehicle-to-vehicle distance detecting means for detecting the vehicle-to-vehicle distance to the vehicle in front, which is composed of, for example, an FM-CW radar, a laser radar, an ultrasonic sensor or the like.

2: Vehicle speed detecting means This is composed of a sensor for detecting the traveling speed of the own vehicle, and usually a reed switch or the like is used.

3: Actuation start detecting means Normally, it is constituted by a digital switch (push switch etc.), and this switch is turned off by the operation of the driver.
The speed control of the present invention is started when it is detected that the state has changed to the ON state.

4: Operation release detecting means This is to detect the case where the driver operates the brake pedal, the shift lever, or a predetermined switch to release the speed control of the present invention.

5: Target vehicle speed setting means It is composed of a volume (knob), a rotary switch or the like so that the driver can set an arbitrary value, and the number can be adjusted by a mechanism for adjusting the time of the clock. Anything is fine. It may also include a display unit for notifying the driver of the set value. When the target vehicle speed is set in the controller, which will be described later, this means 5 may be omitted.

6: Controller An input port 61 for reading the input signals from the above-mentioned respective means 1 to 5, the programs of FIGS. 2 and 3 and fixed control parameters, etc. are stored in advance and also shown in FIGS. 5 (a) and 5 (b). R) in which the shift map for the automatic transmission shown in FIG.
An OM 62, a RAM 63 for temporarily storing input signals and variable control parameters, a CPU 64 for performing arithmetic processing based on the program, and an output port 65 for sending output signals to each operation means described later. Control means.

7: Throttle operating means Normally, it is composed of a motor, a valve, etc., and operates the throttle position of the engine (not shown) based on the output signal from the controller 6.

8: Gear position operating means For operating the gear position (including overdrive) of the automatic transmission on the basis of the output signal from the controller 6, which is well known in accordance with the structure of the automatic transmission of an automatic vehicle. Good.

9: Brake operating means Normally, it is composed of a hydraulic valve or the like, and operates the deceleration force (brake force) based on the output signal from the controller 6.

10: Load Detecting Means A sensor for measuring the sprung weight of the vehicle, particularly for measuring the loaded weight of a vehicle such as a truck.

The throttle operating means 7, the gear position operating means 8 and the brake operating means 9 constitute a vehicle speed control means.

The operation of the above embodiment will be described below with reference to the flow charts of the control programs shown in FIGS. These control programs are executed by the controller 6
It is stored in the internal ROM 62 and is executed by the CPU 64 at a predetermined constant cycle. Also, the CPU 64
It is assumed that a setting flag described later is turned off when is initialized by turning on an ignition key (not shown).

Control program in FIG . 2 Step 21: Judge the state of the setting flag indicating whether or not speed control is being executed, and if ON, proceed to Step 24, OF
If F (when the ignition key is ON), step 22
Go to.

Step 22: If the operation start detecting means (set switch) 3 is turned on by the driver's operation, the process proceeds to step 23, and if it is off (not operated), the process proceeds to step 26.

Step 23: Set the setting flag to ON and proceed to step 24.

Step 24: The operation release detecting means 4 detects whether or not the driver is performing a predetermined speed control release operation (stepping on the brake pedal, changing the shift lever position, etc.), and is performing the release operation (YES). If so, the process proceeds to step 25, and if not operated (NO), the process proceeds to the speed control subroutine of step 30 (see FIG. 3).

Step 25: Turn off the setting flag and proceed to step 26.

Step 26: Release the speed control shown in FIG.
The throttle opening, braking force, and gear position are determined according to the driving operation of the driver. Incidentally, as the shift map of the automatic transmission at this time, a normal shift map as shown in FIG. 5 (a) is used.

The subroutine of FIG . 3 (step 30 of FIG. 2)
Details of Step ) Step 31: Target Vehicle Speed Vt by Target Vehicle Speed Setting Means 5
Read. At this time, the target vehicle speed Vt may be set not in the target vehicle speed setting means 5 but in a preset value in the ROM 62 of the controller 6 (for example, 100 km / h which is the speed limit of general highways).

Step 32: The current inter-vehicle distance D is read by the inter-vehicle distance detecting means 1.

Step 33: The current vehicle speed V is read by the vehicle speed detecting means 2.

Step 34: The inter-vehicle distance estimated to be appropriate for the current load W is calculated, and this value is set as the target inter-vehicle distance Dt.

A method of calculating the target inter-vehicle distance Dt is shown in FIG. 4, which will be described below.

First, the CPU 64 reads the current load W (kg) of the vehicle by the load detecting means 10. At this time, 10
It is assumed that the individual load sample values W1, W2, ..., W10 are continuously read at a constant cycle (step 4 in FIG. 4).
1).

The load sample values W1, W2, ..., W10 thus read are averaged to obtain the average load W _A (step 42).

Further, based on this average load W _A , the target inter-vehicle distance Dt is calculated by the following formula (step 43). Dt = Do + k · W _A

In the above equation, Do is a constant target inter-vehicle distance (m) that is optimal in the case of an empty vehicle, and it can be set in advance when the speed control device is mounted on the vehicle. Further, k is a constant expressed in the unit of m / kg, and the optimum value may be obtained by an experiment.

The target inter-vehicle distance Dt is equal to the load W.
The values for may be stored in the ROM 62 as a table.

Step 35: The current inter-vehicle distance D is compared with the target inter-vehicle distance Dt, and if Dt ≧ D (that is, if there is a dangerous situation in which the preceding vehicle exists within the range of the target inter-vehicle distance Dt), the inter-vehicle distance. In order to control D to the value of the target inter-vehicle distance Dt, the routine proceeds to step 36. On the contrary, if Dt <D (that is, if there is no preceding vehicle within the range of the target inter-vehicle distance Dt), the vehicle speed V is set to the target vehicle speed. The process proceeds to step 37 to control the value of Vt.

Step 36: How much to accelerate or decelerate the current vehicle speed V, that is, the current vehicle speed V
Change (acceleration / deceleration) ΔV is calculated. The value of this variation ΔV can be obtained based on the value of (Dt−D) which is the difference between the target inter-vehicle distance Dt and the current inter-vehicle distance D. For example, it can be obtained by a linear expression such as ΔV = X * (Dt−D) + Y (X and Y are constants).

In this case, the preceding vehicle is approaching and is dangerous, so it is necessary to decelerate, and the constants X and Y are set so that ΔV becomes a negative value.

Step 37: Similar to step 36, the change amount ΔV of the current vehicle speed V is obtained. This step 3
It was found from 5 that the vehicle ahead was not approaching and the vehicle was in a safe inter-vehicle distance. Therefore, it is necessary to perform constant speed traveling at the target vehicle speed Vt.

For this reason, since the equation of step 36 cannot be used as it is, the value of the variation ΔV is obtained based on the value of (Vt-V) which is the difference between the target vehicle speed Vt and the current vehicle speed V. To do. For example, ΔV = α * (Vt−V) + β
(Α and β are constants).

In this case, it is uncertain whether Vt-V or not. When Vt> V, the target vehicle speed has not been reached, so it is necessary to accelerate. Therefore, ΔV must be an acceleration such that ΔV> 0, and both constants α and β are positive values.

On the contrary, when Vt <V, the target vehicle speed is exceeded, so it is necessary to decelerate, and ΔV must be a deceleration such that ΔV <0. Therefore, both constants α and β are also positive values.

Although only a simple example is shown for calculating the change ΔV in steps 36 and 37, the current vehicle speed V is known as known in the prior art.
It goes without saying that the value of ΔV may be appropriately changed in accordance with the current inter-vehicle distance D, the time variation of the inter-vehicle distance D (that is, the vehicle speed relative to the preceding vehicle), or the like.

Step 38: The throttle operation amount, the brake operation amount, and the optimum gear position in the automatic transmission are obtained based on the value of the change ΔV obtained in step 36 or step 37.

FIG. 5 shows an example of the relationship between the variation ΔV and the throttle variation Δθ, and the variation ΔV and the braking force variation ΔP. Here, a constant Vc that takes a negative value is defined, and if ΔV ≧ Vc means acceleration or small deceleration, the throttle opening operation (Δθ) is used without braking.

On the contrary, when ΔV <Vc, a large deceleration is shown, so the throttle is fully closed and the braking force is operated (ΔP).

In FIG. 5, ΔV and Δθ, and ΔV and ΔP are shown as straight lines in a simplified manner, but of course they may be curves obtained from vehicle specifications and running resistance.

The optimum gear position in the automatic transmission is determined by the above-mentioned throttle opening and vehicle speed V by a known shift map (not shown).

[0060]

As described above, according to the vehicle speed control device of the present invention, the target inter-vehicle distance is obtained in proportion to the detected load, and when the target inter-vehicle distance is larger than the actual inter-vehicle distance, the inter-vehicle distance is increased. The vehicle speed change amount is obtained based on the difference in distance, and when the target inter-vehicle distance is smaller than the actual vehicle distance, the vehicle speed control means is controlled by obtaining the vehicle speed change amount based on the difference between the target vehicle speed and the actual vehicle speed. With this configuration, when the vehicle load is large, the inter-vehicle distance can be set to a large value so that the vehicle can be decelerated earlier, and when the vehicle load is low when the vehicle is empty, the target inter-vehicle distance becomes smaller. It is possible to improve the efficiency of road use because there is no need to put.

Further, when deceleration is performed when the vehicle is empty, abrupt braking operation can be avoided and speed hunting (deceleration shock) can be reduced.
The riding comfort is also improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle speed control device according to the present invention.

FIG. 2 is a flowchart of a control program executed by a controller used in the vehicle speed control device according to the present invention.

FIG. 3 is a flowchart of a control program for executing a “execution of speed control” subroutine in FIG.

FIG. 4 is a flowchart of a control program for executing a subroutine of “calculation of target inter-vehicle distance” in FIG.

FIG. 5 is a graph diagram for explaining an operation of a throttle opening degree and an operation of a braking force corresponding to a vehicle speed change amount in the present invention.

[Explanation of symbols]

 1 inter-vehicle distance detecting means 2 vehicle speed detecting means 3 operation start detecting means 4 operation releasing detecting means 5 target vehicle speed setting means 6 controller 7 throttle operating means 8 gear position operating means 9 brake operating means 10 load detecting means Or, shows a considerable portion.

Claims (2)

[Claims] 1. A means for detecting an actual vehicle-to-vehicle distance from a preceding vehicle, an actual vehicle speed detecting means, a target vehicle speed setting means, a vehicle speed control means, an operation start detecting means, an operation release detecting means, and a load detecting means. While the operation start detecting means is detecting the start of operation, a target inter-vehicle distance proportional to the detected load is obtained, and when the target inter-vehicle distance is larger than the actual inter-vehicle distance, based on the difference between the two inter-vehicle distances. And a controller that controls the vehicle speed control means by determining the vehicle speed change amount based on the difference between the target vehicle speed and the actual vehicle speed when the target vehicle distance is smaller than the actual vehicle distance. A vehicle speed control device characterized by the above. 2. The vehicle speed control device according to claim 1, wherein the target vehicle speed is preset in the controller without using the setting means.