JPH11151952A - Control device for preceding vehicle following-up - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the shift hunting in a downhill road for enabling shifting down or up to meet the operational feeling of occupants by estimating the grade of a road surface, and when the estimated value of the grade of the road surface in a downhill road is larger than a prescribed value, prohibiting shift-up. SOLUTION: Laser beams are sweepingly emitted and the time until the reflected beams of a preceding vehicle are received is measured by an inter-vehicle distance sensor 1, and the inter-vehicle distance is calculated by a distance-measuring signal processor 11. The period of the vehicle speed from a vehicle speed sensor is measured by vehicle speed signal processor 21 for detecting the speed of own vehicle. On the basis of the inter-vehicle distance and the own vehicle speed, a target inter-vehicle distance and a target own vehicle speed are calculated, and a relative speed calculating part 501 calculates the relative speed with regard to the preceding vehicle by the calculated inter-vehicle distance. Considering relative speed, an inter-vehicle distance control part 502 calculates the inter-vehicle distance so as to coincide with the target. A vehicle speed control part 51 consisting of a throttle servo part 512, a vehicle speed servo part 511, and a shift control part 513 controls the valve opening, change gear ratio, and braking force so as to obtain a target vehicle speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preceding vehicle follow-up control device that recognizes a preceding vehicle and follows the preceding vehicle while maintaining a constant inter-vehicle distance.

[0002]

2. Description of the Related Art A preceding vehicle following control in which a shift down condition and a shift up condition of a transmission are set according to each of a flat road, an uphill road and a downhill road so that an appropriate inter-vehicle distance is always maintained. An apparatus is known (for example, see Japanese Patent Application Laid-Open No. 7-223457).

However, in the conventional preceding vehicle following control device described above, when the vehicle is following on a downhill road, if the vehicle approaches the preceding vehicle due to a brake operation of the preceding vehicle, a downshift, a difference in engine braking force, etc., the following distance is obtained. When the vehicle is decelerated by the downshift and the inter-vehicle distance with the preceding vehicle is increased, the upshift is satisfied by satisfying the upshift condition. Shifting up shifts down again by approaching the preceding vehicle, and downshifting increases the inter-vehicle distance and shifts up again. On a downhill road, there is a problem that shift hunting that repeats such an operation occurs and gives an occupant a feeling of discomfort.

An object of the present invention is to prevent shift hunting on a downhill road.

[0005]

According to a first aspect of the present invention, there is provided an inter-vehicle distance detecting means for detecting an inter-vehicle distance from a preceding vehicle, and a target vehicle speed for matching a detected inter-vehicle distance to a target inter-vehicle distance. Inter-vehicle distance control means for calculating, own-vehicle speed detecting means for detecting own-vehicle speed, and vehicle speed control means for calculating target braking / driving force for matching the own-vehicle speed detection value to the target vehicle speed;
Drive control means for controlling the driving of the prime mover, transmission and braking device in accordance with the target braking / driving force, road surface gradient estimating means for estimating the road surface gradient, and shifting up when the road surface gradient estimated value on a downhill road is equal to or more than a predetermined value And shift-up prohibiting means for prohibiting the operation. (2) The preceding vehicle following control device according to claim 2, wherein the vehicle speed control means includes disturbance compensation means for estimating a disturbance applied to the vehicle at the time of traveling and compensating a driving force of the vehicle based on the disturbance estimation value. The road surface gradient is estimated by the means based on the disturbance estimation value estimated by the disturbance compensation means. (3) The preceding vehicle follow-up control device according to claim 3 is configured to provide a hysteresis to the predetermined value serving as a criterion for judging shift-up inhibition.

[0006]

(1) According to the first aspect of the invention, the gradient of the road surface is estimated, and when the estimated value of the road surface gradient on the downhill road is equal to or more than the predetermined value, the shift-up is prohibited. Can prevent shift hunting, etc.
Shift down and shift up can be performed according to the driver's driving sensation. (2) According to the invention of claim 2, since the road surface gradient is estimated based on the disturbance estimated value estimated by the disturbance compensating means of the vehicle speed control, the road surface gradient is estimated without using a special sensor. can do. (3) According to the third aspect of the present invention, the predetermined value serving as the criterion of the shift-up prohibition is provided with the hysteresis, so that shift hunting can be more reliably prevented.

[0007]

FIG. 1 is a diagram showing the configuration of an embodiment. The inter-vehicle distance sensor 1 is a radar-type sensor that sweeps laser light and receives reflected light from a preceding vehicle. The inter-vehicle distance may be measured using radio waves or ultrasonic waves. The vehicle speed sensor 2 is attached to the output shaft of the transmission, and outputs a pulse train having a cycle according to the rotation speed. The throttle actuator 3 opens and closes the throttle valve in accordance with the throttle valve opening signal, and adjusts the engine output by changing the amount of air taken into the engine.
The automatic transmission 4 changes the gear ratio according to the vehicle speed and the engine torque. In this embodiment, the overdrive (O
The following describes an example of a four-speed transmission with D). The braking device 6 is a device that generates a braking force on the vehicle.

The follow-up controller 5 includes a microcomputer and its peripheral parts, determines a target vehicle speed based on the detected distance between the vehicles and the detected vehicle speed, and controls the throttle actuator 3, the automatic transmission 4, and the braking device 6.
The follow-up controller 5 controls the control block 1 shown in FIG.
1, 21, 50 and 51 are constituted.

In FIG. 2, a distance measurement signal processing section 11 measures the time from when the laser beam is scanned by the inter-vehicle distance sensor 1 to when the reflected light of the preceding vehicle is received, and the inter-vehicle distance LT from the preceding vehicle is measured. Calculate. When there are a plurality of preceding vehicles ahead, the preceding vehicle to be followed is specified and the inter-vehicle distance LT is calculated. Since the method of selecting the preceding vehicle is already known, the description is omitted. The vehicle speed signal processing unit 21 measures the cycle of the vehicle speed pulse from the vehicle speed sensor 2 and detects the speed VS of the host vehicle.

The preceding vehicle following control unit 50 includes a relative speed calculation unit 501, an inter-vehicle distance control unit 502, and a target inter-vehicle distance setting unit 503. Based on the inter-vehicle distance LT and the own vehicle speed VS, the target inter-vehicle distance LT * Calculate the vehicle speed V *. The relative speed calculation unit 501 calculates a relative speed ΔV with respect to the preceding vehicle based on the inter-vehicle distance LT detected by the distance measurement signal processing unit 11. The inter-vehicle distance control unit 502 calculates a target vehicle speed V * for matching the inter-vehicle distance LT with the target inter-vehicle distance LT * in consideration of the relative speed ΔV. Target inter-vehicle distance setting unit 503
Sets the target inter-vehicle distance LT * according to the vehicle speed VT of the preceding vehicle or the own vehicle speed VS.

The vehicle speed control unit 51 includes a vehicle speed servo unit 5
11, throttle servo unit 512 and shift control unit 5
13, the throttle valve opening of the throttle actuator 3 so that the own vehicle speed VS becomes the target vehicle speed V *,
The gear ratio of the automatic transmission 4 and the braking force of the braking device 6 are controlled. The vehicle speed servo unit 511 calculates a throttle valve opening command value for matching the own vehicle speed VS to the target vehicle speed V * and a margin of the deceleration force of the vehicle. The deceleration force margin will be described later. In this embodiment, a vehicle speed servo system is designed using a robust model matching control technique. The throttle servo unit 512 controls the drive of the throttle actuator 3 according to the throttle valve opening command value. The shift control unit 513 calculates the margin of the deceleration force and the relative speed Δ
V to determine whether to execute shift up / down,
Drive control of the automatic transmission 4 is performed.

FIG. 3 shows a configuration of a vehicle speed servo system based on a robust model matching control method. The vehicle speed servo system according to this embodiment includes a robust compensator, a model matching compensator, and a deceleration force margin calculation unit. The vehicle to be controlled is represented by a mathematical model Gv (s) using the target driving force as an operation amount and the vehicle speed as a control amount. Note that this transfer characteristic Gv
(s) does not include a time delay element that is a power train delay.

[0013] The robust compensator estimates disturbance dv such as running resistance and running wind pressure. H (s) is a low-pass filter that performs low-pass filter processing on the target driving force For 'after the limiter processing. Although not shown, the current actual driving force is obtained by multiplying the target driving force For 'after the low-pass filter processing by a dead time element which is a delay in the power train of the vehicle. This driving force includes a driving force for disturbance such as running resistance in addition to a driving force for maintaining the vehicle speed VS. On the other hand, the compensator H (s) / Gv (s) is obtained by multiplying the inverse system of the vehicle model by a low-pass filter H (s). The compensator processes the own vehicle speed VS to obtain the current own vehicle speed VS. Find the driving force to maintain. The difference between these driving forces is a driving force for disturbance such as running resistance, that is, a disturbance estimation value dv ′.

The model matching compensator adjusts the own vehicle speed VS while making the response characteristic of the controlled object coincide with a predetermined characteristic.
Is set to the target vehicle speed V *. Then, the estimated disturbance value dv 'is added to the driving force command value For.
Is added to obtain the target driving force For '.

In this embodiment, the deceleration force margin is defined as a difference between a required deceleration force value and a maximum deceleration force corresponding to a target vehicle speed at the fourth speed (OD). The deceleration force margin calculation unit is designed to prevent frequent downshifts and shift hunting.
A low-pass filter process of, for example, about 0.5 Hz is performed on the target driving force For 'to determine a required deceleration force value. Also, 4
From the characteristics of the deceleration α with respect to the vehicle speed V when the throttle valve is fully closed at the speed (OD), the maximum deceleration corresponding to the target vehicle speed V * is calculated by lookup, further multiplied by the vehicle mass M, and the total reduction ratio is calculated. Divide by (4th gear ratio × final gear ratio) to find the maximum deceleration force at 4th speed. Then, the maximum deceleration force is subtracted from the required deceleration force value to obtain a deceleration force margin. The greater the deceleration margin, the lower the need for downshifting.
Conversely, the smaller the deceleration force margin, the higher the need for downshifting.

Next, a method of determining shift down and shift up will be described. In this embodiment, (relative speed)
≦ 0 (approach the preceding vehicle) and (deceleration margin) ≦
Shift down at SG1. Conversely, the shift-up is performed when (relative speed)> 0 (away from the preceding vehicle) and (deceleration force allowance) ≧ SG2. Note that SG
1, SG2 is a threshold value, and SG1 <SG2 in order to prevent shift hunting. SG2 is set to a small value so as to shift up before the throttle valve starts to open, that is, to shift up earlier, in order to suppress a shift shock at the time of shifting up.

Next, the hunting phenomenon will be described. In the following running on a downhill road, when the deceleration effect of the own vehicle's engine brake is smaller than the deceleration effect of the preceding vehicle's engine brake, the vehicle gradually approaches the preceding vehicle to satisfy the shift-down condition and shift down. Further, there is a case where the occupant of the preceding vehicle performs a brake operation or a downshift while disliked an increase in speed. At this time, the occupant approaches the preceding vehicle to satisfy the downshift condition and shift down.

When the effect of deceleration by the engine brake becomes larger than that of the preceding vehicle due to the downshift, the distance between the preceding vehicle and the preceding vehicle is increased, and the upshift is performed while satisfying the upshift condition. Also, when the occupant of the preceding vehicle releases the brake operation from a state in which the occupant brakes and decelerates, the speed of the preceding vehicle increases due to the downhill road, the inter-vehicle distance increases, and the shift-up condition is satisfied, and the shift-up is performed. When you shift up, you approach the preceding car every time, and shift down. Shift hunting occurs by repeating such an operation.

This shift hunting phenomenon is caused by the difference in the deceleration effect of the engine brake when the throttle is fully closed as described above. Further, on a downhill road, shift hunting due to a brake operation of a preceding vehicle is more likely to occur than on a flat road. If a large value is set in SG2 of the above-described shift-up condition, shift hunting can be prevented, but the shift shock at the time of shift-up is undesirably large.

Therefore, in this embodiment, the gradient of the road surface is estimated, and if it is determined that the road surface gradient exceeds a predetermined value, that is, if it is determined that the vehicle is traveling on a steep downhill to some extent, the upshift after the downshift is performed. To prevent shift hunting on downhill roads.

As described above, in this embodiment, since the disturbance is estimated by the vehicle speed servo system to which the robust model matching control method is applied, the road surface gradient is estimated based on the estimated disturbance value. Here, the disturbance may be caused by a change in running wind pressure in addition to the road surface gradient.However, since the disturbance estimation value during the following traveling may be mainly represented by the road surface gradient, the disturbance estimation is performed in this embodiment. The road gradient is determined based on the value.

In this embodiment, when (estimated disturbance value) ≦ SG3, upshifting is prohibited. The disturbance estimation value becomes negative on a down slope and positive on an up slope. That is, (disturbance estimated value) ≦ SG3 means a downhill with a steep gradient to some extent. As long as the shift-up prohibition condition is satisfied, the vehicle will not be shifted up even if the shift-up condition is satisfied.Therefore, after approaching the preceding vehicle on a downhill road and shifting down, the vehicle is not shifted up until the road gradient becomes gentle, Hunting is prevented from occurring.

FIG. 4 is a flowchart showing a shift control routine. The shift down and shift up operations of the embodiment will be described with reference to this flowchart. In step 1, the current shift position of the automatic transmission 4 is confirmed, and
If the speed is high, the process proceeds to step 2 to determine shift down. If the speed is 3 speed, the process proceeds to step 5 to determine shift up.

When the vehicle is traveling at the fourth speed, the deceleration force margin is compared with the threshold value SG1 in step 2, and if the deceleration force margin is equal to or smaller than the threshold value SG1, the routine proceeds to step 3. On the other hand, when the deceleration force margin is larger than the threshold value SG1,
It is determined that the deceleration force is sufficient even at the current shift position (fourth speed), and the shift control routine ends without downshifting.

If the deceleration force is insufficient at the current shift position, it is checked in step 3 whether the relative speed with respect to the preceding vehicle is 0 or less, that is, whether or not the vehicle is approaching the preceding vehicle. If the relative speed is greater than 0, the vehicle is moving away from the preceding vehicle, and thus the shift control routine ends without downshifting. If the deceleration force margin is equal to or less than the threshold value SG1 and there is no margin in the deceleration force, and if the relative speed is equal to or less than 0 and approaching the preceding vehicle, the above-described shift-down condition is satisfied. Send to automatic transmission 4. Upon receiving the OD cancel signal, the automatic transmission 4 shifts down from fourth speed to third speed.

If the vehicle is currently running at the third speed, the deceleration margin is compared with a threshold value SG2 at step 5. If the margin for deceleration force is equal to or larger than the threshold value SG2, the process proceeds to step 6, and if not, the process of the shift control routine ends. In step 6, the relative speed with the preceding vehicle is 0
Check if it is bigger, that is, if you are moving away from the preceding car. If the vehicle is approaching the preceding vehicle at a relative speed of 0 or less, the shift control routine ends without upshifting. If the deceleration force margin is greater than or equal to the threshold value SG2 and the deceleration force has a margin and the relative speed is greater than 0 and is far from the preceding vehicle, the shift-up condition is satisfied, and the process proceeds to step S7.

If the upshift condition is satisfied, it is checked in step 7 whether the upshift inhibition condition described above is satisfied. That is, the disturbance estimation value is set to the threshold value SG.
If the estimated disturbance value is equal to or smaller than the threshold value SG3, it is determined that the vehicle is traveling on a downhill with a large gradient, and the processing of the shift control routine is terminated without releasing the OD cancel signal. That is, upshifting is prohibited when the vehicle is traveling on a downhill with a predetermined slope or higher. On the other hand, if the disturbance estimation value is larger than the threshold value SG3, the OD cancel signal is canceled in step S8. The automatic transmission 4 from which the OD cancel signal has been released shifts up from third speed to fourth speed in accordance with a shift pattern determined by the vehicle speed, the throttle opening, and the like.

FIG. 5 shows the result of performing follow-up control on a preceding vehicle traveling at a speed of about 65 km / h on a down grade, with shift hunting according to this embodiment (a).
And (b) without the shift hunting countermeasure by the conventional device are shown in comparison. Note that the thresholds SG1, SG
2, -3 [m / s]
s], -0.25 [m / s], and -0.5 [m / ss]. As is clear from FIG. 5, when the shift hunting countermeasure according to this embodiment is performed, the estimated disturbance value is −0.5 [m / ss] even if the shift-up condition is satisfied.
In the following cases, upshifting is not performed, so that shift hunting does not occur.

As described above, the gradient of the road surface is estimated, and the shift-up after the shift-down is prohibited while the road gradient exceeds a predetermined value, that is, until the gradient becomes moderate to some extent. Hunting can be prevented,
Shift down and shift up can be performed according to the driver's driving sensation.

In the configuration of the above embodiment, the inter-vehicle distance sensor 1 replaces the inter-vehicle distance detection means with the vehicle speed sensor 2.
The following control controller 5 constitutes an inter-vehicle distance control means, a vehicle speed control means, a drive control means, a road surface gradient estimating means and a shift-up prohibiting means.

In the above-described embodiment, the estimated disturbance value calculated by the vehicle speed servo system is used as the estimated value of the road surface gradient. However, the method of estimating the road surface gradient is not limited to the above embodiment. Further, in the above-described embodiment, the threshold value SG3, which is a criterion for prohibiting the upshift, is set to a fixed value. However, another threshold value may be set at the beginning and end of the downward slope to provide hysteresis. In this case, shift hunting can be more reliably prevented. Further, in the above-described embodiment, the shift control of the third speed and the fourth speed (OD) in the automatic transmission having four forward speeds has been described as an example. However, the number of shift speeds and the shift position to be subjected to the shift control are as follows. It is not limited to the above embodiment.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of an inter-vehicle distance control system and a vehicle speed control system according to one embodiment.

FIG. 3 is a diagram showing a configuration of a vehicle speed servo system based on a robust model matching control method.

FIG. 4 is a flowchart illustrating a shift control routine according to one embodiment.

FIG. 5 is a diagram illustrating shift control results according to an embodiment and a conventional device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inter-vehicle distance sensor 2 vehicle speed sensor 3 throttle actuator 4 automatic transmission 5 following control controller 6 braking device 11 ranging signal processing unit 21 vehicle speed signal processing unit 50 preceding vehicle following control unit 51 vehicle speed control unit 501 relative speed calculation unit 502 inter-vehicle distance Control unit 503 Target inter-vehicle distance setting unit 511 Vehicle speed servo unit 512 Throttle servo unit 513 Shift control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // F16H 61/16 F16H 61/16 F16H 59:44 59:66

Claims (3)

[Claims] 1. An inter-vehicle distance detecting means for detecting an inter-vehicle distance from a preceding vehicle; an inter-vehicle distance control means for calculating a target vehicle speed for making a detected inter-vehicle distance equal to a target inter-vehicle distance; Vehicle speed detection means, vehicle speed control means for calculating a target braking / driving force for matching the detected value of the own vehicle speed to the target vehicle speed, and drive control means for driving and controlling the prime mover, the transmission, and the braking device according to the target braking / driving force. A preceding vehicle follow-up control device, comprising: road surface gradient estimating means for estimating a road surface gradient; and shift-up prohibiting means for prohibiting shift-up when a road surface gradient estimated value on a downhill road is equal to or more than a predetermined value. 2. The preceding vehicle follow-up control device according to claim 1, wherein the vehicle speed control means includes a disturbance compensation means for estimating a disturbance applied to the vehicle during traveling and compensating a driving force of the vehicle based on the disturbance estimation value. The preceding vehicle following control device, wherein the road surface gradient estimating means estimates a road surface gradient based on a disturbance estimated value estimated by the disturbance compensating means. 3. The preceding vehicle follow-up control device according to claim 1, wherein a hysteresis is provided to the predetermined value serving as a criterion for determining whether an upshift is prohibited.