Distance-regulating system for automotive vehicles.

The invention relates to an adaptive cruise control system for motor vehicles according to the preamble of the main claim.

Individual traffic with motor vehicles in particular has in recent years a strong growth on, which led to a heavy load of traffic routes and an increase in the total fuel consumption of individual traffic. The construction of roads could with this growth for reasons of environmental protection and the relatively dense population and development, such as Europe, not compete to the extent needed.

It is therefore necessary to use one hand the roads given so that the individual transport is better appropriately allocated to this; On the other hand there is the need of at least one part to relieve the driver of the motor vehicles of their in guiding the vehicle to them, must be clarified. Likewise, it appears necessary to reduce the fuel consumption of individual traffic overall.

As part of on this issue ongoing research project (Prometheus), which is supported by the European automotive industry and funded by the European Community, it has been proposed to join together each multiple vehicles to a vehicle association and, with a relatively small distance from one another, herfahren on a traffic route in succession allow.

This is on the one hand ensures that the motor vehicles require little space on a busy route, on the other hand at least by distance control between vehicles, drivers noticeably relieved. Due to the relatively small distance between the vehicles (ie, a vehicle always drives the "slipstream" of the preceding motor vehicle) also results in a significant saving of fuel consumed since the overall efficiency of the vehicle association by the reduced air resistance to individually moving vehicles is improved.

Methods and devices have been developed for distance control between cars already, which measure the distance to each preceding motor vehicle and a driving or braking performance of the vehicle control so that sets a target distance. In DE-OS 35 01 032 to measure the distance, for example, by an optical E rfassen of arranged on the lane markings made ​​with information about those measurements between two vehicles via transmitters and receivers are interchangeable.

However, the measurement and Einregelung the distance requires a certain delay time for signal acquisition (and transmission) and When adjusting, since the dynamics of such a control system, even if ever so good control, is not negligible. This results in particular in a larger vehicle association unavoidable vibrations of the distance between vehicles, representing itself a stationary observer as a "Zieharmonikaeffekt" and can swaying worst.

It is an object of the invention to provide an adaptive cruise control system for motor vehicles, which avoids these disadvantages and permits motor vehicles can follow in larger vehicles Association a vehicle dressing Battle Scene at the motor vehicle without significant oscillations of the distances between the vehicles themselves.

The invention is solved by the characterizing features of claim 1. Further embodiments of the invention are contained in the subclaims.

The advantages of Erfidnung are seen primarily in the fact that a specification of a time change of the vehicle speed (target acceleration) within a motor vehicle of the automobile association takes place and a drive or delay performance of each motor vehicle is controlled within the vehicle association so that the change in its onboard speed (actual acceleration) of the target acceleration with minimal Differnz or predetermined dynamics is tracked. This ensures that vibrations of the distance between the vehicles only can not build because all vehicles a predetermined desired value (target acceleration) virtually instantaneously, ie without following or with the same delay.

The invention is illustrated by way of example illustrated in a drawing.

In the figure is shown at 1 is a vehicle combination comprising a plurality of motor vehicles hintereinanderherfahrenden 2, 3, 4; the vehicles 2, 3, 4 move along a roadway 5. The motor vehicles 2, 3, 4 are each equipped with an actuator 6 and a braking device 7, the drive 6 preferably with an internal combustion engine and a downstream thereof, preferably with tractive force interruption-free gear changes working automatic transmission takes place. The motor vehicles 2, 3, 4 further include a controller 8, and a measuring device 9 for the vehicle's velocity v and a radio transmitter 10 and a receiver system 11. The control means 8 of the vehicles 2, 3, 4 can use the transmitter 10 and the reception system 11 exchange information; the transmission of information can take place via electromagnetic or acoustic wave propagation or via an inductive coupling to a disposed in the roadway 5 search wire 12th Every motor vehicle 2, 3, 4 is occupied by a driver 13, which can act on the drive 6 and brake device 7 via the control device. 8

The control of the drive power of the drive 6 and the braking performance of the braking device 7 now takes place by the control device 8. To this end, in a motor vehicle of the vehicle association a specification of a time change of the vehicle's own speed dvs / dt, that is, a target acceleration carried out; the word target acceleration is here, however, are not alone for a positive temporal change in the vehicle's own speed, but also a negative, ie, a vehicle deceleration.

The target acceleration dvs / dt is now coupled via the transmitter 10 in the guide cable 12 and transmitted to the receivers 11 of other motor vehicles. The controller 8 for all motor vehicles 2, 3, 4 detect via the measuring 9 the vehicle's velocity v and determine from its temporal changes (actual acceleration) dvi / dt. The ECU 8 regulate the drive and the delay performance so that the change in the vehicle's own speed dvi / dt of them controlled motor vehicle, the target acceleration dvs / dt is tracked with minimal difference or a prior given dynamics.

The target accelerations are primarily predetermined by a driver of the vehicle combination Battle Scene ends motor vehicle 2 and / or an autopilot and / or a traffic control system directly and / or determined from the operating element signals and / or operating or driving parameters of this motor vehicle. 2 The for the scheme underlying the further motor vehicles forwarded target acceleration dvs / dt can be limited by the controller 8 in value, however, if appropriate, if any of the participating vehicle combination 1 Motor vehicles 2, 3, 4 can not follow this target acceleration.

For this purpose, each received propelled vehicle in association automobile as it enters this the Battle Scene haves and other motor vehicles 2, 3, 4 limits its maximum or minimum-applicable change his vehicle's speed dvi / dt. The controller 8 of Battle Scene ends automobile is now the target acceleration dvs / dt so ago that it always moves within the magnitude lowest limits.

But it may happen that a motor vehicle 3, 4 an emergency must initiate within the vehicle Association 1 for example, by a suddenly emergent obstacle. For this purpose, the vehicle combination is dissolved, and the emergency braking introductory automotive accepts the specification of the target acceleration dvs / dt for the following vehicles.

Likewise, it may happen that one of the motor vehicles within the automobile association can currently not be accepted in a delay of the setting, for example, due to a reduced coefficient of friction between the wheel and the road surface, so that its distance to the vehicle in front decreases. Under the given possibility this vehicle takes over the setting of the target acceleration dvs / dt, at least until it reaches the original target again. It is this also possible that the preceding motor vehicles Pufferungszwecken temporarily temporarily reduce their distances respectively to preceding motor vehicle at least.

In the event that one of the vehicles can currently not be accepted at an acceleration of the target, for example by an occurring traction or a problem with the drive 6, this takes at least as long as the specification of the reference acceleration dvs / dt until the original specification by the spearheading automobile 2 reached again. It is also conceivable that there are at least as long accepts the specification of the aimed acceleration DVS / dt for the following motor vehicles, to the broken vehicle combination is brought together again. Control of driving or stopping power of all motor vehicles are designed such that they each establish at the same time; they receive information, check with a time delay, which means the target acceleration dvs / account, inter alia, the time to transmit the data, dt the following motor vehicles. As in the case of transmission of information on acoustic wave propagation a signal propagation time can not be neglected, it may be advisable to choose this time delay depends on the position of the vehicle within the vehicle association and the distances between the vehicles. The scheme of another motor vehicle immediately preceding motor vehicle sets this one delayed by the signal propagation time.

The Regelung- or tracking of the time change of the vehicle's own speed dvi / dt of a motor vehicle to the target acceleration dvs / dt can be superimposed for safety reasons a distance and / or speed fine control. However, this only comes into effect when the distance to a vehicle ahead exceeds or drops below a predetermined tolerance range. In effect of the distance and / or speed- fine control in a motor vehicle within the vehicle Association 1 This assumes currently specifying the target acceleration dvs / dt for the following vehicles.

In the event that the control systems operate with negligible dynamic or upon the occurrence of drive slip at the vehicle Association Battle Scene at the motor vehicle 2, the target acceleration dvs / dt equal to the actual acceleration dvi / dt of the vehicle combination Battle Scene ends the vehicle will be set. If, in addition, the distance between the vehicles are adjusted depending on speed, so it makes sense that a driver 13 of the vehicle combination Battle Scene ends motor vehicle 2 and / or a traffic control system, a target speed vs pretending or that this is determined from List Control control signals. The control device 2 of the vehicle combination Battle Scene ends motor vehicle 2 used to determine a target acceleration dvs / dt, and a time course, which this target acceleration to accept and a safety time delay tvs, which leads to an intended speed-dependent safety distance to a moving directly in front of him the motor vehicle; these values ​​are transmitted to the following vehicles. The tracking of the actual acceleration dvi / dt of the target acceleration dvs / dt of a motor vehicle (3, 4) is followed by that of the immediately preceding motor vehicle with this safety delay tvs, resulting in the desired distances between the vehicles 2, 3 4. (Not shown), and makes the driver as "restoring force" noticeable.

In FIG. 4 characteristics are shown for this purpose. The is performing as a characteristic curve 16 is initially shown for driving straight ahead. You can, of course, as with power steering systems common to their form in the manner shown, depending on the vehicle speed change (characteristic 17), so that the restoring force increases with increasing speed. In the illustration shown positive numerical values ​​for left drive and negative numbers for legal journey on this day. The maximum steering angles are designated by plus or minus lem lem and the maximum actuating forces with plus or minus rkm rkm.

When driving straight ahead the first force rk is equal to zero. If the driver wishes to leave this course, so he must exert a steering movements le corresponding force. It is now assumed that a straight running following left turn requires a steering angle of dle. Did the driver still go straight, so he would have to provide by the characteristic curve 16 the steering lea assigned (re) force drk. To maintain the target rate, the characteristic example by the amount drk in plus rk-direction will be shifted so that it merges with the new characteristic curve 18 (FIG. 5); the force rk for the steering lea is hereby turn to zero. This can also be achieved, of course, by the curve in the manner shown in Figure 6 in plus le-direction "distorted" is. the maximum restoring force at plus or minus lem lem remains the same. Here again, a departure from the intended course is possible, for example, to avoid a suddenly appearing obstacle; but it must be applied a corresponding restoring force.