Motor vehicles – With means responsive to speed of vehicle for maintaining...
Reexamination Certificate
2000-01-03
2001-08-14
Boehler, Anne Marie (Department: 3618)
Motor vehicles
With means responsive to speed of vehicle for maintaining...
C701S096000
Reexamination Certificate
active
06273204
ABSTRACT:
BACKGROUND OF THE INVENTION
Methods and arrangements for controlling the speed of vehicles are known from the state of the art in many variations. For example, SAE Paper No. 961010 entitled “Adaptive Cruise Control, System Aspects and Development Trends” (1996) discloses a road-speed controller which takes into account the distance to the vehicle ahead. The driver inputs the desired speed of the vehicle via an operator adjustable lever with the functions which are customary for road-speed controllers, such as set speed, resume speed, accelerate, et cetera. The desired speed is controlled in a manner comparable to a conventional vehicle road-speed controller when a forward vehicle is not present in that a desired acceleration is computed from the difference between the desired and driving speeds. If a radar system detects a forward vehicle, then the distance and the relative speed to this vehicle are determined. The control task in this case is that the relative speed is controlled to zero and simultaneously a desired spacing is maintained which is dependent upon speed. Parameters for determining the desired distance (time gap) are adjustable by the driver. This follow-up controller determines a desired acceleration from the above-mentioned variables. The desired acceleration is, however, limited by the desired acceleration of the road-speed control component so that the pregiven desired speed cannot be exceeded even in the follow-up control. Distance controllers and speed controllers provide desired values for the acceleration and deceleration, respectively, of the vehicle in dependence upon the operating state. These desired values are adjusted by influencing the engine of the vehicle and/or the brakes.
German patent publication 4,338,399 discloses a road-speed controller wherein a desired acceleration of the vehicle is computed on the basis of the difference between the desired and actual speeds. This computed desired acceleration serves as the basis of the vehicle control. The actual acceleration of the vehicle is controlled by controlling the engine and/or by actuating the wheel brakes of the vehicle in such a manner that it approaches the desired acceleration.
The configuration of a controller of this kind defines a compromise between rapid reaction to the input data and dragging reaction in order not to confuse the driver or make the driver insecure and/or to maintain comfort. For this reason, and as a rule, the acceleration and/or the acceleration change is significantly throttled compared to the possibilities of the vehicle. In this way, the acceleration and/or the change of the acceleration of the vehicle is limited; that is, it is not possible for the actual acceleration and/or acceleration change of the vehicle to exceed this limit. Accordingly, the vehicle does not accelerate faster than pregiven by the limit value. Here, the problem occurs that the acceleration dynamic of the controller often lies significantly below the expectation of the driver, for example, when the forward driver is highly accelerating or where there is a passing maneuver or a swerving maneuver.
SUMMARY OF THE INVENTION
It is an object of the invention to provide measures which improve the dynamic acceleration and/or deceleration for a road-speed control without making the driver insecure or reducing comfort.
The method of the invention is for controlling the road speed of a vehicle and includes the steps of: controlling the road speed in the context of a closed-loop control wherein an actual value is caused to approach a desired value; limiting a change of the road speed during the closed-loop control when there is a dynamic operating state; and, cancelling the limiting or setting the limiting to higher values in dependence upon the state of at least one switch element actuable by the driver. Depending upon the switching element, this limit value is either lifted so that an unlimited acceleration (that is, the maximum attainable by the vehicle) is inputted or a greater acceleration than the limit value is inputted.
The solution provided by the invention permits an intervention to increase the acceleration dynamic or deceleration dynamic of a road-speed control system. These terms describe the dynamic performance of the vehicle when the road speed control system is activated during the acceleration or deceleration.
It is especially advantageous that this intervention is carried out with an operator-controlled element actuable by the driver so that a confusing operation of the control system can be precluded. In this way, the driver is involved for changing the dynamic of the control system whereby a greater reliability for dynamic acceleration or deceleration is achieved.
It is especially advantageous to use the solution provided by the invention for a control system having follow-up control (ACC or adaptive cruise control). In addition to the normal driving mode, the driver can adjust a sporty driving mode with a control system of this kind. With the possibility for changing the limit value for the acceleration of the vehicle, the driver can exert influence on the dynamic performance of the control system. Thus, the driver can adjust to a sporty driving performance outside of the normal driving mode which is directed more toward a comfortable driving performance. In this sport mode, a higher acceleration or deceleration is permitted also when the road speed controller is active.
In a further embodiment of the road-speed controller with follow-up control, the limit values for the dynamic are changed in dependence upon the driver-type factor formed in a transmission control unit. It is the state of the art that a so-called driver-type factor is determined in the context of transmission control and, in dependence on this factor, the switching points of the automatic transmission can be changed. With respect to the types of drivers, one can at least distinguish between a sporty driver and a normal driver for whom a more comfortable adjustment of the transmission control is provided. In this way, the complexity is considerably reduced and the dynamic of the control system is automatically adapted to the driver performance. The driver-type factor is formed in one embodiment also by another unit (for example, the follow-up control unit).
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Winner Hermann
Witte Stefan
Boehler Anne Marie
Fischmann Bryan
Ottesen Walter
Robert & Bosch GmbH
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