Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-12-13
2001-07-24
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S079000, C180S197000
Reexamination Certificate
active
06266604
ABSTRACT:
The invention relates to a method for cruise control for a motor vehicle.
Such a method is known, for example, from Patent Specification DE 44 43 219 C1. Laid-Open Specification DE 195 08 492 A1, for example, also describes such a method. In the case of these cruise control methods, the actual speed is varied, as long as it is still relatively far away from the set speed, by acceleration regulation in the direction of the set speed, which can be predetermined. If it has then reached a speed regulation interval which can be predetermined and includes the set speed, it is regulated at the set speed by speed regulation. This can be achieved, for example, by a cruise control device which has an acceleration control loop and a speed control loop in parallel, between which it is possible to switch as appropriate. The acceleration control loop is used primarily for changing to the set speed which, depending on the situation, may also be a maximum speed, while the speed control loop is used primarily for driving at a steady speed.
By using the acceleration control loop, the actual speed can be varied smoothly in the direction of the set speed, when it is still relatively far away from the set speed. The changeover to speed regulation in good time before reaching the set speed allows the actual speed to approach the set speed optimally, without any noticeable overshoot effects.
A plurality of different control parameter sets, which depend on the gears selected in the motor vehicle transmission system are in each case available for acceleration regulation and speed regulation, which are switched between when gear changes are carried out. These control parameter sets are normally matched to steady-state driving, which is related to driving on level ground. The changeover from acceleration regulation to speed regulation is made when the actual speed enters the predetermined speed regulation interval, that is to say when the magnitude of the difference between the actual and set speeds is less than the value which can be predetermined and which is predetermined to be equal to or greater than zero. This changeover difference threshold value is selected such that the regulation stabilizes in an optimum manner with the selected control parameters when driving on level ground, that is to say the actual speed approaches the set speed as quickly and as uniformly as possible, without any noticeable control oscillations. On the other hand, when driving on a gradient, there is a risk that this control parameter matching to driving on level ground will lead to a noticeably worse transient response, with considerable overshoots, owing to the excess acceleration resulting from the gradient, since the control parameters are not optimized for this driving situation.
A method for controlling and limiting the speed of a motor vehicle is known from DE 195 47 716 A1. The changeover from acceleration regulation to speed regulation is carried out when the difference between the set speed and the actual speed falls below a specific value. During this changeover, when driving up hills, an adaptation value is produced which is dependent on the load acting on the motor vehicle and is applied as an additional element to the output signal of the speed regulator. This measure is intended to suppress interruptions in the control response when driving up hills. For routes with a significant downward gradient, it is impossible to reliably prevent significant regulation overshoots using this method.
DE 692 08 092 T2 describes a system for speed regulation with variable gain as a function of the speed error. Regulator coefficients are read from a memory depending on how the motor vehicle is being operated. No changeover between an acceleration regulator and a speed regulator is envisaged in this case.
The invention is based on the technical problem of providing a cruise control method of the type mentioned initially, which allows the regulation to have comparably good transient response, without any significant overshoots in the same way as when driving on level ground when driving on routes with noticeable roadway gradients, in particular routes with a noticeable downward gradient.
SUMMARY OF THE INVENTION
The invention solves the problem by providing a cruise control method wherein changing from acceleration regulation to speed regulation, the actual value of a roadway gradient characteristic is determined, that is to say a characteristic which is a measure of the instantaneous roadway gradient. The speed control parameter set used for subsequent speed regulation is then selected appropriately, matched to the roadway gradient, as a function of the determined actual value of the roadway gradient characteristic, from a plurality of speed control parameters sets which are predetermined differently for different possible values of the roadway gradient characteristic. For example, the normal standard speed parameter set, which is optimum for this purpose, can be used when driving on level ground, while a speed control parameter set which differs from this and is better matched to the existing negative roadway gradient value can be used when driving down a gradient, and this latter parameter set then leads to the same optimum transient response for this driving situation as the standard speed control parameter set does when driving on level ground.
In another aspect of the invention, the acceleration difference between the actual acceleration and a normal acceleration value which can be predetermined is used as the roadway gradient characteristic. The normal acceleration value in this case represents that acceleration value which the cruise control reaches when driving on level ground in the situation when the regulation has an optimum transient response, at the time of the changeover from acceleration regulation to speed regulation. In a further refinement of this method, the normal acceleration value is predetermined variably as a function of the actual speed and a selected transmission gear, for example being determined from characteristics that are dependent on the gear, using the actual speed. The control parameter set used for the initiated speed regulation is then preferably likewise defined on the basis of characteristics which are dependent on the gear, taking account of the determined acceleration difference between the actual acceleration at the changeover time and the normal acceleration value.
In yet another aspect of the invention, the speed control parameter set selected for subsequent speed regulation on changing over from acceleration regulation to speed regulation is maintained for a time period which can be predetermined, after which a smooth change is then made to the standard speed control parameter set, that is to say without any discontinuities in the speed regulator output signal.
REFERENCES:
patent: 1307038 (1919-06-01), Bruce
patent: 1307039 (1919-06-01), Casler
patent: 4736813 (1988-04-01), Hayama et al.
patent: 4835696 (1989-05-01), Suzuki et al.
patent: 5329455 (1994-07-01), Oo et al.
patent: 5394954 (1995-03-01), Tashiro et al.
patent: 5541843 (1996-07-01), Yamaguchi et al.
patent: 5663880 (1997-09-01), Saur et al.
patent: 5665026 (1997-09-01), Linden
patent: 5774820 (1998-06-01), Linden et al.
patent: 4443219C1 (1996-06-01), None
patent: 69208092T (1996-06-01), None
patent: 19508492A (1996-09-01), None
patent: 19547716A (1997-06-01), None
Calcaterra Mark P.
Daimler-Chrysler AG
Nguyen Tan
LandOfFree
Method for cruise control for a motor vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for cruise control for a motor vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for cruise control for a motor vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2468173