Communications: electrical – Land vehicle alarms or indicators – Of collision or contact with external object
Reexamination Certificate
1999-04-22
2001-10-09
Tong, Nina (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of collision or contact with external object
C340S903000, C180S169000, C342S070000, C367S909000
Reexamination Certificate
active
06300865
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a process for recognizing the course of the road ahead for a motor vehicle, in which the velocity of the vehicle is determined and the position and the velocity of objects located ahead are determined by a radar sensor system with rigidly oriented antennas, fixed targets are separated in discrete angle ranges, and the distances from these fixed targets (X) are determined as current distances between the side of the road and the motor vehicle and are used as characteristics for a nonlinear regression.
BACKGROUND OF THE INVENTION
Such a process has been known from U.S. Pat. No. 5,343,206.
To increase driving safety and comfort, motor vehicles are equipped with distance control means for automatically maintaining the distance as well as with warning means for the driver. Equipping the vehicle with radar and image-processing devices for distance measurement for this purpose has been known. The position and the velocity of objects located ahead are determined from the measured values, and a safety distance is maintained by automatically controlling the velocity and by warning the driver. It is possible as a result to automatically follow a vehicle proceeding ahead in the same lane. However, it is necessary that the object relevant for the automatic distance control be always identified from the large number of objects located ahead. Besides the determination of the position of the objects detected, it is therefore also necessary to know the course of the road in order to check whether an object is located in the same lane as the vehicle. An incorrect assignment, even if it occurs only briefly, may lead to needless braking or acceleration maneuvers in the case of controlled travel, which considerably compromise the driving comfort.
As long as the lane maintains a constant direction, the direction of the vehicle may be used to determine the lane. It has been known from DE 30 34 199 A1 that the current steering angle of the vehicle can be evaluated to recognize curves. The drawback of this method is that curves cannot be indicated in advance, because the steering angle must first exceed a certain threshold value, but this happens only when the vehicle is already in a curve. In the case of changes in the direction of the lane, e.g., while entering and leaving a curve, a forward-looking recognition of the road is needed. The measure of detecting curves, which is described in U.S. Pat. No. 4,158,841, uses pivotable search antennas controlled by the steering angle. However, this solution can be embodied in a mechanically complicated manner only and it is correspondingly expensive. According to DE 44 18 122 A1, an image-processing device is used for the forward-looking recognition of the curve in addition to the radar sensor system. A process based on image processing, which is characterized by its ability to distinguish obstacles located on the collision course from other objects not located in the own lane, is likewise described in DE-OS 22 15 576. The movement of image structures, which occurs relative to the vehicle, is evaluated for this purpose. Objects not located on the collision course are distinguished from collision objects by their lateral movement, and the image structure of collision objects, without lateral movement, makes it possible to recognize the course of the road. However, the problem of the entry into curves has not been solved with this device, because the lateral movement necessary for the recognition begins only when the movement increases symmetrically. With this device, the sides of the road and thus the vehicle may already be in the curve with this device. The general drawback of image-processing systems (both optical and thermo-optical) compared with radar systems is the increased complexity of the sensor system because of the extreme dynamics of lighting occurring in nature, the short depth of penetration in fog, and the risk of contamination by road dirt.
The above-mentioned U.S. Pat. No. 5,343,206 describes a process for avoiding a collision between a vehicle and obstacles located in the lane. The estimation of the course of the road of the vehicle is performed as follows: The environment located ahead is scanned sector by sector at an angle of 40° by means of radar and all reflected targets are entered in a storage matrix called a map corresponding to the distance measured and the scanning angle. An attempt is made in the next step to determine the optimal parameters of the course of the road by adapting a mathematical model of the course of the road to all the targets entered on the map. This process fails in practice, because it contains the preparation of a map with very high resolution in terms of angle and distance, which cannot be accomplished with a rigid radar sensor system because of the limited angle resolution. Another weak point of this process is the assumption that the side of the road can always be recognized from reflecting objects. Conversely, no check is made to determine whether a detected target belongs to the side of the road. Targets which do not belong to the side of the road lead to unacceptable errors in the estimation of the parameters for the course of the road due to the fact that the targets used to estimate the course of the road are not checked to determine whether they belong to the side of the road.
SUMMARY AND OBJECTS OF THE INVENTION
The basic object of the present invention is to design the process described in the introduction such that a forward-looking recognition of the course of the road becomes possible by a special evaluation of the existing measured position and velocity data with the exclusive use of a radar sensor system with rigidly oriented search antennas without an additional optical sensor system. It shall be possible to use information on the direction of the vehicle for the correction.
According to the invention, a process is provided for recognizing the course of the road ahead for a motor vehicle. The velocity of this vehicle is determined and the position and velocity of objects located ahead of the vehicle in question are determined by a radar sensor system with rigidly oriented antennas. Fixed targets are separated in discrete angle ranges, and the distances from these fixed targets are determined as current distances between the side of the road and the motor vehicle and are used as characteristics for a nonlinear regression. The targets specific of the side of the road are determined from among the fixed targets in the discrete angle ranges by a threshold value comparison of the target amplitudes. An ordering filter, which filters the target with the shortest distance out of the roadside-specific targets determined in the angle range of a plurality of consecutive measurement cycles, is used to determine the distance between the side of the road and the motor vehicle in a discrete angle range. The targets determined in the discrete angle ranges are used as characteristics for the adaptive prediction of the curve type with a curve classifier.
A model-based Kalman filter, whose model is based on the a priori knowledge of the dynamics of the courses of roads, may be used to smooth the distances between the side of the road and the motor vehicle. A correction signal, which is obtained by the comparison of the current curve type of the vehicle with the curve type, which is predicted by the curve classifier and is time-delayed corresponding to the current velocity of the motor vehicle, may be sent continuously to the curve classifier. The curve classifier may be formed by a neuronal network. The weights of the neuronal network may be preset once by an off-line adaptation based on example situations. The weights of the neuronal network, predetermined on the basis of example situations before putting into operation, may be corrected by the correction signal during the operation.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a bet
Fechner Thomas
Hach Rainer
Daimler-Chrysler AG
McGlew and Tuttle , P.C.
Tong Nina
LandOfFree
Process for detecting the road conditions ahead for motor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for detecting the road conditions ahead for motor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for detecting the road conditions ahead for motor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2613439