Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-10-14
2001-11-20
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S028000, C701S096000, C701S220000, C340S903000
Reexamination Certificate
active
06321159
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a driving lane tracking system for guiding a traveling motor vehicle so as to stay within a prescribed driving lane.
BACKGROUND OF THE INVENTION
In recent years, a number of proposals have been made to enable a motor vehicle to automatically track a driving lane. There are two known major control principles.
(1) The vehicle is equipped with a video camera, typically consisting of a CCD camera, which gathers information on the current position of the vehicle, and sensors for detecting certain dynamic state variables of the vehicle. The changes in the curvature of the road path are treated as unknown disturbances. The vehicle follows the driving lane by receiving information on the deviation of the vehicle position from the center of the driving lane and the dynamic state variables of the vehicle as a feedback signal. Refer, for instance, to “Automatic Path Tracking Using Linear Quadratic Control Theory—Control Method for a Curved Path”, by H. Furusho and H. Mouri, Proceedings of JSAE Semi-Annual Convention, No.972, May 1997, pp. 49-52.
(2) The vehicle is equipped with a video camera which gathers information on the road path lying ahead of the vehicle, and sensors for detecting certain dynamic state variables of the vehicle. A preview control based on the predicted course of the road path is carried out in combination with the feedback control based on the dynamic state variables of the vehicle. Refer, for instance, to “Preview Control for Vehicle Lateral Guidance in Highway Automation”, by H. Peng and M. Tomizuka, ASME Journal of Dynamic Systems, Measurement and Control, December 1993, Vol. 115, pp. 679-686.
According to the first principle (1), because the control process relies on the current course information, there is some difficulty in achieving an optimum selection of control parameters for successfully tracking the curved path of the road, and a somewhat excessive time delay or overshoot is inevitable. In the case of the second principle (2), a smooth tracking of the course of the road may be possible, but the state variables for the feedback control include those which cannot be measured directly, and the high-speed estimation of such state variables requires a high speed computing unit. Therefore, the system tends to be unacceptably complex and expensive.
BRIEF SUMMARY OF THE INVENTION
In view of such problems of the prior art, a primary object of the present invention is to provide a driving lane tracking system which demonstrates a favorable tracking capability and can be implemented with a relatively simple structure.
A second object of the present invention is to provide a driving lane tracking system which can execute a prediction control by using only such variable that can be measured both easily and accurately.
According to the present invention, such objects can be accomplished by providing a driving lane tracking system, comprising: road path previewing means for detecting a current position of a vehicle with respect to a road path, and previewing a target road path lying a certain distance ahead of a vehicle; a steering angle sensor for detecting a current steering angle of the vehicle; a storage unit for storing data obtained from the road path previewing means and the steering angle sensor; a steering actuator which at least assists a steering effort made by a vehicle operator; and a control unit for controlling the steering actuator so as to optimize a lateral deviation of the vehicle with respect to the target road path according to data on the past, current and target road path.
Thus, preview information is obtained by processing data from the preview means such as image data of a CCD camera, and it is treated as a known disturbance. Then, models for a vehicle and a target road path, typically consisting of DARMA (deterministic auto-regressive moving average) models are prepared so as to give a relationship between a front wheel steering angle command and a lateral deviation of the vehicle. Preferably, an extended generalized predictive control theory is applied to these models so as to compensate for tracking errors that may arise as a result of the known disturbance. For details of the generalized predictive control theory, reference should be made to “Generalized Predictive Control—Part I, The Basic Algorithm”, by D. W. Clark, C. Mohtadi, and P. S. Tuffs, Automatica, Vol. 23, No. 2, pp. 137-148, 1987, and “Generalized Predictive Control—Part II, Extensions and Interpretations”, by D. W. Clark, C. Mohtadi, and P. S. Tuffs, Automatica, Vol. 23, pp. 149-160, 1987.
Typically, the road path previewing means comprises an electronic camera mounted on the vehicle which is adapted to identify the road path by detecting a line marked on a road to define a driving lane. Additionally or alternatively, the road path previewing means may comprise a navigation system which can identify a current vehicle position in relation to a map incorporated therein. The navigation system may be either a global positioning system using satellites and incorporated with map information or an inertial positioning system likewise incorporated with map information. The vehicle may further comprise a radar device for detecting other objects on the road such as other motor vehicles so that the vehicle may avoid coming undesirably close to other vehicles while tracking the road path. The output of the control unit may either wholly control the steering action or apply a supplemental or otherwise assistive steering torque reaction to the steering wheel so as to aid the effort of the vehicle operator to track the road path.
REFERENCES:
patent: 5934399 (1999-08-01), Iiboshi et al.
Clarke, D.W. et al., “Generalized Predictive Control—Part I. The Basic Algorithm*,”Automatica, vol. 23, No. 2, pp. 137-148 (1987).
Clarke, D.W. et al., “Generalized Predictive Control—Part II. Extensions and Interpretations*,”Automatica, vol. 23, No. 2, pp. 149-160 (1987).
Peng, H., “Preview Control for Vehicle Lateral Guidance in Highway Automation,”Journal of Dynamic Systems, Measurement, and Control, vol. 115, pp. 679-686 (Dec. 1993).
Nohtomi, S. and Horiuchi, S., “A Path Tracking Control System Using Generalized Predictive Control Theory,” Proceeding of JSAE Semi-Annual Convention, No. 62-98, pp. 9-12 (Oct. 20, 1998).
Mouri, H. and Furusho, H., “Automatic Path Tracking Using Linear Quadratic Control Theory—Control Method for a Straight Path,” Proceedings of JSAE Semi-Annual Convention, pp. 45-48 (May 1997).
Furusho, H. and Mour, H., “Automatic Path Tracking Using Linear Quadratic Control Theory—Control Method for a Curved Path,” Proceedings of JSAE Semi-Annual Convention, pp. 49-52 (May 1997).
Horiuchi Shinichiro
Nohtomi Shinya
Cuchlinski Jr. William A.
Donnelly Arthur D.
Honda Giken Kogyo Kabushiki Kaisha
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