Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Patent
1997-05-08
1998-07-14
Nguyen, Tan Q.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
701 41, 701202, 701217, 180408, 180415, G06F16500, G05D 102
Patent
active
057818703
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a vehicle guidance system for storing position data pertaining to a predetermined driving course, and for guiding the vehicle along the predetermined driving course by controlling the steering angle of the vehicle on the basis of this position data.
BACKGROUND ART
Several systems for guiding vehicles along predetermined driving courses have been developed and submitted for patent application in the past.
Japanese Patent Publications 5-22925 and 5-22926 teach a technique of approximating the driving course by connecting a plurality of straight line segments and guiding the vehicle along these straight line segments.
While the technique taught in these publications has the advantage that calculation of the vehicle steering angle or the like is easy since the vehicle needs only to move forward in a straight line, it has the drawback that, since curved driving course paths are approximated by straight lines, the vehicle does not follow the predetermined driving course in an exact manner.
Further, the technique taught in the aforementioned publications sets the vehicle steering angle without regard for current vehicle speed.
Thus, when the vehicle is traveling at high speed, the steering angle can be too great, creating the possibility of oversteering and, in some cases, causing the vehicle to deviate from the curved driving course. Conversely, when the vehicle is traveling at low speed, the steering angle can be too small, creating the possibility of understeering and, in some cases, causing the vehicle to deviate from the curved driving course.
Further, in the technique taught in the aforementioned publications, the steering angle when the vehicle follows a straight-line course without deviation is set to zero for reasons pertaining to the steering angle calculation process.
However, in the case of a vehicle such as a dump truck, the alignment of the four wheels of the vehicle can change depending on the load and load distribution. When the alignment changes, continuing to move with the steering angle set at zero can cause the vehicle to deviate from a straight-line course. This presents significant practical problems.
Japanese Patent Publication 5-503775 teaches calculating the steering angle by plotting from the current position a smoothly linked path, expressed by a polynomial of degree 5, over the driving course and guiding the vehicle along this path.
While the technique taught in this publication does take into account travel over a curved driving course, the calculations are quite complex and time-consuming.
Like the aforementioned Japanese Patent Publications 5-22925 and 5-22926, the technique taught in the aforementioned publication sets the vehicle steering angle without regard for current vehicle speed. This gives rise to the possibility of deviation from a curved driving course.
Also, like the aforementioned Japanese Patent Publications 5-22925 and 5-22926, the steering angle when the vehicle follows a straight-line course without deviation is set to zero, so if there is not perfect alignment between the front and rear wheels of the vehicle, it becomes extremely difficult to prevent the vehicle from traveling along the straight-line course without deviation.
Thus, conventional techniques have the drawback of being incapable of affording travel in an exact manner over a curved driving course by means of a simple process.
They also have the problem of deviation from a curved driving course depending on vehicle speed.
A further problem is that changes in vehicle alignment can result in deviation from the predetermined course, even when the driving course is straight course.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a system that can overcome these problems.
The first invention of this invention is intended to accurately guide the vehicle over a curved driving course by means of a simple process, and to prevent the vehicle from deviating from a curved driving course regardless of vehicle speed.
These objects
REFERENCES:
patent: 4600999 (1986-07-01), Ito et al.
patent: 4628454 (1986-12-01), Ito
patent: 4700427 (1987-10-01), Knepper
patent: 4803640 (1989-02-01), Mitomi et al.
patent: 4860209 (1989-08-01), Sugimoto et al.
patent: 5264709 (1993-11-01), Kamimura et al.
Komatsu Ltd.
Nguyen Tan Q.
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