Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Reexamination Certificate
2001-06-04
2003-03-25
Louis Jacques, Jacques (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
C701S025000, C701S026000, C701S210000, C701S209000, C180S168000, C318S568100, C318S587000, C348S118000, C348S119000
Reexamination Certificate
active
06539294
ABSTRACT:
TECHNICAL FIELD
This invention relates to a vehicle guidance system, and particularly to a system suitable for applications in cases where a plurality of unmanned off-road dump trucks are guided at a work site such as a mine.
BACKGROUND ART
Unmanned vehicle guidance systems are being broadly and practically implemented which guide the movements of unmanned vehicles such as unmanned off-road dump trucks at mining sites of extensive area in the interest of releasing from hard labor, lowering production costs, and reducing fuel consumption, etc.
These unmanned vehicles carry position measurement equipment that uses GPS (global positioning system) equipment or the like to measure travel positions thereof. At a monitoring station that monitors a plurality of unmanned vehicles, meanwhile, position data for travel courses that the unmanned vehicles are to travel over are determined by means of work site surveying and/or teaching, and stored in memory. When an unmanned vehicle is sent such travel course position data via radio communications or the like, that vehicle measures its own position (and direction) with the on-board position measuring equipment, and effects vehicle steering control so that it successively reaches positions on that travel course while comparing the measured current position with the successive positions on the travel course.
One widely employed method of acquiring the travel course position data noted here is a teaching method wherewith a manned vehicle designed for teaching is actually driven and the course run is stored in memory.
In such cases, the teaching vehicle actually travels over a course, and position data are acquired for a course extending from a starting point to a target point, or for a course that extends from the starting point, passes through the target point, and returns to a finish point, so that unmanned vehicles will pass through the target points that they are supposed to reach. Another method is to acquire only the position data for the target point by teaching and then generate the courses to be run from those target point position data.
Consider, for example, the,case diagrammed in
FIG. 8
where, at a mining site, there exists a dumping area
65
where an unmanned vehicle
2
is to perform the operation of transporting earth and dumping that earth, that is, an earth dumping operation. Position data for a travel course
71
that passes through a target dumping point
72
in that dumping area
65
are acquired by the teaching method.
Work sites such as mining sites of extensive area are usually unpaved, and the road surface conditions change from time to time in conjunction with the traveling of the unmanned vehicles
2
. Also, during the traveling of the unmanned vehicles
2
, the rock and earth loaded thereon sometimes fall onto the road surface. It sometimes happens, therefore, that potholes and/or mud is formed on the travel course obtained by teaching, making it very difficult for the vehicles to pass through. There are also cases where rocks and the like appear on travel courses obtained by teaching, making it impossible for vehicles to pass through. In this specification, the comprehensive term “obstacle(s)” is applied to all obstacles to vehicle travel resulting from potholes, mud, or fallen load.
In such cases, it is necessary to again conduct teaching for a new travel course that will avoid the obstacle or obstacles.
However, redoing the teaching operation every time the road surface condition changes or every time load falls from another unmanned vehicle results in the loading operations or dumping operations being interrupted and causes a sharp decline in work efficiency.
In the face of this, a method is being adopted wherewith, instead of avoiding conflict with the obstacles noted above by redoing the teaching operation, an obstacle
74
is detected by an obstacle detector
34
carried on the unmanned vehicle
2
while that vehicle is moving, as diagrammed in
FIG. 9
, so that each vehicle can individually alter the course it is traveling over.
In Japanese Patent Application Laid-Open No. 63-273916, Japanese Patent Application Laid-Open. No. 3-113516, and Japanese Patent Application Laid-Open No. 5-87608, for example, inventions are described wherewith obstacles ahead of a vehicle are detected by an obstacle detector carried by the vehicle, and the travel course is altered so as to avoid conflict with that detected obstacle.
Using the inventions described in the publications noted above, however, only obstacles in front of a vehicle within a range detectable by the obstacle detector can be detected. Other obstacles existing on the travel course after course alteration cannot be detected ahead of time. For that reason, when a vehicle starts to negotiate an altered travel course, there is a danger that conflicts will occur with such other obstacles.
The inventions described in the publications noted above are only able to detect obstacles of shapes that are detectable by an obstacle detector. Conversely, obstacles of a shape that is undetectable by the obstacle detector cannot be detected. Obstacle detectors are generally capable of detecting obstacles that bulge out from the road surface, that is, obstacles such as fallen load (rocks), and can alter the travel course so that such obstacles are avoided. They are not able, however, to detect potholes that constitute indentations in the road surface, or rough road surfaces, or mud or the like. For that reason, there is a danger that vehicles will run afoul of such obstacles because the travel course will not be altered to avoid them, rendering the vehicles unable to move.
A plurality of unmanned vehicles will be in operation at a work site. However, even if each of those plurality of unmanned vehicles carries an obstacle detector, there is no guarantee that every one of that plurality of vehicles will always be able to safely detect the same obstacle. More specifically, obstacle detectors generally make use of milliwave radar, laser radar, or visual sensors, wherewith the obstacle detection precision is affected by the S/N ratio.
Work sites such as mining sites tend to become dusty. Thus it happens that such dust constitutes noise when obstacles are being detected by obstacle detectors, making it very difficult to distinguish between those obstacles and the surrounding environment. It is thus possible that, depending on changes in the surrounding environment, even if an obstacle can be detected by the obstacle detector carried on one unmanned vehicle, that same obstacle might not be detectable with the obstacle detector carried on another unmanned vehicle. There is therefore a danger that the unmanned vehicle that could not detect the obstacle will run afoul of that obstacle.
In Japanese Patent Application Laid-Open No. 10-38586, an invention is described wherewith, instead of detecting obstacles ahead of vehicles by obstacle detectors, the obstacles are registered beforehand, and an alarm is issued when a vehicle approaches such a pre-registered obstacle to alert the operator to be careful.
In the invention described in this publication, the positions of obstacles to a snow removal vehicle are stored beforehand in a memory medium carried on board the snow removal vehicle. Provision is made so that, while the snow removal vehicle is in operation, the data in that memory medium are sequentially read out, and an alarm is issued when an obstacle stored in that memory medium is approached to alert the operator to be careful.
According to the invention described in the publication noted above, only those obstacles that have been pre-stored in the memory medium can be detected and avoided. Conversely, newly developed obstacles that have not been pre-stored in the memory medium cannot be detected or avoided.
To be sure, the problem of overlooking obstacles will not occur in applications in cases where fixed obstacles are detected, and no new ones develop, as in snow removal vehicle operations, with respect to ditches and road shoulders and the like that are covered with snow.
When
Jacques Jacques Louis
Komatsu Ltd.
Varndell & Varndell PLLC
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