Control device and method for guided travel of unmanned vehicle

Leveling operation can be effectively performed at a discharge site without increasing a cost of vehicles, and a running course can be easily generated in a short time and at a low-cost. Based on each of measured position data of a survey line 20 of a discharge site 21, a normal line Lc normal to the survey line 20 is obtained, a target discharge position 26′ is positioned at a prescribed distance away from the survey line 20 in an inward direction of the discharge site 21 based on the normal line Lc, and then data of a running course 27 in which a reference approach direction 31 to approach the target discharge position 26′ is a direction normal to the survey line 20 are generated.

TECHNICAL FIELD

The present invention relates to a control device and a method for a guided travel of an unmanned vehicle, more particularly to a preferred device and a method for applying to a case where, in a discharge site in a mine and the like, a guided travel of an unmanned vehicle is performed to a target discharge position and earth and sand is unloaded.

BACKGROUND ART

In a large mine, a guided travel system for an unmanned vehicle in which the unmanned vehicle such as unmanned off-road dump trucks is guided and travels has been widely used in order to reduce painful works, decrease the production cost, and save the fuel.

The above-mentioned unmanned vehicle has a position measuring device that measures its running position using GPS (Global Positioning System) and the like. Additionally, a monitor station that monitors plural unmanned vehicles obtains, by surveying a work site or teaching, position data on a running course through which the unmanned vehicle is to run, and stores the position data. After receiving the position data of the running course from the monitor station via a radio communication and the like, the unmanned vehicle measures its current position (and its direction) using a position measuring device that the vehicle has, compares the measured current position at the time of traveling with the running course in a sequence, and is steered and controlled so as to sequentially reach each position on the running course.

Here, as a method for obtaining the position data of the running course, for example, a teaching method in which a teaching vehicle actually travels and memorizes the travel path has been widely used.

In this case, the teaching vehicle actually runs so as to pass through target points where the unmanned vehicle has to reach. Then, the position data regarding a path from a running start point to a target point or a path from the running start point through the target point to a running end point is obtained. There is another method that only the position data of the target point is obtained by teaching, and the running course is generated through the obtained position data of the target point.

Japanese Patent Application Laid-open No. 2000-137522 discloses the following related arts 1 and 2.

As shown inFIG. 1, at a discharge site21in a mine, a discharging work is performed such that an unmanned vehicle13carries earth and sand, and discharges it. In this case, a teaching vehicle travels along a running course27to a target discharging position26′ located near a survey line20that functions as a boundary line of the discharge site21, whereby the position data of the running course27is obtained. As a result, the unmanned vehicle13can discharge the earth and sand outside the survey line20(to cliff) in the discharge site21after traveling along the taught running course27.

Since a discharge site21of a large scale mine or the like is wide, the number of target discharge positions26′ in the vicinity of a survey line20reaches several hundreds points along the survey line20. Thus, to obtain position data of running courses27for each of the large number of target discharge positions26′ by the teaching work as mentioned in the related art 1, the number of the teaching works using teaching vehicles becomes increase, requiring much more time and man-hour to generate running courses.

And, as shown inFIG. 2, the teaching vehicle40is traveled along the survey line20in the discharge site21, position data of plural target discharge positions26′ in the discharge site21are generated based on the obtained position data of the survey line20, and running courses27to reach each of the target discharge position are acquired through calculation process.

In a case where the related art 1 is employed, works at mines are performed as follows.

Specifically, for example, stripped earth and sand by a stripping work is loaded to an unmanned vehicle13. The unmanned vehicle13travels, by guiding, to the target discharge position26′ in the vicinity of the survey line20in the discharge site21. At the target discharge position26′, a carrier (body) performs a dumping operation toward a precipice, thereby falling off the earth and sand loaded on the carrier. The earth and sand, which does not fall off to the precipice and remains on the discharge site, in other words, pile26c, is pushed out by a bulldozer or other leveling vehicles, and the discharge site21is leveled. A discharge work such that a dump truck13discharges and falls off earth and sand from a high position to a precipice is called as a high-dump work.

On the other hand, in a case where the related art 2 is employed, works at mines are performed as follows.

Specifically, in a similar way to the above-mentioned case, stripped earth and sand by a stripping work is loaded to an unmanned vehicle13. The guided travel of the unmanned vehicle13is performed to the target discharge position26′ in the discharge site21. At the target discharge position26′, the carrier performs the dumping operation, and the earth and sand loaded on the carrier is unloaded. As a result, the earth and sand is piled on the discharge site as a highly piled up pile26cwithout falling off to the precipice. The bulldozer pushes out the highly piled up pile26c, and the discharge site21is leveled. The discharge work such that a dump truck13discharges the earth and sand within the discharge site21is called as a paddock discharge work.

Recently, the unmanned dump track has become larger, and the earth and sand loaded on the carrier (body) reaches 300 ton or heavier.

According to the related art 1, since the earth and sand is discharged by the high-dump work, in most cases, almost all the earth and sand is fallen off to the precipice, and relatively little earth and sand remains in the discharge site21. Consequently, as is often the case, leveling work by the bulldozer16is performed with relatively high operation efficiency.

However, according to the related art 2, since the earth and sand is discharged by the paddock discharge work, all the discharge earth and sand with more than300ton becomes the pile26cin the discharge site21. Therefore, it is difficult or may be impossible for an ordinary bulldozer16to push out the pile26c. And even if the bulldoze16can push out the pile26c, such piles26care piled up at plural target discharge positions26′ in the discharge site one after another. And, the amount of discharge work may exceed the capability of leveling work, resulting in decreased work efficiency. Furthermore, to enhance the capability of leveling work, it is necessary to use a larger bulldozer16, strengthen the pulling power, or increase the number of the bulldozers16, which may lead to increase in cost of the vehicles.

For this reason, considering only efficiency or cost of the leveling work, it is desirable to employ the related art 1 in which leveling work can be efficiently performed by a bulldozer with ordinary power. As mentioned above, the related art 1, however, requires time or cost for the teaching work on a running course, thus there remains a problem that time or cost required for generating the running course increases.

SUMMARY

The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a guided running control device and a method for an unmanned vehicle that can efficiently performs the leveling work at the discharge site without increasing the cost of the vehicle, and easily generate the running course in a short time and low-cost.

A first aspect of the present invention provides a control device for a guided travel of an unmanned vehicle, in which the unmanned vehicle is guided to travel along a running course so as to approach in a desired direction to a target discharge position as a target position where the unmanned vehicle performs a discharge operation at a discharge site, and to perform the discharge operation to discharge a load on the unmanned vehicle at the target discharge position, the control device comprising: survey line position measuring means for measuring each position of a survey line showing a boundary line of the discharge site; running course generation means for, after obtaining a line normal to the survey line based on each of the measured position data of the survey line in the discharge site, generating data of a running course, based on the normal line, in which the target discharge position is positioned at a prescribed distance away from the survey line and a direction of approaching the target discharge position is normal to the survey line; control means for guiding the vehicle to travel along the generated running course to the target discharge position, and operating the vehicle so as to discharge the load on the unmanned vehicle at the target discharge position after the unmanned vehicle reaches the target discharge position.

A second aspect of the present invention provides the control device according to the first aspect of the present invention, wherein the running course generation means; obtains each segment point on the survey line based on the measured position data on the survey line, obtains a line normal to each of the segment points, obtains a point on the normal line at a prescribed distance away from the segment point in an inward direction of the discharge site, obtains a line of which a line shape is corrected by applying a smoothing process to a line that is acquired by connecting each of the obtained points on each of the normal lines, and by setting to the target discharge position a position on a line normal to the line to which this smoothing process is applied, generates the data of the running course in which the direction of this normal line is a direction to approach the target discharge position.

A third aspect of the present invention provides the control device according to the first aspect of the present invention, wherein the running course generation means; obtains a line that a line shape is corrected by applying a smoothing process to a line that is acquired by connecting each of the measured positions on the survey line, obtains a line normal to the corrected line, sets to the target discharge position a position on the normal line, and generates the data of the running course in which a direction of the normal line is a direction to approach the target discharge position.

A fourth aspect of the present invention provides the control device according to the first aspect of the present invention, wherein a mound is formed along the survey line in the discharge site, the unmanned vehicle is provided with a sensor for detecting that a wheel of the unmanned vehicle reaches the mound formed along the survey line, and when the sensor detect that the wheel of the unmanned vehicle reaches the mound formed along the survey line before the wheel reaches the target discharge position, the unmanned vehicle is operated so as to discharge the load on the unmanned vehicle at the position that the sensor detects.

A fifth aspect of the present invention provides the control device according to the fourth aspect of the present invention, wherein the sensor detects a reduction of a speed or a travel distance of the unmanned vehicle, and when the reduction of the speed or the travel distance of the unmanned vehicle is detected by the sensor before a speed reduction instruction to stop the unmanned vehicle at the target discharge position is output, it is determined that the wheel of the unmanned vehicle reaches the mound formed along the survey line, and the unmanned vehicle is operated so as to discharge the load on the unmanned vehicle at the position that the sensor detects.

According to the first aspect of the present invention, as shown inFIGS. 11A and 11B, a line Lc normal to a survey line20is obtained based on each measured position data on the survey line20in a discharge site21. A target discharge position26′ is set to a position located prescribed distance from the survey line20on the normal line Lc in an inward of the discharge site21is. Then, data regarding a running course27in which a reference approach direction31for approaching the target discharge position26′ is normal to the survey line20are generated.

The second aspect of the present invention includes a restriction on generating means of the running course of the first aspect of the present invention. As shown inFIGS. 10A through 10C, each of segment points P1, P2, . . . is obtained on the survey line20on the basis of each of the measured position data on the survey line20. Lines La1, La2, . . . normal to each the segment points P1, P2, . . . are obtained. Points Q1, Q2, . . . located prescribed distance d from each of the segment points P1, P2, . . . on the normal lines La1, La2, . . . in an inward of the discharge site21are obtained for each of the normal lines La1, La2, . . . . By applying a smoothing process to a line Lb in which each of the points Q1, Q2, . . . on each of the normal lines La1, La2, . . . are connected, a line Lb′ of which a line shape is smoothed is obtained. Then, as shownFIGS. 11A and 11B, a position26on the normal line Lc normal to the line Lb′ to which the smoothing process is applied is the discharge position26. And then, data regarding a running course27in which a direction31of such normal line Lc is the direction31for approaching the discharge position26are generated.

The third aspect of the present invention includes a restriction on generating means of the running course of the first aspect of the present invention. As shown inFIGS. 12 and 11B, by applying the smoothing process to a line Ld in which each of the measured positions on the survey line20are connected, a line Ld′ of which a line shape is smoothed is obtained. A line Lc′ normal to the smoothed line Ld′ is obtained, and the discharge position26is located on the normal line Lc′. Then, data regarding a running course27in which a direction31of such normal line Lc′ is the direction31for approaching the discharge position26are generated.

The fourth aspect of the present invention further includes, in addition to the first aspect of the present invention, a mound detection section (sensor)30, and control for running by the mound detection section (sensor)30, as shown inFIGS. 4 and 5. As shown inFIG. 8, a vehicle13is provided with the mound detection section (sensor)30for detecting that a rear wheel13dof the unmanned vehicle13reaches a mound20C. When the sensor30detects that the rear wheel13dof the vehicle13reaches a mound20C′ formed along the survey line20before the vehicle13reaches the target discharge position26′, the unmanned vehicle13is operated so as to discharge the earth and sand loaded on the unmanned vehicle13at the position detected by the sensor.

The fifth aspect of the present invention includes a further restriction on the fourth aspect of the present invention. The mound detection section (sensor)30comprises a sensor that detects a reduction in speed and travel distance of the vehicle13. When the sensor30detects that the speed or travel distance of the unmanned vehicle13reduces before an instruction to slow down to stop the unmanned vehicle13is given, it is determined that the rear wheel13dof the unmanned vehicle13reaches the mount20C formed along the survey line20, and the unmanned vehicle13is operated so as to discharge the earth and sand loaded on the unmanned vehicle13at the position detected by the sensor.

According to the present invention, by automatic calculation process based on the data regarding each position on the survey line20measured through teaching, surveying and the like, plural target discharge positions26′ are obtained in the vicinity of and along the survey line20, and the reference approach directions31normal to the survey line20are determined. Based on the calculation result, running courses27to approach each of the target discharge position26′ in each of the reference approach directions31are automatically generated, and each vehicles13is guided to travel along each of the generated running courses27and discharge at each of the target discharge positions26′. Thus, it is possible that the vehicle13approaches in the vicinity of the survey line with the reference discharge position31, whereby discharging can be performed in the most efficient manner, and that the vehicle13discharges the earth and sand outside the survey line20(or in the vicinity of the survey line20) using the high-dump work in a secure and correct manner. As a result, almost all of the earth and sand can be discharged down to the precipice outside the survey line20, the earth and sand that remains in the discharge site21can be reduced as minimum as possible. Consequently, leveling work can be efficiently performed by ordinary bulldozers16, and the cost of efficient leveling work, vehicles and the like can be dramatically reduced.

Additionally, unlike the related arts, when generating the plural running courses27, it is not necessary to differently teach the running courses27to each of the target positions (discharge positions). Each of the running courses27is automatically generated after measuring each of the positions along the survey line20in the discharge range20L. Therefore, time and cost for carrying work by the vehicle13, preparation work (teaching or surveying) performed before the leveling work by the vehicle16can be reduced.

As mentioned above, according to an aspect of the present invention, leveling work at the discharge site21can be efficiently performed without raising the cost of vehicles, and the running courses27can be easily generated in a short time and at low cost.

Additionally, according to the fourth and fifth aspect of the present invention, the earth and sand can be discharged outside the survey line20in a safety and secure manner without derail and the like of vehicle13. Thus, it is possible to safely perform the guided travel of the vehicle13, and operate the discharge work safely.

DETAILED DESCRIPTION

Hereinbelow, an exemplary embodiment of a control device for a guided travel of a vehicle according to the present invention will be described in detail with reference to the attached drawings.

FIG. 1shows an appearance of a work site of the exemplary embodiment. In this exemplary embodiment, a case is assumed where the guided travel of the unmanned vehicle13such as an off-road dump truck, which loads earth and sand, is performed along a running course27to a target discharge position26′ in a discharge site21in a large scale mine site, and the earth and sand is discharged at the target discharge position26′.

FIG. 3is a conceptual diagram of the discharge site21viewing from above.

In this exemplary embodiment, a case is assumed where a discharge range20L (end points:20A,20B) is determined from a survey line20that is a boundary line of the discharge site21, a guided travel of vehicles13is performed along running courses27to each of the target discharge position26′ in the discharge range20L, the vehicles13performs dumping operations at each of the target discharge positions26′, and the earth and sand is discharged outside or in the vicinity of the survey line20.

Hereinbelow, a description will be made using an unmanned off-road dump truck13as an example of the vehicle. The vehicle13is a front wheel driving vehicle having a driver's cabin (cab)13aat a front portion thereon, a rear deck (vessel, body) at a rear portion thereon, and front wheels13cand rear wheels13d. The vehicle13approaches the target discharge position26′ in a state of reverse traveling, in other words, in the state that the rear wheels13dare positioned to a front portion against a traveling direction, in a reference approach direction31(reference discharge position) described later, in other words, in the approach direction31normal to the survey line20.

FIG. 4shows a block diagram of an exemplary embodiment of a vehicle monitoring system.

In a work site, a monitor station12for managing and monitoring a number of vehicles13is provided. The monitor station12has a processing section1, a target position generation section2, a data input section3, and a communication section4. The vehicle13has a running course generation section5, a communication section6, processing section7, a position measuring section8, a running mechanism section9, a steering mechanism section10, a running course storing section11, and a mound detection section30.

The position measuring section8of the vehicle13measures a current position of the vehicle. As means for measuring the position, for example, a tire revolution number sensor and a gyroscope provided to the vehicle13are used. Then, the position of the vehicle is measured based on output signals from the tire revolution number sensor and the gyroscope. Additionally, the position of the vehicle may be measure by GPS.

The position data measured by the vehicle13is processed by the processing section7, and is sent to the monitor station12via the communication section6.

The communication section4in the monitor station12receives the position data sent by plural vehicles13. The processing section1generates instruction data that include instructions of the starting, the stopping, and the like, for the vehicle13based on positional relationships between each of the plural vehicles13, and the communication section4sends those instruction data to the vehicle13.

The communication section6in the vehicle receives the instruction data sent by the monitor station12.

And the processing section7in the vehicle13generates a running instruction and a steering instruction to travel and steer the vehicle in accordance with the received instruction data. The running instruction and the steering instruction are output to a running mechanism section9and a steering mechanism, respectively. As a result, the vehicle13travels and steers in accordance with the instruction data sent by the monitor station12.

To the data input section3in the monitor station12, topography data of the discharge site21obtained by teaching or surveying are input. While a discharge range20L is determined in the survey line, each position data on the survey line20in the discharge site21are input. Vehicle data of the vehicle13are also input.

The data that is input into the data input section3in the monitor station12are processed by the processing section1. The target position generation section2generates positional data regarding plural discharge positions26along the survey line20, and data regarding the reference approach directions31(reference discharge position) to approach each of the discharge positions26.

While selecting a next discharge position26from plural discharge positions26generated by the target position generation section2, the processing section1selects a next vehicle13that travels to the next discharge position26. Through the communication section4, a position of the selected discharge position26and reference approach direction data are sent to the selected vehicle13.

The communication section6of the vehicle receives the data of a position of the discharge position26and the reference approach direction sent from the monitor station12.

The received data of the position of the discharge position26and the reference approach direction are processed in the processing section7, and the running course generation section5generates a running course27to approach the discharge position26, which is regarded as a target discharge position26′, in the reference approach direction31corresponding to the target discharge position26′. The position data of the generated running course27are stored in the running course storing section11.

The processing section7generates the running instruction and the steering instruction in which the vehicle13follows each of the positions on the running course27by comparing the current vehicle position measured by the position measuring section8with each of the positions on the running course27stored in the running course storing section11. The running and the steering instructions are output to the running mechanism section9and the steering mechanism section10, respectively. Consequently, the vehicle13is guided to travel along the running course27, and reaches the target discharge position26′ in the reference approach direction31.

FIG. 8is a sectional view taken along the line a-a ofFIG. 3, in other words, a vertical sectional view take along the survey line20, showing an appearance that the vehicle13approaches the target discharge position26′ in a reverse travel.

A mound20C is formed along the survey line20in the discharge site21. This mound20C is higher than the ground level of the discharge site21.

The vehicle13has the mound detection section (sensor)30(FIG. 4) for detecting that the rear wheel13dof the vehicle13reaches the mound20C. Specifically, the mound detection section30comprises a sensor for detecting the reduction of the speed or the travel distance of the vehicle13. When the rear wheel13dreaches the mound20C, a load is activated to the rear wheel13dand the speed is reduced. Hereinbelow, a description will be made by referring to a center position (contact point) of the rear wheel13dof the vehicle13as the position of the vehicle13. In the exemplary embodiment, the travel of the vehicle13is controlled such that the center position of the rear wheel of the vehicle13stops at the target discharge position26′.

In a configuration inFIG. 4, although the running course generation section5is provided in the vehicle13, the running course generation sections, as shown inFIG. 5, may be provided to the monitor station12.

In a configuration inFIG. 5, the discharge positions26along the survey line20in the discharge site21and the reference approach direction data are generated by the target generation section2in the monitor station12. The running course generation section5generates each of the running courses27to approach each of the target discharge positions26′ for each of the discharge positions26in each of the reference approach directions31. While selecting the next running course27to be traveled from each of the running courses generated by the running course generation section5, the processing section1selects the next vehicle13to travel. Through the communication section4, the position data of the selected running course27are sent to the selected vehicle13.

The communication section6in the vehicle13receives the position data of the selected running course27sent by the monitor station12. The received position data of the running course27are stored in the running course storing section11.

Next, with reference to the flow chart shown inFIG. 9, the generation procedures of the discharge position26and the reference approach direction31at the discharge position26that are generated in the target position generation section2inFIGS. 4 and 5, and the generation procedure of the running course generated in the running course generation section5will be described. In the flow chart shown inFIG. 9, the description will be made based on the premise of the configuration shown inFIG. 5. In other words, a case is assumed where, while the monitor station12generates the discharge position26and the reference approach direction31, the running course27is generated.

First, a path of the running course27will be described.

As shown inFIGS. 1 and 3, the discharge site21is a region surrounded by the survey line20. In the discharge site21, an entrance21afor the vehicle13is provided. The entrance21ais placed between a common running course region14and the discharge site21.

A discharge range20L is a range in the survey line20where the discharge is operated. In the discharge range20L, plural discharge positions26are placed in regular intervals along the survey line20. The intervals of the discharge position26are set at distances where leveling operation can be easily performed by a bulldozer16. The reason that plural discharge positions26are placed at regular intervals along the survey line20is to prevent the collapse of the edge of the ground and to easily form the mound20C (FIG. 8) along the survey line20by evenly piling the earth and sand in regular intervals along the survey line20. The reason for determining the discharge range20L is because the whole survey line is not necessarily dischargeable region, for example, there exists a sheer cliff like a wall in a part of the survey line. The efficiency of the leveling operation using the bulldozer16can be improved by setting the survey line to have plural discharge ranges.

The vehicle13starts to travel from the travel starting point, travels in a direction of arrow A on the common running course region14, and reaches the entrance21aof the discharge site21. Passing through the entrance21a, the vehicle13enters into the discharge site21. Then, the vehicle13performs a switchback movement in the discharge site21. In other words, after advancing toward the arrow B direction, the vehicle13travels backward in a direction of arrow C, in principle, along the reference discharge direction13. Then, the vehicle stops at the target discharge position26′ and the earth and sand is discharged. In other words, a rear deck (vessel, body)13bof the dump truck13is tilted and the earth and sand on the rear deck13bis discharged at the target discharge position26′. After completing the discharge operation, the vehicle13advances toward the arrow D, leaves the discharge site21from the entrance21a, and enters into the common running course region14. Then, the vehicle13travels in a direction of arrow E on the common running course region14, and reaches the travel ending point.

Here, while the discharge site21(area inside of and surrounded by the survey line20) and the common running course region14are an area possible to run where the vehicle13can run, an area outside of the area possible to run is an area impossible to run where the vehicle13cannot run. For example, the outside of the survey line20of the discharge site21is an area where the vehicle13cannot run because of its topographical reasons such as existence of a cliff and wall.

Here, in step101ofFIG. 9, the topographical data of the discharge site21, in other words, the data that show positions and shapes of the discharge site21such as each positional data of the entrance21aof the discharge site21are input through the data input section3having keyboards and the like (step101).

Next, in the survey line20of the discharge site21, positional data that show each position located on the survey line20are input after positions of each of the end points20A,20B of the discharge range20L are designated (step102).

Each of the positional data on the survey line20, and the end points20A,20B of the discharge range20L are obtained through survey. Or these data may be obtained through teaching.

FIG. 6shows a configuration of designating the discharge range20L by a manned vehicle (vehicle for teaching)40, and sending the designated data to the monitor station12.

A position measuring section48in the manned vehicle40measures the positions of the manned vehicle40. As shown inFIG. 3, a display screen of the display section42shows the position, the shape and the appearance that the manned vehicle40travels in the discharge site21. The topographical data of the discharge site21that are input, in step101, into the monitor station21are sent to the manned vehicle40. The manned vehicle40generates the position and the shape of the discharge site21based on the sent topographical data. And then, the display screen of the display section42displays the position and the shape of the discharge site21.

An operator of the manned vehicle40actually travels the vehicle40to reach the end point20A that is one end of the discharge range20L for discharging the earth and sand. After confirming on the display screen of the display section42that the vehicle40reaches the desired end point20A, the operator operates the input section41to input a command of “end point”. As a result, at a time of the input, the position measured by the position measuring section48is designated as position data that show the end point20A, and the positional data showing this end point20A is stored in the processing section47. Additionally, the operator of the vehicle40travels the vehicle40, along the survey line20, to the end point20B that is other end of the discharge range20L. Through this operation, the data showing each position on the survey line20one by one are measured by the position measuring section48, and stored in the processing section47. When the vehicle40reaches the end point20B that is the other end point of the discharge range20L for discharging the earth and sand, the operator operates the input section41to input a command of “end point” after confirming that the vehicle40reaches the desired end point20B. As a result, at a time of input, the position measured by the position measuring section48is designated as the positional data showing the end point20B, and the positional data showing this end point20B are stored in the processing section47.

The data that are stored in the processing section47and show each of the positions on the survey line20(data showing each of the positions on the discharge range20L) are sent from the communication section46to the communication section4in the monitor station12. The above-mentioned positional data are received by the communication section4of the monitor station12, and stored in the processing section1.

FIG. 7shows a configuration in a case when the data showing each of the positions on the survey line20(data showing each of the positions on the discharge range20L) are obtained by the monitor station12.

In this case, the survey is conducted in advance, and the data showing each of the positions on the survey line20are obtained. Each of the positional data on the survey line20that is obtained through surveying is input to the data input section3in the monitor station12. On a display screen of the display section52, positions and shapes of the survey line20in the discharge site21is displayed based on the topographical data of the discharge site that are input in step101and each of the positional data obtained through surveying. An operator in the monitor station performs input operation on the display screen of the display section52to designate the end points20A,20B of the discharge range20L for discharging the earth and sand. Through this operation, the positional data showing each of the positions on the discharge range20L are stored in the processing section1.

Next, discharge positions26and reference approach direction31(reference discharge position) at each of the discharge positions26are calculated based on the data showing each of the positions on the survey line20(data showing each of the positions on the discharge range20L) obtained as mentioned above.

FIGS. 10 and 11show diagrams describing a calculation process for obtaining the discharge positions26and the reference approach direction31(reference discharge position) at each of the discharge positions26. This calculation process is carried out in the target position generation section2.

In this exemplary embodiment, each segment point P1, P2, . . . is obtained on the survey line20on the basis of each of the measured position data on the survey line20. Lines La1, La2, . . . normal to the survey line20at each of the segment points P1, P2, . . . are obtained. Points Q1, Q2, . . . located in a prescribed distance d from each of the segment points P1, P2, . . . on each of the normal lines La1, La2, . . . in an inward of the discharge site21are obtained for each of the normal lines La1, La2. . . . By applying a smoothing process to a line Lb that is obtained by connecting each of the points Q1, Q2, . . . on each of the normal lines La1, La2, . . . , a line Lb′ of which a line shape is smoothed is obtained (FIGS. 10A,10B and10C). Then, a position26on the normal line Lc normal to the line Lb′ to which the smoothing process is applied is the discharge position26, and a direction31along the normal line Lc is set to a direction31to approach the discharge position26(FIGS. 11A and 11B). Hereinbelow, the calculation process will be described in order.

In the exemplary embodiment, as shown inFIG. 8, a start point51of a dischargeable section50is set at a position that is located in a prescribed distance d away from the survey line20in an inward of the discharge site21. The discharge position26is set at a position that is located a prescribed distance away from the start point51of the dischargeable section50in an inward of the survey line20. The dischargeable section50is a section between the start point51and the discharge position26. The vehicle13stops and can discharge in this dischargeable section50. The discharge position26is set in a position where the vehicle13can safely discharge the earth and sand loaded on the rear deck13boutside the discharge site21without derailing and the like at the time when the rear wheel13dof the vehicle13is positioned at the discharge position26.

As shown inFIG. 10A, each of the segment points P1, P2, . . . is obtained by minutely segmenting the survey line20into plural points based on each of the positional data on the survey line20.

Next, as shown inFIG. 10B, by obtaining each of the lines La1, La2, . . . normal to each of the segment points P1, P2, . . . , each of the points Q1, Q2, . . . on each of the normal lines La1, La2, . . . that is located in the prescribed distance d away from each of the segment points P1, P2, . . . in an inward of the discharge site21is obtained. Here, the distance d is a distance that sets the start point51of the dischargeable section50. This distance d is set based on the radius of the rear wheel13dof the vehicle13and the like (vehicle data).

Next, as shown inFIG. 10C, the line Lb′ of which line shape is corrected is obtained by performing a smoothing process to the line Lb that is obtained by connecting each of the points Q1, Q2, . . . on each of the normal lines La1, La2, . . . . This smoothing process is performed through the filter process.

Each of the points on each of the lines Lb′ obtained through the process mentioned above is the start point51of the dischargeable section50.

Next, as shown inFIG. 11A, by minutely segmenting the line Lb′ into plural points R1, R2, . . . and selecting segment points from each of the segment points R1, R2, . . . in every prescribed intervals, each of the selected segment points in every prescribed intervals is set to each of the start points51of the dischargeable section50.

Next, as shown inFIG. 11A, segment points Rn, Rm both of which are located next to the start point51of the dischargeable section50along the line Lb are selected. The normal line Lc is a line normal to a line segment that is formed by connecting the segment points Rn, Rm. The direction of this normal line Lc is set to the reference approach direction31that the vehicle31approaches the discharge position26.

Next, as shownFIG. 11A, based on the position of the start point51obtained through above-mentioned process, the direction31of the normal line Lc and the vehicle data, the position of the discharge position26is set at a position located on the normal line Lc and in the prescribed distance corresponding to a distance of the dischargeable section50starting from the start point51. This calculation process is performed for each of the start points51on the line Lb′. As mentioned above, each of the discharge points26is obtained along the discharge range20L, and each of the reference approach directions31at each of the discharge directions26is calculated. (step103)

In the above-mentioned description, the calculation process for obtaining the discharge positions26and the reference approach directions31has been described only as one example. However, the present invention is not intended to be limited to this calculation process.

For example, as shown inFIG. 12, by obtaining a line Ld′ of which line shape is corrected through applying the smoothing process to a line Ld that is formed by connecting each of the measured positions on the survey line20so as to acquire a normal line Lc′ that is normal to the line Ld′ to which the smoothing process is applied, the discharge position26may be set on this normal line Lc′, and the direction31of this normal Lc′ may be set to the reference approach direction31for the reference to approach the discharge position26. In this case, each of the discharge positions26is obtained for each of the normal lines Lc′, each of the reference approach directions31for approaching each of the discharge positions26, whereby each of the discharge positions26can be obtained along the discharge range20L, and each of the reference approach directions31for approaching each of the discharge positions can be obtained.

Next, as shown inFIG. 11B, based on the data of the discharge position26and the reference approach direction31obtained in step103, by setting the discharge position26as the target position (target discharge position)26′, data for a running course in which the vehicle13approaches this target discharge position26′ in the reference approach direction31in a reverse travel is generated. And the running courses27are generated for each of the target discharge positions26′.

As mentioned above, based on each of the measured position data of the survey line20in the discharge site21, the normal lines Lc (normal lines Lc′ in a case ofFIG. 12) to the survey line20are obtained. Based on this normal lines Lc (Lc′), the target discharge position26′ is set to a position located a prescribed distance away from the survey line20in an inward of the discharge site21. And then, the data for the running courses27in which the reference approach direction31to approach the target discharge position26′ is normal to the survey line are generated (step104).

Note that, even when the running courses27vary according to each of the target discharge positions26′, the running course data in the common running course region14in the running course27is common data. Therefore, each of the running courses27may be efficiently generated by producing only course data within the discharge site21and combining the produced course data with the common course data.

When the running courses27are generated as mentioned above, a process for guiding the vehicle to travel along the running course27is performed in the following steps105and106. In this case, as shown in a loop100A inFIG. 9, the running courses27may be generated every time the vehicle is guided to travel. Or, as shown in a loop100B, after generating all the running courses27corresponding to each of the discharge positions26within the discharge range20L (step104), the vehicles13may be guided to travel along each of the running courses27one by one (steps105and106).

As shown in the loop100A inFIG. 9, in a case where the running course27is generated every time the vehicle13is guided to travel, in a configuration ofFIG. 5, the running course generation section5in the monitor station12generates the next running course2to travel, and the positional data of the generated running course27are sent to the next vehicle13that is to travel. The vehicle13receives the sent positional data of the running course27, and the positional data is stored in the running course storing section11. In a case of the configuration ofFIG. 4, the target position generation section2in the monitor station12obtains the next discharge position26for discharging the earth and sand, and the data of the reference approach direction to approach the discharge position26(step103). And, the discharge position26and the data of the reference approach direction are sent to the next vehicle that is to travel, and the running course generation section5in the vehicle13generates the running course27that passes through the discharge position26based on the received discharge position26and data of the reference approach direction (step104). And the positional data of the generated running course27are stored in the running course storing section11.

As shown in the loop100B inFIG. 9, in a case where, after all the running courses27corresponding to each of the discharge positions26within the discharge range20L are generated, the vehicles13are guided to travel along each of the running courses27one by one, in a configuration ofFIG. 5, the monitor station12selects the next running course27that is to be traveled from all the generated running courses27, and the optional data of the selected running course27are sent to the next vehicle13that is to travel. In this vehicle13, the positional data of the sent running course13are stored in the running course storing section11.

As mentioned above, in a either case of the loop100A, the loop100B, the configuration ofFIG. 5or the configuration ofFIG. 4, by sending the data regarding the running course27from the monitor station12, the running course monitoring section11in the vehicle13stores the positional data of the running course27(step105).

At the time of running, the positional data of the running course27stored in the running course storing section11are read out. The processing section7compares the current position of the vehicle measured by the position measuring section8with each of the position of the running course27read out from the running course storing section11, and generates a running and a steering instructions in which the vehicle13follows each of the sequence of the positions on the running course27. The running and the steering instructions are output to the running mechanism section9and the steering mechanism section10, respectively. Consequently, as shown inFIGS. 3 and 11B, the vehicle13is guided to travel along the running course27and reaches the target discharge position26′ in the reference approach direction (reference discharge position)31.

Specifically, the vehicle13starts to travel from the travel starting point, travels in a direction of arrow A on the common running course region14, and reaches the entrance21aof the discharge site21. Passing through the entrance21a, the vehicle enters into the discharge site21. Then, the vehicle13performs a switchback movement in the discharge site21. In other words, after advancing toward the arrow B direction, the vehicle13travels backward in a direction of arrow C. And, as shown inFIG. 8, an instruction to reduce the speed of and stop the vehicle13when the center of the rear wheel13dof the vehicle13reaches the target discharge position26′ is output, and a speed of the vehicle is reduce to stop. After the vehicle13stops, the discharge operation is performed. In other words, the rear deck13bof the dump truck13is tilted to discharge the earth and sand loaded in the rear deck13b. However, even when the vehicle does not reach the target discharge position26′, the vehicle13may stop to perform the discharge operation if the vehicle is in the range of the dischargeable section50.

The running mechanism section9controls the running of the vehicle13by adjusting the brake, engine revolution, and the like on the basis of the detected signal from the mound detection section30.

As shown by the broken line20C′ inFIG. 8, the mound20C′ may be located before the target discharge position26′ and inside of the discharge site21. In this case, if the center of the rear wheel13dis moved to reach the calculated target discharge position26′, there is a possibility of detail and the like of the vehicle13because the position locates, in fact, outside of the survey line20. Therefore, regarding the dischargeable section50as “a possible section where the mound20C is actually located”, the speed reduction instruction is output at the time of detecting the mound20C to reduce and stop the vehicle13when the mound20C is detected in this dischargeable section50.

The detection signal of the mound detection section30is output, as an effective signal, to the running mechanism section9when the center position of the rear wheel13dis located in the dischargeable section50. When the rear wheel13dreaches the mound20C, a load is activated to the rear wheel13dand the speed is reduced. When the detection signal that the speed of the vehicle13is reduced is input to the running mechanism section9, the running mechanism section9outputs the speed reduction instruction to stop the vehicle13, even before the speed reduction instruction to stop the vehicle13at the target discharge position26′ is output. Accordingly, the vehicle13stops at a position where the center of the rear wheel13dis located before the target discharge position26′ without climbing over the mound20C′. And then, the discharge operation is performed after the vehicle13stops. As a result, it is possible to safely and securely discharge the earth and sand outside of the survey line20without derailing and the like of the vehicle13. Note that when the mound detection section30does not detect the mound20C, in other words, when the speed or travel distance of the vehicle13is not reduced by the mound20C, the running mechanism section9outputs the speed reduction instruction to stop the vehicle13at the target discharge position26′, and the vehicle13is stopped in a state that the center of the rear wheel13dis matched with the target discharge position26′.

Note that, when the center position of the rear wheel13dis located outside of the dischargeable section50(before the dischargeable section50), the detection signal from the mound detection section30is not input to the running mechanism section9as the effective signal. Thus, a situation that the vehicle13unnecessarily stops to discharge the earth and sand far before the survey line20by detecting the small gaps and the like on the ground in the discharge site21can be avoided.

After completing the discharge operation, the vehicle13advances in a direction of arrow D, leaves the discharge site21from the entrance21aof the discharge site, and enters into the common running course region14. Then, the vehicle13travels in a direction of arrow E on the common running course region14, and reaches the travel ending point.

As mentioned above, according to the exemplary embodiment, the vehicle13can be safely guided to travel, and safely perform the discharge operation.

According to the exemplary embodiment, by automatic calculation process based on the data regarding each position on the survey line20measured through teaching, surveying and the like, plural target discharge positions26′ are obtained in the vicinity of and along the survey line20, and the reference approach directions31normal to the survey line20are determined. Based on the calculation result, running courses27to approach the target discharge position26′ in the reference approach direction31are automatically generated, and vehicles13are guided to travel along the generated running courses27and discharge at the target discharge positions26′. Thus, it is possible that the vehicle13approaches in the vicinity of the survey line with the reference discharge position31, whereby discharging can be performed in the most efficient manner, and discharges the earth and sand outside the survey line20(or in the vicinity of the survey line20) using the high-dump work in a secure and correct manner. As a result, almost all of the earth and sand can be discharged down to the precipice outside the survey line20, the earth and sand that remains in the discharge site21can be reduced as minimum as possible. Consequently, leveling work can be efficiently performed by ordinary bulldozers16, and the cost of efficient leveling work, vehicles and the like can be dramatically reduced.

Additionally, unlike the related arts, when generating the plural running courses27, it is not necessary to differently perform teaching operation for the running courses27each of which has different target positions (discharge positions). Each of the running courses27is automatically generated after measuring each of the positions along the survey line20in the discharge range20L. Therefore, time and cost for carrying work by the vehicle13, preparation work (teaching or surveying) performed before the leveling work by the vehicle16can be reduced.

As mentioned above, according to the exemplary embodiment, leveling work at the discharge site21can be efficiently performed without raising the cost of vehicles, and the running courses27can be easily generated in a short time and at low cost.

Note that, in the exemplary embodiment, a description has been made by assuming the case where the vehicle13carries the earth and sand, and discharges them at the discharge site21. However, the description is not intended to limit the load that the vehicle13carries and discharges to “the earth and sand”, and the types of loads that the vehicle13carries and discharges are not limited to the earth and sand.