Patent Description:
Dump trucks, which transport earth and sand and ores while traveling on a transportation path, operate in a strip mine or the like. Since such dump trucks generally have a large weight and many transportation paths are unpaved, ruts tend to be generated on the travel trajectories of the dump trucks. The presence of a rut has a negative influence, such as increase in road surface resistance, reduction of body stability, or the like, and thus a maintenance vehicle, such as a grader, usually performs ground leveling for the maintenance of the transportation path. Unfortunately, such ground leveling work on the transportation path disturbs traveling of the dump trucks, resulting in a low transportation efficiency. For this reason, it is desirable that generation of ruts be suppressed as much as possible when the dump trucks travel. In addition, in a known autonomous travel system for performing transporting work using dump trucks that travel autonomously (hereinafter referred to as "unmanned vehicles") without an operator on board, deeper ruts tend to be generated when a plurality of unmanned vehicles travels on the same track. Thus, it is more important to solve the foregoing problem.

As conventional techniques, for example Patent Literature <NUM> below or the like describes a method that generates in advance a plurality of target travel paths, along which an unmanned vehicle travels toward loading work points of an excavator in a loading place of a mine, and selects a travel path from the plurality of target travel paths. Meanwhile, for example Patent Literature <NUM> below or the like describes a method that controls, upon detecting a rut, a passage position of a vehicle traveling automatically on a predetermined travel path such that its wheels pass on a step of the rut. Patent Literature <NUM> shows an autonomous driving system, in which an in-vehicle device is mounted in the autonomous vehicle, which autonomously travels on a road. The in-vehicle device performs autonomous driving so that a line traveled by the autonomous vehicle is displaced an offset value transversely from the transverse center of the road. Patent Literature <NUM> shows a method of navigating an autonomous vehicle having at least a first type of environment perception sensor, the method comprising: receiving a plurality of sensor performance reports including a road segment identifier and sensor range data for the first type of environment perception sensor on the identified road segment; for each of a plurality of road segments, using the received sensor performance reports to determine at least a first average sensor range for the first type of sensor; selecting a route for the autonomous vehicle based at least in part on the first average sensor range for at least one road segment on the route; and causing the autonomous vehicle to follow the selected route.

In the method described in the above Patent Literature <NUM>, generation of ruts is suppressed by displacing a travel track of an individual vehicle for dispersion. Meanwhile, in the method described in the above Patent Literature <NUM>, the influence of a generated rut is reduced by detecting a rut and displacing a travel track of a vehicle when traveling so as to flatten a step of the rut. Both of these techniques are used for suppressing the generation of ruts when one vehicle operates. However, as described in the above Patent Literature <NUM>, <NUM>, giving a travel instruction individually to the plurality of vehicles operating in a worksite, such as a mine, may increase a computation load and make a computation process more complicated, for example. In addition, on a transportation path, when unmanned vehicles traveling in opposite lanes displace their respective tracks toward the opposite lane, the vehicles may come close to each other when passing by the on-coming vehicle, thus increasing a collision risk. For this reason, on the transportation path, it is necessary for a vehicle to displace its track with a proper distance from a vehicle in the opposite lane.

The present invention has been made in view of the foregoing and provides an autonomous travel system capable of effectively suppressing generation of ruts. It is a further object of the present invention to provide an autonomous travel system including unmanned vehicles that travel on a transportation path constituted of opposite lanes, which is capable of suppressing generation of ruts while preventing proximity to an on-coming vehicle.

In order to solve the above problem, the invention is set out in the appended set of claims.

According to the present invention, since a plurality of vehicles operating in a worksite displaces target tracks based on common offset information, it is possible to effectively suppress generation of ruts. In addition, since the target tracks are displaced based on the common offset information when a plurality of unmanned vehicles travels on a transportation path including opposite lanes, it is possible to disperse travel tracks and suppress generation of ruts while maintaining a safe distance between the vehicles when passing each other.

It should be noted that other problems, configurations, and advantageous effects will become apparent from the following description of embodiments.

The invention is set forth in the independent claim <NUM> and in the dependent claims <NUM> to <NUM>.

Parts having the same function are denoted by the same or associated reference numerals throughout the drawings for illustrating the embodiments, and repeated description thereof will be omitted. Further, in the following embodiments, description of the same or similar part will not be repeated in principle unless otherwise particularly needed.

<FIG> is a diagram illustrating a schematic configuration of an autonomous travel system <NUM> according to a first embodiment. The autonomous travel system <NUM> illustrated in <FIG> includes at least one unmanned vehicle (e.g., dump truck) <NUM> for transporting loads, such as earth and sand and ores loaded from an excavator <NUM> that performs digging and loading work in a worksite, such as a strip mine, and a wireless network <NUM> that allows the unmanned vehicles <NUM> to be communicably connected to each other. In the worksite in which the unmanned vehicle <NUM> travels, there is also a manned vehicle (e.g., a grader) <NUM> used for maintenance of a transportation path or the like. It should be noted that in <FIG>, each unmanned vehicle <NUM> that can autonomously travel is denoted by <NUM>-<NUM>, <NUM>-<NUM>, and the like. In the autonomous travel system <NUM> of the present embodiment, each unmanned vehicle <NUM> refers to map information constituted of nodes (not illustrated), each defined beforehand by coordinates, representing a travel path <NUM>, and travels such that the coordinates of the own-vehicle position approach the coordinates of the nodes, so as to autonomously travel while tracking the travel path <NUM>.

<FIG> is a block diagram of the unmanned vehicle <NUM> in the autonomous travel system <NUM> according to the first embodiment. The autonomous travel system <NUM> includes a plurality of unmanned vehicles <NUM> having the identical configuration.

The unmanned vehicle <NUM> includes, as hardware configurations, an in-vehicle control device <NUM>, a storage device <NUM>, a wireless communication device <NUM>, a travel drive device <NUM>, a position sensor <NUM>, a speed sensor <NUM>, a steering angle sensor <NUM>, a load sensor <NUM>, and a time management device <NUM>.

The travel drive device <NUM> is for allowing (driving) the unmanned vehicle <NUM> (or the body thereof) to autonomously travel, and includes a travel motor for allowing the unmanned vehicle <NUM> to travel, a brake, and a steering motor for changing a steering angle of the unmanned vehicle <NUM>.

The position sensor <NUM> is for acquiring a position (i.e., own position) of the unmanned vehicle <NUM> and may be, for example, a global positioning system (GPS) or the like. Alternatively, the position sensor <NUM> may be a combination of a GPS apparatus and an inertial measurement unit (IMU) for calculating a position, or a system for specifying a position using radio waves from a base station installed on the ground.

The speed sensor <NUM> is for acquiring a speed of the unmanned vehicle <NUM> and may be, for example, a GPS apparatus or a wheel speed sensor.

The steering angle sensor <NUM> is for acquiring a steering angle of the unmanned vehicle <NUM> and may be, for example, an encoder or the like attached to a steering mechanism of the body.

The load sensor <NUM> is for acquiring a load condition of the unmanned vehicle <NUM> and may be, for example, a sensor for measuring a weight, or the like. Alternatively, the load sensor <NUM> may be a system including a sensor for measuring a suspension pressure of the body to estimate a load weight based on the measured pressure.

The time management device <NUM> is for synchronizing timings of updating offset information (described later), and is adapted to hold a time of the own vehicle received from an offset information distribution unit <NUM> when the offset information distribution unit <NUM> detects a change in the state of the body, such as when each unmanned vehicle <NUM> performs dumping or the like, and then notify the time to another vehicle via the wireless communication device <NUM>. In addition, when receiving a time from another vehicle via the wireless communication device <NUM>, the time management device <NUM> matches the time of the own vehicle held in the time management device <NUM> to the received time.

The in-vehicle control device <NUM> includes a CPU (central processing unit), RAM (random access memory), and ROM (read only memory), which individually perform calculation of a program, perform reading and writing information from and to a work area, and temporarily store the program, to control the operation of the unmanned vehicle <NUM>. In the autonomous travel system <NUM> of the present embodiment, the in-vehicle control device <NUM> outputs to the travel drive device <NUM> a travel instruction to control traveling of the body so that the unmanned vehicle <NUM> autonomously travels while tracking the travel path <NUM>.

The storage device <NUM> is an information readable/writable non-volatile storage medium, and stores an operating system (OS), various control programs, application programs, databases, and the like. In the autonomous travel system <NUM> of the present embodiment, the storage device <NUM> stores map information <NUM> representing the travel path <NUM>.

The wireless communication device <NUM> is radio equipment for connection to the wireless network <NUM>, capable of communicating information with the outside.

The in-vehicle control device <NUM> of the unmanned vehicle <NUM> includes, as functional blocks, an autonomous travel control unit <NUM>, an offset amount determination unit <NUM>, and an offset information distribution unit <NUM>. The storage device <NUM> includes the map information <NUM>.

<FIG> illustrates an example of data stored as the map information <NUM>. The map information <NUM> is information on a series of nodes representing the travel path <NUM> of the own vehicle. In the map information <NUM>, each node is given a node ID, coordinates indicating a position in a mine, a target speed of the unmanned vehicle <NUM>, and an offset factor for determining an offset amount of each node (described later). The map information <NUM> is provided in advance with information corresponding to sections required for the unmanned vehicle <NUM> to travel, and for example, an external control station or the like may set, for each unmanned vehicle <NUM>, nodes of exclusive travel sections that prevent the unmanned vehicle <NUM> from interfering with another unmanned vehicle <NUM>, and the nodes received via the wireless communication device <NUM> may be stored as needed. Alternatively, the map information <NUM> may hold in advance all of the series of nodes of a path along which the unmanned vehicle <NUM> should travel. In this case, in order to avoid interference with another vehicle, the unmanned vehicle <NUM> may periodically receive the position of the other vehicle via the wireless communication device <NUM> and control traveling to decelerate or stop as needed.

The offset amount determination unit <NUM> is adapted to determine an offset amount with respect to each node of the travel path <NUM> based on the offset information distributed by the own vehicle or the other vehicle and received via the wireless communication device <NUM> and the map information <NUM> representing the travel path <NUM> of the unmanned vehicle <NUM>, and add the determined offset amount to the coordinates of the node, so as to generate a sequence of coordinate points serving as a target track when the unmanned vehicle <NUM> travels, and then send a target track and a target speed to the autonomous travel control unit <NUM>.

The autonomous travel control unit <NUM> is adapted to generate a steering instruction value so that the own-vehicle position approaches the target track, based on the target track sent by the offset amount determination unit <NUM>, the own-vehicle position acquired from the position sensor <NUM>, and the steering angle acquired from the steering angle sensor <NUM>. In addition, the autonomous travel control unit <NUM> is adapted to generate an acceleration/deceleration instruction value so that the own-vehicle speed approaches the target speed, based on the target speed on the target track and the own-vehicle speed acquired from the speed sensor <NUM>. The autonomous travel control unit <NUM> sends the steering instruction value and the acceleration/deceleration instruction value (collectively referred to as a travel instruction) generated in the above processes to the steering motor, the brake, and the travel motor of the travel drive device <NUM>, thereby controlling tracking to the target track.

The offset information distribution unit <NUM> is adapted to determine offset information used when the offset amount determination unit <NUM> of the unmanned vehicle <NUM> determines an offset amount of each node in response to a change in the state of the body (e.g., a change in the body weight), as a trigger, such as when each unmanned vehicle <NUM> performs dumping or the like, and distribute the determined offset information to all of the unmanned vehicles <NUM> via the wireless communication device <NUM>. In the following description of the present embodiment, the offset information will be described as an angle for determining a direction of an offset amount (vector amount), but is not limited thereto. The offset information may be a parameter for determining the angle, or the offset amount itself. Alternatively, the offset information may be a message acting as a trigger for updating the offset amount in each unmanned vehicle <NUM>.

With reference to <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, the following describes the operation of the offset amount determination unit <NUM> to determine an offset amount and generate a target track and the operation of the autonomous travel control unit <NUM> to control the unmanned vehicle <NUM> to travel while tracking the target track.

<FIG> illustrate a method for generating a target track obtained by offsetting a travel path by the offset amount determination unit <NUM>. <FIG> illustrates a single node and <FIG> illustrates a situation of offsetting each of the whole travel paths. In the present embodiment, the offset information distributed by the offset information distribution unit <NUM> of the own vehicle or the other vehicle is assumed to be an angle θ illustrated in <FIG>. Herein, θ is a counterclockwise rotating angle with the X axis as an origin. An open circle <NUM> indicates the coordinates (Xi, Yi) of a given node (node ID: i) on the travel path in the map information <NUM> and a filled circle <NUM> indicates the coordinates (Xi+ΔXi, Yi+ΔYi) of a target track obtained by adding an offset amount (ΔXi, ΔYi) to the coordinates (Xi, Yi). Using the angle θ that is the offset information and an offset factor αi described (held) in the map information <NUM>, the offset amount (ΔXi, ΔYi) regarding the node i is calculated by the following equations:
[Equation <NUM>] <MAT> [Equation <NUM>] <MAT>.

Through the above calculation, as illustrated in <FIG>, each node of the travel path <NUM> of each unmanned vehicle <NUM> is offset in the direction of the common angle θ by a magnitude of the offset factor αi for each node, and then a target track <NUM> of the unmanned vehicle <NUM> can be obtained.

<FIG> and <FIG> each illustrate an example of generating a target track on a curve by the offset amount determination unit <NUM>. <FIG> illustrates an example when the target track is offset in the X-axis direction (θ=<NUM> deg) and <FIG> illustrates an example when the target track is offset in the Y-axis direction (θ=<NUM> deg). Depending on the relation between the advancing direction on the original travel path <NUM> and the angle θ, the target track <NUM> may overlap with the original travel path <NUM>. For example, in a situation illustrated in <FIG>, since the advancing direction on the travel path <NUM> in a section <NUM> is parallel to the X axis and also the direction of the offset amount of each node is along the X-axis direction, the target track <NUM> that is offset with respect to the travel path <NUM> overlaps with the travel path <NUM>. Meanwhile, in a section <NUM>, the target track <NUM> is generated in a position displaced in the width direction with respect to the travel path <NUM>. In another situation illustrated in <FIG>, in the section <NUM>, the target track <NUM> is generated in a position displaced in the width direction with respect to the travel path <NUM>, and in the section <NUM>, the target track <NUM> is generated in a position substantially overlapping with the travel path <NUM>. As described above, even if the target track <NUM> temporarily appears not to be offset with respect to the original travel path <NUM>, a change in the angle θ may allow the target track <NUM> to be generated in a position certainly displaced, at a different time, in the width direction with respect to the travel path <NUM>.

<FIG> is a flowchart of a process procedure of the offset amount determination unit <NUM>. The offset amount determination unit <NUM> first acquires node information (coordinates: (Xi, Yi), i=<NUM>,. ,N) on the travel path <NUM> from the map information <NUM> in the storage device <NUM> (S901). Next, the offset amount determination unit <NUM> determines an offset amount (ΔXi, ΔYi)of each node using the acquired node information on the travel path <NUM> and the latest (common) offset information distributed by the offset information distribution unit <NUM> of the own vehicle or the other vehicle (S902). Then, the offset amount determination unit <NUM> transmits, as the target track <NUM>, a sequence of coordinate points (Xi+ΔXi, Yi+ΔYi) obtained by adding the offset amount to the coordinates of the original nodes to the autonomous travel control unit <NUM> (S903).

<FIG> is a flowchart of a process procedure of the autonomous travel control unit <NUM>. The autonomous travel control unit <NUM> first acquires a target track and a target speed from the offset amount determination unit <NUM> (S1001). Next, the autonomous travel control unit <NUM> acquires an own-vehicle position, an own-vehicle speed, and a steering angle respectively from the position sensor <NUM>, the speed sensor <NUM>, and the steering angle sensor <NUM> (S1002). Then, the autonomous travel control unit <NUM> compares the target track with the own-vehicle position to generate a steering angle instruction value so that the own-vehicle position approaches the target track, and also compares the target speed with the own-vehicle speed to generate an acceleration/deceleration instruction value so that the own-vehicle speed approaches the target speed (S1003). Finally, the autonomous travel control unit <NUM> transmits to the travel drive device <NUM> the generated steering angle instruction value and acceleration/deceleration instruction value (i.e., travel instruction) (S1004).

As described above, with respect to each node of the travel path <NUM>, the offset amount determination unit <NUM> determines an offset amount for every node and generates the target track <NUM>, and then the offset information distribution unit <NUM> determines offset information so as to change the angle θ (for example, change of every several tens of degrees from the current direction of the offset amount) every time and distributes the determined offset information (described later). Accordingly, the target track <NUM>, along which the unmanned vehicle <NUM> actually travels while tracking, can be displaced around the travel path <NUM>, and since the unmanned vehicle <NUM> travels while tracking the target track <NUM>, it is possible to suppress generation of ruts. In addition, since common offset information is used to determine the offset amount of the travel path <NUM> in all of the unmanned vehicles <NUM>, the unmanned vehicles <NUM> passing each other on the transportation path travel with displacement in the same direction. This can avoid a collision risk due to the proximity of the unmanned vehicles <NUM>.

Next, with reference to <FIG> and <FIG>, the following describes advantages of the feature in which different offset amounts can be set to each node.

<FIG> illustrates an example of generating a target track based on an offset amount according to a road width. The offset factor αi of each node set in advance in the map information <NUM> is determined as a distance by which the travel path <NUM> can be offset considering the distance to the road shoulder (corresponding to a road width) on each point. For example, in a section <NUM> having a large road width, the offset factor αi of each node is set relatively large, and in a section <NUM> having a small road width, the offset factor αi of each node is set relatively small. Then, in a section <NUM> between these sections as a buffer section, for example, the offset factor αi of each node may be set such that the offset factor αi is continuously changed to linearly interpolate the values in the adjacent sections. For example, in the travel path <NUM> from the section <NUM> toward the section <NUM>, αw and αn are respectively set as the offset factor of the section <NUM> and the offset factor of the section <NUM> based on the road width of each section. Then, when the number of nodes in the buffer section <NUM> is N, provided that the offset factor of kth node in the buffer section <NUM> is αk (k=<NUM>,. ,N), αk can be calculated by the following equation:
[Equation <NUM>] <MAT>.

Since the above configuration allows adjusting the displacement level of the target track <NUM> of the unmanned vehicle <NUM> within an acceptable range according to the road width of each section, it is possible to suppress generation of ruts more certainly in the section having a large road width, and prevent the unmanned vehicle <NUM> from interfering with the road shoulder in the section having a small road width. Also in the section therebetween, it is possible to continuously change the magnitude of the offset amount so as to smoothly connect the target track <NUM>.

<FIG> illustrates an example of generating a target track based on an offset amount determined considering a fixed work point, such as a loading point of the excavator <NUM> or the like. A node <NUM>-<NUM> is defined by coordinates of the fixed work point on which the unmanned vehicle <NUM> should stop with its own-vehicle position matched therewith so that the excavator <NUM> performs loading work for the unmanned vehicle <NUM>. In addition, among a section <NUM> to a section <NUM> of the travel path <NUM>, the section <NUM> and the section <NUM> are located on the transportation path and the section <NUM> and the section <NUM> are located within the wide loading place. The section <NUM> includes a node for a switchback so that the unmanned vehicle <NUM> approaches the excavator <NUM> while moving backward.

In the travel path <NUM> including such a fixed work point, when the offset factor αi=<NUM> is set, it is possible to match the target track <NUM> and the original travel path <NUM> at the node of the fixed work point and, control the unmanned vehicle <NUM> to stop at a desired position also in the present control. For example, when an offset factor of each node in the sections <NUM>, <NUM> is determined by linear interpolation, first, the following are set: in the section <NUM>, the number of nodes is N (the final node is the fixed work point); in the section <NUM>, the number of nodes is (M-N); in the sections <NUM>, <NUM>, the offset factor of the kth node is αk (k=<NUM>,. ,M); in the section <NUM>, the offset factor of the final node <NUM>-<NUM> is formally α<NUM>; each of α<NUM> and, in the section <NUM>, the offset factor αM (corresponding to the offset factor of the section <NUM>) of the final node <NUM>-<NUM> is a constant. Then, the offset factor αk (k=<NUM>,. ,M-<NUM>) therebetween can be calculated by the following equations:
[Equation <NUM>] <MAT> [Equation <NUM>] <MAT>.

By determining the offset factors in the travel path <NUM> including the fixed work point as described above, the target track <NUM> can be matched with the original travel path <NUM> at a desired position (i.e., the fixed work point) where the unmanned vehicle <NUM> should stop. In addition, at the point adjacent to the desired position (i.e., the fixed work point), it is possible to displace the track and suppress generation of ruts while smoothly connecting the target track <NUM>.

Next, with reference to <FIG> and <FIG>, the operation of the offset information distribution unit <NUM> to update offset information will be described.

When a change in the state of the body set in advance is detected, the offset information distribution unit <NUM> determines offset information based on the offset information currently held therein, and distributes the latest offset information to all of the unmanned vehicles <NUM> via the wireless communication device <NUM>. All of the unmanned vehicles <NUM> (specifically, the unmanned vehicles <NUM> other than the unmanned vehicle <NUM> that has distributed the latest offset information) receive the latest (common) offset information transmitted by a certain unmanned vehicle <NUM> (or the offset information distribution unit <NUM> thereof) via the wireless communication device <NUM> and update offset information used by the offset amount determination unit <NUM> of the own vehicle, then determine the offset amount of each node (travel path <NUM>), generate the target track <NUM>, and control tracking to the target track <NUM> as described above. It should be noted that the unmanned vehicle <NUM> that distributes the latest offset information can update, using the latest offset information, offset information used by the offset amount determination unit <NUM> of the own vehicle. In the present embodiment, an example in which the unmanned vehicle <NUM> updates offset information when the load sensor <NUM> detects that dumping has completed (dumping work has completed) will be described.

<FIG> illustrate a travel trajectory of the unmanned vehicle <NUM> on a dumping place and a transportation path around it. <FIG> illustrates a situation at a time when an unmanned vehicle <NUM>-<NUM> performs dumping. <FIG> illustrates a situation at a time when a following unmanned vehicle <NUM>-<NUM> is at a switch-back point. <FIG> illustrates a situation at a time when the following unmanned vehicle <NUM>-<NUM> performs dumping.

In <FIG>, when the unmanned vehicle <NUM>-<NUM> has completed dumping, at the same time, the offset information distribution unit <NUM> obtains, as new offset information, θ+Δθ by adding a predetermined change Δθ (for example, several tens of degrees) to the angle θ, which is the offset information currently held therein, and distributes the new offset information to all of the unmanned vehicles <NUM> via the wireless communication device <NUM>. That is, when transmitting offset information, the offset information distribution unit <NUM> of the unmanned vehicle <NUM>-<NUM> changes the angle θ (direction of the offset amount), which is the offset information currently held therein, by a predetermined angle Δθ from the current direction, and updates the offset information. Accordingly, the target track <NUM>, along which the unmanned vehicle <NUM> actually travels while tracking, can be displaced around the travel path <NUM>. Next, in <FIG>, the unmanned vehicle <NUM>-<NUM>, which is the vehicle following the unmanned vehicle <NUM>-<NUM>, is at the switchback point. At this time, sections in which the unmanned vehicles <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> have traveled by the current time after the time illustrated in <FIG> are indicated by dashed lines <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, respectively. Since these sections cannot cover the whole travel path, updating again the offset information at this timing may generate, in the target track based on the current offset information, a section in which the unmanned vehicle <NUM> has actually traveled and a section in which the unmanned vehicle <NUM> has not traveled. This may cause nonuniform displacement of the actual travel track in the advancing direction on the travel path. Meanwhile, in <FIG> illustrating the situation after some time has passed and the unmanned vehicle <NUM>-<NUM> has completed dumping, the sections <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> illustrated in <FIG> are further extended and now cover all sections in the travel path. If the offset information distribution unit <NUM> can update offset information after the time illustrated in <FIG> and at the timing illustrated in <FIG>, the sections in which the unmanned vehicle <NUM> has actually traveled along the target track based on the current offset information can cover the whole transportation path. This allows the actual travel track to be uniformly displaced also in the advancing direction on the travel path. Accordingly, when the unmanned vehicle <NUM>-<NUM> has completed dumping, at the same time, the offset information distribution unit <NUM> obtains, as new offset information, θ+Δθ by adding a predetermined change Δθ (for example, several tens of degrees) to the angle θ, which is the offset information currently held therein, and distributes the new offset information to all of the unmanned vehicles <NUM> via the wireless communication device <NUM>. That is, when transmitting offset information, the offset information distribution unit <NUM> of the unmanned vehicle <NUM>-<NUM> changes the angle θ (direction of the offset amount), which is the offset information currently held therein, by a predetermined angle Δθ from the current direction, and updates the offset information.

As described above, updating offset information at a timing when the unmanned vehicle <NUM> has completed dumping can synchronize travel time intervals of the unmanned vehicles <NUM> and time intervals for updating offset information. This allows the whole travel path <NUM> to be covered by the sections in which the unmanned vehicle <NUM> actually travels along the target track <NUM> using offset information. Therefore, it is possible to uniformly displace the travel track also in the advancing direction on the path and suppress generation of ruts.

<FIG> is a flowchart of a process procedure of the offset information distribution unit <NUM>. First, if the offset information distribution unit <NUM> determines that the loaded state has been changed to the empty load state based on a change in the payload weight measured by the load sensor <NUM>, the offset information distribution unit <NUM> detects that dumping has completed (S1201). Next, the offset information distribution unit <NUM> acquires from the offset amount determination unit <NUM> offset information θ, which is currently used (S1202), and determines new offset information (updated value) θ+ based on the currently used offset information θ (S1203). For example, the offset information distribution unit <NUM> adds a predetermined change Δθ to the angle θ, which is currently used, and determines, as new offset information (updated value) θ+, angle θ+Δθ (i.e., a direction obtained by changing the direction of the offset amount from the current direction by a predetermined angle). Then, the offset information distribution unit <NUM> distributes the new offset information θ+ to the offset amount determination unit <NUM> of the own vehicle and updates the offset information used by the offset amount determination unit <NUM> of the own vehicle (S1204), and distributes the same new offset information θ+ also to the offset amount determination unit <NUM> of the other vehicle via the wireless communication device <NUM> (S1205). In the present embodiment, distributing offset information from the own vehicle to the other vehicle and receiving offset information at the other vehicle can be performed by intervehicle communication, not via a control station.

<FIG> is a flowchart of a process procedure of updating the offset information held by the offset amount determination unit <NUM> when offset information is received from the other vehicle. First, the offset amount determination unit <NUM> initializes the offset information (θ=θ<NUM>) of the own vehicle at a predetermined timing (for example, on startup or the like) (S1301). Next, the offset amount determination unit <NUM> determines whether new offset information (updated value) θ+ has been received from the offset information distribution unit <NUM> of the own vehicle or the other vehicle (S1302), and if received (S1302/Yes), updates (θ=θ+) the offset information of the own vehicle using the received updated value θ+ (S1303).

Through the update processes of <FIG> and <FIG>, the unmanned vehicles <NUM> can standardize (share) the offset information generated by each vehicle.

It should be noted that in the present embodiment, although the update and distribution of offset information is performed at a dumping completion timing, as long as the timing of the update and distribution of offset information is a timing in accordance with the operation period of the unmanned vehicle <NUM>, such as a timing when loading starts, loading completes, dumping starts, the unmanned vehicle <NUM> passes a specific point on the travel path, and the like, the offset information can be updated in synchronous with the travel time intervals of the unmanned vehicles <NUM>, and the same advantageous effect can be obtained. In the same manner as the dumping completion timing, a timing when loading starts, loading completes, dumping starts, and the like can be detected based on the load condition of the body acquired by the load sensor <NUM>, specifically, a change in the body weight acquired by the load sensor <NUM>. However, in the present example, it is desirable that offset information be updated and distributed and the offset information be received at the other vehicle via the wireless communication device <NUM> at a predetermined timing based on (i.e., associated with) the load condition of the body acquired by the load sensor <NUM>, specifically when the load sensor <NUM> detects a change in the body weight related to when dumping work completes, dumping work starts, loading work starts, or loading work completes, rather than when the unmanned vehicle <NUM> passes a specific point on the travel path.

In addition, to avoid a situation in which wireless communication is disconnected at a timing when offset information is distributed and the offset information cannot be received, each unmanned vehicle <NUM> may manage a timing of updating offset information based on the time held in each unmanned vehicle <NUM>. In such a case, to synchronize timings of updating offset information in the unmanned vehicles <NUM>, as in the above-described manner, an offset information updating message is transmitted to other vehicles when dumping has completed, and the update periods are synchronized in the unmanned vehicles <NUM>.

As described above, according to the present embodiment, with reference to the map information <NUM> representing the travel path <NUM> of the unmanned vehicle <NUM>, all of the unmanned vehicles <NUM> in the autonomous travel system <NUM> can generate the target track <NUM> obtained by offsetting the travel path <NUM> using common offset information. In addition, since it is possible to displace the target track <NUM> by changing (updating) offset information at a predetermined timing, it is possible to displace the travel position of the unmanned vehicle <NUM> with respect to the travel path <NUM> in the width direction of the path, whereby generation of ruts can be effectively suppressed. In addition, since it is possible to offset the target track <NUM> in the same direction by generating the target track <NUM> using the common offset information among all of the unmanned vehicles <NUM>, the unmanned vehicles <NUM> traveling in opposite lanes can pass each other without approaching, while maintaining a safe distance therebetween.

In addition, according to the present embodiment, since it is possible to set a magnitude of an offset amount according to the road width on each point on the travel path <NUM> by determining an offset factor for each point, for example, it is possible to suppress generation of ruts by increasing an offset amount in a place having a large road width and prevent the unmanned vehicle <NUM> from interfering with the road shoulder by decreasing an offset amount in a place having a small road width. Furthermore, since the target track <NUM> matching with the original travel path <NUM> can be generated by setting an offset amount of <NUM> in the fixed work point, such as a loading position, for example, it is also possible to set the target track <NUM> such that the unmanned vehicle <NUM> passes a required work point.

In addition, according to the present embodiment, since each unmanned vehicle <NUM> updates offset information at a predetermined timing (for example, a timing when dumping has completed), it is possible to synchronize travel time intervals of the unmanned vehicles <NUM> and time intervals for updating offset information. This allows the target track <NUM> based on each piece of offset information to cover the whole travel path. Accordingly, the travel track can be uniformly displaced also in the advancing direction on the travel path, and generation of ruts can further be suppressed.

A second embodiment applies the method of the first embodiment, and the following describes a method in which the offset amount determination unit <NUM> determines an offset amount according to the load condition of the unmanned vehicle <NUM>. Hereinafter, description of configurations and operations that overlap with those of the first embodiment will be omitted, and the following describes only different parts.

<FIG> illustrates an example of data representing the map information <NUM> according to the second embodiment. In the present embodiment, each node of the map information <NUM> holds both of an empty-load offset factor and a load offset factor.

<FIG> is a flowchart of a process procedure of the offset amount determination unit <NUM> according to the present embodiment. The offset amount determination unit <NUM> first acquires node information (coordinates: (Xi, Yi), i=<NUM>,. ,N) on the travel path <NUM> from the map information <NUM> in the storage device <NUM> (S1501). Next, the offset amount determination unit <NUM> determines, based on information obtained by the load sensor <NUM>, the load condition of the own vehicle, that is, whether the own vehicle is in the loaded state or the empty load state (S1502). Then, in the acquired node information on the travel path <NUM>, the offset amount determination unit <NUM> acquires (selects) an offset factor according to the load condition of the own vehicle, that is, either a load offset factor when the own vehicle is in the loaded state or an empty-load offset factor when the own vehicle is in the empty load state, and determines an offset amount of each node (ΔXi, ΔYi)using the acquired offset factor and the latest (common) offset information distributed by the offset information distribution unit <NUM> of the own vehicle or the other vehicle (S1503). Then, finally, the offset amount determination unit <NUM> transmits, as the target track <NUM>, a sequence of coordinate points (Xi+ΔXi, Yi+ΔYi) obtained by adding the offset amount to the coordinates of the original nodes to the autonomous travel control unit <NUM> (S1504).

<FIG> illustrates a target track using an offset amount according to the load condition of the unmanned vehicle <NUM>. In <FIG>, the unmanned vehicle <NUM>-<NUM> is a vehicle (moving from the dumping place to the loading place) in the empty load state, and the unmanned vehicle <NUM>-<NUM> is a vehicle (moving from the loading place to the dumping place) in the loaded state. The load offset factor (i.e., the offset factor when the body weight is relatively large) is set larger than the empty-load offset factor (i.e., the offset factor when the body weight is relatively small), so that the unmanned vehicle <NUM> when loaded can more largely displace the target track <NUM> with respect to the travel path <NUM>. In this case, it is required to set values of offset factors considering a road width and a distance to an opposite lane such that there is a sufficient distance, if offset, to the on-coming vehicle.

According to the present embodiment, the offset amount determination unit <NUM> determines an offset amount according to the load condition (e.g., a change in the body weight) of the unmanned vehicle <NUM>. Specifically, the offset amount determination unit <NUM> holds in advance, as the map information <NUM>, an offset factor when the unmanned vehicle <NUM> is unloaded and an offset factor when the unmanned vehicle <NUM> is loaded at each node (each point), and selects an offset factor to be used for determination of an offset amount based on the load condition (e.g., a change in the body weight) of the unmanned vehicle <NUM>. This can displace the target track <NUM> more largely for the vehicle in the loaded state, which tends to put a large load on the road surface and generate a rut, than in the empty load state. Thus, it is possible to reduce the likelihood that, in the transportation path, the travel path on which the loaded vehicles frequently travel, that is, the travel path from the loading place toward the dumping place, and the like, will have more ruts than the travel path on which the unloaded vehicles on the opposite lane frequently travel, that is, the travel path from the dumping place toward the loading place.

In addition, the offset amount determination unit <NUM> may not independently hold an offset factor according to the load condition as in the present embodiment, and may determine an offset amount of each node considering (in view of) a total weight of the body using a single offset factor as illustrated in <FIG>. In such a case, using the offset factor αi and a total weight M of the body acquired by the load sensor <NUM>, an offset amount (ΔXi, ΔYi) regarding the node i can be calculated by the following equations:
[Equation <NUM>] <MAT> [Equation <NUM>] <MAT>.

With such a configuration, also when each node of the map information <NUM> has a single offset factor, it is possible to give an offset amount considering the load condition of the body, and for the vehicle in the loaded state, which puts a large load on the road surface when traveling, it is possible to displace the target track <NUM> more largely than for the vehicle in the empty load state, and suppress generation of ruts.

As in the first embodiment, since it is possible to offset the target track <NUM> in the same direction by generating the target track <NUM> using the common offset information among all of the unmanned vehicles <NUM>, the unmanned vehicles <NUM> traveling in opposite lanes can pass each other without approaching, while maintaining a safe distance therebetween.

A third embodiment applies the method of the first embodiment, and the following describes an example in which offset information is distributed to the unmanned vehicle <NUM> via a control station (not by intervehicle communication) and all of the unmanned vehicles <NUM> receive offset information via the control station. Hereinafter, description of configurations and operations that overlap with those of the first embodiment will be omitted, and the following describes only different parts.

<FIG> is a diagram illustrating a schematic configuration of the autonomous travel system <NUM> according to the third embodiment. In addition to the configuration of the first embodiment, the autonomous travel system <NUM> of the present embodiment includes a control station <NUM> that is communicably connected to the unmanned vehicles <NUM> via the wireless network <NUM>.

<FIG> is a block diagram of the autonomous travel system <NUM> according to the third embodiment. The autonomous travel system <NUM> includes the control station <NUM> and the plurality of unmanned vehicles <NUM>.

The unmanned vehicle <NUM> of the present embodiment is different from that of the first embodiment (<FIG>) in that the in-vehicle control device <NUM> does not include an offset information distribution unit <NUM> that determines and distributes offset information, but further includes a vehicle state notification unit <NUM> adapted to transmit body information based on data acquired from various sensors to the control station <NUM> via the wireless communication device <NUM>. Except for such a configuration, the unmanned vehicle <NUM> of the present embodiment is equal to that of the first embodiment.

The vehicle state notification unit <NUM> transmits to the control station <NUM> at least the load condition of the unmanned vehicle <NUM> based on the data acquired from the load sensor <NUM>.

The control station <NUM> includes a control device <NUM>, a control storage device <NUM>, and a control wireless communication device <NUM>.

The control device <NUM> includes a CPU (central processing unit), RAM (random access memory), and ROM (read only memory), which individually perform calculation of a program, perform reading and writing information from and to a work area, and temporarily store the program, so as to control the operation of the control station <NUM>.

The control storage device <NUM> is an information readable/writable non-volatile storage medium, and stores an operating system (OS), various control programs, application programs, databases, and the like.

The control wireless communication device <NUM> is radio equipment for connection to the wireless network <NUM>, capable of communicating information with the outside.

The control device <NUM> includes a dispatch management unit <NUM> and an offset information distribution unit <NUM>.

The control storage device <NUM> includes dispatch information <NUM> and map information <NUM>. Herein, the map information <NUM> is common to that stored in the storage device <NUM> of the unmanned vehicle <NUM>.

The dispatch management unit <NUM> of the control device <NUM> determines a destination of the unmanned vehicle <NUM> and a target path to reach the destination. For example, when the unmanned vehicle <NUM> is at the loading place, the dispatch management unit <NUM> sets a target path to reach the dumping place. When the unmanned vehicle <NUM> is at the dumping place, the dispatch management unit <NUM> sets a target path to reach the loading place.

<FIG> illustrates an example of a table of the dispatch information <NUM>. The dispatch information <NUM> stores a vehicle ID that uniquely identifies each unmanned vehicle <NUM> and a target path determined by the dispatch management unit <NUM>. The dispatch management unit <NUM> sets a target path of each unmanned vehicle <NUM> and, at the same time, transmits the target path to the appropriate unmanned vehicle <NUM> via the wireless network <NUM>.

The offset information distribution unit <NUM> of the control device <NUM> determines offset information based on the information received from the vehicle state notification unit <NUM> of each unmanned vehicle <NUM>, and distributes the offset information to the offset amount determination unit <NUM> of each unmanned vehicle <NUM> via the control wireless communication device <NUM> and the wireless network <NUM>.

<FIG> is a flowchart of a process flow of the offset information distribution unit <NUM> according to the present embodiment. The offset information distribution unit <NUM> receives the load condition of each unmanned vehicle <NUM> from the vehicle state notification unit <NUM> of each unmanned vehicle <NUM> (S2001). Based on the received load condition of each unmanned vehicle <NUM>, the offset information distribution unit <NUM> determines whether there is a new unmanned vehicle <NUM> that has completed dumping (S2002). If there is no new unmanned vehicle <NUM> that has completed dumping (S2002/No), the offset information distribution unit <NUM> waits for next reception without any action. If there is a new unmanned vehicle <NUM> that has completed dumping (S2002/Yes), the offset information distribution unit <NUM> determines new offset information based on the set offset information. For example, the offset information distribution unit <NUM> determines, as new offset information, angle θ+Δθ (i.e., a direction obtained by changing the direction of the offset amount from the current direction by a predetermined angle) by adding a predetermined change Δθ (for example, several tens of degrees) to the angle θ that is currently used (S2003). Then, the offset information distribution unit <NUM> distributes the new offset information to all of the unmanned vehicles <NUM> (or the offset amount determination units <NUM> thereof) via the control wireless communication device <NUM> (S2004).

In response to the load condition of the unmanned vehicle <NUM> transmitted from the vehicle state notification unit <NUM> of a certain unmanned vehicle <NUM> (dumping completion timing, herein), as a trigger, all of the unmanned vehicles <NUM> receive, via the wireless communication devices <NUM>, the latest (common) offset information transmitted from the offset information distribution unit <NUM> of the control station <NUM> and update the offset information used by the offset amount determination unit <NUM> of the own vehicle, then determine the offset amount of each node (travel path <NUM>), generate the target track <NUM>, and control tracking to the target track <NUM> as described above.

It should be noted that also in the present embodiment, in the same manner as the foregoing first embodiment, as long as the timing of the update and distribution of offset information is a timing in accordance with the operation period of the unmanned vehicle <NUM>, such as a timing when loading starts, loading completes, dumping starts, the unmanned vehicle <NUM> passes a specific point on the travel path, and the like, other than the dumping completion timing, the offset information can be updated in synchronous with the travel time intervals of the unmanned vehicles <NUM>, and the same advantageous effect can be obtained. However, also in the present example, it is desirable that offset information be updated and distributed at the control station <NUM> (or the offset information distribution unit <NUM> thereof) and the offset information be received at all of the unmanned vehicles <NUM> via the wireless communication devices <NUM> at a predetermined timing based on (i.e., associated with) the load condition of the body acquired by the load sensor <NUM>, specifically when the load sensor <NUM> detects a change in the body weight related to when dumping work completes, dumping work starts, loading work starts, or loading work completes, rather than when the unmanned vehicle <NUM> passes a specific point on the travel path.

According to the present embodiment, since the control station <NUM> has control over determination of offset information and distributes the offset information to all of the unmanned vehicles <NUM>, and each unmanned vehicle <NUM> determines an offset amount based on the offset information distributed from the control station <NUM> and received via the wireless communication device <NUM> and displaces the target track <NUM>, it is possible to effectively suppress generation of ruts. In addition, since all of the unmanned vehicles <NUM> generate the target track <NUM> using the common offset information distributed from the control station <NUM> and received via the wireless communication devices <NUM> so as to offset the target track <NUM> in the same direction as in the first embodiment, the unmanned vehicles <NUM> traveling in opposite lanes can pass each other without approaching, while maintaining a safe distance therebetween. Furthermore, since the control station <NUM> has control over distribution of offset information, it is also possible to selectively distribute offset information to only the unmanned vehicles <NUM> having the same target path based on the dispatch information <NUM>.

Some or all of the aforementioned structures, functions, processing units, processing means, and the like may be implemented as hardware by designing them into an integrated circuit, for example. Alternatively, each of the aforementioned structures, functions, and the like may be implemented as software such that a processor analyzes and executes a program that implements each function. Information such as the program that implements each function, tables, and files can be stored in a storage device such as memory, a hard disk, or a SSD (Solid State Drive); or a storage medium such as an IC card, an SD card, or a DVD.

Claim 1:
An autonomous travel system (<NUM>) comprising a plurality of vehicles (<NUM>), each including: a travel drive device (<NUM>) adapted to drive a body; a position sensor (<NUM>) for acquiring an own-vehicle position; a storage device (<NUM>) storing map information; an in-vehicle control device (<NUM>) adapted to, based on the own-vehicle position and the map information, output to the travel drive device (<NUM>) a travel instruction to control traveling of the body so as to track a travel path (<NUM>) based on the map information; and a wireless communication device (<NUM>) that can communicate information with an outside,
characterized in that
each of the plurality of vehicles traveling at different locations in the autonomous travel system receives common offset information via the wireless communication device of each vehicle at a common timing, and
wherein based on the common offset information received via the wireless communication device (<NUM>) of each vehicle, the in-vehicle control device (<NUM>) of each of the plurality of vehicles determines an offset amount of the travel path (<NUM>) of the vehicle based on the map information of the vehicle, generates a target track, and outputs a travel instruction to control traveling of the body of the vehicle so as to track the target track to which the offset amount has been added based on the target track and the own-vehicle position of the vehicle.