CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the United States national phase of International Application No. PCT/JP2017/042871 filed Nov. 29, 2017, and claims priority to Japanese Patent Application No. 2016-235232 filed Dec. 2, 2016, Japanese Patent Application Nos. 2016-245799 and 2016-245800 filed Dec. 19, 2016, Japanese Patent Application No. 2017-221343 filed Nov. 16, 2017, and Japanese Patent Application No. 2017-221901 filed Nov. 17, 2017, the disclosures of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a travel route management system that determines a travel route for a work vehicle that travels autonomously while working at a work site.

The present invention furthermore relates to a travel route determination device that determines a travel route for a work vehicle that travels while working at a work site.

BACKGROUND ART

[1] A field working machine disclosed in Patent Document 1 includes a route calculating part and a drive assist unit for working in a field while traveling autonomously. The route calculating part finds the outer shape of the field from topographical data. Then, on the basis of the outer shape and a work width of the field working machine, the route calculating part calculates a travel route that starts from a travel start point to a travel endpoint. The drive assist unit compares a vehicle position found from positioning data (latitude/longitude data) obtained from a GPS module with the travel route calculated by the route calculating part. The drive assist unit then controls a steering mechanism so that the vehicle body travels along the travel route.

Patent Document 1 discloses a system that controls the autonomous travel of a single work vehicle. Patent Document 2 discloses a system that causes two work vehicles to work while traveling in tandem. A travel route setting device used in this system calculates a travel route by selecting deployment positions of a first work vehicle and a second work vehicle. Once the travel route is calculated, the work vehicles measure their own positions and work while traveling along the travel route.

[2] The field working machine disclosed in Patent Document 1 includes a route calculating part and a drive assist unit for working in a field using autonomous travel. The route calculating part finds the outer shape of the field from topographical data. Then, on the basis of the outer shape and a work width of the field working machine, the route calculating part calculates a travel route that starts from a travel start point to a travel endpoint that have been set. The drive assist unit compares a vehicle position found on the basis of positioning data (latitude/longitude data) obtained from a GPS module with the travel route calculated by the route calculating part. The drive assist unit then controls a steering mechanism so that the vehicle body travels along the travel route.

According to Patent Document 1, an overall travel route covering the field is calculated before travel, and work travel is carried out along the overall travel route. If, when calculating this overall travel route, the computations are optimized by taking various conditions into account, the computational load will increase. It therefore takes a long time to obtain the computation results, which delays the start of the work travel. On the other hand, lightening the computational load by omitting various conditions makes it possible to obtain the overall travel route in a short time. However, it is highly likely that the work will be inefficient as a result.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: JP 2015-112071A

Patent Document 2: JP 2016-093125A

DISCLOSURE OF THE INVENTION

Problems the Invention is to Solve

[1] One problem pertaining to background art [1] is as follows.

In the autonomous work travel of the work vehicles according to Patent Document 1 and Patent Document 2, the travel route for working in a work site is calculated on the basis of the outer shape of the work site, the specifications of the work vehicles, and so on. One or more work vehicles then travel autonomously along the calculated travel route. The calculated travel route has a form in which the route extends so as to cover the work site with a single stroke. A travel route that covers a work site by repeating straight travel of long distances and U-turn travel that changes the travel direction is typically calculated as the travel route. In such a travel route, various types of routes are used for the U-turn travel routes, including routes constituted only by a turning travel route, routes constituted by a turning travel route and a straight travel route, routes constituted by counter travel routes of moving forward and backward, and the like. Additionally, work vehicles that carry out agricultural work and the like often work while traveling straight and stop working temporarily during U-turn travel. In U-turn travel, turning with too low a turn radius is problematic in that doing so risks damaging the ground surface, whereas turning with too high a turn radius is problematic in that doing so requires a larger space for the U-turn travel and reduces the work efficiency. However, conventional travel routes for autonomous work travel have not taken these problems into account.

In light of such circumstances, what is needed is a travel route management system capable of rationally selecting a U-turn travel route.

[2] Another problem pertaining to background art [1] is as follows.

In the autonomous work travel of the work vehicles according to Patent Document 1 and Patent Document 2, the travel route for working in a work site is calculated on the basis of the outer shape of the work site, the specifications of the work vehicles, and so on. One or more work vehicles then travel autonomously along the calculated travel route. The routes travelled by the work vehicle are defined by travel patterns. A “travel pattern” is the basic form of the travel route. In Patent Document 1 and Patent Document 2, back-and-forth travel, which covers the work site while repeating straight travel of long distances and U-turn travel that changes the travel direction, is used as the travel pattern. Counterclockwise or clockwise spiral travel moving from the outside toward the inside, counterclockwise or clockwise spiral travel moving from the inside toward the outside, and the like are known as travel patterns aside from back-and-forth travel. The travel pattern suited for actual autonomous travel depends on the state of the work site, the type of the work, and so on. There is also demand for a user to be able to determine the travel pattern according to his or her preferences. The state of the work site also changes over time. In spite of this, the travel pattern serving as the basis for generating the travel route is determined in advance in conventional autonomous travel systems. It has thus not been possible to determine a travel pattern in accordance with the state of the work site on that day, the user's intentions, and so on.

In light of such circumstances, what is needed is a system that enables a travel pattern for autonomous travel to be selected in accordance with the state of a work site, user preferences, and the like.

[3] A problem pertaining to background art [2] is as follows.

In light of such circumstances, what is needed is a technique for implementing work travel along the most suitable travel route possible, without delaying the start of the work travel.

Means to Solve the Problems

[1] A solution corresponding to problem [1] is as follows.

A travel route management system according to the present invention, which determines a travel route for a work vehicle that travels autonomously while working in a work site, includes: an area setting unit that sets the work site to an outer peripheral area, and an area to be worked on an inner side of the outer peripheral area; and a route element selecting unit that sequentially selects a next travel route element to be traveled on next, from among multiple mutually-parallel travel route elements, the travel route elements constituting a travel route that covers the area to be worked, wherein the route element selecting unit selects a U-turn travel route for moving from a travel route element serving as a movement origin to a next travel route element serving as a movement destination, the selection being made on the basis of an interval between the movement origin and the movement destination.

According to this configuration, to carry out work travel in the entire area to be worked, the work vehicle does not simply connect adjacent travel route elements with a U-turn travel route. Instead, the U-turn travel route is selected in accordance with an interval from the travel route element serving as the movement origin to the travel route element serving as the movement destination to connect to. As a result, multiple mutually-parallel travel route elements set in the area to be worked are sequentially connected by U-turn travel routes at intervals that are as appropriate as possible, based on the state of the work site, the type of the work, and so on. If only intervals that cannot connect the travel route elements to each other are found, a U-turn travel route connecting the travel route elements by that interval is selected. Multiple mutually-parallel travel route elements set in the area to be worked can be connected by selecting a U-turn travel route in accordance with the interval. As a result, work travel using a reasonable travel route for autonomous travel can be realized.

Incidentally, in work sites such as fields entered by agricultural work vehicles, the outer peripheral area located on the outer side of the area to be worked of the work site is typically used as an area in which the work vehicle can travel freely. It is therefore favorable to set the U-turn travel route in the outer peripheral area. Thus according to one preferred embodiment of the present invention, the U-turn travel route is a travel route set in the outer peripheral area.

According to one preferred embodiment of the present invention, a first U-turn travel route that realizes normal U-turn travel carried out only in a forward direction, and a second U-turn travel route that realizes switchback turn travel carried out in both forward and reverse directions, can be calculated as the U-turn travel route; and the route element selecting unit selects the first U-turn travel route when the interval is large and the second U-turn travel route when the interval is small. According to this configuration, when the interval from the travel route element serving as the movement origin to the travel route element serving as the movement destination is so short that the work site will be damaged beyond the permissible level by normal U-turn travel, or if normal U-turn travel is not possible, switchback turn travel, which includes counter travel using forward and backward movement, can be selected. Additionally, this configuration makes it possible to avoid, to the greatest extent possible, selecting a travel route element having an interval requiring switchback turn travel as the travel route element serving as the movement destination. Through this, switchback turn travel, which requires complex steering control, can be suppressed to the greatest extent possible, while at the same time executing such switchback turn travel depending on the interval, which makes it possible to realize reasonable travel routes.

Furthermore, according to a preferred embodiment of the present invention, the first U-turn travel route includes a rightward U-turn travel route and a leftward U-turn travel route; and the route element selecting unit selects the leftward U-turn travel route preferentially over the rightward U-turn travel route. Agricultural work vehicles such as tractors conventionally travel mainly leftward (counterclockwise). Thus according to the stated configuration, a sense of unnaturalness can be avoided when a person occupies the autonomously-traveling work vehicle for monitoring purposes. This is also advantageous in that a sense of unnaturalness can be avoided even when monitoring the autonomously-traveling work vehicle from the exterior.

[2] A solution corresponding to problem [2] is as follows.

A travel route management system according to the present invention determines a travel route for a work vehicle that travels autonomously while working in a work site, the system including: an area setting unit that sets the work site to an outer peripheral area, and an area to be worked on an inner side of the outer peripheral area; a route managing unit that calculates a travel route element set, the travel route element set being an aggregate of multiple travel route elements constituting a travel route covering the area to be worked, and manages the travel route element set so as to be capable of readout, and furthermore manages a plurality of types of directional change routes so as to be capable of readout, the directional change routes being used to move from one of the travel route elements to another travel route element; and a route element selecting unit that, on the basis of a travel pattern set from among a plurality of types of travel patterns defined by combinations of the travel route elements and the directional change routes, selects the next travel route element to be traveled next from the travel route element set in sequence, and selects the directional change travel route for moving to the next travel route element, wherein the setting of the travel pattern is carried out by a human, through a user instruction. Note that “setting a travel pattern through a user instruction” includes not only a user making a setting directly in a control unit of the work vehicle, but also setting a travel pattern by downloading a work plan created on the basis of a user request to the control unit of the work vehicle.

According to this system, a plurality of travel patterns are prepared. Then, the form of a travel route on which the work vehicle will actually travel is determined on the basis of the travel patterns. Moreover, the travel patterns can be determined in accordance with user instructions. The travel patterns can be determined in accordance with the state of the work site, user preferences, and the like. As a result, the work vehicle autonomously travels on a travel route, based on a travel pattern determined according to the user's preferences, as a target route.

If the work site is a field in which crops are being grown, many crops are planted in rows. As such, back-and-forth travel that uses U-turns to connect multiple parallel long-distance instances of forward travel is preferable in tilling work, harvesting work, and the like in the field. Accordingly, a travel pattern that defines the form of a route for achieving such back-and-forth travel is necessary. Additionally, in land preparation work, mowing work, liquid dispersion work, and the like in a work site, spiral travel, which is spiral-shaped traveling from the interior or from the exterior, is preferable particularly when the work site is shaped as a polygon with five or more sides. Accordingly, a travel pattern that defines a route for achieving such spiral travel is also necessary. Thus according to one preferred embodiment of the present invention, one type of the travel pattern is spiral travel, the spiral travel being spiral work travel from the outside toward the inside of the area to be worked, and another type of the travel pattern is back-and-forth travel in which a U-turn travel route in the outer peripheral area is used as the directional change route for moving from an endpoint of the travel route element to an endpoint of another travel route element. Accordingly, spiral travel or back-and-forth travel can be selected according to the user's intent, on the basis of the state of the work site, the user's preferences, and the like.

In U-turn travel, a travel pattern that carries out two 90° turns on either side of straight travel (a normal U-turn), a travel pattern that carries out a so-called counter turn in which a reverse-travel part is included (a switchback turn), and the like are used. The turn radius of the work vehicle is large, and thus when turning with a normal U-turn, there is a long interval between the straight travel trajectory before the U-turn and the straight travel trajectory after the U-turn. This interval is greater than or equal to twice the work width of the work vehicle, and thus adjacent travel routes cannot be connected by a normal U-turn. However, a switchback turn introduces counter travel including backward travel, and thus the interval between the straight travel trajectory before the U-turn and the straight travel trajectory after the U-turn can be shortened. Adjacent travel routes can therefore be connected by switchback turns. However, switchback turns include backward travel, and therefore tend to require a longer amount of time than the amount of time required by normal U-turns. It is therefore preferable to employ switchback turns when the interval between the straight travel trajectory before the U-turn and the straight travel trajectory after the U-turn is too short and a normal U-turn is not possible. Thus according to a preferred embodiment of the present invention, the U-turn travel route includes a first U-turn travel route that realizes normal U-turn travel carried out only in a forward direction and a second U-turn travel route that realizes switchback turn travel carried out in both forward and reverse directions; and the route element selecting unit selects the first U-turn travel route when an interval between a travel route element serving as a movement origin and a travel route element serving as a movement destination, which are to be moved to and which are parallel to each other, is large, and selects the second U-turn travel route when the interval is small.

In work travel carried out in a single field, it is not necessary to use a travel route defined by the same travel pattern from start to finish. For example, the beginning of the work travel may be carried out through spiral travel, with U-turn travel set partway through the work, and work travel using U-turn travel being carried out in the remaining unworked site. Thus according to one preferred embodiment of the present invention, the travel pattern can be changed partway through the work travel in the area to be worked. Autonomous travel with a high level of freedom is realized as a result.

For the work vehicle to travel autonomously, it is necessary to set the vehicle speed, work specifications, and the like, in addition to setting the travel pattern. Such settings, which require user confirmation, are preferably made by the user him or herself operating a touch panel, an instrument, or the like to input the necessary information. Thus according to one preferred embodiment of the present invention, the travel pattern is set by a human, through a user input.

[3] A solution corresponding to problem [3] is as follows.

A travel route determination device, which determines a travel route for a work vehicle that travels while working in a work site, includes: an area setting unit that sets an area to be worked by the work vehicle in the work site; a route managing unit that calculates a travel route element set, the travel route element set being an aggregate of multiple travel route elements constituting a travel route covering the area to be worked, and stores the travel route element set so as to be capable of readout; a first route element selecting unit that calculates a selection order for the travel route elements of an overall travel route on the basis of a basic priority rule, before the work travel by the work vehicle; a second route element selecting unit that, while the work vehicle carries out work travel based on the selection order calculated by the first route element selecting unit, extracts an untraveled travel route element from the travel route element set as a recalculated travel route element, and recalculates a selection order for the recalculated travel route element on the basis of a cost evaluation rule; and a route setting unit that corrects the selection order calculated by the first route element selecting unit with the selection order calculated by the second route element selecting unit.

According to this configuration, first, a travel route element set, which covers an area to be worked that has been set, is calculated. The travel route elements constituting the travel route element set are selected sequentially, and by carrying out work travel using the selected travel route elements as a target travel route, the work in the area to be worked is completed. The function of calculating the travel route element selection order is realized by the first route element selecting unit and the second route element selecting unit. Before the work travel, the first route element selecting unit calculates the selection order for the travel route elements of the overall travel route on the basis of a basic priority rule. Once that selection order is calculated, the work vehicle immediately starts work travel. The first route element selecting unit only calculates the selection order on the basis of the basic priority rule, and thus the selection order is a calculation result, obtained with a light processing load and in a short amount of time. However, this selection order is not necessarily appropriate in terms of the work performance, travel performance, economic performance, and so on. It is necessary to add various conditions pertaining to the work performance, travel performance, economic performance, and the like in order to obtain an appropriate selection order. Here, a rule for calculating a travel route element selection order in light of such conditions, which provides more appropriate benefits, is called a “cost evaluation rule”. According to this configuration, the second route element selecting unit extracts a travel route element that has not yet been traveled as a recalculated travel route element, and calculates the selection order on the basis of the cost evaluation rule, at the point in time when the first route element selecting unit has finished calculating the selection order, i.e., at the point in time when the work travel is started. The selection order calculated by the second route element selecting unit is more appropriate than the selection order calculated by the first route element selecting unit, and thus the route setting unit corrects the selection order calculated by the first route element selecting unit using the selection order calculated by the second route element selecting unit. While the second route element selecting unit is carrying out computations, the work vehicle is already traveling for work, which makes it possible to avoid a situation in which the computation time of the second route element selecting unit delays the work travel. Work travel which takes into account the cost and is therefore more appropriate to a degree corresponding to the work travel in the corrected selection order is thus carried out.

Note that the term “work travel” used in this application is used not only in reference to travel executed while actually carrying out work, but with a broader meaning encompassing travel carried out to change directions during the work, in a state where work is not being carried out.

Furthermore, in this specification, the term “work environment of the work vehicle” can include the state of the work vehicle, the state of the work site, commands from a person (a monitoring party, a driver, an administrator, or the like), and so on. State information is found by evaluating the work environment. Mechanical factors such as refueling and unloading harvested crops, environmental factors such as changes in weather and the state of the work site, and furthermore, human requests such as unanticipated commands to suspend the work, can be given as examples of the state information. If multiple work vehicles are executing work travel in cooperation with each other, the positional relationships and so on between the work vehicles also correspond to the work environment or the state information. Note that the monitoring party, the administrator, or the like may be inside the work vehicle, near the work vehicle, or far from the work vehicle.

If, while the second route element selecting unit is calculating the selection order of the recalculated travel route elements, one of the recalculated travel route elements has been traveled on, it will become necessary to again travel on that already-traveled travel route element, which is wasteful. To avoid this, according to one preferred embodiment of the present invention, the second route element selecting unit extracts a predetermined number of travel route elements from the end of the selection order calculated by the first route element selecting unit as the recalculated travel route elements. According to this configuration, a predetermined number of travel route elements from the final travel route element in the selection order are subject to the selection order recalculation. Accordingly, if the calculation time and travel time are taken into consideration, and the predetermined number is set to a number with which the recalculated travel route elements have no chance of being traveled on by the work vehicle, the above-described problem is solved.

The work travel time of the work vehicle and the calculation time of the second route element selecting unit are not constant, and it is therefore difficult to accurately determine a predetermined number that ensures that the work vehicle will not travel on the recalculated travel route elements during the recalculation. If the predetermined number is set to a low number to be on the safe side, a fewer number of travel route elements will have the appropriate selection order. To reasonably solve this problem, according to one preferred embodiment of the present invention, the second route element selecting unit repeats the process of extracting the recalculated travel route element and recalculating the selection order while incrementing the predetermined number by additionally extracting a travel route element later in the selection order, and stops the repeating process when the last additionally-extracted travel route element is the travel route element currently being traveled. According to this configuration, the selection order is recalculated using, as the predetermined number, a number with which there is no chance that the recalculated travel route elements will be traveled by the work vehicle, and if there is further leeway in terms of time, the predetermined number is incremented, the number of recalculated travel route elements is increased, and the selection order is recalculated again. If, when incrementing the predetermined number in this manner, a travel route element additionally extracted as a recalculated travel route element as a result of the incrementing is currently being traveled on, the recalculation is stopped. Accordingly, the selection order corrected using the results of the recalculation obtained up until that time remains valid, and work travel is realized along the most appropriate travel route possible. Note that the term “increment” used in this application is not limited to increasing the predetermined number by one at a time, and a number of two or more may be used instead of one as the number of the increase. Additionally, the actual work travel time and the computation time may be compared, and the number of the increase may be changed at the timing of the incrementing, rather than using a constant increase number.

The area to be worked can be covered by travel routes having a variety of forms. A travel route in which parallel travel routes are connected by U-turn travel routes is commonly used in agricultural work. The work width is defined by the interval of parallel travel routes. Additionally, the U-turn width of the U-turn travel route is defined by a minimum turn radius. The U-turn width is typically greater than the work width, and thus a travel route in which adjacent travel routes are connected by U-turn travel routes cannot be employed. It is therefore necessary to select the next travel route having skipped several travel routes from one travel route. The selection order technique according to the present invention can be used favorably when selecting routes in this manner. Thus according to one preferred embodiment of the present invention, the travel route element set is a parallel line set constituted by parallel lines that are parallel to each other and divide the area to be worked into rectangular shapes, and movement from one end of one travel route element to one end of another travel route element is executed through U-turn travel by the work vehicle.

As described above, with a basic priority rule, which is favorable when employing a parallel line set as the travel route element set, a priority level from the travel route element previous in the order to the travel route element next in the order is set in advance. Preferably, this priority level is set so that a properly-distanced travel route element, which is a predetermined distance from the travel route element previous in the order, has the highest priority as the next element in the order. Furthermore, it is preferable that the priority level be set to decrease as the distance from the travel route element previous in the order to the travel route element next in the order increases. Using such a basic priority rule makes it possible to quickly and easily determine the selection order for the travel route elements, and thus the computations end in a short amount of time even when there is a large number of travel route elements.

With respect to the cost evaluation rule used after the selection order calculation using the basic priority rule, preferably, a cost evaluated by the cost evaluation rule is a cost arising when the work vehicle travels on the travel route elements according to the selection order calculated by the second route element selecting unit; and a selection order where the cost is the lowest is calculated by the second route element selecting unit. In the field of route searching, a more appropriate selection order is obtained by using the cost evaluation rule to calculate a selection order providing the lowest total cost necessary when passing through each travel route element.

In work travel, advantages and disadvantages in terms of fuel costs, stemming from the travel distance, and particularly the travel distance of U-turn travel; the effects of deviation from appropriate steering angles on the work vehicle or the work site; advantages and disadvantages in terms of work quality stemming from the direction of travel; and the like are appropriate as items subject to cost evaluation. Thus even if it takes time to calculate the selection order using the cost evaluation rule, that selection order will be more appropriate than the selection order calculated using the basic priority rule.

