JP2018121538A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution capable of switching smoothly between advancing and backing traveling, in a work vehicle autonomously traveling along a route determined beforehand.SOLUTION: A work vehicle includes wheels and a control part. The control part can control a rotation direction of the wheels, and a steering angle which is a cutting angle of the wheels along a travel route. When the steering angle is a non-neutral angle, the control part can change the rotation direction of the wheels from an advancing direction to a backing direction, or from a backing direction to an advancing direction.SELECTED DRAWING: Figure 9

Description

  The present invention mainly relates to a work vehicle that autonomously travels along a predetermined route.

  2. Description of the Related Art Conventionally, work vehicles that can travel autonomously using a satellite positioning system are known. Patent document 1 discloses this kind of work vehicle. The work vehicle of Patent Literature 1 includes a position calculation unit that measures the position of the aircraft using a satellite positioning system, and a control device that automatically travels and works along a set travel route. The remote control device is configured to be able to communicate with this work vehicle wirelessly. With this configuration, in Patent Document 1, the work vehicle can be remotely operated without an operator getting on the work vehicle.

  Patent Document 2 discloses a work vehicle capable of executing a mode in which the work vehicle is manually driven and a mode in which the work vehicle is autonomously driven while the worker is on the vehicle.

Japanese Patent Laying-Open No. 2015-188423 JP 2014-182453 A

  Here, Patent Documents 1 and 2 do not describe how to control the steering angle when switching from forward to reverse (or vice versa).

  The present invention has been made in view of the above circumstances, and a main object thereof is to provide a configuration capable of smoothly switching between forward and backward travel in a work vehicle that autonomously travels along a predetermined route. There is.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to an aspect of the present invention, a work vehicle having the following configuration is provided. That is, this work vehicle includes wheels and a control unit. The said control part controls the steering angle which is the rotation direction of the said wheel, and the turning angle of the said wheel along the said driving | running route. When the steering angle is a non-neutral angle, the control unit can change the rotation direction of the wheel from the forward direction to the reverse direction, or from the reverse direction to the forward direction.

  As a result, even when the rudder angle is a non-neutral angle, it is possible to switch from forward to reverse, or from reverse to forward, so that it is possible to smoothly switch back and forth.

  In the work vehicle, the control unit may rotate the wheel without changing the rudder angle while the rotation of the wheel is stopped when a determination angle that is a rudder angle with respect to a reference angle is equal to or less than a first angle. It is preferable that the direction can be changed from the forward direction to the reverse direction, or from the reverse direction to the forward direction.

  Thereby, if the determination angle is equal to or smaller than the predetermined first angle, the forward / reverse movement can be smoothly switched. In addition, by setting the first angle as a threshold value, it is possible to prevent the rudder angle from being significantly changed after the forward / reverse switching.

  In the work vehicle, the control unit stops the rotation of the wheel when the determination angle exceeds the first angle, and the determination angle is a first angle or a second angle smaller than the first angle. After the steering angle is changed so as to become, it is preferable to change to the backward direction when the wheel is rotating in the forward direction, and to change to the forward direction when the wheel is rotating in the backward direction.

  As a result, if the judgment angle is large, stop and then change the rudder angle to switch between forward and backward movements, so the fluctuations before and after switching between forward and backward movements can be reduced, or the amount of deviation of the route can be reduced. Can do.

  In the work vehicle, the second angle is preferably a non-neutral angle.

  Thereby, since the forward / reverse switching is performed without reaching the neutral angle, the forward / backward switching can be quickly performed.

  In the work vehicle, the control unit may change the steering angle when there is a difference between the steering angle and the target angle after the rotation direction of the wheel is changed from the forward direction to the reverse direction or from the reverse direction to the forward direction. Is preferably changed to the target angle.

  Thereby, even when there is a difference between the rudder angle and the target angle, the rudder angle is changed after the forward / backward movement of the work vehicle is switched, so that the forward / backward movement can be smoothly switched.

1 is a side view showing an overall configuration of a robot tractor according to an embodiment of the present invention. The top view of a robot tractor. The figure which shows the radio | wireless communication terminal with which an autonomous running system is equipped. The block diagram which shows the main structures of the control system of a robot tractor and a radio | wireless communication terminal. The figure which shows the example of a display of the monitoring screen in the display of a radio | wireless communication terminal. The schematic diagram which shows the example of the autonomous running route which a radio | wireless communication terminal produces | generates. The schematic diagram explaining the flow when turning by switching back and forth. The schematic diagram which shows determination angle (theta) when neutral angle is made into a reference angle. The flowchart which shows the process regarding the steering angle change at the time of switching of a forward / reverse advance. The schematic diagram which shows changing the present position at the time of advance and reverse. The schematic diagram explaining another method of turning by switching back and forth. The schematic diagram which shows determination angle (theta) when making a target angle into a reference angle. The flowchart which shows the process regarding the steering angle change at the time of the start of a forward / backward movement.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following, the same members are denoted by the same reference symbols in the drawings, and redundant description may be omitted. In addition, names of members and the like corresponding to the same reference may be simply rephrased, or may be rephrased with a superordinate concept or a subordinate concept name.

  In the autonomous traveling system, one or a plurality of work vehicles are autonomously traveled in a work area and a non-work area to execute all or part of the work. In this embodiment, a tractor will be described as an example of a work vehicle. However, as a work vehicle, in addition to a tractor, a padded work machine such as a rice transplanter, a combiner, a civil engineering / construction work device, a snowplow, a walking work A machine is also included. In this specification, autonomous traveling means that the configuration related to traveling provided by the tractor is controlled by a control unit (ECU) provided in the tractor, and the tractor travels along a predetermined route. This means that the control unit included in the tractor controls the configuration related to the work included in the tractor, and the tractor performs the work along a predetermined route. In addition, the case where a person is on the tractor and the case where no person is on the tractor are included during autonomous running and autonomous work. On the other hand, manual running / manual work means that each component provided in the tractor is operated by the user to run / work.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an overall configuration of a robot tractor 1 provided in an autonomous traveling system 99 according to an embodiment of the present invention. FIG. 2 is a plan view of the robot tractor 1. FIG. 3 is a diagram showing the wireless communication terminal 46 provided in the autonomous traveling system 99 according to the embodiment of the present invention. FIG. 4 is a block diagram showing the main configuration of the control system of the robot tractor 1 and the wireless communication terminal 46.

  As shown in FIG. 1, a robot tractor (work vehicle) 1 provided in an autonomous traveling system 99 according to an embodiment of the present invention is operated by performing wireless communication with a wireless communication terminal 46. It is a vehicle. When the user operates the wireless communication terminal 46 and appropriately exchanges signals with the control unit 4 of the tractor 1, the tractor 1 can autonomously travel and work.

  First, a robot tractor (hereinafter sometimes simply referred to as “tractor”) 1 provided in an autonomous traveling system 99 according to an embodiment of the present invention will be described mainly with reference to FIGS. 1 and 2. .

  The tractor 1 includes a traveling machine body (body portion) 2 capable of autonomously traveling in a farm field (traveling area). A work machine 3 shown in FIGS. 1 and 2 is detachably attached to the traveling machine body 2. Examples of the work machine 3 include various work machines such as a tillage machine, a plow, a fertilizer machine, a mowing machine, and a seeding machine, and a desired work machine 3 is selected from these as required. 2 can be attached. The traveling machine body 2 is configured to be able to change the height and posture of the attached work machine 3.

  The configuration of the tractor 1 will be described in more detail with reference to FIGS. 1 and 2. As shown in FIG. 1, the traveling body 2 of the tractor 1 is supported at its front by a pair of left and right front wheels (wheels) 7 and 7 and at its rear by a pair of left and right rear wheels 8 and 8. Yes.

  A bonnet 9 is disposed at the front of the traveling machine body 2. The bonnet 9 houses an engine 10 and a fuel tank (not shown) that are driving sources of the tractor 1. Although this engine 10 can be comprised, for example with a diesel engine, it is not restricted to this, For example, you may comprise with a gasoline engine. Further, as a drive source, an electric motor may be used in addition to or instead of the engine.

  A cabin 11 for a user to board is disposed behind the hood 9. Inside the cabin 11, there are mainly provided a steering handle 12 for a user to steer, a seat 13 on which a user can be seated, and various operation devices for performing various operations. However, the work vehicle is not limited to the one with the cabin 11 and may be one without the cabin 11.

  As the above operation device, the monitor device 14 shown in FIG. 2, the throttle lever 15, the main transmission lever 27, the plurality of hydraulic operation levers 16, the PTO switch 17, the PTO transmission lever 18, the auxiliary transmission lever 19, and the work equipment lift switch 28 etc. can be mentioned as an example. These operating devices are arranged in the vicinity of the seat 13 or in the vicinity of the steering handle 12.

  The monitor device 14 is configured to display various information of the tractor 1. The throttle lever 15 is an operating tool for setting the output rotational speed of the engine 10. The main transmission lever 27 is an operating tool for changing the traveling speed of the tractor 1 in a stepless manner. The hydraulic operation lever 16 is an operation tool for switching and operating a hydraulic external take-off valve (not shown). The PTO switch 17 is an operating tool for switching the transmission / cutoff of power to a PTO shaft (power take-off shaft) (not shown) protruding from the rear end of the transmission 22. That is, when the PTO switch 17 is in the ON state, power is transmitted to the PTO shaft and the PTO shaft rotates to drive the work implement 3, while when the PTO switch 17 is in the OFF state, the power to the PTO shaft is cut off. Thus, the PTO shaft does not rotate and the work machine 3 is stopped. The PTO speed change lever 18 is used to change the power input to the work machine 3, and specifically, is an operating tool for changing speed of the rotational speed of the PTO shaft. The auxiliary transmission lever 19 is an operating tool for switching the gear ratio of the traveling auxiliary transmission gear mechanism in the transmission 22. The work implement raising / lowering switch 28 is an operating tool for raising and lowering the height of the work implement 3 attached to the traveling machine body 2 within a predetermined range.

  As shown in FIG. 1, a chassis 20 of the tractor 1 is provided at the lower part of the traveling machine body 2. The chassis 20 includes a body frame 21, a transmission 22, a front axle 23, a rear axle 24, and the like.

  The body frame 21 is a support member at the front portion of the tractor 1 and supports the engine 10 directly or via a vibration isolation member. The transmission 22 changes the power from the engine 10 and transmits it to the front axle 23 and the rear axle 24. The front axle 23 is configured to transmit the power input from the transmission 22 to the front wheels 7. The rear axle 24 is configured to transmit the power input from the transmission 22 to the rear wheel 8. When the front wheel 7 and the rear wheel 8 rotate in the forward direction, the tractor 1 moves forward. As the front wheel 7 and the rear wheel 8 rotate in the reverse direction, the tractor 1 moves backward.

  As shown in FIG. 4, the tractor 1 includes a control unit 4 for controlling the operation of the traveling machine body 2 (forward, reverse, stop, turn, etc.) and the operation of the work machine 3 (elevation, drive, stop, etc.). . The control unit 4 includes a CPU, a ROM, a RAM, an I / O, and the like (not shown), and the CPU can read various programs from the ROM and execute them. The controller 4 is electrically connected to a controller for controlling each component (for example, the engine 10 and the like) included in the tractor 1 and a wireless communication unit 40 that can wirelessly communicate with other wireless communication devices. ing.

  As the above controller, the tractor 1 includes at least an unillustrated engine controller, vehicle speed controller, steering controller, and elevator controller. Each controller can control each component of the tractor 1 in accordance with an electrical signal from the control unit 4.

  The engine controller controls the rotational speed of the engine 10 and the like. Specifically, the engine 10 is provided with a governor device 41 including an unillustrated actuator that changes the rotational speed of the engine 10. The engine controller can control the rotational speed of the engine 10 by controlling the governor device 41. Further, the engine 10 is provided with a fuel injection device 45 that adjusts the injection timing / injection amount of fuel to be injected (supplied) into the combustion chamber of the engine 10. The engine controller can stop the supply of fuel to the engine 10 and stop the driving of the engine 10 by controlling the fuel injection device 45, for example.

  The vehicle speed controller controls the vehicle speed of the tractor 1. Specifically, the transmission 22 is provided with a transmission 42 which is, for example, a movable swash plate type hydraulic continuously variable transmission. The vehicle speed controller can change the gear ratio of the transmission 22 and change to the desired vehicle speed by changing the angle of the swash plate of the transmission 42 with an actuator (not shown).

  The steering controller controls the turning angle of the steering handle 12. Specifically, a steering actuator 43 is provided in the middle of the rotating shaft (steering shaft) of the steering handle 12. In this configuration, when the tractor 1 travels along a predetermined route, the control unit 4 calculates and obtains an appropriate rotation angle of the steering handle 12 so that the tractor 1 travels along the route. A control signal is output to the steering controller so that the rotation angle is obtained. The steering controller drives the steering actuator 43 based on the control signal input from the control unit 4 and controls the rotation angle of the steering handle 12.

  The elevation controller controls the elevation of the work machine 3. Specifically, the tractor 1 includes an elevating actuator 44 composed of a hydraulic cylinder or the like in the vicinity of a three-point link mechanism that connects the work machine 3 to the traveling machine body 2. With this configuration, the lift controller drives the lift actuator 44 based on the control signal input from the control unit 4 to appropriately lift and lower the work implement 3 so that the work implement 3 performs farm work at a desired height. It can be carried out. By this control, the work machine 3 can be supported at a desired height such as a retreat height (a height at which farm work is not performed) and a work height (a height at which farm work is performed).

  Note that the plurality of controllers (not shown) control each part of the engine 10 and the like based on a signal input from the control part 4, so that the control part 4 substantially controls each part. I can grasp it.

  The tractor 1 including the control unit 4 as described above controls various parts of the tractor 1 (the traveling machine body 2, the work implement 3, etc.) by the control unit 4 when the user gets into the cabin 11 and performs various operations. Thus, the farm work can be performed while traveling in the field. Further, the tractor 1 can perform autonomous traveling and autonomous work based on a predetermined control signal output from the wireless communication terminal 46 in a state where the user is or is not riding on the tractor 1. It has become.

  Specifically, as shown in FIG. 4 and the like, the tractor 1 has various configurations for enabling autonomous traveling and autonomous work. For example, the tractor 1 includes a positioning antenna 6 and the like necessary for acquiring position information of itself (the traveling machine body 2) based on the positioning system. With such a configuration, the tractor 1 can acquire its own position information based on the positioning system and can autonomously travel on the field.

  Next, the configuration of the tractor 1 for enabling autonomous traveling will be described in more detail. Specifically, as shown in FIG. 4 and the like, the tractor 1 of the present embodiment includes a positioning antenna 6, a wireless communication antenna 48, a front camera 56, a rear camera 57, a storage unit 55, a vehicle speed sensor 53, and a rudder. An angle sensor 52 and the like are provided. In addition to these, the tractor 1 is provided with an inertial measurement unit (IMU) that can specify the posture (roll angle, pitch angle, yaw angle) of the traveling machine body 2.

  The positioning antenna 6 receives a signal from a positioning satellite constituting a positioning system such as a satellite positioning system (GNSS). As shown in FIG. 1, the positioning antenna 6 is attached to the upper surface of the roof 92 of the cabin 11 of the tractor 1. The positioning signal received by the positioning antenna 6 is input to a position information acquisition unit 49 as a position detection unit shown in FIG. The position information acquisition unit 49 calculates and acquires the position information of the traveling machine body 2 (strictly speaking, the positioning antenna 6) of the tractor 1 as, for example, latitude / longitude information. The position information acquired by the position information acquisition unit 49 is input to the control unit 4 and used for autonomous traveling.

  In this embodiment, a high-accuracy satellite positioning system using the GNSS-RTK method is used. However, the present invention is not limited to this, and other positioning systems can be used as long as high-precision position coordinates can be obtained. Also good. For example, it is conceivable to use a relative positioning method (DGPS) or a geostationary satellite type satellite navigation augmentation system (SBAS).

  The wireless communication antenna 48 receives a signal from the wireless communication terminal 46 operated by the user or transmits a signal to the wireless communication terminal 46. As shown in FIG. 1, the radio communication antenna 48 is attached to the upper surface of a roof 92 provided in the cabin 11 of the tractor 1. A signal from the wireless communication terminal 46 received by the wireless communication antenna 48 is subjected to signal processing by the wireless communication unit 40 shown in FIG. 4 and then input to the control unit 4. A signal transmitted from the control unit 4 or the like to the wireless communication terminal 46 is subjected to signal processing by the wireless communication unit 40, then transmitted from the wireless communication antenna 48 and received by the wireless communication terminal 46.

  The front camera 56 photographs the front of the tractor 1. The rear camera 57 captures the rear of the tractor 1. The front camera 56 and the rear camera 57 are attached to the roof 92 of the tractor 1. The moving image data captured by the front camera 56 and the rear camera 57 is transmitted from the wireless communication antenna 48 to the wireless communication terminal 46 by the wireless communication unit 40. The wireless communication terminal 46 that has received the moving image data displays the content on the display 37.

  The vehicle speed sensor 53 detects the vehicle speed of the tractor 1 and is provided, for example, on the axle between the front wheels 7 and 7. The detection result data obtained by the vehicle speed sensor 53 is signal-processed by the wireless communication unit 40, transmitted from the wireless communication antenna 48 and received by the wireless communication terminal 46, and the contents thereof are displayed on the display 37. The The steering angle sensor 52 is a sensor that detects the steering angle of the front wheels 7 and 7. In the present embodiment, the rudder angle sensor 52 is provided on a king pin (not shown) provided on the front wheels 7 and 7. Data of detection results obtained by the steering angle sensor 52 is output to the control unit 4. The steering angle sensor 52 may be provided in the steering handle 12.

  The storage unit 55 stores a travel route for autonomously traveling the tractor 1 and a work route for autonomously working, and stores a transition (travel locus) of the position of the tractor 1 (strictly speaking, the positioning antenna 6) during autonomous travel. Memory. In addition, the storage unit 55 stores various information necessary for the tractor 1 to autonomously travel and work.

  As shown in FIG. 3, the wireless communication terminal 46 is configured as a tablet personal computer including a touch panel 39. The user can check the information displayed on the display 37 of the wireless communication terminal 46 (for example, information from the front camera 56, the rear camera 57, a vehicle speed sensor, etc.). In addition, the user operates the hardware key 38 or the like disposed in the vicinity of the touch panel 39 or the display 37 and controls the control unit 4 of the tractor 1 to control signals (for example, temporarily). Stop signal, etc.). Note that the wireless communication terminal 46 is not limited to a tablet-type personal computer, and may be configured by, for example, a notebook-type personal computer instead.

  The tractor 1 configured as described above performs farm work by the work implement 3 along the work path P1 while traveling along the travel path P on the farm field based on an instruction of the user using the wireless communication terminal 46. Can do.

  Specifically, the user performs various settings using the wireless communication terminal 46, so that a linear or broken line work path P1 for performing farm work and an arcuate turning circuit that connects the ends of the work path P1 to each other. It is possible to generate a travel route (path) P as a series of routes that alternately connect (non-work route on which the tractor 1 turns) P2 (see FIG. 6). Then, the information on the travel route (work route P1 and non-work route P2) P generated in this way is input (transferred) to the storage unit 55 electrically connected to the control unit 4 of the tractor 1 and is transmitted in a predetermined manner. By performing the operation, the control unit 4 controls the tractor 1 so that the tractor 1 can autonomously travel along the travel route P and can be autonomously operated by the work implement 3 along the work route P1.

  Hereinafter, the configuration of the wireless communication terminal 46 will be described in more detail with reference to FIGS. 3 to 6. FIG. 5 is a diagram illustrating a display example of the monitoring screen 100 on the display 37 of the wireless communication terminal 46. FIG. 6 is a schematic diagram illustrating an example of an autonomous traveling route generated by the wireless communication terminal.

  As shown in FIGS. 3 and 4, the wireless communication terminal 46 according to the present embodiment includes a display 37, a hardware key 38, and a touch panel 39, as well as a display control unit 31 and a storage unit 32. , An agricultural field acquisition unit 33, a work area acquisition unit 34, a travel route acquisition unit 35, and the like.

  Specifically, the wireless communication terminal 46 is configured as a computer as described above, and includes a CPU, a ROM, a RAM, and the like. The ROM stores an appropriate program for causing the tractor 1 to perform autonomous traveling and autonomous work. By cooperation of this software and hardware, the wireless communication terminal 46 can be operated as the display control unit 31, the storage unit 32, the field acquisition unit 33, the work area acquisition unit 34, the travel route acquisition unit 35, and the like.

  The display control unit 31 creates display data to be displayed on the display 37 and appropriately controls display contents. For example, the display control unit 31 displays the monitoring screen 100 illustrated in FIG. 5 on the display 37 while the tractor 1 is autonomously traveling along the work route P1 while autonomously traveling along the travel route P.

  The storage unit 32 stores information on the tractor 1 and information on the farm field that are input by the user operating the touch panel 39 of the wireless communication terminal 46, and the created travel route P (work route P1 and non-work route P2). ) And the like.

  The farm field acquisition part 33 memorize | stores the position and shape of the farm field (running area | region) used as the object which the tractor 1 performs autonomous running and autonomous work. The position and shape of the field are obtained by, for example, driving the user to ride on the tractor 1 and making one turn along the outer periphery of the field, and recording the transition of the position information of the positioning antenna 6 at that time. can do. The position and shape of the field acquired by the field acquisition unit 33 are stored in the storage unit 32 as field information.

  The work area acquisition unit 34 sets the position of the work area where the tractor 1 is disposed in the field where the autonomous traveling is performed and where the farm work is performed. If demonstrating it concretely, in the radio | wireless communication terminal 46 of this embodiment, it is comprised by the predetermined operation so that the width of a headland and the width of a non-cultivated land can be set. And the non-working area consisting of the headland and the non-cultivated land is determined based on the above setting content and the position and shape of the field acquired by the field acquiring unit 33, and the non-working area is determined from the field of the field. An area excluding is defined as a work area.

  The travel route acquisition unit 35 alternately connects a work route P1 where the tractor 1 autonomously performs farm work in the field and a non-work route (rotation circuit) P2 connecting the ends of the work route P1. P is generated and acquired. When the user inputs information necessary for generating the travel route P using the touch panel 39 or the like, the travel route acquisition unit 35 automatically creates the travel route P (the work route P1 and the non-work route P2) based on the information. . The travel route P is generated so that the work route P1 that is linear or broken line is included in the work region, and the non-work route (turning circuit) P2 is included in the non-work region such as a headland. The travel route P generated by the travel route acquisition unit 35 is stored in the storage unit 32.

  The user appropriately operates the wireless communication terminal 46 to input (transfer) the information on the travel route P generated by the travel route acquisition unit 35 to the storage unit 55 of the tractor 1. Thereafter, the user gets on the tractor 1 and operates to place the tractor 1 at the start position of the travel route P. Subsequently, the user gets off the tractor 1 and operates the wireless communication terminal 46 to instruct the start of autonomous running / autonomous work. As a result, the control unit 4 controls the traveling and farming of the tractor 1 so that the tractor 1 performs farming along the work path P1 while traveling along the traveling path P.

  With the start of autonomous running / autonomous work, the display screen of the display 37 is switched to the monitoring screen 100 shown in FIG.

  On the left side of the monitoring screen 100, a front camera display unit 101 and a rear camera display unit 102 that display data transmitted from the front camera 56 and the rear camera 57 as moving image data are arranged vertically. On the right side of the monitoring screen 100, a work state display unit 103 that graphically shows the travel route P and the current position of the tractor 1 in a drawing or the like is arranged. A vehicle speed display unit 106 that displays the current vehicle speed of the tractor 1 is provided above the front camera display unit 101. The vehicle speed display unit 106 displays the current vehicle speed of the tractor 1 acquired based on the data transmitted from the vehicle speed sensor described above.

  Next, the control related to the change in the rudder angle at the time of switching between forward and backward travel during autonomous traveling will be described with reference to FIGS. FIG. 7 is a schematic diagram for explaining the flow when turning while switching forward and backward. FIG. 8 is a schematic diagram showing the determination angle θ when the neutral angle is set as a reference angle. FIG. 9 is a flowchart showing a process related to a change in the steering angle at the time of forward / reverse switching.

  First, a situation in which forward / reverse switching is performed during autonomous traveling will be described. For example, when the interval between the work paths P1 is narrow and the turn by only the forward movement of the tractor 1 cannot reach the next work path P1, the turn is performed by switching between forward and backward travel. More specifically, first, as shown in the leftmost diagram of FIG. 7, the vehicle is moved forward by approximately 90 ° toward the next work path P1 (first step), and then reversely moved as shown in the center diagram of FIG. Then, as shown in the rightmost drawing of FIG. 7, the vehicle is turned to advance to the target work path P1 (third process). The turning angle in the first step is not limited to approximately 90 °.

  Here, in order to shorten the time required for turning, it is preferable that the switching time when switching from the first process to the second process and the switching time when switching from the second process to the third process are short. However, when the first step is completed, the steering angle may not be a neutral angle as shown in FIG. Further, in the second step, it is assumed that the vehicle travels backward with the rudder angle as a neutral angle. Here, when the tractor 1 is stopped and the steering angle is returned to the neutral angle at the time of switching from the first process to the second process (that is, when switching between the forward and backward movements), the switching time from the first process to the second process. (That is, the stop time of the tractor 1) becomes long, and the forward / reverse switching is not smoothly performed.

  In this regard, in the present embodiment, the forward / reverse switching can be smoothly performed by performing the control shown in FIG. This will be specifically described below. The control unit 4 determines whether or not it is a forward / reverse switching timing (S101), and determines that it is a forward / backward switching timing (for example, between the first step and the second step, between the second step and the third step). And the steering angle (determination angle) is determined to be equal to or smaller than the first angle (S102). In the present embodiment, the neutral angle is set as a reference angle, and the rudder angle with respect to the neutral angle is set as a determination angle (an angle used in the determination process of FIG. 9 and the like). As shown in the modification, a reference angle other than the neutral angle may be used. The first angle is, for example, 10 ° (10 ° in the left direction and 10 ° in the right direction).

  When it is determined that the steering angle (determination angle) is equal to or smaller than the first angle, the control unit 4 stops the tractor 1 and simultaneously switches forward and backward (S103). That is, the control unit 4 does not change the rudder angle while the tractor 1 is stopped when the rudder angle (determination angle) is equal to or smaller than the first angle. Thereafter, when there is a difference between the steering angle and the target angle, the control unit 4 changes the steering angle to the target angle (S104).

  On the other hand, when it determines with the steering angle (determination angle) being larger than a 1st angle, the control part 4 stops the tractor 1 (S105). Then, the control unit 4 changes the rudder angle to the second angle while the tractor 1 is stopped (S106). That is, when the steering angle (determination angle) is larger than the first angle, the control unit 4 changes the steering angle while the tractor 1 is stopped. However, in order to shorten the stop time of the tractor 1, the control unit 4 changes the steering angle so that the determination angle is not the neutral angle but the determination angle is the second angle. The second angle is a value smaller than the first angle, for example, 2 °.

  After changing the rudder angle to the second angle, the control unit 4 switches between forward and backward travel (S106). Thereafter, the control unit 4 changes the steering angle to the target angle (S104).

  As described above, the tractor 1 can be stopped for a short time by changing the rudder angle after the forward / reverse switching, not during the stop of the tractor 1, so that the forward / backward switching can be performed smoothly. That is, in the present embodiment, the forward / reverse travel can be switched even if the rudder angle is other than the non-neutral angle. Furthermore, when the rudder angle at the time of stop is large, the rudder angle is changed to some extent (up to the second angle) while the tractor 1 is stopped. It is possible to prevent the corner from being changed. Since it is possible to prevent the rudder angle from being significantly changed after the forward / reverse switching, the fluctuations before and after the forward / backward switching can be reduced and the deviation of the route can be reduced.

  In step S106, the rudder angle may be changed to a neutral angle, or the rudder angle may be changed to a first angle. In the present embodiment, the process of step S102 is performed before the tractor 1 is stopped, but may be performed while the tractor 1 is stopped. In this case, the first line of step S103 and step S105 are unnecessary.

  Moreover, as shown in FIG. 10, the tractor 1 of this embodiment has the positioning antenna 6 disposed at a position (front position) deviated from the center of the tractor 1 in the front-rear direction. Therefore, when moving forward, the position in the forward direction than the center of the tractor in the front-rear direction is used as the current position, while in reverse, the position on the opposite side of the tractor in the forward direction is used as the current position. Will be. Therefore, there is a possibility that the autonomous running control method needs to be different between forward travel and reverse travel.

  Considering this, in the present embodiment, the calculation method of the current position of the tractor 1 is made different during reverse travel. That is, as shown in FIG. 10, the position of the positioning antenna 6 is virtually corrected so that the positioning antenna 6 is located at a symmetrical position with the line passing through the center of the tractor 1 as a symmetric line during reverse travel. As an actual process, a distance L in the front-rear direction from the center in the front-rear direction of the tractor 1 to the positioning antenna 6 is stored in advance, and when moving backward, from the detected current position to the rear direction of the tractor 1. A value offset by twice the distance L is handled as the current position. Thereby, the control method of autonomous running can be made the same at the time of advance and reverse.

  In the turning method shown in FIG. 7, the steering angle may not be a neutral angle when the first step is completed, but basically the steering angle is considered to be a neutral angle when the second step is completed. It is done. That is, since the forward / reverse switching is performed between the second step and the third step, the process of FIG. 9 is performed, but the steering angle change at the time of the forward / reverse switching is not necessary and is not performed. Therefore, in this turning direction, when switching from forward to reverse, forward / reverse switching is performed without a neutral angle. On the other hand, by using the control of the present embodiment, for example, in the turning method shown in FIG. 11, when switching from backward to forward, it is possible to switch between forward and backward without a neutral angle.

  The turning method of FIG. 11 is used when the normal turning method or the turning method of FIG. 7 cannot be used due to, for example, the obstacle A. Specifically, first, as shown in the leftmost diagram of FIG. 11, the tractor 1 is turned in one direction (left direction) while moving forward (first step). Thereafter, as shown in the second drawing from the left in FIG. 11, the tractor 1 is turned in the other direction (right direction) while moving forward (second step). Thereafter, as shown in the second drawing from the right in FIG. 11, the vehicle is turned by approximately 90 ° while moving backward (third step), and then is turned forward to the next work path P1 as shown in the rightmost drawing of FIG. 11 ( (4th process). The turning angle in the third step is not limited to 90 °. Although the tractor 1 is advanced in both the first step and the second step, the direction in which the tractor 1 is turned is different in the first step and the second step. The same processing as in FIG. 9 is also performed. That is, the control unit 4 advances the tractor 1 without changing the rudder angle during the stop or stops the tractor 1 based on the comparison result between the rudder angle (determination angle) and the first angle. Decide to change. Moreover, since it is preferable to stop immediately after turning in a 3rd process, a steering angle may not be a neutral angle in the stage which the 3rd process was completed. Therefore, when the turning method of FIG. 11 is used, the vehicle is switched from backward to forward in a state where the steering angle is not a neutral angle. Therefore, the control unit 4 performs the same process as in FIG. 9 between the second process and the third process. That is, based on the comparison result between the steering angle (determination angle) and the first angle, the control unit 4 stops the tractor 1 at the same time (without changing the steering angle) or stops the tractor 1. Decide whether to change the rudder angle during.

  Next, a first modification of the above embodiment will be described. FIG. 12 is a schematic diagram illustrating the determination angle θ when the target angle is set as a reference angle. In the description of the first modified example and the second modified example described later, the same or similar members as those in the above-described embodiment may be denoted by the same reference numerals in the drawings, and description thereof may be omitted.

  In the above embodiment, since the reference angle is a neutral angle, the rudder angle and the determination angle are the same. However, in the first modification, the reference angle is an angle other than the neutral angle. As the reference angle of the first modification, for example, the target angle of the rudder angle after switching between forward and backward travel can be used. Since the process related to the change in the steering angle at the time of forward / reverse switching performed in the first modification is the same as that of the present embodiment, the description thereof is omitted.

  Next, a second modification of the above embodiment will be described. FIG. 13 is a flowchart illustrating a process related to a change in the steering angle at the start of forward / reverse travel.

  In the above-described embodiment, the processing related to the change of the steering angle at the time of switching between the forward and backward travels has been described. However, the control unit 4 of the second modified example further performs the same processing regarding the change of the steering angle at the start of the forward and backward travel.

  This will be specifically described below. The control unit 4 determines whether or not it is the start timing of forward / reverse travel (S201), and when it is determined that it is the start timing of forward / backward travel, it determines whether or not the steering angle (determination angle) is equal to or smaller than the third angle (S202). . The third angle is a rudder angle that is a starting condition for forward / backward traveling by autonomous traveling, and the forward / backward movement cannot be started at a rudder angle larger than the third angle. The third angle is a value larger than the first angle, but may be a small value. The third angle is 15 °, for example, but may be another value between 10 ° and 20 °.

  When it is determined that the rudder angle is equal to or smaller than the third angle, the control unit 4 starts moving forward and backward without changing the rudder angle (S203). Thereafter, when there is a difference between the steering angle and the target angle, the control unit 4 changes the steering angle to the target angle (S204).

  On the other hand, if the control unit 4 determines that the rudder angle is larger than the third angle, the control unit 4 changes the rudder angle to the second angle without starting forward / rearward travel (S205). After changing the rudder angle to the second angle, the control unit 4 starts moving forward and backward (S206). Thereafter, the control unit 4 changes the steering angle to the target angle (S204).

  Similarly to the above embodiment, in step S205, the steering angle may be changed to a neutral angle, the steering angle may be changed to a target angle, or the steering angle may be changed to a first angle. Similarly to the first modification, the reference angle may be other than the neutral angle in the second modification.

  As described above, the tractor 1 of the present embodiment includes the wheels (the front wheels 7 and the rear wheels 8) and the control unit 4. The controller 4 controls the rotation direction of the rear wheels 8 and the steering angle that is the turning angle of the front wheels 7 along the travel route. When the rudder angle is a non-neutral angle, the control unit 4 can change the rotation direction of the rear wheel 8 from the forward direction to the reverse direction, or from the reverse direction to the forward direction.

  As a result, even when the rudder angle is a non-neutral angle, it is possible to switch from forward to reverse, or from reverse to forward, so that it is possible to smoothly switch back and forth.

  Moreover, in the tractor 1 of this embodiment, when the determination angle which is a steering angle with respect to the reference angle is equal to or less than the first angle, the control unit 4 does not change the steering angle while the rotation of the rear wheel 8 is stopped. The rotation direction of the rear wheel 8 can be changed from the forward direction to the reverse direction, or from the reverse direction to the forward direction.

  Thereby, if the determination angle is equal to or smaller than the predetermined first angle, the forward / reverse movement can be smoothly switched. In addition, by setting the first angle as a threshold value, it is possible to prevent the rudder angle from being significantly changed after the forward / reverse switching.

  In the tractor 1 of the present embodiment, the control unit 4 stops the rotation of the rear wheel 8 when the determination angle exceeds the first angle, and the determination angle is the first angle or the second smaller than the first angle. After changing the rudder angle to be an angle, if the rear wheel 8 is rotating in the forward direction, it is changed to the backward direction, and if the rear wheel 8 is rotating in the backward direction, it is changed to the forward direction.

  As a result, when the determination angle is large, the steering angle is changed after the stop, and the forward / reverse switching is performed. Therefore, the impact at the time of switching between the forward / reverse traveling can be reduced.

  In the tractor 1 of the present embodiment, the second angle is a non-neutral angle.

  Thereby, since the forward / reverse switching is performed without reaching the neutral angle, the forward / backward switching can be quickly performed.

  Moreover, in the tractor 1 of this embodiment, the control part 4 has a difference in a steering angle and a target angle after changing the rotation direction of the rear wheel 8 from the forward direction to the reverse direction or from the reverse direction to the forward direction. In this case, change the rudder angle to the target angle.

  Thereby, even when there is a difference between the rudder angle and the target angle, the rudder angle is changed after the forward / backward movement of the tractor 1 is switched, so that the forward / backward movement can be smoothly switched.

  The preferred embodiments and modifications of the present invention have been described above, but the above configuration can be modified as follows, for example.

  In the embodiment and the modification described above, the process of changing the rudder angle either during stoppage or after switching between forward and backward movements has been described, but the rudder angle is changed immediately before and after switching forward and backward. Alternatively, the steering angle may be changed immediately after the stop and the forward / reverse switching, or the steering angle may be changed immediately before and after the forward / reverse switching.

  In the above embodiment and the modified example, the wheel to be controlled for changing the rudder angle is the front wheel 7 and the wheel to be controlled in the rotational direction is the rear wheel 8. It may be. For example, in the case of front wheel drive or four wheel drive, the wheels to be controlled are the same in the two controls. Moreover, both the front wheel 7 and the rear wheel 8 may be the wheels to be controlled for changing the rudder angle.

1 Tractor (work vehicle)
4 Control part 7 Front wheel (wheel)

Claims (5)

In a work vehicle that autonomously travels along a predetermined travel route,
Wheels,
A control unit that controls the rotation direction of the wheel and the steering angle that is the turning angle of the wheel along the travel route;
With
When the rudder angle is a non-neutral angle, the control unit can change the rotation direction of the wheels from a forward direction to a reverse direction, or from a reverse direction to a forward direction. . The work vehicle according to claim 1,
When the determination angle that is the steering angle with respect to the reference angle is equal to or less than the first angle, the control unit changes the rotation direction of the wheel from the forward direction to the reverse direction without changing the steering angle while the rotation of the wheel is stopped. Alternatively, the work vehicle can be changed from a reverse direction to a forward direction. The work vehicle according to claim 2,
The control unit stops the rotation of the wheel when the determination angle exceeds the first angle, and sets the steering angle so that the determination angle becomes the first angle or a second angle smaller than the first angle. After the change, the work vehicle is changed to the reverse direction when the wheel is rotating in the forward direction, and is changed to the forward direction when the wheel is rotating in the reverse direction. The work vehicle according to claim 3,
The work vehicle, wherein the second angle is a non-neutral angle. A work vehicle according to any one of claims 1 to 4,
The control unit changes the steering angle to the target angle when there is a difference between the steering angle and the target angle after changing the rotation direction of the wheel from the forward direction to the reverse direction or from the reverse direction to the forward direction. A working vehicle characterized by

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