Control device

Abstract

This invention provides a control device capable of eliminating idling in a work vehicle. In one embodiment, when a work vehicle operating in a field makes a turn to move to the next work site, the control device calculates the ratio of the rotational speeds of the left and right wheels of the work vehicle. If this ratio deviates from a predetermined value from a reference value, idling is detected. The control device includes a position acquisition device that acquires the current position and orientation of the work vehicle. In the event of idling, the device detects whether the idling has been eliminated based on whether the position acquired by the position acquisition device has changed.

Description

[Technical Field]

[0001] This application is a divisional application of the invention patent application filed on February 18, 2022, with application number 111105982 and entitled "Control Device". The present invention relates to a control device. [Previous Technology]

[0002] Conventionally, control devices are known that control an operating device based on the location information of a work vehicle in a field, thereby enabling the work vehicle to move autonomously (for example, see Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-24541 [Summary of the Invention]

[0004] [Problem to be solved by the invention] However, in the prior art, there is room for improvement in eliminating the idling state of the wheels of the work vehicle.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide a control device capable of eliminating the idling state of a working vehicle. [Means for solving the problem]

[0006] To solve the above problems and achieve the objective, in one embodiment of the control device 100, when a work vehicle 1 operating in a field makes a turn for transferring to the next project, the ratio of the rotational speeds of the left and right wheels of the work vehicle 1 is calculated. If the ratio deviates from a predetermined value from a reference value, a wheel idling state is detected. The control device includes a position acquisition device 150, which acquires the current position and orientation of the work vehicle 1. In the case of wheel idling, the idling state of the wheels is detected by whether the position acquired by the position acquisition device 150 has changed. [Effects of the Invention]

[0007] According to one embodiment, the idling state of the work vehicle can be eliminated.

Implementation Method

[0009] (Overview of the work vehicle) First, the overview of the work vehicle 1 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a side view of the work vehicle 1. Figure 2 is a top view of the work vehicle 1.

[0010] In addition, in the following description, the front-to-back direction is the direction of travel of the work vehicle 1 when it is traveling in a straight line. The front side of the direction of travel is defined as "front" and the rear side is defined as "rear". The direction of travel of the work vehicle 1 is the direction from the driver's seat 41 toward the steering wheel 35 (steering device) when traveling in a straight line (refer to Figures 1 and 2).

[0011] The left and right directions are horizontally orthogonal to the front and back directions, and are defined as the "front" side. That is, when the operator (also known as the worker) is sitting in the control seat 41 facing forward, the left side is "left" and the right side is "right".

[0012] The up-down direction is the vertical direction. The front-back, left-right, and up-down directions are orthogonal to each other. These directions are defined for ease of explanation, and the present invention is not limited by these directions.

[0013] In this embodiment, the work vehicle 1 will be described as a passenger-type seedling transplanter 1 that has a seedling planting section 4 as a field work device and receives seedlings in the field. As shown in Figures 1 and 2, the seedling transplanter 1 has a seedling planting section 4 that can be raised and lowered for planting seedlings in the field, which is provided on the rear side of the vehicle body 2 via a lifting linkage mechanism 3.

[0014] The main body of the fertilizer applicator 5 is arranged on the upper rear side of the vehicle body 2. In addition, when the working vehicle 1 is not a seedling transplanter 1, it may sometimes be equipped with a seeding device or the like as a working device.

[0015] The vehicle body 2 is a four-wheel drive vehicle having left and right front wheels 10 and rear wheels 11 as wheels, i.e., drive wheels. A gearbox 13 that transmits driving force to the seedling planting section 4 and the like is provided on the front side of the main frame 15 that constitutes the vehicle body 2. A hydraulic continuously variable transmission 14 that outputs the driving force supplied by the engine 30, i.e., the rotation generated by the engine 30, to the gearbox 13 is provided.

[0016] The continuously variable transmission 14 is a hydrostatic continuously variable transmission known as HST (Hydraulic Static Transmission). The following explanation addresses the case where the continuously variable transmission is HST 14.

[0017] An auxiliary transmission mechanism 16 is provided within the gearbox 13. This auxiliary transmission mechanism 16 switches the driving mode of the vehicle body 2, such as when driving on the road in high-speed mode and when transplanting seedlings in low-speed mode. Front wheel end boxes 10a are provided on the left and right sides of the gearbox 13. Front wheels 10 are mounted on the left and right front axles 10b, which protrude outward from the front wheel support portion, which allows the operation direction of the left and right front wheel end boxes 10a to be changed.

[0018] In addition, on the rear side of the main frame 15, rear wheel gearboxes 11a are installed on the left and right sides of the horizontally arranged rear frame 22 (refer to Figure 2), and rear wheels 11 are installed on the left and right rear axles 11b that protrude outward from the rear wheel gearboxes 11a respectively.

[0019] Furthermore, the left and right linkage support frames 23 that support the lifting linkage mechanism 3 are projecting upwards onto the upper part of the rear frame 22. A pair of lower linkage arms 24 are provided on the lower side of the left and right linkage support frames 23 and between the left and right sides. A lifting cylinder 25 that is operated by hydraulic pressure is provided between the left and right lower linkage arms 24.

[0020] An upper connecting arm 26 is provided above the lifting cylinder 25, forming a lifting linkage mechanism 3 as a parallel linkage mechanism. In addition, the other ends of the left and right lower connecting arms 24, the lifting cylinder 25, and the upper connecting arm 26, which are respectively connected to the sides of the traveling vehicle body 2, are mounted on the front of the seedling planting section 4.

[0021] In addition, an engine 30 is mounted on the main frame 15. The rotational power of the engine 30 is transmitted to the gearbox 13 via the belt drive 21 and HST 14. The rotational power transmitted to the gearbox 13 is divided into driving power and external extraction power after being changed by the auxiliary transmission mechanism 16 in the gearbox 13.

[0022] In addition, the rotational power of the engine 30 is transmitted to a hydraulic pump (not shown). The hydraulic pressure generated by the hydraulic pump is supplied to the HST 14, the power steering mechanism 88 of the steering wheel 35 (see Figure 3), the lifting cylinder 25, etc.

[0023] The external extraction power, which is taken out from the rotational power transmitted to the gearbox 13, is transmitted to the insertion clutch box 27 located at the rear of the vehicle body 2, and from the insertion clutch box 27 to the seedling insertion section 4 via the insertion drive shaft 67.

[0024] On the other hand, left and right drive shafts 42 are provided at the rear of the gearbox 13. Rotational power from the engine 30 is transmitted to the left and right rear wheel gearboxes 11a via the gearbox 13 and drive shafts 42.

[0025] In addition, a side clutch 44 for engaging and disengaging power transmission to the left and right drive shafts 42 is provided on the upstream side of the left and right drive shafts 42 in the transmission direction (see Figure 3). As shown in Figure 1, a side clutch pedal 43a for engaging and disengaging the left and right side clutches 44 is provided on the lower front side and on the left and right side of the control seat 41.

[0026] When the side clutch pedal 43a on the inside of the left and right side clutch pedals 43a is pressed and the side clutch 44 is disengaged, the steering wheel 35 is operated to turn, and the drive rotation of the rear wheel 11 on the inside of the turn can be completely cut off.

[0027] A hood 39 is provided on the upper front side of the vehicle body 2, and an operation panel 38 for operating various parts is arranged on the upper part of this hood 39. A monitor 86 (see Figure 3) and the like are provided on the operation panel 38.

[0028] In addition, the hood 39 is provided with a steering wheel 35 for turning the vehicle body 2, a gear shift lever 36 for operating the HST 14 and the seedling planting section 4, and a secondary gear shift lever 37 for operating the secondary gear shift mechanism 16.

[0029] Furthermore, a front cover 40 that can be opened and closed is provided on the front side of the hood 39. Inside the front cover 40 are a fuel tank, a battery, and a linkage mechanism that rotates the lower sides of the left and right front wheels 10 and the left and right front wheel end boxes 10a when the steering wheel 35 is turned. The front wheels 10 are, for example, steering wheels that turn according to the steering wheel 35.

[0030] An engine cover 30a is provided on the rear side of the engine cover 39 and above the engine 30, covering the upper and side parts of the engine 30. An operator's seat 41 is provided on the upper part of the engine cover 30a for the operator to sit on.

[0031] A fertilizer applicator 5 is provided on the rear side of the control seat 41 and the rear end side of the main frame 15. The driving force of the fertilizer applicator 5 is transmitted by a fertilizer transmission mechanism, which is configured to face the fertilizer applicator 5 from the left and right sides of the left and right rear wheel gearboxes 11a.

[0032] The lower left and right sides of the engine hood 30a and the engine hood 39 are provided with roughly horizontal footboards 33. As shown in Figure 2, part of the footboards 33 are grid-shaped, so that even if the mud attached to the operator's shoes or other items falls off the footboards 33, the mud or other items will fall onto the field.

[0033] Furthermore, as shown in Figure 2, a rear pedal 330 is connected to the rear of the footplate 33. Preferably, the surface of the rear pedal 330 is provided with an anti-slip treatment, for example, forming a plurality of raised patterns, so that the foot is less likely to slip during operation.

[0034] In addition, a seedling rack 50 is provided on the front side and the left and right sides of the vehicle body 2. The seedling rack 50 is provided with multiple seedling carriers 52 on the seedling rack support 51 in a way that is spaced apart in the vertical direction. It can hold seedlings, fertilizer bags and other work materials to be added to the seedling planting part 4.

[0035] Furthermore, the seedling box 53, which holds the seedlings to be planted in the field, is assembled together with a sliding mechanism that allows it to slide in the left-right direction at the rear end of the lifting linkage mechanism 3. The seedling box 53 is provided with seedling dividers 54 that are longer in the vertical direction, spaced at predetermined intervals in the left-right direction. A seedling planting device 55 is provided below the seedling box 53 to grab the loaded seedlings and plant them in the field.

[0036] The seedling transplanting device 55 transplants seedlings simultaneously in eight rows, the same number as the number of transplanting rows divided by the seedling divider 54. Four transplanting transmission boxes 56 are arranged at intervals below the seedling box 53. Transplanting rotors 57 are installed on the left and right sides of the transplanting transmission boxes 56 respectively. While rotating, the transplanting rotors 57 use the planting rods 58 to pick up seedlings and transplant them into the field.

[0037] The fertilizer application device 5 divides the fertilizer hopper 70, which stores fertilizer, into the same number of working rows as the seedling transplanting section 4 (eight rows in the example shown in Figure 2). In addition, the eight-row fertilizer hopper 70 is longer in the left-right direction, so the convenience of fertilizer application and disassembly is reduced. Therefore, it is also possible to have a so-called side-fertilization structure in which the fertilizer hoppers divided into four rows are arranged side by side with each other.

[0038] At the lower part of the fertilizer hopper 70, a delivery device 71 for supplying fertilizer at a set amount is provided in each row. Below the delivery device 71, a ventilation duct 72 is provided in the left-right direction for conveying air to pass through, allowing the fertilizer to move. Below the delivery device 71, a fertilizer hose 73 is provided to guide the fertilizer to the vicinity of the seedling planting position of the seedling planting section 4. In addition, a blower 74 is provided at one end of the ventilation duct 72, which generates conveying air by being operated by a blower motor 76.

[0039] As shown in Figures 1 and 2, a central float 62C and two side floats 62L and 62R are provided below the seedling planting section 4, which can rotate freely around an axis and slide in contact with the field surface. In addition, the central float 62C and the left and right side floats 62L and 62R are sometimes collectively referred to as float 62.

[0040] Furthermore, below the seedling planting section 4, a leveling rotating body 63 is provided on the front side of the float 62 to level the unevenness of the field surface. In addition, the driving force is transmitted from the rear wheel gearbox 11a on the left and right sides to the leveling rotating body 63 via the rotating body drive shaft 63a.

[0041] Furthermore, as shown in Figure 1, marking devices 65 are respectively installed on the left and right sides of the seedling planting section 4. Either the left or right side of the marking device 65 contacts the field surface, forming a groove that serves as the driving target in the next work train (next project). When one side of the left and right marking devices 65 touches the ground, the other side separates upwards. When the seedling planting section 4 rises during a turn, both sides separate upwards together. When the seedling planting section 4 descends after a turn, one side separates upwards, and the other side touches the ground.

[0042] Furthermore, as shown in Figures 1 and 2, a center marker 66 that is longer in the vertical direction is provided at the left and right center of the vehicle body 2 and in front of the hood 39. By aligning the center marker 66 with the groove formed on the field by the left and right marking devices 65, it is possible to align the vehicle with the working position of the previous work train, thereby improving work accuracy and preventing non-working activities.

[0043] Furthermore, depending on the soil conditions of the field, sometimes the guide lines formed by the left and right marking devices 65 are immediately buried, and the target for straight-line movement disappears. In this case, left and right side marking devices 19, which are positioned in front of the left and right marking devices 65, can be used. That is, the left and right side marking devices 19 are moved outwards so that they are positioned above the seedlings to be planted, thereby enabling planting operations that are consistent with the planting of seedlings in the previous work row.

[0044] Furthermore, as shown in Figure 1, the seedling transplanter 1 has a position acquisition device 150. The position acquisition device 150 acquires the current position and orientation of the seedling transplanter 1. The position acquisition device 150 may include, for example, a positioning sensor, GPS (Global Positioning System), GNSS (Global Navigation Satellite System), or other positioning units. The position acquisition device 150 may also be composed of multiple devices. The position acquisition device 150 may also include a camera, an ultrasonic sensor, and may also acquire the turning position in the field and detect the distance to the turning position.

[0045] For example, the position acquisition device 150 receives positioning information from the positioning unit, generates current position and orientation information of the vehicle body 2 based on the received positioning information, and obtains the current position and orientation. The position acquisition device 150 is, for example, mounted on the mounting support 59 and positioned above the vehicle body 2.

[0046] The straight-line driving control program and the turning control program generated based on the position information from the position acquisition device 150 are stored in different locations. For example, the straight-line driving control program is stored in the straight-line driving control ECU (Electronic Control Unit) 100a within the position acquisition device 150, and the turning control program is stored, for example, in the turning control ECU 100b housed in the hood 39. Furthermore, the straight-line driving control ECU 100a and the turning control ECU 100b are included in the control device 100 described later (see Figure 3). The straight-line driving control ECU 100a and the turning control ECU 100b may also be stored in the same ECU.

[0047] (Control System of Seedling Transplanter) Next, the control system of seedling transplanter 1 will be described with reference to Figure 3. Figure 3 is a block diagram showing the control system centered on the control device 100 of seedling transplanter 1. Seedling transplanter 1 can control each part by means of electronic control and has a control device (hereinafter referred to as controller) 100 for controlling each part.

[0048] The controller 100 is equipped with a processing unit including a CPU (Central Processing Unit), a storage unit including ROM (Read Only Memory) and RAM (Random Access Memory), and an input / output unit. These units are interconnected and can exchange signals with each other. The storage unit stores computer programs and other data that control the seedling transplanter 1. The controller 100 performs various functions by reading the computer programs and other data stored in the storage unit.

[0049] The controller 100 is connected to actuators such as a throttle motor 80, hydraulic control valves 81 and 82, insert clutch operating solenoid 83, side clutch operating solenoid 84, HST motor 85, scribing lifting motor 87, steering motor 95 (motor), differential lock switching motor 96, etc.

[0050] The throttle motor 80 operates the throttle valve, which regulates the intake air volume of the engine 30, thereby increasing or decreasing the speed of the output shaft of the engine 30. The hydraulic control valve 81 controls the extension and retraction of the lifting cylinder 25. The hydraulic control valve 82 controls the power steering mechanism 88. The insert clutch operating solenoid 83 operates the insert clutch 27a.

[0051] The side clutch operating solenoid 84 causes the side clutch 44 to operate, and this side clutch 44 switches the power transmission state to the rear wheel 11 (refer to Figure 1). In addition, the side clutches 44 are respectively provided on the left and right rear wheels 11, and two side clutch operating solenoids 84 are provided corresponding to each side clutch 44.

[0052] The HST motor 85 changes the rotation angle of the trunnion of the HST 14, thereby changing the tilt angle of the swashplate of the HST 14. The steering motor 95 is a motor that, in the case of automatic cornering control, drives the steering device, i.e., the steering wheel 35, to adjust the steering amount (steering angle) of the front wheels 10 (refer to Figure 1). The steering motor 95 rotates the steering wheel 35. The lane marking lift motor 87 raises and lowers the lane marking 65.

[0053] The differential lock switching motor 96 is a motor that switches the operation and stop operation of the differential locking mechanism 97 (hereinafter referred to as the differential lock mechanism (same speed rotation mechanism)). The differential lock mechanism 97 locks the differential control that causes the left and right front wheels 10 (or rear wheels 11) to rotate at different speeds when turning. That is, by making the differential lock mechanism 97 active, the differential control is locked, and the left and right wheels rotate at the same speed.

[0054] The controller 100 is connected to a speed sensor 90, a steering amount sensor 91 (steering angle sensor), a tilt sensor 92, etc., which are used as detection devices. Four speed sensors 90 are provided corresponding to the left and right front wheels 10 and the rear wheels 11, respectively, to detect the speed of the left and right front wheels 10 and the rear wheels 11.

[0055] The steering amount sensor 91 detects the amount of operation of the steering wheel 35, which is a steering device, i.e., the amount of steering (steering angle) of the front wheels 10. The steering amount sensor 91 is, for example, installed on a shaft connected to the steering arm. In addition, the steering amount is detected in the left and right directions respectively, with the value when the steering wheel 35 is in a preset straight-line driving position as a reference value. The tilt sensor 92 detects the tilt angle of the vehicle body 2.

[0056] In addition, as operation signals, signals are input to the controller 100 from the gear shift lever 36, the auxiliary gear shift lever 37, the autonomous driving switch 46, the insertion part lifting switch 47, the automatic turning switch 48, the line marking automatic lifting switch 49, etc.

[0057] The autonomous driving switch 46 is a switch for toggling whether autonomous driving is performed. Specifically, the autonomous driving switch 46 is a switch for switching the driving mode to autonomous driving mode or manual driving mode.

[0058] The transplanting section lifting switch 47 is a switch that toggles whether the seedling transplanting section 4 is raised or lowered. The transplanting section lifting switch 47 is changed to the "raise" and "lower" positions.

[0059] When the planting section lifting switch 47 is in the "up" position, the seedling planting section 4 rises to a predetermined non-operating position, becoming a non-operating state where the seedling planting device 55 stops. When the planting section lifting switch 47 is in the "down" position, the seedling planting section 4 descends to a predetermined operating position, becoming an operating state where the seedling planting device 55 operates. That is, the planting section lifting switch 47 is a switch for detecting the operating state of the seedling planting section 4. Alternatively, a separate switch for detecting the operating state of the seedling planting section 4 may be provided.

[0060] The automatic raising / lowering switch 49 is a switch that toggles whether the automatic raising / lowering of the lane marker 65 is linked to the steering wheel 35's operating amount, i.e., the steering amount of the front wheels 10. When the automatic raising / lowering switch 49 is "ON", control is performed to automatically raise / lower the lane marker 65 in conjunction with the steering amount. On the other hand, when the automatic raising / lowering switch 49 is "OFF", control is not performed to automatically raise / lower the lane marker 65 in conjunction with the steering amount.

[0061] The automatic turn switch 48 is a switch that toggles whether or not automatic turning can be performed. When the automatic turn switch 48 is "on", automatic turning can be performed. When the automatic turn switch 48 is set to "off", automatic turning cannot be performed. When the automatic turn switch 48 is "off", automatic turning will not be performed even if the conditions for performing automatic turning are met.

[0062] Here, the functional structure of the controller 100 will be described using Figure 4. Figure 4 is a block diagram showing the functional structure of the controller 100.

[0063] As shown in Figure 4, the controller 100 includes a detection unit 101, an idle detection unit 102, a drive control unit 103, and a driving control unit 104.

[0064] The detection unit 101 detects the rotational speeds of the front wheel 10 and the rear wheel 11 during turning based on the detection results from the speed sensor 90. Specifically, when the steering angle of the front wheel 10 is above a predetermined angle, the detection unit 101 detects the rotational speeds of the left front wheel 10, the right front wheel 10, the left rear wheel 11, and the right rear wheel 11. In other words, when differential control is initiated, the detection unit 101 detects the rotational speeds of the front wheel 10 and the rear wheel 10.

[0065] The idle detection unit 102 detects the idle state of the front wheels 10 based on the difference in rotational speed between the left and right front wheels 10, i.e., the left-right difference. Specifically, as the left-right difference, the idle detection unit 102 calculates the ratio of the rotational speed of the right front wheel 10 to the rotational speed of the left front wheel 10. Alternatively, as the left-right difference, the idle detection unit 102 calculates the ratio of the rotational speed of the left front wheel 10 to the rotational speed of the right front wheel 10. Furthermore, the idle detection unit 102 may also calculate the left-right difference using the difference between the rotational speed of the left front wheel 10 and the rotational speed of the right front wheel 10.

[0066] Furthermore, when the ratio of the rotational speed difference between the left and right wheels deviates from a predetermined value by more than a reference value, the idle speed detection unit 102 detects an idle state. The reference value is set to a value corresponding to the steering angle of the front wheels 10. That is, when the ratio of the rotational speed deviates from the reference value by less than a predetermined value, the idle speed detection unit 102 detects that the turning is normal by differential control; when the ratio of the rotational speed deviates from the reference value by more than a predetermined value, it detects that one of the left or right front wheels 10 is in an idle state. In addition, when differential control is applied to the rear wheels 11, the idle speed detection unit 102 detects the idle state of the rear wheels 11.

[0067] Thus, the controller 100 according to the embodiment can detect the idling state by detecting the rotational speed of the left and right wheels (front wheel 10 or rear wheel 11), without obtaining the position information of the position acquisition device 150. That is, the controller 100 according to the embodiment can detect the idling state at low cost.

[0068] In addition, when both the left and right front wheels 10 are in an idling state, since the position detected by the position detection device 150 has not changed, the idling detection unit 102 detects that both the left and right front wheels 10 are in an idling state.

[0069] When the idle state is detected by the idle detection unit 102, the drive control unit 103 drives the differential lock switching motor 96 to make the differential lock mechanism 97 operate and thus become the engaged state.

[0070] Furthermore, when the differential lock mechanism 97 of the front wheel 10 is operated by the drive control unit 103, the idling detection unit 102 detects whether the idling state of the front wheel 10 has been eliminated based on the rotational speed of the rear wheel 11, which is the driven wheel (in the state where the clutch is disengaged from the drive shaft) during cornering. Specifically, if the rear wheel 11, which is the driven wheel, is detected to be rotating, the idling detection unit 102 detects that the idling state has been eliminated; if the rear wheel 11 is detected to be stopped, the idling detection unit 102 detects that the idling state continues.

[0071] In this way, when the front wheel 10 is in a free-spinning state, by operating the differential lock mechanism 97, the left and right front wheels 10 rotate at the same speed, thus enabling the elimination of the free-spinning state with high precision.

[0072] Furthermore, if the idling state of the front wheels 10 is not eliminated after the differential lock mechanism 97 of the front wheels 10 is operated by the drive control unit 103, the idling detection unit 102 switches the rear wheels 11 from driven wheels to drive wheels. Specifically, the idling detection unit 102 switches the rear wheels 11 to drive wheels by connecting a clutch to the drive shaft of the rear wheels 11. That is, even if the differential lock mechanism 97 is operated but the idling state of the front wheels 10 is not eliminated, the idling state can be eliminated with high precision by forcibly engaging four-wheel drive.

[0073] Alternatively, the system may be configured such that the functions of the detection unit 101, the idling detection unit 102, and the drive control unit 103 can be switched on and off via a switch (not shown). This switch may be located, for example, near the operator's seat 41 of the vehicle body 2.

[0074] Alternatively, the switch can be configured to be switched via a remote control that operates the seedling transplanter 1 remotely (for various adjustments of the operating machine) while the seedling transplanter 1 is in automatic operation. This remote control is also used for switching control of the seedling quantity, planting depth, and seedling track in the planting section 4.

[0075] Alternatively, the remote control can be used to control four-wheel drive regardless of whether there is an idling state. Or, when four-wheel drive is forcibly activated during idling or other situations, the four-wheel drive control can be deactivated (the rear wheel 11 can be switched from a drive wheel to a driven wheel).

[0076] In addition, the controller 100 can also determine whether the seedling transplanter 1 is moving (including whether it is idling) based on the position information detected by the position acquisition device 150.

[0077] The driving control unit 104 executes an autonomous driving mode in which the driving vehicle 2 performs operations while automatically driving (autonomous driving) based on the current position information of the driving vehicle 2 obtained from the position acquisition device 150.

[0078] (Autonomous Driving Mode) Here, referring to Figure 5, the autonomous driving (automatic driving) performed by the seedling transplanter 1, including automatic turning in the field, will be explained. Figure 5 is an explanatory diagram of the autonomous driving of the seedling transplanter 1 in the field. The driving control unit 104 has an autonomous driving mode in which the steering motor 95 (refer to Figure 3) is controlled to operate the steering wheel 35 (refer to Figure 3) while feeding back the steering amount of the front wheels 10 (refer to Figure 1). The autonomous driving mode includes an automatic straight-line driving mode and an automatic turning mode.

[0079] As shown in Figure 5, in autonomous driving mode, the seedling transplanter 1 automatically performs seedling transplanting operations in the field while repeatedly moving in a straight line and turning along a predetermined driving path. In addition, as described above, the driving control unit 104 obtains the current position information of the seedling transplanter 1 and information related to the turning position by means of the position acquisition device 150 disposed above the driving vehicle body 2.

[0080] The seedling transplanter 1 plants seedlings while reciprocating within a predetermined work area in the field. In this case, regarding straight-line travel, the travel control unit 104 executes an automatic straight-line travel mode, thereby automatically traveling along a set straight-line travel path L1. Furthermore, regarding turning travel, the travel control unit 104 executes an automatic turning mode, thereby automatically turning along a turning travel path L2.

[0081] The straight-line driving path L1 is parallel to the reference line L0, which serves as the driving reference. The reference line L0 is set in the field in the same direction as the planting direction of the rice seedlings. The driving control unit 104 obtains the start position and end position of the straight-line driving as the reference start point (point A) and reference end point (point B), respectively, and stores the line segment connecting point A and point B as the reference line L0.

[0082] During the turning process of the seedling transplanter 1, the driving control unit 104 controls the steering motor 95 in a manner that makes the steering amount of the steering wheel 35 a predetermined steering amount. In this case, the driving control unit 104 performs processing independently of the position information obtained by the position acquisition device 150. The predetermined steering amount is a preset value. The predetermined steering amount is set according to the type of seedling transplanter 1, etc. The predetermined steering amount is set to enable a smooth transition from automatic turning to automatic straight-line travel.

[0083] If the position of the seedling transplanter 1 after automatic turning deviates from the straight-line travel path L1 of the next automatic straight-line travel, the vehicle body 2 will sway more after the automatic turn when adjusting to align with the straight-line travel path L1. Furthermore, for example, the operator must operate the steering wheel 35 to align with the straight-line travel path L1 for the next automatic straight-line travel, increasing the operator's workload. Additionally, the driving posture of the seedling transplanter 1 may become distorted. In view of these aspects, the predetermined steering amount is set to allow for a smooth transition from automatic turning to automatic straight-line travel.

[0084] In addition, the driving control unit 104 can also control the steering motor 95 to reach any desired position on the set turning driving path L2 based on the position information obtained by the position acquisition device 150 during the turning process of the seedling transplanter 1. In addition, the controller 100 can also combine the two automatic turning modes mentioned above to perform automatic turning.

[0085] The driving control unit 104 controls the steering motor 95 in such a way that after turning by automatic turning, the seedling transplanter 1 reaches the automatic straight-line planting start position for the next project.

[0086] When performing autonomous driving, the driving control unit 104 controls the steering motor 95 based on the steering amount of the steering wheel 35 detected by the steering amount sensor 91. Specifically, the driving control unit 104 performs autonomous driving in a direction of travel along the reference line L0, i.e., the reference direction, based on the steering amount of the steering wheel 35 detected by the steering amount sensor 91.

[0087] Here, the case of switching to autonomous driving mode when the seedling transplanter 1 is in a straight-line driving path L1 will be explained. When the driving control unit 104 is in a straight-line driving path L1, it switches to autonomous driving mode (automatic straight-line driving mode) when the seedling transplanter 1 meets predetermined conditions.

[0088] Specifically, the driving control unit 104 switches from manual driving mode to autonomous driving mode when the following conditions (i) to (iv) are met: (i) Position information is detected normally by the position acquisition device (150); (ii) The body posture is less than a predetermined angle (e.g., 8 degrees); (iii) The auxiliary transmission is not in high-speed mode; (iv) The direction of travel is not the backward direction.

[0089] Furthermore, when the driving control unit 104 switches to autonomous driving mode when the direction of travel of the seedling transplanter 1 deviates from the reference direction, it switches to manual driving mode after a predetermined first time. This will be explained using Figure 6.

[0090] Figure 6 is a diagram showing the processing of the travel control unit 104. In Figure 6, it shows the case where the travel direction (solid arrow) of the seedling transplanter 1 deviates from the predetermined deviation angle α relative to the reference direction (the direction of the reference line L0).

[0091] As shown in Figure 6, when the travel control unit 104 switches to autonomous driving mode when the deviation angle α between the travel direction of the seedling transplanter 1 and the reference direction is greater than or equal to a predetermined angle, the autonomous driving mode is deactivated after a predetermined first time. Furthermore, the first time is set based on the deviation angle α. Specifically, the larger the deviation angle α, the shorter the first time is set; the smaller the deviation angle α, the longer the first time is set.

[0092] That is, the driving control unit 104 takes into account that the direction of travel of the seedling transplanter 1 is in the middle of returning to the reference direction and waits for the deviation angle α to return to a value less than a predetermined angle. More specifically, the smaller the deviation angle α, the higher the probability of returning to a value less than the predetermined angle, so the first time is extended; the larger the deviation angle α, the lower the probability of returning to a value less than the predetermined angle, so the first time is shortened.

[0093] Thus, for example, even when the direction of travel returns to the reference direction immediately after an automatic turn, or even if the autonomous driving mode is switched prematurely by mistake, a mode transfer that ensures a margin corresponding to the first moment can be performed.

[0094] Furthermore, in Figure 6, the mode transition is explained using an example of deviation angle α, but the same process can also be performed in the planting unit 4, which is the work machine. Specifically, when the travel control unit 104 transitions to autonomous travel mode when the planting unit 4 is at or above a predetermined height relative to the field, the autonomous travel mode is deactivated after a predetermined second time. The second time is set based on the height position. Specifically, the higher the height position (the further away from the predetermined height position), the shorter the second time is set; the lower the height position (the closer to the predetermined height position), the longer the second time is set. The predetermined height position corresponds to the height of the working position of the planting unit 4.

[0095] That is, the driving control unit 104 takes into account that the height position of the insertion unit 4 is in the process of recovering to a height lower than the predetermined height, and thus waits for the height position to recover to a height lower than the predetermined height. More specifically, the lower the height position, the higher the probability of recovering to a height lower than the predetermined height, so the second time is extended; the higher the height position, the lower the probability of recovering to a height lower than the predetermined height, so the second time is shortened.

[0096] Thus, for example, when the height position of the insertion section 4 returns to a height less than the predetermined height, even if the autonomous driving mode is switched prematurely by mistake, a mode transfer that ensures a margin corresponding to the second time can be performed.

[0097] Next, the processes performed by the controller 100 of the embodiment will be described using flowcharts in Figures 7 to 9. Figure 7 is a flowchart illustrating the processes performed during idling. Figures 8 and 9 are flowcharts illustrating the processes related to mode transition.

[0098] As shown in Figure 7, the controller 100 detects the rotational speed of the left and right front wheels 10 respectively (step S101).

[0099] Next, the controller 100 determines whether the front wheel 10 is in an idle state based on the left and right difference in rotation speed (step S102).

[0100] In the case of idling (step S102: Yes), the controller 100 operates the differential lock mechanism 97 of the front wheel 10 (step S103). Alternatively, if the controller 100 is not in the case of idling (step S102: No), it proceeds to step S101.

[0101] Next, the controller 100 detects the rotation of the rear wheel 11, which is the driven wheel (step S104).

[0102] The controller 100 determines whether the idling state has been eliminated based on the result of the rotation detection of the rear wheel 11 (step S105).

[0103] If the idling state is eliminated (step S105: Yes), the controller 100 ends the process; if the idling state is not eliminated (step S105: No), it returns to step S104.

[0104] Next, as shown in Figure 8, the controller 100 obtains the reference direction for the automatic straight-line movement of the seedling transplanter 1 (step S201).

[0105] Next, assume that the controller 100 meets the predetermined conditions and switches to autonomous driving mode (step S202).

[0106] Next, the controller 100 calculates the deviation angle α of the travel direction relative to the reference direction (step S203).

[0107] Next, the controller 100 determines whether the deviation angle α is above the predetermined angle (step S204).

[0108] When the deviation angle α is above a predetermined angle (step S204: Yes), the controller 100 determines whether to eliminate the deviation within a first time (step S205).

[0109] If the controller 100 eliminates the deviation within the first time (step S205: Yes), it continues the autonomous driving mode (step S206) and ends the process.

[0110] In addition, if the deviation angle α is less than the predetermined angle (step S204: No), the controller 100 continues the autonomous driving mode (step S206) and ends the process.

[0111] In addition, if the controller 100 fails to eliminate the deviation within the first time (step S205: No), the autonomous driving mode is deactivated (step S207), and the process ends.

[0112] Next, as shown in Figure 9, the controller 100 obtains the reference direction for the automatic straight-line movement of the seedling transplanter 1 (step S301).

[0113] Next, assume that the controller 100 meets the predetermined conditions and switches to autonomous driving mode (step S302).

[0114] Next, the controller 100 detects the height position of the insertion part 4, which is the work machine (step S303).

[0115] Next, the controller 100 determines whether the height position is above the predetermined height (step S304).

[0116] When the height position is above the predetermined height (step S304: Yes), the controller 100 determines whether the height position becomes below the predetermined height within a second time period (step S305).

[0117] If the controller 100 becomes lower than the predetermined height within the second time (step S305: Yes), continue the autonomous driving mode (step S306) and end the process.

[0118] In addition, if the controller 100 is in a position where the height is less than the predetermined height (step S304: No), it continues the autonomous driving mode (step S306) and ends the process.

[0119] In addition, if the controller 100 does not become lower than the predetermined height within the second time (step S305: No), the autonomous driving mode is deactivated (step S307), and the process ends.

[0120] As described above, the controller 100 of the embodiment includes a detection unit 101 and an idle detection unit 102. The detection unit 101 detects the rotational speed of each wheel of a work vehicle operating in the field in the left and right directions, and the wheels can be differentially controlled to rotate at different speeds to the left and right when turning. The idle detection unit 102 detects the idle state of the wheels based on the difference between the rotational speeds of the left and right wheels. In this way, the idle state can be detected at low cost.

[0121] Those skilled in the art can readily derive further effects and modifications. Therefore, the invention is not limited to the specific detailed and representative embodiments shown and described above. Thus, various modifications can be made without departing from the spirit or scope of the overall invention as defined by the appended claims and their equivalents. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a side view of the working vehicle. Figure 2 is a top view of the working vehicle. Figure 3 is a block diagram of the control system centered on the control device of the seedling transplanter. Figure 4 is a block diagram of the functional structure of the controller. Figure 5 is an illustration of the autonomous movement of the seedling transplanter in the field. Figure 6 is a diagram illustrating the processing of the driving control unit. Figure 7 is a flowchart illustrating the processing implemented during idling. Figure 8 is a flowchart illustrating the processing related to mode transfer. Figure 9 is a flowchart illustrating the processing related to mode transfer.

Claims

1. A control device, characterized in that: when a work vehicle operating in a field makes a turn for transferring to the next project, the ratio of the rotational speeds of the left and right wheels of the work vehicle is calculated, and if the ratio deviates from a predetermined value from a reference value, the wheel idling state is detected; the control device includes a position acquisition device, the position acquisition device acquires the current position and orientation of the work vehicle, and in the case of the wheel idling state, the idling state of the wheel is detected as having been eliminated based on whether the position acquired by the position acquisition device has changed.

2. The control device as claimed in claim 1, wherein, The control device further includes a drive control unit. When turning, it can perform differential control by rotating at different speeds to the left and right, and when the idling state is detected, the drive control unit activates the differential lock mechanism that locks the wheels. Even if the differential lock mechanism is activated and the idling state is not eliminated, the inner rear wheel, which is the driven wheel during turning, is switched from a driven wheel to a drive wheel. The control device further includes a remote operating unit for remotely operating the vehicle. Through the remote operating unit, the inner rear wheel, which is the driven wheel during turning, can be switched to a drive wheel regardless of the presence or absence of idling, ensuring the differential lock mechanism is always operational. Through the remote operating unit, the rear wheel can be switched from a drive wheel to a drive wheel, disengaging the differential lock mechanism.

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