JP7544778B2 - Autonomous driving system for work vehicles - Google Patents

Description

The present invention relates to an automatic driving system for a work vehicle equipped with an automatic driving control unit that automatically drives the work vehicle within a driving area based on positioning information acquired using a satellite positioning system.

Some work vehicles capable of autonomous driving are equipped with an obstacle sensor that detects the presence or absence of obstacles around the work vehicle, a sensitivity adjustment means that adjusts the detection distance of the obstacle sensor, and a control device that stops the work vehicle when the obstacle sensor detects the presence of an obstacle, thereby preventing the work vehicle from coming into contact with the obstacle. In addition, the control device calculates the distance from the current position of the work vehicle to the edge of the field in the direction of travel based on the set travel route set before work begins and the current position of the work vehicle obtained using a satellite positioning system, and shortens the detection distance of the obstacle sensor as the work vehicle approaches the edge of the field, thereby preventing the obstacle sensor from erroneously detecting objects outside the field as obstacles when the work vehicle approaches the edge of the field, thereby avoiding a decrease in work efficiency caused by the control device unnecessarily stopping the work vehicle based on the erroneous detection (see, for example, Patent Document 1).

International Publication No. WO 2015/147149

In the work vehicle described in Patent Document 1, in order to prevent the obstacle sensor from erroneously detecting an object outside the field as an obstacle, while the work vehicle is automatically traveling toward the field edge, the control device must continue to perform a calculation process to calculate the distance from the current position of the work vehicle to the field edge in the direction of travel, and a detection limiting process to shorten the detection distance of the obstacle sensor as the work vehicle approaches the field edge, which places a heavy load on the control device.

In addition, if the speed of the work vehicle within the travel area is set to a relatively high speed in order to improve the work efficiency of the work vehicle, the control device will obtain the current position of the work vehicle using a satellite positioning system, and then calculate the distance from the current position of the work vehicle to the edge of the field in the direction of travel based on this current position and the set travel route. At the point when the detection range of the obstacle sensor is changed to a shorter distance in accordance with this distance, the work vehicle will be approaching the edge of the field in the direction of travel. Therefore, even if the detection range of the obstacle sensor is shortened in accordance with the aforementioned distance, there is a risk that part of the detection range will be outside the field and other objects outside the field will be erroneously detected as obstacles.

When such a false detection occurs, the control device will perform unnecessary contact avoidance processing, such as stopping the work vehicle, for obstacles outside the field that the work vehicle is unlikely to come into contact with, resulting in reduced work efficiency when the work vehicle is operating autonomously.

In addition, to prevent erroneous detections such as those described above, it is possible to change the detection range of the obstacle sensor, which has been shortened according to the separation distance, to an appropriate short range according to the separation distance and vehicle speed by making a correction according to the work vehicle's speed. However, in this case, the load on the control device will become even heavier as the control device makes the above-mentioned correction.

In view of this situation, the main objective of the present invention is to reduce the load on the control device while avoiding the risk of falsely detecting objects outside the field as obstacles, thereby preventing a decrease in work efficiency due to false detection.

An automatic driving system for a work vehicle according to one aspect of the present invention includes an automatic driving control unit and a detection unit. The automatic driving control unit causes the work vehicle to automatically drive within a specified driving area. The detection unit detects the presence or absence of an object around the work vehicle. Furthermore, the detection unit determines whether the position of the detected object is within the driving area.

FIG. 1 is a diagram showing a schematic configuration of an automatic driving system for a work vehicle. A block diagram showing the schematic configuration of an automatic driving system for a work vehicle. FIG. 13 is a diagram showing an example of a target route generated by a target route generating unit; A diagram showing the measurement range of each lidar sensor in a side view A diagram showing the measurement range of each lidar sensor in a plan view A diagram showing the position (coordinates) of the measurement target in the vehicle body coordinate system. A diagram showing the position (coordinates) of the measurement target in the field coordinate system. A diagram showing obstacle determination for a measurement object in a rectangular travel area. FIG. 13 is a diagram showing obstacle determination for a measurement object in a U-shaped travel area. Flowchart of Obstacle Judgment Control FIG. 13 is a diagram showing an obstacle determination for a measurement object in another embodiment in which a reference position used for determining the position of the measurement object is set within a travel area; 4 is a flowchart of an obstacle determination control according to another embodiment. FIG. 13 is a diagram showing an obstacle determination for a measurement object in another embodiment in which a reference position used for determining the position of the measurement object is set outside the travel area;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as one example of a form for carrying out the present invention, an embodiment in which an automatic driving system for a work vehicle according to the present invention is applied to a tractor, which is one example of a work vehicle, will be described with reference to the drawings.
In addition, the automatic driving system for work vehicles according to the present invention can be applied to ride-on work vehicles other than tractors, such as riding lawn mowers, riding rice transplanters, combines, wheel loaders, snowplows, and unmanned work vehicles, such as unmanned lawn mowers.

As shown in FIG. 3, the tractor 1 illustrated in this embodiment is configured to be capable of automatic driving in a field A, which is an example of a work site, by an automatic driving system for work vehicles. As shown in FIGS. 1 and 2, the automatic driving system includes an automatic driving unit 2 mounted on the tractor 1, and a mobile communication terminal 3, which is an example of a wireless communication device set to be able to wirelessly communicate with the automatic driving unit 2. The mobile communication terminal 3 can be a tablet-type personal computer or a smartphone having a multi-touch display unit (e.g., a liquid crystal panel) 4 that allows various information display and input operations related to automatic driving.

As shown in Fig. 1, a rotary tilling device 6, which is an example of a working device, is connected to the rear of the tractor 1 so as to be capable of lifting, lowering and rolling via a three-point linkage mechanism 5. As a result, the tractor 1 is configured for rotary tilling.
In addition, instead of the rotary tilling device 6, various types of work implements such as a plow, a disc harrow, a cultivator, a subsoiler, a seed sowing device, a spreading device, and a grass cutting device can be connected to the rear of the tractor 1.

As shown in Figures 1 and 2, the tractor 1 is equipped with left and right front wheels 10 that can be driven and steered, left and right rear wheels 11 that can be driven, a cabin 13 that forms a riding driver's section 12, an electronically controlled diesel engine (hereinafter referred to as the engine) 14 having a common rail system, a transmission unit 15 that changes the speed of power from the engine 14, a fully hydraulic power steering unit 16 that steers the left and right front wheels 10, a brake unit 17 that brakes the left and right rear wheels 11, an electronically controlled work clutch unit 19 that interrupts the transmission to the rotary tilling device 6, an electronically controlled lifting drive unit 20 that drives the rotary tilling device 6 to lift and lower, an electronically controlled rolling drive unit 21 that drives the rotary tilling device 6 in the roll direction, a vehicle state detection device 23 including various sensors and switches that detect various setting states and operating states of each part in the tractor 1, a positioning unit 24 that measures the current position and current direction of the tractor 1, and an on-board control unit 40 having various control units.
An electronically controlled gasoline engine having an electronic governor may be used as the engine 14. The power steering unit 16 may be an electric type having an electric motor.

The driver's section 12 is equipped with a steering wheel 30 for manual steering (see FIG. 1), a seat 31 for the passenger, and a multi-touch LCD monitor 32 that allows various information displays and input operations, as well as control levers such as an accelerator lever and a gear lever, and control pedals such as an accelerator pedal and a clutch pedal.

Although not shown, the transmission unit 15 includes an electronically controlled continuously variable transmission that changes the speed of the power from the engine 14, and an electronically controlled forward/reverse switching device that switches the power after the speed change by the continuously variable transmission between forward and reverse. The continuously variable transmission employs an I-HMT (Integrated Hydro-static Mechanical Transmission), which is an example of a hydromechanical continuously variable transmission with higher transmission efficiency than a hydrostatic continuously variable transmission (HST: Hydro Static Transmission). The forward/reverse switching device includes a hydraulic clutch for interrupting forward power, a hydraulic clutch for interrupting reverse power, and an electromagnetic valve for controlling the flow of oil to them.
Note that, instead of the I-HMT, the continuously variable transmission may be an HMT (Hydraulic Mechanical Transmission), which is an example of a hydromechanical continuously variable transmission, a hydrostatic continuously variable transmission, or a belt type continuously variable transmission. Also, instead of the continuously variable transmission, the transmission unit 15 may include an electronically controlled stepped transmission having a plurality of hydraulic clutches for shifting and a plurality of electromagnetic valves for controlling the flow of oil to the clutches.

Although not shown in the figure, the brake unit 17 includes left and right brakes that brake the left and right rear wheels 11 separately, a foot brake system that activates the left and right brakes in conjunction with the depression of the left and right brake pedals provided on the driver's unit 12, a parking brake system that activates the left and right brakes in conjunction with the operation of a parking lever provided on the driver's unit 12, and a turning brake system that activates the brakes on the inside of a turn in conjunction with steering the left and right front wheels 10 beyond a set angle.

As shown in FIG. 2, the vehicle control unit 40 includes an engine control unit 41 that controls the engine 14, a vehicle speed control unit 42 that controls the tractor 1's speed and forward/reverse switching, a steering control unit 43 that controls steering, a work device control unit 44 that controls work devices such as the rotary tiller 6, a display control unit 45 that controls displays and notifications using the LCD monitor 32, an automatic driving control unit 46 that controls automatic driving, and a non-volatile vehicle memory unit 47 that stores target routes for automatic driving generated according to driving areas divided within the work site. Each of the control units 41 to 46 is constructed using an electronic control unit that integrates a microcontroller and various control programs. Each of the control units 41 to 46 is connected to each other so that they can communicate with each other via a CAN (Controller Area Network).

The vehicle state detection device 23 is a collective term for various sensors, switches, etc. provided in various parts of the tractor 1. The vehicle state detection device 23 includes an accelerator sensor that detects the operating position of the accelerator lever, a first position sensor for shifting that detects the operating position of the gear lever, a second position sensor for switching between forward and reverse that detects the operating position of the reverse lever for switching between forward and reverse, a rotation sensor that detects the output speed of the engine 14, a vehicle speed sensor that detects the vehicle speed of the tractor 1, and a steering angle sensor that detects the steering angle of the front wheels 10.

The engine control unit 41 performs engine speed maintenance control, which maintains the engine speed at a speed that corresponds to the operating position of the accelerator lever, based on detection information from the accelerator sensor and detection information from the rotation sensor.

The vehicle speed control unit 42 executes vehicle speed control that controls the operation of the continuously variable transmission so that the vehicle speed of the tractor 1 is changed to a speed corresponding to the operating position of the shift lever based on detection information from the first position sensor and detection information from the vehicle speed sensor, and forward/reverse switching control that switches the transmission state of the forward/reverse switching device based on detection information from the second position sensor. The vehicle speed control includes a deceleration/stop process that, when the shift lever is operated to the zero speed position, controls the continuously variable transmission to decelerate to the zero speed state to stop the tractor 1 from traveling.

The positioning unit 24 includes a satellite navigation device 25 that uses a GPS (Global Positioning System), which is an example of a navigation satellite system (NSS), to measure the current position and current direction of the tractor 1, and an inertial measurement unit (IMU) 26 that has a three-axis gyroscope and a three-directional acceleration sensor to measure the attitude and direction of the tractor 1. Positioning methods using GPS include DGPS (Differential GPS: relative positioning method) and RTK-GPS (Real Time Kinematic GPS: interferometric positioning method). In this embodiment, RTK-GPS, which is suitable for positioning a moving object, is used. For this reason, as shown in Figure 1, reference stations 73 that enable positioning using RTK-GPS are installed at known positions around the field.

As shown in Figures 1 and 2, the tractor 1 and the reference station 73 are each equipped with a GPS antenna 75, 76 for receiving radio waves transmitted from a GPS satellite 74 (see Figure 1), and communication modules 77, 78 for enabling wireless communication of information, including positioning information, between the tractor 1 and the reference station 73. This allows the satellite navigation device 25 of the positioning unit 24 to measure the current position and current orientation of the tractor 1 with high accuracy based on the positioning information obtained by the tractor's GPS antenna 75 receiving radio waves from the GPS satellite 74 and the positioning information obtained by the base station's GPS antenna 76 receiving radio waves from the GPS satellite 74. In addition, the positioning unit 24 has the satellite navigation device 25 and the inertial measurement unit 26, and can therefore measure the current position, current orientation, and attitude angles (yaw angle, roll angle, and pitch angle) of the tractor 1 with high accuracy.

In this tractor 1, the inertial measurement device 26, GPS antenna 75, and communication module 77 of the positioning unit 24 are included in an antenna unit 79 shown in FIG. 1. The antenna unit 79 is located in the center of the upper left and right part of the front side of the cabin 13. The mounting position of the GPS antenna 75 on the tractor 1 is the positioning target position p0 when measuring the current position of the tractor 1 using GPS (see FIG. 3).

2, the mobile communication terminal 3 includes a terminal control unit 80 having an electronic control unit with an integrated microcontroller and various control programs, and a communication module 90 that enables wireless communication of information including positioning information with the communication module 77 on the tractor side. The terminal control unit 80 includes a display control unit 81 that controls the operation of the display unit 4, a target route generation unit 82 that generates a target route P for automatic driving, and a non-volatile terminal storage unit 83 that stores the target route P generated by the target route generation unit 82. The terminal storage unit 83 stores various information used to generate the target route P, such as vehicle information such as the turning radius and working width of the tractor 1, and field information obtained from the above-mentioned positioning information. As shown in FIG. 3, the field information includes four corner points Ap1 to Ap4, which are multiple shape-specific points (shape-specific coordinates) in field A acquired using GPS when tractor 1 is driven along the outer edge of field A to identify the shape, size, etc. of field A, and a rectangular shape-specific line AL that connects these corner points Ap1 to Ap4 to identify the shape, size, etc. of field A.

As shown in FIG. 3, the target route generating unit 82 generates a target route P based on the turning radius and working width of the tractor 1 contained in the vehicle information, and the shape and size of the field A contained in the field information.
Specifically, as shown in Figure 3, for example, in a rectangular field A, when a start point p1 and an end point p2 of automatic driving are set and the work driving direction of the tractor 1 is set to be along the short side of the field A, the target route generating unit 82 first divides the field A into a margin area A1 adjacent to the outer periphery of the field A and a driving area A2 located inside the margin area A1 based on the four corner points Ap1 to Ap4 and the rectangular shape specific line AL described above.
In other words, in the rectangular field A shown in Figure 3, the four corner points Ap1 to Ap4 also serve as area identification points used to identify the driving area A2, and the rectangular shape identification line AL also serves as an area identification line that identifies the driving area A2.
Next, based on the turning radius and working width of the tractor 1, the target path generation unit 82 generates a plurality of parallel paths P1 in the traveling area A2 that are arranged in parallel at regular intervals according to the working width in a direction along the long side of the field A, and also generates a plurality of turning paths P2 that are arranged on the outer edges of each long side of the traveling area A2 and connect the multiple parallel paths P1 in traveling order.
The traveling area A2 is then divided into a pair of non-working areas A2a set on the outer edges of each long side of the traveling area A2, and a working area A2b set between the pair of non-working areas A2a, and each parallel path P1 is divided into a non-working path P1a included in the pair of non-working areas A2a, and a working path P1b included in the working area A2b.
This enables the target route generating unit 82 to generate a target route P suitable for automatically traveling the tractor 1 in the field A shown in Figure 3.

In the field A shown in FIG. 3, the margin area A1 is an area secured between the outer edge of the field A and the travel area A2 to prevent the rotary tillage device 6 and other devices from contacting other objects such as ridges adjacent to the field A when the tractor 1 automatically travels on the outer periphery of the travel area A2. Each non-working area A2a is a ridge-edge turning area for the tractor 1 to turn from the current working path P1b to the next working path P1b at the ridge edge of the field A.

In the target path P shown in FIG. 3, each non-work path P1a and each turning path P2 is a path along which the tractor 1 automatically travels without performing tilling work, and each of the above-mentioned working paths P1b is a path along which the tractor 1 automatically travels while performing tilling work. The starting point p3 of each working path P1b is the work start point where the tractor 1 starts tilling work, and the ending point p4 of each working path P1b is the work stop point where the tractor 1 stops tilling work. Each non-work path P1a is an alignment path for aligning the work stop point p4 before the tractor 1 turns on the turning path P2 and the work start point p3 after the tractor 1 turns on the turning path P2 in the work travel direction of the tractor 1. Of the connection points p5 and p6 between each parallel path P1 and each turning path P2, the connection point p5 at the end of each parallel path P1 is the turning start point of the tractor 1, and the connection point p6 at the beginning of each parallel path P1 is the turning end point of the tractor 1.

The target route P shown in FIG. 3 is merely an example, and the target route generating unit 82 can generate various target routes P suitable for the various conditions based on vehicle body information that differs depending on the model of tractor 1 and the type of work, and field information such as the shape and size of field A that differs depending on field A.

The target route P is stored in the terminal storage unit 83 in association with vehicle information, field information, etc., and can be displayed on the display unit 4 of the mobile communication terminal 3. The target route P includes the target vehicle speed of the tractor 1 on each parallel route P3, the target vehicle speed of the tractor 1 on each turning route P2b, the front wheel steering angle on each parallel route P1, and the front wheel steering angle on each turning route P2b.

In response to a transmission request command from the vehicle control unit 40, the terminal control unit 80 transmits the vehicle body information, field information, target route P, and the like stored in the terminal storage unit 83 to the vehicle control unit 40. The vehicle control unit 40 stores the received vehicle body information, field information, target route P, and the like in the vehicle storage unit 47. Regarding the transmission of the target route P, for example, the terminal control unit 80 may transmit all of the target route P from the terminal storage unit 83 to the vehicle control unit 40 at once before the tractor 1 starts automatic traveling. Also, for example, the terminal control unit 80 may divide the target route P into a plurality of divided route information for each predetermined distance, and sequentially transmit a predetermined number of divided route information according to the traveling order of the tractor 1 from the terminal storage unit 83 to the vehicle control unit 40 each time the traveling distance of the tractor 1 reaches a predetermined distance from the stage before the tractor 1 starts automatic traveling.

In the on-board control unit 40, detection information from various sensors and switches included in the vehicle state detection device 23 is input to the automatic driving control unit 46 via the vehicle speed control unit 42, steering control unit 43, etc. This allows the automatic driving control unit 46 to monitor various settings and the operating state of each unit in the tractor 1.

When the driving mode of the tractor 1 is switched to the automatic driving mode and a user such as a passenger or an administrator outside the vehicle operates the display unit 4 of the mobile communication terminal 3 to command the start of automatic driving, the automatic driving control unit 46 starts automatic driving control to automatically drive the tractor 1 according to the target route P while acquiring the current position and current direction of the tractor 1 using the positioning unit 24.

The automatic driving control by the automatic driving control unit 46 includes an automatic engine control process that transmits automatic driving control commands related to the engine 14 to the engine control unit 41, an automatic vehicle speed control process that transmits automatic driving control commands related to the vehicle speed of the tractor 1 and switching between forward and reverse travel to the vehicle speed control unit 42, an automatic steering control process that transmits automatic driving control commands related to the steering to the steering control unit 43, and an automatic work control process that transmits automatic driving control commands related to work implements such as the rotary tilling implement 6 to the work implement control unit 44.

In the automatic engine control process, the automatic driving control unit 46 transmits to the engine control unit 41 an engine speed change command that instructs a change in engine speed based on the set speed included in the target route P. The engine control unit 41 executes engine speed change control that automatically changes the engine speed in response to various control commands related to the engine 14 transmitted from the automatic driving control unit 46.

In the automatic vehicle speed control process, the automatic travel control unit 46 transmits to the vehicle speed control unit 42 a speed change operation command that instructs the speed change operation of the continuously variable transmission based on the target vehicle speed included in the target route P, and a forward/reverse switch command that instructs the forward/reverse switch operation of the forward/reverse switch based on the traveling direction of the tractor 1 included in the target route P. The vehicle speed control unit 42 executes an automobile speed control that automatically controls the operation of the continuously variable transmission, and an automatic forward/reverse switch control that automatically controls the operation of the forward/reverse switch in response to various control commands related to the continuously variable transmission and the forward/reverse switch transmitted from the automatic travel control unit 46. The automobile speed control includes, for example, an automatic deceleration/stop process that decelerates the continuously variable transmission to a zero-speed state to stop the travel of the tractor 1 when the target vehicle speed included in the target route P is zero.

In the automatic control process for steering, the automatic driving control unit 46 transmits to the steering control unit 43 steering commands instructing the steering of the left and right front wheels 10 based on the front wheel steering angle included in the target route P. In response to the steering commands transmitted from the automatic driving control unit 46, the steering control unit 43 executes automatic steering control for controlling the operation of the power steering unit 16 to steer the left and right front wheels 10, and automatic brake turning control for operating the brake unit 17 to apply the brakes on the inside of the turn when the left and right front wheels 10 are steered beyond a set angle.

In the automatic control process for work, the automatic travel control unit 46 transmits to the work device control unit 44 a work start command that instructs the rotary tilling device 6 to switch to a working state based on a work start point p3 included in the target route P, and a work stop command that instructs the rotary tilling device 6 to switch to a non-working state based on a work stop point p4 included in the target route P. In response to various control commands related to the rotary tilling device 6 transmitted from the automatic travel control unit 46, the work device control unit 44 controls the operation of the lifting drive unit 20 and the work clutch unit 19 to execute automatic work start control that lowers the rotary tilling device 6 to the working height and operates it, and automatic work stop control that stops the rotary tilling device 6 and raises it to the non-working height. In addition, when the rotary tilling device 6 is lowered to the working height and is in operation, the working device control unit 44 performs automatic tilling depth maintenance control, which controls the operation of the lifting drive unit 20 to maintain the tilling depth of the rotary tilling device 6 at a set depth based on the detection of the tilling depth sensor that detects the tilling depth of the rotary tilling device 6, and automatic roll angle maintenance control, which controls the operation of the rolling drive unit 21 to maintain the tilt position of the rotary tilling device 6 in the roll direction at a set position (e.g., horizontal position) based on the detection of the tilt sensor that detects the roll angle of the tractor 1 and the acceleration sensor of the inertial measurement device 26.

In other words, the aforementioned automatic driving unit 2 includes a power steering unit 16, a brake unit 17, a working clutch unit 19, a lifting drive unit 20, a rolling drive unit 21, a vehicle condition detection device 23, a positioning unit 24, an on-board control unit 40, and a communication module 77. By properly operating these, the tractor 1 can be automatically driven with high precision along the target route P, and the rotary tilling device 6 can be used to properly till the ground.

As shown in FIG. 2, the tractor 1 is equipped with an obstacle detection unit 50 that detects the presence or absence of obstacles 200 (see FIGS. 8-9) in its surroundings. The obstacles 200 detected by the obstacle detection unit 50 include people such as workers working within the travel area A2 of the field A, other work vehicles, and objects such as utility poles and trees that exist within the travel area A2 of the field A.

When the obstacle detection unit 50 detects the presence of the obstacle 200, the automatic driving control unit 46 performs a contact avoidance process to avoid the tractor 1 coming into contact with the obstacle 200. The contact avoidance process includes a notification process to activate a notification device provided on the tractor 1 and the mobile communication terminal 3, an automatic deceleration process to automatically reduce the vehicle speed of the tractor 1, an automatic deceleration stop process to reduce the vehicle speed of the tractor 1 to zero speed and stop the tractor 1, and an automatic steering process to automatically steer the left and right front wheels 10 to make the tractor 1 detour so as to avoid the obstacle 200. Each of these processes is configured to be appropriately performed by the automatic driving control unit 46 depending on the vehicle speed of the tractor 1, the distance from the tractor 1 to the obstacle 200, and the positional relationship between the tractor 1 and the obstacle 200.

As shown in Figures 1-2 and 4-5, the obstacle detection unit 50 has two front and rear LiDAR sensors (Light Detection and Ranging Sensors) 101, 102, which are an example of a relative position measurement unit that measures the relative position of a measurement object 201 (see Figures 6-9) located in front of and behind the tractor 1, and two sets of sonar units 103, 104 on the left and right that measure the distance from the tractor 1 to the measurement object 201 located on the left and right of the tractor 1.

As shown in Figures 4 and 5, each of the lidar sensors 101 and 102 uses a laser to measure the distance to the measurement object 201 in three dimensions and generate a three-dimensional image. Each of the lidar sensors 101 and 102 measures the distance to the measurement object 201 by a TOF (Time Of Flight) method that measures the distance to the measurement object 201 from the round-trip time it takes for a laser beam (e.g., a pulsed near-infrared laser beam) to hit the measurement object 201 and bounce back. Each of the lidar sensors 101 and 102 scans the laser beam in the vertical and horizontal directions at high speed and measures the distance to the measurement object 201 at each scanning angle in sequence, thereby measuring the distance to the measurement object 201 in three dimensions. Each of the lidar sensors 101 and 102 repeatedly measures the distance to the measurement object 201 within their measurement ranges C and D in real time. Each LIDAR sensor 101, 102 obtains the relative position of the measurement object 201 from the linear distance to the measurement object 201 and the irradiation angle relative to the measurement object 201 contained in each measurement result, and generates a three-dimensional image and outputs it to the on-board control unit 40. The three-dimensional images from each LIDAR sensor 101, 102 can be displayed on the liquid crystal monitor 32 of the tractor 1 or the display unit 4 of the mobile communication terminal 3, allowing the user to visually recognize the situation in front of and behind the tractor 1. Incidentally, in the three-dimensional image, the distance in the near and far directions can be indicated using, for example, color.

As shown in Figures 1, 4 and 5, of the front and rear lidar sensors 101, 102, the front lidar sensor 101 is disposed in a front-down position looking diagonally down at the front side of the tractor 1 from above, at the center of the left and right upper part of the front side of the cabin 13 where the antenna unit 79 is disposed. As a result, the front lidar sensor 101 is set so that the front side of the tractor 1 is the measurement range C. The rear lidar sensor 102 is disposed in a rear-down position looking diagonally down at the rear side of the tractor 1 from above, at the center of the left and right upper part of the rear end side of the cabin 13. As a result, the rear lidar sensor 102 is set so that the measurement range D is the rear side of the tractor 1.

In the measurement ranges C and D of each LIDAR sensor 101, 102, areas where a part of the tractor 1 or a part of the rotary tillage device 6 enters are masked to cover those areas so that each LIDAR sensor 101, 102 does not treat the part of the tractor 1 or the part of the rotary tillage device 6 that has entered those areas as the measurement target 201.

In addition, a cut process may be applied to the measurement ranges C and D of the lidar sensors 101 and 102 to limit their left-right range to a set range according to the working width of the rotary tilling device 6.

When the tractor 1 is traveling forward with the forward/reverse switching device of the transmission unit 15 switched to the forward transmission state, the front lidar sensor 101 is in a measurement state and the rear lidar sensor 102 is in a measurement stop state. When the tractor 1 is traveling backward with the forward/reverse switching device of the transmission unit 15 switched to the reverse transmission state, the front lidar sensor 101 is in a measurement stop state and the rear lidar sensor 102 is in a measurement state. When there are multiple measurement objects 201 within their measurement ranges C, D, the front and rear lidar sensors 101, 102 individually measure the distance to each measurement object 201, etc.

As shown in Figures 1, 4 and 5, each sonar unit 103, 104 uses ultrasonic waves to measure the distance to the measurement object 201. Each sonar unit 103, 104 measures the distance to the measurement object 201 by the TOF (Time Of Flight) method, which measures the distance to the measurement object 201 from the round trip time it takes for the emitted ultrasonic waves to hit the measurement object 201 and bounce back. Of the left and right sonar units 103, 104, the right sonar unit 103 is attached to the right boarding and disembarking step 13A located on the lower right side of the cabin 13 in a right downward orientation with a small depression angle. As a result, the right sonar unit 103 is located at a relatively high position between the right front wheel 10 and the right rear wheel 11 with the right outer side of the tractor 1 set to be the measurement range N. The left sonar unit 104 is attached to the left boarding/alighting step 13A located on the lower left side of the cabin 13 in a left-downward position with a small depression angle. As a result, the left sonar unit 104 is positioned at a relatively high position between the left front wheel 10 and the left rear wheel 11 with the left outer side of the tractor 1 set to be the measurement range N.

As shown in FIG. 2, the obstacle detection unit 50 has an obstacle determination section 48 that determines whether the measurement object 201 measured by the front and rear lidar sensors 101, 102 is an obstacle 200 or not. The obstacle determination section 48 is included in the vehicle control unit 40, and is constructed by an electronic control unit that integrates a microcontroller and various control programs. The vehicle control unit 40 is connected to each of the lidar sensors 101, 102 and each of the sonar units 103, 104 via CAN so that they can communicate with each other.

The obstacle determination unit 48 executes obstacle determination control to determine whether the measurement object 201 measured by the front and rear LIDAR sensors 101, 102 is an obstacle 200 or not, based on position information from the front and rear LIDAR sensors 101, 102. When executing the obstacle determination control, the obstacle determination unit 48 registers the mounting position of the GPS antenna 75, which is the GPS positioning target position p0 on the tractor 1, as the reference position used to determine the position of the measurement object 201.

Hereinafter, a processing procedure of the obstacle determining unit 48 in the obstacle determination control will be described with reference to the flowchart shown in FIG.
Note that only the LIDAR sensors 101, 102 that are in the measurement state are different when the tractor 1 is traveling forward and when it is traveling backward, and the processing procedure of the obstacle determination unit 48 in the obstacle determination control is the same. Therefore, here, as shown in Figures 6 to 8, an example will be described of the tractor 1 traveling forward, in which the front LIDAR sensor 101 is in the measurement state and the rear LIDAR sensor 102 is in the measurement stopped state.

In the obstacle determination control, the obstacle determination unit 48 first performs an object position determination process to determine the position of the measurement object 201 relative to the travel area A2 based on the position information from the front LIDAR sensor 101 and the like (step #1). In the object position determination process, the coordinates (x, y) of the measurement object 201 in the vehicle body coordinate system with the GPS positioning target position p0 of the tractor 1 as the origin (0, 0) are obtained from the relative position of the measurement object 201 measured by the front LIDAR sensor 101 and the mounting position of the GPS antenna 75 on the tractor 1 included in the vehicle body information (see FIG. 6). Then, the coordinates (x, y) of the measurement object 201 in the vehicle body coordinate system are converted into the field coordinate system (NED coordinate system) that determines the coordinates of each area determination point Ap1 to Ap4 and the like, and the coordinates (X, Y) of the measurement object 201 in the field coordinate system are determined (see FIG. 7).
Next, as shown in Figure 8, a judgment reference line generation process is performed to generate a judgment reference line L that spans the reference position (GPS positioning target position p0 in the tractor 1) registered in the obstacle determination unit 48 and the position of the identified measurement object 201 (step #2).
Then, an intersection determination process is performed to determine whether or not there is an intersection between the rectangular area identification line AL connecting each area identification point Ap1 to Ap4 and the aforementioned judgment reference line L (step #3), and then an obstacle determination process is performed to exclude from the obstacle 200 the measurement object 201 that is determined to have an intersection in this intersection determination process (step #4).

As a result, for example, as shown in FIG. 8, if the position of the measurement object 201 identified by the object position identification process is a first specific position sp1 relative to the area identification line AL, the obstacle determination unit 48 determines that the measurement object 201 is an obstacle 200 located within the travel area A2 since there is no intersection between the area identification line AL and the judgment reference line L. Also, if the position of the measurement object 201 identified by the object position identification process is a second specific position sp2 relative to the area identification line AL, there is an intersection between the area identification line AL and the judgment reference line L, so the obstacle determination unit 48 determines that the measurement object 201 is located outside the travel area A2 and excludes the measurement object 201 from the obstacle 200.

In addition, for example, as shown in Figure 9, when the shape of the driving area A2 is U-shaped in which a part outside the driving area A2 (hereinafter referred to as the non-driving part) extends toward the center of the driving area A2, if the identified position of the measured object 201 by the object position identification process is the first identified position sp1 relative to the area identification line AL, the obstacle determination unit 48 determines that the measured object 201 is an obstacle 200 located within the same partial area A2c as the partial area A2c in which the tractor 1 is automatically traveling, since there is no intersection between the area identification line AL and the judgment reference line L. Furthermore, if the identified position of the measured object 201 by the object position identification process is the second identified position sp2 or the third identified position sp3 relative to the area identification line AL, since there is an intersection between the area identification line AL and the judgment reference line L, it is determined that the measured object 201 is located outside the driving area A2, or in a partial area A2d different from the partial area A2c in which the tractor 1 is automatically traveling, and the measured object 201 is excluded from the obstacle 200.
Incidentally, the shape, size, etc. of the U-shaped travel area A2 shown in FIG. 9 are specified by an area specification line AL connecting eight area specification points Ap1 to Ap8.

In other words, by performing the object position identification process, the judgment reference line generation process, the intersection judgment process, and the obstacle judgment process described above, the obstacle judgment unit 48 can not only exclude the measurement object 201 located outside the traveling area A2 from the obstacle 200, but also, for example, when the shape of the traveling area A2 is a complex shape such as the U-shape described above, can exclude the measurement object 201 located in the partial area A2d different from the partial area A2c in which the tractor 1 is automatically traveling from the obstacle 200.

As a result, regardless of the shape of the travel area A2, when the tractor 1 is traveling automatically in the travel area A2, the obstacle detection unit 50 can be prevented from erroneously detecting, as an obstacle 200, a measurement object 201 located outside the travel area A2 or a measurement object 201 located in a partial area A2d different from the partial area A2c in which the tractor 1 is traveling automatically. This can prevent a decrease in work efficiency caused by the automatic traveling control unit 46 performing unnecessary contact avoidance processing due to such erroneous detection.

When the front or rear lidar sensor 101, 102 measures multiple measurement objects 201 and the obstacle determination unit 48 determines that the multiple measurement objects 201 are obstacles 200, the automatic driving control unit 46 performs contact avoidance processing based on the obstacle 200 that is closest to the tractor 1. This makes it possible to more effectively avoid the risk of the tractor 1 coming into contact with the obstacle 200.

As shown in Figures 1-2 and 4, the tractor 1 is equipped with two front and rear cameras 108, 109 whose imaging ranges cover the front and rear sides of the tractor 1. The front camera 108, like the front lidar sensor 101, is located in the center of the left and right upper part of the front side of the cabin 13, with a forward-downward posture overlooking the front side of the tractor 1 from diagonally above. The rear camera 109, like the rear lidar sensor 102, is located in the center of the left and right upper part of the rear end side of the cabin 13, with a rear-downward posture overlooking the rear side of the tractor 1 from diagonally above. Images captured by the cameras 108, 109 can be displayed on the liquid crystal monitor 32 of the tractor 1 or the display unit 4 of the mobile communication terminal 3, allowing the user to visually confirm the situation around the tractor 1.

[Another embodiment]
Another embodiment of the present invention will now be described.
The configurations of the respective alternative embodiments described below are not limited to being applied alone, but may also be applied in combination with the configurations of other alternative embodiments.

(1) Representative alternative embodiments relating to the configuration of the work vehicle 1 are as follows.
For example, the work vehicle 1 may be configured as a semi-crawler type having left and right crawlers instead of the left and right rear wheels 11 .
For example, the work vehicle 1 may be configured as a full crawler vehicle having left and right crawlers instead of the left and right front wheels 10 and the left and right rear wheels 11 .
For example, the work vehicle 1 may be configured to be electrically powered and equipped with an electric motor instead of the engine 14 .
For example, the work vehicle 1 may be configured as a hybrid vehicle equipped with an engine 14 and an electric motor.

(2) For example, the relative position measuring unit may be configured to use two pairs of sonar units 103, 104 on the left and right that measure the distance from the work vehicle 1 to the measurement object 201 located on the left and right, and the obstacle determining unit 48 may be configured to determine whether the position of the measurement object 201 is within the traveling area A2 or not based on the distance measurement information from the two pairs of sonar units 103, 104 on the left and right and the positioning information obtained using a satellite positioning system, and to exclude the measurement object 201 located outside the traveling area A2 from the obstacles 200.

(3) For example, a stereo camera may be used as the relative position measurement units 101 to 104.

(4) As shown in FIG. 11, a reference position p0i set within the travel area A2 for use in determining the position of the measurement object 201 is registered in the obstacle determination unit 48. In the obstacle determination control, as shown in the flowchart of FIG. 12, the obstacle determination unit 48 performs an object position identification process (step #1) for identifying the position of the measurement object 201 based on position information from the relative position measurement units (front and rear LIDAR sensors) 101, 102 and positioning information acquired using a satellite positioning system, and The system may be configured to perform a judgment reference line generation process (step #2) that generates a judgment reference line L extending to the reference position p0i, a number of intersections calculation process (step #3) that calculates the number of intersections between the area specification line AL and the judgment reference line L, an inside/outside determination process (step #4) that determines whether the position of the measured object 201 is within the driving area A2 based on the number of intersections obtained in the number of intersections calculation process, and an obstacle determination process (step #5) that excludes the measured object 201 that is determined to be outside the driving area A2 in the inside/outside determination process from the obstacle 200.
11, for example, if the position of the measurement object 201 identified by the object position identification process is a first specific position sp1 relative to the area identification line AL, the number of intersections between the area identification line AL and the judgment reference line L will be zero, and the obstacle determination unit 48 will determine that the measurement object 201 is an obstacle 200 located within the travel area A2. If the position of the measurement object 201 identified by the object position identification process is a second specific position sp2 relative to the area identification line AL, the number of intersections between the area identification line AL and the judgment reference line L will be an odd number, and the obstacle determination unit 48 will determine that the measurement object 201 is located outside the travel area A2, and will exclude the measurement object 201 from the obstacles 200.
9, the obstacle determination unit 48 determines that the measurement object 201 having the number of intersections between the area identification line AL and the judgment reference line L which is zero or an even number is an obstacle 200 located within the travel area A2. Also, the obstacle determination unit 48 determines that the measurement object 201 having the number of intersections between the area identification line AL and the judgment reference line L which is an odd number is located outside the travel area A2, and excludes the measurement object 201 from the obstacle 200.

(5) As shown in FIG. 13 , the obstacle determination unit 48 may be configured to register a reference position p0o set outside the traveling area A2 for use in determining the position of the object to be measured 201, and in the obstacle determination control, the obstacle determination unit 48 may be configured to perform an object position identification process for identifying the position of the object to be measured 201 based on position information from the relative position measurement units (front and rear LIDAR sensors) 101, 102 and positioning information acquired using a satellite positioning system, a determination reference line generation process for generating a determination reference line L extending between the identified position of the object to be measured 201 and the reference position p0o, an intersection number calculation process for calculating the number of intersections between the area identification line AL and the determination reference line L, an inside/outside determination process for determining whether the position of the object to be measured 201 is within the traveling area A2 based on the number of intersections obtained in the intersection number calculation process, and an obstacle determination process for excluding the object to be measured 201 determined to be outside the traveling area A2 in the inside/outside determination process from the obstacle 200.
13, for example, if the position of the measurement object 201 identified by the object position identification process is a first identified position sp1 with respect to the area identification line AL, the number of intersections between the area identification line AL and the judgment reference line L will be zero, so the obstacle determination unit 48 determines that the measurement object 201 is located outside the traveling area A2 and excludes the measurement object 201 from the obstacle 200. If the position of the measurement object 201 identified by the object position identification process is a second identified position sp2 with respect to the area identification line AL, the number of intersections between the area identification line AL and the judgment reference line L will be an odd number, so the obstacle determination unit 48 determines that the measurement object 201 is an obstacle 200 located within the traveling area A2.
9, the obstacle determination unit 48 determines that the measurement object 201 having the number of intersections between the area identification line AL and the judgment reference line L that is zero or an even number is located outside the travel area A2, and excludes the measurement object 201 from the obstacle 200. Moreover, the obstacle determination unit 48 determines that the measurement object 201 having the number of intersections between the area identification line AL and the judgment reference line L that is an odd number is located as the obstacle 200 located inside the travel area A2.

<Notes on the invention>
A first characteristic configuration of the present invention is an automatic driving system for a work vehicle,
A storage unit that stores area identification information used to identify a traveling area;
an automatic driving control unit that automatically drives a work vehicle within a specified driving area based on positioning information acquired using a satellite positioning system;
an obstacle detection unit that detects the presence or absence of an obstacle around the work vehicle;
the automatic travel control unit performs a contact avoidance process to avoid contact of the work vehicle with the obstacle when the obstacle detection unit detects the presence of the obstacle,
The obstacle detection unit has a relative position measuring unit provided on the work vehicle that measures the relative position of a measurement object, and an obstacle determination unit that determines whether the position of the measurement object is within the traveling area based on the position information from the relative position measuring unit, the positioning information, and the area identification information, and excludes the measurement object located outside the traveling area from the obstacles.

According to this configuration, the obstacle determination unit determines whether the position of the measurement object measured by the relative position measurement unit is within the travel area based on the current position of the work vehicle contained in the positioning information acquired using the satellite positioning system, the relative position of the measurement object measured by the relative position measurement unit, etc., and excludes measurement objects located outside the travel area from obstacles, thereby avoiding the risk of the obstacle detection unit erroneously detecting measurement objects located outside the travel area as obstacles.

This makes it possible to prevent a decrease in work efficiency caused by the automatic driving control unit performing contact avoidance processing based on a measured object outside the driving area that is erroneously detected as an obstacle when the work vehicle is driving automatically within the driving area.

In addition, while the work vehicle is automatically traveling toward the edge of the field, the obstacle detection unit does not need to continue to perform calculations to calculate the distance from the current position of the work vehicle to the edge of the field in the direction of travel, or distance measurement limiting processes to limit the measurement distance of the relative position measurement unit as the work vehicle approaches the edge of the field, thereby reducing the load on the obstacle detection unit.

As a result, it is possible to reduce the load on the obstacle detection unit while avoiding the risk of the obstacle detection unit mistakenly detecting an object outside the driving area as an obstacle, thereby preventing a decrease in work efficiency that would result from such a mistaken detection.

The second characteristic configuration of the present invention is as follows:
The area identification information includes a plurality of area identification points including corner points and inflection points of the work area where the travel area is identified, and an area identification line that connects the plurality of area identification points to identify the travel area,
a position to be measured by the satellite positioning system in the work vehicle is registered in the obstacle determination unit as a reference position to be used in determining the position of the object to be measured,
The obstacle determination unit performs an object position identification process to identify the position of the object to be measured based on the position information from the relative position measurement unit and the positioning information, a judgment reference line generation process to generate a judgment reference line extending between the identified position of the object to be measured and the reference position, an intersection determination process to determine whether or not there is an intersection between the area identification line and the judgment reference line, and an obstacle determination process to exclude the object to be measured that is determined to have an intersection in the intersection determination process from the obstacles.

According to this configuration, the obstacle determination unit can not only exclude measurement objects located outside the travel area from obstacles by performing the object position identification process, determination reference line generation process, intersection determination process, and obstacle determination process described above, but also, for example, when the shape of the travel area is U-shaped with a part outside the travel area (hereinafter referred to as the non-travel area) extending toward the center of the travel area, even if the relative position measurement unit measures a measurement object located in the partial area on the opposite side of the non-travel area when the work vehicle is automatically traveling toward the non-travel area in one of the adjacent partial areas across the non-travel area, this measurement object, i.e., the measurement object located in the partial area different from the partial area in which the work vehicle is automatically traveling, can be excluded from obstacles.

This makes it possible to avoid the risk of the obstacle detection unit erroneously detecting, as an obstacle, a measurement object located outside the driving area or a measurement object located in a partial area different from the partial area in which the work vehicle is driving automatically when the work vehicle is driving automatically within the driving area such as the U-shape described above, and to prevent a decrease in work efficiency due to such erroneous detection.

The third characteristic configuration of the present invention is as follows:
The area identification information includes a plurality of area identification points including corner points and inflection points of the work area where the travel area is identified, and an area identification line that connects the plurality of area identification points to identify the travel area,
The obstacle determination unit is configured to register a reference position set within or outside the traveling area for use in determining the position of the measurement object,
The obstacle determination unit performs an object position identification process that identifies the position of the object to be measured based on position information from the relative position measurement unit and the positioning information, a determination reference line generation process that generates a determination reference line that spans the identified position of the object to be measured and the reference position, an intersection number calculation process that calculates the number of intersections between the area identification line and the determination reference line, an inside/outside determination process that determines whether the position of the object to be measured is within the traveling area based on the number of intersections obtained in the intersection number calculation process, and an obstacle determination process that excludes the object to be measured that is determined to be outside the traveling area in the inside/outside determination process from the obstacles.

According to this configuration, the obstacle determination unit performs the object position identification process, determination reference line generation process, intersection number calculation process, inside/outside determination process, and obstacle determination process described above, and can easily determine whether the position of the measurement object measured by the relative position measurement unit is outside the driving area, not only when the shape of the driving area is a simple rectangle, but also when the shape is a complex shape such as the U-shape described above, and can exclude measurement objects located outside the driving area from obstacles.

Specifically, when the reference position registered in the obstacle determination unit is set within the driving area, a measurement object whose number of intersections is zero or an even number is determined to be located within the driving area and is determined to be an obstacle, and a measurement object whose number of intersections is an odd number is determined to be located outside the driving area and is excluded from the obstacles.
In addition, if the reference position registered in the obstacle determination unit is set outside the traveling area, a measurement object whose number of intersections is zero or an even number is determined to be located outside the traveling area and is excluded from the obstacles, and a measurement object whose number of intersections is an odd number is determined to be located within the traveling area and is determined to be an obstacle.

In other words, regardless of whether the shape of the travel area is a simple shape such as a rectangle or a complex shape such as the U-shape mentioned above, the obstacle determination unit can easily and reliably exclude measurement objects located outside the travel area from obstacles.

As a result, regardless of the shape of the driving area, when the work vehicle is traveling automatically within the driving area, the obstacle detection unit can be prevented from erroneously detecting a measurement object located outside the driving area as an obstacle, preventing a decrease in work efficiency due to such erroneous detection.

1 Work vehicle 46 Automatic driving control unit 47 Memory unit (on-vehicle memory unit)
48 Obstacle determination unit 50 Obstacle detection unit 101 Relative position measurement unit (front lidar sensor)
102 Relative position measurement unit (rear lidar sensor)
103 Relative position measurement unit (right sonar unit)
104 Relative position measurement unit (left sonar unit)
200 Obstacle 201 Measurement object Ap1 Area specific point Ap2 Area specific point Ap3 Area specific point Ap4 Area specific point A2 Travel area AL Area specific line L Judgment reference line p0 Positioning target position

Claims (4)

an automatic driving control unit that automatically drives a work vehicle within a driving area in which a plurality of driving routes are arranged in parallel ;
a detection unit that detects the presence or absence of an object around the work vehicle,
The detection unit determines whether the position of the detected object is within the travel area.
An automated driving system for work vehicles. When the detection unit determines that the detected object is located within the travel area, the detection unit determines that the detected object is an obstacle.
The automatic driving system for a work vehicle according to claim 1 . When the detection unit determines that the detected object is located outside the traveling area, the detection unit excludes the detected object from an obstacle.
3. The automatic driving system for a work vehicle according to claim 1 or 2. When the detection unit determines that the detected object is located within the travel area, and determines that there is a part outside the travel area between the detected object and the work vehicle, the detection unit excludes the detected object from an obstacle.
The automatic driving system for a work vehicle according to any one of claims 1 to 3.