JP6976782B2 - Autonomous driving system for work vehicles - Google Patents

Description

The present invention relates to an autonomous traveling system for a passenger work vehicle such as a tractor, a passenger rice planting machine, a combine, a passenger grass mowing machine, a wheel loader, a snow removal vehicle, and a work vehicle that can be used for an unmanned work vehicle such as an unmanned mowing machine. Specifically, a storage unit that stores a target route generated in advance, a positioning unit that measures the current position and current orientation of the vehicle, and automatic steering of the steering wheels so that the vehicle autonomously travels on the target route. It relates to an autonomous driving system for a work vehicle equipped with an automatic steering unit.

In an autonomous traveling system for a work vehicle as described above, a geomagnetic orientation sensor that detects the orientation of the own vehicle, a GPS receiver that recognizes the current position of the own vehicle, and a steering angle sensor that detects the steering angle of the front wheels. While the work vehicle is autonomously traveling on a straight target route, the central part, which is the center position between the front wheels on the front side of the vehicle body, and the GPS position measurement point, which is the antenna installation position of the GPS receiver on the rear side of the vehicle body, are , When the front wheel is steered at an arbitrary steering angle while being laterally separated from the straight target path by the first or second distance, the straight target path from the center on the front side of the vehicle body is used. A target point is set on the straight target path three distances ahead of the intersection of the vertical line and the straight target path, and the straight line connecting the center and the target point and the straight line parallel to the straight target path passing through the center The front target azimuth (previous target azimuth = Arctan (1st distance / 3rd distance)) is calculated, and the target steering angle (target steering angle = azimuth +) is calculated by the azimuth of the vehicle body, the steering angle, and the target azimuth with respect to the straight target path. Steering angle + target direction) is calculated. In addition, a rear target point is set on the linear target path four distances forward from the intersection of the vertical line with respect to the linear target path from the GPS position measurement point and the linear target path, and a straight line connecting the GPS position measurement point and the rear target point is set. And the target azimuth (target azimuth = Arctan (second distance / fourth distance)) between the straight line target path passing through the GPS position measurement point and the parallel straight line is calculated. Then, the command value for front wheel steering that does not include the error of the geomagnetic orientation sensor is calculated from the steering control value based on the target steering angle of the front wheels and the proportional and integrated values of PI control based on the target orientation of the GPS position measurement point. By controlling the steering angle of the front wheels based on the command value and the output of the steering angle sensor so that the steering angle of the front wheels matches this command value, the vehicle is configured to autonomously travel along the target route. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-358122

In the configuration described in Patent Document 1, the steering angle error due to individual differences in the steering angle sensor is not taken into consideration in the automatic steering of the front wheels. Therefore, as shown in FIG. 9, the work vehicle 1 is used. Even if the target steering angle of the steering wheel is set to the target steering angle for straight travel while autonomously traveling on the straight work path portion P1 of the target route P, the actual steering angle of the steering wheel travels straight due to the steering angle error. The work vehicle 1 is gradually offset in the diagonal direction from the straight-ahead work path portion P1 according to the deviation amount at this time. After that, even if the target steering angle of the steering wheel is changed to the target steering angle for returning the work vehicle 1 to the straight path portion P1 based on the offset at this time, the change amount of the target steering angle at this time steers. This is offset by the angle error, and the work vehicle 1 travels with a constant travel offset amount So with respect to the straight-ahead work path portion P1. As a result, the work accuracy is lowered due to the running offset.

In view of this situation, a main problem of the present invention is to provide an autonomous traveling system for a work vehicle capable of suppressing a decrease in work accuracy due to a travel offset due to a steering angle error.

The first characteristic configuration of the present invention is
A storage unit that stores a target route generated in advance, a positioning unit that measures the current position and current direction of the own vehicle, and an automatic steering unit that automatically steers the steering wheels so that the own vehicle autonomously travels on the target route. And with
The automatic steering unit has a steering angle setting unit that sets a target steering angle of the steering wheel, and a steering angle sensor that detects the steering angle of the steering wheel.
The steering angle setting unit corrects the target steering angle with the steering angle calculating means for calculating the target steering angle, the steering angle error detecting means for detecting the steering angle error during autonomous driving, and the steering angle error. Has a rudder angle correction means,
The steering angle error detecting means includes a gaze point setting process for setting a gaze point on the target path at a certain distance from the current position on the traveling direction side during autonomous driving, and a line segment from the current position to the gaze point. A line segment generation process for generating a minute and a steering angle error calculation process for calculating the angle formed by the target path and the line segment as the steering angle error are performed.
The steering angle correction means is at a point of performing a correction process of adding the steering angle error obtained in the steering angle error calculation process to the target steering angle.

According to this configuration, the steering angle error detecting means can easily detect the steering angle error during autonomous driving by performing the above-mentioned gaze point setting processing, line segment generation processing, and steering angle error calculation processing. can. Then, the steering angle correction means can obtain a target steering angle in consideration of the steering angle error by performing the correction processing described above, and automatically steers the steering wheel based on the corrected target steering angle. As a result, it is possible to reduce the amount of travel offset with respect to the target route of the own vehicle during autonomous traveling due to the steering angle error.
As a result, it is possible to suppress a decrease in work accuracy due to a running offset due to the steering angle error while reducing the calculation load required for calculating the steering angle error.

The second characteristic configuration of the present invention is
The steering angle error detecting means has a detection condition determination process for determining whether or not a predetermined condition that allows detection of the steering angle error is satisfied, and the steering angle error until the predetermined condition is satisfied. The point is to perform a detection prohibition process that prohibits detection.

According to this configuration, the initial deviation that occurs immediately after the work vehicle starts autonomous driving is detected as a steering angle error by the steering angle error detecting means, so that the steering angle error detection accuracy is detected by the steering angle error detecting means. Can be prevented from decreasing.
As a result, the target steering angle is corrected by a steering angle error with low detection accuracy, and the steering wheel is automatically steered based on the corrected target steering angle. It is possible to avoid the occurrence of inconvenience that the traveling offset amount with respect to the route is unlikely to decrease.

The third characteristic configuration of the present invention is
In the detection condition determination process, the steering angle error detecting means determines that the predetermined condition is satisfied when the own vehicle travels a certain distance required from the start of autonomous driving to the setting of autonomous driving. It is in.

According to this configuration, the detection of the steering angle error is prohibited by the detection prohibition process from the time when the own vehicle starts autonomous driving until the vehicle travels a certain distance.
As a result, the steering angle error is detected and the target steering angle is corrected based on the detected steering angle error even during the period from the start of autonomous driving of the own vehicle to the setting of autonomous driving. The detection accuracy of the angle error is reduced, and the steering wheel is automatically steered based on the target steering angle corrected by the steering angle error with low detection accuracy. It is possible to avoid the inconvenience that the traveling offset amount is less likely to decrease.

The fourth characteristic configuration of the present invention is
The steering angle error detecting means detects the steering angle error a plurality of times until the own vehicle travels a set distance for detecting the steering angle error, and averages the steering angle errors for the plurality of times. The point is to obtain a value and perform an averaging process in which the average value is used as a steering angle error for the correction process.

According to this configuration, it is possible to increase the detection accuracy of the steering angle error by the steering angle error detecting means by the above-mentioned averaging process. Then, the steering wheel is automatically steered based on the target steering angle corrected by the steering angle error with high detection accuracy, so that the traveling offset amount with respect to the target path of the own vehicle during autonomous driving is reduced more reliably. be able to. As a result, it is possible to more effectively suppress the deterioration of work accuracy due to the traveling offset.

The fifth characteristic configuration of the present invention is
The steering angle error detecting means is at a point of re-detecting the steering angle error and updating the steering angle error every time the own vehicle travels a set distance for re-detecting the steering angle error during autonomous traveling.

According to this configuration, the steering angle error detecting means can increase the detection accuracy of the steering angle error every time the steering angle error is updated by the update process. Then, the steering wheel is automatically steered based on the target steering angle corrected by the steering angle error whose detection accuracy is increased at each update, so that the longer the autonomous mileage of the own vehicle is, the more the autonomous driving is performed. It is possible to reduce the amount of travel offset with respect to the target route of the own vehicle, and it is possible to more effectively suppress the decrease in work accuracy due to the travel offset.

The figure which shows the schematic structure of the autonomous driving system for a work vehicle. Block diagram showing the schematic configuration of an autonomous driving system for work vehicles A diagram showing an example of a target route generated for a work vehicle to travel autonomously in a field. Explanatory drawing about calculation of azimuth angle deviation in a state where a work vehicle is autonomously traveling straight on a work path. Explanatory drawing about calculation of azimuth angle deviation in a state where a work vehicle is autonomously traveling on a reverse straight path portion. Explanatory drawing about calculation of azimuth angle deviation in a state where a work vehicle is autonomously traveling on a turning path Detailed explanatory diagram regarding the calculation of the azimuth angle deviation in the state where the work vehicle is autonomously traveling on the turning path portion. Explanatory diagram for setting the target point Explanatory diagram showing a state in which the work vehicle is offset from the target route due to a steering angle error when the work vehicle is autonomously traveling. Explanatory drawing about detection of rudder angle error Flowchart for rudder angle error detection

An embodiment in which the autonomous traveling system for a work vehicle according to the present invention is applied to a tractor as an example of a work vehicle will be described with reference to the drawings.
The autonomous traveling system for a work vehicle according to the present invention includes passenger work vehicles such as a passenger rice transplanter, a combine, a passenger grass mowing machine, a wheel loader, and a snowplow, and unmanned work such as an unmanned mowing machine, other than a tractor. It can be applied to vehicles.

As shown in FIGS. 1 and 2, the autonomous traveling system for the work vehicle exemplified in the present embodiment is a mobile phone that is set to communicate with the autonomous traveling unit 2 mounted on the tractor 1 and the autonomous traveling unit 2. It is equipped with a communication terminal 3, and the like. As the mobile communication terminal 3, a tablet-type personal computer or a smartphone having a touch-operable liquid crystal panel 4 or the like can be adopted.

As shown in FIG. 1, the tractor 1 has a rotary tillage specification in which a rotary tiller 6 which is an example of a working device is connected to the rear portion via a three-point link mechanism 5 so as to be able to move up and down and roll. It is configured.
A working device such as a plow, a sowing device, a spraying device, or the like can be connected to the rear part of the tractor 1 instead of the rotary tilling device 6.

As shown in FIGS. 1 and 2, the tractor 1 includes left and right front wheels 7 that function as driveable steering wheels, driveable left and right rear wheels 8, a cabin 9 that forms a boarding-type driver, and a common rail system. An electronically controlled diesel engine (hereinafter referred to as an engine) 10, an electronically controlled transmission 11 that shifts the power from the engine 10, a fully hydraulic power steering mechanism 12 that steers the left and right front wheels 7, and left and right. Left and right side brakes (not shown) that brake the rear wheels 8, an electronically controlled brake operation mechanism 13 that enables hydraulic operation of the left and right side brakes, and a work clutch that interrupts transmission to the rotary tiller 6 (not shown). (Not shown), an electronically controlled clutch operating mechanism 14 that enables hydraulic operation of the work clutch, an electronically hydraulically controlled elevating drive mechanism 15 that elevates and drives the rotary tiller 6, and autonomous traveling of the own vehicle (tractor) 1. An in-vehicle electronic control unit (hereinafter referred to as an in-vehicle ECU) 16 having various control programs related to the above, a vehicle speed sensor 17 for detecting the vehicle speed of the own vehicle 1, a steering angle sensor 18 for detecting the steering angle of the front wheels 7, and the steering angle sensor 18. It is equipped with a positioning unit 19 that measures the current position and current orientation of the own vehicle 1, and the like.
An electronically controlled gasoline engine equipped with an electronic governor may be adopted as the engine 10. As the speed change device 11, a hydraulic mechanical type continuously variable transmission (HMT), a hydrostatic continuously variable transmission (HST), a belt type continuously variable transmission, or the like can be adopted. As the power steering mechanism 12, an electric power steering mechanism 12 provided with an electric motor or the like may be adopted.

As shown in FIG. 1, inside the cabin 9, a steering wheel 20 that enables manual steering of the left and right front wheels 7 via the power steering mechanism 12 and a seat 21 for the user are provided. Although not shown, the shift lever that enables manual operation of the transmission 11, the left and right brake pedals that enable artificial operation of the left and right side brakes, and the rotary tiller 6 can be manually raised and lowered. It is equipped with an elevating lever, etc.

As shown in FIG. 2, the in-vehicle ECU 16 controls a shift control unit 16A that controls the operation of the transmission device 11, a braking control unit 16B that controls the operation of the left and right side brakes, and a work device control that controls the operation of the rotary tiller 6. The unit 16C, the non-volatile in-vehicle storage unit 16D that stores the target path P for autonomous driving generated in advance, and the target steering angles θs of the left and right front wheels 7 during autonomous driving are set and output to the power steering mechanism 12. It has a steering angle setting unit 16E and the like.

As shown in FIGS. 1 to 3, the positioning unit 19 uses GPS (Global Positioning System), which is an example of the Global Navigation Satellite System (GNSS), to set the current position p1 of the own vehicle 1. An inertial measurement unit (IMU) that measures the attitude and orientation of the vehicle 1 with a satellite navigation device 22 that measures the current orientation θ1 and a 3-axis gyroscope and 3-direction acceleration sensors. ) 23, etc. are provided. Positioning methods using GPS include DGPS (Differential GPS: relative positioning method) and RTK-GPS (Real Time Kinematic GPS: interference positioning method). In this embodiment, RTK suitable for positioning a moving object is used. -GPS is adopted. Therefore, a reference station 24 that enables positioning by RTK-GPS is installed at a known position around the field.

Each of the tractor 1 and the reference station 24 is capable of wireless communication of various data including positioning data between the GPS antennas 26 and 27 that receive radio waves transmitted from the GPS satellite 25 and the positioning data between the tractor 1 and the reference station 24. Communication modules 28, 29, etc. are provided. As a result, the satellite navigation device 22 receives the positioning data obtained by the GPS antenna 26 on the tractor side receiving the radio waves from the GPS satellite 25 and the GPS antenna 27 on the base station side receiving the radio waves from the GPS satellite 25. Based on the obtained positioning data, the current position p1 and the current direction θ1 of the own vehicle 1 can be measured with high accuracy. Further, the positioning unit 19 is provided with the satellite navigation device 22 and the inertial measurement unit 23, so that the current position p1, the current direction θ1, and the attitude angle (yaw angle, roll angle, pitch angle) of the own vehicle 1 can be set with high accuracy. Can be measured.

As shown in FIGS. 2 to 3, the mobile communication terminal 3 includes a terminal electronic control unit (hereinafter referred to as a terminal ECU) 30 having various control programs for controlling the operation of the liquid crystal panel 4 and the like, and a tractor side. A communication module 31 that enables wireless communication of various data including positioning data with the communication module 28 of the above is provided. The terminal ECU 30 is a non-volatile terminal that stores a target route generation unit 30A that generates a target route P for autonomous driving, various input data input by the user, a target route P generated by the target route generation unit 30A, and the like. It has a storage unit 30B, etc.

As shown in FIGS. 1 to 3, the target route generation unit 30A follows the input guidance for target route generation displayed on the liquid crystal panel 4, and provides vehicle body data such as the type and model of the work vehicle and the work device, and the work. When the target field position and the like are input by the user, it is determined whether or not the corresponding target route P is stored in the terminal storage unit 30B based on the input vehicle body data and the field position and the like. When the corresponding target route P is stored, the target route P is read out from the terminal storage unit 30B and displayed on the liquid crystal panel 4. If the corresponding target route P is not stored, the liquid crystal panel 4 displays the execution guide of the positioning data acquisition run for obtaining the positioning data necessary for generating the target route P, and the user performs the positioning data acquisition run. Let me. Then, based on the positioning data obtained by wireless communication with the tractor 1 during the positioning data acquisition running, the field data such as the section and shape of the work target field is acquired, and the acquired field data and the vehicle body data are obtained. Based on the minimum turning radius, the working width, and the like included in the tractor 1, a target path P suitable for working on the field to be worked on is generated by the tractor 1. Then, the generated target route P is displayed on the liquid crystal panel 4, and is stored in the terminal storage unit 30B as route data associated with vehicle body data, field data, and the like. The route data includes the azimuth angle θp of the target route P, the target engine speed and the target vehicle speed set according to the traveling mode of the tractor 1 on the target route P, and the like.

As shown in FIG. 3, in the present embodiment, a field partitioned in a rectangular shape is exemplified as a field to be worked. Further, as a target path P suitable for this rectangular field, a plurality of straight-ahead work path portions P1 having the same straight-ahead distance and arranged in parallel with a certain distance corresponding to the work width, and adjacent straight-ahead paths P1. An example is a reciprocating travel route in which the tractor 1 is reciprocated from the start point Ps of the target route P to the end point Pe by providing a plurality of direction change route portions P2 extending over the end point P1e of the work route unit P1 and the start point P1s. ing. Of the plurality of straight-ahead work path portions P1, the odd-numbered row is the outward route portion and the even-numbered row is the return route portion. The plurality of turning path portions P2 include a first turning path section P3 that turns the tractor 1 by 90 degrees from the terminal point P1e of the straight working path section P1 toward the next straight working path section, and a first turning path section P3. The start end of the next straight work path section P1 from the reverse end point P4e of the backward straight path section P4 that causes the tractor 1 to go straight backward from the turning end point P3e of the previous turn toward the previous straight work path section side. It is partitioned into a second turning path portion P5 that turns the tractor 1 90 degrees toward the point P1s.
That is, the target route P is divided into a plurality of types of route portions P1 to P5 according to the traveling mode of the own vehicle 1.
The target route P shown in FIG. 3 is merely an example, and the target route P is, for example, a plurality of direction change route portions P2 from the end point P1e of the straight work route unit P1 to the start end of the next straight work route unit P1. It may be generated to include a U-turn path portion that turns the tractor 1 180 degrees toward the point P1s.

As shown in FIGS. 2 to 3, when the target path P is confirmed and displayed on the liquid crystal panel 4, the terminal ECU 30 is instructed to execute autonomous driving by the operation of the liquid crystal panel 4 by the user. The target route P being displayed together with the execution command is transmitted to the vehicle-mounted ECU 16 via the communication modules 31 and 28.
Regarding the transmission of the target route P, the entire target route P may be transmitted from the terminal ECU 30 to the vehicle-mounted ECU 16 at once before the tractor 1 starts autonomous traveling. Further, for example, in the stage before the target route P is divided into a plurality of route portions for each predetermined distance with a small amount of data and the tractor 1 starts autonomous traveling, only the initial route portion of the target route P is the terminal ECU 30. Is transmitted from the terminal ECU 30 to the vehicle-mounted ECU 16, and every time the tractor 1 reaches a route acquisition point set according to the amount of data or the like, only the subsequent route portion corresponding to that point is transmitted from the terminal ECU 30 to the vehicle-mounted ECU 16. It may be sent to.

When the in-vehicle ECU 16 receives an execution command for autonomous travel and a target route P from the terminal ECU 30, the in-vehicle ECU 16 stores the received target route P in the in-vehicle storage unit 16D to check the amount of data, and after the confirmation, the own vehicle 1 Is started to autonomously travel based on the target route P or the like stored in the vehicle-mounted storage unit 16D.

The autonomous driving control includes automatic shift control that automatically controls the operation of the transmission, automatic braking control that automatically controls the operation of the brake operation mechanism 13, automatic steering control that automatically steers the left and right front wheels 7, and a rotary tiller. It includes automatic control for work that automatically controls the operation of 6.
In the automatic shift control, the shift control unit 16A determines the traveling mode of the tractor 1 on the target route P based on the target path P including the target vehicle speed, the output of the positioning unit 19, and the output of the vehicle speed sensor 17. The operation of the transmission 11 is automatically controlled so that the target vehicle speed set accordingly is obtained as the vehicle speed of the own vehicle 1.
In the automatic braking control, the braking control unit 16B causes the left and right side brakes to properly apply the left and right rear wheels 8 in the braking region included in the target path P based on the target path P and the output of the positioning unit 19. The operation of the brake operation mechanism 13 is automatically controlled so as to brake.
In the automatic steering control, the steering angle setting unit 16E sets the target steering angle θs of the left and right front wheels 7 based on the target path P and the output of the positioning unit 19 so that the own vehicle 1 autonomously travels on the target route P. It is obtained and set, and the set target steering angle θs is output to the power steering mechanism 12. Then, the power steering mechanism 12 automatically steers the left and right front wheels 7 so that the target steering angle θs is obtained as the steering angles of the left and right front wheels 7 based on the target steering angle θs and the output of the steering angle sensor 18.
In the automatic work control, the work device control unit 16C is a rotary tiller as the own vehicle 1 reaches the start point P1s of the straight work path unit P1 based on the target route P and the output of the positioning unit 19. The clutch operation mechanism 14 and the elevating drive mechanism 15 are so that the tillage by the rotary tiller 6 is stopped as the tillage by the rotary tiller 6 is started and the tillage by the rotary tiller 6 is stopped as the own vehicle 1 reaches the terminal point P1e of the straight work path portion P1. Automatically controls the operation of.

That is, in this tractor 1, the transmission 11, the power steering mechanism 12, the brake operation mechanism 13, the clutch operation mechanism 14, the elevating drive mechanism 15, the in-vehicle ECU 16, the vehicle speed sensor 17, the steering angle sensor 18, the positioning unit 19, and the like. The autonomous traveling unit 2 is composed of a communication module 28 and the like. Further, an automatic steering unit 32 that automatically steers the left and right front wheels 7 so that the own vehicle 1 autonomously travels on the target path P is configured by the power steering mechanism 12, the vehicle-mounted ECU 16, and the steering angle sensor 18.

The setting of the target steering angle θs will be described in detail. As shown in FIGS. 2 to 7, the steering angle setting unit 16E has a steering angle calculation means 16Ea for calculating the target steering angle θs during autonomous driving. The steering angle calculation means 16Ea performs a target point setting process for setting a target point p2 on a target path having a predetermined distance D1 on the traveling direction side from the current position p1 of the own vehicle 1 during autonomous driving, and a current position of the own vehicle 1. Performs line segment generation processing for generating a line segment L1 from position p1 to target point p2, and target steering angle calculation processing for calculating the angle formed by the current direction θ1 of the own vehicle 1 and the line segment L1 as the target steering angle θs. ..

The target steering angle calculation process will be described in detail. In the target steering angle calculation process, as shown in FIGS. If the direction (direction of the line segment L1) from the current position p1 of the own vehicle 1 to the target point p2 is the target azimuth angle θ2, and the angle formed by the target path P and the line segment L1 is the travel correction angle θc, the vehicle travels straight. The target azimuth angle θ2 in the work path portion P1 is
Target azimuth θ2 = azimuth θp1 of straight work path P1 + travel correction angle θc
Therefore, the target azimuth angle θ2 in the backward straight path portion P4 is
Target azimuth θ2 = azimuth θp4 of the backward straight path portion P4 + travel correction angle θc
Will be.
Here, the azimuth angle θp1 of the straight-ahead work path portion P1 and the azimuth angle θp4 of the backward straight-ahead path section P4 are known at the stage of generating the target path P, but when calculating these, the straight-ahead work path section P1 If the E component (x component) of the vector V1 from the start point P1s to the end point P1e is V1e and the N component (y component) of the vector V1 is V1n.
Azimuth θp1 = atan2 (V1e, V1n) of the straight work path portion P1
Will be. Further, if the E component (x component) of the vector V4 from the start position to the end position of the backward straight path portion P4 is V4e and the N component (y component) of the vector V4 is V4n,
Azimuth θp4 = atan2 (V4e, V4n) of the backward straight path portion P4
Will be. As for the travel correction angle θc, if the lateral deviation from the travel path of the own vehicle 1 on the NED coordinates is D2, the predetermined distance for setting the target point is D1.
Travel correction angle θc = asin (lateral deviation D2 / predetermined distance D1)
Therefore, the target azimuth angle θ2 can be obtained, and the target steering angle θs is obtained from the difference between the obtained target azimuth angle θ2 and the attitude angle (yaw angle) θ1 of the own vehicle 1 measured by the positioning unit 19. Can be done.
On the other hand, as shown in FIGS. 6 to 7, if the current traveling path of the own vehicle 1 is the first turning path portion P3 or the second turning path section P5, the turning center pt of each of the turning path sections P3 and P5. Assuming that the angle formed by the vector Vv from the vehicle 1 to the vehicle 1 and the N-axis is θv, the target steering angle θs is obtained from the above-mentioned angle θv, the current direction θ1 of the vehicle 1, and the travel correction angle θc.
Target steering angle θs = angle θv + SignTrn × 90-current direction θ1 + SignTrn × (90-travel correction angle θc)
Can be obtained by.
Here, degrees are used for all the units in this formula, and "90" in the formula indicates 90 degrees. Further, regarding "SignTrn", it is "1" if the turning direction is a clockwise direction, and "-1" if the turning direction is a counterclockwise direction. The travel correction angle θc in the above equation is the predetermined distance D1 for setting the target point, the distance D3 from the turning center pt of the turning path portions P3 and P5 to the own vehicle 1, and the turning of the turning path portions P3 and P5. From the radius R
Travel correction angle θc = acos ((D3 ^ 2 + D1 ^ 2-R ^ 2) / (2 × D3 × D1)
The distance D3 from the turning center pt of the turning path portions P3 and P5 to the own vehicle 1 in this equation is the turning radius R of the turning path portions P3 and P5 and the own vehicle 1 on the NED coordinates. From the lateral deviation D2 from the turning path portions P3 and P5,
Distance D3 = turning radius R + lateral deviation D2
Can be obtained by.
That is, it is possible to reduce the calculation load applied to the steering angle calculation means 16Ea in the target steering angle calculation process described above.

As shown in FIGS. 4 to 7, the vehicle-mounted storage unit 16D has a plurality of predetermined distances D1a to D1c for setting target points set to different lengths according to the types of the route units P1 to P5 in the target route P. Is remembered. The steering angle calculation means 16Ea automatically changes the predetermined distance D1 for setting the target point in the target point setting process according to the types of the route portions P1 to P5 on which the own vehicle 1 autonomously travels on the target route P.
This eliminates the need for the user to manually change the predetermined distance D1 according to the types of the path portions P1 to P5 on which the tractor 1 autonomously travels. Further, it is possible to prevent a decrease in the calculation accuracy of the target steering angle θs due to the user making a mistake in the predetermined distance D1 or forgetting to change the predetermined distance D1.

Regarding the predetermined distance D1 for setting the target point, the steering angle calculation means 16Ea sets the predetermined distance D1 when the current position p1 of the own vehicle 1 is the straight work path portion P1 as shown in FIG. The distance is changed to the first predetermined distance D1a suitable for autonomous traveling on the straight work path portion P1.
As shown in FIG. 5, when the current position p1 of the own vehicle 1 is the rear straight path portion P4, the steering angle calculation means 16Ea autonomously travels the predetermined distance D1 by the rear straight path portion P4. Change to the second predetermined distance D1b suitable for. The second predetermined distance D1b becomes rear steering for steering the left and right front wheels 7 on the rear side of the traveling direction when the own vehicle 1 corrects the traveling direction in the autonomous traveling on the rear straight path portion P4, and is lateral to the vehicle body. The distance is set to be longer than the first predetermined distance D1a in consideration of the large amount of runout.
As shown in FIGS. 6 to 7, when the current position p1 of the own vehicle 1 is the first turning path portion P3 or the second turning path portion P5, the steering angle calculating means 16Ea sets the predetermined distance D1 by the own vehicle 1. The first turning path section P3 or the second turning path section P5 is changed to a third predetermined distance D1c suitable for autonomous traveling. The third predetermined distance D1c is the first in consideration of the fact that the own vehicle 1 is easily separated from the turning path portions P3 and P5 in the autonomous traveling in the first turning path portion P3 or the second turning path portion P5. It is set to a distance shorter than the predetermined distance D1a and the second predetermined distance D1b.

As shown in FIG. 8, in the steering angle calculation means 16Ea, the current position p1 of the own vehicle 1 is different from the current path portion (for example, the straight-ahead work path portion P1) to the next path portion (for example, the first turning path portion P3). ), The target point p2 is set on the extension of the current route section.
Thereby, for example, while the own vehicle 1 is autonomously traveling on the straight-ahead work path portion P1, a target point p2 suitable for autonomous travel on the straight-ahead work path portion P1 can be set, and the target point p2 can be set from this target point p2. It is possible to calculate a target steering angle θs suitable for autonomous driving in the straight-ahead work path portion P1. Further, while the own vehicle 1 is autonomously traveling on the first turning path portion P3, a target point p2 suitable for autonomous traveling on the first turning path portion P3 can be set, and the target points p2 to the first It is possible to calculate a target steering angle θs suitable for autonomous driving in one turning path portion P3. As a result, it is possible to improve the traveling accuracy when the own vehicle 1 autonomously travels on the target route P.

By the way, as shown in FIG. 9, in a work vehicle such as a tractor 1, a rudder angle error θe due to an individual difference of the rudder angle sensor 18 is included in the steering system, so that the rudder is steered during autonomous driving. Due to the angle error θe, the work vehicle travels with a constant travel offset amount So with respect to the target route P. As a result, the work accuracy is lowered due to the running offset.

Therefore, as shown in FIG. 2, the steering angle setting unit 16E uses the steering angle error detecting means 16Eb for detecting the steering angle error θe during autonomous driving and the steering angle error θe in addition to the steering angle calculating means 16Ea. It has a steering angle correction means 16Ec that corrects the target steering angle θs.

As shown in FIGS. 10 to 11, the steering angle error detecting means 16Eb is on the traveling direction side from the current position p1 of the own vehicle 1 when the own vehicle 1 is autonomously traveling straight on the straight-ahead work path portion P1 of the target route P. The gaze point setting process (step # 3) for setting the gaze point p3 on the target route with a certain distance D4 on the (front side), and the line segment L2 from the current position of the own vehicle 1 to the gaze point p3. The minute generation process (step # 4) and the steering angle error calculation process (step # 5) for calculating the angle formed by the target path P and the line segment L2 as the steering angle error θe are performed. Then, in the rudder angle error calculation process, if the lateral deviation of the own vehicle 1 from the straight-ahead work path portion P1 on the NED coordinates is D5, the constant distance for setting the gaze point is D4, so that the rudder is steered. Angle error θe,
Steering angle error θe = asin (lateral deviation D5 / constant distance D4)
Can be obtained by.
The steering angle correction means 16Ec performs a correction process of adding the steering angle error θe obtained by the above-mentioned steering angle error calculation process to the target steering angle θs obtained by the above-mentioned target steering angle calculation process.
As a result, the target steering angle θs can be corrected to a value in consideration of the steering angle error θe, and by outputting the target steering angle θs after this correction process to the power steering mechanism 12, the own vehicle during autonomous driving It is possible to reduce the traveling offset amount So with respect to the target route P of 1. As a result, it is possible to suppress a decrease in work accuracy due to a traveling offset.

As shown in FIGS. 3 and 10 to 11, the steering angle error detecting means 16Eb determines whether or not a predetermined condition that allows detection of the steering angle error θe is satisfied (step # 1). And the detection prohibition process (step # 2) for prohibiting the detection of the steering angle error θe is performed until the predetermined condition is satisfied.
In the present embodiment, as a predetermined condition, it is set whether or not the own vehicle 1 has traveled a certain distance La required from the start of autonomous traveling on the straight-ahead work path portion P1 until the autonomous traveling is settled. .. Then, in the detection condition determination process, the steering angle error detecting means 16Eb states that the predetermined condition is satisfied when the own vehicle 1 runs autonomously on the straight-ahead work path portion P1 and then runs a certain distance La. It is configured to make a judgment, and as a result, the steering angle error θe is determined by the detection prohibition process from the time when the own vehicle 1 starts autonomous driving on the straight work path portion P1 until the vehicle travels a certain distance La. Detection is prohibited.
As a result, the steering angle error θe is detected and the target steering based on the detected steering angle error θe is detected even after the own vehicle 1 starts autonomous traveling on the straight work path portion P1 until the autonomous traveling is settled. By correcting the angle θs, the detection accuracy of the steering angle error θe decreases, and the target steering angle θs is corrected based on the steering angle error θe with low detection accuracy and output to the power steering mechanism 12. Therefore, it is possible to avoid the inconvenience that the traveling offset amount So with respect to the target route P of the own vehicle 1 is less likely to decrease during autonomous traveling.

As shown in FIGS. 3 and 11, the steering angle error detecting means 16Eb determines whether or not the own vehicle 1 has traveled the first set distance Lb for detecting the steering angle error after traveling a certain distance La. The running determination process (step # 6) is performed, and the steering angle error θe is detected every set time until the own vehicle 1 runs through the first set distance Lb for detecting the steering angle error, and the own vehicle 1 An averaging process in which the average value of the steering angle error θe for a plurality of times detected for each set time is obtained as the vehicle runs through the first set distance Lb, and this average value is used as the steering angle error θe for correction processing. (Step # 7) is performed.
This makes it possible to increase the detection accuracy of the steering angle error θe by the steering angle error detecting means 16Eb. Then, the steering angle correction means 16Ec outputs the target steering angle θs corrected by the highly accurate steering angle error θe to the power steering mechanism 12, so that the travel offset amount So with respect to the target path P of the own vehicle 1 during autonomous driving. Can be lowered more reliably. As a result, it is possible to more effectively suppress the deterioration of work accuracy due to the traveling offset.

The steering angle error detecting means 16Eb is a second running determination process (step # 9) for determining whether or not the own vehicle 1 has traveled a second set distance Lc for rediscovering a steering angle error longer than the first set distance Lb. ), And every time the own vehicle 1 runs through the second set distance Lc, the average value of the steering angle error θe is rediscovered and the steering angle error θe is updated based on the above-mentioned processing procedure.
As a result, the steering angle error detecting means 16Eb can increase the detection accuracy of the steering angle error θe every time the steering angle error θe is updated by the update process, and the steering angle correction means 16Ec can increase the accuracy every time the steering angle error θe is updated. The target steering angle θs corrected based on the steering angle error θe can be output to the power steering mechanism 12. As a result, as the autonomous mileage in the straight-ahead work path portion P1 of the own vehicle 1 becomes longer, the travel offset amount So with respect to the target route P of the own vehicle 1 during autonomous travel can be reduced, and the work accuracy due to the travel offset can be reduced. The decrease can be suppressed more effectively.
The difference between the first set distance Lb for detecting the steering angle error and the second set distance Lc for re-detecting the steering angle error is the target steering based on the steering angle error θe obtained by traveling at the first set distance Lb. In autonomous driving by automatic steering after the angle θs is corrected, the setting is made in consideration of the mileage until the autonomous driving is settled.

As shown in FIG. 11, the steering angle error detecting means 16Eb is a route unit that determines whether or not the own vehicle 1 has shifted from the straight-ahead work route unit P1 to the direction change route unit P2 during the execution of the above-mentioned averaging process. The transition determination process (step # 8) is performed, and when the transition is performed, the averaging process at this time is terminated and the averaging stop process (step # 10) is performed without obtaining the average value of the steering angle error θe.
As a result, in the averaging process of the rudder angle error θe, the rudder angle error θe at the time of turning has a component different from the rudder angle error θe at the time of straight running, and the rudder angle error θe at the time of straight running is mixed with the rudder. It is possible to prevent a decrease in the detection accuracy of the angle error θe.

Although not shown, the steering angle error detecting means 16Eb determines whether the straight work path portion P1 this time is an odd row or an even row each time the own vehicle 1 starts autonomous traveling in each straight work path portion P1. If several rows are discriminated and the straight-ahead work path portion P1 this time is an even-numbered row (outward route portion), the steering angle error θe detected during autonomous driving in the straight-ahead work route portion P1 this time is the steering angle error for the outward route. In the update process described above, θe is set, and the steering angle error θe for the outward route is updated every time the steering angle error θe for the outward route is detected. Further, if the straight-ahead work path section P1 this time is an even-numbered row (return path section), the steering angle error θe detected during autonomous driving in the straight-ahead work path section P1 this time is defined as the steering angle error θe for the return path, as described above. In the update process, the steering angle error θe for the return route is updated every time the steering angle error θe for the return route is detected.
Based on the discrimination result obtained in the sequence discrimination process described above, the steering angle correction means 16Ec performs the target steering angle calculation process described above for the steering angle error θe for the outward route if the straight-ahead work path portion P1 this time has an odd number of rows. The correction process for the outward route is performed by adding to the target steering angle θs obtained in. Further, if the straight-ahead work path portion P1 this time is an even number of rows, a correction process for the return path is performed by adding the steering angle error θe for the return path to the target steering angle θs obtained by the target steering angle calculation process described above.
As a result, due to an error in the yaw angle of the own vehicle 1 measured by the positioning unit 19, the own vehicle 1 autonomously travels on the straight work path portion (outward route portion) P1 in an odd row, and evenly. When there is a difference in the steering angle error θe between the case of autonomously traveling on the straight work path portion (return route portion) P1 of the row, the steering angle error θe for the outward route is updated by the steering angle error θe for the return route. Alternatively, it is possible to prevent a decrease in the detection accuracy of the steering angle error θe due to the update of the steering angle error θe for the return route by the steering angle error θe for the outward route.
Specifically, for example, in a field where the direction of the odd-numbered straight work path section (outward path section) P1 is directly north and the even-numbered row straight-line work path section (return path section) P1 is directly south. When the vehicle 1 is autonomously traveling on the straight work path portion (outward route portion) P1 in an odd row, the direction of the own vehicle 1 measured by the positioning unit 19 is 0 degrees, and the own vehicle 1 is in an even row. When the vehicle is autonomously traveling on the straight-ahead work route portion (return route portion) P1, the orientation of the own vehicle 1 measured by the positioning unit 19 is ideally 180 degrees, but in reality, the positioning unit Positioning despite the fact that the own vehicle 1 is autonomously traveling on the even-numbered straight work path portion (outward route portion) P1 due to an error in the yaw angle of the own vehicle 1 measured by 19. Positioning may occur even though the direction of the own vehicle 1 measured by the unit 19 may deviate slightly from 0 degrees, and the own vehicle 1 autonomously travels on the even-numbered straight work path portion (return route portion) P1. The direction of the own vehicle 1 measured by the unit 19 may deviate slightly from 180 degrees.
As a result, originally, the direction of the own vehicle 1 when the own vehicle 1 is autonomously traveling on the odd-numbered row of straight-ahead work path portion (outward route portion) P1 and the own vehicle 1 is an even-numbered row of straight-ahead work route portion (return route). Part) The angle difference from the direction of the own vehicle 1 when autonomously traveling on P1 should be 180 degrees, but there may be a problem that the angle difference is not 180 degrees due to the positioning error.
However, when the own vehicle 1 autonomously travels on the straight work path portion P1 in the same odd-numbered row or the same even-numbered row, the deviation direction of the orientation due to the positioning error tends to be constant. , The steering angle error θe for odd-numbered rows (for the outward route) and the steering angle error θe for the even-numbered rows (for the return route) are individually detected and updated individually.
As a result, it is possible to obtain a steering angle error θe for the outward route and a steering angle error θe for the return route with high detection accuracy.
If the straight-ahead work path portion P1 in which the own vehicle 1 autonomously travels is the outward path portion, the target steering angle θs at this time can be corrected to a value in consideration of the steering angle error θe for the outward path, and this correction can be made. By outputting the subsequent target steering angle θs to the power steering mechanism 12, the traveling offset amount So with respect to the straight-ahead work path portion P1 of the own vehicle 1 during autonomous driving in the straight-ahead work path portion P1 for the outward route is more preferably reduced. Can be made to. Further, if the straight-ahead work path portion P1 in which the own vehicle 1 autonomously travels is a return path portion, the target steering angle θs at this time can be corrected to a value in consideration of the steering angle error θe for the return path, and this correction can be made. By outputting the subsequent target steering angle θs to the power steering mechanism 12, the traveling offset amount So with respect to the straight-ahead work path portion P1 of the own vehicle 1 during autonomous driving in the straight-ahead work path portion P1 for the return route is more preferably reduced. Can be made to.

The steering angle error detecting means 16Eb performs a storage process of storing the latest steering angle error θe in the vehicle-mounted storage unit 16D every time the steering angle error θe is detected or updated, and the steering angle correcting means 16Ec performs the detection prohibition process described above. While the detection of the steering angle error θe is prohibited, the target steering angle θs obtained by the target steering angle calculation process is corrected by the steering angle error θe stored in the vehicle-mounted storage unit 16D.
As a result, even during autonomous driving in which the detection of the steering angle error θe is prohibited by the detection prohibition process, the target steering angle θs obtained by the target steering angle calculation process can be corrected to a value in consideration of the steering angle error θe. By outputting the target steering angle θs after this correction process to the power steering mechanism 12, the traveling offset amount So with respect to the target path P of the own vehicle 1 can be reduced.
Further, as described above, since the vehicle-mounted storage unit 16D is non-volatile, even when the key-on operation is performed and autonomous driving is started after the power is turned off by the key-off operation of the own vehicle 1. The target steering angle θs obtained by the target steering angle calculation process can be corrected by the steering angle error θe stored in the vehicle-mounted storage unit 16D, and the traveling offset amount So with respect to the target path P of the own vehicle 1 can be reduced. can.

[Another Embodiment]
Other embodiments of the present invention will be described.
It should be noted that the configurations of the respective embodiments described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments.

(1) The configuration of the work vehicle can be changed in various ways.
For example, the work vehicle may be configured to have a hybrid specification including an engine 10 and an electric motor for traveling, or may be configured to have an electric specification including an electric motor for traveling instead of the engine 10. ..
For example, the work vehicle may be configured to have a semi-crawler specification in which left and right crawlers are provided instead of the left and right rear wheels 8.
For example, the work vehicle may be configured with rear wheel steering specifications in which the left and right rear wheels 8 function as steering wheels.

(2) If the automatic steering unit 32 is configured to interlock the steering wheel 20 and the left and right front wheels (steering wheels) 7 by mechanical linkage, the steering angle sensor 18 can be used for the rotation operation direction and the rotation operation amount of the steering wheel 20. It may be configured to detect the steering angle of the front wheel (steering wheel) 7 based on the above.

(3) In the detection condition determination process, the steering angle error detecting means 16Eb satisfies a predetermined condition when the own vehicle 1 travels until a certain time required from the start of autonomous driving to the setting of autonomous driving elapses. It may be configured to detect the steering angle error θe by determining that the steering angle error θe has been detected.

(4) In the detection condition determination process, the steering angle error detecting means 16Eb determines that the predetermined condition is satisfied when the own vehicle 1 travels a set distance set according to the vehicle speed from the start of autonomous driving. It may be configured to detect the steering angle error θe.

(5) In the detection condition determination process, the rudder angle error detecting means 16Eb uses the rudder angle error θe obtained by the above-mentioned gaze point setting process, line segment generation process, and rudder angle error calculation process for detecting the rudder angle error. When the value drops below the set value, it may be determined that the predetermined condition is satisfied and the steering angle error θe may be detected.

(6) In the detection condition determination process, the steering angle error detecting means 16Eb determines a predetermined condition when it detects that the own vehicle 1 is autonomously traveling in parallel with the target route P based on the measurement of the positioning unit 19. It may be configured to detect the steering angle error θe by determining that is satisfied.

(7) In the averaging process, the rudder angle error detecting means 16Eb detects the rudder angle error θe a plurality of times until the set time for detecting the rudder angle error elapses, and the rudder angle error θe is detected a plurality of times. The average value of the angle error θe may be configured to be the steering angle error θe for correction processing.

(8) The steering angle error detecting means 16Eb may be configured not to perform the above-mentioned averaging process.

(9) The steering angle error detecting means 16Eb rediscovers the average value of the steering angle error θe or the steering angle error θe every time the set time for re-detecting the steering angle error elapses during autonomous driving, and the steering angle error. It may be configured to update θe.

(10) The steering angle error detecting means 16Eb re-detects the average value of the steering angle error θe or the steering angle error θe every time the own vehicle 1 travels a set distance set according to the vehicle speed, and the steering angle error. It may be configured to update θe.

(11) The interval (travel distance, time, etc.) in which the steering angle error detecting means 16Eb rediscovers the average value of the steering angle error θe or the steering angle error θe and updates the steering angle error θe is set by the mobile communication terminal 3 or the like. It may be configured so that the setting can be arbitrarily changed by an operation. In this configuration, the update interval of the steering angle error θe can be optimized according to the field conditions and the like.

(12) The steering angle error detecting means 16Eb stops the detection of the steering angle error θe when the deviation of the own vehicle 1 with respect to the target path P suddenly changes by a set value or more while the steering angle error θe is being detected. Then, when it is determined in the detection condition determination process described above that the predetermined condition is satisfied, the detection of the steering angle error θe may be restarted. In this configuration, it is possible to prevent the steering angle error θe based on a sudden change in deviation from being used to correct the target steering angle θs.

(13) The steering angle error detecting means 16Eb individually detects each steering angle error θe according to the traveling mode such as forward movement, reverse movement, turning, etc. of the own vehicle 1 during autonomous driving, and the vehicle-mounted storage unit 16D or the like. It may be configured to be stored in. This configuration is suitable when the steering angle error θe changes according to the traveling mode of the own vehicle 1.

(14) The steering angle error detecting means 16Eb rediscovers the steering angle error θe and updates the steering angle error θe when the update of the steering angle error θe is commanded by the operation of the mobile communication terminal 3 or the like. It may be configured. In this configuration, for example, when the work vehicle 1 cannot autonomously travel on the target route P with high accuracy, and the wheel diameter and wheel contact width change due to replacement of the wheels 7 and 8 in the work vehicle 1, or left and right. When the traveling characteristics are changed by changing the rear wheel 8 to a crawler, the steering angle error θe can be arbitrarily updated by operating the mobile communication terminal 3 or the like.

(15) It is detected that the work vehicle 1 has undergone a change in vehicle condition that affects the steering angle error θe, such as replacement of wheels 7 and 8 or change of left and right rear wheels 8 to crawlers. A sensor may be provided so that the steering angle error detecting means 16Eb automatically updates the steering angle error θe when the sensor detects a change in the vehicle state.

1 Own vehicle 7 Steering wheel 16D Storage unit 16E Steering angle setting unit 16Ea Steering angle calculating means 16Eb Steering angle error detecting means 16Ec Steering angle correction means 18 Steering angle sensor 19 Positioning unit 32 Automatic steering unit L2 Line division La For autonomous driving setting Constant distance Lb Set distance for rudder angle error detection Lc Set distance for rudder angle error rediscovery P Target path p1 Current position p3 Gaze point θ1 Current direction θe Rudder angle error θs Target steering angle

Claims (5)

A storage unit that stores a target route generated in advance, a positioning unit that measures the current position and current direction of the own vehicle, and an automatic steering unit that automatically steers the steering wheels so that the own vehicle autonomously travels on the target route. And with
The automatic steering unit has a steering angle setting unit that sets a target steering angle of the steering wheel, and a steering angle sensor that detects the steering angle of the steering wheel.
The steering angle setting unit includes a steering angle calculating means for calculating the target steering angle, a steering angle error detecting means for detecting a steering angle error included in the output of the steering angle sensor during autonomous driving, and the steering angle error. Has a steering angle correction means for correcting the target steering angle.
The steering angle error detecting means, in autonomous, and the is in constant predetermined distance from the current position, and the fixation point setting processing for setting a point on the target path including the traveling direction side as the gaze point, A line segment generation process for generating a line segment from the current position to the gaze point and a steering angle error calculation process for calculating the angle formed by the target path and the line segment as the steering angle error are performed.
The steering angle correction means is an autonomous traveling system for a work vehicle, which performs correction processing for adding the steering angle error obtained in the steering angle error calculation processing to the target steering angle. The steering angle error detecting means has a detection condition determination process for determining whether or not a predetermined condition that allows detection of the steering angle error is satisfied, and the steering angle error until the predetermined condition is satisfied. The autonomous traveling system for a work vehicle according to claim 1, wherein the detection prohibition process for prohibiting detection is performed. In the detection condition determination process, the steering angle error detecting means determines that the predetermined condition is satisfied when the own vehicle travels a certain distance required from the start of autonomous driving to the setting of autonomous driving. The autonomous traveling system for the work vehicle according to Item 2. The steering angle error detecting means detects the steering angle error a plurality of times until the own vehicle travels a set distance for detecting the steering angle error, and averages the steering angle errors for the plurality of times. The autonomous traveling system for a work vehicle according to any one of claims 1 to 3, wherein a value is obtained and an averaging process is performed in which the average value is used as a steering angle error for correction processing. The steering angle error detecting means claims 1 to re-detect the steering angle error and update the steering angle error every time the own vehicle travels a set distance for re-detecting the steering angle error during autonomous driving. The autonomous traveling system for the work vehicle according to any one of 4.

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