JP2019053471A - Work vehicle-purpose autonomous travelling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a decrease in work accuracy due to a traveling offset due to a steering angle error. An autonomous traveling system for a work vehicle has a steering angle setting unit 16E for setting a target steering angle θs and a steering angle sensor 18 for detecting the steering angle, and the steering angle setting unit 16E has a target steering angle. It has a steering angle calculating means 16Ea for calculating an angle θs, a steering angle error detecting means 16Eb for detecting a steering angle error, and a steering angle correcting means 16Ec for correcting a target steering angle θs based on a steering angle error. The error detecting means 16Eb is a gaze point setting process for setting a gaze point on a target path with a certain distance from the current position on the traveling direction side during autonomous driving, and a line segment for generating a line segment from the current position to the gaze point. The generation process and the rudder angle error calculation process for calculating the angle formed by the target path P and the line segment as the rudder angle error are performed, and the rudder angle correction means 16Ec targets the rudder angle error obtained by the rudder angle error calculation process. A correction process is performed to add to the steering angle θs. [Selection diagram] Fig. 2

Description

  The present invention relates to an autonomous traveling system for a working vehicle that can be used for a passenger work vehicle such as a tractor, a riding rice transplanter, a combiner, a riding mower, a wheel loader, a snowplow, and an unmanned working vehicle such as an unmanned mower. Specifically, a storage unit that stores a target route generated in advance, a positioning unit that measures the current position and current direction of the host vehicle, and automatic steering of the steered wheels so that the host vehicle autonomously travels on the target route The present invention relates to an autonomous traveling system for a work vehicle including an automatic steering unit.

  In the autonomous traveling system for a working vehicle as described above, a geomagnetic direction sensor that detects the direction of the host vehicle, a GPS receiver that recognizes the current position of the host vehicle, and a rudder angle sensor that detects the steering angle of the front wheels, During the autonomous traveling of the work vehicle on the straight target route, the center position that is the center position between the front wheels on the front side of the vehicle body and the GPS position measurement point that is the antenna installation position of the GPS receiver on the rear side of the vehicle body When the front wheel is steered at an arbitrary steering angle while being laterally separated from the straight target path by the first distance or the second distance, the straight target path from the center part on the front side of the vehicle body A target point is set on a straight target path that is a third distance ahead from the intersection of the perpendicular and the straight target path, and a straight line connecting the center and the target point and a straight line parallel to the straight target path passing through the center Previous target direction Previous target direction = Arctan (first distance / third distance)) is calculated, and the target steering angle (target steering angle = direction + steering angle + target direction) is determined by the vehicle body direction, steering angle, and target direction with respect to the straight target path. Is calculated. In addition, a rear target point is set on the straight target path that is a fourth distance ahead from the intersection of the perpendicular to the straight target path from the GPS position measurement point and the straight target path, and the straight line connecting the GPS position measurement point and the rear target point. And a target azimuth (target azimuth = Arctan (second distance / fourth distance)) between the straight target path passing through the GPS position measurement point and a straight line parallel to the straight target path. Then, from the steering control value based on the target steering angle of the front wheel and the proportional and integral values of PI control based on the target direction of the GPS position measurement point, a front wheel steering command value not including an error of the geomagnetic direction sensor is calculated. The vehicle is configured to autonomously travel along the target route 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 the command value. (See, for example, Patent Document 1).

JP 2002-358122 A

  In the configuration described in Patent Document 1, since the steering angle error due to individual differences of the steering angle sensor is not considered in performing the automatic steering of the front wheels, as shown in FIG. When the vehicle travels autonomously along the straight work path P1 of the target route P, the actual steering angle of the steered wheels goes straight due to the rudder angle error even if the target steer angle of the steered wheels is set to the target steer angle for straight travel Therefore, the work vehicle 1 is gradually offset in an oblique direction from the straight traveling work path portion P1 in accordance with the amount of deviation at this time. Thereafter, even if the target steering angle of the steered wheels is changed to the target steering angle for returning the work vehicle 1 to the straight path P1 based on the offset at this time, the amount of change in the target steering angle at this time is the steering amount. This offsets the angular error, and the work vehicle 1 travels in a state where a certain travel offset amount So is left for the straight traveling work path portion P1. As a result, the work accuracy is reduced due to the travel offset.

  In view of this situation, a main problem of the present invention is to provide an autonomous traveling system for a work vehicle that can suppress a decrease in work accuracy due to a traveling offset caused by a steering angle error.

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

According to this configuration, the rudder angle error detection means can easily detect the rudder angle error during autonomous traveling by performing the above-described gazing point setting process, line segment generation process, and rudder angle error calculation process. it can. Then, the steering angle correction means performs the above-described correction processing, thereby obtaining a target steering angle in consideration of the steering angle error, and automatically steering the steered wheels based on the corrected target steering angle. Thus, it is possible to reduce the travel offset amount with respect to the target route of the vehicle during autonomous travel due to the steering angle error.
As a result, it is possible to suppress a decrease in work accuracy due to a travel offset caused by the steering angle error while reducing a calculation load required for calculating the steering angle error.

The second characteristic configuration of the present invention is:
The rudder angle error detecting means detects a rudder angle error until a predetermined condition for determining whether or not a predetermined condition for allowing detection of the rudder angle error is satisfied, and until the predetermined condition is satisfied. The point is that a detection prohibiting process for prohibiting detection is performed.

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

The third characteristic configuration of the present invention is:
The rudder angle error detecting means determines that the predetermined condition is satisfied when the vehicle travels a certain distance required from the start of autonomous travel to the stabilization of autonomous travel in the detection condition determination processing. It is in.

According to this configuration, the detection of the steering angle error is prohibited by the detection prohibition process until the vehicle travels a certain distance after it starts autonomous driving.
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 when the vehicle starts autonomous driving until the autonomous driving is settled. The target route of the work vehicle during autonomous traveling is caused by the fact that the detection accuracy of the angular error is reduced and the steering wheel is automatically steered based on the target steering angle corrected with the steering angle error having a low detection accuracy. It is possible to avoid the occurrence of inconvenience that the travel offset amount is less likely to decrease.

The fourth characteristic configuration of the present invention is:
The rudder angle error detecting means detects the rudder angle error a plurality of times until the vehicle travels a set distance for rudder angle error detection, and averages the rudder angle error for the plurality of times. A value is obtained and an averaging process is performed in which the average value is used as a steering angle error for the correction process.

  According to this configuration, the steering angle error detection accuracy by the steering angle error detection means can be increased by the averaging process described above. Then, by automatically steering the steered wheels based on the target steering angle corrected with the steering angle error with high detection accuracy, the traveling offset amount with respect to the target route of the vehicle during autonomous traveling is more reliably reduced. be able to. As a result, it is possible to more effectively suppress a decrease in work accuracy due to the travel offset.

The fifth characteristic configuration of the present invention is:
The steering angle error detection means is that the steering angle error is redetected and the steering angle error is updated every time the vehicle travels a set distance for steering angle error redetection 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. And by performing the automatic steering of the steered wheel based on the target steering angle corrected with the steering angle error whose detection accuracy is increased for each update, the longer the autonomous traveling distance of the own vehicle, the longer the autonomous traveling A travel offset amount with respect to the target route of the host vehicle can be reduced, and a reduction in work accuracy due to the travel offset can be more effectively suppressed.

The figure which shows schematic structure of the autonomous running system for work vehicles The block diagram which shows schematic structure of the autonomous running system for work vehicles The figure which shows an example of the target path | route produced | generated in order for the work vehicle to autonomously drive in a farm field Explanatory drawing regarding the calculation of the azimuth deviation when the work vehicle is traveling autonomously on the straight work route section Explanatory drawing about calculation of azimuth angle deviation in the state where work vehicle is autonomously traveling on the backward straight path section Explanatory drawing regarding the calculation of the azimuth deviation when the work vehicle is traveling autonomously on the turning path section Detailed explanatory diagram regarding the calculation of the azimuth deviation in a state where the work vehicle is autonomously traveling along the turning route section Explanatory diagram regarding setting of target point Explanatory drawing which shows the state which the working vehicle carried out the traveling offset with respect to the target route by the steering angle error at the time of autonomous traveling of the working vehicle Explanatory drawing on detection of rudder angle error Flow chart for detection of rudder angle error

An embodiment in which an autonomous traveling system for a work vehicle according to the present invention is applied to a tractor that is 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 is an unmanned operation such as a riding work vehicle other than a tractor, such as a riding rice transplanter, a combiner, a riding mower, a wheel loader, a snowplow, and an unmanned mower. It can be applied to vehicles.

  As shown in FIGS. 1 and 2, the autonomous traveling system for a work vehicle exemplified in the present embodiment includes an autonomous traveling unit 2 mounted on the tractor 1 and a mobile unit configured to communicate with the autonomous traveling unit 2. The communication terminal 3 is provided. As the mobile communication terminal 3, a tablet personal computer or a smartphone having a touch-operable liquid crystal panel 4 or the like can be used.

As shown in FIG. 1, the tractor 1 is connected to a rotary tiller specification by connecting a rotary tiller 6, which is an example of a working device, to a rear portion thereof via a three-point link mechanism 5 so as to be movable up and down and to be able to roll. It is configured.
In addition, it can replace with the rotary tilling apparatus 6 and can connect working apparatuses, such as a plow, a seeding apparatus, and a spraying apparatus, to the rear part of the tractor 1. FIG.

As shown in FIGS. 1 and 2, the tractor 1 has left and right front wheels 7 that function as steerable steering wheels, right and left rear wheels 8 that can be driven, a cabin 9 that forms a riding-type driving unit, and a common rail system. Equipped with an electronically controlled diesel engine (hereinafter referred to as an engine) 10, an electronically controlled transmission 11 for shifting power from the engine 10, an all-hydraulic power steering mechanism 12 for steering left and right front wheels 7, left and right Left and right side brakes (not shown) for braking 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 intermittently transmits power to the rotary tiller 6 ( (Not shown), an electronically controlled clutch operating mechanism 14 that enables hydraulic operation of the work clutch, and an electrohydraulic controlled lifting drive that drives the rotary tiller 6 up and down A mechanism 15, an in-vehicle electronic control unit (hereinafter referred to as an in-vehicle ECU) 16 having various control programs relating to autonomous driving of the host vehicle (tractor) 1, a vehicle speed sensor 17 for detecting the vehicle speed of the host vehicle 1, and the front wheels 7 A steering angle sensor 18 that detects a steering angle, a positioning unit 19 that measures a current position and a current direction of the host vehicle 1, and the like are provided.
The engine 10 may be an electronically controlled gasoline engine equipped with an electronic governor. As the transmission 11, a hydraulic mechanical continuously variable transmission (HMT), a hydrostatic continuously variable transmission (HST), a belt-type continuously variable transmission, or the like can be employed. The power steering mechanism 12 may be an electric power steering mechanism 12 equipped with an electric motor.

  As shown in FIG. 1, the cabin 9 includes a steering wheel 20 and a user seat 21 that enable manual steering of the left and right front wheels 7 via a power steering mechanism 12. Although not shown, a shift lever that enables manual operation of the transmission 11, left and right brake pedals that allow manual operation of the left and right side brakes, and manual lifting operation of the rotary tiller 6 can be performed. A lifting lever is provided.

  As shown in FIG. 2, the in-vehicle ECU 16 includes a transmission control unit 16 </ b> A that controls the operation of the transmission 11, a braking control unit 16 </ b> B 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. Unit 16C, nonvolatile vehicle-mounted storage unit 16D that stores a target route P for autonomous driving generated in advance, and the target steering angle θs of the left and right front wheels 7 during autonomous driving and output to the power steering mechanism 12 And a steering angle setting unit 16E.

  As shown in FIGS. 1 to 3, the positioning unit 19 uses the GPS (Global Positioning System), which is an example of a global navigation satellite system (GNSS), An inertial measurement unit (IMU) that has a satellite navigation device 22 that measures the current azimuth θ1 and a posture, azimuth, and the like of the vehicle 1 having a three-axis gyroscope and a three-direction acceleration sensor ) 23 and the like. Positioning methods using GPS include DGPS (Differential GPS) and RTK-GPS (Real Time Kinematic GPS). In this embodiment, an RTK suitable for positioning of a moving object. -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 can wirelessly communicate various data including positioning data between the GPS antennas 26 and 27 that receive radio waves transmitted from the GPS satellite 25 and the tractor 1 and the reference station 24. Communication modules 28, 29, etc. are provided. Thereby, the satellite navigation device 22 receives the positioning data obtained by the GPS antenna 26 on the tractor side receiving the radio wave from the GPS satellite 25, and the GPS antenna 27 on the base station side receives the radio wave from the GPS satellite 25. Based on the obtained positioning data, the current position p1 and the current direction θ1 of the host vehicle 1 can be measured with high accuracy. In addition, the positioning unit 19 includes the satellite navigation device 22 and the inertial measurement device 23, so that the current position p1, the current azimuth θ1, and the attitude angle (yaw angle, roll angle, pitch angle) of the host vehicle 1 are highly accurate. 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 tractor side. A communication module 31 that enables wireless communication of various data including positioning data with the other communication module 28 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 traveling, and various input data input by the user, a target route P generated by the target route generation unit 30A, and the like. The storage unit 30B is included.

  As shown in FIGS. 1 to 3, the target route generation unit 30 </ b> A follows the input guidance for target route generation displayed on the liquid crystal panel 4, body data such as the type and type of work vehicle and work device, and work When the target field position, etc. 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 body data and the field position. If the corresponding target route P is stored, the target route P is read from the terminal storage unit 30B and displayed on the liquid crystal panel 4. When the corresponding target route P is not stored, the positioning data acquisition travel guidance for obtaining the positioning data necessary for generating the target route P is displayed on the liquid crystal panel 4 and the user performs the positioning data acquisition travel. Make it. Then, based on the positioning data obtained by wireless communication with the tractor 1 during the positioning data acquisition travel, field data such as the section and shape of the work target field is acquired, and the acquired field data and body data Based on the minimum turning radius, work width, and the like included in the target tractor 1, a target route P suitable for working on the field to be worked with the tractor 1 is generated. 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 the vehicle body data and the field data. 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, an agricultural field partitioned into a rectangular shape is illustrated as an agricultural field to be worked. Further, as a target route P suitable for this rectangular field, a plurality of straight work path portions P1 having the same straight travel distance and arranged in parallel at a fixed distance corresponding to the work width and adjacent straight travel A reciprocating travel route including a plurality of direction changing route portions P2 extending from the end point P1e and the start end point P1s of the work route portion P1 to reciprocate the tractor 1 from the start end point Ps of the target route P to the end point Pe is illustrated. ing. Of the plurality of straight-ahead work path portions P1, the odd-numbered rows are the forward paths and the even-numbered rows are the backward paths. The plurality of direction change path parts P2 are a first turning path part P3 that turns the tractor 1 90 degrees from the terminal point P1e of the straight traveling work path part P1 toward the next straight traveling work path part side, and a first turning path part P3. From the turning end point P3e to the previous straight traveling work path part side, the rear straight traveling path part P4 for moving the tractor 1 straight backward, and the rearward straight traveling path part P4 from the rearward finishing point P4e to the next straight working work path part P1. It is divided 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 host vehicle 1.
Note that 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 terminal point P1e of the straight work route portion P1 to the start point of the next straight work route portion P1. You may produce | generate so that the U-turn path | route part which makes the tractor 1 turn 180 degree | times toward the point P1s may be provided.

As shown in FIGS. 2 to 3, when the target ECU P is instructed and displayed on the liquid crystal panel 4, the terminal ECU 30 is instructed to execute autonomous traveling by operating the liquid crystal panel 4 by the user. The target route P being displayed together with the execution command is transmitted to the in-vehicle 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 in-vehicle ECU 16 at a time before the tractor 1 starts autonomous traveling. Further, for example, in a 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 driving, only the initial route portion of the target route P is the terminal ECU 30. After the autonomous traveling is started, every time the tractor 1 reaches a route acquisition point set according to the amount of data, only the subsequent route portion corresponding to that point is transferred from the terminal ECU 30 to the vehicle-mounted ECU 16. You may make it transmit to.

  When the in-vehicle ECU 16 receives the execution command and the target route P of the autonomous traveling from the terminal ECU 30, the in-vehicle ECU 16 stores the received target route P in the in-vehicle storage unit 16D and confirms the data amount. Is started based on the target route P stored in the in-vehicle storage unit 16D.

The autonomous traveling control includes automatic shift control for automatically controlling the operation of the transmission 11, automatic braking control for automatically controlling the operation of the brake operation mechanism 13, automatic steering control for automatically steering the left and right front wheels 7, and a rotary tillage device. The work automatic control for automatically controlling the operation of 6 is included.
In the automatic shift control, the shift control unit 16A determines the travel mode of the tractor 1 on the target path P based on the target path P including the target vehicle speed described above, 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 set target vehicle speed is obtained as the vehicle speed of the host vehicle 1.
In the automatic braking control, the braking control unit 16B properly controls the left and right side brakes on the left and right rear wheels 8 in the braking area included in the target route P based on the target route 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 route P and the output of the positioning unit 19 so that the vehicle 1 autonomously travels on the target route P. The target steering angle θs thus set 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 angle 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 working device control unit 16C rotates based on the target route P and the output of the positioning unit 19 as the host vehicle 1 reaches the start point P1s of the straight work route portion P1. 6 and the clutch operating mechanism 14 and the elevating drive mechanism 15 so that the tilling by the rotary tiller 6 is stopped as the own vehicle 1 reaches the terminal point P1e of the straight traveling work path portion P1. Automatic control of the operation.

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

  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 includes a steering angle calculation unit 16Ea that calculates the target steering angle θs during autonomous traveling. The steering angle calculation means 16Ea performs a target point setting process for setting a target point p2 on a target route having a predetermined distance D1 from the current position p1 of the own vehicle 1 to the traveling direction side during the autonomous traveling, and the current position of the own vehicle 1 A line segment generation process for generating a line segment L1 from the position p1 to the target point p2 and a target steering angle calculation process for calculating an angle formed by the current direction θ1 of the host vehicle 1 and the line segment L1 as the target steering angle θs are performed. .

The target steering angle calculation process will be described in detail. In the target steering angle calculation process, as shown in FIGS. 4 to 5, if the current travel route of the vehicle 1 is the straight work route portion P1 or the backward straight route portion P4. If the direction from the current position p1 of the host vehicle 1 to the target point p2 (the direction of the line segment L1) is the target azimuth angle θ2 and the angle formed by the target route 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 angle θ2 = azimuth angle θp1 of straight traveling work path portion P1 + travel correction angle θc
The target azimuth angle θ2 in the backward straight path part P4 is
Target azimuth angle θ2 = Azimuth angle θp4 of the straight straight path portion P4 + travel correction angle θc
It becomes.
Here, the azimuth angle θp1 of the straight-ahead work path portion P1 and the azimuth angle θp4 of the backward straight-ahead path portion P4 are known at the stage of generating the target route P. 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 angle θp1 = atan2 (V1e, V1n) of the straight traveling work path portion P1
It becomes. 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 angle θp4 = atan2 (V4e, V4n) of the backward straight path portion P4
It becomes. The travel correction angle θc is D1 as the predetermined distance for setting the target point if the lateral deviation from the travel route of the vehicle 1 on the NED coordinates is D2.
Travel correction angle θc = asin (lateral deviation D2 / predetermined distance D1)
Thus, 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 host vehicle 1 measured by the positioning unit 19. Can do.
On the other hand, as shown in FIGS. 6 to 7, if the current travel route of the vehicle 1 is the first turning route portion P3 or the second turning route portion P5, the turning center pt of each of the turning route portions P3, P5. If the angle formed by the vector Vv from the vehicle 1 to the host vehicle 1 and the N-axis is θv, the target steering angle θs is calculated from the angle θv, the current direction θ1 of the host 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.
Here, degrees are used for all units in the formula, and “90” in the formula indicates 90 degrees. Further, regarding “SignTrn”, it is “1” if the turning direction is the clockwise direction, and “−1” if the turning direction is the counterclockwise direction. The travel correction angle θc in the above formula is the predetermined distance D1 for setting the target point, the distance D3 from the turning center pt of the turning path parts P3 and P5 to the host vehicle 1, and the turning of the turning path parts P3 and P5. From radius R,
Traveling 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 parts P3 and P5 to the own vehicle 1 in this equation is calculated by the turning radius R of the turning path parts P3 and P5 and the own vehicle 1 on the NED coordinates. From the lateral deviation D2 from the turning path parts P3, P5,
Distance D3 = turning radius R + lateral deviation D2
Can be obtained.
That is, the calculation load applied to the steering angle calculation means 16Ea in the target steering angle calculation process described above can be reduced.

As shown in FIGS. 4 to 7, the in-vehicle storage unit 16 </ b> D has a plurality of predetermined distances D <b> 1 a to D <b> 1 c for target point setting that are set to different lengths according to the types of the route parts P <b> 1 to P <b> 5 in the target route P. Is remembered. The steering angle calculation means 16Ea automatically changes the predetermined distance D1 for target point setting in the target point setting process according to the type of each of the route portions P1 to P5 on which the host 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.

With respect to the predetermined distance D1 for setting the target point, the steering angle calculation means 16Ea determines the predetermined distance D1 when the current position p1 of the own vehicle 1 is the straight traveling work path portion P1, as shown in FIG. It changes to the 1st predetermined distance D1a suitable for carrying out autonomous driving | running | working by the straight work | work path | route part P1.
As shown in FIG. 5, when the current position p1 of the host vehicle 1 is the backward straight path portion P4, the steering angle calculation means 16Ea travels the predetermined distance D1 and the host vehicle 1 autonomously travels by the rear straight path portion P4. To the second predetermined distance D1b suitable for the above. The second predetermined distance D1b is the rear steering that steers the left and right front wheels 7 on the rear side in the traveling direction when the own vehicle 1 corrects the traveling direction in the autonomous traveling on the backward straight path portion P4. In consideration of an increase in the shake amount, the distance is set to be longer than the first predetermined distance D1a.
When the current position p1 of the host vehicle 1 is the first turning path part P3 or the second turning path part P5, as shown in FIGS. The distance is changed to a third predetermined distance D1c suitable for autonomous traveling on the first turning path part P3 or the second turning path part P5. The third predetermined distance D1c is determined in consideration of the fact that the vehicle 1 is likely to be separated from the turning path portions P3 and P5 in the autonomous traveling in the first turning path portion P3 or the second turning route portion P5. The distance is set shorter than the predetermined distance D1a and the second predetermined distance D1b.

As shown in FIG. 8, the steering angle calculation means 16Ea is configured so that the current position p1 of the host vehicle 1 is different from the current route portion (for example, the straight-ahead work route portion P1) to the next route portion (for example, the first turning route portion P3). The target point p2 is set on the extension line of the current route portion until the switch to (1).
Thus, for example, while the vehicle 1 is autonomously traveling on the straight traveling work path portion P1, it is possible to set a target point p2 suitable for autonomous traveling on the straight traveling work route portion P1, and from this target point p2 It is possible to calculate the target steering angle θs suitable for autonomous traveling on the straight traveling work path portion P1. In addition, while the vehicle 1 is autonomously traveling on the first turning route portion P3, a target point p2 suitable for autonomous traveling on the first turning route portion P3 can be set. It is possible to calculate the target steering angle θs suitable for autonomous traveling on the one turning path portion P3. As a result, the traveling accuracy when the vehicle 1 autonomously travels on the target route P can be improved.

  By the way, as shown in FIG. 9, in the work vehicle such as the tractor 1, the steering system includes the steering angle error θe due to individual differences of the steering angle sensor 18 and the like, so that when the vehicle is traveling autonomously, Due to the angular error θe, the work vehicle travels in a state where a certain travel offset amount So for the target route P remains. As a result, the work accuracy is reduced due to the travel offset.

  Therefore, as shown in FIG. 2, the steering angle setting unit 16E includes a steering angle error detection unit 16Eb that detects a steering angle error θe during autonomous traveling, and a steering angle error θe in addition to the steering angle calculation unit 16Ea. Steering angle correction means 16Ec for correcting the target steering angle θs.

As shown in FIGS. 10 to 11, the steering angle error detecting means 16Eb is a traveling direction side from the current position p1 of the own vehicle 1 when the host vehicle 1 is traveling straight by the autonomous traveling on the straight traveling work path portion P1 of the target route P. A gazing point setting process (step # 3) for setting a gazing point p3 on a target route having a predetermined distance D4 (front side), and a line for generating a line segment L2 extending from the current position of the vehicle 1 to the gazing point p3. A minute generation process (step # 4) and a steering angle error calculation process (step # 5) for calculating the angle formed by the target route P and the line segment L2 as the steering angle error θe are performed. In the rudder angle error calculation process, if the lateral deviation from the straight work path portion P1 of the host vehicle 1 on the NED coordinate is D5, the fixed distance for setting the point of gaze is D4. Angular error θe
Rudder angle error θe = asin (lateral deviation D5 / constant distance D4)
Can be obtained.
The steering angle correction means 16Ec performs a correction process for adding the steering angle error θe obtained by the steering angle error calculation process to the target steering angle θs obtained by the target steering angle calculation process described above.
As a result, the target steering angle θs can be corrected to a value in which the steering angle error θe is taken into account, and the target steering angle θs after this correction processing is output to the power steering mechanism 12, so The travel offset amount So for one target route P can be reduced. As a result, it is possible to suppress a decrease in work accuracy due to the travel offset.

As shown in FIGS. 3 and 10-11, the steering angle error detection means 16Eb detects whether or not a predetermined condition that allows detection of the steering angle error θe is satisfied (step # 1). Until the predetermined condition is satisfied, a detection prohibiting process (step # 2) for prohibiting the detection of the steering angle error θe is performed.
In the present embodiment, as the predetermined condition, it is set whether or not the vehicle 1 has traveled a certain distance La required for the autonomous traveling to settle after the autonomous traveling on the straight traveling work path portion P1 is started. . The steering angle error detection means 16Eb determines that the predetermined condition is satisfied in the detection condition determination process when the vehicle 1 has traveled a certain distance La after starting the autonomous traveling on the straight traveling work route portion P1. In this way, until the self-vehicle 1 starts autonomous traveling on the straight traveling work path portion P1 and runs through a certain distance La, the steering angle error θe is detected by the detection prohibiting process. Detection is prohibited.
As a result, detection of the steering angle error θe and target steering based on the detected steering angle error θe even after the own vehicle 1 starts autonomous traveling on the straight traveling work path portion P1 until the autonomous traveling is settled. By correcting the angle θs, the detection accuracy of the steering angle error θe is lowered, and the target steering angle θs is corrected based on the steering angle error θe having a low detection accuracy and output to the power steering mechanism 12. Due to the above, it is possible to avoid the occurrence of inconvenience that the traveling offset amount So with respect to the target route P of the vehicle 1 during the autonomous traveling is difficult to decrease.

As shown in FIGS. 3 and 11, the rudder angle error detecting means 16Eb determines whether or not the host vehicle 1 has run through the first set distance Lb for rudder angle error detection after running through the fixed distance La. A running discrimination process (step # 6) is performed, and until the host vehicle 1 runs through the first set distance Lb for detecting the steering angle error, the steering angle error θe is detected every set time. Along with running through the first set distance Lb, an average value of a plurality of steering angle errors θe detected every set time is obtained, and this average value is used as a steering angle error θe for correction processing. (Step # 7) is performed.
Thereby, the detection accuracy of the steering angle error θe by the steering angle error detection means 16Eb can be increased. Then, the steering angle correction means 16Ec outputs the target steering angle θs corrected with the highly accurate steering angle error θe to the power steering mechanism 12, so that the traveling offset amount So with respect to the target route P of the host vehicle 1 during autonomous traveling is obtained. Can be reliably reduced. As a result, it is possible to more effectively suppress a decrease in work accuracy due to the travel offset.

The steering angle error detecting means 16Eb determines whether or not the vehicle 1 has traveled the second set distance Lc for redetecting the steering angle error longer than the first set distance Lb (step # 9). ), And every time the host vehicle 1 runs through the second set distance Lc, the average value of the steering angle error θe is redetected based on the above-described processing procedure to update the steering angle error θe.
As a result, the steering angle error detection 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 has an increased accuracy for each update. 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 traveling distance in the straight traveling work path portion P1 of the own vehicle 1 becomes longer, the traveling offset amount So with respect to the target route P of the own vehicle 1 at the time of autonomous traveling can be reduced, and the work accuracy by the traveling offset can be reduced. Reduction can be more effectively suppressed.
The difference between the first set distance Lb for detecting the rudder angle error and the second set distance Lc for detecting the rudder angle error again is based on the steered angle error θe obtained by traveling the first set distance Lb. In autonomous traveling by automatic steering after the correction of the angle θs, the traveling distance until the autonomous traveling is settled is set.

As shown in FIG. 11, the rudder angle error detecting means 16Eb determines whether or not the host vehicle 1 has shifted from the straight-ahead work route portion P1 to the direction change route portion P2 during the execution of the averaging process described above. When the transition determination process (step # 8) is performed and the transition is made, the averaging process at this time is terminated, and an averaging stop process (step # 10) in which the average value of the steering angle error θe is not obtained is performed.
Thereby, in the averaging process of the steering angle error θe, the steering angle error θe at the time of turning having a component different from the steering angle error θe at the time of straight traveling is mixed with the steering angle error θe at the time of straight traveling. It is possible to prevent a decrease in detection accuracy of the angular error θe.

Although illustration is omitted, the rudder angle error detection means 16Eb determines whether the current straight-ahead work path portion P1 is an odd-numbered row or an even-numbered row each time the host vehicle 1 starts autonomous traveling on each straight-headed work route portion P1. If the current straight-ahead work path part P1 is an odd-numbered line (outward part), the steering angle error θe detected during the autonomous traveling in the current straight-ahead work path part P1 is determined as the steering angle error for the forward path. In the update process described above, the forward steering angle error θe is updated every time the forward steering angle error θe is detected. Further, if the current straight-ahead work path portion P1 is an even-numbered line (return path portion), the steering angle error θe detected during autonomous traveling on the current straight-ahead work path portion P1 is set as the steering angle error θe for the return path, and In the update process, the steering angle error θe for the return path is updated every time the steering angle error θe for the return path is detected.
The steering angle correction means 16Ec determines the forward steering angle error θe based on the determination result obtained in the above-described numerical sequence determination processing, if the current straight-ahead work path portion P1 is an odd number sequence, the target steering angle calculation processing described above. The correction process for the forward path is performed to add to the target steering angle θs obtained in the above. Further, if the current straight traveling work path portion P1 is an even-numbered row, a return path correction process for adding the return path steering angle error θe to the target steering angle θs obtained by the target steering angle calculation process described above is performed.
Thereby, 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 along the odd-numbered straight traveling work path portion (outward path portion) P1 and an even number. When there is a difference in the steering angle error θe between the case of autonomous traveling on the straight work path portion (return path portion) P1 in the row, the forward steering angle error θe is updated by the backward steering angle error θe. 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 backward path with the steering angle error θe for the forward path.
Specifically, for example, in an agricultural field in which the direction of the odd-numbered straight line work path part (outward path part) P1 is true north and the direction of the even-numbered straight line work path part (return path part) P1 is true south. When the vehicle 1 is traveling autonomously along an odd-numbered straight-line work path portion (outward-path portion) P1, the direction of the own vehicle 1 measured by the positioning unit 19 is 0 degree, and the own vehicle 1 is an even-numbered row. In the case where the vehicle travels autonomously on the straight traveling work route portion (returning route portion) P1, it is ideal that the orientation of the own vehicle 1 measured by the positioning unit 19 is 180 degrees. Positioning is performed despite the fact that the vehicle 1 is autonomously traveling on the odd-numbered straight traveling route portion (outward portion) P1 due to an error in the yaw angle of the vehicle 1 measured by the vehicle 19 or the like. The direction of the vehicle 1 measured by the unit 19 may be slightly different from 0 degrees. Straight working path portion of the sequence (the return portions) P1 Despite the autonomous, the orientation of the vehicle 1, the positioning unit 19 measures there is a little deviated from 180 degrees.
Thus, originally, the direction of the host vehicle 1 when the host vehicle 1 autonomously travels along the odd-numbered straight-line work path part (outward path part) P1, and the straight-line work path part (return path) of the host vehicle 1 in the even-numbered line. Part) Although the angle difference from the direction of the vehicle 1 when autonomously traveling on P1 should be 180 degrees, there may be a disadvantage that the angle difference does not become 180 degrees due to a positioning error.
However, when the host vehicle 1 is traveling autonomously on the same odd-numbered row or the same even-numbered straight-ahead work path portion P1, the direction of deviation in the direction due to the positioning error tends to be constant. The steering angle error θe for the odd-numbered row (for the forward path) and the steering angle error θe for the even-numbered row (for the backward path) are individually detected and updated individually.
As a result, the steering angle error θe for the forward path and the steering angle error θe for the backward path with high detection accuracy can be obtained.
If the straight traveling work path portion P1 on which the vehicle 1 travels autonomously is the forward path portion, the target steering angle θs at this time can be corrected to a value that takes into account the steering angle error θe for the forward path. By outputting the subsequent target steering angle θs to the power steering mechanism 12, the travel offset amount So with respect to the straight traveling work path portion P1 of the host vehicle 1 during the autonomous traveling in the straight traveling work path portion P1 for the forward path is more preferably reduced. Can be made. Further, if the straight traveling work path portion P1 on which the host vehicle 1 autonomously travels is the 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. By outputting the subsequent target steering angle θs to the power steering mechanism 12, the travel offset amount So for the straight traveling work path portion P1 of the host vehicle 1 during the autonomous traveling in the straight traveling work path portion P1 for the return path is more preferably reduced. Can be made.

The steering angle error detection means 16Eb performs a storing process for storing the latest steering angle error θe in the in-vehicle storage unit 16D every time the steering angle error θe is detected or updated, and the steering angle correction means 16Ec performs the detection prohibiting process described above. Thus, 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 with the steering angle error θe stored in the in-vehicle storage unit 16D.
As a result, even during autonomous traveling where 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 that takes into account the steering angle error θe. In addition, by outputting the target steering angle θs after the correction process to the power steering mechanism 12, the travel offset amount So with respect to the target route P of the host vehicle 1 can be reduced.
Further, as described above, since the in-vehicle storage unit 16D is nonvolatile, even after the power is turned off by the key-off operation of the host vehicle 1, the key-on operation is performed and the autonomous running is started. 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 in-vehicle storage unit 16D, and the travel offset amount So with respect to the target route P of the host vehicle 1 can be reduced. it can.

[Another embodiment]
Another embodiment of the present invention will be described.
Note that the configuration of each embodiment described below is not limited to being applied alone, but may be applied in combination with the configuration of another embodiment.

(1) Various changes can be made to the configuration of the work vehicle.
For example, the work vehicle may be configured in a hybrid specification including the engine 10 and an electric motor for traveling, or may be configured in an electric specification including an electric motor for traveling instead of the engine 10. .
For example, the work vehicle may be configured in a semi-crawler specification that includes left and right crawlers instead of the left and right rear wheels 8.
For example, the work vehicle may be configured to have a rear wheel steering specification in which the left and right rear wheels 8 function as steering wheels.

(2) If the steering angle sensor 18 is configured so that the automatic steering unit 32 causes the steering wheel 20 and the left and right front wheels (steering wheels) 7 to be interlocked by mechanical linkage, the steering angle sensor 18 can adjust the rotational operation direction and the rotational operation amount of the steering wheel 20. Based on this, the steering angle of the front wheel (steering wheel) 7 may be detected.

(3) In the detection condition determination process, the steering angle error detection means 16Eb satisfies a predetermined condition when the vehicle 1 has traveled until a certain time has elapsed from the start of autonomous travel until the autonomous travel is settled. It may be configured that the steering angle error θe is detected based on the determination.

(4) In the detection condition determination process, the steering angle error detection means 16Eb determines that the predetermined condition is satisfied when the host vehicle 1 has traveled a set distance set according to the vehicle speed from the start of autonomous travel. The steering angle error θe may be detected.

(5) In the detection condition determination process, the steering angle error detection unit 16Eb uses the steering angle error θe obtained by the above-described gazing point setting process, line segment generation process, and steering angle error calculation process to detect the steering angle error. It may be configured to detect that the steering angle error θe is detected when it is determined that the predetermined condition is satisfied when the value falls below the set value.

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

(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 rudder angle error detection elapses, and the rudder for the plurality of times. The average value of the angle error θe may be configured as the steering angle error θe for correction processing.

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

(9) The steering angle error detection means 16Eb re-detects the steering angle error θe or the average value of the steering angle error θe every time the set time for steering angle error redetection elapses during autonomous traveling, and the steering angle error You may be comprised so that (theta) e may be updated.

(10) The steering angle error detection means 16Eb re-detects the steering angle error θe or the average value of the steering angle error θe every time the host vehicle 1 travels a set distance set according to the vehicle speed, and the steering angle error You may be comprised so that (theta) e may be updated.

(11) The interval (traveling distance or time, etc.) at which the steering angle error detection means 16Eb redetects the steering angle error θe or the average value of the steering angle error θe and updates the steering angle error θe, such as the mobile communication terminal 3 You may comprise so that a setting can be changed arbitrarily by 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 detection means 16Eb stops detecting the steering angle error θe when the steering angle error θe is being detected and the deviation of the host vehicle 1 with respect to the target route P changes more rapidly than the set value. Thereafter, the detection of the steering angle error θe may be resumed when it is determined that the predetermined condition is satisfied in the detection condition determination process described above. 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 detection means 16Eb individually detects each steering angle error θe according to the traveling mode such as forward, reverse, or turning of the host vehicle 1 during autonomous traveling, and the vehicle-mounted storage unit 16D. You may be comprised so that it may memorize. This configuration is suitable when the steering angle error θe changes according to the traveling mode of the host vehicle 1.

(14) When the steering angle error θe is instructed to be updated by an operation of the mobile communication terminal 3 or the like, the steering angle error detection unit 16Eb redetects the steering angle error θe and updates the steering angle error θe. 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 when the wheel 7 or 8 in the work vehicle 1 is replaced, In the case where a change occurs in the running characteristics 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 a change in the vehicle state that affects the steering angle error θe, such as replacement of the wheels 7 and 8 or a change to the crawler of the left and right rear wheels 8, has been performed on the work vehicle 1. A sensor may be provided, and the steering angle error detection means 16Eb may be configured to automatically update the steering angle error θe when the sensor detects a change in the vehicle state.

DESCRIPTION OF SYMBOLS 1 Own vehicle 7 Steering wheel 16D Memory | storage part 16E Steering angle setting part 16Ea Steering angle calculating means 16Eb Steering angle error detection means 16Ec Steering angle correction means 18 Steering angle sensor 19 Positioning unit 32 Automatic steering unit L2 Line segment La Constant distance Lb Setting distance Lc for detecting steering angle error Setting distance P for detecting steering angle error P Target path p1 Current position p3 Gaze point θ1 Current direction θe Steering angle error θs Target steering angle

Claims (5)

A storage unit that stores a target path generated in advance, a positioning unit that measures the current position and current direction of the host vehicle, and an automatic steering unit that automatically steers steering wheels so that the host vehicle travels autonomously along the target path And
The automatic steering unit includes a steering angle setting unit that sets a target steering angle of the steered wheel, and a rudder angle sensor that detects a steering angle of the steered wheel,
The steering angle setting unit corrects the target steering angle with the steering angle error, steering angle calculation means for calculating the target steering angle, steering angle error detection means for detecting a steering angle error during autonomous traveling, and the steering angle error. Rudder angle correction means,
The rudder angle error detection means includes a gazing point setting process for setting a gazing point on the target route that is spaced a certain distance from the current position in the traveling direction during autonomous traveling, and a line extending from the current position to the gazing point. A line generation process for generating a minute, and a steering angle error calculation process for calculating an angle formed by the target route and the line segment as the steering angle error,
The steering angle correction means performs a correction process for adding the steering angle error obtained by the steering angle error calculation process to the target steering angle.   The rudder angle error detecting means detects a rudder angle error until a predetermined condition for determining whether or not a predetermined condition for allowing detection of the rudder angle error is satisfied, and until the predetermined condition is satisfied. The autonomous traveling system for work vehicles according to claim 1 which performs detection prohibition processing which prohibits detection.   The rudder angle error detection means determines that the predetermined condition is satisfied when the vehicle travels a certain distance required from the start of autonomous travel to the stabilization of autonomous travel in the detection condition determination processing. Item 3. An autonomous traveling system for a work vehicle according to Item 2.   The rudder angle error detecting means detects the rudder angle error a plurality of times until the vehicle travels a set distance for rudder angle error detection, and averages the rudder angle error for the plurality of times. The autonomous traveling system for work vehicles as described in any one of Claims 1-3 which perform the averaging process which calculates | requires a value and makes the said average value into the steering angle error for a correction process.   The rudder angle error detecting means re-detects the rudder angle error and updates the rudder angle error each time the vehicle travels a set distance for redetection of the rudder angle error during autonomous traveling. The autonomous traveling system for work vehicles as described in any one of Claim 4.

Images