Work vehicles

Abstract

To make it possible to reduce cost while making addition of a sensor unnecessary by estimating a tire sinking amount by using a detection signal of an obstruction sensor for detecting an obstruction around a machine body.SOLUTION: A tractor T includes: a travelling machine body 1 supported by a plurality of tires 10 and 11; an obstruction sensor 24 provided to the travelling machine body 1 for detecting the obstruction around the machine body, and a control unit 18 to which the detection signal of the obstruction sensor 24 can be input. The obstruction sensor 24 is arranged while facing the ground surface and capable of measuring a distance to the ground surface. The control unit 18 includes tire sinking amount estimation means for estimating a tire sinking amount D of the tires 10 and 11 on the basis of a distance L from the obstruction sensor 24 to the ground surface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a work vehicle such as a tractor. [Background technology]

[0002] There is known a work vehicle that can perform automatic steering control to automatically control the front wheels based on the position information of the traveling vehicle acquired by a position information acquisition system (see, for example, Patent Document 1). This type of work vehicle is usually equipped with an obstacle sensor that detects obstacles around the vehicle, and has a function to automatically stop the vehicle's traveling or issue an alarm in response to the detection signal from the obstacle sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-23649 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-345805 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in this type of work vehicle, the amount of tire sinking may affect the accuracy of automatic steering control, obstacle detection control, etc. Patent Document 2 discloses a technology for calculating the amount of tire sinking based on the detection signal of an ultrasonic sensor mounted on the bottom of the vehicle, but this requires the addition of an ultrasonic sensor, which increases costs. [Means for solving the problem]

[0005] The present invention has been created in view of the above-mentioned circumstances and with the aim of solving these problems. The invention of claim 1 is a work vehicle comprising a traveling body supported by a plurality of tires, an obstacle sensor provided on the traveling body for detecting obstacles around the body, and a control unit to which a detection signal from the obstacle sensor can be input, wherein the obstacle sensor is arranged facing the ground and is capable of measuring the distance to the ground, and the control unit is provided with tire sinkage amount estimation means for estimating the amount of sinkage of the tire based on the distance from the obstacle sensor to the ground. The control unit is characterized by further comprising an obstacle determination means for determining, based on the detection signal of the obstacle sensor, that a detected object that is equal to or higher than a predetermined determination height is an obstacle, and an obstacle determination height change means for changing the predetermined determination height based on the amount of sinking of the tire. Furthermore, the invention of claim 2 is a work vehicle as described in claim 1, further comprising a position information acquisition system that acquires position information of the traveling body, and the control unit further comprises a plow pan position detection means that detects the position of the plow pan in the field based on the position information of the traveling body and the amount of sinking of the tires. [Effects of the Invention]

[0006] According to the invention of claim 1, the amount of tire sinking is estimated using the detection signal of an obstacle sensor that detects obstacles around the vehicle, which eliminates the need for additional sensors and reduces costs. Furthermore, since the obstacle determination height is changed based on the tire sinking amount, the accuracy of obstacle determination can be improved. Furthermore, according to the invention of claim 2, the position of the tillage pan in the field is detected based on the position information of the traveling machine body and the amount of tire sinking, making it possible to perform work according to the tillage pan position and improving work accuracy. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a side view of a tractor according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. 2 is a perspective view of the rear of the traveling body as viewed from above and rear on the left. [Figure 4] FIG. 2 is a block diagram showing a control configuration of the tractor. [Figure 5] FIG. 2 is an explanatory diagram illustrating the principle of estimating the amount of tire sinkage. [Figure 6] 1A is an explanatory diagram showing the principle of correction of the tire sinking amount according to the aircraft attitude, and FIG. 1B is an explanatory diagram showing the principle of correction of the obstacle determination height. [Figure 7] 10 is a flowchart showing a procedure for tire sinkage amount estimation control. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Figures 1 to 3, T is a tractor (work vehicle), and the tractor T includes a traveling body 1 and a work implement 3 connected to the rear of the traveling body 1 via a lifting link mechanism 2.

[0009] The lifting link mechanism 2 is, for example, a three-point link mechanism, and includes a top link 4, a pair of left and right lower links 5, a pair of left and right lift arms (not shown) that suspend the lower links 5 via a pair of left and right lift rods 6, and a lift cylinder (not shown) that raises and lowers the pair of left and right lift arms.

[0010] The work machine 3 of this embodiment is a rotary tillage work machine that is connected to the rear of the traveling body 1 and tills the soil, and is equipped with tillage tines 7 that are rotated and driven by working power supplied from the traveling body 1, a rotary cover 8 that covers the top of the tillage tines 7, and a rear cover 9 that is connected to the rear end of the rotary cover 8 so that it can swing up and down and levels the tilled soil that has been tilled by the tillage tines 7.

[0011] The traveling machine body 1 is supported by a plurality of tires 10, 11. The plurality of tires 10, 11 includes a pair of left and right front wheel tires 10 that are steered by a steering handle 12 and driven to rotate by engine power, and a pair of left and right rear wheel tires 11 that are also driven to rotate by engine power.

[0012] The running body 1 of this embodiment comprises an engine mounting section E on which an engine (not shown) is mounted, a transmission case 13 that changes the speed of the engine power and supplies it to the front wheel tires 10, the rear wheel tires 11 and the work equipment 3, a control section 14 on which an operator can ride, and a cabin 15 that covers the control section 14.

[0013] In addition, the running body 1 is capable of performing automatic steering control to cause the running body 1 to travel automatically, and as shown in Figures 1 to 4, the configuration for performing automatic steering control includes a position information acquisition system 16 that acquires position information of the running body 1, an automatic steering unit 17 that steers the front wheel tires 10 of the running body 1 by driving an actuator, and a control unit 18 that controls the automatic steering unit 17 based on the position information of the running body 1 acquired by the position information acquisition system 16.

[0014] The position information acquisition system 16 may be, for example, an RTK-GNSS positioning system capable of highly accurate positioning with an error of a few centimeters. The RTK-GNSS positioning system performs GNSS positioning such as GPS at both a fixed base station and a moving mobile station, and corrects the positioning data in real time using a correction signal transmitted from the base station to the mobile station, thereby achieving highly accurate positioning with an error of a few centimeters. Furthermore, by installing two GNSS antennas at the mobile station at a predetermined distance, it becomes possible to detect not only the absolute position of the mobile station but also the direction of travel (azimuth) of the mobile station with high accuracy based on the two positioning results.

[0015] Specifically, the position information acquisition system 16 of this embodiment includes a positioning frame 19 provided along the vehicle width direction at the rear end of the roof of the cabin 15, a reference GNSS antenna 20 and a direction GNSS antenna 21 attached to the positioning frame 19 at a predetermined interval in the vehicle width direction, a correction signal receiving device 22 that receives a correction signal from a fixedly installed RTK base station (not shown), and a GNSS unit 23 that is a control unit that performs RTK-GNSS positioning. The GNSS unit 23 transmits positioning data (absolute position data and heading direction data) obtained by RTK-GNSS positioning to the control unit 18 via wired communication means such as a CAN.

[0016] Furthermore, the traveling machine body 1 is equipped with an obstacle sensor 24 that detects obstacles around the machine body. The control unit 18 receives a detection signal from the obstacle sensor 24 and performs emergency stop processing during automatic steering control, obstacle notification processing, obstacle warning processing, and the like.

[0017] The traveling machine body 1 of this embodiment is equipped with a machine body front obstacle sensor (not shown) that detects obstacles in front of the machine body, a machine body side obstacle sensor (not shown) that detects obstacles on the sides of the machine body, and a machine body rear obstacle sensor 24 that detects obstacles behind the machine body. The machine body rear obstacle sensor 24 will be described below, but the obstacle sensor 24 of the present invention is not limited to the machine body rear obstacle sensor 24 and may be a machine body front obstacle sensor or a machine body side obstacle sensor.

[0018] The obstacle sensor 24 is disposed facing the ground and is configured to be able to measure the distance to the ground. For example, it is configured using a laser distance measuring sensor that emits a laser beam toward the ground and can measure the distance to the ground or an obstacle based on the reflected light. The control unit 18 detects the distance to the ground or the height of the obstacle based on the distance measured by the obstacle sensor 24, and determines that an obstacle is present within the detection range of the obstacle sensor 24 if the height of the obstacle is equal to or greater than a predetermined judgment height.

[0019] The obstacle sensor 24 for the rear of the machine body is provided facing rearward and downward in the middle of the positioning frame 19 in the vehicle width direction, and measures the distance to the ground behind the work implement 3. In other words, while the work implement 3 is performing tilling work, the sensor measures the distance to the ground that has been tilled and leveled by the work implement 3, thereby reducing measurement errors due to unevenness in the ground.

[0020] As shown in Figure 4, in addition to the obstacle sensor 24 and GNSS unit 23 mentioned above, the input side of the control unit 18 is connected to a vehicle speed sensor 25 that detects the vehicle speed of the traveling body 1, an IMU 26 (inertial measurement unit, body attitude detection means) that detects the attitude (forward / backward tilt, left / right tilt, etc.) of the traveling body 1, and a lift arm sensor 27 that detects the lift height of the work machine 3, while the output side of the control unit 18 is connected to the automatic steering unit 17 mentioned above, a lift arm valve 28 that switches the hydraulic operation of the lift arm, an engine rotation output 29 that outputs an engine rotation speed instruction to the engine ECU (not shown), and a vehicle speed change output 30 that outputs a vehicle speed change instruction to the traveling transmission (not shown).

[0021] The control unit 18 has functional configurations realized by the cooperation of hardware and software, including a tire subsidence amount estimation means, an automatic steering control means, a gain correction means, an obstacle determination means, an obstacle determination height change means, and a tillage pan position detection means.

[0022] 5, the tire sinking amount estimation means estimates the sinking amount D of the tires 10, 11 based on the distance L from the obstacle sensor 24 to the ground measured by the obstacle sensor 24. For example, if the mounting angle of the obstacle sensor 24 (e.g., the laser light emission angle) is θ1 when based on the aircraft height direction and θ2 (θ2=90°-θ1) when based on the aircraft length direction, and the mounting height of the obstacle sensor 24 when the sinking amount D of the tires 10, 11 is 0 is H, then the sinking amount D of the tires 10, 11 can be calculated by the following formula: D=H-(L×cosθ1) D=H-(L×sinθ2)

[0023] Furthermore, the tire sinking amount estimation means corrects the sinking amount D of the tires 10, 11 based on the attitude of the traveling vehicle body 1 detected by the IMU 26. For example, as shown in Fig. 6(a), when the traveling vehicle body 1 tilts forward, even if the tire sinking amount D of the rear tire 11 does not change, the measured distance L' of the obstacle sensor 24 becomes longer than the measured distance L when the vehicle body is horizontal, and therefore the estimated sinking amount D may be smaller than the actual sinking amount.

[0024] For example, when the tire subsidence amount estimation means uses the subsidence amount of the rear wheel tire 11 as a reference, it makes a correction to increase the subsidence amount D according to the forward tilt angle of the running body 1 and to decrease the subsidence amount D according to the backward tilt angle of the running body 1.

[0025] The automatic steering control means controls the automatic steering unit 17 based on the position information of the traveling vehicle 1 acquired by the position information acquisition system 16. In addition, the gain correction means corrects the gain G of the automatic steering control means based on the subsidence amount D of the tires 10, 11. For example, if the subsidence amount D of the tires 10, 11 is large, the steering load on the front tire 10 becomes large, so the gain G of the automatic steering control means is corrected according to the subsidence amount D using the following formula, where k is a preset coefficient. G=k×D

[0026] The obstacle determination means determines a detected object that is equal to or greater than a predetermined determination height h as an obstacle S based on the detection signal from the obstacle sensor 24. The obstacle determination height change means changes the predetermined determination height h based on the subsidence amount D of the tires 10, 11. For example, as shown in FIG. 6(b), the height at which the obstacle S is detected by the obstacle sensor 24 changes depending on whether the subsidence amount D of the tires 10, 11 is small or large, even if the obstacle S is the same. Therefore, the following formula is used to correct the determination height h of the obstacle S according to the subsidence amount D, where H is the initial determination height (set when the subsidence amount D=0). h=H+D

[0027] The tillage pan position detection means detects the position of the tillage pan in the field based on the position information of the traveling body 1 and the subsidence amount D of the tires 10, 11. For example, it is assumed that the subsidence amount D of the tires 10, 11 approximately matches the depth of the tillage pan (plowing depth), and the subsidence amount D is linked to the position information of the traveling body 1 and stored.

[0028] Next, a specific processing procedure of the tire sinking amount estimation means (tire sinking amount estimation control) will be described with reference to FIG.

[0029] As shown in Fig. 7, the control unit 18 determines whether tilling is in progress (the work implement 3 is in the lowered position) based on the detection value of the lift arm sensor 27 (S1). If the result of this determination is NO, the control unit 18 sets the working distance and the measurement flag to 0 (S2, S3) and returns to the upper routine. If the result of this determination is YES, the control unit 18 determines whether the measurement flag is set (=1) (S4). If the control unit 18 determines that the measurement flag is not set, it starts counting the working distance (S5) and then sets the measurement flag to 1 (S6). If the control unit 18 determines that the measurement flag is set, it increments the working distance count (S7). Next, the control unit 18 determines whether the counted working distance exceeds a predetermined distance A1 (S8). If the result of this determination is YES, the control unit 18 performs ground measurement (processing to estimate the subsidence amount D using the obstacle sensor value) (S9). According to this type of tire subsidence amount estimation control, the subsidence amount D of the tires 10, 11 is estimated after the working distance exceeds a predetermined distance A1, making it possible to estimate the subsidence amount D based on the distance L to the cultivated ground, thereby suppressing measurement errors due to unevenness of the ground, etc.

[0030] According to this embodiment configured as described above, the tractor T comprises a traveling body 1 supported by a plurality of tires 10, 11, an obstacle sensor 24 provided on the traveling body 1 for detecting obstacles around the body, and a control unit 18 to which the detection signal of the obstacle sensor 24 can be input, wherein the obstacle sensor 24 is arranged facing the ground and is capable of measuring the distance to the ground, and the control unit 18 comprises a tire subsidence amount estimation means for estimating the amount of subsidence D of the tires 10, 11 based on the distance L from the obstacle sensor 24 to the ground, thereby eliminating the need for additional sensors and reducing costs.

[0031] In addition, the tractor T is further equipped with a work implement 3 connected to the rear of the running body 1 and for tilling the soil, and the obstacle sensor 24 is capable of measuring the distance L to the ground behind the work implement, and the tire subsidence amount estimation means estimates the amount of subsidence D of the tires 10, 11 based on the distance L from the obstacle sensor 24 to the ground during plowing work by the work implement 3, thereby suppressing measurement errors due to unevenness of the ground, etc., and improving the accuracy of estimating the amount of tire subsidence.

[0032] In addition, the tractor T is further equipped with an IMU 26 that detects the attitude of the running body 1, and the tire subsidence amount estimation means corrects the subsidence amount D of the tires 10, 11 based on the attitude of the running body 1, thereby further improving the estimation accuracy of the tire subsidence amount D.

[0033] In addition, the tractor T further comprises a position information acquisition system 16 that acquires position information of the running body 1, and an automatic steering unit 17 that steers the front wheel tires 10 of the running body 1 by driving an actuator, and the control unit 18 further comprises an automatic steering control means that controls the automatic steering unit 17 based on the position information of the running body 1 acquired by the position information acquisition system 16, and a gain correction means that corrects the gain of the automatic steering control means based on the subsidence amount D of the tires 10, 11, so that the gain of the automatic steering control can be optimized and the control accuracy of the automatic steering control can be improved.

[0034] In addition, the control unit 18 further includes an obstacle determination means for determining, based on the detection signal from the obstacle sensor 24, a detected object that is equal to or greater than a predetermined determination height h as an obstacle S, and an obstacle determination height change means for changing the predetermined determination height h based on the amount of sinking D of the tires 10, 11, thereby improving the accuracy of determining the obstacle S.

[0035] In addition, the control unit 18 further includes a plow pan position detection means for detecting the position of the plow pan in the field based on the position information of the running body 1 and the subsidence amount D of the tires 10, 11. Therefore, by moving the soil or destroying the plow pan based on the map information of the plow pan position, soil improvement and yield improvement can be performed, thereby improving workability. [Explanation of symbols]

[0036] T Tractor 1 Running body 3 Work equipment 10 Front tire 11 Rear tire 16 Location Information Acquisition System 17 Autopilot Unit 18 Control Unit 24 Obstacle Sensor 26 IMU

Claims

1. a traveling machine body supported by a plurality of tires; An obstacle sensor provided on the traveling machine body to detect obstacles around the machine body; a control unit to which a detection signal from the obstacle sensor can be input, the obstacle sensor is arranged facing the ground and is capable of measuring a distance to the ground; the control unit includes a tire sinking amount estimation means for estimating a tire sinking amount based on a distance from the obstacle sensor to the ground, The control unit an obstacle determination means for determining, based on the detection signal from the obstacle sensor, that a detected object having a predetermined determination height or higher is an obstacle; The work vehicle further comprises an obstacle judgment height changing means for changing the predetermined judgment height based on the amount of sinking of the tire.

2. Further comprising a position information acquisition system for acquiring position information of the traveling machine body, 2. The work vehicle according to claim 1, wherein the control unit further comprises a plow position detection means for detecting the position of the plow in the field based on the position information of the traveling machine body and the amount of sinking of the tires.

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