Work vehicle, traveling method of work vehicle, and traveling program of work vehicle

Abstract

To provide a work vehicle capable of performing travel control while avoiding the contact of a caster wheel with a ridge, with a simple constitution.SOLUTION: A work vehicle A includes: travel parts 21 provided on left and right sides of the lower part of a vehicle body 11; a plurality of sensors arranged at an interval at the front, rear, right and left of the vehicle body 11, on the lower part of the vehicle body 11, which can measure the distance from a ridge B; and a controller for performing control to make the travel parts travel along the ridge on the basis of measured values of the sensors. The controller generates a correction speed by correcting a set speed that is arbitrarily set, and controls the travel parts 21 by calculating a swing restriction angular velocity, which is the threshold at which the travel parts 21 can turn around without touching the ridge B, on the basis of the correction speed and a turning radius.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a work vehicle, a work vehicle travel method, and a work vehicle travel program. More specifically, it relates to a work vehicle, a work vehicle travel method, and a work vehicle travel program that can travel along an object regardless of the direction of travel. Even more specifically, it relates to a work vehicle, a work vehicle travel method, and a work vehicle travel program that can control travel while avoiding contact of caster wheels with ridges. [Background technology]

[0002] If travel control along the row direction of the ridges is to be performed by image processing based on image data without using a distance sensor, the system would be very complex. Therefore, travel control using distance sensors is considered. For example, the following document discloses an invention that uses sensors to control travel along the row direction of ridges. The invention described in Patent Document 1, "Travel Position Recognition System, Agricultural Vehicle, and Unmanned Autonomous Traveling Work Vehicle," enables travel along ridges by using left and right sensing plates placed inside the vehicle body that is positioned to straddle the ridges, and distance sensors placed on the left and right ends of the front of the vehicle body. The invention described in Patent Document 2, "Agricultural Work Vehicle, Control Device, and Program," generates acquired point cloud data in three-dimensional space using point cloud data obtained by laser irradiation using a laser light irradiation device mounted on the vehicle. This acquired point cloud data is used to identify the direction of the ridges and make the vehicle travel along the ridges. Furthermore, by replacing the laser light irradiation device with a stereo camera (compound eye camera), it is possible to create distance data and acquire point cloud data. Furthermore, Patent Document 3 discloses the configuration of a running unit of a vehicle that travels across ridges. According to Patent Document 3, the vehicle is provided with drive wheels on the left and right sides of the front, and caster wheels on the left and right sides of the rear. The caster wheels are rotatable around a vertical axis. This configuration is said to prevent damage to the ridges caused by the running unit climbing over them, as opposed to running units that use a crawler system, even when the furrows are narrow or curved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-62816 A [Patent Document 2] Japanese Patent Publication No. 2021-153466 [Patent Document 3] Japanese Utility Model Application Publication No. 6-34406 Summary of the Invention [Problem to be solved by the invention]

[0004] The invention of Patent Document 1 has a problem in that when the robot travels along a ridge using the distance sensor, if a portion of the ridge collapses or there are irregularities in the ridge to be detected, the robot frequently moves left and right repeatedly. Furthermore, while it is sufficient if the plants growing on the ridge can withstand the pressure of the left and right sensing plates, this is not always the case, and there are also cases where there are no plants growing on the ridge. In such cases, the robot travels using only the distance sensor, and the above-mentioned problem becomes more pronounced. Furthermore, because the distance sensor is located at the front of the robot, the robot can only move forward toward the side where the distance sensor is attached. Therefore, when moving backward, there is also the problem that the condition of the ridge detected by the distance sensor cannot be reflected in the robot's travel.

[0005] The invention in Patent Document 2 generates point cloud data by calculation from acquired distance data. This calculation and generation process requires high processing power from the control device and arithmetic device, and the faster the moving speed, the more advanced the processing power becomes. If the control device and arithmetic device are capable of high-speed processing, these devices will be expensive, which will in turn be reflected in the price of the aircraft incorporating them. Therefore, consumers will need a high level of financial means to purchase them.

[0006] According to the disclosure of Patent Document 3, the drive wheels and caster wheels roll along the lowest part of the furrows while traveling, so even if the furrows are curved, they do not climb up too far onto the furrows. However, when using automatic travel control technology to travel along the furrows, advanced technology is required to ensure accurate travel along the lowest part of the furrows. On the other hand, simplifying the control can result in a significant deviation in the positional relationship between the furrows and the vehicle. In this case, it may be necessary to adjust the rotation speed of the drive wheels and increase the vehicle's turning angle, but as mentioned above, it is necessary to avoid contact with the furrows and protect the crops growing in the furrows.

[0007] The present invention has been made in light of the above-mentioned problems, and aims to provide a work vehicle that can travel along an object regardless of the direction of travel while simplifying the control and control device, and that can control travel while avoiding contact of the caster wheels with ridges using a simple configuration. [Means for solving the problem]

[0008] This invention is The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A work vehicle characterized by: relates to.

[0009] The present invention further provides: When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation. A work vehicle characterized by: relates to.

[0010] This invention is The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A method for traveling a work vehicle, relates to.

[0011] The present invention further provides: When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation. A method for traveling a work vehicle, relates to.

[0012] This invention is The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A work vehicle travel program characterized by: relates to.

[0013] The present invention further provides: When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation. A work vehicle travel program characterized by: relates to. [Effects of the Invention]

[0014] The present invention has been made in light of the above-mentioned problems, and provides a work vehicle that can travel along an object regardless of the direction of travel while simplifying the control and control device, and that can control travel while avoiding contact of the caster wheels with ridges with a simple configuration. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a side view of a work vehicle according to a first embodiment of the present invention, with the front side in the traveling direction being the left side in the drawing. [Figure 2] 1 is a plan view of a work vehicle according to a first embodiment of the present invention. [Figure 3] 1 is a front view of a work vehicle according to a first embodiment of the present invention. [Figure 4] 1 is a rear view of a work vehicle according to a first embodiment of the present invention. [Figure 5]1 is a block diagram of a work vehicle according to a first embodiment of the present invention. [Figure 6] FIG. 2 is a block diagram showing details of a control amount calculation unit according to the first embodiment of the present invention. [Figure 7] FIG. 2 is an explanatory diagram showing a schematic diagram of the positional relationship between the work vehicle and ridges, for explaining the control process of the work vehicle according to the first embodiment of the present invention. [Figure 8] 2 is a diagram showing a control process in the control device for the work vehicle according to the first embodiment of the present invention. FIG. [Figure 9] FIG. 3 is a diagram showing a calculation process in a control amount calculation unit according to the first embodiment of the present invention. [Figure 10] 3 is a diagram showing a calculation process performed by a vehicle body motion calculation unit of the control device for a work vehicle according to the first embodiment of the present invention. FIG. [Figure 11] FIG. 3 is a diagram showing the calculation process performed by the temporary ridge data generation unit of the control device for the work vehicle according to the first embodiment of the present invention. [Figure 12] 3 is a diagram showing a calculation process performed by a sensor coordinate correction unit of the control device for the work vehicle according to the first embodiment of the present invention. FIG. [Figure 13] 3 is a diagram showing distance data measured by a sensor of the work vehicle according to the first embodiment of the present invention and corrected distance data after calculation. FIG. [Figure 14] 1 is a conceptual diagram of an operation in a motion model of a work vehicle with two opposing wheels according to a first embodiment of the present invention. FIG. [Figure 15] 3 is a diagram showing an ideal sensor positional relationship (square shape) in a motion model of an opposing two-wheel vehicle of a work vehicle according to a first embodiment of the present invention. FIG. [Figure 16] 3 is a diagram (parallelogram shape) showing the actual sensor positional relationship in a motion model of an opposing two-wheel vehicle of a work vehicle according to a first embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] The outline of the aircraft will be explained based on the drawings. 1 to 14 and 16 are diagrams showing Example 1. Fig. 15 is a diagram showing the ideal sensor positional relationship (square shape) in Example 1. A is a work vehicle. B is a ridge, and B1 is the ridge bottom, which is the bottom position of ridge B. Work vehicle A places body 11 on ridge B, and running unit 21, located below body 11, is placed on ridge bottom B1, sandwiching ridge B, allowing it to run across ridge B. Multiple sensors capable of measuring distance (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4) are placed on body 11, and the distance between the sensors and the ridge B that it is straddling is measured. A control device 31 installed on the vehicle body 11 controls the traveling unit 21 so that it moves along the ridges B in parallel therewith by performing calculations based on the distance data S obtained from the sensor. As shown in the block diagram of FIG. 5, the work vehicle A may also have an operating unit for operating the work vehicle A and a notification unit for issuing notifications.

[0017] The vehicle body 11 and the motor 221 will now be described. As shown in Figures 1 to 4, the car body 11 is configured in a ladder shape made up of multiple long members. A control device 31 (not shown in Figures 1 to 4), a motor 221 that drives the traveling unit 21, and a battery (not shown) that serves as a power source for these are arranged on the car body 11. The motors 221 are arranged on the left and right sides of the car body 11 on the forward side in the forward direction. In this embodiment, the motors 221 are electric motors, and the description will be given assuming that a three-phase AC induction motor is used. In the following description, the motor 221 disposed on the left side relative to the forward direction may be referred to as the left motor 221L or the first motor 221L, and the motor 221 disposed on the right side relative to the forward direction may be referred to as the right motor 221R or the second motor 221R. Also, the motors may be simply referred to as the motors 221 without distinction between left and right.

[0018] The work vehicle A comprises a vehicle body 11 and running sections 21 disposed on the left and right sides of the lower part of the vehicle body 11. The running unit 21 is provided with wheels consisting of drive wheels 22 and driven wheels 23 arranged at the front and rear. The running unit 21 is composed of a pair of front and rear drive wheels 22 and driven wheels 23, and is disposed at the left and right end portions of the vehicle body 11. In one set of running units 21, the drive wheels 22 are disposed on the front side in the traveling direction of the vehicle body 11, and the driven wheels 23 are disposed on the rear side. The drive wheels 22 are perpendicular to the fore-and-aft direction of the vehicle body and are rotatable on left and right axes in the horizontal direction. The drive wheels 22 are rotationally driven by transmission of rotational power from motors 221 disposed on the left and right sides of the vehicle body 11 via speed reducers 222. As shown in the block diagram of Figure 5, the rotation speed of motor 221 is determined via an inverter, which is a travel control unit 316 controlled by control device 31, and the rotation speed can be freely changed by controlling the input frequency to motor 221. Driven wheel 23 is rotatable about horizontal rotation shaft 232. Furthermore, driven wheel 23 can change the rolling direction with respect to the traveling surface by vertical shaft 231.

[0019] Therefore, the vehicle body 11 can move forward or backward by the rotational drive of the drive wheels 22 arranged on the left and right sides at the front of the vehicle body 11, and can also turn by the difference in rotation between the left and right drive wheels 22. In addition, the driven wheels 23 rotate about horizontal rotation axes 232 to follow the drive wheels 22, and rotate about vertical axes 231 in response to the turning motion of the vehicle body 11, so that the vehicle body 11 can move forward and turn stably. 1 to 12, the running unit 21 is configured with drive wheels 22 and driven wheels 23, and the drive wheels 22 are disposed on the front side and the driven wheels 23 are disposed on the rear side. However, this is not limited to this. The drive wheels 22 may be disposed on the rear side and the driven wheels 23 may be disposed on the front side.

[0020] It may also be a crawler-type running unit 21 made up of a drive sprocket, wheels, and crawlers. The drive wheels 22 refer to the wheels located at the extreme end of either the front or rear of the wheels involved in the ground contact of the crawler, and the driven wheels 23 refer to the wheels located at the extreme end of either the front or rear of the wheels involved in the ground contact of the crawler.

[0021] The sensors (first sensor Se1 to fourth sensor Se4) will be described. 1 to 4 and 7, a plurality of sensors (first sensor Se1 to fourth sensor Se4) are arranged at intervals on the lower part of the vehicle body 11 at positions on the front, rear, left and right sides of the vehicle body 11. The sensors (first sensor Se1 to fourth sensor Se4) are capable of measuring the distance to the ridge B. In the first embodiment shown in Figures 1 to 4, ridge B is positioned between the driving wheels 22 and between the driven wheels 23, and sensors (first sensor Se1 to fourth sensor Se4) are directed toward ridge B to perform measurements.

[0022] The ridges B located on the outer side of the driving wheels 22 or the driven wheels 23 of the vehicle body 11 may be measured by directing the sensors (first sensor Se1 to fourth sensor Se4) toward the ridges B. In addition, the multiple sensors arranged in the first embodiment are configured as a first sensor Se1, a second sensor Se2, a third sensor Se3, and a fourth sensor Se4. In the description, the first sensor Se1, the second sensor Se2, the third sensor Se3, and the fourth sensor Se4 may be collectively referred to as sensors or the first sensor Se1 to the fourth sensor Se4.

[0023] The sensors in the first embodiment (first sensor Se1 to fourth sensor Se4) are non-contact distance sensors, and ultrasonic sensors are used. Ultrasonic sensors are sensors that can detect the distance to an object by emitting ultrasonic waves toward the object and receiving the reflected waves. Ultrasonic sensors are also used because they can be installed more cheaply than other types that can achieve the same performance. In addition to the type of sensors used in the embodiment (first sensor Se1 to fourth sensor Se4), it is also possible to use sensors that measure distance using wavelengths such as optical sensors including laser light, electromagnetic waves, etc. Also, a system that determines the distance to an object by capturing an image is also acceptable. Furthermore, a system that measures distance by directly contacting the ridge B is also acceptable. In other words, the sensor may be of a type that can measure the distance to an object. As long as the cost issue is resolved, the measurement system is not important.

[0024] The sensors (first sensor Se1 to fourth sensor Se4) are arranged between the front and rear wheels (drive wheels 22 and driven wheels 23) as shown in FIGS. 1 and 2. More specifically, as shown in FIGS. 1 to 4, the sensors are arranged so as to be located between the drive wheels 22 and driven wheels 23. In this embodiment of the present invention, the first sensor Se1 is arranged behind the left drive wheel 22 arranged on the left side in the direction of travel under the vehicle body 11, and the second sensor Se2 is arranged behind the right drive wheel 22 arranged on the right side in the direction of travel. The third sensor Se3 is arranged behind the first sensor Se1 and in front of the left driven wheel 23 arranged on the left side in the direction of travel, and the fourth sensor Se4 is arranged behind the second sensor Se2 and in front of the right driven wheel 23 arranged on the right side in the direction of travel.

[0025] In other words, the first sensor Se1 to the fourth sensor Se4 are located inside in the front-rear direction of the contact points where the lower ends of the wheels (drive wheels 22 and driven wheels 23) contact the front and rear of the traveling surface. It can also be said that the sensors (first sensor Se1 to fourth sensor Se4) are positioned inside the ground contact distance, which is the distance between the ground contact points at the front and rear of the running part 21 in a side view, and that the sensors (first sensor Se1 to fourth sensor Se4) are positioned inside the ground contact points at the front and rear of the wheels in a plan view. At least a part of the sensors (first sensor Se1 to fourth sensor Se4) in the first embodiment is disposed within the projected area of ​​the travel section 21 when viewed from the traveling direction of the vehicle body 11. Moreover, the sensors (first sensor Se1 to fourth sensor Se4) are arranged within the width of the traveling section 21 when viewed from the traveling direction of the vehicle body 11.

[0026] 1 to 4, in the first embodiment, the detection directions of the sensors (first sensor Se1 to fourth sensor Se4) are directed toward the center of the width of the vehicle body 11 in a plan view. The detection directions of the sensors (first sensor Se1 to fourth sensor Se4) are directed toward the outside of the width of the vehicle body 11 in a plan view. The tips of these sensors may be directed toward the sides of the ridge B so that the distance to the ridge can be measured. Furthermore, the first sensor Se1 to the fourth sensor Se4 are disposed close to the drive wheels 22 and the driven wheels 23. By disposing the sensors in this manner, the first sensor Se1 to the fourth sensor Se4 do not protrude from the front and rear ends of the set of traveling parts 21 in the front-rear direction, so even if there is an obstacle such as a large step in the traveling direction of the traveling part 21, damage to the sensors due to a collision with the obstacle can be avoided.

[0027] As shown in Figures 3 and 4, each of the first sensor Se1 to the fourth sensor Se4 is arranged so that at least a part or all of it overlaps with a wheel (at least one of the drive wheel 22 or the driven wheel 23) in a front view and a rear view seen from the direction of travel. More preferably, it is desirable that most of the width of the sensor is located inside the width of the widest wheel in a front view and a rear view. In the embodiment, the sensor is arranged so that it fits within the width of the drive wheel 22. Furthermore, with respect to the vertical position, the sensor is located above the drive wheel 22. In this case, the upper parts of the first sensor Se1 to the fourth sensor Se4 may protrude upward from the upper end of the drive wheel 22.

[0028] In this way, the first sensor Se1 to the fourth sensor Se4 are arranged inside the width of the widest wheel (at least one of the drive wheels 22 or the driven wheels 23), so the sensors do not protrude to the sides of the set of running parts 21, and contact with the sensors can be avoided even if ridges B, obstacles, etc. approach the sides of the running parts 21. Furthermore, because the first sensor Se1 to the fourth sensor Se4 are located below the vehicle body 11 and above the running parts 21, an appropriate distance from the measurement target is maintained to improve measurement accuracy, and at the same time, a gap can be secured between the first sensor Se1 to the fourth sensor Se4 and the top of the undulations on the running surface even when driving over undulations on the running surface.

[0029] To give a specific example using the embodiment, as shown in Figures 3 and 4, when the traveling unit 21 is positioned to straddle the ridge B and travels along the ridge B, the sensor does not come into contact with the ridge B, which is located below the vehicle body 11 and to the side of the traveling unit 21. Furthermore, when moving within a field or between fields before or after working on the ridge B, even if the vehicle travels across the undulations of the ridge B or ridges, etc., a sufficient gap can be secured between the bottom of the sensor and the undulations, so the vehicle can travel without worrying about damaging the sensor.

[0030] The configuration of the control device 31 will be described. The work vehicle A is equipped with a control device 31 as shown in the block diagram of FIG. The control device 31 controls the traveling section 21 to travel along the ridge B based on the measured values ​​of the sensors (first sensor Se1 to fourth sensor Se4). 5, the control device 31 is composed of a distance data acquisition unit 311, a temporary ridge data generation unit 312, a sensor coordinate correction unit 313, a ridge data generation unit 314, a control amount calculation unit 315, a travel control unit 316, a rotation speed acquisition unit 317, a vehicle body motion calculation unit 318, and a memory unit 319. The control device 31 performs calculations based on the distance data S obtained from each of the multiple sensors (first sensor Se1 to fourth sensor Se4) and the rotation speed of the drive wheels 22 obtained by the travel control unit 316. Based on the calculation results, the rotation speeds of the motors 221, which are travel actuators arranged on the left and right sides of the vehicle body 11, are controlled so that the vehicle can travel along the ridges B.

[0031] The distance data acquisition unit 311 constituting the control device 31 shown in FIG. 5 will be described. The distance data acquisition unit 311 acquires distance data S obtained from each of the first sensor Se1 to fourth sensor Se4, measuring the distance from the sensor to the ridge B. The distance data acquisition unit 311 recognizes the distance data obtained from the first sensor Se1 to fourth sensor Se4, which is the value of the distance from each sensor to the ridge B, and inputs and outputs the value. The value of the distance data S is used in subsequent calculations.

[0032] 11, the distance data S is composed of first distance data S1 obtained from a first sensor Se1 installed on the front left of the vehicle body 11 in a plan view, second distance data S2 obtained from a second sensor Se2 installed on the front right of the vehicle body 11 in a plan view, third distance data S3 obtained from a third sensor Se3 installed on the rear left of the vehicle body 11 in a plan view, and fourth distance data S4 obtained from a fourth sensor Se4 installed on the rear right of the vehicle body 11 in a plan view. For convenience of explanation, the first distance data S1, second distance data S2, third distance data S3, and fourth distance data S4 may be collectively referred to as distance data S or distance data Si.

[0033] As shown in Fig. 2, the first sensor Se1 to the fourth sensor Se4 are positioned in a rectangular shape that includes a square and a rectangle. Fig. 15 shows a schematic diagram of the relative positional relationship between the ridge B and the sensors, taking into account the passage of time, when each sensor simultaneously acquires distance data S for the ridge B. However, in the embodiment described below, the distance data acquisition unit 311 employs a half-duplex communication method to acquire distance data S from each sensor one by one. Therefore, rather than acquiring distance data S from the first sensor Se1 to the fourth sensor Se4 simultaneously, each sensor measures in turn at a fixed time interval (sampling time, described later). In other words, there is a time difference between the distance data S acquired by the distance data acquisition unit 311 from each of the first sensor Se1 to the fourth sensor Se4.

[0034] Due to the time difference in measurements, the values ​​measured in order from the first sensor Se1 to the fourth sensor Se4 during actual driving are distorted, forming a parallelogram as shown in Figure 16. In other words, taking the passage of time into consideration, the values ​​acquired are those for ridge B and each sensor that are displaced relative to each other. For example, the magnitude of distortion when work vehicle A moves straight is shown in FIG. 16 as follows: V: Straight-line speed obtained from frequency feedback of left motor 221L and right motor 221R, dt: The measurement time difference measured by each sensor. Between the first sensor Se1 and the second sensor Se2, V*dt Between the first sensor Se1 and the third sensor Se3, V*dt+V*dt Between the first sensor Se1 and the fourth sensor Se4, V*dt+V*dt+V*dt Between the first sensor Se1 and the first sensor Se1 after movement, V*dt+V*dt+V*dt+V*dt It is expressed as:

[0035] Therefore, as shown in the time chart of FIG. 16, there is a time difference between the distance data S obtained by the distance data acquisition unit 311 from the first sensor Se1, the second sensor Se2, the third sensor Se3, and the fourth sensor Se4.

[0036] In Figure 14, "write" means the operation of the control device 31 sending a command to start measurement to the sensor that will perform the measurement. "read" means the operation of the control device 31 receiving a response from the sensor that the measurement has ended and storing the received measured distance data S in the memory unit 319. "wait" means the waiting time for the sensor to receive a measurement command sent from the control device 31. "sensor response" is the time it takes for the sensor to measure the distance, and also includes the communication time for sending and receiving the command and the measured distance data S to and from the control device 31. In this embodiment, it is a short time of about 100 milliseconds. However, the time required for sensor response can be changed or modified depending on the sensor specifications and the performance of the control device 31. Measurements are sequentially taken from the first sensor Se1, the second sensor Se2, the third sensor Se3, and the fourth sensor Se4, and the measured data is transmitted to the control device 31.

[0037] For each sensor, there are processes of "write", "sensor response", "read" and "wait". This is repeated in the order of the first sensor Se1, the second sensor Se2, the third sensor Se3, and the fourth sensor Se4. The first sensor Se1 is commanded to start measuring the sensor distance data S ("write"), and after the "sensor response" which is the time required for the actual measurement, the measured distance data S is read ("read"), and after the waiting time ("wait"), the second sensor Se2 is started to "write" in the same way as the first sensor Se1. The same process is carried out for the third sensor Se3 and the fourth sensor Se4. A certain amount of time is required from the start of the "writing" task for the first sensor Se1 until the end of the waiting time for the fourth sensor Se4. In this embodiment, the standard is approximately n milliseconds, less than 1 second. The certain amount of time n can be freely changed or modified depending on the sensor specifications and the performance of the control device 31.

[0038] By repeating these steps, distance data S, which is the measurement result from each sensor, is obtained. The "sampling time" shown in Figure 14 is the time it takes for one sensor to complete storing the measured distance data S in the memory unit and for the control device 31 to successfully communicate with the same sensor again and become able to acquire new distance data S.

[0039] In the first embodiment of the present invention, distance data S is acquired sequentially from the first sensor Se1 to the fourth sensor Se4, so there is a time lag in acquiring the distance data. However, since only one communication port, which is the input unit of the control device 31 that inputs this distance data S, is required, the input unit can be simplified. Furthermore, the distortion of the ridge position measured during actual travel due to the occurrence of the time difference described above is caused by the fact that the measurement time for measuring distance with the ultrasonic sensor used in the embodiment tends to be longer than with other types of sensors, and it takes time for the control device 31 to receive the distance data S. On the other hand, the ultrasonic sensor used in the embodiment handles an extremely small amount of data compared to other types of sensors (particularly three-dimensional distance measurement methods using multiple point clouds obtained from laser light, which is a type of optical sensor, and image recognition using captured images), and therefore the calculation load on the control device 31 can be significantly reduced.

[0040] Furthermore, compared to other types, ultrasonic sensors have a wide detection surface for distance measurement, which prevents excessive detection of small irregularities and easily prevents erroneous measurements due to the color or reflectivity of the object being detected. For these reasons, even a control device 31 with low processing power can perform sufficient processing, and the distance to the object surface can be measured reliably.

[0041] There is a time difference between the distance data S obtained from each of the first sensor Se1 to fourth sensor Se4 and input to the distance data acquisition unit 311. In other words, if calculations are performed directly using the distance data S measured by each sensor, the calculated positional relationship between the ridge B and the work vehicle A will be distorted and different from the actual position. Therefore, a correction value must be calculated and corrected. The correction value is a value calculated from the difference in the relative distance of the vehicle body 11 in the width direction of the ridge B when the vehicle body 11 moves straight from the actual position during the sampling time. The correction values ​​include a straight-line correction value and a turning correction value (rotation correction value). The straight-line correction value indicates the distance by which each wheel is relatively deviated in a direction perpendicular to the ridges when it is assumed that the wheel is moving straight during the sampling time. The turning correction value (rotation correction value) is a value calculated from the difference in the relative angle between the direction of travel of the vehicle body 11 and the direction of the ridge B when the vehicle body 11 is assumed to be turning from its actual position during the sampling time.

[0042] The control device 31 and the storage unit 319 for correcting the distortion of the calculated ridge data due to the time difference occurring in the distance data S input by the distance data acquisition unit 311 will be described. As shown in Figures 5 and 10, the control device 31 has a memory unit 319 that can store vehicle body parameter values ​​P, which are predetermined values ​​including the outer diameter, which is the tire diameter of the drive wheels 22, the tread width, which is the distance between the drive wheels 22, and the gear ratio. The velocity and angular velocity ω are calculated based on the vehicle body parameter value P stored in the storage unit 319 and the measured rotation speed of the motor 221 as shown in FIGS.

[0043] 1 shows a vehicle body motion calculation (odometry) in a motion model of an opposing two-wheel vehicle of a work vehicle A according to a first embodiment of the present invention.

[0044] [Table 1]

[0045] The temporary ridge data generation unit 312 will be described with reference to FIG. 11, which shows the calculation process performed by the temporary ridge data generation unit of the control device 31 of the work vehicle A according to the first embodiment of the present invention. The control device 31 includes a temporary ridge data generating unit 312. The temporary ridge data generating unit 312 calculates the difference between the distance data S obtained from the plurality of sensors by comparing the distance data S indicating the distance to the ridge B. The temporary ridge data generating unit 312 generates the temporary ridge data based on the measurement values. As shown in Figure 11, the temporary ridge data generation unit 312 calculates the difference between the difference in distance data S obtained from the sensor placed on either the left or right side of the direction of travel and the difference in distance data S obtained from the sensor placed on the other left or right side of the direction of travel, thereby calculating the translational position, which is the difference in the relative position of the vehicle body 11 with respect to the width direction of the ridge B, and the ridge angle, which is the relative angular difference between the fore-and-aft direction of the vehicle body 11 with respect to the ridge direction.

[0046] As shown in Figure 11, the temporary ridge data generation unit 312 generates temporary ridge data, which is temporary ridge data, by inputting the first distance data S1 to the fourth distance data S4 obtained from the first sensor Se1 to the fourth sensor Se4, and outputs the temporary ridge data. The temporary ridge data is data calculated using the measured data to determine the relative positional relationship between the vehicle body 11 and the ridge B, and is also called raw data. As mentioned above, each sensor takes measurements in sequence at regular time intervals, resulting in a time difference between the first distance data S1 to the fourth distance data S4. For this reason, the temporary ridge data generated by the temporary ridge data generation unit 312 contains an error in the relative positional relationship between the actual vehicle body 11 and the ridge B while the vehicle is traveling. This error is due to a time difference between the measurements made by each sensor, and tends to become more pronounced as the speed of the work vehicle A is increased.

[0047] As shown in Figure 11, the temporary ridge data generation unit 312 calculates the difference values ​​of the first distance data S1 to the fourth distance data S4 to calculate the translation position indicating how much the vehicle body 11 is shifted relative to the ridge B, which is the object that the vehicle body 11 is following, in the width direction of the ridge B, and the ridge angle indicating how much angle there is relative between the straight-line direction of the vehicle body 11 and the longitudinal direction of the ridge B. In this case, the reference position of the vehicle body 11 passes through the center of the left and right of the vehicle body 11 in a plan view. The reference position is the intersection of a line parallel to the front and rear and a line passing through the midpoint between the first sensor Se1 and the third sensor Se3 and the midpoint between the second sensor Se2 and the fourth sensor Se4. This can also be said to be the center of gravity of the rectangle surrounded by the positions where the first sensor Se1, the second sensor Se2, the third sensor Se3, and the fourth sensor Se4 are arranged.

[0048] Temporary ridge data is generated in a motion model of a work vehicle A with two opposing wheels according to a first embodiment of the present invention.

[0049] [Table 2]

[0050] The following terms used in Figures 7, 11 and other figures have the following meanings: Distance data Si (i=1, 2, 3, 4...): The value of the distance to the ridge obtained from the sensor. In the embodiment, it is represented by first distance data S1, second distance data S2, third distance data S3, and fourth distance data S4. Front difference SF: The difference between the first distance data S1 and the second distance data S2 (the difference between the distances from the sensors arranged on the left and right sides of the front to the sides of the ridges). In the embodiment, the difference is expressed as a sum. Rear difference SB: The difference between the third distance data S3 and the fourth distance data S4 (the difference between the distances from the sensors arranged on the left and right rear sides to the ridge sides). In the embodiment, the difference is expressed as a sum. Left difference SL: The difference between the first distance data S1 and the third distance data S3 (the difference between the distances from the sensors arranged in front and behind on the left side to the side of the ridge). In the embodiment, the difference is expressed as a sum. Right difference SR: The difference between the second distance data S2 and the fourth distance data S4 (the difference between the distances from the sensors placed in front and behind on the right side to the side of the ridge). In the embodiment, the difference is expressed as a sum. Sensor distance Sy: The relative front-to-rear distance between the front and rear sensors. In this embodiment, the front-to-rear distance between the sensors arranged on the left and right sides is the same. In addition, if the distance between the left and right sensors differs due to the influence of an asymmetrical arrangement, individual parameters for the distance between the left and right sensors are used.

[0051] Translation position T: A value that represents the difference between the left difference SL and the right difference SR. Regarding the positional relationship between the ridge and the vehicle body, this value represents how much the vehicle body is misaligned relative to the width direction of the ridge. In other words, if the value of translation position T is 0, the vehicle body is not misaligned relative to the ridge. Note that in this case, the angular difference between the straight-ahead direction, which is the fore-and-aft direction of the vehicle body, and the longitudinal direction of the ridge is not included. Pre-ratio PF: A ratio value calculated using the first distance data S1, the second distance data S2, and the pre-difference SF, and is a dimensionless quantity. Post ratio PB: A ratio value calculated using the third distance data S3, the fourth distance data S4, and the post difference SB, and is a dimensionless quantity. Ridge angle θ: The ridge angle θ shown in Figure 7 is calculated as the angle between the straight-line direction (front-to-rear direction of the vehicle body) and the longitudinal direction of the ridge using the front ratio PF, rear ratio PB, and sensor distance Sy calculated based on the distance data S1, S2, S3, and S4 obtained from the first to fourth sensors. Temporary ridge data: The values ​​calculated using the measured data, namely, the front difference SF, rear difference SB, left difference SL, right difference SR, front ratio PF, rear ratio PB, sensor distance Sy, translation position T, and ridge angle θ, are called temporary ridge data.

[0052] By determining the ridge angle θ based on the front proportion PF and the rear proportion PB, an accurate value of the ridge angle θ can be obtained even if distortion occurs such that the width of the ridges B is not constant at the front and rear of the vehicle body 11. The storage unit 319 stores data specific to the vehicle body 11, such as the outer diameter of the wheels, the reduction ratio in the reduction unit 222, the tread width of the drive wheels 22, and the coordinates of the sensor placement positions (sensor distances). In addition, the various calculation results calculated by the control device 31 can also be temporarily stored.

[0053] The control device 31 includes a vehicle body motion calculation unit 318 . The vehicle body motion calculation unit 318 shown in FIG. 8 is a diagram showing the control process in the control device 31 of the work vehicle A according to the first embodiment of the present invention, and FIG. 10 is a diagram showing the calculation process by the vehicle body motion calculation unit 318 of the control device 31. The vehicle body motion calculation unit 318 is shown in FIG. The vehicle body motion calculation unit 318 receives as input the rotation speed of the motor 221 that drives each drive wheel 22 from the rotation speed acquisition unit 317. It also receives as input data specific to the vehicle body 11, such as the outer diameter of the wheel, the reduction ratio in the reduction unit 222, and the tread width of the drive wheels 22, stored in the memory unit 319. The vehicle body motion calculation unit 318 calculates a current vehicle body parameter value P from the rotation speed of each of the left and right motors 221 and the specific data of the vehicle body 11. The vehicle body parameter value P is the traveling speed of each drive wheel 22, calculated based on the peripheral speed obtained from the rotation speeds of the left and right drive wheels 22. The vehicle body motion calculation unit 318 calculates a straight-line speed V, which is the speed component in the straight-line direction of the vehicle body 11, and an angular speed ω, which is the speed component in the turning direction of the vehicle body 11, calculated from the traveling speed of each drive wheel 22. As shown in Fig. 10, the vehicle body motion calculation unit 318 outputs the straight-line speed V and angular speed ω calculated based on the vehicle body parameter value P as vehicle body momentum, which is the physical amount by which the vehicle body 11 has moved. Vehicle body momentum is sometimes called odometry.

[0054] The vehicle body motion calculation unit 318 calculates the vehicle body momentum of the vehicle body 11 based on the left rotation speed NL and the right rotation speed NR obtained from each of the drive wheels 22, as shown in FIG. The rotation speed acquisition unit 317 acquires the rotation speed of the motor 221, which is a traveling actuator, from the traveling control unit 316 that controls the rotation speed of the left rotation speed NL and the right rotation speed NR of the motor 221 that drives each driving wheel 22.

[0055] The vehicle body momentum shown in FIG. 12 will be described. The vehicle momentum includes a traveling speed calculated for each of the drive wheels 22 from the rotation speed of the drive wheels 22, and an angular velocity ω calculated based on the traveling speed calculated for each of the drive wheels 22. In order to explain the control process of the work vehicle A according to the first embodiment of the present invention, reference will be made to FIG. 7, which is an explanatory diagram that schematically shows the positional relationship between the work vehicle A and the ridges. Travel speeds VL, VR: Calculated for each drive wheel based on the tire diameter Dw stored in the memory unit and the rotation speeds NL, NR for the left and right drive wheels obtained from the rotation circumference acquisition unit. Expressed as the travel speed VL of the left drive wheel and the travel speed VR of the right drive wheel. Straight-line speed V: Calculated as the average value of the travel speeds VL and VR of each drive wheel. Angular velocity ω: Calculated from the difference between the travel speeds VL and VR of the respective drive wheels and the tread width Dt stored in the memory unit. Vehicle body momentum: A general term including the rectilinear velocity V and angular velocity ω, which is the physical amount by which the vehicle body 11 moves.

[0056] The driving control unit 316 will now be described. In this embodiment, the driving control unit 316 is configured with an inverter, and modulates and controls the output frequency of the AC voltage to output the voltage, thereby controlling the rotation speed of the motor 221. The driving control unit 316 controls the rotation speed of the motor 221, and at the same time outputs information obtained from the motor 221 to the rotation speed acquisition unit 317. The rotation speed acquisition unit 317 obtains the rotation speed of the motor 221 based on information about the frequency that is actually being output, obtained from the driving control unit 316.

[0057] The sensor coordinate correcting section 313 will be described with reference to FIG. 12, which shows the calculation process performed by the sensor coordinate correcting section of the control device 31 of the work vehicle A according to the first embodiment of the present invention. The control device 31 includes a sensor coordinate correction unit 313. Based on the vehicle body momentum and the provisional ridge data, the sensor coordinate correction unit 313 calculates the amount of deviation between the actual position, which is the position where the distance to the ridge B is actually measured by the sensor, and the current position where the vehicle body 11 has moved from the actual position by the sampling time t. Then, the control device 31 calculates a correction value based on the amount of deviation. As shown in Figure 12, which shows the calculation process by the sensor coordinate correction unit of the control device 31 of the work vehicle A in the first embodiment of this invention, the sensor coordinate correction unit 313 inputs the vehicle momentum and provisional ridge data, and performs calculations based on these to calculate correction values ​​for correcting the distance data Si measured by each sensor, and outputs corrected distance data S'.

[0058] The sensor coordinate correction unit 313 calculates an estimated movement distance when the vehicle body 11 moves in the straight-line direction at the sampling time t, and an estimated turning angle when the vehicle body 11 continues turning in the turning direction, based on the input vehicle body momentum, i.e., the straight-line speed V and the angular speed ω. The movement distance is an estimated movement amount relative to a translational position when the vehicle body 11 is assumed to move at the straight-line speed V during the sampling time t, and is in an integrated relationship with the control period. The turning angle is an estimated movement amount relative to an angle when the vehicle body 11 turns while maintaining the angular speed ω during the sampling time t, and is in an integrated relationship with the control period.

[0059] As shown in Figure 8, the control cycle refers to a series of operational cycles from inputting distance data S obtained from a certain sensor into the control device 31 to controlling the motor 221 based on the results of various calculations. Within this control device 31, the distance data acquisition unit 311 receives the distance data S from the sensor, and the provisional ridge data generation unit 312 generates provisional ridge data. The sensor coordinate correction unit 313 generates a correction amount from this provisional ridge data and the vehicle momentum obtained from the current rotation speed of the motor 221 by the vehicle momentum calculation unit 318. The ridge data generation unit 314 then generates ridge data based on this correction amount, and calculates the target speed at which the vehicle should move. The travel control unit 316 sends rotation speed commands to the left motor 221L and right motor 221R so that the rotation speed will achieve this target speed, and the motor 221 rotates based on this command, causing the work vehicle A to travel along the ridge.

[0060] The sampling time t will be further explained. This is a calculation of the sensor correction amount based on the motion in the motion model of the oncoming two-wheel vehicle of the work vehicle A according to the first embodiment of the present invention. That is, it shows the calculation contents performed by the sensor coordinate correction unit 313.

[0061] [Table 3]

[0062] The sensor coordinate correction unit 313 calculates the change in the relative distance between the machine body and ridge B that can be estimated over time in relation to the vehicle momentum based on the input temporary ridge data, the calculated transport distance and turning angle, and the coordinates of each mounting position of the first sensor Se1 to the fourth sensor Se4 stored in the memory unit 319. The sensor coordinate corrector 313 calculates a correction value for the vehicle body 11 to travel parallel to the ridge B based on the change in the relative distance to the ridge B and the positional relationship after the estimated sampling time t has elapsed. As shown in FIG. 12, the correction value is calculated based on the momentum of the vehicle body 11 as a result of actual measurement, thereby creating and outputting corrected distance data S'. The corrected distance data S' is data obtained based on correction values ​​calculated for each of the distance data S measured by the first sensor Se1 to the fourth sensor Se4 at different times. In other words, the corrected distance data S' is distance data as if the first sensor Se1 to the fourth sensor Se4 had all measured the distance to the ridge B simultaneously and continuously. In this embodiment, the corrected distance data S' includes first corrected distance data S1', second corrected distance data S2', third corrected distance data S3', and fourth corrected distance data S4'. For convenience of explanation, the first corrected distance data S1', the second corrected distance data S2', the third corrected distance data S3', and the fourth corrected distance data S4' may be collectively referred to as corrected distance data S' or corrected distance data Si' (i=1, 2, 3, 4).

[0063] Figure 13 is a visual representation of an example of distance data and corrected distance data. In Figure 13, (1) shows distance data measured by one sensor, and (2) shows corrected distance data obtained as a result of correcting the distance data measured by one sensor. In both (1) and (2), the horizontal axis represents the passage of time, and the vertical axis represents the measured distance. Figure 13 (1) shows a graph with a rectangular wave shape. This occurs because one sensor periodically measures only a certain moment during the control cycle. In other words, this indicates that the sensor is not able to continuously measure the distance between moving work vehicle A and ridge B. In contrast, (2) in Figure 13 shows a piecewise smooth graph formed by a correction calculation. This shows that the distance between work vehicle A and ridge B, which is moving during times when the sensor is not measuring, has been corrected as if it had been measured. By calculating the corrected distance data, work vehicle A can be made to behave as if it had continuously measured the distance to ridge B, making it possible for work vehicle A to travel along ridge B with high accuracy.

[0064] Based on the vehicle body momentum and the provisional ridge data, the sensor coordinate correction unit 313 calculates the deviation between the actual position, which is the position where the distance to the ridge is actually measured by the sensor, and the current position moved from the actual position by the sampling time t, which is the time it takes for the vehicle body 11 to receive the newly measured distance data S at the control device 11, and calculates a correction value based on the deviation. Sampling time t: The periodic time from when a sensor stops operating and the distance data acquisition unit 311 finishes reading the distance data S until it starts operating again and begins reading the distance data S again is called the sampling time t. A given sensor operates for a certain period of time after starting operation, during which it performs measurement, and then ends the measurement operation after the operation time. Then, the next sensor operates and performs measurement, repeating this cycle until the time immediately before the start of operation of the sensor that first started measurement. In this embodiment, the first to fourth sensors Se1 to Se4 are operated in the following order: first sensor Se1, second sensor Se2, third sensor Se3, and fourth sensor Se4. The operation order is merely an example, and other combinations of the order are also possible, such as the fourth sensor Se4, third sensor Se3, second sensor Se2, and first sensor Se1, or the first sensor Se1, fourth sensor Se4, second sensor Se2, and third sensor Se3.

[0065] In the embodiment, the control device 31 is simplified by having only one communication port, which is an input / output unit for the sensors, and therefore the first sensor Se1 to the fourth sensor Se4 are operated sequentially. If it is possible to add input / output units or communication ports to the control device 31, multiple sensors may be operated simultaneously, for example, by operating the first sensor Se1 and the second sensor Se2 simultaneously, and then operating the third sensor Se3 and the fourth sensor Se4 simultaneously. Of course, the combination of sensors operated simultaneously, the order of their operation, and each combination may be changed. Furthermore, when using the sensor method of the embodiment, it is desirable to stagger the timing at which the sensors operate to prevent interference between ultrasonic waves, measurement range, measurement effects due to reflected waves, and other characteristics.

[0066] The periodic time until these sensors operate simultaneously can also be set as the sampling time t. In the embodiment, the sampling time t is set to 450 milliseconds, but this can be freely changed depending on the configuration of the aircraft and the control configuration of the control device 31. Travel distance L: The estimated travel distance of each wheel (22, 23) at sampling time t when it is assumed to have traveled in a straight line, and is in an integrated relationship with the straight line speed V of the vehicle body 11 and the control period.

[0067] Turning angle φ: the estimated turning angle of each wheel (22, 23) at sampling time t when it is assumed that the wheel has turned in the turning direction, and is in a cumulative relationship with the angular velocity ω of the vehicle body 11 and the control period. 7, in this embodiment, the turning center O of the vehicle body 11 in a plan view is set approximately in a calculation to be midway between the drive wheels 22 and coincide with the center of the rotation axis about which the drive wheels 22 rotate. Depending on the configuration of the running unit 21, the turning center O can be set to any position, for example, a midway between the drive wheels 22 and a position shifted in the front-to-rear direction from the rotation axis about which the drive wheels 22 rotate. Center distance Ri (i=1, 2, 3, 4, etc.): As shown in FIG. 7, R1, R2, R3, and R4 indicate the linear distance between each sensor (Se1, Se2, Se3, and Se4) and the center of rotation O. In the example, the number i indicated by the center distance Ri corresponds to the number m indicated by the m-th sensor Sem.

[0068] Straight-line correction value SVi (i = 1, 2, 3, 4, etc.): For each wheel (22, 23), this indicates the distance by which the wheel is relatively deviated in the direction perpendicular to the ridge B when it is assumed that the wheel has traveled straight during the sampling time t. It is correlated with the travel distance L, the ridge angle θ, and the turning angle φ. The straight-line correction value SVi is reset to 0 after one cycle of the sampling time t, and is calculated using the value measured again. In the example, the number i indicated by the straight-line correction value SVi corresponds to the number m indicated by the mth sensor Sem.

[0069] Rotation correction value (turning correction value) Sωi (i = 1, 2, 3, 4, etc.): For each wheel (22, 23), this indicates the distance by which the wheel is relatively shifted in the direction perpendicular to the ridge B when it is assumed that the wheel has turned during the sampling time t. It is correlated with the center distance Ri and the turning angle φ. The rotation correction value (turning correction value) Sωi is reset to 0 after one cycle of the sampling time t, and is calculated using the value measured again. In the example, the number i indicated in the rotation correction value Sωi corresponds to the number m indicated in the mth sensor Sem.

[0070] Correction value Sfi (i=1, 2, 3, 4, . . .): For each wheel (22, 23), the sum of the straight-line correction value SVi and the rotation correction value (turning correction value) Sωi indicates the current value to be corrected. In the example, the number i indicated by the correction value Sfi corresponds to the number m indicated by the m-th sensor Sem. Corrected distance data Si' (i = 1, 2, 3, 4, ...): Value obtained by correcting the distance data Si between each sensor and the ridge B actually measured for each wheel (22, 23) using the correction value Sfi. In the embodiment, the corrected distance data Si' is a value obtained by adding or subtracting the correction value Sfi to the distance data Si. In the embodiment, it is represented by corrected first distance data S1', corrected second distance data S2', corrected third distance data S3', and corrected fourth distance data S4'. In the example, the number i indicated in the corrected distance data Si' corresponds to the number m indicated by the mth sensor Sem.

[0071] The ridge data generating unit 314 will be described. When the ridge data generation unit 314 receives the corrected distance data S' calculated by the sensor coordinate correction unit 313, it calculates the translation distance and ridge angle based on the corrected distance data S', in the same way as the calculations by the temporary ridge data generation unit 312. The translation distance calculated using this corrected distance data S' is called the corrected translation distance, and similarly, the ridge angle is called the corrected ridge angle. Using the corrected translation distance and corrected ridge angle, the ridge data generation unit 314 derives the relative position and angular relationship between the work vehicle A and ridge B, assuming that the first sensor Se1 to the fourth sensor Se4 all measured the distance to ridge B at the same time.

[0072] The ridge data generating unit 314 performs the following calculations based on the corrected data. Pre-correction difference SF': difference between corrected first distance data S1' and corrected second distance data S2'. In the example, expressed as a sum. Corrected difference SB': the difference between the corrected third distance data S3' and the corrected fourth distance data S4'. In the example, this is expressed as a sum. Corrected left difference SL': the difference between the corrected first distance data S1' and the corrected third distance data S3'. In the example, this is expressed as a sum. Corrected right difference SR': the difference between the corrected second distance data S2' and the corrected fourth distance data S4'. In the example, this is expressed as a sum. Pre-correction ratio PF': A ratio value calculated using the corrected first distance data S1', the corrected second distance data S2', and the pre-correction difference SF, and is a corrected dimensionless quantity. Corrected ratio PB': A ratio value calculated using the corrected third distance data S3', the corrected fourth distance data S4', and the previous difference SB, and is a corrected dimensionless quantity. Corrected translation position T': A value that represents the difference between the corrected left difference SL' and the corrected right difference SR'. This is a value calculated to determine how much the vehicle body is shifted relative to the ridge in the width direction of the ridge, and is a value corrected taking into account the actually measured time difference. Corrected ridge angle θ': This is the value calculated using the pre-correction ratio PF', the post-correction ratio PB', and the sensor distance Sy to determine the relative angle between the straight-line direction (the fore-and-aft direction of the vehicle body) and the longitudinal direction of the ridge, and is a value corrected taking into account the time difference actually measured.

[0073] This shows the calculation contents of the ridge data generation unit 314 in the motion model of the work vehicle A in the first embodiment of the present invention when it is an opposing two-wheel vehicle. This calculation is performed based on the pre-correction difference SF', post-correction difference SB', corrected left difference SL', corrected right difference SR', pre-correction ratio PF', and post-correction ratio PB', and is the same type of calculation as that performed by the temporary ridge data generation unit 312 to calculate the corrected translation position T' and the corrected ridge angle θ'.

[0074] [Table 4]

[0075] In this embodiment, the arrangement of the vehicle body 11, motor 221, running unit 21, and sensors (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4) is the same as that of the configuration of Patent Application No. 2024-27348 "Work Vehicle" (hereinafter referred to as the previous application) filed by the applicant of the present application, but compared to the configuration of the same application, as shown in Figure 6, the control amount calculation unit 315 constituting the control device 31 further includes a target value generation unit 3151, a PID control unit 3152, a vehicle speed determination unit 3153, and a turning radius regulation unit 3154. The process for generating ridge data is the same as in the previous application up to [Table 4].

[0076] In this embodiment, by performing the calculation of the invention before the rotational speed calculation (Table 11) described below, even when entering a large curve or when the running part 21 and the ridge B are close to each other, it is possible to perform a gentle turning motion and allow the vehicle body 11 to follow the ridge B without coming into contact with it. In this embodiment, deceleration control is performed when the positional deviation at a curve or the like during ridge-following travel is greater than a predetermined value. The predetermined value is a value that can change the degree of deceleration when the positional deviation between the vehicle body 11 and the ridge B is proportional to or causally related to the magnitude of the target value P, and deceleration control is performed according to the positional deviation of the vehicle body by comparing it with the calculation result.

[0077] An outline of the control flow according to the embodiment of the present invention will now be described. In this embodiment of the present invention, the control is performed in the following order: Obtain distance data → Calculate vehicle motion ([Table 1]) · Obtain rotation speed → Generate temporary furrow data ([Table 2]) → Calculate correction amount ([Table 3]) → Generate furrow data ([Table 4]) → Calculate target value ([Table 5]) → PID control calculation ([Table 6]) → Calculate vehicle speed ([Table 7]) → Calculate turning radius ([Table 10]) → Calculate rotation speed ([Table 11]) → Calculate frequency ([Table 12])

[0078] The target value generation calculation shown in [Table 5] will be explained. The corrected translation position T' and corrected ridge angle θ' obtained by the ridge data generation unit are acquired by the target value generation unit 3151. The target value generation unit 3151 calculates and generates a target value P that corrects the corrected translation position T' to 0 or approximately 0, assuming that the vehicle body 11 is oriented parallel to the ridge B. Given that gain Kα is a preset numerical value that is the amount of translation to be applied, and gain Kβ is a preset numerical value that is the amount of angle to be applied, the target value P for the translation position is expressed by the following equation.

[0079] [Table 5]

[0080] For example, when the angular error between the direction of ridge B and the direction of travel of vehicle body 11 is small, so that the direction of ridge B and the direction of travel of vehicle body 11 are approximately parallel, and the position of vehicle body 11 is shifted in a direction perpendicular to ridge B, it is necessary to correct the translational position. In order to be able to correct the translational position even when the angular error between the direction of the ridge B and the traveling direction of the vehicle body 11 is small, it is desirable that the magnitude relationship between the gain Kα and the corrected translational position T', and the gain Kβ and the corrected ridge angle θ', satisfy the relationship of the formula written in the parentheses above. In other words, the multiplication value of the gain Kα and the corrected translational position T' is set to be very small compared to the multiplication value of the gain Kβ and the corrected ridge angle θ'. The gains Kα and Kβ are set in advance to satisfy the above relationship, stored in a memory unit, and used in calculations.

[0081] The gain Kα is preferably a value between 0.10 and 0.25, with the most preferred value being 0.18 in this embodiment. The gain Kβ is preferably a value between 0.75 and 0.90, with the most preferred value being 0.82 in this embodiment. The gain Kα is set to be approximately 3 to 8 times the gain Kβ. Therefore, the value expressed by the gain Kα and the corrected translational position T' is calculated to be smaller than the value expressed by the gain Kβ and the corrected ridge angle θ'. In terms of the calculation formula, the target value P is calculated based on the values ​​of gain Kα and gain Kβ, which makes it appear as if the calculated value for the corrected ridge angle θ' is larger than the calculated value for the corrected translation position T'. However, when considering a case where the angle error between the direction of ridge B and the traveling direction of the vehicle body 11 is small, the corrected ridge angle θ' itself is obtained from the sensor and ridge data generation unit 314 as a very small value. Therefore, even if the gain Kα is a value relatively smaller than the gain Kβ, the reliability of the calculation result that emphasizes the corrected translational position T' can be ensured. As a result, the target value P becomes a value that makes it possible to correct the translational position even when the angle error between the ridge B and the vehicle body 11 is small. The values ​​of the gain Kα and the gain Kβ can be changed as appropriate depending on the type of work vehicle to be applied.

[0082] The PID control calculations shown in Table 6 will now be explained. PID control calculations are performed by the PID control unit 3152. PID control (Proportional Integral Differential control) is a feedback control that controls the input value using the deviation, integral, and derivative between the output value and the target value. This allows the vehicle body 11 to be controlled to travel precisely along the furrow B. When the PID control unit 3152 obtains the target value P calculated by the target value generation unit 3151, it calculates and generates the turning target value Pω. The turning target value Pω is a value that indicates the turning angle per unit time. In addition to the above examples, calculations may be performed using a combination of PI control and PD control, or either one of them, or modern control using an optimal regulator, etc.

[0083] The turning target value Pω is calculated using the following formula using a gain KP, which is a predetermined value indicating a deviation, a gain KI, which is a predetermined value indicating a steady-state deviation, a gain KD, which is a predetermined value indicating responsiveness, and the generated target value P.

[0084] [Table 6]

[0085] The gains Kα, Kβ, KP, KI, and KD used in the target value generation calculation and PID control calculation are set so that they can be changed as appropriate depending on the state of the work vehicle A. For example, they are set in advance to suit each situation depending on vehicle characteristics such as the dimensional distance between the wheels of the tread and wheelbase, the placement distance of the sensors (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4), and differences in the configuration of the traveling unit 21, as well as the traveling environment, and are stored in the memory unit. The target value P is generated using the gain Kα, corrected translational position T', gain Kβ, and corrected ridge angle θ'.

[0086] The calculation for determining the vehicle speed shown in [Table 7] will now be described. The vehicle speed determination unit 3153 calculates a corrected speed Pv', which is a speed corrected for the target speed Pv set by the operator, based on the target value P generated by the target value generation unit 3151, and determines the vehicle speed.

[0087] First, before calculating the corrected speed Pv', the generated target value P is subjected to low-pass filtering by a low-pass filter 3157. In the low-pass filtering, the following calculation is performed to generate a filtered target value Rp, which is a new target value.

[0088] [Table 7]

[0089] The filtered target value Rp is calculated using a filter coefficient α, which is a preset numerical value, and a filter coefficient β, which is also a preset numerical value. In this calculation, the target value P is calculated using a current target value Pt and a previous target value Pt-1. Of the target values ​​P obtained by periodic calculation processing at a cycle time of sampling time t, the current target value Pt obtained in the current calculation is used, and the previous target value Pt-1 obtained in the previous calculation is used to calculate the filtered target value Rp.

[0090] As shown in the formula in parentheses, the filter coefficients α and β are values ​​whose sum is 1 when added together, and the filter coefficient α is set to a value much smaller than the filter coefficient β. The filter coefficient α is preferably a value between 0.02 and 0.20, with 0.10 being the most preferred value in this embodiment. The filter coefficient β is preferably a value between 0.80 and 0.98, with 0.90 being the most preferred value in this embodiment. The filter coefficient α is set to be 4 to 40 times the filter coefficient β, with 9 times being set in this embodiment. Furthermore, due to the relationship between the filter coefficients α and β, the filtered target value Rp can be said to be a value that results from a calculation that places more emphasis on the previous target value Pt-1 than on the current target value Pt. By setting the filter coefficients α and β, the work vehicle A can suppress pulsation in its driving behavior and achieve smooth driving.

[0091] The control device 31 is equipped with a ridge data generation unit 314 that calculates a corrected translational position T' and a corrected ridge angle θ' that indicate the relative position between the vehicle body 11 and the ridge B based on the measurement values, and a target value generation unit 3151 that calculates a target value based on the corrected translational position T' and the corrected ridge angle θ', and the value expressed by the relationship between the gain applied to the corrected translational position T' and the corrected translational position T' is much smaller than the value expressed by the relationship between the gain applied to the corrected ridge angle θ' and the corrected ridge angle θ' means the above.

[0092] The filter coefficients α and β are set so that they can be changed as appropriate depending on the state of the work vehicle A. For example, they are set in advance to suit each situation depending on vehicle characteristics such as the dimensional distance between the wheels of the tread or wheelbase, the placement distance of the sensors (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4), and differences in the configuration of the traveling unit 21, as well as the traveling environment, and are stored in the memory unit. Furthermore, the filter coefficients α and β are numerical values ​​that can be freely changed and adjusted, taking into account the update rate of the target value P and responsiveness to noise.

[0093] Furthermore, the vehicle speed determination unit 3153 shown in Table 8 calculates a correction amount Rv, which is a value for correcting the target speed Pv, to derive the corrected speed Pv'. The correction amount Rv is derived by the following calculation using the filtered target value Rp and an application amount Kv, which is a preset numerical value.

[0094] [Table 8]

[0095] As shown in the above formula, the correction amount Rv is the value obtained by dividing the filtered target value Rp by the application amount Kv. The correction amount Rv is a value between 0 and 1, and is calculated so as to be equal to or less than the application amount Kv. Then, using the correction amount Rv calculated by the above calculation as shown in [Table 9], the corrected speed Pv' obtained by correcting the target speed Pv is derived by the following calculation formula.

[0096] [Table 9]

[0097] When the deviation between the work vehicle A and the target value P is greater than a predetermined value, the vehicle speed determination unit 3153 calculates Pv' using the generated filtered target value Rp, thereby controlling the work vehicle A to decelerate and proceed. An example of this situation is when ridge B and work vehicle A are significantly misaligned in the direction of ridge B, or when work vehicle A is entering a curved ridge B. In this way, work vehicle A can travel along ridge B while autonomously adjusting its speed relative to the set speed of work vehicle A so that it can travel appropriately depending on the condition of ridge B and the relative positions of ridge B and work vehicle A.

[0098] A more specific example will be given. Suppose that ridge B is positioned unevenly on either the left or right side of the traveling section 21, and that ridge B and the direction of travel of work vehicle A are parallel. In this case, the relative position of work vehicle A with respect to ridge B is misaligned, so work vehicle A attempts to move forward while turning to one side in order to make the translation position and ridge angle zero. In this case, turning to one side increases the ridge angle, which in turn causes work vehicle A to try to turn to the other side, and the positional relationship with ridge B may not be properly corrected. However, by performing the calculations of the present invention, work vehicle A is adjusted to reduce its speed while traveling, so the relative positional relationship between work vehicle A and ridge B is unlikely to change significantly, and extreme hunting behavior does not occur in the control. As a result, work vehicle A can be made to travel gradually closer to ridge B while slowing down from the set speed.

[0099] Since the vehicle travels at a reduced speed, it is possible to respond in time to a turning movement when the traveling vehicle body 11 approaches a curved ridge B. In other words, the traveling part 21 can turn along the ridge B without coming into contact with the ridge B. Furthermore, even if the control unit recognizes that the position or angle between the ridge B and the vehicle body 11 is significantly misaligned due to erroneous measurement or error as a result of sensor measurement, it is possible to increase the number of sampling times to remeasure the distance between the ridge B and the vehicle body 11 while traveling at a reduced speed. Therefore, it is possible to reduce the chance of the positional relationship between the ridge B and the vehicle body 11 moving in the wrong direction.

[0100] In this way, not only is the speed of the left and right wheels adjusted, but the overall vehicle speed is also adjusted, so the greater the deviation, the slower work vehicle A can move, allowing it to travel smoothly along ridge B. In other words, work vehicle A can be controlled to travel carefully, taking into account the positional relationship between ridge B and its own vehicle.

[0101] In addition, by performing the above calculations, it is possible to prevent the vehicle speed from repeatedly increasing and decreasing in a pulsating manner due to the influence of the terrain, noise, etc., as a result of measuring the distance of ridge B with the sensor, and to allow the vehicle to travel smoothly along ridge B.

[0102] The turning radius restricting portion 3154 shown in Table 10 will now be described. In this embodiment, the running part 21 has caster wheels on either the front or rear side, with driven wheels 23 that can rotate horizontally around a vertical axis. When the vehicle body 11 is turned using the above calculations, the horizontal rotation of the driven wheels 23 may cause the driven wheels 23 to come into contact with the ridge B. Therefore, by restricting the turning radius, it is possible to make the vehicle body 11 run along the ridge B without the running part 21 coming into contact with the ridge B. The turning radius restricting unit 3154 calculates the turning restriction angular velocity ωlim, which is the limit value at which the body 11 can turn, according to the following equation, based on the corrected velocity Pv' generated by the vehicle speed determining calculation unit and the turning radius r.

[0103] [Table 10]

[0104] As in the above formula, if the value of the corrected speed Pv' is greater than the value of the turning restriction angular speed ωlim, which is a pre-assumed value, the value of the corrected speed Pv' and the value of the turning restriction angular speed ωlim are considered to be the same value and are calculated. The turning radius r is a numerical value that is set in advance and stored in the memory unit, and is the limit value of the radius at which the vehicle body 11 turns. The turning radius r is a value that is artificially set based on the relative distance relationship between the tread width of the running portion 21, the wheelbase, and the ridge width.

[0105] To explain in more detail, when the tread width is sufficiently wider than the ridge width or when the ridge bottom width between ridges B is wide, the distance between the drive wheels 22 and driven wheels 23 and the ridge side surfaces can be made large, so even when turning with a small turning radius, there is little risk of the drive wheels 22 and driven wheels 23 coming into contact with the ridge B. Focusing on the driven wheels 23, the range within which the driven wheels 23 can rotate horizontally as they move in response to turning can be increased. In other words, since the driven wheels 23 are less likely to come into contact with the ridges, the turning radius r in this case can be set to a small value. Conversely, when the tread width is only slightly wider than the ridge width, the distance between the drive wheels 22 and driven wheels 23 and the ridge side surfaces is small, and unless the turning radius is made large when turning, the drive wheels 22 and driven wheels 23 are more likely to come into contact with the ridge B. Focusing on the driven wheels 23, it is necessary to reduce the range within which the driven wheels 23, which move in response to turning, can rotate horizontally, thereby preventing the driven wheels 23 from approaching the ridges B. In other words, in this case, the turning radius r needs to be set to a large value.

[0106] Similarly, when the wheelbase, which is the distance between the drive wheels 22 and the driven wheels 23, is short, even if the turning radius r is reduced during turning, the turning distance traveled by the driven wheels 23 per unit time is short, allowing a long time for the driven wheels 23, which move left and right together with the vehicle body 11, to come into contact with the ridges B. Therefore, even if the turning radius r is reduced, there is a long time to correct the turning direction along the ridges B, allowing the vehicle to correct the turning direction and travel correctly along the ridges B. Conversely, when the wheelbase is long, when the turning radius r is reduced during turning, the turning distance traveled by the driven wheels 23 per unit time during turning is long, so the time for the driven wheels 23, which move left and right together with the vehicle body 11, to come into contact with the ridges B is shorter than when the wheelbase is short. There is little time to correct the turning direction along the ridges B, and it may not be possible to correctly correct the turning direction along the ridges B. Of course, if the relationship between tread width and ridge width changes, the relationship between wheelbase and turning radius r will also change.

[0107] In this way, it is desirable to set the turning radius r in advance, taking into consideration the tread width, wheelbase, and furrow width. The turning radius r can be freely changed depending on the type and specifications of the work vehicle A to be applied, as well as the furrow width and shape.

[0108] The turning radius restriction unit 3154 calculates the turning restriction angular velocity ωlim based on the corrected velocity Pv' and the turning target value Pω, and the rotational velocity calculation unit 3155 calculates the peripheral velocity of the drive wheels 22. The rotational velocity calculation unit 3155 then calculates the odometry backward to determine the rotational speed of the drive wheels 22 (Table 5). The angular velocity ω is calculated so as not to exceed the turning restriction angular velocity ωlim. To explain in more detail, in control, there may be a difference between positive and negative values ​​due to differences in the turning direction between positive and negative directions. For this reason, it is necessary to calculate the absolute value of the angular velocity ω during turning so that it does not exceed the absolute value of the turning restriction angular velocity ωlim, and to perform turning control. If the absolute value of the angular velocity ω exceeds the absolute value of the turning restriction angular velocity ωlim, the angular velocity ω during turning is calculated as being equal to the turning restriction angular velocity ωlim, and turning control is performed.

[0109] After the calculation in the turning radius regulation unit 3154, the frequency calculation unit 3156 calculates the frequency that the inverter will use to command the motor 221, and the inverter can rotate the motor 221 at the calculated frequency (Table 12).

[0110] The rotation speed calculation unit 3155 shown in Table 11 will be explained. This is a rotational speed calculation unit 3155 in a motion model of a two-wheel opposing vehicle of work vehicle A according to the first embodiment of the present invention. The calculations in rotational speed calculation unit 3155 are performed based on the results obtained in control amount calculation unit 315. Rotational speed calculation unit 3155 calculates the rotational speed of each of drive wheels 22 arranged on the left and right.

[0111] [Table 11]

[0112] This is frequency calculation section 3156 in the motion model of an oncoming two-wheel vehicle of work vehicle A according to the first embodiment of the present invention. As shown in Table 12, the calculations of frequency calculation section 3156 are performed by travel control section 316.

[0113] [Table 12]

[0114] The control amount calculation unit 315 will be further described. Target value P: A value obtained by determining the amount that work vehicle A should correct from the corrected translational position T' and corrected ridge angle θ'. Filtered target value Rp: A target value calculated using filter coefficients α and β, taking into account the sampling time t. Target turning speed Pω: This is the target speed in the turning direction for work vehicle A to make corrective movements relative to the furrows. Target straight-line speed Pv: This is the target speed in the forward and backward directions for work vehicle A to correct its movement relative to the furrows. Target rotation speeds NL', NR': These are the rotation speeds at which each drive wheel should rotate in order for work vehicle A to move correctly relative to the furrows. These are values ​​calculated based on the target straight-line speed Pv and the target turning speed Pω. The control amount calculation unit 315 calculates a target value P that will achieve the relative position and direction relationship between the work vehicle A and the ridge B that should be the target, based on the corrected translation distance T' and corrected ridge angle θ' derived by the ridge data generation unit 314. Furthermore, based on this target value P, it generates a filtered target value Rp.

[0115] The target value P is a value calculated so that the corrected translational position T' and corrected ridge angle θ' are 0. In other words, the target value is calculated so that the center of the ridge is located in the center of the width direction of the vehicle body 11 and the longitudinal direction of the vehicle body 11 coincides with the extension direction of the ridge. Of course, the target value P does not have to be 0, and can be set to a value approximating 0 by setting a threshold value. Furthermore, the control amount calculation unit 315 generates a filtered target value Rp based on the target value P. Then, based on the target value P and the filtered target value Rp, it calculates a target turning speed Pω, which is the target speed for turning, and a corrected speed Pv', which is a corrected target moving speed in the longitudinal direction of the work vehicle A.

[0116] At this time, the target turning speed Pω and the corrected speed Pv' are calculated so as to be equal to or less than a traveling speed predetermined by an operator and stored in the memory unit 319. Furthermore, the control amount calculation unit 315 calculates and outputs the target rotation speeds at which the drive wheels 22 arranged on the left and right should rotate, from the calculated target turning speed Pω and corrected speed Pv'. The control amount calculation unit 315 calculates the left moving speed VL' and the right moving speed VR' to be traveled for each of the left and right sides of the vehicle body 11 by performing reverse calculations of the calculations performed by the temporary ridge data generation unit 312. From the left speed VL' and the right speed VR', the control amount calculation unit 315 calculates and outputs the target rotation speeds NL' for the left motor 221L and NR' for the right motor 221R, which are the target rotation speeds.

[0117] The driving control unit 316 will now be described. The travel control unit 316, which receives a command for the target rotation speed of each drive wheel 22 from the control amount calculation unit 315, calculates the corrected rotation speed of each motor 221 so that the rotation speed is the determined speed for each drive wheel 22. Furthermore, the travel control unit 316 adjusts the power frequency f so that the corrected rotation speed for the motor 221 is achieved, and outputs it to each motor 221, causing each motor 221 to rotate at the specified rotation speed. The adjustment of frequency f is calculated based on the phase (also called pole) and target rotation speed, taking into account the rated slip value specific to the motor 221, and a rotation command is sent to the motor 221, causing the drive wheel 22 to rotate. As a result, by the drive wheel 22 rotating at the specified rotation speed, the work vehicle A changes direction with respect to the ridge B, correcting its positional relationship in the width direction and its angle with respect to the ridge direction.

[0118] The work vehicle A controls the rotation speed of each motor 221 to be repeatedly corrected by repeating the series of controls described above within the control device 31. The motors 221, which are controlled in rotation speed, cause the drive wheels 22, which are wheels, to repeatedly change their rotation speed as the vehicle moves. As a result, the vehicle body 11, which is positioned across the ridge B, moves in the direction of the ridge B by adjusting the rotation speed of the drive wheels 22 so that the ridge B is located in the center of the left and right of the vehicle body 11 in a plan view.

[0119] The reverse movement of the work vehicle A will now be described. When work vehicle A moves backward, the direction of travel is switched so that the front side in the direction of travel is the driven wheel 23 side and the rear side in the direction of travel is the drive wheel 22 side. Even when vehicle body 11 is moving backward across ridge B, each sensor is arranged on the front, back, left and right sides of ridge B on either side. Therefore, just as when moving forward, correction values ​​are calculated using distance data measuring the distance between each sensor and ridge B, and the drive wheel 22 is rotated appropriately, allowing vehicle body 11 to move backward along ridge B.

[0120] In the first embodiment, the work vehicle A is described as being positioned across ridges B and running along the ridges B that it has straddled. In the present invention, the work vehicle A can be positioned at the ridge foot B1 between ridges B, and by measuring the distance to the ridges B on both sides using sensors, the vehicle can also be run along the ridges B so that it is positioned exactly midway between the ridges B. In this case, the tips of the first sensor Se1, second sensor Se2, third sensor Se3, and fourth sensor Se4 are directed outward from the vehicle body 11, toward the sides of the ridges B.

[0121] Furthermore, in the first embodiment of the present invention, two sensors are disposed between the drive wheels 22 and the driven wheels 23 in order to optimally travel along the ridges B, but one sensor may be disposed between the drive wheels 22 and the driven wheels 23 (not shown). In this case, the number of sensors to be disposed can be reduced, further simplifying the configuration of the vehicle body 11. Conversely, two or more sensors may be disposed between the drive wheels 22 and the driven wheels 23. In this case, the number of points at which the distance is measured increases, allowing the vehicle body 11 to travel along the ridges B with greater accuracy. The configuration of the machine used in the description is an example and can be modified as appropriate within the scope of the claims. For example, even if the types of motor 221, sensors, etc. are different from those in the embodiment, they are still applicable.

[0122] Work vehicle A is configured and controlled as described above. Even if the distance data S obtained from each sensor is acquired with a time difference, the positional relationship between work vehicle A and ridge B is estimated by calculation from the current driving state of work vehicle A, and distance data S is corrected. In other words, the estimated relative positional relationship is used to calculate as if they were measured simultaneously. This controls motor 221 and drive wheels 22, making it possible to drive along ridge B while maintaining an appropriate positional relationship with ridge B, while simplifying control device 31 and the control content.

[0123] By constantly repeating the control described above while work vehicle A is traveling, work vehicle A can be made to travel along ridge B. Furthermore, even if work vehicle A needs to switch between forward and reverse while traveling along ridge B, it can travel in either direction without significantly changing the content of the rotation control of drive wheels 22. Therefore, while simplifying the control, it is possible for work vehicle A to travel along ridge B, the target, regardless of the direction of travel.

[0124] Furthermore, since the first sensor Se1 to the fourth sensor Se4 are arranged close to the corresponding wheels (drive wheel 22 and driven wheel 23), the risk of the wheels coming into contact with or being stepped on by the ridge B, which is the object to be measured, can be reduced. The configuration described allows the vehicle body 11 to travel along the furrows B without the need for an inertial measurement unit (IMU). In other words, because there is no need to add an inertial measurement unit, which is a type of sensor, the configuration of the control device 31 itself as well as the content of control by the control device 31 is simplified, and the configuration of the work vehicle A is also simplified, allowing the work vehicle A to be configured at low cost. Of course, it goes without saying that an inertial measurement unit can be added to the work vehicle A shown in the embodiment.

[0125] In this invention, the arrangement of the vehicle body 11, motor 221, running unit 21, and sensors is the same as the configuration of the "Work Vehicle" in the previous patent application No. 2024-27348 filed by the applicant of the present application, but compared to the configuration in the same application, the control amount calculation unit 315 constituting the control device 31 further includes a target value generation unit 3151, a PID control unit 3152, a vehicle speed determination unit 3153, and a turning radius regulation unit 3154. By performing the calculation of the invention before calculating the rotational speed (Table 11), even when entering a large curve or when the running part 21 is close to the ridge, it is possible to make the vehicle turn gently and follow the ridge without coming into contact with it. In this embodiment, deceleration control is performed when the positional deviation at a curve or the like during ridge-following travel is greater than a predetermined value. The predetermined value is a value that can change the degree of deceleration depending on whether the positional deviation between the vehicle body 11 and the ridge B is proportional to or causally related to the magnitude of the target value P, and deceleration control is performed according to the positional deviation of the vehicle body 11 by performing a comparison operation with the calculated result.

[0126] Furthermore, in this embodiment, the system comprises a work vehicle A that defines the limit of the amount of turning, a travel method for the work vehicle A, and a travel program for the work vehicle A. That is, it is equipped with running sections 21 arranged on the left and right sides of the lower part of the vehicle body 11, and multiple sensors (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4) arranged at intervals on the lower part of the vehicle body 11 at positions on the front, back, left and right sides of the vehicle body 11, and capable of measuring the distance to the ridge B. Furthermore, the apparatus is provided with a control device 31 that controls the traveling section 21 to travel along the ridge B based on the measured values ​​of the sensors (first sensor Se1, second sensor Se2, third sensor Se3, fourth sensor Se4). Then, as shown in tables [Table 7], [Table 8], [Table 9], [Table 10], etc., vehicle speed determination calculations and other operations are performed in accordance with

[0094] to "0109", and the control device 31 generates a corrected speed Pv' by correcting the arbitrarily set set speed, and calculates the turning restriction angular speed ωlim, which is the limit value at which the running unit 21 can turn without coming into contact with the ridge B, based on the corrected speed Pv' and the turning radius, and controls the running unit 21.

[0127] Furthermore, if the absolute value of the corrected speed Pv' is greater than the absolute value of the turning restriction angular speed ωlim, the absolute value of the corrected speed Pv' and the absolute value of the turning restriction angular speed ωlim are considered to be the same value for calculation. In this embodiment, a work vehicle is provided that can travel along an object regardless of the direction of travel while simplifying the control and control device, and that can control travel while avoiding contact of the caster wheels with ridges using a simple configuration. In addition, by specifying a limit on the amount of turning, it is possible to appropriately control travel along the object. [Explanation of symbols]

[0128] 11 Body 21 Running part 22 Drive wheels 221 Motor 23 Driven wheels 31 Control device 311 Distance data acquisition unit 312 Temporary furrow data generation unit 313 Sensor coordinate correction unit 314 Ridge Data Generation Unit 315 Control amount calculation unit 316 Driving control unit 317 Rotational speed acquisition unit 318 Vehicle Motion Calculation Unit 319 Storage section A Work vehicle B ridge Se1 First sensor Se2 Second sensor Se3 Third sensor Se4 4th sensor

Claims

1. The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A work vehicle characterized by:

2. When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation.

2. The work vehicle according to claim 1.

3. The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A method for traveling a work vehicle.

4. When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation.

4. The method for traveling a work vehicle according to claim 3.

5. The running parts are located on the left and right sides of the lower part of the vehicle body, a plurality of sensors arranged at intervals on the front, rear, left and right sides of the vehicle body under the vehicle body, capable of measuring the distance to the ridges; a control device that controls the traveling unit to travel along the ridges based on the measurement value of the sensor, The control device generates a corrected speed by correcting an arbitrarily set set speed, and calculates a turning restriction angular velocity, which is a limit value at which the traveling unit can turn without contacting the ridge, based on the corrected speed and the turning radius, to control the traveling unit. A working vehicle driving program characterized by:

6. When the absolute value of the corrected speed is greater than the absolute value of the turning restriction angular speed, the absolute value of the corrected speed and the absolute value of the turning restriction angular speed are considered to be equal to each other in the calculation.

6. The work vehicle driving program according to claim 5.

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