Lawn mower, lawn mowing system and drive control method

Abstract

The present invention relates to a mower, a mowing system, and a drive control method. The mower includes drive devices respectively provided on right and left sides of the mower and configured to be independently driven, and one or more processors configured to: estimate a gradient of a slope on a travel path; and drive the drive devices on the right and left sides with different drive forces based on the estimated gradient, so that the mower does not slide down a slope when the mower travels in a direction across the slope.

Description

Technical Field

[0001] The invention relates to a lawn mower, a lawn mowing system and a driving control method. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2018-174707 (JP 2018-174707 A) discloses a lawn mower that mows grass while traveling along an intended working slope automatically or by remote control. Summary of the Invention

[0003] A lawn mower mowing on a slope as described above may slide down the slope depending on the gradient of the slope and become unable to travel in the traveling direction, thereby deviating from a predetermined traveling path.

[0004] In view of the above facts, the present invention provides a lawn mower, a lawn mowing system, and a drive control method for the lawn mower, which are capable of traveling in a traveling direction without deviating from a predetermined traveling path.

[0005] A lawn mower according to a first aspect of the present invention includes: drive devices, which are respectively provided on the right and left sides of the lawn mower and are configured to be driven independently; and one or more processors, which are configured to: estimate the gradient of a slope on a travel path; and drive the drive devices with different drive forces on the right and left sides based on the estimated gradient, so that when the lawn mower travels in a direction across the slope, the lawn mower does not slide down the slope.

[0006] In the lawn mower according to the first aspect of the present invention, the drive devices (drive units) provided on the right and left sides may be driven independently. The one or more processors may estimate the gradient of a slope on the travel path.

[0007] In the lawn mower according to the first aspect of the present invention, the one or more processors drive the drive units with different drive forces on the right and left sides based on the estimated slope, so as to prevent the lawn mower from sliding down the slope when traveling in a direction across the slope. Therefore, even if the lawn mower's travel path has a slope, the lawn mower's travel direction is corrected by driving the right and left drive units with different drive forces based on the slope when traveling in a direction across the slope. As a result, the lawn mower can be prevented from sliding down the slope, allowing the lawn mower to travel in the direction of travel without deviating from the predetermined travel path.

[0008] In the above aspect, the one or more processors can be configured to set one of the driving forces of the driving device located on the lower side of the slope to be greater than another driving force of the driving force of the driving device located on the upper side of the slope when the lawn mower travels in a direction across the slope.

[0009] In the above aspect, when the lawn mower is traveling in a direction across a slope, the one or more processors set the driving force of the drive unit located on the lower side of the slope to be greater than the driving force of the drive unit located on the upper side of the slope. Therefore, a torque for rotating the main body of the lawn mower toward the upper side of the slope can be generated, and the direction of travel of the lawn mower can be corrected.

[0010] In the above aspect, the one or more processors may be configured to drive the driving device with different driving forces on the right and left sides when the estimated slope is greater than a predetermined slope.

[0011] In the above aspect, when the estimated slope is greater than the preset slope, the one or more processors drive the right drive unit and the left drive unit with different driving forces. Therefore, the direction of travel of the lawn mower can be effectively corrected on a slope with a slope that may cause the lawn mower to slide down the slope.

[0012] In the above aspect, each of the driving device on the right side and the driving device on the left side may include a driving motor; and the one or more processors may be configured to drive the driving device with different driving forces on the right side and the left side by differently controlling the driving motor of the driving device on the right side and the driving motor of the driving device on the left side.

[0013] In the above aspect, each of the drive unit on the right side and the drive unit on the left side includes a drive motor. Therefore, the drive of the drive unit on the right side and the drive of the drive unit on the left side can be controlled differently by the corresponding drive motors. In the lawn mower according to the above aspect, the one or more processors drive the drive motor of the drive unit on the right side and the drive motor of the drive unit on the left side through different controls. Therefore, the right drive unit and the left drive unit can be driven with different driving forces. By driving the drive motors of the drive units by different controls on the right and left sides, the right drive unit and the left drive unit can be easily driven with different driving forces.

[0014] In the above aspect, the pair of drive devices, a drive device on the right side and a drive device on the left side, may include: a single drive motor; and a differential gear, wherein the differential gear is configured to distribute the output from the single drive motor to the drive device on the right side and the drive device on the left side; and the one or more processors may be configured to: drive the drive devices on the right side and the left side with different driving forces by causing a difference in the number of rotations per unit time between the rotating body of the drive device on the right side and the rotating body of the drive device on the left side, wherein the rotating body of the drive device on the right side and the rotating body of the drive device on the left side are rotated by the output transmitted from the differential gear.

[0015] In the above aspect, the one or more processors cause a difference in the number of rotations per unit time between the rotating body of the drive unit on the right side and the rotating body of the drive unit on the left side, the rotating body being rotated by the output transmitted from the differential gear. Thus, the drive unit can be driven with different driving forces on the right and left sides. By using the differential gear, the drive unit can be driven with different driving forces on the right and left sides even with a single drive motor.

[0016] In the above aspect, the lawn mower may include a three-axis acceleration sensor. The one or more processors may be configured to estimate the slope based on acceleration information acquired by the three-axis acceleration sensor.

[0017] In the above aspect, a three-axis acceleration sensor is provided, and thus information about the acceleration of the lawn mower in three directions can be obtained. The one or more processors estimate the slope of the slope based on the acceleration information obtained by the three-axis acceleration sensor. Therefore, the slope can be estimated based on the acceleration information obtained by the three-axis acceleration sensor (i.e., the lateral component of the gravitational acceleration applied to the body of the lawn mower). As a result, the one or more processors can drive the drive unit with different driving forces on the right and left sides based on the slope of the current slope. As a result, the lawn mower can travel along the travel path with greater accuracy.

[0018] In the above aspect, the one or more processors may be configured to estimate the slope of the unit area in the captured image based on height information of the travel path based on pre-acquired point cloud data in the captured image including the travel path.

[0019] In the above aspect, the one or more processors estimate the slope's gradient based on the height information of the travel path based on pre-acquired point cloud data for the preset travel path. Thus, the gradient of the slope along the travel path can be estimated in advance. As a result, the lawn mower's travel direction can be corrected before the main body of the lawn mower slides down the slope. This prevents the main body of the lawn mower from sliding down the slope, allowing the lawn mower to continue traveling in the desired direction without deviating from the predetermined travel path.

[0020] In the above aspect, the lawn mower may include a three-axis acceleration sensor. The one or more processors may be configured to: perform a first estimation of a slope based on acceleration information acquired by the three-axis acceleration sensor; perform a second estimation of a slope of a unit area in a captured image based on height information of a travel path based on previously acquired point cloud data in the captured image including the travel path; and switch between using the slope estimated by the first estimation and the slope estimated by the second estimation based on a predetermined condition.

[0021] In the above aspect, a three-axis acceleration sensor is provided, and thus information about the acceleration of the lawn mower in three directions can be obtained. The one or more processors can perform a first estimation, which estimates the gradient of the slope based on the acceleration information obtained by the three-axis acceleration sensor. Therefore, the gradient can be estimated based on the acceleration information obtained by the three-axis acceleration sensor (i.e., the lateral component of the gravitational acceleration applied to the body of the lawn mower). As a result, the one or more processors can drive the right drive unit and the left drive unit with different driving forces based on the gradient of the slope currently being traveled. Therefore, the lawn mower can travel along the travel path with higher accuracy.

[0022] In the above aspect, the one or more processors estimate the slope's gradient based on the height information of the travel path based on pre-acquired point cloud data for the preset travel path. Thus, a second estimation can be performed to pre-estimate the gradient of the slope on the travel path. As a result, the lawn mower's travel direction can be corrected before the main body of the lawn mower slides down the slope. This prevents the main body of the lawn mower from sliding down the slope, allowing the lawn mower to continue traveling in the direction of travel without deviating from the predetermined travel path.

[0023] In the above aspect, the one or more processors perform a first estimation and a second estimation, and based on a predetermined condition, switch between the slope estimated by the first estimation and the slope estimated by the second estimation for use. Thus, for example, if the one or more processors are performing drive control based on the slope estimated by the first estimation and a deviation occurs in the acceleration information acquired by the triaxial acceleration sensor, the one or more processors can switch drive control to drive control based on the slope estimated by the second estimation. As a result, the lawn mower can continue to travel in the direction of travel without deviating from the predetermined travel path.

[0024] A lawn mowing system according to a second aspect of the present invention includes an external device configured to estimate a slope along a travel path and output information regarding the estimated slope, and a lawn mower provided separately from the external device. The lawn mower includes drive devices, each provided on the right and left sides of the lawn mower and configured to be driven independently; and one or more processors configured to receive the output information and, based on the received information, drive the drive devices with different drive forces on the right and left sides to prevent the lawn mower from sliding down the slope when traveling in a direction across the slope.

[0025] In the mowing system according to the second aspect of the present invention, the external device may estimate the gradient of the slope on the travel path. The external device may also output information about the estimated gradient.

[0026] In the lawn mowing system according to the second aspect of the present invention, the lawn mower is provided separately from the external device. Therefore, the lawn mower can receive information about the slope estimated by the external device. Therefore, the lawn mower does not need to have a slope estimation function. The lawn mower can independently drive the drive units provided on the right and left sides.

[0027] In particular, in the lawn mower of the lawn mowing system according to the second aspect of the present invention, the one or more processors drive the drive unit with different driving forces on the right and left sides based on the received slope information, so as to prevent the lawn mower from sliding down the slope when traveling in a direction that crosses the slope. Therefore, even if the lawn mower's travel path has a slope, the lawn mower's travel direction is corrected by driving the drive unit with different driving forces on the right and left sides based on the slope. As a result, the lawn mower can be prevented from sliding down the slope, allowing the lawn mower to travel in the intended direction without deviating from the intended path.

[0028] In a drive control method for a lawn mower according to a third aspect of the present invention, the lawn mower includes drive devices disposed on the right and left sides of the lawn mower, respectively, and configured to be driven independently. The drive control method includes estimating the gradient of a slope on a travel path based on acceleration information obtained by a three-axis acceleration sensor on the travel path or height information of the travel path based on point cloud data in a captured image previously acquired for the travel path; and driving the drive devices with different drive forces on the right and left sides based on the estimated gradient, so that the lawn mower does not slide down the slope when traveling in a direction across the slope.

[0029] In the drive control method for a lawn mower according to the third aspect of the present invention, the gradient of a slope on the travel path can be estimated based on acceleration information output by a three-axis acceleration sensor on the travel path or height information of the travel path based on point cloud data in a captured image acquired in advance for the travel path.

[0030] In a drive control method for a lawn mower according to a third aspect of the present invention, in a lawn mower including drive units provided on the right and left sides and driven independently, the drive units can be driven with different drive forces on the right and left sides based on an estimated slope so that the lawn mower does not slide down the slope when the lawn mower travels in a direction crossing the slope.

[0031] In a drive control method for a lawn mower according to a third aspect of the present invention, the drive unit is driven with different drive forces on the right and left sides based on an estimated slope to prevent the lawn mower from sliding down the slope when traveling in a direction that crosses the slope. Therefore, even if the lawn mower's travel path has a slope, the lawn mower's travel direction is corrected by driving the drive unit with different drive forces on the right and left sides based on the slope. As a result, the lawn mower can be prevented from sliding down the slope, allowing the lawn mower to travel in the direction of travel without deviating from the predetermined travel path.

[0032] As described above, the lawn mower, the lawn mowing system, and the drive control method for the lawn mower according to the present invention achieve the excellent effect that the lawn mower can travel in the travel direction without deviating from a predetermined travel path. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements, and wherein:

[0034] Figure 1 is a perspective view schematically illustrating the structure of a lawn mower according to a first embodiment of the present invention;

[0035] Figure 2 yes Figure 1 A bottom-up perspective view of a lawn mower in [Image file].

[0036] Figure 3 It is a schematic diagram Figure 1 A perspective view of the structure of a cutting blade unit of a lawn mower;

[0037] Figure 4 is a block diagram showing a hardware configuration of a lawn mower according to a first embodiment of the present invention;

[0038] Figure 5 is a block diagram showing a functional configuration of a lawn mower according to a first embodiment of the present invention;

[0039] Figure 6 is an explanatory diagram illustrating a slope estimation method of a lawn mower according to a modification of the first embodiment of the present invention;

[0040] Figure 7 is an explanatory diagram illustrating travel of the lawn mower according to the first embodiment of the present invention on a slope;

[0041] Figure 8 is an explanatory diagram illustrating drive control of a lawn mower on a slope according to a first embodiment of the present invention;

[0042] Figure 9 is a flowchart showing a series of processes in the lawn mower according to the first embodiment of the present invention;

[0043] Figure 10 is a flowchart illustrating a slope estimation process of a lawn mower according to a first embodiment of the present invention;

[0044] Figure 11 is a flowchart showing a series of processes in a lawn mower according to a modification of the first embodiment of the present invention;

[0045] Figure 12 is a flowchart showing a slope estimation process of a lawn mower according to a modification of the first embodiment of the present invention;

[0046] Figure 13 is a flowchart showing a series of processes in a lawn mower according to a modification of the second embodiment of the present invention;

[0047] Figure 14 is a block diagram showing a hardware configuration of a lawn mower according to a third embodiment of the present invention; and

[0048] Figure 15 is a block diagram showing a hardware configuration of a mowing system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0049] First embodiment

[0050] A lawn mower 10 according to a first embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, arrow UP indicates the upper side in the vertical direction of the vehicle, and arrow FR indicates the front side in the longitudinal direction of the vehicle. Arrow LH indicates the left side in the width direction of the vehicle, and arrow RH indicates the right side in the width direction of the vehicle. In the following description, the vertical direction and the longitudinal direction refer to "up" and "down" in the vertical direction of the vehicle and "front" and "rear" in the longitudinal direction of the vehicle, and the lateral direction refers to "right" and "left" in the width direction of the vehicle.

[0051] Structure of the lawn mower 10

[0052] The lawn mower 10 according to the first embodiment is a self-propelled lawn mower and is used to mow grass on ridges of paddy fields or farmlands, for example. Figure 1 As shown in the figure, the lawn mower 10 includes a body 12, a crawler unit 14 serving as a drive unit (drive device), a motor controller 16, a battery device 18, a control device 20, a drive motor 22, a camera unit 24, a global positioning system or global positioning satellite (GPS) device 26, a sensor unit 27, an outer cover 28 and a cutting blade unit 30.

[0053] like Figure 1 and Figure 2 As shown in FIG, the body 12 is made of a substantially rectangular plate material, and various devices are placed on its upper surface. The body 12 has a lower cover 12A that covers the inner side of four track units 14, described later, in the vehicle width direction. The lower cover 12A is made of plate material and extends downward in a substantially rectangular shape from both ends of the body 12 in the vehicle width direction at positions corresponding to the four track units 14. In this embodiment, the body 12 and the lower cover 12A are shown as an integrated whole, but they may be formed separately.

[0054] The body 12 has a cutting blade cover 13 between two lower covers 12A provided on the right side and between two lower covers 12A provided on the left side, which covers the cutting blade 36 of the cutting blade unit 30 described later. Each cutting blade cover 13 is made of a plate material and is connected to the lower covers 12A of the two crawler units 14 at both ends in the front-rear direction of the vehicle. The body 12, the lower covers 12A and the cutting blade covers 13 are made of, for example, a metal material such as steel or aluminum or a fiber-reinforced plastic material.

[0055] The cutting blade cover 13 includes a central portion 13A, two inclined portions 13B, and an upper portion 13C. The central portion 13A has a rectangular shape and protrudes outward in the width direction of the vehicle relative to the lower cover 12A. The two inclined portions 13B are arranged at the two ends of the central portion 13A in the front-to-rear direction of the vehicle and extend obliquely from the two ends of the central portion 13A in the front-to-rear direction of the vehicle toward the lower cover 12A. The upper portion 13C has a substantially trapezoidal shape, and its four sides are connected to the body 12, the central portion 13A, and the two inclined portions 13B. In this embodiment, for example, the cutting blade cover 13, the body 12, and the lower cover 12A are formed separately, but may be integrated together. The cutting blade cover 13 prevents foreign matter from entering the cutting blade 36 from the lateral sides (i.e., the right and left sides of the lawn mower 10) and also prevents cut grass from scattering to the lateral sides of the lawn mower 10.

[0056] The track units 14 are arranged in the front-to-rear direction on both the right and left sides. The lawn mower 10 of this embodiment includes four track units 14. Each track unit 14 includes a rotating body 14A and a track 14B. The rotating body 14A is a substantially right-angled triangular prism and rotates around an axis extending in the width direction of the vehicle. The track 14B is a rubber member that covers the outer peripheral surface of the rotating body 14A around its axis and has a belt-like shape. The outer surface of the track 14B has concave and convex shapes (not shown) to maintain the travel performance even when the conditions of the travel surface are unstable. The shaft (not shown) of the rotating body 14A is connected to the motor shaft (not shown) of the drive motor 22 and is rotated by the drive motor 22. In this embodiment, the two front track units 14 and the rear track units 14 on the left side in the width direction of the vehicle can be referred to as the "left track unit 14L", and the two front track units 14 and the rear track units 14 on the right side in the width direction of the vehicle can be referred to as the "right track unit 14R".

[0057] The motor controller 16 controls the driving of the drive motors 22 and the cutting blade motor 32 described later. As described later, the lawn mower 10 of this embodiment includes four drive motors 22 and two cutting blade motors 32. For example, the lawn mower 10 of this embodiment includes a total of six motor controllers 16A to 16F, namely, four motor controllers 16A to 16D that respectively control the driving of the four drive motors 22 and two motor controllers 16E and 16F that respectively control the driving of the two cutting blade motors 32.

[0058] The motor controllers 16A to 16D that control the driving of the drive motor 22 are electrically connected to the drive motor 22 and the control device 20 (see FIG. Figure 4). The motor controllers 16A to 16D control the driving of the rotating body 14A (i.e., the crawler unit 14) connected to the driving motor 22. The motor controllers 16E and 16F that control the driving of the cutting blade motor 32 are electrically connected to the cutting blade motor 32 and the control device 20 (see Figure 4 The motor controllers 16E and 16F control driving of a cutter blade 36 described later that is coupled to the cutter blade motor 32. A method for controlling the crawler unit 14 by the motor controllers 16A to 16D will be described in detail later.

[0059] Each battery device 18 serves as a driving source for the drive motor 22 and is, for example, a rechargeable direct current (DC) power source having a rated voltage of 18V and a rated capacity of 6.0Ah. The battery device 18 includes a secondary battery such as a lithium-ion secondary battery or a nickel metal hydride battery, and a capacitor such as a double-layer capacitor may also be used. The lawn mower 10 of this embodiment includes, for example, four battery devices 18. The four battery devices 18 supply power to the electronic devices (such as the drive motor 22 and the cutting blade motor 32) mounted on the lawn mower 10.

[0060] The control device 20 controls the driving of the lawn mower 10 as a whole, and is arranged on the upper side of the interior of the outer cover 28. The control device 20 will be described in detail later.

[0061] Four drive motors 22 are provided in the lawn mower 10 of this embodiment and are, for example, DC brushless motors. The four drive motors 22 are connected to the four crawler units 14 and are driven by commands from the motor controllers 16A to 16D, respectively.

[0062] The camera units 24 are cameras capable of imaging the surrounding environment of the lawn mower 10, and are provided on the front and rear sides of the upper outer surface of the outer cover 28 in the lawn mower 10 of this embodiment. Each of the camera units 24 provided on the front and rear sides includes a three-dimensional (3D) camera 24A and a Raspberry Pi camera 24B.

[0063] The GPS device 26 includes an antenna (not shown) that receives signals from an artificial satellite (GPS satellite) (not shown), and is capable of measuring the current position of the lawn mower 10 .

[0064] The sensor unit 27 includes a three-axis acceleration sensor and outputs gravitational acceleration in the lateral direction (horizontal direction: x direction), the front-back direction (horizontal direction: y direction), and the vertical direction (vertical direction: z direction). In this embodiment, the sensor unit 27 outputs these gravitational accelerations as acceleration information.

[0065] The outer cover 28 is a box-shaped housing having an open bottom, and covers the body 12 from above.

[0066] The cutting blade unit 30 has a structure for mowing grass. Figure 3 As shown in FIG, the cutting blade unit 30 includes a rectangular plate-shaped base portion 31 arranged on the upper surface of the body 12. The base portion 31 has a height adjustment structure (not shown) that can adjust the height in the vertical direction relative to the body 12. The height adjustment structure may be, for example, manual or automatic, and may be a known structure.

[0067] The cutter blade motor 32 is installed at a predetermined distance in the lateral direction on the upper surface of the base portion 31. In the present embodiment, the cutter blade motor 32 is, for example, a DC brushless motor.

[0068] Each of the two cutting blade motors 32 includes a motor shaft 34 inserted through an insertion hole (not shown) of the base portion 31. Cutting blades 36 are rotatably fixed to lower end portions of the two motor shafts 34, respectively.

[0069] The cutting blade 36 includes a disc portion 37 rotatably fixed to the motor shaft 34, and four rectangular cutting edges 38 fixed to the disc portion 37 so as to protrude outward in four directions from the outer periphery of the disc portion 37. The right and left cutting blades 36 are arranged at positions slightly offset in the vertical direction (height direction) so that their cutting edges 38 do not interfere with each other. The cutting blades 36 are rotationally driven by the cutting blade motor 32 to cut grass.

[0070] In this embodiment, the height of the base portion 31 is adjusted vertically by the height adjustment structure described above, thereby adjusting the height position of the cutting blade 36. In this embodiment, the height is adjusted to position the cutting edge 38 at a height of 50 millimeters (mm) from the ground, for example. For example, in addition to the height of 50 mm from the ground, the height of the cutting edge 38 can be adjusted to multiple levels, such as 80 mm and 100 mm. Therefore, mowing can be performed at any of these heights.

[0071] In the present embodiment, the control device 20 controls the travel of the lawn mower 10 based on pieces of data acquired by the camera unit 24 , the GPS device 26 , and the sensor unit 27 , and a travel path stored in a storage device 20D described later.

[0072] Hardware configuration of Lawn Mower 10

[0073] Next, the control device 20 will be described in detail. Figure 4As shown in FIG, the control device 20 mounted on the lawn mower 10 includes a central processing unit (CPU) 20A as an example of a processor, a read-only memory (ROM) 20B, a random access memory (RAM) 20C, a storage device 20D, a communication interface (communication I / F) 20E, and an input / output interface (input / output I / F) 20F. These components are communicably connected to each other via a bus 20G.

[0074] The CPU 20A is a central processing unit that executes various programs and controls various components. Specifically, the CPU 20A reads programs from the ROM 20B or storage device 20D and executes them using the RAM 20C as a work area. Based on the programs stored in the ROM 20B or storage device 20D, the CPU 20A controls each component and performs various operations.

[0075] The ROM 20B stores various programs and various types of data. The RAM 20C temporarily stores programs and data as a workspace. The storage device 20D includes a hard disk drive (HDD) or a solid-state drive (SSD) and stores various programs, including an operating system, and various types of data, including map data. The storage device 20D also stores preset travel routes. In this embodiment, the ROM 20B or storage device 20D stores programs for executing various functions, various types of data, and the like.

[0076] The communication I / F 20E is an interface that allows the lawn mower 10 to communicate with a server (not shown) and other devices, and uses standards such as Ethernet (registered trademark), Long Term Evolution (LTE), Fiber Distributed Data Interface (FDDI), and Wi-Fi (registered trademark).

[0077] The input / output I / F 20F is an interface that allows the control device 20 to communicate with various devices mounted on the lawn mower 10. The control device 20 is communicably connected to each device described later via the input / output I / F 20F. These devices can be directly connected to the bus 20G.

[0078] Specifically, the input / output I / F 20F is connected to the motor controllers 16A to 16D, the motor controllers 16E and 16F, the camera unit 24 , the GPS device 26 , the sensor unit 27 , and the like.

[0079] The motor controllers 16A to 16D output control signals to the drive motor 22 based on command signals input from the control device 20 to control, for example, the number of rotations, the rotation speed, and the rotation direction of the drive motor 22. In this embodiment, the control device 20 and the motor controllers 16A to 16D can change the travel direction of the lawn mower 10 by independently controlling the number of rotations, the rotation speed, and the rotation direction of the drive motor 22.

[0080] The motor controllers 16E and 16F output control signals to the cutting blade motor 32 based on the command signal input from the control device 20 to control, for example, the number of rotations, the rotation speed, and the rotation direction of the cutting blade motor 32. In this embodiment, the control device 20 and the motor controllers 16E and 16F can change the mowing conditions of the lawn mower 10 by independently controlling the number of rotations, the rotation speed, and the rotation direction of the cutting blade motor 32.

[0081] The camera unit 24 is a camera that images the surroundings of the lawn mower 10 and temporarily stores captured images of objects around the lawn mower 10 in the storage device 20D.

[0082] The GPS device 26 temporarily stores the measured position information of the lawn mower 10 in the storage device 20D, and updates the position information of the lawn mower 10 at predetermined time intervals.

[0083] The sensor unit 27 is a device for detecting the inclination of the lawn mower 10 (i.e., the slope of the travel path). The gravitational acceleration in the lateral direction (x-direction), the front-back direction (y-direction), and the vertical direction (z-direction) output by the sensor unit 27 is temporarily stored in the storage device 20D. The gravitational acceleration data stored in the storage device 20D is noise-removed by applying a predetermined filter to the gravitational acceleration data output from the sensor unit 27.

[0084] Next, we will refer to Figure 5 The functional configuration of the control device 20 is described. The control device 20 functions as a set of a drive control unit 202, a cutting blade control unit 204, and a gradient estimation unit 206 by the CPU 20A reading an execution program stored in the ROM 20B and executing the program.

[0085] The drive control unit 202 inputs control signals to the motor controllers 16A to 16D based on the travel path and map data stored in the storage device 20D, the image captured by the camera unit 24, and the position information of the lawn mower 10 acquired by the GPS device 26. The drive control unit 202 controls the drive motor 22 via the motor controllers 16A to 16D to cause the lawn mower 10 to travel along the travel path. When an object approaching the lawn mower 10 is detected in the image captured by the camera unit 24, the drive control unit 202 controls the drive motor 22 via the motor controllers 16A to 16D to temporarily stop the lawn mower 10.

[0086] When the drive control unit 202 starts the travel of the lawn mower 10, the cutting blade control unit 204 inputs, for example, a preset number of revolutions, a preset rotation speed, and a preset rotation direction of the cutting blade motor 32 to the motor controllers 16E and 16F, and controls the number of revolutions, rotation speed, and rotation direction of the cutting blade motor 32 via the motor controllers 16E and 16F. When an object approaching the lawn mower 10 is detected in the image captured by the camera unit 24 or the cutting blade motor 32 is overloaded, the cutting blade control unit 204 controls the cutting blade motor 32 via the motor controllers 16E and 16F to temporarily stop the rotation of the cutting blade 36.

[0087] The gradient estimation unit 206 estimates the gradient of a slope on a predetermined travel path (ie, the travel path stored in the storage device 20D) based on the gravity acceleration data output by the sensor unit 27 (specifically, the gravity acceleration data stored in the storage device 20D).

[0088] like Figure 6 As shown in , when the direction of travel of the lawn mower 10 is transverse to (substantially perpendicular to) the inclination direction of the slope 40, the slope estimation unit 206 estimates the slope of the slope 40, that is, the inclination angle θ. In this embodiment, the slope estimation unit 206 estimates the slope based on, for example, the component g(x) of the gravitational acceleration g in the lateral direction (x direction). Specifically, the value of g(x) increases as the inclination angle θ increases. Therefore, derived data showing the relationship between the component g(x) of the gravitational acceleration g in the lateral direction (x direction) and the inclination angle θ is pre-acquired and stored in the storage device 20D. The slope estimation unit 206 then derives the inclination angle θ based on the derived data of the value of the component g(x) of the gravitational acceleration g in the lateral direction (x direction) acquired from the storage device 20D.

[0089] The drive control unit 202 drives the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the slope (ie, the value of the inclination angle θ) estimated by the slope estimation unit 206. Figure 7When the lawn mower 10 travels on the slope 40 along the travel path shown in FIG, the gravity component g(x) in the lateral direction (x direction) of the lawn mower 10 exists as a force pulling the lawn mower 10 downward on the slope 40. This pulling force may increase depending on the gradient of the slope 40. Therefore, the lawn mower 10 may slide down the slope 40 and become unable to travel in the predetermined travel direction D. In this embodiment, the right crawler unit 14R and the left crawler unit 14L are driven with different driving forces based on the gradient of the slope 40.

[0090] Specifically, in Figure 7 , the drive control unit 202 controls the drive motor 22 via the motor controllers 16A to 16D so that the drive force of the left crawler unit 14L located on the lower side of the slope 40 is greater than the drive force of the right crawler unit 14R located on the upper side of the slope 40. The drive control unit 202 performs control so that the difference in drive force between the right crawler unit 14R and the left crawler unit 14L increases as the slope (i.e., the inclination angle θ) increases.

[0091] like Figure 8 As shown in FIG, the driving force of the left crawler unit 14L located on the lower side of the slope 40 is greater than the driving force of the right crawler unit 14R located on the upper side of the slope 40, thereby generating a moment for rotating the lawn mower 10 clockwise. Therefore, it is possible to correct the traveling direction of the lawn mower 10. In this embodiment, for example, when the slope of the slope 40 (i.e., the inclination angle θ) is greater than 25 degrees and equal to or less than 45 degrees, the drive control unit 202 controls the right crawler unit 14R and the left crawler unit 14L to drive with different driving forces.

[0092] The upper and lower limits of the inclination angle θ can be changed by the user. For example, the lower limit can be changed to 20 degrees or 30 degrees. For example, the upper limit can be changed to 38 degrees, 50 degrees, or 58 degrees. The upper and lower limits of the inclination angle θ can be changed based on, for example, the friction coefficient (i.e., the degree of concavity) of the surface of the crawler track 14B of each crawler track unit 14.

[0093] Drive control method

[0094] In the following, we will mainly refer to Figure 9 and Figure 10 The flowchart of the driving control method of the lawn mower 10 is used to describe the process of a series of processes. Figure 9 In step S10 , the drive control unit 202 of the lawn mower 10 according to the first embodiment first controls the driving of the drive motor 22 to start the travel of the lawn mower 10 , and the cutting blade control unit 204 controls the driving of the cutting blade motor 32 to start mowing by the lawn mower 10 .

[0095] In step S11, the gradient estimation unit 206 estimates the gradient of the slope 40 on the travel path. Figure 10 In step S20 , the gradient estimation unit 206 acquires gravity acceleration data, that is, acceleration information, output from the sensor unit 27 and stored in the storage device 20D.

[0096] In step S21, based on the derived data stored in the storage device 20D, the slope estimation unit 206 derives the slope of the slope 40 on the travel path, that is, the inclination angle θ, according to the value of the component g(x) of the gravitational acceleration g in the lateral direction (x direction) in the acceleration information obtained from the storage device.

[0097] Come back for reference Figure 9 , the drive control unit 202 determines in step S12 whether the slope (inclination angle) of the current travel area is equal to or less than 45 degrees. If the slope is not equal to or less than 45 degrees (i.e., the slope is greater than 45 degrees) (step S12; No), the drive control unit 202 determines that the lawn mower 10 is having difficulty traveling and stops the lawn mower 10 to end mowing. If the slope is equal to or less than 45 degrees in step S12 (step S12; Yes), the drive control unit 202 determines in step S13 whether the slope (inclination angle) of the current travel area is greater than 25 degrees.

[0098] If the slope is greater than 25 degrees (step S13: Yes), the drive control unit 202 drives the right crawler unit 14R and the left crawler unit 14L with different driving forces in step S14 to cause the lawn mower 10 to travel. That is, when the lawn mower 10 travels in a straight-forward direction (travel direction) on a flat surface, the driving forces of the right crawler unit 14R and the left crawler unit 14L are substantially the same. When the lawn mower 10 travels in a travel direction that crosses the inclination direction of the slope 40, the lawn mower 10 travels by driving the right crawler unit 14R and the left crawler unit 14L with different driving forces.

[0099] Specifically, the drive control unit 202 controls the number of rotations or the rotation speed of the drive motor 22 via the motor controllers 16A to 16D so that the driving force of the left crawler unit 14L located on the lower side of the slope 40 having the gradient is greater than the driving force of the right crawler unit 14R located on the upper side of the slope 40. The drive control unit 202 controls the drive motor 22 so that the difference in driving force between the right crawler unit 14R and the left crawler unit 14L increases as the gradient (i.e., the inclination angle θ) increases.

[0100] If the slope is equal to or less than 25 degrees in step S13 (step S13: No), the drive control unit 202 recognizes the travel path as a flat surface and causes the lawn mower 10 to travel normally in step S15. The term "normal travel" not only means that the lawn mower 10 travels with the same driving force from the right crawler unit 14R and the left crawler unit 14L, but also means that the lawn mower 10 travels along the travel path on the plane in the travel direction. In other words, when the travel direction changes, the drive control unit 202 can cause the lawn mower 10 to travel with different driving forces from the right crawler unit 14R and the left crawler unit 14L.

[0101] In step S16, the drive control unit 202 determines whether mowing is complete. Specifically, the drive control unit 202 determines whether the lawn mower 10 has finished traveling along the predetermined travel path. If mowing is not yet complete (step S16: No), the CPU 20A advances the process to step S11 and executes the processes of step S11 and subsequent steps. If mowing is complete (step S16: Yes), the drive control unit 202 stops the lawn mower 10 to complete mowing.

[0102] Operation and Effects of the First Embodiment

[0103] Next, the operation and effects of the first embodiment will be described.

[0104] The lawn mower 10 of the first embodiment includes four crawler units 14 (a right crawler unit 14R (right front crawler unit 14 and right rear crawler unit 14) and a left crawler unit 14L (left front crawler unit 14 and left rear crawler unit 14)) provided at the front and rear portions on the right and left sides and driven independently. The lawn mower 10 also includes a gradient estimation unit 206 that estimates the gradient of a slope 40 on a preset travel path, and a drive control unit 202 that drives the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the gradient estimated by the gradient estimation unit 206.

[0105] Therefore, the right and left crawler units 14R and 14L, respectively, can be driven independently. The slope estimation unit 206 estimates the slope 40 on the travel path. The drive control unit 202 drives the drive units on the right and left sides with different drive forces based on the slope estimated by the slope estimation unit 206, so that the lawn mower 10 does not slide down the slope 40 when traveling across the slope 40. Therefore, even if the travel path of the lawn mower 10 has a slope, the right and left crawler units 14R and 14L are driven with different drive forces based on the slope to correct the direction of travel of the lawn mower 10 when traveling across the slope. As a result, the lawn mower 10 is prevented from sliding down the slope 40, allowing the lawn mower 10 to travel in the intended travel direction without deviating from the intended travel path.

[0106] When the lawn mower 10 of the first embodiment travels in a direction crossing the slope 40, the drive control unit 202 sets the driving force of the crawler unit 14 located on the lower side of the slope 40 to be greater than the driving force of the crawler unit 14 located on the upper side of the slope 40. Therefore, a moment that rotates the body of the lawn mower 10 toward the upper side of the slope 40 can be generated, and thus the traveling direction of the lawn mower 10 can be corrected.

[0107] In the lawn mower 10 of the first embodiment, when the slope estimated by the slope estimation unit 206 is greater than 25 degrees, the drive control unit 202 drives the right crawler unit 14R and the left crawler unit 14L with different drive forces. Therefore, the travel direction of the lawn mower 10 can be effectively corrected on the slope 40 having a slope at which the lawn mower 10 may slide down the slope.

[0108] In the lawn mower 10 of the first embodiment, the right track unit 14R and the left track unit 14L each include a drive motor 22. Therefore, the lawn mower 10 can perform different drive controls on the right and left track units 14R and 14L through their respective drive motors 22. Because the drive control unit 202 drives the drive motor 22 of the right and left track units 14R and 14L through different controls, the right and left track units 14R and 14L can be driven with different drive forces. By driving the drive motors 22 of the track units 14 through different controls on the right and left sides, the right and left track units 14 can be easily driven with different drive forces.

[0109] The lawn mower 10 of the first embodiment includes a sensor unit 27 comprising a triaxial acceleration sensor. Therefore, it is possible to obtain information regarding the acceleration of the lawn mower 10 in three directions. The slope estimation unit 206 estimates the slope of the slope 40 based on the acceleration information obtained by the sensor unit 27. Therefore, the slope can be estimated based on the acceleration information obtained by the sensor unit 27 (i.e., the lateral component of the gravitational acceleration applied to the main body of the lawn mower 10). As a result, the drive control unit 202 can drive the right and left crawler units 14 with different drive forces based on the slope 40 currently being traveled. Consequently, the lawn mower 10 can travel along the travel path with greater accuracy.

[0110] The drive control method for the lawn mower 10 of the first embodiment includes estimating the gradient of slope 40 based on acceleration information acquired by the sensor unit 27 along the travel path; and driving the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the estimated gradient so that the lawn mower 10 does not slide down slope 40 when traveling in a direction that traverses slope 40. Therefore, even if the travel path of the lawn mower 10 has a gradient, the travel direction of the lawn mower 10 is corrected by driving the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the gradient when the lawn mower 10 travels in a direction that traverses slope 40. As a result, the lawn mower 10 can be prevented from sliding down slope 40. Therefore, the lawn mower 10 can travel in the travel direction without deviating from the predetermined travel path.

[0111] variants

[0112] In the lawn mower 10 of the first embodiment, the gradient estimation unit 206 estimates the gradient of the slope 40 by using the acceleration information output by the sensor unit 27, but the present invention is not limited thereto. Figures 1 to 5 ), the slope estimation unit 206A estimates the slope of the unit area. The "unit area" can be appropriately changed according to the size of the lawn mower 10A, the accuracy of the point cloud data described later, and the like.

[0113] The slope estimation method performed by the slope estimation unit 206A will be described. Figure 11 and Figure 12 The flowchart of FIG. 1 is used to describe a series of processes of the driving control method of the lawn mower 10A.

[0114] like Figure 11As shown in FIG, in a lawn mower 10A as a modification of the lawn mower 10 according to the first embodiment, before starting mowing in step S31, the slope estimation unit 206A performs a slope estimation process in step S30. That is, the slope estimation unit 206A estimates the slope of a unit area on the travel path in advance.

[0115] exist Figure 12 In step S40, slope estimation unit 206A first acquires a plurality of aerial images captured by a drone (not shown) from different locations, showing an area including the predetermined travel path. In step S41, slope estimation unit 206A converts the acquired aerial images into three-dimensional data. Specifically, a conversion tool such as Metashape (registered trademark) is used.

[0116] In step S42, the slope estimation unit 206A obtains point cloud data of the area including the travel path from the three-dimensional data obtained by conversion. Examples of point cloud data include point cloud data for each area of ​​50 mm in the longitudinal and lateral directions (y and x directions). Point cloud data is three-dimensional data represented by orthogonal coordinates (x, y, z).

[0117] In step S43, the slope estimation unit 206A obtains the height information of the predetermined travel path from the point cloud data. In this modification, for example, the width M of the "unit area" in the longitudinal direction and the lateral direction is set as follows. In the value of 50 mm × n (n is an integer), the distance H between the center of the crawler 14B in the lateral direction of the right crawler unit 14R closest to the lawn mower 10 and the center of the crawler 14B in the lateral direction of the left crawler unit 14L (see Figure 8 ) is defined as the width M. The inclination direction of the slope 40 is assumed to be the longitudinal direction of the unit area. Specifically, the slope estimation unit 206A acquires the coordinates of each width M in the z direction in the point cloud data.

[0118] In step S44, the slope estimation unit 206A calculates the slope (i.e., the inclination angle θ) of the unit area, which is an area having a width M in the inclination direction and a width M in a direction orthogonal to the inclination direction. Specifically, the inclination angle θ is calculated based on Expression (1). The calculated inclination angle θ is stored in the storage device 20D in association with the orthogonal coordinates (x, y, z).

[0119] Tilt angle θ = tan -1 ((|z2-z1|) / M)×180 / π...(1)

[0120] In this expression, π is 3.14.

[0121] Come back for reference Figure 11When the slope estimation unit 206A estimates the slope of the unit area on the travel path, in step S31, the drive control unit 202 controls the driving of the drive motor 22 to start the travel of the lawn mower 10A, and the cutting blade control unit 204 controls the driving of the cutting blade motor 32 to start mowing the lawn mower 10A. Figure 11 The process of steps S32 to S36 is the same as Figure 9 The processes of steps S12 to S16 are the same, and thus a detailed description thereof will be omitted.

[0122] Operation and Effect of Modification of First Embodiment

[0123] Next, the operation and effects of the modification of the first embodiment will be described.

[0124] In a lawn mower 10A, a variation of the lawn mower 10 of the first embodiment, the slope estimation unit 206A estimates the slope of the slope 40 based on the height information of the travel path in point cloud data previously acquired for a preset travel path. Therefore, the slope of the slope 40 along the travel path can be estimated in advance. As a result, the travel direction of the lawn mower 10A can be corrected before the main body of the lawn mower 10A slides down the slope 40. Therefore, the lawn mower 10A can be prevented from sliding down the slope 40, allowing the lawn mower 10A to travel in the direction of travel without deviating from the predetermined travel path.

[0125] The drive control method for the lawn mower 10A of the first embodiment includes estimating the gradient of the slope 40 based on the height information of the travel path in point cloud data from a previously acquired captured image (aerial image) of the travel path. Therefore, the gradient of the slope 40 along the travel path can be estimated in advance. As a result, the travel direction of the lawn mower 10A can be corrected before the main body of the lawn mower 10A slides down the slope 40. Therefore, the lawn mower 10A can be prevented from sliding down the slope 40, allowing the lawn mower 10A to travel in the intended direction without deviating from the intended travel path.

[0126] Slope estimation unit 206A in this modification uses a conversion tool such as Metashape (registered trademark), but the present invention is not limited to this. For example, altitude information can be acquired using known trigonometric methods. Slope estimation unit 206A acquires aerial images captured by a drone, but the present invention is not limited to this. For example, aerial images can be acquired by downloading from an external site. Slope estimation unit 206A can also acquire orthophoto images containing three-dimensional data in advance.

[0127] Second embodiment

[0128] The lawn mower 10B of the second embodiment (see Figures 1 to 5) includes a slope estimation unit 206B that is different from the slope estimation unit of the lawn mower 10 of the first embodiment and the lawn mower 10A of the modification. When the slope of the slope 40 on the travel path is estimated in advance as in the above modification, the geographical features may change due to landslides on the slope 40 caused by rain, for example, depending on the time when the aerial image is captured. When the slope of the slope 40 currently being traveled is estimated as in the above-mentioned first embodiment, the acceleration information acquired by the sensor unit 27 may deviate depending on the conditions of the ground, such as bumps and pits on the slope 40.

[0129] In the lawn mower 10B of the second embodiment, the slope estimation unit 206B performs both the first estimation performed by the slope estimation unit 206 of the first embodiment and the second estimation performed by the slope estimation unit 206A of the modification. The slope estimated by the first estimation and the slope estimated by the second estimation are switched for use based on a predetermined condition.

[0130] In the second embodiment, for example, the lawn mower 10B first uses the slope estimated by the first estimation, and then uses the slope estimated by the second estimation when a predetermined condition is satisfied. For example, the roll angle R of the lawn mower 10B, that is, the inclination of the lawn mower 10B, is obtained by a known method, and the aforementioned "condition" is satisfied when the difference between the roll angle R and the estimated inclination angle θ is equal to or greater than 20 degrees.

[0131] The slope estimation method performed by the slope estimation unit 206B will be described. Figure 13 The flowchart of FIG. 1 is used to describe a series of processes of the driving control method of the lawn mower 10B.

[0132] like Figure 13 As shown in FIG. 1 , in the lawn mower 10B according to the second embodiment, before mowing starts in step S51, the slope estimation unit 206B performs a second estimation, i.e., a slope estimation process 2, in step S50. That is, the slope estimation unit 206B estimates the slope of the unit area based on the height information of the travel path in the point cloud data acquired in advance for the travel path. The second slope estimation process 2 in step S50 is the same as the slope estimation process 2 in FIG. Figure 11 The slope estimating process 2 in step S30 is the same as that in step S30, and therefore a detailed description thereof will be omitted.

[0133] In step S51 , the drive control unit 202 controls the driving of the drive motor 22 to start the travel of the lawn mower 10B, and the cutting blade control unit 204 controls the driving of the cutting blade motor 32 to start mowing by the lawn mower 10B.

[0134] In step S52, the slope estimation unit 206B performs the first estimation, that is, the slope estimation process 1. That is, the slope estimation unit 206B estimates the slope based on the gravity acceleration data (that is, acceleration information) output from the sensor unit 27 and stored in the storage device 20D. The slope estimation process 1 in step S52 is the same as the slope estimation process 1 in step S52. Figure 9 The slope estimating process 1 in step S11 is the same as that in step S11, and therefore a detailed description thereof will be omitted.

[0135] In step S53, the slope estimation unit 206B determines whether the angle difference between the roll angle R of the lawn mower 10B and the inclination angle θ estimated in step S52 is equal to or greater than 20 degrees. If the angle difference is equal to or greater than 20 degrees (step S53: Yes), the slope estimation unit 206B determines that there is a possibility that the inclination angle θ estimated in step S52 is deviated. In step S54, the slope estimation unit 206B uses the slope (inclination angle θ) estimated in step S50 (second estimation).

[0136] When the determination is made in step S53 that the angle difference is less than 20 degrees (step S53; No), the slope estimation unit 206B determines that there is no deviation in the inclination angle θ estimated in step S52. In step S55, the slope estimation unit 206B uses the slope (inclination angle θ) estimated in step S52 (first estimation). The processes of steps S56 to S60 are the same as those of steps S57 to S60. Figure 9 The processes of steps S12 to S16 are the same, and thus a detailed description thereof will be omitted.

[0137] Operation and Effects of the Second Embodiment

[0138] Next, the operation and effects of the second embodiment will be described.

[0139] The lawn mower 10B of the second embodiment includes a sensor unit 27. Therefore, it can acquire information regarding the acceleration of the lawn mower 10B in three directions. The slope estimation unit 206B can perform a first estimation of the slope's gradient based on the acceleration information acquired by the sensor unit 27. Therefore, the gradient can be estimated based on the acceleration information acquired by the sensor unit 27 (i.e., the lateral component of the gravitational acceleration applied to the main body of the lawn mower 10B). As a result, the drive control unit 202 can drive the right track unit 14R and the left track unit 14L with different drive forces based on the gradient of the slope 40 currently being traveled. Consequently, the lawn mower can travel along the travel path with greater accuracy.

[0140] In the lawn mower 10B of the second embodiment, the slope estimation unit 206B estimates the slope of the slope 40 based on the height information of the preset travel path in the point cloud data previously acquired for the travel path. Thus, a second estimation can be performed to pre-estimate the slope of the slope 40 on the travel path. As a result, the travel direction of the lawn mower 10B can be corrected before the main body of the lawn mower 10B slides down the slope. This prevents the main body of the lawn mower 10B from sliding down the slope, allowing the lawn mower 10B to continue traveling in the direction of travel without deviating from the predetermined travel path.

[0141] In the lawn mower 10B of the second embodiment, the slope estimation unit 206B performs both a first estimation and a second estimation, and the drive control unit 202 switches between the slope estimated by the first estimation and the slope estimated by the second estimation based on a predetermined condition. Therefore, for example, if a discrepancy occurs in the acceleration information acquired by the sensor unit 207 while the drive control unit 202 is executing drive control based on the slope estimated by the first estimation, the drive control unit 202 can switch the drive control to drive control based on the slope estimated by the second estimation. As a result, the lawn mower 10B can travel in the direction of travel without deviating from the predetermined travel path.

[0142] Third embodiment

[0143] While the lawn mower 10 of the first embodiment and the modified lawn mower 10A each include four motor controllers 16 and four drive motors 22, the lawn mower 10C of the third embodiment includes two motor controllers 16 and two drive motors 22. Figure 14 In addition, the lawn mower 10C includes two differential gears 50 .

[0144] At the front of the lawn mower 10C, one drive motor 22 and one differential gear 50 are provided for the right track unit 14R and the left track unit 14L, and at the rear of the lawn mower 10C, one drive motor 22 and one differential gear 50 are provided for the right track unit 14R and the left track unit 14L. The differential gear 50 is a device that transmits power to the rotating body 14A of the right track unit 14R and the rotating body 14A of the left track unit 14L while providing a difference in the number of rotations per unit time, and a known structure can be used.

[0145] Each of the front differential gear 50 and the rear differential gear 50 is connected to a shaft (not shown) of the rotating body 14A of the right track unit 14R and a shaft (not shown) of the rotating body 14A of the left track unit 14L, which are arranged to extend in the lateral direction. A motor shaft (not shown) of the drive motor 22 is directly or indirectly connected to the differential gear 50 to transmit power from the drive motor 22. Therefore, in each of the front differential gear 50 and the rear differential gear 50, the output from one drive motor 22 can be distributed to the right track unit 14R and the left track unit 14L.

[0146] The drive control unit 202 of the lawn mower 10C of the third embodiment drives the right track unit 14R and the left track unit 14L with different drive forces by causing a difference in the number of rotations per unit time between the rotating body 14A of the right track unit 14R and the rotating body 14A of the left track unit 14L rotated by the output transmitted from the differential gear 50.

[0147] Operation and Effects of the Third Embodiment

[0148] Next, the operation and effects of the third embodiment will be described.

[0149] The drive control unit 202 of the lawn mower 10C of the third embodiment drives the right crawler unit 14R and the left crawler unit 14L with different driving forces at each of the front and rear parts by causing a difference in the number of rotations per unit time between the rotating body 14A of the right crawler unit 14R and the rotating body 14A of the left crawler unit 14L, which are rotated by the output transmitted from the differential gear 50. By using the differential gear 50, the right crawler unit 14R and the left crawler unit 14L can be driven with different driving forces at each of the front and rear parts even with one drive motor 22.

[0150] Fourth embodiment

[0151] Next, a mowing system 100 according to a fourth embodiment will be described. Figure 15 As shown in FIG, a lawn mower system 100 includes a lawn mower 10D and an external device 60. The lawn mower 10D has a configuration in which the slope estimation unit 206A is omitted from the lawn mower 10A of the first embodiment. The same configuration as that of the lawn mower 10A of the first embodiment can be used as the other configurations, and therefore, a detailed description thereof will be omitted. In the lawn mower 10D, the communication I / F 20E corresponds to the second communication unit.

[0152] The external device 60 includes a gradient estimating unit 602 , a travel path setting unit 604 , a storage unit 606 , a communication I / F 608 , and the like.

[0153] The slope estimating unit 602 has the same function as the slope estimating unit 206A in the lawn mower 10A of the modification of the first embodiment.

[0154] The travel path setting unit 604 sets a travel path along which the lawn mower 10D travels, and stores the set travel path and map data of an area including the set travel path in association with each other in the storage unit 606 .

[0155] Storage unit 606 stores the travel path preset by travel path setting unit 604. Storage unit 606 also stores the slope of a unit area on the travel path estimated by slope estimation unit 602, in association with the orthogonal coordinates (x, y, z). In this embodiment, storage unit 606 stores programs for executing various functions, various types of data, and the like.

[0156] The communication I / F 608 is an interface for communicating with the lawn mower 10D and uses standards such as Ethernet (registered trademark), LTE, FDDI, and Wi-Fi (registered trademark). The communication I / F 608 corresponds to the first communication unit and, specifically, outputs information about the slope estimated by the slope estimation unit 602 to the lawn mower 10D.

[0157] The driving control method of the lawn mower 10D in the lawn mowing system 100 of this embodiment is similar to Figure 11 The driving control method shown in is basically the same. The only difference in the lawn mower 10D in the lawn mowing system 100 is that the slope estimation unit 602 provided in the external device 60 performs Figure 11 In the mowing system 100 of the present embodiment, when traveling while mowing, the mower 10D refers to the slope of the unit area stored in the storage unit 606 of the external device 60 via the communication I / F 608 .

[0158] Operation and Effects of the Fourth Embodiment

[0159] Next, the operation and effects of the fourth embodiment will be described.

[0160] In the mowing system 100 according to the fourth embodiment, the external device 60 includes a slope estimation unit 602. Therefore, the external device 60 can estimate the slope of the slope 40 on the travel path. The external device 60 also includes a communication interface 608. Therefore, information about the slope estimated by the slope estimation unit 602 can be output via the communication interface 20E of the mower 10D.

[0161] In the mowing system 100 according to the fourth embodiment, the mower 10D includes a communication I / F 20E as a second communication unit, and is provided separately from the external device 60 including the slope estimation unit 602. Therefore, the mower 10D can receive information about the slope estimated by the slope estimation unit 602 installed on the external device 60 via the communication I / F 20E. Therefore, the mower 10D does not need to have the function of the slope estimation unit. In the mower 10D, the right crawler unit 14R and the left crawler unit 14L provided on the right and left sides can be driven independently.

[0162] In the mowing system 100 according to the fourth embodiment, the drive control unit 202 of the mower 10D drives the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the slope information received via the communication I / F 20E, so that the mower 10D does not slide down the slope 40 when the mower 10D travels in a direction that traverses the slope 40. Therefore, even if the travel path of the mower 10D has a slope, the travel direction of the mower 10D is corrected by driving the right crawler unit 14R and the left crawler unit 14L with different drive forces based on the slope when the mower 10D travels in a direction that traverses the slope 40. As a result, the mower 10D can be prevented from sliding down the slope 40, allowing the mower 10D to travel in the travel direction without deviating from the predetermined travel path.

[0163] In the lawn mowers 10 and 10B of the first and second embodiments, the sensor unit 27 includes a three-axis acceleration sensor, but the present invention is not limited thereto. The sensor unit 27 may include, for example, three acceleration sensors each detecting acceleration along one of three different axes, or a gyro sensor may be used if the inclination of the lawn mower 10 can be detected. Therefore, the sensor unit 27 may have any configuration.

[0164] In the lawn mowers 10 and 10B of the first and second embodiments, derived data showing the relationship between the component g(x) of the gravitational acceleration g in the lateral direction (x direction) and the inclination angle θ is acquired in advance, and the inclination angle θ is derived from the value of g(x) output from the sensor unit 27 based on this derived data. However, the method for estimating the inclination angle θ (i.e., the slope) is not limited to this. For example, the inclination angle θ can be derived based on a known expression or can be appropriately changed.

[0165] In the above embodiment, when the drive control unit 202 starts the lawn mower 10, the cutting blade control unit 204 starts controlling the driving of the cutting blade motor 32. However, the present invention is not limited to this. The cutting blade control unit 204 may start controlling the driving of the cutting blade motor 32 while the lawn mower 10 is moving or before the lawn mower 10 starts moving.

[0166] In each crawler unit 14 of the above embodiment, the rotating body 14A is a substantially right-angled triangular column, but the present invention is not limited thereto. For example, the rotating body 14A may have an elliptical or circular shape, or may be appropriately changed.

[0167] In the above embodiment, the lawn mower 10 is four-wheel drive, but the present invention is not limited thereto. The lawn mower 10 may be two-wheel drive.

[0168] In the above embodiment, the crawler unit 14 is used as the drive unit, but the present invention is not limited to this. The drive unit may be, for example, a wheel. The drive unit of the lawn mower of the present invention is not limited to four drive units. The lawn mower may have a structure in which one drive unit is provided on the right side and another drive unit is provided on the left side.

[0169] In the embodiment, various processors other than the CPU may execute the Figure 4 and Figure 14 Each process executed when the CPU 20A shown in the figure reads and executes the software (program). In this case, examples of the processor include a programmable logic device (PLD) whose circuit configuration can be changed after production, such as a field programmable gate array (FPGA) and a dedicated circuit as a processor (the processor has a circuit configuration specifically designed to execute a specific process), such as an application-specific integrated circuit (ASIC). Each process can be executed by one of these different processors, or by a combination of two or more processors of the same type or different types (for example, a combination of multiple FPGAs or a combination of a CPU and an FPGA, etc.). The hardware structure of each of the various processors is more specifically a circuit in which circuit elements such as semiconductor elements are combined.

[0170] Each program described in the embodiments can be provided by recording on a recording medium such as a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM) or a universal serial bus (USB) memory. In addition, the program can be downloaded from an external device via a network.

[0171] The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various modifications other than the above embodiment can be made without departing from the scope of the present invention.

Claims

1. A lawn mower, characterized in that include: drive devices, the drive devices being respectively provided on the right and left sides of the lawn mower, and the drive devices on the right and left sides of the lawn mower being configured to be driven independently; as well as One or more processors configured to: estimating the slope of a slope on the path of travel; and driving the driving device with different driving forces on the right side and the left side based on the estimated slope so that the lawn mower does not slide down the slope when the lawn mower travels in a direction crossing the slope, wherein the one or more processors are configured to: when the lawn mower travels in a direction crossing the slope, set the driving force of the driving device located on the lower side of the slope to be greater than the driving force of the driving device located on the upper side of the slope; The lawn mower further comprises a three-axis acceleration sensor, wherein the one or more processors are configured to: performing a first estimation, the first estimation being used to estimate the slope based on acceleration information acquired by the triaxial acceleration sensor; performing a second estimation for estimating a slope of a unit area in the captured image based on height information of the travel path based on point cloud data in the captured image including the travel path acquired in advance, The lawn mower first uses the slope estimated by the first estimation, and when the angle difference between the acquired roll angle of the lawn mower and the slope estimated by the first estimation is equal to or greater than 20 degrees, switches to use the slope estimated by the second estimation.

2. The lawn mower according to claim 1, wherein: The one or more processors are configured to drive the driving device with different driving forces on the right side and the left side when the estimated slope is greater than a predetermined slope.

3. The lawn mower according to claim 1 or 2, characterized in that: each of the drive means on the right side and the drive means on the left side includes a drive motor; and The one or more processors are configured to drive the driving device with different driving forces on the right and left sides by differently controlling a driving motor of the driving device on the right side and a driving motor of the driving device on the left side.

4. The lawn mower according to claim 1 or 2, characterized in that: The pair of drive means, the drive means on the right side and the drive means on the left side, comprises: a single drive motor; and a differential gear configured to distribute output from the single drive motor to the drive device on the right side and the drive device on the left side; and The one or more processors are configured to drive the drive device with different driving forces on the right side and the left side by causing a difference in the number of rotations per unit time between the rotating body of the drive device on the right side and the rotating body of the drive device on the left side, wherein the rotating body of the drive device on the right side and the rotating body of the drive device on the left side are rotated by the output transmitted from the differential gear.

5. A drive control method for a lawn mower, the lawn mower comprising drive devices, the drive devices being respectively provided on the right and left sides of the lawn mower, and the drive devices on the right and left sides of the lawn mower being configured to be driven independently, the drive control method being characterized by comprising: estimating the slope of a slope on a travel path; as well as driving the driving device with different driving forces on the right side and the left side based on the estimated slope so that the lawn mower does not slide down the slope when the lawn mower travels in a direction crossing the slope, wherein, when the lawn mower travels in a direction crossing the slope, the driving force of the driving device located on the lower side of the slope is set to be greater than the driving force of the driving device located on the upper side of the slope, The lawn mower further includes a three-axis acceleration sensor, wherein the drive control method further includes: performing a first estimation, the first estimation being used to estimate the slope based on acceleration information acquired by the triaxial acceleration sensor; performing a second estimation for estimating a slope of a unit area in the captured image based on height information of the travel path based on point cloud data in the captured image including the travel path acquired in advance, The lawn mower first uses the slope estimated by the first estimation, and when the angle difference between the acquired roll angle of the lawn mower and the slope estimated by the first estimation is equal to or greater than 20 degrees, switches to use the slope estimated by the second estimation.

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