Lawn care equipment

Abstract

In a lawn care device comprising a digital camera (7) that can be placed on a mobile unit and directed towards the lawn, a control device and at least one tool (3, 5) that can be steered by the control device and lowered towards the lawn by a motor, the image of the digital camera (7) is fed to an algorithm for performing object detection implemented in the control device, so that when an object is detected, the control device lowers the tool (3, 5) to perform a work step on the object.

Description

Summary of the Invention

[0001] The present invention relates to a lawn care device that can be arranged on a mobile unit. The invention also relates to a lawn mowing robot equipped with such a device, with a mowing mechanism and a traveling drive that functions autonomously.

[0002] To improve the appearance of yards marred by weeds, fallen cones and needles from coniferous trees, or fallen leaves from deciduous trees, to prevent damage to aboveground vegetation due to shade and soil acidification caused by fallen cones and needles, and to prevent damage to the cutting mechanism of lawn mowers by running over cones on the lawn, weeds are removed by hand or eradicated with chemicals, cones, needles, and fallen leaves are removed with a rake or collected by hand, and fallen leaves are blown away with a leaf blower.

[0003] A disadvantage of manual work is the high labor required. A disadvantage of chemical treatment is the possibility of soil contamination, damage to plants and animals, and groundwater contamination. A disadvantage of leaf blowers is the high noise level and the dust swirl that creates fine dust pollution. Known robots and machines for weeding agricultural land do not have a waste collection function. Further disadvantages of known robots and machines for weeding agricultural land are their high cost, heavy weight, and large size, which makes them unsuitable for use in gardens.

[0004] The goal of the present invention is a robot that automatically removes weeds and detects and collects unwanted waste such as cones, needles, fallen leaves, or litter without manual assistance and without the use of chemicals. Furthermore, the present invention aims to at least partially meet the following requirements: - No chemical or exhaust emissions during operation ("green technology"). - No noise or dust is generated. - Protection of the mowing mechanism of lawnmower robots. - Gripping objects of different sizes and shapes with the same gripper, such as cones and needles. - Grasping long objects, such as needles, regardless of their orientation. - Robust functionality. - Safety features. - Compact design. - Low manufacturing costs. - When mounted on a lawnmower robot, it is galvanically isolated from said lawnmower robot or alternatively uses the lawnmower robot's energy supply.

[0005] To solve this problem, the present invention contemplates a lawn care device comprising a digital camera that can be placed on a mobile unit and directed towards the lawn, a control device, and at least one tool that can be steered by the control device and lowered towards the lawn by a motor, wherein images from the digital camera are fed to an algorithm for performing object detection implemented in the control device, so that when the control device detects an object, it lowers the tool to perform a work step on the object.

[0006] At least one tool may be designed for removing weeds and / or for collecting objects to be picked up, such as cones, needles, leaves, or debris, that are on the lawn over which the device travels. For example, there may be a separate tool for removing weeds and a separate tool for collecting objects such as cones, needles, leaves, or debris, the two implements being particularly maneuverable separately from one another to be lowered and perform their respective work steps. Alternatively, the device may only have a single tool designed for removing weeds or for collecting objects such as cones, needles, leaves, or debris that are on the lawn over which the device travels.

[0007] If object detection implemented in the control unit detects a weed in the camera image, the mobile unit or mowing robot is stopped and then commanded to lower the tool to remove the weed.

[0008] If object detection implemented in the control device detects an object to be picked up, such as a cone, needle, fallen leaf, or debris, in the camera image, the mobile unit or mowing robot is stopped and then commanded to lower the tool and pick up the detected object.

[0009] In order to ensure optimal positioning, with the effect that the tool, in its lowered state, is located exactly on or above the detected object, it is provided, according to a further preferred embodiment of the present invention, that the tool, in its lowered state, is located within the detection field of the camera, and that the point of contact of the tool with the grass is assigned a certain image coordinate in the camera image. The positions of the lowered tool and the detection field of the camera are therefore adjusted relative to one another so that the point of contact of the tool is located at a predetermined position within the detection field. This makes it possible to associate the point of contact of the tool with a predetermined image coordinate in the camera image.

[0010] The positioning of the tool relative to the detected object is preferably performed using a travel drive of a mobile unit, such as a lawnmower robot. This allows for a simple design in which the tool itself only needs to be supported by the device so that it can be lowered and raised, without the need for additional degrees of freedom. According to a preferred embodiment of the present invention, the maneuvering of the mobile unit so that the tool is located on or above the detected object after lowering is achieved by an algorithm designed to detect the center point of the detected object, and a control device configured to continuously determine the distance between a fixed image coordinate of the tool's contact point and the center point of the detected object and output control commands to the mobile unit to approach the object until this distance falls below a predetermined limit value. The center point of the detected object can, for example, be detected as the center point of a rectangle or square surrounding the detected object.

[0011] Preferably, the control device is designed as a single-board computer, which on the one hand ensures a simple and low-cost construction and on the other hand ensures sufficient computing power to enable image-based object detection, where a single-board computer is understood to be a computer system in which all electronic components required for operation are integrated on one circuit board.

[0012] To enable reliable object detection with limited computing power and therefore low energy consumption, object detection is preferably performed using deep-learning methods with a convolutional neural network implemented in the control device, in particular on a single-board computer. The weights and bias values of the network's neurons are preferably trained here by transfer learning using more than 2000 images of the object class to be searched for, such as weeds, cones, or needles. For each image examined by the digital camera, the convolutional neural network outputs a matrix that contains, for each detected object, the object class index, the image coordinates of the enclosing rectangle, and the detection probability of the object class.

[0013] If the detection probability of an object exceeds a threshold, for example 50%, the object is classified as detected, any travel process of the mobile unit is stopped, and a command process is started or continued if already in progress. The detected object with the shortest distance to the robot is selected for subsequent command processing to a weeding or grasping process. The center point of a rectangle enclosing the object forms the starting coordinates for command processing.

[0014] As mentioned above, the lowerable tool can be designed as a weeding device for removing weeds. The weeding device can have, for example, a rotary blade or a rotary cutting wire. As soon as a weed is detected within the camera's detection field by object detection, the control device causes the weeding device to be in geometric contact with the ground above the detected weed. The arm extends or lowers together with the weeding device, and the weeding device is activated, causing the weeding device to cut off the weed from its roots. The weeding device is then stopped and retracted again, and travels across the ground again. Most of the roots remain in the soil, but further growth and therefore reproduction of the weed are prevented. After several such cutting processes have been performed, the weeds will no longer take root again and will rot in the soil without further intervention.

[0015] As already mentioned, the lowerable tool can also be designed as a gripper for grasping and picking up objects lying around, such as cones, needles, fallen leaves or rubbish. An advantageous design of the gripper provides for it to be arranged on an arm that can be pivoted about a substantially horizontal axis, which allows the gripper to be lowered and raised again in a simple manner.

[0016] To enable a gripper functional configuration that can reliably grip objects of various shapes, it is preferably provided that the gripper has at least two, in particular three, parallel gripping elements that are movably guided toward and away from one another, the guidance of the gripping elements being preferably configured so that the gripping elements maintain their parallel alignment during the gripping process, so that no normal forces are introduced into the object to be gripped, in contrast to gripping elements that are pivotally, i.e. angularly, movable relative to one another, e.g., like pliers.

[0017] The contact surfaces of the gripping elements may be suitably anodized to increase frictional forces.

[0018] When object detection implemented in the control device, particularly in the single-board computer, detects an object to be picked up, such as a cone, needle, leaf, or debris, the mobile unit is stopped and the lowered gripper is commanded so that its geometric center is above the object. The arm can then be lowered with the gripper open, and the gripper can be closed so that the object is captured. The arm can then be raised, along with the gripper and the grasped object.

[0019] For temporary storage of the collected objects, the device according to a further preferred embodiment further comprises a collection bin arranged below the discharge position of the gripper, whereby as soon as the gripper with the gripped object is raised above the collection bin, the gripper is subsequently opened and the object falls into the collection bin.

[0020] If only the weeding function is required, the arm containing the gripper is omitted. If only the collecting function is required, the arm containing the weeding device is omitted. In an alternative embodiment, the weeding device is not attached to a separate arm, but to a gripper arm or gripper leg.

[0021] The present invention enables a robot-like device for weed removal and waste collection that offers a series of advantages: - No chemicals are released during operation and no emissions are produced ("green technology"), i.e. weeding is purely mechanical and all drives are electrically operated. - Noise and dust generation: the working principle does not rely on suction or blowing effects, so no high-velocity flowing medium is generated anywhere, which can cause noise or the emission of fine dust. - Protection of the mowing mechanism of a mowing robot: when the device is attached to a lawnmower, the camera's image field is realized to cover the mowing area in front of the lawnmower, and the robot detects and removes cones on the lawn before the lawnmower passes through this area. - gripping objects of different sizes and shapes, such as cones and needles, with the same gripper. The implementation of the gripper with radially closing gripping elements or legs provides mutual compensation of the gripping forces. In contrast to grippers implemented on the principle of articulated pliers, there is no need to frictionally compensate the gripping forces. The gripping function is therefore not limited by a friction angle. In the described embodiment of the gripper with radially closing legs, only the weight of the gripped object is absorbed by friction. The gripper grips large objects, such as cones, and small objects, such as needles, in the same radial direction. - gripping long objects, such as needles, regardless of their orientation, i.e., if the long object to be gripped is placed between the radially closing gripping elements or legs of the gripper in the open position, closing the gripper will align the long object between one gripping element and the pair of the remaining two gripping elements, and finally grip the object. Thus, the gripper grips long objects, such as needles, regardless of the direction in which they lie. - Robust function: if a long object to be gripped is placed between the radially closing gripping elements of the gripper in the open position, closing the gripper will center the round object, thus ensuring that the gripping function is performed even when the gripper is positioned incorrectly on the object to be gripped. - Safety features: a continuously running object detection algorithm detects weeds and / or objects to be grasped. As soon as an unknown element appears in the image field, the weeding and grasping process can be stopped immediately. Further protection can be achieved by equipping the robot with commercially available pyroelectric proximity sensors that interrupt the weeding and grasping process when a living organism approaches. - compact design, i.e. when the device is mounted on a lawnmower robot, it does not or only slightly protrudes from the outer periphery of the lawnmower robot when the arms are retracted. The enveloping radius of the open gripper exceeds the maximum possible gripping radius by the radial extension of the gripping elements. - Low manufacturing costs: the possibility of fitting the chassis to a lawnmower robot already present at the user's site or planned for purchase reduces the manufacturing costs of the chassis. In embodiments including an electrical connection to the lawnmower robot, the robot can also share its energy storage (accumulator) and charging infrastructure, eliminating the need to implement them on the robot. By coupling the movement of the gripping elements in the gripper with the above-mentioned trajectory of the weeding device, the described movement results in a motorized movement axis and the associated minimization of manufacturing costs. The trajectory of the weeding device is preferably arranged at a right angle to the horizontal, so that friction torques only need to be overcome for the horizontal component of the movement. Weight only needs to be overcome for the vertical component of the movement. This allows for a compact, low-cost actuator with a low rotational torque for the weeding device arm. - When attached to a robotic lawnmower, it allows for galvanically isolated operation from the robotic lawnmower. In this implementation, the robot is commanded via WLAN. No physical intervention inside the robotic lawnmower is required. This prevents any associated degradation of the robotic lawnmower's value and possible losses in warranty claims.

[0022] Further features and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention, without limiting the scope of protection, with reference to the attached drawings. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 shows a perspective view of a robot. [Figure 2]FIG. 1 shows a perspective view of a robot. [Figure 3] FIG. 10 shows a perspective view of the robot with the arms of the weeding device folded. [Figure 4] FIG. 1 shows a perspective view of the robot with the gripper arms folded. [Figure 5] A side view of the robot is shown. [Figure 6] FIG. [Figure 7] FIG. 2 is a perspective view of the gripper in an open position. [Figure 8] FIG. 2 is a perspective view of the gripper in a closed position. [Figure 9] FIG. 10 is a detailed perspective view of the gripper in an open position. [Figure 10] 1 is an add-on module for a lawnmower in an embodiment as a robot for weeding, as a retrofit of an existing lawnmower robot. [Figure 11] 1 is an add-on module for a lawnmower in an embodiment as a robot for weeding, as a retrofit of an existing lawnmower robot. [Figure 12] This is a lawnmower robot with an additional module added. [Figure 13] A lawnmower robot with an add-on module attached, with the weed-eating arm extended. DETAILED DESCRIPTION OF THE INVENTION

[0024] The robot consists of a base frame 1, an arm 2 which is motorized and extendable about an inclined axis and which includes a weeding device 3, and a further arm 4 which is motorized and which includes a gripper 5.

[0025] A base frame 1 is mounted to a lawnmower robot 6. In an alternative embodiment, the base frame is realized with its own running gear as a mobile platform.

[0026] A camera 7 takes images of the area 8 in front of the robot in the direction of travel, which images are continuously evaluated by an object detector with a frequency of at least 3 Hz.

[0027] The camera 7 is connected to the base frame 1, to which the arm 2 of the weeding device 3 is also hinged. The geometric contact point of the extended weeding device with the ground is assigned a fixed image coordinate in the camera image, which forms the target coordinate for processing the weeding command. The arm 4 of the gripper 5 is also hinged to the base frame 1. The geometric center point of the lowered gripper is likewise assigned a fixed image coordinate in the camera image, which forms the target coordinate for processing the gripping command.

[0028] To command the robot to move toward the target coordinate, the output coordinate continuously determined by the object detection is used as a feedback signal to control the robot's movement. According to the distance between the starting coordinate and the target coordinate, a driving torque is applied to the left and right wheel drives of the lawnmower robot 6, i.e., a driving torque is applied in the same direction as the robot's moving direction to shorten the distance from the starting coordinate to the target coordinate, and a driving torque is applied in the opposite direction normal to the robot's moving direction to shorten the distance from the starting coordinate to the target coordinate. When the starting coordinate is within a tolerance radius of approximately 5 mm around the target coordinate, the target is deemed to have been reached, and the corresponding arm is lowered to weed or grasp, and the weeding or grasping process is carried out.

[0029] If no other objects are detected in the camera image, the previously stopped driving process of the lawnmower robot 6 continues, thus the lawnmower robot 6 continues mowing, searching for a charging station, or turning.

[0030] The single-board computer is connected to the Internet via WLAN or, in an alternative embodiment, via a mobile data connection such as LTE. The user preferentially controls the robot via a browser or app on a mobile phone, tablet, or PC. Data exchange with the lawnmower robot, including commands to the wheel drives for steering towards target coordinates, is also performed via WLAN.

[0031] In an alternative embodiment, there is a cable connection to the mowing robot for data exchange via a data line and / or for power supply to the robot by an accumulator on the mowing robot, in which case the accumulator 10 for automatic energy supply to the robot is omitted if the accumulator on the mowing robot is used jointly by the robot.

[0032] Motor control electronics mounted in the same housing 9 serve to operate the drives for the two arms 2 and 4, as well as the drives for the weeding device 3 and gripper 5, and, in an alternative embodiment, the running gear if the base frame is not attached to the lawnmower robot, and are supplied with energy from an accumulator 10 on the robot, similar to a single-board computer.

[0033] An arm 2 is attached to the base frame 1, at the end of which there is a weeding device 3. The arm is rotatable about an inclined axis 11 connected to an electric drive 12. The position of the axis 11 is selected so that when the arm 2 is extended, the weeding device 3 leaves the base frame 1 and descends to the ground in the same movement, where the weeding device 3 is seen by the image field 8 of the camera 7.

[0034] The weeding device 3 consists of a rotary blade 13 driven by an electric motor 30. In an alternative embodiment, the weeding device comprises a cutting wire instead of said rotary blade 13.

[0035] A further arm 4 is attached to the base frame 1. This arm 4 is supported so as to be rotatable on two sides about an axis 14. In an alternative embodiment, this arm 4 is realised so as to be rotatable on one side about the axis 14. A gripper 5 is attached to this arm 4. Said rotation is realised by an electric drive 15 using a tow rope 16. The position of the axis 14 is chosen so that the rotation of the arm 4 moves the gripper 5 from a position above the base frame 1 to a position in front of the robot, where it is captured by the image field 8 of the camera 7.

[0036] A collection container 17 is attached to the base frame 1 below the upper position of the gripper 5. Any objects released from the gripper fall into this collection container 17.

[0037] In a further embodiment, the collection container 17 is hinged to the base frame 1 at a rotation axis 18 that runs horizontally, perpendicular to the direction of travel, near the upper edge of the collection container. A disposal station that is connected to a charging station or that is realized independently of the charging station is provided with a connecting link 19 that is arranged below the level of this rotation axis. When entering the disposal station or the charging station towards the connecting link 19, the collection container 17 rotates in the direction indicated by the arrow 20 due to a collision with the connecting link 19, and in the process, the contents of the collection container 17 are emptied. In this process, the arm 4 including the gripper 5 is folded away from the range of movement of the collection container to prevent a collision from occurring.

[0038] The gripper 5 consists of three similar radially interacting legs, each consisting of a connecting piece 21 and a gripping element 22. Each leg is rotatably arranged by means of a ball bearing pair 24 about an axis of rotation 23 offset with respect to said gripping element 22. Rotation of the legs about the axis of rotation 23 causes the gripping elements 22 to move along a circular path. The axes of rotation of the three legs are arranged at approximately the same distance from each other on a common pitch circle, so that the movement of the gripping elements 22 caused by the rotation of the legs opens and closes the three gripping elements 22 relative to one another. An electric drive 25 is arranged in the center of the pitch circle.

[0039] The transmission of rotational motion between the electric drive 25 and the three legs is achieved by a push rod 26. In the illustrated embodiment, the push rod 26 is made up of two parts. The part of the push rod that is rotatably connected to the drive is internally threaded, and the part of the push rod that is rotatably connected to the legs is externally threaded. Twisting the push rod components relative to one another changes the length of the push rod, thus making it possible to adjust the contact points of the three legs when the gripper is closed. In an alternative embodiment, the transmission of rotational motion between the drive and the three legs is achieved by a gear transmission, in which the legs are provided with gears or gear segments that mesh with a central sun gear between the leg gears or with a ring gear surrounding the leg gears. In this embodiment, assembling the gears in the corresponding angular positions adjusts the contact points between the legs when the gripper is closed.

[0040] In the illustrated embodiment, the drive is centrally located. In an alternative embodiment, one of the three legs is directly driven by the drive. In this alternative embodiment, the transmission of rotational motion between the directly driven leg and the other two legs is achieved by the described push rod or the described gear transmission.

[0041] The legs are composed of two parts. The leg connecting piece 21, which is rotatably connected to the push rod 26, has flat surfaces 27 on which the gripping elements 22 are clamped by screw fastening in holes 28. The sliding of the gripping elements 22 along the flat surfaces 27 allows the parallelism of the gripping elements 22 of the three legs to be adjusted for precise closing along the contact line. The gripping elements 22 have an L-shaped cross section, which provides high bending stiffness and a position of their shear center in the direction of the clamping force, preventing distortion when applying the gripping force. The gripping elements 22 are anodized, which provides a high coefficient of friction between the gripping elements and the object being gripped and makes them highly wear-resistant.

[0042] In one embodiment as a robot for weed removal, an add-on module 29 is attached to an existing lawn mowing robot 6. Inside this add-on module 29, a camera 7 and an arm 2 for lowering the weeding device 3 are provided. A single-board computer and motor control electronics are housed in a housing 9. The add-on module is connected to the lawn mowing robot 6 by a frame 1, which in this embodiment is substantially more compact.

Claims

1. 1. A lawn care device comprising: a digital camera (7) that can be placed on a mobile unit and directed towards the lawn, a control device, and at least one tool (3, 5) that can be steered by the control device and can be lowered towards the lawn by a motor, the images from the digital camera (7) are fed to an algorithm implemented in the control device for performing object detection, so that when the control device detects an object, it lowers the tool (3, 5) to perform a work step on the object; Equipment for lawn care.

2. 2. The device according to claim 1, wherein the tool (3, 5) is placed in a lowered position within the detection field of the camera (7), and the contact points of the tool (3, 5) with the grass are assigned certain image coordinates in the camera image.

3. 3. The device according to claim 2, characterized in that the algorithm is designed to detect the center point of a detected object, and the control device is configured for continuously determining the distance between the constant image coordinates of the contact points of the tool (3, 5) and the center point of the detected object, to output control commands to the mobile unit to approach the object until said distance falls below a predetermined limit value.

4. 4. Device according to claim 1, 2 or 3, characterized in that the control device is designed as a single-board computer.

5. 4. Device according to any one of claims 1 to 3, characterized in that the tool is designed as a weeding device (3).

6. 6. A device according to claim 5, characterized in that the weeding device (3) comprises one or more rotary blades (13) or rotary cutting wires.

7. 6. A device according to claim 5, characterized in that the weeding device (3) is arranged on an arm (2) which is pivotable about an axis (11) which goes from an oblique position to a horizontal position relative to the vertical.

8. 4. Device according to any one of claims 1 to 3, characterized in that the tool is designed as a gripper (5).

9. 9. Device according to claim 8, characterized in that the gripper (5) is arranged on an arm (4) which is pivotable about a substantially horizontal axis.

10. 9. The device according to claim 8, characterized in that the gripper (5) has at least two, in particular three, parallel gripping elements (22), which are movably guided towards and away from one another.

11. 11. The device according to claim 10, characterized in that the movement of the gripping elements (22) proceeds along respective arcs, the pivot axes (23) forming the centers of each of the arcs being arranged evenly along the circle and parallel to one another.

12. 12. The device according to claim 11, characterized in that a drive member (25) is provided which is rotatably driven by a motor around the axis of the circle, said drive member (25) being drivingly connected to each of said gripping elements (22) and therefore driving each of said gripping elements (22) along its respective arc.

13. 11. Device according to claim 10, characterized in that the contact surfaces of the gripping elements (22) are anodized.

14. 9. Apparatus according to claim 8, characterized in that the apparatus further comprises a collection container (17) arranged below the discharge position of the gripper (5).

15. 15. Device according to claim 14, characterized in that the collecting container (17) is hinged on a rotation axis (18) extending horizontally, perpendicular to the direction of travel, in the region of the upper edge of the collecting container (17), so that the collecting container (17) can be tilted and emptied by moving towards a connecting link (19) positioned below the rotation axis (18).

16. 4. Apparatus according to any one of claims 1 to 3, characterized in that an electric motor drive is provided for lowering and raising said at least one tool (3, 5).

17. 4. Device according to any one of claims 1 to 3, characterized in that the device is designed as an integral component or as a retrofit module for attachment to a mowing robot (6) as a mobile unit.

18. A lawnmower robot (6) equipped with a mowing mechanism and an autonomously functioning traveling drive, characterized in that the lawnmower robot (6) is equipped with a device according to any one of claims 1 to 3.

19. 19. A lawnmower robot according to claim 18, characterized in that the digital camera (7) is directed towards the lawn in front of the mowing mechanism in the direction of travel.

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