Mowing Robot

Abstract

The present application provides a lawn mowing robot, comprising a frame, a first wheel group and a second wheel group. The first wheel group and the second wheel group are respectively arranged on the front and rear ends of the frame, the first wheel group is a driving wheel, and the second wheel group is an omnidirectional wheel. The lawn mowing robot also includes a controller, a first driving module and a second driving module. The controller is connected to the first driving module and the second driving module respectively. The controller controls the first driving module to drive the first wheel group to move and provide the main power for the lawn mowing robot. The controller also controls the second driving module to drive the second wheel group to rotate and provide auxiliary power to overcome the resistance generated by the ground when the second wheel group rotates. When the second driving module drives the second wheel group to rotate, the friction between the auxiliary wheel on the second wheel group and the ground can be reduced, and there is no need to increase the torque on the first wheel group due to the rotation, which can greatly reduce the wear on the lawn.

Description

Technical Field

[0001] The present application relates to the field of robots, and in particular to a lawn mowing robot. Background Art

[0002] The existing lawn mower robot is rear-wheel driven, with the front wheel as the driven wheel. The steering relies on the rear-wheel drive and the front wheel driven to turn in place. However, due to the large wheelbase between the front and rear wheels of the lawn mower robot, the distance between the front wheel and the instantaneous center of the speed of the rear wheel rotation is large (the lever arm is long), so the rear wheel needs to provide a large torque to achieve turning in place. Moreover, due to the high height of the grass and the obvious difference in grass shape during actual lawn movement, the friction between the front and rear wheels of the lawn mower robot and the grass on the grass is higher than that of ordinary hardened ground, especially when turning, the front wheel on the inside has a large rotation resistance and is prone to slipping. When turning, when the front wheel on the inside slips when turning in place, the sliding friction is much greater than the rolling friction during normal rolling. At this time, the rear wheel drive needs to provide a larger torque to achieve turning. Due to the increase in the torque of the rear wheel, the rear wheel rubs the grass seriously, resulting in a poor user experience. Summary of the invention

[0003] In view of this, the present application provides a lawn mowing robot to solve the technical problem of serious grass grinding during the turning process of the lawn mowing robot.

[0004] The lawn mowing robot provided in the present application includes a frame, a first wheel group and a second wheel group, the first wheel group and the second wheel group are respectively arranged on the front and rear ends of the frame, wherein the first wheel group is a driving wheel and the second wheel group is an omnidirectional wheel. The lawn mowing robot also includes a controller, a first driving module and a second driving module, the controller is respectively connected to the first driving module and the second driving module, the controller controls the first driving module to drive the first wheel group to move and provide main power for the lawn mowing robot, and the controller also controls the second driving module to drive the second wheel group to rotate and provide auxiliary power to overcome the resistance between the second wheel group and the ground that needs to be overcome when the second wheel group rotates relative to the ground.

[0005] Since the wheelbase between the first wheel group and the second wheel group of the lawn mower robot is relatively large, when the first wheel group is driven to rotate by the first driving module alone to provide the power for the lawn mower robot to rotate, the second wheel group is at a relatively large distance from the instantaneous center of rotation speed of the first wheel group (the lever arm is relatively long), so that the first wheel group requires the first driving module to provide a relatively large torque to achieve on-the-spot turning. The first wheel group causes relatively large damage to the grass, especially in places with relatively large turning resistance, and may directly wear out the grass; moreover, when the rotation resistance is relatively large, the auxiliary wheels on the second wheel group will change from rolling to sliding, further increasing the friction between the second wheel group and the ground. In the present application, the first driving module provides the main power for the lawn mowing robot, and can drive the lawn mowing robot to move forward, turn or backward, etc. The second driving module drives the second wheel group to rotate and provides auxiliary power to overcome the resistance between the second wheel group and the ground when the second wheel group rotates relative to the ground, which will greatly reduce the friction between the auxiliary wheels on the second wheel group and the ground when the auxiliary wheels on the second wheel group change from lateral sliding to lateral rolling during turning, and during the rotation of the second wheel group, different auxiliary wheels are in contact with the ground at different times, which can reduce the degree of grass grinding. The first driving module does not need to increase the torque of the first wheel group due to turning or turning in place, and only needs to drive the first wheel group to move according to the torque during normal travel. Since the first driving module does not increase the torque when turning or turning in place, the damage to the lawn will not be increased due to the increase in torque, and the wear on the lawn can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0007] Figure 1 It is a schematic diagram of the three-dimensional structure of the lawn mowing robot in the first embodiment of the present application.

[0008] Figure 2 Schematic diagram of the modules of the lawn mowing robot in one embodiment of the present application.

[0009] Figure 3 It is a schematic diagram of the forces acting on the lawn mowing robot in the first embodiment of the present application when it turns clockwise on the spot.

[0010] Figure 4 Schematic diagram of the speed of a lawn mowing robot in one embodiment of the present application.

[0011] Figure 5 Schematic diagram of the structure of the lawn mowing robot in the second embodiment of the present application.

[0012] Figure 6 Schematic diagram of the forces acting on the lawn mowing robot in the second embodiment of the present application when turning clockwise on the spot.

[0013] Figure 7 It is a schematic diagram of the three-dimensional structure of an omnidirectional wheel in one embodiment of the present application.

[0014] Figure 8 for Figure 7 Schematic diagram of the disassembly of the omnidirectional wheel.

[0015] Fig. 9 for Figure 7 Side view of the .

[0016] Fig.10 The diagram is a force diagram of the omnidirectional wheel in one embodiment of the present application when the omnidirectional wheel is a double-row wheel and performs clockwise turning in situ. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0019] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. Similar words such as "one", "an", or "the" used in this application do not indicate a quantitative limitation, but are only used to indicate the existence of at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connected" or connected are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0020] In the description of this specification, the description with reference to the terms "embodiment", "specific embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0021] Please refer to Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the three-dimensional structure of the lawn mowing robot in the first embodiment of the present application; Figure 2 Schematic diagram of a lawn mower robot in an embodiment of the present application. The lawn mower robot 1 includes a frame 11, a first wheel group 12 and a second wheel group 13. The frame 11 is a structure that is wide in the middle and narrow at both ends. The first wheel group 12 and the second wheel group 13 are respectively arranged on the opposite front and rear ends of the frame 11. The first wheel group 12 is a driving wheel, and the second wheel group 13 is an omnidirectional wheel. The lawn mower robot 1 also includes a controller 14, a first drive module 15 and a second drive module 16. The controller 14 is connected to the first drive module 15 and the second drive module 16 respectively. The controller 14 controls the first drive module 15 to drive the first wheel group 12 to move and provide the main power for the lawn mower robot 1. The controller 14 also controls the second drive module 16 to drive the second wheel group 13 to rotate relative to the ground and provide auxiliary power to overcome the resistance generated by the ground when the second wheel group 13 rotates relative to the ground.

[0022] Wherein, the driving wheel is a conventional rubber tire with only one degree of freedom, that is, it rotates along the center line of the wheel axle.

[0023] The omnidirectional wheel is a tire with at least two degrees of freedom. Compared with a conventional rubber tire with only one degree of freedom, the additional degree of freedom of the omnidirectional wheel is located on the tire tread, that is, it can rotate by contacting the ground, and the rotating surface forms a certain angle with the rotating surface of the conventional rubber tire with only one degree of freedom; it can be but not limited to a continuously switching wheel or a Mecanum wheel. Please refer to Figure 1In this embodiment, the omnidirectional wheel is a continuously switching wheel, which includes a wheel hub 130 and a plurality of auxiliary wheels 133, and the plurality of auxiliary wheels 133 are arranged on the wheel hub 130 at intervals. When the omnidirectional wheel moves forward, the wheel hub 130 rotates around the central axis of the omnidirectional wheel, and the wheel hub 130 drives the auxiliary wheels 133 to rotate around the central axis of the omnidirectional wheel as a whole. When the omnidirectional wheel turns, the auxiliary wheels 133 can rotate relative to the wheel hub 130 with the wheel hub 130 as the rotation axis. Therefore, the omnidirectional wheel has an increased degree of freedom relative to the driving wheel.

[0024] Since the wheelbase between the first wheel set 12 and the second wheel set 13 of the lawn mower robot 1 is relatively large, when the first wheel set 12 is driven to rotate only by the first driving module 15 to provide power for the lawn mower robot 1 to move, the second wheel set 13 is at a relatively large distance from the instantaneous center of rotation speed of the first wheel set 12 (a relatively long lever arm), so that the first wheel set 12 requires the first driving module 15 to provide a relatively large torque to achieve in-situ turning. Since the torque required by the first wheel set 12 is increased, the degree of damage to the grass by the first wheel set 12 is also increased accordingly, especially for the ground with relatively large turning resistance, the grass may be directly worn out; moreover, when the rotation resistance is relatively large, the auxiliary wheel 133 on the second wheel set 13 will change from rolling to sliding, further increasing the friction between the second wheel set 13 and the ground. In the present application, the first driving module 15 provides the main power for the lawn mower robot 1, and can drive the lawn mower robot 1 to move forward, turn or move backward, etc. The second driving module 16 drives the second wheel group 13 to rotate relative to the ground and provides auxiliary power to overcome the resistance between the second wheel group 13 and the ground when the second wheel group 13 rotates relative to the ground, which can greatly reduce the friction between the auxiliary wheel 133 on the second wheel group 13 and the ground when the auxiliary wheel 133 on the second wheel group 13 changes from lateral sliding to lateral rolling during turning. In addition, since different auxiliary wheels 133 are in contact with the ground at different times during the rotation of the second wheel group 13 relative to the ground, it can be avoided that the same auxiliary wheel 133 is still in contact with the ground at different times, so that During the rotation of the second wheel group 13, impurities such as grass clippings and dirt stuck between the auxiliary wheels 133 in contact with the ground can be thrown out, thereby reducing the problem of impurities such as grass clippings or dirt stuck between the auxiliary wheels 133. Different auxiliary wheels 133 can be switched to contact the ground to avoid a situation where a certain auxiliary wheel 133 is stuck and cannot rotate and is dragged, thereby reducing the degree of grass grinding. The first driving module 15 does not need to increase the torque of the first wheel group 12 due to turning or turning on the spot, and only needs to drive the first wheel group 12 to move according to the torque during normal travel. Since the first driving module 15 does not increase the torque when turning or turning on the spot, the damage to the lawn will not be increased due to the increase in torque, which can greatly reduce the wear on the lawn.

[0025] In some embodiments, the lawn mowing robot 1 is performing a lawn mowing operation in an area with lush growth. When the grass height is higher than the diameter of the auxiliary wheel 133, when turning or turning on the spot, the grass located on the rotation trajectory directly acts on the wheel hub position to constitute a steering resistance. By rotating the second wheel group 13, with the help of the concave-convex structure on the wheel hub, a part of the grass higher than the auxiliary wheel 133 can be shifted to a position lower than the auxiliary wheel 133, thereby reducing the steering resistance.

[0026] For some examples, please refer to Figure 3 , when the lawn mower robot 1 rotates in place, its instantaneous center of speed A is near the midpoint of the line connecting the axes of the first wheel set 12. Wherein, "near" means that the instantaneous center of speed A does not always coincide with the midpoint of the line connecting the axes of the first wheel set 12, but is within a preset range around the midpoint. The traditional lawn mower robot has two speed matching models, namely, a two-wheel differential model and a four-wheel differential model. The main difference between the two-wheel differential model and the four-wheel differential model is that the instantaneous center of speed of the lawn mower robot of the two-wheel differential model when rotating is located near the center position of the line connecting the axes of the two driving wheels, and the instantaneous center of speed of the lawn mower robot of the four-wheel differential model when rotating is located near the intersection of the cross-connection lines of the four driving wheels. In the present application, although the lawn mower robot 1 includes the second drive module 16, it is still a two-wheel differential model, and its instantaneous center of speed A when rotating is still near the center of the line connecting the axes of the first wheel set 12, so it is different from the traditional four-wheel differential model. Since the front and rear wheels of the traditional four-wheel differential model lawn mower robot 1 are both drive wheels and the constraints of the front and rear wheels are consistent, the steering freedom of the drive wheels is insufficient, and the weight of the whole machine is heavier, so the wear on the lawn is more serious. Since the lawn mower robot 1 of the present application still belongs to the two-wheel differential model, it does not have these shortcomings of the four-wheel differential model. In addition, the lawn mower robot 1 of the present application also adds a second drive module 16 on the basis of the traditional two-wheel differential model, which is used to drive the second wheel group 13 to move and provide auxiliary power to overcome the resistance between the second wheel group 13 and the ground when it rotates relative to the ground. Therefore, it also overcomes the problem that the rear wheels of the lawn mower robot of the traditional two-wheel differential model are easy to wear the grass due to the increased torque.

[0027] In some embodiments, the torque provided by the second drive module 16 only needs to be able to overcome the resistance between the second wheel set 13 and the ground when the second wheel set 13 rotates relative to the ground. Therefore, in fact, the torque provided by the second drive module 16 to the second wheel set 13 is less than the torque provided by the first drive module 15 to the first wheel set 12. Moreover, when turning or rotating in place, the second drive module 16 drives the second wheel set 13 to rotate relative to the ground, which can reduce the friction of the second wheel set 13 when turning and convert the sliding friction into rolling friction. Compared with the traditional two-wheel differential model, when the friction between the grass and the second wheel set 13 is the same, the present application does not need to increase the torque of the first drive module 15 driving the first wheel set 12 because of the large friction between the grass and the second wheel set 13, thereby avoiding the first wheel set 12 from grinding the grass during the turning process.

[0028] In some embodiments, the torque provided by the second driving module 16 to the second wheel set 13 varies with the magnitude of the resistance between the second wheel set 13 and the ground that needs to be overcome when the second wheel set 13 rotates relative to the ground. The driving force provided by the second driving module 16 to the second wheel set 13 is always greater than the resistance between the second wheel set 13 and the ground that needs to be overcome when the second wheel set 13 rotates relative to the ground.

[0029] Therefore, since the grass on the lawn grows differently in different areas, the travel resistance is greater in places where the grass grows luxuriantly, and when the direction of the grass falling is the same as the travel direction, the travel resistance will be relatively smaller. On the contrary, when the direction of the grass falling is opposite to the travel direction, the travel resistance will be greatly increased. Therefore, in the present application, the torque provided by the second drive module 16 to the second wheel set 13 varies with the size of the resistance between the second wheel set 13 and the ground that needs to be overcome when the second wheel set 13 rotates relative to the ground. The torque provided by the second drive module 16 to the second wheel set 13 can be automatically adjusted based on the size of the travel resistance, so as to achieve the purpose of energy saving while meeting the turning requirements.

[0030] In some embodiments, when the lawn mowing robot 1 starts working, the controller 14 controls the second driving module 16 to be in a working state all the time, but the torque provided by the second driving module 16 to the second wheel group 13 is in a changing state. When the resistance between the second wheel group 13 and the ground that needs to be overcome when the second wheel group 13 rotates relative to the ground is very small, the torque provided by the second driving module 16 to the second wheel group 13 is also very small. When the resistance between the second wheel group 13 and the ground that needs to be overcome when the second wheel group 13 rotates relative to the ground is large, the torque provided by the second driving module 16 to the second wheel group 13 also increases accordingly.

[0031] In some other embodiments, the controller 14 controls the second driving module 16 to start when the lawn mower robot 1 turns, and to standby or shut down when the lawn mower robot 1 moves in a straight line, which can further achieve the purpose of energy saving.

[0032] In some specific embodiments, the lawn mower robot 1 includes an angle sensor (not shown), and the angle sensor is connected to the controller 14. The angle sensor generates a turning signal when sensing that the lawn mower robot 1 turns. The controller 14 controls the second drive module 16 to start based on the turning signal to drive the second wheel group 13 to rotate. The angle sensor generates a straight-moving signal when sensing that the lawn mower robot 1 goes straight. It can be understood that "straight-moving" refers to a travel path with a turning radius greater than a preset threshold. The controller 14 controls the first drive module 15 to suspend operation based on the straight-moving signal.

[0033] In some embodiments, the torsion of the second drive module 16 is less than the torque of the first drive module 15, that is, the second drive module 16 is a small torque motor. The second drive module 16 and the first drive module 15 can be, but are not limited to, wheel hub motors, ordinary motors with transmission systems, etc., which are not limited here. In this embodiment, the first drive module 15 and the second drive module 16 are both wheel hub motors.

[0034] In some embodiments, please refer again to Figure 1 , the first wheel group 12 includes a first left wheel 121 and a first right wheel 122. The first driving module 15 includes a first left motor and a first right motor. The first left motor is used to drive the first left wheel 121. The first right motor is used to drive the first right wheel 122. The second wheel group 13 includes a second left wheel 131 and a second right wheel 132. The second driving module 16 includes a second left motor and a second right motor. The second left motor is used to drive the second left wheel 131. The second right motor is used to drive the second right wheel 132. The first left wheel 121, the second left wheel 131, the first right wheel 122 and the second right wheel 132 are independently controlled, and their respective speeds are controlled by the controller 14. During the straight-moving process of the lawn mowing robot 1, the speeds of the first left wheel 121, the second left wheel 131, the first right wheel 122 and the second right wheel 132 are consistent. Please refer to Figure 4 When the lawn mower robot 1 turns in place, the speeds of the first left wheel 121, the first right wheel 122, the second left wheel 131 and the second right wheel 132 are respectively as follows:

[0035] The speed of the first left wheel 121 is

[0036] The speed of the first right wheel 122 is

[0037] The speed of the second right wheel 132 is

[0038] The speed of the second left wheel 131 is

[0039] Wherein, v is the forward speed at the instantaneous center, ω is the rotational angular velocity at the instantaneous center, L is the wheelbase between the first right wheel 122 and the second right wheel 132, or the wheelbase between the first left wheel 121 and the second left wheel 131, d is the wheelbase between the first left wheel 121 and the first right wheel 122, α is the inclination angle of the second left wheel 131 relative to the symmetry axis P of the mowing robot 1, and is also the inclination angle of the second right wheel 132 relative to the symmetry axis P of the mowing robot 1. Moreover, when the mowing robot 1 is at different speeds, the relative sizes of the speeds of the first left wheel 121, the second left wheel 131, the first right wheel 122 and the second right wheel 132 will also be different. In addition, it should be noted that this embodiment only describes the tire speed in a stationary steering mode. If the instantaneous center position is changed, the tire speed relationship will also change. Since the speed relationship can be derived according to the motion posture of the mowing robot, it will not be repeated here.

[0040] In some embodiments, the controller 14 provides corresponding traction to each of the first left side wheel 121, the second left side wheel 131, the first right side wheel 122 and the second right side wheel 132 according to the different speeds of the first left side wheel 121, the second left side wheel 131, the first right side wheel 122 and the second right side wheel 132 to achieve the above-mentioned speed pace.

[0041] Please refer again Figure 3When the lawn mower robot 1 turns on the spot, the traction force received by the first left wheel 121 is F2, and the traction force received by the first right wheel 122 is F1, wherein F2 is the same as and parallel to the moving direction of the lawn mower robot 1. F1 is opposite to F2. The traction force received by the second left wheel 131 is F3, and the traction force received by the second right wheel 132 is F4. Among them, F3 is the same as and parallel to the moving direction of the lawn mower robot 1. F3 is opposite to F4. The rotation direction of the lawn mower robot 1 is M, and the instantaneous center of motion is A, which is located at the center A of the line connecting the axes of the first left wheel 121 and the first right wheel 122. For example, the line connecting the right wheel center point B of the second right wheel 132 and the instantaneous center of velocity A is C, the component of F4 in the vertical direction of the line C is F4a, and the component of F4 on the line C is F4b; similarly, the line connecting the left wheel center D of the second left wheel 131 and the instantaneous center of velocity A is E, the component of F3 in the vertical direction of the line E is F3a, and the component of F3 on the line E is F3b. Among them, the angle between the line C connecting the right wheel center B and the instantaneous center of velocity A and the vertical direction F of the wheel axle of the second right wheel 132 is β2. At this time, F4a=F4*sinβ2. Similarly, F3a can be calculated by similar aspects. F3a enables the second left wheel 131 to overcome the resistance between the second left wheel 131 and the ground when the second left wheel 131 rotates, and F4a enables the second right wheel 132 to overcome the resistance between the second right wheel 132 and the ground when the second right wheel 132 rotates, so that the lawn mower robot 1 can turn more smoothly.

[0042] Please refer to Figure 5 , Figure 5 Schematic diagram of the three-dimensional structure of the lawn mower robot in the second embodiment of the present application. The lawn mower robot 1 in the second embodiment has a similar structure to the lawn mower robot 1 in the first embodiment, except that the lawn mower robot 1 in the second embodiment has a symmetry axis P, and its second wheel set 13 is axially symmetrically arranged relative to the symmetry axis P of the lawn mower robot 1, and the second wheel set 13 is inclined in an eight-shaped arrangement relative to the symmetry axis P. Specifically, the second wheel set 13 includes a second left side wheel 131 and a second right side wheel 132. The second left side wheel 131 and the second right side wheel 132 are symmetrically inclined relative to the symmetry axis P and arranged in an eight-shaped arrangement. Figure 5 In the embodiment, the included angle between the second left wheel 131 and the symmetry axis P of the lawn mower robot 1 is 6 degrees. The included angle between the second right wheel 132 and the symmetry axis P of the lawn mower robot 1 is 6 degrees. It can be understood that in other embodiments, the included angle can be other angles, such as 3 degrees, which is not limited here.

[0043] Please refer to Figure 6, the line connecting the right wheel center point B of the second right wheel 132 and the instantaneous center of velocity A is C, the component of F4 in the vertical direction of the line C is F'4a, and the component of F4 on the line C is F'4b. Similarly, the line connecting the left wheel center D of the second left wheel 131 and the instantaneous center of velocity A is E, the component of F3 in the vertical direction of the line E is F'3a, and the component of F3 on the line E is F'3b. Among them, the angle between the line C connecting the right wheel center B and the instantaneous center of velocity A and the vertical direction F of the wheel axle of the second right wheel 132 is β1. At this time, F'4a=F4*sinβ1. β1 is greater than β2. Similarly, F'3a can be calculated by similar aspects. F'4a is greater than F4a. When the second right wheel 132 is tilted relative to the symmetry axis P of the lawn mower robot 1, the traction force acting on the second left wheel 131 and the second right wheel 132 has a larger component in the rotation direction M, which makes it easier to overcome the friction between the ground, so that the lawn mower robot 1 can turn more smoothly. Moreover, when the lawn mower robot 1 moves in a straight line, since the second left wheel 131 and the second right wheel 132 are relatively tilted, a steering component is still provided to the auxiliary wheel 133, so that the auxiliary wheel 133 maintains a rotation trend. Please refer to Figure 7 As shown in the figure, if the second left wheel 131 and the second right wheel 132 are arranged parallel to the symmetry axis P, when turning in situ, the grass in the rotation direction M directly acts on the auxiliary wheel 133 and the side of the wheel hub 130 (when the grass is higher than the auxiliary wheel 133) to form resistance, so when the second left wheel 131 and the second right wheel 132 are adjusted to be inclined at an angle relative to the symmetry axis P, it is helpful to reduce the resistance of the second left wheel 131 and the second right wheel 132 in the rotation direction M. That is, when the lawn mower robot 1 turns in situ, since the second left wheel 131 and the second right wheel 132 are inclined relative to the symmetry axis P, the resistance of the grass on the side of the second left wheel 131 and the second right wheel 132 is reduced, thereby improving the steering ability of the lawn mower robot 1.

[0044] For some examples, please refer to Figure 8 and Fig. 9 The second left side wheel 131 is a coaxially arranged double-row wheel, and the second right side wheel 132 is also a coaxially arranged double-row wheel.

[0045] Specifically, the double-row wheel comprises a wheel axle 134, a first wheel 135 and a second wheel 136. The wheel axle 134 passes through the first wheel 135 and is fixed on the second wheel 136. The first wheel 135 and the second wheel 136 respectively comprise a wheel hub 130 and a plurality of auxiliary wheels 133, and the plurality of auxiliary wheels 133 are arranged on the wheel hub 130 at intervals. The auxiliary wheels 133 on the first wheel 135 and the auxiliary wheels 133 on the second wheel 136 are arranged alternately, so that all the auxiliary wheels 133 form a complete circle in the vertical plane of the axis of the wheel axle 134, which can improve the smoothness of movement and avoid unevenness during rotation; moreover, the projections of the first wheel 135 and the second wheel 136 in the vertical plane of the axis of the wheel axle 134 overlap, and when the double-row wheel rotates to the point where the auxiliary wheels 133 of the first wheel 135 and the second wheel 136 touch the ground at the same time, the unit pressure of the auxiliary wheels 133 on the ground can be reduced compared with the case where a single auxiliary wheel 133 touches the ground, thereby reducing the damage to the lawn. In addition, the rotation of the auxiliary wheel 133 is conducive to throwing out the debris in the gap between the auxiliary wheel 133 and the wheel axle 134, thereby improving the flexibility of operation.

[0046] Please refer to Fig.10 , Fig.10 The force diagram of the first wheel set in one embodiment of the present application is a double-row wheel and rotates clockwise in place. The double-row wheel of the second left wheel 131 includes a first wheel 135 and a second wheel 136. The center of the first wheel 135 is the first wheel center D1, the center of the second wheel 136 is the second wheel center D2, the line connecting the first wheel center D1 and the instantaneous center of velocity A is E1, and the line connecting the second wheel center D2 and the instantaneous center of velocity A is E2. Obviously, the length of E2 is greater than the length of E1. Therefore, under the same torque, since the lever arm of E2 is longer, the torque of the second wheel center D2 is greater. Therefore, when the second left side wheel 131 rotates until the auxiliary wheel 133 of the first wheel 135 touches the ground, the lever arm is E1, and when the second left side wheel 131 rotates until the auxiliary wheel 133 of the second wheel 136 touches the ground, the lever arm is E2. Therefore, since the auxiliary wheels 133 on the first wheel 135 and the auxiliary wheels 133 on the second wheel 136 are arranged alternately, the lever arm of the second left side wheel 131 changes alternately and periodically between E1 and E2. Even if the power and speed of the second left motor remain unchanged, the torque generated by the second left side wheel 131 under the action of different lever arms is different. When the auxiliary wheel 133 of the first wheel 135 touches the ground, the static friction force that cannot be broken through may be broken through due to the increase in torque and converted into sliding friction force in the rotation path when the auxiliary wheel 133 of the second wheel 136 touches the ground.

[0047] Similarly, the double-row wheels of the second right wheel 132 include a first wheel 135 and a second wheel 136. The center of the first wheel 135 is the third wheel center B1, the center of the second wheel 136 is the fourth wheel center B2, the line connecting the third wheel center B1 and the instantaneous velocity center A is C1, and the line connecting the fourth wheel center B2 and the instantaneous velocity center A is C2. Obviously, the length of C2 is greater than that of C1. Therefore, under the same torque, since the lever arm of C2 is longer, the torque of C2 is greater. Therefore, when the second right side wheel 132 rotates until the auxiliary wheel 133 of the first wheel 135 touches the ground, the lever arm is C1, and when the second right side wheel 132 rotates until the auxiliary wheel 133 of the second wheel 136 touches the ground, the lever arm is C2. Therefore, since the auxiliary wheels 133 on the first wheel 135 and the auxiliary wheels 133 on the second wheel 136 are arranged alternately, the lever arm of the second right side wheel 132 alternately and periodically changes between C1 and C2. Even if the power and speed of the second right side motor remain unchanged, the torque generated by the second right side wheel 132 under the action of different lever arms is different. The static friction force that cannot be broken through when the auxiliary wheel 133 of the first wheel 135 touches the ground may be broken through by the increase of torque and converted into sliding friction in the rotation path when the auxiliary wheel 133 of the second wheel 136 touches the ground.

[0048] In this embodiment, please refer to Figure 1 , the first wheel set 12 is arranged on the rear end of the frame 11, and the second wheel set 13 is arranged on the front end of the frame 11. That is to say, the lawn mowing robot 1 is rear-wheel driven, and the front wheel is an omnidirectional wheel.

[0049] In some other embodiments, the first wheel set 12 is arranged on the front end of the frame 11, and the second wheel set 13 is arranged on the rear end of the frame 11. That is, the lawn mowing robot 1 is front-wheel driven, and the rear wheels are omnidirectional wheels.

[0050] Therefore, in the present application, whether the front wheels or the rear wheels are used as driving wheels, it is easier to turn without grinding the grass, and the equipment cost and energy consumption can be reduced.

[0051] It should be noted that those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by this application. The controller can be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a readily available programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component.

[0052] The above is only a preferred implementation of the present application. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A lawn mowing robot, characterized in that: The lawn mowing robot includes a frame, a first wheel group and a second wheel group, the first wheel group is arranged at the front end or the rear end of the frame, and the second wheel group is correspondingly arranged at the rear end or the front end of the frame, wherein the first wheel group is a driving wheel and the second wheel group is an omnidirectional wheel. The lawn mowing robot also includes a controller, a first driving module and a second driving module, the controller is connected to the first driving module and the second driving module respectively, the controller controls the first driving module to drive the first wheel group to move and provide main power for the lawn mowing robot, and the controller also controls the second driving module to drive the second wheel group to rotate and provide auxiliary power to overcome the resistance generated by the ground when the second wheel group rotates relative to the ground; when the lawn mowing robot rotates in place, its instantaneous center of velocity is adjacent to the midpoint of the line connecting the axis of the first wheel group.

2. The lawn mowing robot according to claim 1, characterized in that: The torque provided by the second driving module to the second wheel set is smaller than the torque provided by the first driving module to the first wheel set.

3. The lawn mowing robot according to claim 2, characterized in that: The torque provided by the second driving module to the second wheel set varies with the magnitude of the resistance generated by the ground when the second wheel set rotates relative to the ground, and the driving force provided by the second driving module to the second wheel set is always greater than the resistance generated by the ground when the second wheel set rotates.

4. The lawn mowing robot according to claim 2 or 3, characterized in that: The lawn mowing robot includes an angle sensor, which is connected to the controller; the angle sensor generates a turning signal when sensing that the lawn mowing robot turns, and the controller controls the second driving module to start working based on the turning signal, and adjusts the torque provided by the second driving module to the second wheel group according to the magnitude of the resistance generated by the ground when the second wheel group rotates.

5. The lawn mowing robot according to claim 1, characterized in that: The second wheel set is arranged in an "eight" symmetric manner relative to the symmetry axis of the lawn mowing robot and is tilted.

6. The lawn mowing robot according to claim 1 or 5, characterized in that: The first wheel group includes a first left wheel and a first right wheel, the first driving module includes a first left motor and a first right motor, the first left motor is used to drive the first left wheel, and the first right motor is used to drive the first right wheel; the second wheel group includes a second left wheel and a second right wheel, the second driving module includes a second left motor and a second right motor, the second left motor is used to drive the second left wheel, and the second right wheel is used to drive the second right motor; when the lawn mower robot rotates, the traction force provided by the second left motor to the second left wheel is a first traction force, and the traction force provided by the second right motor to the second right wheel is a second traction force, and the first traction force is opposite to the second traction force, wherein the component of the first traction force in the vertical direction of the line connecting the instantaneous center of the speed of the lawn mower robot and the center of the tire of the second left wheel is the first traction component, and the component of the second traction force in the vertical direction of the line connecting the instantaneous center of the speed of the lawn mower robot and the center of the tire of the second right wheel is the second traction component, and the first traction component and the second traction component respectively cause the second left wheel and the second right wheel to overcome the resistance generated by the ground when they rotate.

7. The lawn mowing robot according to claim 6, characterized in that: The greater the angle between the line connecting the instantaneous center of the speed of the lawn mowing robot and the center of the tire of the second left wheel and the vertical direction of the wheel axle of the second left wheel, the greater the first traction component force is; the greater the angle between the line connecting the instantaneous center of the speed of the lawn mowing robot and the center of the tire of the second right wheel and the vertical direction of the wheel axle of the second right wheel, the greater the second traction component force is.

8. The lawn mowing robot according to claim 6, characterized in that: The second left side wheel is a coaxially arranged double-row wheel, and the second right side wheel is a coaxially arranged double-row wheel, the double-row wheels include a wheel axle, a first wheel and a second wheel, the wheel axle connects the first wheel and the second wheel, the first wheel and the second wheel each include a wheel hub and a plurality of auxiliary wheels, the plurality of auxiliary wheels are arranged on the wheel hub at intervals, the auxiliary wheels on the first wheel and the auxiliary wheels on the second wheel are arranged alternately, and all the auxiliary wheels form a complete circle in a vertical plane of the axis of the wheel axle.

9. The lawn mowing robot according to any one of claims 1 to 3 and 5, characterized in that: The omnidirectional wheel is one of a continuous switching wheel and a Mecanum wheel.

10. The lawn mowing robot according to any one of claims 1 to 3 and 5, characterized in that: The first wheel set is arranged on the rear end of the frame, and the second wheel set is arranged on the front end of the frame.

11. The lawn mowing robot according to any one of claims 1 to 3 and 5, characterized in that: The first wheel set is arranged on the front end of the frame, and the second wheel set is arranged on the rear end of the frame.

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