Self-propelled device

Abstract

The present application discloses a self-propelled device, comprising a frame, a first wheel set, a second wheel set, and a driving module. The first wheel set and the second wheel set are spaced apart in a first direction, and the first wheel set and the second wheel set are connected to the frame. The driving module is connected to the first wheel set and the second wheel set. The first wheel set is either driving wheels or omnidirectional wheels, and the second wheel set is the other of the driving wheels and the omnidirectional wheels. The load of the driving wheels is greater than the load of the omnidirectional wheels. By connecting the driving module to the first wheel set and the second wheel set, a driving force required when the self-propelled device rotates is distributed to the first wheel set and the second wheel set, thereby reducing turf abrasion caused by slippage of the driving wheels due to insufficient ground friction, reducing damage to lawns. By enabling the load of the driving wheels to be greater than the load of the omnidirectional wheels, the friction between the driving wheels and the ground is increased, thereby increasing the maximum traction of the driving wheels, reducing turf abrasion caused by slippage of the driving wheels due to insufficient ground friction, reducing damage to lawns.

Description

Self-moving device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application No. 202410895992.2, filed on July 04, 2024, and entitled “Self-moving device”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of weeding equipment, in particular to a self-moving device. BACKGROUND

[0004] On the one hand, due to the differences in the growth environment of the grass, the height and the lodging condition of the grass in the lawn are different; on the other hand, the ground flatness of the lawn itself is inconsistent, which leads to the complexity of the self-moving device in the lawn area. The motion stability and the damage to the lawn are two cores of the user's concern in the operation. The motion form of the two-wheel differential self-moving device in the prior art has poor adaptability to the lawn, unstable motion on the lawn, and damage to the lawn caused by the driving wheel slipping when turning. SUMMARY

[0005] Therefore, it is necessary to provide a self-moving device to reduce the damage to the lawn when the self-moving device turns.

[0006] Embodiments of the present application provide a self-moving device, which comprises a rack, a first wheel set, a second wheel set and a driving module. The first wheel set and the second wheel set are arranged at intervals along a first direction, and the first wheel set and the second wheel set are connected to the rack. The driving module is connected to the first wheel set and the second wheel set. The first wheel set is one of a driving wheel and an omni-directional wheel, and the second wheel set is the other one of the driving wheel and the omni-directional wheel. The load of the driving wheel is greater than the load of the omni-directional wheel. By connecting the first wheel set and the second wheel set through the driving module, the driving force required when the self-moving device rotates is distributed to the first wheel set and the second wheel set, which reduces the situation that the driving wheel slips and grinds the grass due to the insufficient friction force provided by the ground, and reduces the damage to the lawn. By increasing the load of the driving wheel greater than the load of the omni-directional wheel, the friction force between the driving wheel and the ground is increased, the upper limit of the driving wheel grip is improved, the situation that the driving wheel slips and grinds the grass due to the insufficient friction force provided by the ground is reduced, and the damage to the lawn is reduced.

[0007] In some embodiments of the present application, along the first direction, the center of gravity of the self-moving device is located between the first wheel set and the second wheel set, and is closer to the driving wheel. By placing the center of gravity of the self-moving device close to the driving wheel, the friction between the driving wheel and the ground is increased, the upper limit of the driving force of the driving wheel is improved, the situation that the driving wheel slips and scratches the grass due to insufficient friction provided by the ground is further reduced, the damage to the lawn is further reduced. When working on some lawn work surfaces with slopes, the center of gravity close to the driving wheel, the driving wheel does not need to provide more driving force to realize the self-moving device turning on the spot along the minimum radius, improve the turning efficiency, reduce the situation that the driving wheel slips and turns, and reduce the power consumption of the self-moving device, and improve the endurance. It should be noted that the driving wheel has only one degree of freedom, which has better stability on the lawn work surface with slopes. When the self-moving device rotates at the minimum radius on the uneven lawn work surface, the center of gravity is close to the rotation center, and the self-moving device can rotate relatively smoothly during rotation, even if part of the omnidirectional wheel does not contact the ground, the main body of the self-moving device can be kept stable.

[0008] In some embodiments of the present application, the rotation center of the self-moving device is located on a straight line passing through the wheel shaft of the driving wheel.

[0009] In some embodiments of the present application, the driving module includes a first driving module and a second driving module. The first wheel set includes a first wheel body and a second wheel body arranged along a second direction, and the second wheel set includes a third wheel body and a fourth wheel body arranged along the second direction, and the first direction is perpendicular to the second direction. The first driving module is connected to the first wheel body and the second wheel body, and the second driving module is connected to the third wheel body and the fourth wheel body.

[0010] In some embodiments of the present application, the driving module includes a first driving module and a second driving module. The first wheel set includes a first wheel body and a second wheel body arranged along a second direction, and the second wheel set includes a third wheel body and a fourth wheel body arranged along the second direction, and the first direction is perpendicular to the second direction. The first driving module is connected to the first wheel body and the third wheel body, and the second driving module is connected to the second wheel body and the fourth wheel body.

[0011] In some embodiments of the present application, when the self-moving device turns on the spot along the minimum radius, the rotation directions of the first wheel body and the third wheel body are the same, and the rotation directions of the second wheel body and the fourth wheel body are opposite to the rotation direction of the first wheel body.

[0012] In some embodiments of the present application, the second driving module comprises a third driving member, the third driving member is connected to a third wheel body, and the traction force on the third wheel body is perpendicular to the axis of the third driving member. A line connecting the rotation center and the center of the third wheel body is defined as a first line, the traction component force of the second driving module on the third wheel body is perpendicular to the first line and points to the rotation direction of the self-moving device. The direction of the traction force and the extension direction of the first line form a first included angle, and the first included angle is negatively correlated with the traction component force on the third wheel body.

[0013] In some embodiments of the present application, the second driving module comprises a fourth driving member, the fourth driving member is connected to a fourth wheel body, and the traction force on the fourth wheel body is perpendicular to the axis of the fourth driving member. A line connecting the rotation center and the center of the fourth wheel body is defined as a second line, the traction component force of the second driving module on the fourth wheel body is perpendicular to the second line and points to the rotation direction of the self-moving device. The direction of the traction force and the extension direction of the second line form a second included angle, and the second included angle is positively correlated with the traction component force on the fourth wheel body.

[0014] In some embodiments of the present application, the first wheel body and the second wheel body are driving wheels, and the third wheel body and the fourth wheel body are omni-directional wheels. The speed of the first wheel body is the same as the speed of the disc of the third wheel body, and the speed of the second wheel body is the same as the speed of the disc of the fourth wheel body.

[0015] In some embodiments of the present application, the speed of the rollers of the third wheel body is the same as the speed of the rollers of the fourth wheel body.

[0016] In some embodiments of the present application, the self-moving device has a symmetry axis, the extension direction of the symmetry axis and the extension direction of the traction force form a third included angle γ, and 0°≤γ≤45°.

[0017] In some embodiments of the present application, the omni-directional wheel comprises a disc and a plurality of rollers fixed to the outer periphery of the disc. The driving module drives the disc to rotate around the axis of the omni-directional wheel, and the plurality of rollers rotate around their own axes. The axis of the disc is perpendicular to the axis of the rollers. The first wheel set and the second wheel set are connected by the driving module. When the advancing direction of the self-moving device changes, the plurality of rollers are sequentially contacted with the grass surface when the disc is driven by the driving module to rotate around the axis of the omni-directional wheel. The rollers can rotate around their own axes, which reduces the difficulty of rotation of the rollers and avoids the same roller being contacted with the grass surface during the rotation process. In this way, the second wheel set can also shake off the grass clippings, soil and other impurities stuck between the rollers contacted with the grass surface during the rotation process, which can reduce the problem of the rollers being stuck by the grass clippings or soil and other impurities. By switching different rollers to be contacted with the ground, the situation that the rollers are stuck can be reduced, which is conducive to reducing the situation that the rollers slip with the grass surface and cause grass abrasion, and reducing the damage to the lawn.

[0018] In some embodiments of the present application, the third wheel body is an omni-directional wheel, the third wheel body includes two omni-directional wheels, the second driving module passes through one of the omni-directional wheels and is connected to the other omni-directional wheel, and there is a gap between the rollers of adjacent omni-directional wheels. The two omni-directional wheels are driven to rotate by the third driving member, so that the plurality of rollers successively contact the grass surface and rotate along their own axes, which is beneficial to shake off the soil, grass and other sundries in the gap, improve the flexibility of operation, and reduce the situation that the rollers are stuck and cause the rollers to slip and wear the grass

[0019] In some embodiments of the present application, the omni-directional wheel includes one of a continuous switching wheel and a Mecanum wheel.

[0020] The self-moving device of the present application connects the first wheel set and the second wheel set through the driving module, distributes the driving force required when the self-moving device rotates to the first wheel set and the second wheel set, reduces the situation that the driving wheel slips and wears the grass due to the fact that the ground cannot provide sufficient friction, and reduces the damage to the lawn. The load of the driving wheel is greater than the load of the omni-directional wheel, the friction between the driving wheel and the ground is increased, the upper limit of the driving wheel grip is improved, the situation that the driving wheel slips and wears the grass due to the fact that the ground cannot provide sufficient friction is reduced, and the damage to the lawn is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 illustrates a structural schematic diagram of a self-moving device in an embodiment of the present application.

[0022] FIG. 2 illustrates a module schematic diagram of a self-moving device in an embodiment of the present application.

[0023] FIG. 3 illustrates a speed matching schematic diagram of a first wheel set and a second wheel set in an embodiment of the present application.

[0024] FIG. 4 illustrates a force schematic diagram of a self-moving device rotating clockwise in an embodiment of the present application.

[0025] FIG. 5 illustrates a counterclockwise rotation schematic diagram of a self-moving device in an embodiment of the present application.

[0026] FIG. 6 illustrates a force schematic diagram of a self-moving device rotating in the embodiment of FIG. 5 of the present application.

[0027] FIG. 7 illustrates a structural schematic diagram of an omni-directional wheel in an embodiment of the present application.

[0028] FIG. 8 illustrates a structural schematic diagram of an omni-directional wheel from another perspective in an embodiment of the present application.

[0029] FIG. 9 illustrates a force schematic diagram of a self-moving device rotating clockwise in another embodiment of the present application.

[0030] FIG. 10 illustrates an exploded schematic diagram of an omni-directional wheel in an embodiment of the present application.

[0031] Figure 11 illustrates an exploded view of the omni-directional wheel from another perspective, according to an embodiment of the application.

[0032] Figure 12 illustrates a force diagram of the self-moving device rotating clockwise, according to an embodiment of the application.

[0033] Main element symbol explanation Self-moving device 100 Frame 10 First wheel set 20 First wheel body 21 Second wheel body 22 Second wheel set 30 Wheel disc 301 Roll 302 Gap 303 Fixed part 304 Opening 304a End cover 305 Accommodation part 306 Third wheel body 31 Fourth wheel body 32 Driving module First driving module 41 First driving part 411 Second driving part 412 Second driving module 42 Third driving part 421 Fourth driving part 422 Control module 50 Gravity center A Rotation center B First connecting lineSecond connecting line C Symmetrical axis P First included angle β1 Second included angle β2 Third included angle γ First direction X Second direction Y

[0034] The following detailed embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0035] The following detailed embodiments are illustrative and not restrictive, and are intended to provide a basic understanding of the application. The key or critical elements of the application are not to be identified or determined from the detailed description, but are identified or determined only from the claims. As long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way.

[0036] When a component is considered to be "provided on" another component, it can be directly provided on the other component or can have a middle component therebetween. When a component is considered to be "connected" to another component, it can be directly connected to the other component or can have a middle component therebetween.

[0037] It can be understood that the term "perpendicular" is used to describe the ideal state between two components. In the actual production or use state, there can be a state close to or equal to perpendicular between the two components. For example, in conjunction with numerical description, perpendicular can refer to the included angle between two straight lines in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes in the range of 90°±10°, and perpendicular can also refer to the included angle between a straight line and a plane in the range of 90°±10°. The two components described as "perpendicular" can not be absolute straight lines or planes, but can be approximately straight lines or planes, and as a whole, the overall extension direction is a straight line or a plane, which can be considered as a "straight line" or a "plane".

[0038] Unless otherwise defined, the term "plurality" used herein to describe the number of components specifically refers to two or more of the components.

[0039] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0040] Referring to FIG. 1, an embodiment of the present application provides a self-moving device 100, comprising a frame 10, a first wheel set 20, a second wheel set 30 and a driving module 40. The first wheel set 20 and the second wheel set 30 are arranged along a first direction X, and the first wheel set 20 and the second wheel set 30 are connected to the frame 10. The driving module 40 is connected to the first wheel set 20 and the second wheel set 30. The first wheel set 20 is one of a driving wheel and an omni-directional wheel, and the second wheel set 30 is the other one of the driving wheel and the omni-directional wheel. The load of the driving wheel is greater than the load of the omni-directional wheel.

[0041] The present application distributes the driving force required for the rotation of the self-moving device 100 to the first wheel set 20 and the second wheel set 30 through the driving module 40, reduces the situation that the driving wheel slips and grinds the grass due to the insufficient friction provided by the ground, and reduces the damage to the lawn. By increasing the friction between the driving wheel and the ground, the upper limit of the driving wheel's grip is improved, the situation that the driving wheel slips and grinds the grass due to the insufficient friction provided by the ground is reduced, and the damage to the lawn is reduced.

[0042] In some embodiments, along the first direction X, the center of gravity G of the self-moving device 100 is located between the first wheel set 20 and the second wheel set 30, and is closer to the driving wheel. By moving the center of gravity G of the self-moving device 100 closer to the driving wheel, the friction between the driving wheel and the ground is increased, the upper limit of the driving wheel's grip is improved, the situation that the driving wheel slips and grinds the grass due to the insufficient friction provided by the ground is further reduced, and the damage to the lawn is further reduced.

[0043] In some embodiments, along the first direction X, the center of gravity G of the self-moving device 100 is located between the first wheel set 20 and the second wheel set 30, and is closer to the driving wheel. When working on a lawn working surface with a slope, the center of gravity G is close to the driving wheel, and the driving wheel does not need to provide more driving force to realize the self-moving device 100 turning on the spot along the minimum radius, improve the turning efficiency, reduce the situation that the driving wheel slips and turns, and reduce the power consumption of the self-moving device 100 and improve the endurance. It should be noted that the driving wheel has only one degree of freedom, and has better stability on the lawn working surface with a slope.

[0044] Please refer to FIG. 4, in some embodiments, along the first direction X, the center of gravity G of the self-moving device 100 is located between the first wheel set 20 and the second wheel set 30, and is closer to the driving wheel. When the self-moving device 100 works on the uneven lawn working surface, the center of gravity G is close to the rotation center A when the self-moving device 100 rotates at the minimum radius, and the self-moving device 100 can rotate stably during rotation, even if part of the omni-directional wheel is not in contact with the lawn ground, the self-moving device main body can also be kept stable. It should be noted that when the robot rotates at the minimum radius, the robot itself is based on the center position of the rotation center on the connecting line of the driving wheel shaft, which is not equal to the minimum value of the rotation radius adopted when the self-moving device is controlled to rotate.

[0045] In some embodiments, the first wheel set 20 is a driving wheel, and the second wheel set 30 is an omni-directional wheel. Along the first direction X, the distance between the center of gravity G of the self-moving device 100 and the first wheel set 20 is less than the distance between the center of gravity G and the second wheel set 30, and the center of gravity G is closer to the first wheel set 20.

[0046] In some embodiments, the first wheel set 20 is an omni-directional wheel, and the second wheel set 30 is a driving wheel. Along the first direction X, the distance between the center of gravity G of the self-moving device 100 and the first wheel set 20 is greater than the distance between the center of gravity G and the second wheel set 30, and the center of gravity G is closer to the second wheel set 30.

[0047] The present application takes the first wheel set 20 as a driving wheel and the second wheel set 30 as an omni-directional wheel as an example for description.

[0048] In some embodiments, the driving wheel is a rubber tire with one degree of freedom, and the driving wheel rotates along its own axis.

[0049] In some embodiments, the omni-directional wheel is a tire with at least two degrees of freedom, and the increased degree of freedom of the omni-directional wheel is located on the tire tread, that is, rotation can be generated by contact with the ground.

[0050] In some embodiments, the omni-directional wheel includes a continuous switching wheel or a Mecanum wheel.

[0051] In some embodiments, the driving wheel is a tire with two degrees of freedom, the driving wheel rotates along its own axis, and can be deflected relative to the symmetry axis P of the self-moving device 100, which is beneficial for the self-moving device 100 to turn.

[0052] In some embodiments, referring to FIG. 1, FIG. 7 and FIG. 8, the omni-directional wheel includes a wheel disc 301 and a plurality of rollers 302 fixed on the outer periphery of the wheel disc 301, the axis of the wheel disc 301 is perpendicular to the axis of the rollers 302. The first wheel group 20 and the second wheel group 30 are connected by the driving module 40, when the traveling direction of the self-moving device 100 changes, the plurality of rollers 302 are sequentially contacted with the grass surface when the wheel disc 301 is rotated around the axis of the omni-directional wheel driven by the driving module 40, the rollers 302 can rotate around their own axis, which reduces the difficulty of rotation of the rollers 302, and avoids the same roller 302 being contacted with the grass surface during rotation. In this way, the second wheel group 30 can also shake off the grass clippings, soil and other impurities stuck between the rollers 302 contacted with the grass surface during rotation, which can reduce the problem of grass clippings or soil and other impurities being stuck between the rollers 302, reduce the situation of the rollers 302 being stuck, and be conducive to reducing the situation of the rollers 302 slipping with the grass surface and causing grass to be ground, and reducing the damage to the lawn.

[0053] In some embodiments, the driving module 40 includes a first driving module 41 and a second driving module 42, the first driving module 41 is connected to the first wheel group 20, and the second driving module 42 is connected to the second wheel group 30.

[0054] In some embodiments, the first driving module 41 is configured to provide power to drive the first wheel group 20 to rotate, and the second driving module 42 is configured to provide power to drive the second wheel group 30 to rotate.

[0055] In some embodiments, the self-moving device 100 includes a control module 50, the control module 50 is electrically connected to the first driving module 41, and the control module 50 controls the torque output by the first driving module 41.

[0056] In some embodiments, the control module 50 is electrically connected to the second driving module 42, and the control module 50 controls the torque output by the second driving module 42. The control module 50 adjusts the torque of the second driving module 42 driving the second wheel group 30 based on the resistance received by the self-moving device 100 when rotating, and the torque of the second driving module 42 driving the second wheel group 30 is greater than the resistance received by the second wheel group 30 when the self-moving device 100 rotates.

[0057] For example, the control module 50 can be, but is not limited to, a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a ready programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component.

[0058] In some embodiments, since the growth of grass on the grassland is different in different areas, the growth of grass in some areas is more vigorous, and the resistance to movement is greater. When the direction of the fallen grass is the same as the direction of movement, the resistance to movement is relatively small. Conversely, when the direction of the fallen grass is opposite to the direction of movement, the resistance to movement is greatly increased. Therefore, in this application, the torque provided by the second driving module 42 to the second wheel set 30 changes with the resistance between the second wheel set 30 and the ground when the second wheel set 30 rotates relative to the ground. The torque provided by the second driving module 42 to the second wheel set 30 can be automatically adjusted based on the size of the resistance to movement, and the purpose of energy saving can be achieved under the condition of meeting the turning requirement.

[0059] In other embodiments, the control module 50 controls the second driving module 42 to start when the self-moving device 100 turns, and the second driving module 42 is in standby or off when the self-moving device 100 moves straight, which can further achieve the purpose of energy saving.

[0060] In some embodiments, the self-moving device 100 includes a posture sensor (not shown in the figure), which is connected to the control module 50. The self-moving device 100 turns based on the planned path and generates a turning signal. The control module 50 controls the second driving module 42 to start to drive the second wheel set 30 to rotate based on the turning signal. The posture sensor continuously detects the turning posture of the self-moving device 100, and generates a feedback signal if the detected posture is inconsistent with the expected posture. The control module 50 regenerates the turning signal based on the feedback signal, and the control module 50 controls the second driving module 42 to start to drive the second wheel set 30 to rotate based on the new turning signal. The self-moving device 100 generates a straight signal when it moves straight, and the control module 50 controls the second driving module 42 to start to drive the second wheel set 30 to move straight based on the straight signal. The posture sensor continuously detects the straight posture of the self-moving device 100, and generates a feedback signal if the detected posture is inconsistent with the expected posture. The control module 50 regenerates the straight signal based on the feedback signal, and the control module 50 controls the second driving module 42 to start to drive the second wheel set 30 to move straight based on the new straight signal.

[0061] Please refer to FIG. 1. In some embodiments, the first wheel set 20 includes a first wheel body 21 and a second wheel body 22 arranged along a second direction Y, and the first driving module 41 is connected to the first wheel body 21 and the second wheel body 22. The first direction X is perpendicular to the second direction Y.

[0062] In some embodiments, the second wheel set 30 includes a third wheel body 31 and a fourth wheel body 32 arranged along the second direction Y. The second driving module 42 is connected to the third wheel body 31 and the fourth wheel body 32.

[0063] In some embodiments, the first wheel body 21 and the second wheel body 22 are drive wheels, and the third wheel body 31 and the fourth wheel body 32 are omni-directional wheels.

[0064] Please refer to FIG. 2 to FIG. 6, in some embodiments, the rotation center A of the self-moving device 100 is located on a straight line passing through the wheel shaft of the driving wheel. The present application takes the rotation center of the self-moving device 100 when it turns on the spot along the minimum radius as an example, and takes the rotation center of the self-moving device 100 when it turns away from the rotation center of the self-moving device 100 as an example.

[0065] As shown in FIG. 4, in some embodiments, when the self-moving device 100 turns on the spot along the minimum radius, the rotation center A of the self-moving device 100 is located at or near the center of the line connecting the axis of the first wheel body 21 and the axis of the second wheel body 22.

[0066] In some embodiments, along the first direction X, the rotation center A and the center of gravity G are located on the axis of symmetry P, which is beneficial for the self-moving device 100 to turn around the rotation center A and reduce the damage to the lawn caused by skidding and grinding.

[0067] In some embodiments, along the first direction X, the center of gravity G is closer to the rotation center A than the second wheel group 30, which is beneficial for the self-moving device 100 to turn around the rotation center A along the minimum radius and reduce the damage to the lawn caused by skidding and grinding. As shown in FIG. 4, the line connecting the third wheel body 31 and the center of the fourth wheel body 32 is compared with W, along the first direction X, the distance between the rotation center A and the center of gravity G is less than the distance between the center of gravity G and W.

[0068] Traditional self-moving devices have two-wheel differential model and four-wheel differential model, the main difference between the two-wheel differential model and the four-wheel differential model is that the rotation center of the lawn mower robot in the two-wheel differential model is located near the center of the line connecting the axes of the two driving wheels, and the rotation center of the lawn mower robot in the four-wheel differential model is located near the intersection of the intersecting line of the four driving wheels. In the present application, although the self-moving device 100 includes the second driving module 42, the rotation center A of the self-moving device 100 when it rotates is still near the center of the line connecting the axes of the two driving wheels, so it is different from the traditional four-wheel differential model. Because the front and rear wheels of the traditional four-wheel differential model self-moving device belong to the driving wheels and the respective constraints of the front and rear wheels are consistent, the steering freedom of the driving wheels is not enough, and the overall weight is heavier, so the wear of the lawn is more serious. The self-moving device 100 of the present application still belongs to the two-wheel differential model, so it does not have the shortcomings of the four-wheel differential model. Moreover, the self-moving device 100 of the present application also increases the second driving module 42 on the basis of the traditional two-wheel differential model and the load of the driving wheel is greater than that of the omni-directional wheel, so it also overcomes the problem that the rear wheel of the traditional two-wheel differential model self-moving device is easy to skid and grind the grass.

[0069] As shown in FIG. 4, in some embodiments, when the self-moving device 100 turns on the spot along the minimum radius, the rotation directions of the first wheel body 21 and the third wheel body 31 are the same, and the rotation directions of the second wheel body 22 and the fourth wheel body 32 are opposite to that of the first wheel body 21. For example, when the self-moving device 100 turns on the spot along the clockwise direction M, the first wheel body 21 and the third wheel body 31 rotate forward, and the second wheel body 22 and the fourth wheel body 32 rotate backward.

[0070] In some embodiments, the first driving module 41 comprises a first driving member 411 and a second driving member 412, the first driving member 411 is connected to the first wheel body 21, and the second driving member 412 is connected to the second wheel body 22.

[0071] For example, the first driving member 411 and the second driving member 412 comprise, but are not limited to, a hub motor, a common motor cooperating with a transmission system, etc.

[0072] In some embodiments, the second driving module 42 comprises a third driving member 421 and a fourth driving member 422, the third driving member 421 is connected to the third wheel body 31, and the fourth driving member 422 is connected to the fourth wheel body 32.

[0073] For example, the third driving member 421 and the fourth driving member 422 comprise, but are not limited to, a hub motor, a common motor cooperating with a transmission system, etc.

[0074] In other embodiments, the first driving module 41 comprises a first driving member 411, the first wheel body 21 and the third wheel body 31 are connected by a transmission shaft, and the first driving member 411 is connected to the transmission shaft. The second driving module 42 comprises a third driving member 421, the second wheel body 22 and the fourth wheel body 32 are connected by another transmission shaft, and the third driving member 421 is connected to the transmission shaft. This can reduce the number of driving members, which is conducive to reducing the weight of the self-moving device 100 and improving the endurance of the self-moving device 100.

[0075] In other embodiments, the driving module 40 comprises a first driving module 41, the first driving module 41 comprises a first driving member 411, and the first driving member 411 is connected to the first wheel body 21, the second wheel body 22, the third wheel body 31 and the fourth wheel body 32 through a transmission shaft.

[0076] As shown in FIG. 3, in some embodiments, when the self-moving device 100 moves along the first direction X, the first wheel body 21, the second wheel body 22, the third wheel body 31 and the fourth wheel body 32 have the same speed ratio.

[0077] In some embodiments, when the self-moving device 100 turns on the spot along the minimum radius:

[0078] The speed ratio of the first wheel body 21

[0079] The speed ratio of the second wheel body 22

[0080] The speed ratio of the third wheel body 31 cosα+ωLsinα;

[0081] The speed ratio of the fourth wheel body 32 cosα-ωLsinα.

[0082] Wherein, v is the forward speed at the rotation center A, ω is the rotation angular velocity at the rotation center A, L is the wheelbase between the first wheel body 21 and the third wheel body 31, or the wheelbase between the second wheel body 22 and the fourth wheel body 32, d is the wheelbase between the first wheel body 21 and the second wheel body 22, and α is the inclination angle of the third wheel body 31 relative to the symmetry axis P of the self-moving device 100, which is also the inclination angle of the fourth wheel body 32 relative to the symmetry axis P of the self-moving device 100. Moreover, the speed ratios of the first wheel body 21, the third wheel body 31, the second wheel body 22 and the fourth wheel body 32 are different at different rotation speeds of the self-moving device 100. In addition, it should be noted that the embodiment only illustrates the tire speed ratio in the case of the original steering mode, and the tire speed ratio will change if the position of the rotation center A is changed. Since the speed ratio relationship can be deduced according to the motion posture of the self-moving device 100, it is not described here.

[0083] In some embodiments, the control module 50 provides a corresponding traction force for each of the first wheel body 21, the third wheel body 31, the second wheel body 22 and the fourth wheel body 32 according to the different speed ratios of the first wheel body 21, the third wheel body 31, the second wheel body 22 and the fourth wheel body 32, so as to realize the above-mentioned speed ratios.

[0084] By the speed ratios of the first wheel body 21, the second wheel body 22, the third wheel body 31 and the fourth wheel body 32, and by taking the center of the line connecting the axis of the first wheel body 21 and the axis of the second wheel body 22 as the rotation center A, the self-moving device 100 realizes the original steering along the minimum radius, which overcomes the problem of easy skidding and grass damage of the traditional two-wheel differential model and four-wheel differential model.

[0085] Please refer to FIG. 4, in some embodiments, the third driving member 421 is connected to the third wheel body 31. The traction force of the second driving module 42 on the third wheel body 31 is perpendicular to the axis of the third driving member 421.

[0086] In some embodiments, a line connecting the rotation center A and the center a of the third wheel body 31 is defined as a first line B, and the traction force of the second driving module 42 on the third wheel body 31 is perpendicular to the first line B and points to the rotation direction of the self-moving device 100. The direction of the traction force on the third wheel body 31 forms a first included angle β1 with the extension direction of the first line B, and the first included angle β1 is negatively correlated with the traction force on the third wheel body 31. That is, the larger the first included angle β1, the smaller the traction force on the third wheel body 31.

[0087] In some embodiments, the fourth driving member 422 is connected to the fourth wheel body 32. The traction force of the second driving module 42 on the fourth wheel body 32 is perpendicular to the axis of the fourth driving member 422.

[0088] In some embodiments, a line connecting the rotation center A and the center b of the fourth wheel body 32 is defined as a second line C, and the traction force of the second driving module 42 on the fourth wheel body 32 is perpendicular to the second line C and points to the rotation direction of the self-moving device 100. The direction of the traction force on the fourth wheel body 32 forms a second included angle β2 with the extension direction of the second line C, and the second included angle β2 is positively correlated with the traction force on the fourth wheel body 32. That is, the larger the second included angle β2, the larger the traction force on the fourth wheel body 32.

[0089] Please refer to FIG. 4, and taking the clockwise rotation M of the self-moving device 100 as an example for description. For the convenience of description, the traction force on the first wheel body 21 is defined as a first traction force F1, and the traction force on the second wheel body 22 is defined as a second traction force F2.

[0090] The traction force on the third wheel body 31 is defined as a third traction force F3, and the third traction force F3 is perpendicular to the axis of the third driving member 421. The forward rotation of the first wheel body 21 and the third wheel body 31 makes the directions of the first traction force F1 and the third traction force F3 the same.

[0091] The first traction component of the third traction force F3 on the third wheel body 31 is defined as F3a, and the second traction component is defined as F3b, wherein the first traction component F3a is perpendicular to the first line B, and the second traction component F3b is located on the first line B and points to the direction away from the rotation center A. At this time, F3a=F3*sin(180°-β1), and β1 is an obtuse angle. The third traction force F3 drives the wheel disc 301 of the third wheel body 31 to rotate around the axis of the omnidirectional wheel, so that the plurality of rollers 302 are sequentially contacted with the grass surface. The first traction component F3a drives the rollers 302 to rotate around their own axes, so that the third wheel body 31 overcomes the resistance between the third wheel body 31 and the ground when rotating under the action of the first traction component F3a, so that the self-moving device 100 can turn more smoothly, reduce the occurrence of skidding and grass grinding, and reduce the damage to the lawn.

[0092] The fourth traction force F4 is defined as the traction force on the fourth wheel body 32, and the fourth traction force F4 is perpendicular to the axis of the fourth driving member 422. The second wheel body 22 and the fourth wheel body 32 rotate rearward, so that the directions of the second traction force F2 and the fourth traction force F4 are the same, and the directions of the first traction force Fl and the third traction force F3 are opposite.

[0093] The third traction component F4a and the fourth traction component F4b are defined as the third traction component F4a being perpendicular to the second connecting line C and the fourth traction component F4b being located on the first connecting line B and pointing to the rotation center A. At this time, F4a = F4*sinβ2, and β2 is an acute angle. The fourth traction force F4 drives the wheel disc 301 of the fourth wheel body 32 to rotate around the axis of the omnidirectional wheel, so that the plurality of rollers 302 are sequentially in contact with the grass surface. The third traction component F4a drives the roller 302 to rotate around its own axis, so that the fourth wheel body 32 overcomes the resistance between the fourth wheel body 32 and the ground when rotating, so that the self-moving device 100 can turn more smoothly, reduce the situation of slipping and grinding the grass, and reduce the damage to the lawn.

[0094] In some embodiments, when the self-moving device 100 turns in place along the minimum radius, the first wheel body 21 forms a first circular trajectory, and the direction of the first traction force Fl on the first wheel body 21 is always tangent to the first circular trajectory. The second wheel body 22 forms a second circular trajectory, and the direction of the second traction force F2 on the second wheel body 22 is always tangent to the second circular trajectory. The third wheel body 31 forms a third circular trajectory, and the direction of the first traction component F3a on the third wheel body 31 is always tangent to the third circular trajectory. The fourth wheel body 32 forms a fourth circular trajectory, and the direction of the third traction component F4a on the fourth wheel body 32 is always tangent to the fourth circular trajectory.

[0095] As shown in FIG. 5, the rotation center A is away from the self-moving device 100 and located on a straight line passing through the axis of the first wheel body 21 and the axis of the second wheel body 22.

[0096] In some embodiments, when the self-moving device 100 turns away from the rotation center A of the self-moving device 100, the rotation directions of the first wheel body 21 and the third wheel body 31 are the same, the rotation directions of the second wheel body 22 and the fourth wheel body 32 are the same as the rotation direction of the first wheel body 21, and the rotation directions of the first wheel body 21 and the second wheel body 32 are the same.

[0097] In some embodiments, when the self-moving device 100 turns counterclockwise away from the rotation center A of the self-moving device 100, the rotation speed of the first wheel body 21 is less than the rotation speed of the third wheel body 31, the rotation speed of the third wheel body 31 is less than the rotation speed of the second wheel body 22, and the rotation speed of the second wheel body 22 is less than the rotation speed of the fourth wheel body 32.

[0098] Please refer to FIG. 5 and FIG. 6, and take the self-moving device 100 turning counterclockwise away from the rotation center A of the self-moving device 100 as an example for description. For the convenience of description, the traction force received by the first wheel body 21 is defined as the fifth traction force F5, and the traction force received by the second wheel body 22 is defined as the sixth traction force F6.

[0099] In some embodiments, the first wheel body 21 turns counterclockwise away from the rotation center A of the self-moving device 100 to form a fifth circular trajectory R1, and the direction of the fifth traction force F5 is always tangent to the fifth circular trajectory R1.

[0100] In some embodiments, the first wheel body 21 turns counterclockwise away from the rotation center A of the self-moving device 100 to form a sixth circular trajectory R2, and the direction of the sixth traction force F6 is always tangent to the sixth circular trajectory R2.

[0101] In some embodiments, the first traction resultant force F7 received by the third wheel body 31 is defined as F7, the fifth traction component force F7a is defined as F7a, and the sixth traction component force F7b is defined as F7b. The fifth traction component force F7a is perpendicular to the axis direction of the third driving member 421, and the sixth traction component force F7b is located in the axis direction of the third wheel body 31 and faces the rotation center A. The first traction resultant force F7 is the resultant force of the fifth traction component force F7a and the sixth traction component force F7b.

[0102] In some embodiments, the third wheel body 31 turns counterclockwise away from the rotation center A of the self-moving device 100 to form a seventh circular trajectory R3, and the direction of the first traction resultant force F7 is always tangent to the seventh circular trajectory R3.

[0103] In some embodiments, the second traction resultant force F8 received by the fourth wheel body 32 is defined as F8, the seventh traction component force F8a is defined as F8a, and the eighth traction component force F8b is defined as F8b. The seventh traction component force F8a is perpendicular to the axis direction of the fourth driving member 422, and the eighth traction component force F8b is located in the axis direction of the fourth wheel body 32 and faces the rotation center A. The second traction resultant force F8 is the resultant force of the seventh traction component force F8a and the eighth traction component force F8b.

[0104] In some embodiments, the fourth wheel body 32 turns counterclockwise away from the rotation center A of the self-moving device 100 to form an eighth circular trajectory R4, and the direction of the second traction resultant force F8 is always tangent to the eighth circular trajectory R4.

[0105] Please refer to FIG. 6, in some embodiments, when the rotation center A of the self-moving device 100 is located on the straight line passing through the wheel shaft of the driving wheel, the first wheel body 21 has a speed ratio of v5, the second wheel body 22 has a speed ratio of v6, the wheel disc 301 of the third wheel body 31 has a speed ratio of v7a, the roller 302 of the third wheel body 31 has a speed ratio of v7b, the wheel disc 301 of the fourth wheel body 32 has a speed ratio of v8a, and the roller 302 of the fourth wheel body 32 has a speed ratio of v8b.

[0106] In some embodiments, taking the case that the self-moving device 100 turns counterclockwise away from the rotation center A of the self-moving device 100 as an example, v5 = v7a and v6 = v8a.

[0107] In some embodiments, taking the case that the self-moving device 100 turns counterclockwise away from the rotation center A of the self-moving device 100 as an example, v7b = v8b.

[0108] By setting the speed ratios of the first wheel body 21, the second wheel body 22, the third wheel body 31 and the fourth wheel body 32, the self-moving device 100 can realize turning, reduce the problem of skidding and grass damage when the self-moving device 100 turns, and reduce the damage to the lawn.

[0109] It can be understood that the speed ratio relationship of the first wheel body 21, the second wheel body 22, the third wheel body 31 and the fourth wheel body 32 is not limited to the above-mentioned position away from the rotation center A of the self-moving device 100, as long as the rotation center A of the self-moving device 100 is located on the straight line passing through the wheel shaft of the driving wheel, the above-mentioned speed ratio relationship is met.

[0110] Please refer to FIG. 9, in some embodiments, the extension direction of the symmetry axis P and the extension direction of the traction force form a third included angle γ, 0° ≤ γ ≤ 45°. For example, γ can be any one of the integer values of 0°-45°.

[0111] When γ is 0°, as shown in FIG. 4, the third wheel body 31 and the fourth wheel body 32 are arranged in parallel in the second direction Y.

[0112] When γ is greater than 0° and less than or equal to 30°, as shown in FIG. 9, the third wheel body 31 and the fourth wheel body 32 are arranged in an eight-shaped manner relative to the symmetry axis P. The extension direction of the symmetry axis P and the extension direction of the third traction force F3 form a third included angle γ, and the extension direction of the symmetry axis P and the extension direction of the fourth traction force F4 form a third included angle γ, so that the second wheel set 30 is arranged in an eight-shaped manner relative to the symmetry axis P, and the first traction component F3a and the third traction component F4a are improved, which is beneficial to overcome the resistance between the third wheel body 31 and the fourth wheel body 32 and the ground when they rotate, so that the self-moving device 100 can turn more smoothly.

[0113] Please refer to FIG. 9, taking the fourth wheel body 32 as an example, when the fourth wheel body 32 is arranged obliquely relative to the symmetry axis P, F4a' = F4*sin(β2+γ), F4a' is greater than F4a, therefore, when the fourth wheel body 32 is arranged obliquely relative to the symmetry axis P, the component of the traction force acting on the fourth wheel body 32 in the rotation direction M is greater, which overcomes the resistance between the fourth wheel body 32 and the ground when the fourth wheel body 32 rotates, so that the self-moving device 100 can turn more smoothly at the spot. Similarly, when the third wheel body 31 is arranged obliquely relative to the symmetry axis P, the component of the traction force acting on the third wheel body 31 in the rotation direction M is greater, which overcomes the resistance between the third wheel body 31 and the ground when the third wheel body 31 rotates, so that the self-moving device 100 can turn more smoothly at the spot.

[0114] When the third wheel body 31 and the fourth wheel body 32 are arranged parallel relative to the symmetry axis P, the grass in the rotation direction M directly acts on the side of the roller 302 and the wheel disc 301 (when the grass is higher than the roller 302) to form resistance when turning at the spot along the minimum radius. When the third wheel body 31 and the fourth wheel body 32 are adjusted to be arranged obliquely relative to the symmetry axis P at an angle, the resistance of the third wheel body 31 and the fourth wheel body 32 in the rotation direction M is reduced. When the self-moving device 100 turns at the spot, because the third wheel body 31 and the fourth wheel body 32 are arranged obliquely relative to the symmetry axis P, the resistance of the side of the third wheel body 31 and the fourth wheel body 32 to the grass is reduced, which is beneficial to improve the turning ability of the self-moving device 100.

[0115] Please refer to FIG. 7, FIG. 10 to FIG. 12, in some embodiments, the second wheel set 30 includes two third wheel bodies 31, both of which are omni-directional wheels, and the two omni-directional wheels are arranged along the second direction Y, which reduces the damage to the lawn compared with the case that a single omni-directional wheel is grounded.

[0116] In some embodiments, the third driving member 421 passes through one of the omni-directional wheels and is connected to the other omni-directional wheel, and a gap 303 is formed between the two adjacent omni-directional wheels. The two omni-directional wheels are driven to rotate by the third driving member 421, so that the plurality of rollers 302 sequentially contact the grass surface and rotate along their own axes, which is beneficial to shake off the dirt, grass and other sundries in the gap 303, improve the flexibility of operation, and reduce the situation that the rollers 302 are stuck and cause the rollers 302 to slip and grind the grass.

[0117] In some embodiments, the omni-directional wheel includes a fixed part 304, the wheel disc 301 is connected to the fixed part 304 and is located in the circumferential direction of the fixed part 304. The fixed part 304 is provided with an opening 304a, the omni-directional wheel located on the outer side includes an end cover 305, the end cover 305 is connected to the fixed part 304 and forms a receiving part 306, the third driving member 421 passes through the opening 304a and is fixed in the receiving part 306.

[0118] In some embodiments, the center of one of the third wheel bodies 31 is a1, the center of the other third wheel body 31 is a2, the line connecting a1 and the rotation center A is B1, and the line connecting a2 and the rotation center A is B2. The length of B2 is greater than the length of B1, so under the same torque, the moment of the third wheel body 31 center a1 is greater because the force arm of B2 is longer. Therefore, when the roller 302 of one of the third wheel bodies 31 is in contact with the ground, the force arm is B1, and when the roller 302 of the other third wheel body 31 is in contact with the ground, the force arm is B2. Therefore, because the rollers 302 on the third wheel bodies 31 are arranged at intervals along the circumferential direction of the third wheel bodies 31, the force arm of the third wheel bodies 31 alternately and periodically changes between B1 and B2, and the third wheel bodies 31 generate different moments under different force arms. When the roller 302 of one of the third wheel bodies 31 is in contact with the ground, the static friction cannot be broken, but when the roller 302 of the other third wheel body 31 is in contact with the ground, the moment increases, which can break the static friction and convert it into sliding friction on the rotation path.

[0119] In some embodiments, the second wheel group 30 includes two fourth wheel bodies 32, which are omnidirectional wheels and have the same effect as the two third wheel bodies 31 described above, and will not be described again here.

[0120] Due to the difference in growth of different areas of the grassland, the height of the grass of the grassland is uneven. Taking the first wheel set 20 as the driving wheel and the second wheel set 30 as the omni-directional wheel as an example, when the self-moving device 100 rotates, if the third wheel body 31 and the fourth wheel body 32 side appear higher grass, the rolling 302 rotation resistance increases, the rolling 302 is easy to be stuck and slide with the grass surface, at this time, the torque required by the first wheel body 21 and the second wheel body 22 increases, and it is easy to break through the static friction and slip, and when the first wheel body 21 and the second wheel body 22 are on the grass surface, the friction between the first wheel body 21 and the second wheel body 22 and the grass surface decreases, and it is more likely to slip and grind the grass. The first driving module 41 is connected with the first wheel set 20, and the second driving module 42 is connected with the second wheel set 30, part of the torque for driving the self-moving device 100 to turn is distributed to the second wheel set 30, the torque required by the first wheel set 20 is reduced, the static friction between the first wheel set 20 and the grass surface is not easy to break through, and the slipping and grinding of the first wheel set 20 are reduced. When the second driving module 42 drives the wheel disc 301 to rotate around the axis of the omni-directional wheel, the plurality of rollers 302 are in turn in contact with the grass surface, the rollers 302 can rotate around their own axes, and by switching different rollers 302 to contact the ground, the situation that the rollers 302 are stuck and slide with the grass surface is reduced, which is conducive to reducing the situation that the rollers 302 slip with the grass surface and causing damage to the lawn. Because the sliding friction is greater than the rolling friction, when the rollers 302 do not slip, the friction that the first wheel body 21 and the second wheel body 22 need to overcome is reduced, the torque that the first wheel body 21 and the second wheel body 22 need to output is smaller, and the static friction between the first wheel body 21 and the second wheel body 22 and the grass surface is not easy to break through. Therefore, the situation that the first wheel body 21 and the second wheel body 22 are ground and the grass is reduced, and the damage to the lawn is reduced. Moreover, the load of the driving wheel is greater than that of the omni-directional wheel, the friction between the driving wheel and the ground is increased, the upper limit of the driving wheel's grip is improved, and the situation that the driving wheel slips and grinds the grass due to insufficient friction provided by the ground is reduced. By placing the center of gravity of the self-moving device 100 close to the driving wheel, the friction between the driving wheel and the ground is increased, the upper limit of the driving wheel's grip is improved, the situation that the driving wheel slips and grinds the grass due to insufficient friction provided by the ground is further reduced, and the damage to the lawn is further reduced. When working on some grassy work surfaces with slopes, the center of gravity is close to the driving wheel, and the driving wheel does not need to provide more driving force to realize the self-moving device 100 rotating in place along the minimum radius, improve the rotation efficiency, reduce the situation that the driving wheel slips and grinds the grass and fails to turn, and reduce the power consumption of the self-moving device 100 and improve the endurance.

[0121] Those skilled in the art will recognize that the above-described embodiments are merely intended to be illustrative of the present application and should not be construed as limiting the present application in any way. As such, those skilled in the art will recognize that, within the scope of the present application, changes and modifications can be made to the above-described embodiments, and where such changes and modifications do not depart from the spirit and scope of the present application, they should be construed as within the scope of the present application.

Claims

1. A self-moving device, wherein, The self-moving device comprises: a frame; a first wheel set and a second wheel set arranged in a first direction, the first wheel set and the second wheel set being connected to the frame; a driving module connected to the first wheel set and the second wheel set; the first wheel set is one of a driving wheel and an omni-directional wheel, and the second wheel set is the other one of the driving wheel and the omni-directional wheel; a load of the driving wheel is greater than a load of the omni-directional wheel.

2. The self-mobiling device of claim 1, wherein, In the first direction, a center of gravity of the self-moving device is located between the first wheel set and the second wheel set, and is closer to the driving wheel.

3. The self-moving device of claim 2, wherein, A rotation center of the self-moving device is located on a straight line passing through an axle of the driving wheel.

4. The self-mobbling device of claim 3, wherein, In the first direction, a distance between the center of gravity and the rotation center is less than a distance between the center of gravity and the omni-directional wheel.

5. The self-mobility device of claim 3, wherein, The driving module comprises a first driving module and a second driving module. The first wheel set comprises a first wheel body and a second wheel body arranged in a second direction, the second wheel set comprises a third wheel body and a fourth wheel body arranged in the second direction, and the first direction is perpendicular to the second direction. The first driving module is connected to the first wheel body and the third wheel body, and the second driving module is connected to the second wheel body and the fourth wheel body.

6. The self-mobbling device of claim 3, wherein, The self-moving device turns in place along a minimum radius, the first wheel body and the third wheel body rotate in the same direction, and the second wheel body and the fourth wheel body rotate in a direction opposite to that of the first wheel body. The second driving module comprises a third driving member connected to the third wheel body, and a traction force on the third wheel body is perpendicular to an axis of the third driving member. A line connecting the rotation center and a center of the third wheel body is defined as a first line, a traction component force of the second driving module on the third wheel body is perpendicular to the first line and points to a rotation direction of the self-moving device.

7. The self-mobility device of claim 5 or 6, wherein, A direction of the traction force forms a first included angle with an extension direction of the first line, and the first included angle is negatively correlated with the traction component force on the third wheel body.

8. The self-mobility device of claim 5, wherein, The second driving module comprises a fourth driving member connected to the fourth wheel body, and a traction force on the fourth wheel body is perpendicular to an axis of the fourth driving member. A line connecting the rotation center and a center of the fourth wheel body is defined as a second line, a traction component force of the second driving module on the fourth wheel body is perpendicular to the second line and points to the rotation direction of the self-moving device. A direction of the traction force forms a second included angle with an extension direction of the second line, and the second included angle is positively correlated with the traction component force on the fourth wheel body.

9. The self-moving device of claim 5, wherein, ​ ​ ​ 10. The self-mobility device of claim 5, wherein, The omni-directional wheel comprises a wheel disc and a plurality of rollers fixed to the outer periphery of the wheel disc, the driving module drives the wheel disc to rotate around the axis of the omni-directional wheel, the plurality of rollers rotate around their own axes, and the axis of the wheel disc is perpendicular to the axis of the rollers.

11. The self-mobility device of claim 10, wherein, The first wheel body and the second wheel body are driving wheels, the third wheel body and the fourth wheel body are omni-directional wheels, the speed of the first wheel body is the same as the speed of the disc of the third wheel body, and the speed of the second wheel body is the same as the speed of the disc of the fourth wheel body.

12. The self-mobility device of claim 11, wherein, The speed of the rollers of the third wheel body is the same as the speed of the rollers of the fourth wheel body.

13. The self-mobility device of claim 11, wherein, The third wheel body comprises two omni-directional wheels, the second driving module passes through one of the omni-directional wheels and is connected to the other omni-directional wheel, and there is a gap between the rollers of adjacent omni-directional wheels.

14. The self-mobility device of claim 1, wherein, The omni-directional wheel comprises one of a continuously-switching wheel and a Mecanum wheel.

15. The self-mobility device of claim 8 or 9, wherein, The self-moving device has a symmetry axis, and the extension direction of the symmetry axis and the extension direction of the traction force form a third included angle γ, 0°≤γ≤45°.

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