Robotic cleaning device

Abstract

A robotic cleaning device having a main body, at least one drive wheel, at least one linking member rotationally coupled to the main body about a suspension axis and rotationally supporting the at least one drive wheel about a drive wheel axis such that at least a section of the main body can be raised from a lowered position, closer to the ground surface, to a raised position, further away from the ground surface. First and second spring members are arranged to provide a moment on the linking member about the suspension axis in the first direction to press the at least one drive wheel towards the ground surface. The moment provided by the first spring member is higher in the lowered position than in the raised position and the moment provided by the second spring member is higher in the raised position than in the lowered position.

Claims

1. A robotic cleaning device comprising: a main body; at least one drive wheel for driving the robotic cleaning device on a horizontal ground surface; at least one linking member rotationally coupled to the main body about a suspension axis and rotationally supporting the at least one drive wheel about a drive wheel axis such that by rotating the linking member about the suspension axis in a first direction, at least a section of the main body can be raised from a lowered position, closer to the ground surface, to a raised position, further away from the ground surface; and a first spring member and a second spring member each arranged to provide a moment on the linking member about the suspension axis in the first direction to press the at least one drive wheel towards the ground surface; wherein the moment provided by the first spring member is higher in the lowered position than in the raised position and the moment provided by the second spring member is higher in the raised position than in the lowered position.

2. The robotic cleaning device according to claim 1, wherein the first spring member comprises a tension spring.

3. The robotic cleaning device according to claim 1, wherein the second spring member comprises a cantilever spring biased against the linking member.

4. The robotic cleaning device according to claim 3, wherein the second spring member comprises a fixed section and a free section, wherein the fixed section is fixed with respect to the main body and the free section is biased against the linking member.

5. The robotic cleaning device according to claim 4, wherein the linking member comprises a cam profile engaged at a second spring engagement point by the free section of the second spring member.

6. The robotic cleaning device according to claim 5, wherein the drive wheel axis is positioned vertically between the second spring engagement point and the suspension axis in the lowered position and the suspension axis is positioned vertically between the second spring engagement point and the drive wheel axis in the raised position.

7. The robotic cleaning device according to claim 5, wherein the suspension axis and the second spring engagement point are substantially horizontally aligned in the lowered position and the second spring engagement point is positioned horizontally between the suspension axis and the drive wheel axis in the raised position.

8. The robotic cleaning device according to claim 3, wherein a moment arm of the free section of the second spring member biased against the linking member acting on the suspension axis is substantially zero when the main body is in the lowered position.

9. The robotic cleaning device according to claim 3, wherein the first spring member and the second spring member are substantially aligned in the lowered position and/or the raised position.

10. The robotic cleaning device according to claim 3, wherein the first spring member and the second spring member are substantially aligned with an upper edge of the linking member in the lowered position.

11. The robotic cleaning device according to claim 3, wherein the first spring member and the second spring member are oriented substantially parallel with the ground surface in the lowered position and/or the raised position.

12. The robotic cleaning device according to claim 1, wherein the first spring member is attached to the linking member at a first spring engagement point and wherein the drive wheel axis is positioned vertically between the first spring engagement point and the suspension axis in the lowered position and the suspension axis is positioned vertically between the first spring engagement point and the drive wheel axis the raised position.

13. The robotic cleaning device according to claim 1, wherein the first spring member is attached to the linking member at a first spring engagement point and wherein the suspension axis is positioned horizontally between the first spring engagement point and the drive wheel axis in the lowered position and the first spring engagement point is positioned horizontally between the suspension axis and the drive wheel axis in the raised position.

14. The robotic cleaning device according to claim 1, wherein the first spring member is attached to the linking member at a first spring engagement point and wherein the suspension axis and the first spring engagement point are substantially horizontally aligned in the lowered position and the first spring engagement point positioned horizontally between the suspension axis and the drive wheel axis in the raised position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:

(2) FIG. 1: schematically represents a front view of a robotic cleaning device in a lowered position;

(3) FIG. 2: schematically represents a bottom view of the robotic cleaning device;

(4) FIG. 3: schematically represents a front perspective view of a drive wheel assembly of the robotic cleaning device in the lowered position;

(5) FIG. 4: schematically represents a rear perspective view of the drive wheel assembly in the lowered position;

(6) FIG. 5: schematically represents a front perspective view of the drive wheel assembly in a raised position;

(7) FIG. 6: schematically represents a rear perspective view of the drive wheel assembly in the raised position;

(8) FIG. 7: schematically represents a side view of the drive wheel assembly in the lowered position; and

(9) FIG. 8: schematically represents a side view of the drive wheel assembly in the raised position.

DETAILED DESCRIPTION

(10) In the following, a robotic cleaning device comprising at least one drive wheel and a first and second spring member associated with the at least one drive wheel will be described.

(11) The same reference numerals will be used to denote the same or similar structural features.

(12) FIG. 1 schematically represents a front view of a robotic cleaning device 10 in a lowered position. The robotic cleaning device 10 comprises two drive wheels 12 for driving the robotic cleaning device 10 over a surface 14 to be cleaned and a main body 16. The clearance between the main body 16 and the surface 14 may be adjusted as will be described in the following.

(13) The drive wheels 12 may be driven jointly to drive the robotic cleaning device 10 in a forward travel direction or in a backward direction, or independently to turn the robotic cleaning device 10. For example, one drive wheel 12 may be driven forwards and the other drive wheel 12 may be driven backwards in order to turn the robotic cleaning device 10 substantially on the spot or one drive wheel 12 may be driven forwards and the other drive wheel 12 may be locked in order to turn the robotic cleaning device 10 around the stationary drive wheel 12.

(14) The robotic cleaning device 10 optionally comprises a rotatable brush roll 18 arranged horizontally at its front to enhance the dust and debris collecting properties of the robotic cleaning device 10. The robotic cleaning device 10 may further optionally comprise a 3D sensor system comprising a camera 20 and two line lasers 22, 24, which may be horizontally or vertically oriented line lasers.

(15) FIG. 2 schematically represents a bottom view of the robotic cleaning device 10. As can be seen in FIG. 2, the main body 16 has a substantially triangular appearance parallel with the horizontal ground surface 14 and has a substantially straight side facing in a forward travel direction 26 of the robotic cleaning device 10. At the rear portion of the main body 16, a caster wheel 28 is disposed to support a rearward portion of the main body 16. In this implementation, the caster wheel 28 is arranged to swivel about a vertical axis.

(16) The robotic cleaning device 10 further comprises two wheel motors 30, one associated with each drive wheel 12, to rotationally drive the respective drive wheel 12 and a control unit 32 to control the drive of the respective wheel motor 30. Various different types of transmissions may be used in order to transmit a driving force from the wheel motor 30 to the drive wheel 12, such as a gear transmission or a belt transmission.

(17) FIG. 2 further shows that the robotic cleaning device 10 may comprise, a rotatable side brush 34, a suction fan 36 drivable by a fan motor 38 communicatively connected to the control unit 32 from which the fan motor 38 receives instructions for controlling the suction fan 36 and a brush roll motor 40 operatively coupled to the brush roll 18 to control its rotation in line with instructions received from the control unit 32.

(18) FIGS. 3 and 4 schematically represent a front perspective view and a rear perspective view, respectively, of one of two drive wheel assemblies 42 of the robotic cleaning device 10 in the lowered position. The lowered position may for example be adopted when cleaning a hard floor (e.g. parquet) and there are no obstacles to be climbed. In addition to the previously mentioned drive wheel 12 and wheel motor 30, the drive wheel assembly 42 comprises a linking member 44, a first spring member 46 and a second spring member 48. The linking member 44 is pivotally connected to the main body 16 and rotationally supports the drive wheel 12.

(19) In the following, the first spring member 46 is exemplified as a tension spring and the second spring member 48 is exemplified as a cantilever spring in the form of a blade spring. However, these types of springs are not essential for the general function to provide a pressing force on the drive wheel 12 in both the lowered position and in the raised position.

(20) The first spring member 46 is connected between the main body 16 and the linking member 44. The attachment point between the first spring member 46 and the linking member 44 is referred to as a first spring engagement point 50. The second spring member 48 comprises one section fixed with respect to the main body 16 and an opposing free section 52. In the illustrated lowered position, the first spring member 46 is in an extended state to pull the first spring engagement point 50 and the second spring member 48 provides a downwardly acting force on the linking member 44.

(21) Both the first spring member 46 and the second spring member 48 are substantially horizontally aligned and arranged parallel to each other. In the illustrated implementation, both the first spring member 46 and the second spring member 48 are flush with an upper edge of the linking member 44. As can be seen in FIGS. 3 and 4, the first spring member 46 and the second spring member 48 are aligned in a compact arrangement in the lowered position.

(22) FIGS. 5 and 6 schematically represent a front perspective view and a rear perspective view, respectively, of the drive wheel assembly 42 in the raised position. The raised position may be adopted when the robotic cleaning device 10 travels on a thick carpet and/or when climbing an obstacle. In the raised position, the drive wheels 12 of the robotic cleaning device 10 are moved out from the main body 16 and downwards towards the ground surface 14 (e.g. floor).

(23) In this state, the first spring member 46 still pulls the linking member 44 at the first spring engagement point 50. However, since the first spring member 46 is in a less extended state in the illustrated raised position, the force by the first spring member 46 is lower in raised position as compared to the lowered position. The second spring member 48 also provides a downwardly acting force on the linking member 44 in the raised position. Also in the raised position, the first spring member 46 and the second spring member 48 are aligned in a compact arrangement.

(24) FIG. 7 schematically represents a side view of the drive wheel assembly 42 in the lowered position and FIG. 8 schematically represents a side view of the drive wheel assembly 42 in the raised position.

(25) The linking member 44 is rotationally coupled to the main body 16 about a suspension axis 54. The linking member 44 is further arranged to rotationally support the associated drive wheel 12 about a drive wheel axis 56. Both the suspension axis 54 and the drive wheel axis 56 are oriented substantially perpendicular to the forward travel direction 26 of the robotic cleaning device 10. As can be seen in FIGS. 7 and 8, the suspension axis 54 is arranged in front of the drive wheel axis 56, as seen in the forward travel direction 26, and the linking member 44 may therefore be said to constitute a trailing suspension. In the lowered position, a general extension direction of the linking member 44 is substantially parallel with the forward travel direction 26 of the robotic cleaning device 10.

(26) When the linking member 44 is rotated about the suspension axis 54 in a first direction 58, the linking member 44 can be moved from the lowered position, as illustrated in FIG. 7, to the raised position, as illustrated in FIG. 8. The raised position is here constituted by a maximally raised position where the linking member 44 is inclined approximately 45° with respect to the horizontal ground surface 14, but may also be constituted by an intermediate position. Since the suspension axis 54 is raised higher above the horizontal ground surface 14 in the raised position in FIG. 8 than in the lowered position in FIG. 7, also a section of the main body 16, to which the linking member 44 is attached, is raised higher above the horizontal ground surface 14 in the raised position than in the lowered position.

(27) This clearance control may be entirely independent between the two drive wheel assemblies 42 of the robotic cleaning device 10. For example, one linking member 44 may adopt the lowered position while the other linking member 44 adopts the raised position, and vice versa. Of course, both linking members 44 may also simultaneously adopt the lowered position or the raised position.

(28) Since the first spring member 46 is extended in the lowered position in FIG. 7, it generates a force on the first spring engagement point 50, here implemented as an upwardly protruding hook, to which the first spring member 46 is attached. This force acting on the first spring engagement point 50 in turn generates a moment on the linking member 44 about the suspension axis 54 in the first direction 58. Thereby, the first spring member 46 is arranged to provide a moment on the linking member 44 about the suspension axis 54 in the first direction 58 to press the drive wheel 12 downwardly towards the ground surface 14.

(29) In the raised position in FIG. 8 however, the first spring member 46 is less extended in comparison with FIG. 7. As a result, in the raised position, the force acting on the first spring engagement point 50 and the consequential moment acting on the linking member 44 about the suspension axis 54 in the first direction 58 are lower in comparison with the lowered position. The first spring member 46 is thereby arranged to provide a higher moment in the lowered position than in the raised position. More specifically, the first spring member 46 is thereby arranged to provide a first, higher moment on the linking member 44 about the suspension axis 54 in the first direction 58 when the main body 16 is in the lowered position and to provide a second, lower moment on the linking member 44 about the suspension axis 54 in the first direction 58 when the main body 16 is in the raised position.

(30) The second spring member 48 comprises a fixed section 60 that is fixed with respect to the main body 16 and a free section 52 that is biased against the linking member 44. The second spring member 48 is biased downwardly and provides a downward force 62 on a cam profile 64 of the linking member 44. The contact point between the second spring member 48 and the linking member 44 is referred to as a second spring engagement point 66.

(31) As illustrated by a vertical line 68 in FIG. 7, the force 62 by the second spring member 48 acting on the linking member 44 is directed towards the suspension axis 54. As a consequence, in the lowered position, the second spring member 48 does not generate any moment on the linking member 44 about the suspension axis 54.

(32) When the linking member 44 starts to rotate about the suspension axis 54 in the first direction 58, for example if the robotic cleaning device 10 encounters an obstacle so that the impact force from the obstacle on the drive wheel 12 together with the moment provided on the linking member 44 about the suspension axis 54 in the first direction 58 by the first spring member 46 overcomes the gravital force from the main body 16 acting on the drive wheel assembly 42, the second spring engagement point 66 is horizontally displaced (in a backward direction, opposite to the forward travel direction 26) with respect to the suspension axis 54. As a consequence, the downward force 62 from the second spring member 48 acting on the linking member 44 starts to generate a moment on the suspension axis 54 in the first direction 58. The moment arm of this moment is illustrated by the line 70.

(33) In other words, the second spring member 48 is arranged to provide a higher moment on the linking member 44 in the raised position than in the lowered position. More specifically, the second spring member 48 is thereby arranged to provide no moment on the linking member 44 about the suspension axis 54 when the main body 16 is in the lowered position and to provide a moment on the linking member 44 about the suspension axis 54 in the first direction 58 when the main body 16 is in the raised position.

(34) As the linking member 44 rotates about the suspension axis 54 from the lowered position to the raised position, the second spring engagement point 66 travels along the cam profile 64 of the linking member 44. As can be gathered from FIGS. 7 and 8, the cam profile 64 is designed such that the second spring engagement point 66 is substantially maintained in the same horizontal plane with respect to the main body 16 as the linking member 44 rotates about the suspension axis 54. In other words, the second spring member 48 is maintained substantially horizontal and is lifted together with the main body 16 as the main body 16 moves from the lowered position to the raised position, and vice versa.

(35) FIG. 7 shows that the drive wheel axis 56 is positioned vertically between the second spring engagement point 66 and the suspension axis 54 in the lowered position. More specifically, a vertical distance between the suspension axis 54 and drive wheel axis 56 is approximately 40% of the vertical distance between the suspension axis 54 and the second spring engagement point 66 when the linking member 44 adopts the lowered position.

(36) FIG. 8 further shows that the suspension axis 54 is positioned slightly above and vertically between the second spring engagement point 66 and the drive wheel axis 56 in the raised position. More specifically, the vertical distance between the drive wheel axis 56 and the suspension axis 54 is approximately 10% of the vertical distance between the drive wheel axis 56 and the second spring engagement point 66.

(37) FIG. 7 further shows that the suspension axis 54 and the second spring engagement point 66 are horizontally aligned in the lowered position such that no torque is generated about the suspension axis 54 by the second spring member 48 when the linking member 44 is in the lowered position. In other words, the moment arm 70 of the force 62 from the second spring member 48 acting downwardly on the linking member 44, as illustrated in raised position of FIG. 8, is zero, or substantially zero, in the lowered position of FIG. 7.

(38) FIG. 8 further shows that the second spring engagement point 66 is positioned horizontally between the suspension axis 54 and the drive wheel axis 56 in the raised position of the linking member 44. More specifically, the horizontal distance between the suspension axis 54 and the second spring engagement point 66 is approximately 30% of the horizontal distance between the suspension axis 54 and the drive wheel axis 56.

(39) FIG. 7 further shows that the drive wheel axis 56 is positioned vertically between the first spring engagement point 50 and the suspension axis 54 in the lowered position. More specifically, the vertical distance between the suspension axis 54 and the drive wheel axis 56 is approximately 40% of the vertical distance between the suspension axis 54 and the first spring engagement point 50.

(40) FIG. 8 further shows that the suspension axis 54 is positioned vertically between the first spring engagement point 50 and the drive wheel axis 56 in the raised position. More specifically, the vertical distance between the drive wheel axis 56 and the suspension axis 54 is approximately 10% of the vertical distance between the drive wheel axis 56 and the first spring engagement point 50.

(41) FIG. 7 further shows that the suspension axis 54 and the first spring engagement point 50 are substantially horizontally aligned in the lowered position. FIG. 8 further shows that the first spring engagement point 50 is positioned horizontally between the suspension axis 54 and the drive wheel axis 56 in the raised position. More specifically, the horizontal distance between the suspension axis 54 and the first spring engagement point 50 is approximately 50% of the horizontal distance between the suspension axis 54 and the drive wheel axis 56 in the raised position.

(42) The second spring member 48 thus ensures that the drive wheel 12 is pressed downwards against the ground surface 14, with a sufficient force to prevent slippage, also in the raised position where the force generated by the first spring member 46 is reduced. Due to the stronger contact between the drive wheel 12 and the ground surface 14, any navigation by the robotic cleaning device 10 based entirely or partly on odometry is improved. The robotic cleaning device 10 is thus less likely to lose track of its position.

(43) The increased downward force on the drive wheel 12 in the raised position also gives a stronger force to a suction nozzle in the raised position and the robotic cleaning device is thereby less prone to stick to, for example, a carpet.

(44) While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.