Suspension for outdoor robotic tools

Abstract

An outdoor robotic tool comprising a first part and a second part, wherein the first part supports the second part through a suspension arrangement. The suspension arrangement comprises a first component, which comprises at least one magnetic member; and a second component, which comprises at least one magnetic member. The first component is attached to the first part, wherein the second component is attached to the second part, wherein at least one of the magnetic members of suspension arrangement is a permanent magnet; and wherein a magnetic member of the first component is positioned so as to magnetically interact with a magnetic member of the second component when in use. A magnetic field sensing unit may be present that comprises a control unit and a magnetic field sensor. A method for detecting the alignment of the first part relative to the second part, wherein the method comprises detecting the magnetic field using the magnetic field sensing unit.

Claims

1. An outdoor robotic tool comprising a first part and a second part, wherein the first part supports the second part through a suspension arrangement, the suspension arrangement comprising: a) a first component comprising a first magnetic member; and b) a second component comprising a second magnetic member; wherein the first component is attached to the first part, wherein the second component is attached to the second part, wherein at least one of the first and second magnetic members of suspension arrangement is a permanent magnet; and wherein the first magnetic member of the first component is positioned to magnetically interact with the second magnetic member of the second component when in use; wherein the magnetic interaction between the first magnetic member of the first component and the second magnetic member of the second component aligns the first part with the second part in a preferred alignment such that when a force causes the first part and second part to move out of the preferred alignment, the magnetic interaction between the first magnetic member of the first component and the second magnetic member of the second component draws the first part and the second part back into the preferred alignment, wherein the first part defines at least one first contact surface, and wherein the second part defines at least one second contact surface, wherein the at least one first contact surface is in contact with the at least one second contact surface in use, and wherein the at least one first and/or at least one second contact surface comprises a low-friction material.

2. The tool according to claim 1, wherein the tool is a robotic lawnmower.

3. The tool according to claim 1, wherein the second part defines the outer lateral periphery of the tool.

4. The tool according to claim 1, wherein the tool further comprises a magnetic field sensing unit that comprises a control unit and a magnetic field sensor, wherein the magnetic field sensing unit is able to detect a magnetic field of the first magnetic member or the second magnetic member of the suspension arrangement.

5. The tool according to claim 4, wherein the magnetic field sensor is a three dimensional magnetic field sensor.

6. The tool according to claim 1, wherein one or more of the first magnetic member of the first component and the second magnetic member of the second component are designed to interact to attract one another in use.

7. The tool according to claim 1, wherein the permanent magnet is made of a neodymium iron boron (NdFeB) alloy.

8. The tool according to claim 1, wherein one or both of the first and second contact surfaces are textured, and wherein the greater the horizontal displacement from the preferred alignment, the higher the friction between the first and the second contact surfaces is due to a texture pattern of the first and/or second contact surfaces.

9. The tool according to claim 1, wherein the first component and/or the second component additionally comprises a magnet retainer to secure the magnetic member to the first part or the second part of the tool, respectively.

10. The tool according to claim 1, wherein the first and second magnetic members of the suspension arrangement are patterned and/or shaped to produce a non-torus-shaped magnetic field.

11. The tool according to claims 1, wherein the tool performs an action based on a state of the alignment of the first part and the second part and/or a change in the state of alignment of the first part and the second part.

12. The tool according to claim 2, wherein the first part is a chassis of the robotic lawnmower and wherein the second part is a case of the robotic lawnmower.

13. A case for a robotic lawnmower, wherein the case comprises a component, the component comprising at least one magnetic member; wherein the at least one magnetic member is a permanent magnet, and wherein the at least one magnetic member magnetically interacts with a magnetic member of a robotic lawnmower chassis to draw the case into a preferred alignment with the robotic lawnmower chassis, wherein the robotic lawnmower is operated to collide with an object such that the case is brought out of the preferred alignment with the chassis by the collision, and wherein the case is returned to the preferred alignment with the chassis by means of said magnetic interaction.

14. A method for aligning a first part of an outdoor robotic tool relative to a second part of the tool, wherein the method comprises: positioning a first magnetic member of a first component to magnetically interact with a second magnetic member of a second component, in order that the magnetic interaction between the first magnetic member of the first component and the second magnetic member of the second component aligns the first part with the second part in a preferred alignment such that when a force causes the first part and second part to move out of the preferred alignment, the magnetic interaction between the magnetic member of the first component and the magnetic member of the second component draws the first part and the second part back into the preferred alignment; operating the robotic lawnmower to collide with an object such that the case is brought out of the preferred alignment with the chassis by the collision, and returning the case to the preferred alignment with the chassis by means of said magnetic interaction.

15. The method of claim 14, further comprising detecting a state of alignment of the first part of the tool relative to the second part of the tool, wherein the method comprises detecting the magnetic field using a magnetic field sensing unit.

16. The method according to claim 15, further comprising conducting an action via a control unit, wherein the state of alignment of the first part and the second part is detected, and the action is based on a state of alignment.

17. The method according to claim 16, wherein the action is to: a) prevent or cease operation of a cutting unit of the outdoor robotic tool; and/or b) prevent or cease movement of the outdoor robotic tool.

18. The method according to claim 15, wherein a change in the state of alignment of the first part and the second part is detected, and the action is based on the change in the state of the alignment, and wherein the action is to: a) cease operation of a cutting unit of the outdoor robotic tool; b) cease the motion of the outdoor robotic tool; c) log the location of the collision and/or manipulation; or d) control the outdoor robotic tool to change its movement direction, to steer away from an obstacle.

Description

(1) An embodiment of the present invention will now be described with reference to the accompanying drawings, in which:

(2) FIG. 1 is a perspective view of an outdoor robotic tool in accordance with the present invention, specifically a robotic lawnmower, from the top comprising a first part and a second part;

(3) FIG. 2 is a perspective view of the first part depicted in FIG. 1 from the top, where the first part has four first components;

(4) FIG. 3 is a perspective view of the second part depicted in FIG. 1 from the underside, where the second part has four second components;

(5) FIG. 4 is a perspective view of a magnetic field sensing unit comprising a magnetic field sensor;

(6) FIG. 5 is a perspective view of the first part depicted in FIG. 2 from the underside, where the first part has four magnetic field sensing units as depicted in FIG. 4;

(7) FIG. 6 is a perspective view of a cross-section through the outdoor robotic tool depicted in FIG. 1, showing the second part, the suspension arrangement, the first part and the magnetic field sensing unit, wherein the second part is in a preferred arrangement relative to the first part;

(8) FIG. 7 is a cross-section of the outdoor robotic tool depicted in FIG. 1, where the second part has been lifted from the first part, as illustrated by the arrow; and

(9) FIG. 8 is a cross-section of the outdoor robotic tool depicted in FIG. 1, wherein the second part has collided with an object from the right side, as illustrated by the arrow.

(10) Referring firstly to FIG. 1 of the accompanying drawings, there is shown an outdoor robotic tool, specifically a self-propelled, autonomous robotic lawnmower 10, including a first part 20 and a second part 30. The first part 20 may be referred to as a chassis and the second part 30 may be referred to as a case. In this Figure the second part 30 covers the first part 20, as these components would be arranged when the robotic lawnmower 10 is in use. The first part 20 will typically contain cutting blades, wheels for propelling the robotic lawnmower, control circuitry with e.g. navigation electronics, and a power unit for the robotic lawnmower. The second part 30 defines the outer lateral periphery of the tool 10 and will typically protect the robotic lawnmower from damage caused by, for example, collisions and/or the weather.

(11) The first part 20 is shown in more detail in FIG. 2 of the accompanying drawings. The first part 20 has four first components 40. The first components 40 each comprise a magnetic member that comprises a magnet. The magnet is covered by and hidden behind a magnet retainer. In this embodiment, the magnet is a Nd.sub.2Fe.sub.14B magnet. The magnet retainers individually define first contact surfaces for contact with the second part. In this embodiment the first contact surfaces are low in friction. Each magnet retainer is affixed to the first part by three attachments points, which could be screws. The first components 40 are positioned in the corners of the top surface of the first part 20, which allows the second part to be stably supported upon the first part.

(12) The underside of the second part 30 is shown in FIG. 3 of the accompanying drawings. The second part 30 has four second components 50. The second components 50 each comprise a magnetic member that comprises a magnet. The magnet is covered by and hidden behind a magnet retainer. In this embodiment, the magnet is a Nd.sub.2Fe.sub.14B magnet. The magnet retainers of the second components 50 individually define second contact surfaces for contact with the first part. In this embodiment the second contact surfaces are low in friction. Each magnet retainer is affixed to the second part 30 by three attachments points, which could be screws. The second components 50 are positioned in the corners of the inner surface of the second part 30, which allows the second part to be stably supported upon the first part.

(13) In one embodiment, the present invention comprises a magnetic field sensing unit. FIG. 4 of the accompanying drawings shows an exemplary magnetic field sensing unit 60. The magnetic field sensing unit 60 comprises a control unit 61, a sensor board 62 and a sensor board holder 64. The sensor board holder 64 has a first end 66 and a second end 68. The first end 66 is for attachment to the first part 20, for example by a screw, whilst the second end 68 holds the sensor board 62. In this embodiment, the sensor board 62 comprises a 3D Hall Effect sensor.

(14) FIG. 5 of the accompanying drawings shows the underside of the first part 20, to which a magnetic field sensing unit 60 has been provided. The magnetic field sensing unit 60 has four magnetic field sensors, each positioned in a corner of the under surface of the first part 20. In particular, each magnetic field sensor is positioned underneath each first component 40 shown in FIG. 2. One control unit 61 is used with the four magnetic field sensors.

(15) FIG. 6 of the accompanying drawings shows a cross-sectional view through a magnetic field sensing unit 60 and a suspension arrangement, the suspension arrangement comprising second part 30, second component 50, first component 40 and first part 20. In FIG. 6, the suspension arrangement is aligned as it would be in the preferred alignment. The first component 40 comprises a magnet 42 and a magnet retainer 44. The second component 50 comprises a magnet 52 and a magnet retainer 54. The magnet retainer 44 of the first component 40 defines a first contact surface, and the magnet retainer 54 of the second component 50 defines a second contact surface. The first contact surface and the second contact surface are each substantially flat, and in use will be substantially horizontal. The first contact surface makes contact with the second contact surface to hold the second part 30 above the first part 20. The sensor board holder 64 of the magnetic field sensing unit 60 holds the sensor board 62 at a set distance from the magnet 42 of the first component 40.

(16) As can be seen, in the preferred alignment, the magnets 42, 52 are situated above one another, such that their interaction is at a maximum. The Hall Effect sensor on the sensor board 62 will typically be calibrated to the magnetic field at the preferred alignment.

(17) FIGS. 7 and 8 of the accompanying drawings depict the lifting and manipulation of the second part 30 relative to the first part 20 respectively. In each of these figures, the suspension arrangement and the magnetic field sensing unit on the right side (as viewed) are shown in cross-section, whereas the suspension arrangement and the magnetic field sensing unit on the left side (as viewed) are shown in side-on view.

(18) Turning firstly to FIG. 7, the second part 30 is lifted from the first part 20 of the robotic lawnmower 10. It can be seen that the lifting force has exceeded the magnetic interaction of the first components 40 and the second components 50. Therefore, a vertical displacement has been generated between the contact surfaces of the first part 20 and the contact surfaces of the second part 30. The lifting force has caused the first part 20 and the second part 30 to move out of the preferred alignment. The vertical displacement of the first component 40 from the second component 50 has changed the magnetic field at the 3D Hall Effect sensor of the sensor board 62. The magnetic field sensing unit may detect a change in the direction and/or intensity of the magnetic field due to this vertical displacement. The control unit 61 of the magnetic field sensing unit will interpret the data from the Hall Effect sensor and act accordingly, such as to stop the cutting unit of the robotic lawnmower.

(19) Turning now to FIG. 8, the second part 30 has been manipulated relative to the first part 20 of the robotic lawnmower 10. Such a manipulation may occur when the robotic lawnmower 10 is moving autonomously and collides with an object. The force resulting from the collision is shown as an arrow. It can be seen that the force has caused the second part 30 to move leftwards (as viewed) in relation to the first part Therefore, the contact surfaces of the second part 30 have been displaced leftwards in relation to the contact surfaces of the first part 20. The manipulation force has caused the first part 20 and the second part 30 to move out of the preferred alignment. The horizontal displacement of the first component 40 from the second component 50 has changed the magnetic field at the 3D Hall Effect sensor of the sensor board 62. The magnetic field sensing unit may detect a change in the direction and/or intensity of the magnetic field due to this horizontal displacement. The control unit 61 of the magnetic field sensing unit will interpret the data from the Hall Effect sensor and act accordingly, such as to stop the motion of the robotic lawnmower and/or to log the location of the manipulation.