SE2151264A1 - Robotic lawn mower - Google Patents

Abstract

A robotic lawn mower (1) comprises a hand control (5) and a microcontroller unit (14). The hand control (5) is translatable between a first and a second position in a single plane. In the first position, operation of a first function of the robotic lawn mower (1) by manual actuation of the hand control (5) in a direction across the single plane is enabled. In the second position operation of the first function of the robotic lawn mower (1) by manual actuation of the hand control (5) is disabled.

Description

ROBOTIC LAWN MOWER Field of the invention The present invention relates to a robotic lawn mower comprising a hand control and a microcontroller unit.

Background SE 540 586 C2 discloses an outdoor robotic tool comprising a carry handle and a stop button. When the carry handle is raised, the stop button is activated and the stop button may only be deactivated when the carry handle is lowered. The object is to render the movable parts, such as a cutting disk, temporarily inoperable for an increased safety. However, there may be some problems in that the carry handle must be in a raised position to activate the stop button. Many users would not intuitively raise the carry handle on a robotic tool that is still running in order to stop it.

At the same time, the safety in making sure that the robotic tool is always stopped when it is carried by the handle is appreciated. An alternative way of making sure that the robotic tool remains inoperable when carried is needed.

Summafl lt is an object of the present invention to solve, or at least mitigate, parts or all of the above-mentioned problems. To this end, there is provided a robotic lawn mower wherein the hand control is translatable between a first and a second position in a single plane, and in the first position, operation of a first function of the robotic lawn mower by manual actuation of the hand control in a direction across the single plane is enabled; in the second position operation of the first function of the robotic lawn mower by manual actuation of the hand control is disabled.

Hereby the robotic lawn mower may have at least three states, where at least one is disabling all functions of the robotic lawn mower, so that it may be carried without any risk of injury to the user. The two other states may be a working state and a stand-by state, respectively. ln one embodiment the hand control is disconnected from the microcontroller unit in the second position. ln some embodiments the disconnection is realized by an actuator arranged in the hand control being out of range from a coil arranged in the microcontroller. ln further embodiments the hand control is mechanically locked in a direction across the single plane in the second position.

Hereby the hand control in the second position may not be used as a button for start and stop of the robotic lawn mower. ln fact, the lawn mower may not be started at all with the hand control in the second position, which is a "safe position". ln even further embodiments, the hand control forms a carrier handle, for lifting and carrying the robotic lawn mower, in the second position.

With the hand control in the second position, the robotic lawn mower is not only disabled, so that it is safe to carry, the hand control actually forms a carrier handle, by which the robotic lawn mower may intuitively be carried. Thereby the risk that the user may try to lift the robotic lawn mower without disabling it first is reduced, since the disabling of the working state takes place simultaneously with the extension of the handle. ln still further embodiments, the hand control extends inside the outer circumference of the robotic lawn mower in the direction of the single plane in the first position. ln some embodiments the hand control extends a distance across the single plane in the first position, i. e. the hand control takes the form of a slightly raised start/stop button. ln some embodiments the first function in the first position is an on/off function. ln the second position of the hand control, the first function may be disabled, which means that the robotic lawn mower may be switched on only when the hand control is in the first position. When the hand control is in the second position, it is impossible to start the robotic lawn mower, and this position may hence be designated as a safe position for moving the robotic lawn mower or performing work thereon. Starting the robotic lawn mower may be possible only when the hand control is in the first position, i. e. an operating position. ln further embodiments the hand control and the microcontroller unit are coupled by a contactless coupling means. ln some embodiments the contact coupling means is a proximity sensor, which may comprise a capacitive coupling of an LC circuit and the hand control. ln some embodiments the proximity sensor may comprise an inductive coupling of a Hall sensor and the hand control. ln still further embodiments, at least three positions of the hand control are discernible: the first position with a non-actuation of the first function, the first position with an actuation of the first function, and the second position.

Hereby there may be start and stop of the work when the hand control is in the first position, and a disablement of the work when the hand control is in the second position. ln even further embodiments, the hand control is arranged in a housing of the robotic lawn mower, and the microcontroller unit is arranged in the chassis of the robotic lawn mower.

Hereby the microcontroller may be protected from dirt, humidity etc. by an encapsulation. ln some embodiments a leaf spring is arranged in contact with a bar connected to the hand control, to separate the first and second positions of the hand control and to provide a resilience when the hand control is actuated across the single plane in the first position, and an outer, free end of the leaf spring has a bend providing a resistance to transitions in the single plane between the first and second positions, and an inner, flexible portion providing a resistance to the actuation across the single plane. ln some embodiments, the leaf spring extends approximately along a radius of the robotic lawn mower, transversally to the hand control. Hereby the first position is 3 created when the hand control is positioned inside the bend on the leaf spring, i. e. nearer the center of the robotic lawn mower. The hand control may then be in contact with the inner, flexible portion, next to an anchoring portion, which is fastened to the housing or the chassis of the robotic lawn mower.

The inner, flexible portion may be a flat portion, in some embodiments arranged with an upwards inclination, as seen from the anchoring portion. The flexible portion provides a resilience, when the hand control is actuated across the single plane, i. e. when the hand control is pressed for start/stop of the robotic lawn mower. Radially outwards from the flexible portion, the leaf spring transitions into a bend, which serves as a resistance against a motion between the first and second positions. ln some embodiments the bend has the approximate shape of half of a sine wave, half a circle, or half an oval. When the hand control is forced to perform a translational motion in the single plane, it may press against the side of the bend, and the leaf spring may flex in its flexible portion to permit a motion of the hand control from the first to the second position, or vice versa. ln still further embodiments, the hand control comprises a metal body, arranged to be sensed by an LC circuit in the microcontroller unit in the first position of the hand control.

Hereby one type of contactless switch may be obtained. When the metal body in the hand control is sufficiently close to the LC circuit in the microcontroller unit, i. e. when the hand control is pressed, and used as a start/stop button in the first position, a control signal may be created in the LC circuit for controlling the start/stop function. ln the second position of the hand control, the metal body is out of range of the LC circuit, and the start/stop function may be disabled. ln some embodiments the single plane is approximately parallel with a ground surface whereon the robotic lawn mower is placed. ln fact, the single plane is in many embodiments approximately parallel with the general plane of extension of the robotic lawn mower. Also, if the mower is placed on an even, approximately horizontal ground surface, the single plane may be approximately horizontal, and the direction of actuation of the hand control in the first position may be approximately vertical. ln some embodiments the metal body is removable from the hand control in the second position thereof, thereby disabling operation of the robotic lawn mower.

Hereby operation of the robotic lawn mower is entirely disabled, even if the hand control is brought to the first position. Actuation may be impossible since the metal body may no longer be sensed by the contactless sensor in the microcontroller unit. ln further embodiments an outer shape of the robotic lawn mower is approximately circular, and a pair of drive wheels are arranged on a diameter line thereof with a cutting disc arranged between the drive wheels.

Hereby a well-balanced robotic lawn mower may be obtained. The cutting disc is placed approximately at the center of the mower, making cutting of the edges even, regardless of the drive direction of the mower. ln even further embodiments, the hand control is arranged on a circumferential side thereof.

Hereby the top surface, or at least a large part thereof, of the robotic lawn mower may be kept free from controls, handles, displays, etc. to provide room for solar cells or the like. ln still further embodiments, a castor wheel is arranged below the single plane, approximately in register with the hand control.

Hereby the weight of the robotic lawn mower may be distributed on more than the drive wheels. Also, the robotic lawn mower may be balanced and able to support the manual actuation ofthe hand control in a direction across the single plane, i. e. the pressure on the start/stop button. ln further embodiments the castor wheel extends outside of the circumference of the robotic lawn mower in a position of use. ln some embodiments the castor wheel is arranged on an extendable or foldable arm. lt is noted that embodiments of the invention may be embodied by all possible combinations of features recited in the claims. Further, it will be appreciated that the various embodiments described for the device are all combinable with the method as defined in accordance with the second aspect of the present invention, and vice versa. Brief description of the drawinqs The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non- limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein: Fig. 1 is a diagrammatic view in perspective of a robotic lawn mower according to the disclosure; Fig. 2a is a diagrammatic view in perspective of a housing of the robotic lawn mower of Fig. 1, with a hand control in a first position and a non-actuated state; Fig. 2b is a view according to Fig. 2a, with the hand control in an actuated state; Fig. 2c is a view according to Figs. 2a and 2b, with the hand control in a second position; Fig. 3a is a partially sectional view in perspective of the housing, including an enlargement ofa part thereof, with the hand control in the first position; Fig. 3b a view according to that of Fig. 3b, with the hand control in the second position; and Fig. 4 is a partially sectional view in perspective of the housing and the chassis of the robotic lawn mower.

All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the embodiments, wherein other parts may be omitted. Detailed description of the exemplarv embodiments Fig. 1 illustrates a robotic lawn mower 1, comprising a housing 2 and a chassis 3. ln the disclosed embodiment, the robotic lawn mower 1 is provided with two drive wheels 4, arranged at either side of the robotic lawn mower 1. The drive wheels 4 are preferably arranged on a diameter line passing through the center of the robotic lawn mower 1. A cutting disc (not visible in the drawings) is preferably arranged between the drive wheels 4. A cutting disc and drive wheels 4 according to prior art, well known by the skilled person, may be useful in some embodiments of the disclosure.

A hand control 5 is arranged at an outer edge section of the housing 2. The hand control 5 may be utilized for several purposes, including start of the robotic lawn mower 1, and its positions and functions will be described in greater detail below.

A castor wheel 6 is arranged below the hand control 5. The weight of the robotic lawn mower 1 may preferably be distributed so that its opposite end is kept at a level where it is not accidentally dragged along the ground, when traveling over minor bumps or inclinations. The castor wheel 6 may also be useful for counteracting a motion downwards of the robotic work tool 1 when the hand control 5 is pressed downwards. ln some embodiments, the hand control 5 and the castor wheel 6 are arranged at the front of the robotic lawn mower 1, i. e. at the edge section, which is normally facing forward, when the robotic lawn mower 1 is moving in its normal direction of travel.

Fig. 2a shows the housing 2 with the hand control 5 in a first position at the edge of the housing 2. This position is a basic position during operation, i. e. lawn mowing. An outer edge of the hand control 5 conforms with the outer edge of the housing 2, i. e. the hand control 5 extends only inside of the circumference of the 7 housing 2. The robotic lawn mower 1 is hence compact, and the risk of any parts thereof bumping or snagging into uncut grass, shrubbery, or rocks is minimized. The hand control 5 also extends some distance above the general plane of the top of the housing 2, and there is an open space 7 directly below the hand control 5. Hence there is sufficient room for a movement downwards of the hand control 5. ln the disclosed embodiment there are no other controls on the housing 2, which presents a smooth and planar top surface. The top surface may be used e. g. for decorative purposes, for solar cells, or for carrying additional, optional equipment or accessories. ln Fig. 2b the hand control 5 has been pressed down, in a direction across the general plane of extension of the robotic lawn mower 1. lt has not been moved in a direction within the plane. The upper surface ofthe hand control 5 is approximately level with the top surface of the housing 2. lts bottom may then be approximately level with the bottom of the open space 7. The hand control 5 may not stay in its pressed down position, but may, in a preferred embodiment, spring back to the position shown in Fig. 2a. By the pressing of the hand control 5, actuation of a first function, e. g. start of the robotic lawn mower 1, may be accomplished. By a repeated pressing of the hand control 5 a second function, e. g. stop of the robotic lawn mower 1, may be actuated. ln a preferred embodiment, the actuation of a function is hence dependent on the present function. ln other words, if the robotic lawn mower 1 is already started, the next pressing of the hand control 5, may stop it, and vice versa.

Fig. 2c shows the hand control 5 in a second position, after it has performed a translational movement in a single plane from the position shown in Fig. 2a. The hand control 5 is now blocked from movements across the single plane wherein the translational movement is performed. Also, there is a mechanical resistance against moving the hand control 5 back to the first position from the second position, and vice versa. Hence, the hand control 5 may tend to remain in its present position, whichever that position is. ln a preferred embodiment, which may be seen in Fig. 2c, the hand control 5 may be used as a handle for carrying the robotic lawn mower 1, and it is designed for this purpose, by being sturdy enough to withstand the weight of the robotic lawn mower 1 without breaking, and by being of a size and shape to fit the hand of an 8 adult user. A particular advantage with integrating the hand control 5 with a handle is that the start function is automatically disabled when the hand control 5 is pulled out to serve as a handle. This is both practical and safe for the user. The user need not bother with actuating more than one control, and it is impossible to lift the robotic lawn mower 1 by the handle 5 without disabling the cutting function.

The partially sectional views of Figs. 3a and 3b disclose one possibility of achieving the two distinct positions of the hand control 5. The hand control 5 is mechanically connected to an inner bar 8, which is slidably arranged along a track 15 in the housing 2. The sliding motion of the hand control 5 and the bar 8 takes place in a single plane, and the first and second positions of the hand control 5 may be attained. A pressing force on the hand control 5 across the single plane may be propagated to the bar 8, which is in contact with a leaf spring 9. The leaf spring 9 has an inner, flexible portion 10. ln Fig. 3a, when the hand control 5 is arranged in its first position, as described above with reference to Figs. 2a-b, the bar 8 contacts the leaf spring 9 at its flexible portion 10. The pressing motion across the single plane results in a reactive motion in the opposite direction by the spring action, which has the effect of returning the hand control 5 to its original position. ln Fig. 3b, when the hand control 5 is pulled out to its second position, as described above with reference to fig. 2c, the bar 8 is also pulled in the same direction. From the position in contact with the flexible portion 10 of the leaf spring 9, the bar may be pressed against an inner side of a bend 11 of the leaf spring 9. The leaf spring 9 may flex downwards by the sideways contact force applied on the bend 11, and the bar 8 may pass the bend 11 with some resistance. This resistance serves to provide two distinct positions of the hand control 5. lt may be noted that in some embodiments more than two distinct positions may be provided in a similar manner, by providing the leaf spring 9 with two or more bends 11 in its longitudinal direction.

When the bar 8 has been pulled so far that it has passed the bend 11, the hand control 5 has reached its second position, outside the circumference of the housing 2, as shown in Figs. 2c and 3b. ln this position it is useful as a handle, and the actuation of the start/stop function is disabled. ln fig. 4, the start/stop function of the hand control 5 in the first position is illustrated in an explanatory manner. A metal body 12 is arranged inside the hand control 5, and a proximity sensor 13; in some embodiments a coil and in some embodiments a Hall sensor, is arranged on a printed circuit board (PCB) 14, which constitutes the microcontroller unit. The microcontroller unit 14 is arranged in the chassis 3 beneath the hand control 5.

The disablement of the start/stop function in the second position is not only the result of the loss of contact between the leaf spring 9 and the bar 8, which means that the movement across the single plane, wherein the hand control 5 is translatable, is no longer possible. The hand control 5 is also outside of the circumference of the housing 2, and hereby out of range of the microcontroller unit 14 of the robotic lawn mower 1.

When the hand control 5 is positioned directly above the sensor 13 in the first position, the sensor 13 may register the presence of the metal body 12, when the hand control 5 is pressed down in a direction across the single plane of translation, and an actuation signal may be produced for starting the robotic lawn mower 1 if it is stopped and vice versa. After the presence of the metal body 12 has been registered and the actuation signal has been produced, the leaf spring 9 may return the hand control 5 to its original position by spring action. ln the second position of the hand control 5, the metal body 12 may be out of range of the sensor 13, even if the hand control 5 were to be mobile across the single plane of translation. ln some embodiments, the metal body 12 may be removable from the hand control 5, thereby disabling the robotic lawn mower 1 from being started, regardless of the position of the hand control 5, until the metal body 12 is repositioned. Hereby an unauthorized start of the robotic lawn mower 1 may be prevented. ln some embodiments the metal body 12 and the proximity sensor 13 may be matched, so that the robotic lawn mower 1 may be started only with the associated metal body 12, and theft of the robotic lawn mower 1 may be discouraged.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. ln the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. 11

Claims (1)

1.Claims _ Robotic lawn mower (1) comprising a hand control (5) and a microcontroller unit (14) wherein the hand control (5) is translatable between a first and a second position in a single plane, and in the first position, operation of a first function of the robotic lawn mower (1) by manual actuation of the hand control (5) in a direction across the single plane is enabled; in the second position operation ofthe first function of the robotic lawn mower (1) by manual actuation of the hand control (5) is disabled. _ Robotic lawn mower (1) according to claim 1, wherein the hand control (5) in the second position is disconnected from the microcontroller unit (14). _ Robotic lawn mower (1) according to claim 1 or claim 2, wherein the hand control (5) in the second position is mechanically locked in a direction across the single plane. _ Robotic lawn mower (1) according to any of claims 1 to 3, wherein the hand control (5) forms a carrier handle, for lifting and carrying the robotic lawn mower (1), in the second position. _ Robotic lawn mower (1) according to any of claims 1 to 4, wherein the hand control (5) extends inside the outer circumference of the robotic lawn mower (1) in the direction of the single plane in the first position. _ Robotic lawn mower (1) according to any of claims 1 to 5, wherein the first function in the first position is an on/off function. _ Robotic lawn mower (1) according to any of the preceding claims, wherein the hand control (5) and the microcontroller unit (14) are coupled by a contactless coupling means (12, 13). _ Robotic lawn mower (1) according to any of the preceding claims, wherein at least three positions of the hand control (5) are discernible: the first position with a non-actuation of the first function, the first position with an actuation of the first function, and the second position.9. Robotic lawn mower (1) according to any of the preceding claims, wherein the hand control (5) is arranged in a housing (2) of the robotic lawn mower (1), and the microcontroller unit (14) is arranged in the chassis (3) of the robotic lawn mower (1). 10. Robotic lawn mower (1) according to any of the preceding claims, wherein a leaf spring (9) is arranged in contact with a bar (8) connected to the hand control (5), to separate the first and second positions of the hand control (5) and to provide a resilience when the hand control (5) is actuated across the single plane in the first position, and an outer, free end of the leaf spring (9) has a bend (11) providing a resistance to transitions in the single plane between the first and second positions, and an inner, flexible portion (10) providing a resistance to the actuation across the single plane. 11.Robotic lawn mower (1) according to any of the preceding claims, wherein the hand control (5) comprises a metal body (12), arranged to be sensed by an LC circuit (13) in the microcontroller unit (14) in the first position of the hand control (5). 12. Robotic lawn mower (1) according to any of the preceding claims, wherein the single plane is approximately parallel with a ground surface whereon the robotic lawn mower (1) is placed. 13.Robotic lawn mower (1) according to claim 11, wherein the metal body (12) is removable from the hand control (5) in the second position thereof, thereby disabling operation of the robotic lawn mower (1 ). 14. Robotic lawn mower (1) according to any of the preceding claims, wherein an outer shape of the robotic lawn mower (1) is approximately circular, and a pair of drive wheels (4) are arranged on a diameter line thereof with a cutting disc arranged between the drive wheels (4). 15. Robotic lawn mower (1) according to any of the preceding claims, wherein the hand control (5) is arranged on a circumferential side thereof.16. Robotic lawn mower (1) according to any of the preceding claims, wherein a castor wheel (6) is arranged below the single plane, approximately in register with the hand control (5). 17.Robotic lawn mower (1) according to claim 16, wherein the castorwheel (6) extends outside of the circumference of the robotic lawn mower (1) in a position of use. 14