SE2050200A1

SE2050200A1 - Lawnmower

Info

Publication number: SE2050200A1
Application number: SE2050200A
Authority: SE
Inventors: Anders Sjögren
Original assignee: Husqvarna Ab
Priority date: 2019-12-04
Filing date: 2020-02-24
Publication date: 2021-06-05
Also published as: SE544974C2; SE544276C2; SE2150080A1

Abstract

A lawnmower (1) is disclosed comprising a lawnmower chassis (3), lawnmower support members (5, 5’) configured to abut against a ground surface (7) in a first plane (P1) during operation of the lawnmower (1), and a cutting unit (9) configured to operate in a cutting plane (PC). The cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) to pivot between a first position and a second position. The angle between the cutting plane (PC) and the first plane (P1) is different when the cutting unit (9) is in the second position than when the cutting unit (9) is in the first position.

Description

Lawnmower TECHNICAL FIELDThe present disclosure relates to a lawnmower, such as a self-propelled autonomous robotic lawnmower.

BACKGROUND Various types of lawnmowers exist on today's market. Examples are walk-behind mowers,riding mowers, and self-propelled robotic lawnmowers. A walk-behind mower is a lawnmowerusually comprising an elongated handle allowing a user to push, and/or to guide, thelawnmower. Some walk-behind mowers comprise a propulsion arrangement configured todrive one or more wheels of the lawnmower. Walk-behind mowers lacking a propulsionarrangement are sometimes referred to as “push mowers”. A riding mower is a mowercomprising a seat for a user, a steering device, such as a steering wheel, and a motorconfigured to provide motive power to the riding mower. Usually, riding mowers are used to mow bigger lawns, gardens, parks, sports fields, golf courts or the like.

A self-propelled robotic lawnmower is a mower capable of cutting grass in areas in anautonomous manner. Some robotic lawnmowers require a user to set up a border wirearound a lawn that defines the area to be mowed. Such robotic lawnmowers use a sensor tolocate the wire and thereby the boundary of the area to be trimmed. ln addition to the wire,robotic lawnmowers may also comprise other types of positioning units and sensors, forexample sensors for detecting an event, such as a collision with an object within the area.The robotic lawnmower may move in a systematic and/or random pattern to ensure that thearea is completely cut. ln some cases, the robotic lawnmower uses the wire to locate arecharging dock used to recharge the one or more batteries. Generally, robotic lawnmowersoperate unattended within the area in which they operate. Examples of such areas are lawns, gardens, parks, sports fields, golf courts and the like.

Some lawnmowers comprise an electric motor configured to rotate the cutting unit and somelawnmowers comprise a combustion engine configured to rotate the cutting unit. The use ofan electric motor provides several advantages over the use of a combustion engine when itcomes to emission levels, noise levels, operational reliability, and the need for service andrepair. However, a problem associated with electrically powered lawnmowers is availableoperational time. Cutting grass requires a lot of energy and in riding mowers and self-propelled robotic lawnmowers, it is usually not practically possible to use a power cord to power the electric motor. Therefore, these types of lawnmowers usually comprise one or 2 more batteries configured to power the electric motor. When such one or more batteries areemptied, they must be recharged or replaced. One solution to prolong the availableoperational time could be to increase the size and/or the number of batteries. However, sucha solution adds weight and costs to the lawnmower and in many cases, these is a practical limit for the size of the batteries of a lawnmower.

Energy consumption and available operational time also constitute problems for lawnmowerscomprising a combustion engine. This because such lawnmowers comprise a tank accommodating fuel, and when such a tank is emptied, it must be replenished.

Furthermore, various types of lawnmowers, such as those described above, are associatedwith some mutual problems. One such problem is cutting result, which can be subdivided intovisual cutting result and uniformity of cutting. The visual cutting result can be defined as thevisual cutting result determined by a person viewing a mowed lawn. The uniformity of thecutting can be defined as uniformity of a length of the grass of a mowed lawn, i.e. if straws ofthe grass in a lawn are cut to a uniform length. So called cutting tracks can be formed Whenmowing a lawn. Cutting tracks are tracks in the lawn having different length of the grass thanportions adjacent to the tracks. Cutting tracks have a negative impact on the cutting result and is especially problematic if the lawnmower is moving in systematic patterns.

Moreover, many lawns have a highly varying length and density of the grass prior to thecutting. That is, some portions of the lawn may have a significantly greater length and densityof the grass than other portions of the lawn. The varying length and density of the grass priorto the cutting may be the result of varying soil qualities of the lawn, varying water levels in thelawn, varying nutrition levels in the lawn, varying illumination levels onto the lawn, varyinggrass types in the lawn, and the like. The cutting unit of a lawnmower will be subjected to agreater load when the lawnmower is reaching a portion of a lawn having greater length anddensity of the grass. The higher load Will slow down an operation speed of the cutting unitand Will increase energy consumption of the lawnmower. Moreover, the higher load mayreduce the cutting result partly due to the slower operation speed of the cutting unit. lnaddition, a too high load on the cutting unit may cause an obstruction of the cutting unit which may stop the cutting unit from operating.

Another problem associated with lawnmowers is build-up of vegetation, such as grass, ontovarious components of the lawnmower. The area of the lawnmower surrounding the cuttingunit is particularly problematic. Firstly, the build-up of vegetation, such as grass, is most common in this area, and secondly, the build-up of grass in this area may significantly 3 increase the energy consumption of the lawnmower and may even cause an obstruction of the cutting unit stopping the cutting unit from operating.

Still another problem associated with lawnmowers is co||ision between the cutting unit andobjects other than grass and softer types of vegetation, such as stumps, stones, sticks, andthe like. Collision between the cutting unit and such objects constitutes a problem becausethe cutting unit, as well as other parts of the lawnmower, may become damaged and/or subjected to premature wear. ln addition, generally, on today's consumer market, it is an advantage if products, such aslawnmowers, comprise different features and functions while the products have conditionsand/or characteristics suitable for being manufactured and assembled in a cost-efficient mannef.

SUMMARYlt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a lawnmowercomprising a lawnmower chassis, lawnmower support members configured to abut against aground surface in a first plane during operation of the lawnmower, and a cutting unitconfigured to operate in a cutting plane. The cutting unit is pivotally arranged relative to thelawnmower chassis to pivot betvveen a first position and a second position. The anglebetween the cutting plane and the first plane is different when the cutting unit is in the second position than when the cutting unit is in the first position.

The angle between the cutting plane and a ground plane is a parameter of a lawnmoweraffecting the cutting result, the cutting efficiency, and the cutting resistance. A negative angleleads to poor cutting efficiency, poor cutting result, and a high cutting resistance. A negativeangle of the cutting unit relative to a ground surface can be defined as an angle in which atrailing edge of the cutting unit is closer to the ground surface than a leading edge of thecutting unit. A negative angle impairs the cutting efficiency because substantially the entirecutting unit is subjected to grass during movement of the lawnmower which slows down theoperation speed of the cutting unit. Moreover, most cutting units comprise cutting membersor cutting edges arranged at radial outer portions of the cutting unit. lf the angle between thecutting plane and a ground plane is negative, a radial centre portion of the cutting unit, which usually lacks cutting members or cutting edges, is also subjected to grass during movement 4 of the lawnmower which increases the cutting resistance, reduces the cutting efficiency and reduces the cutting result.

The best cutting result is obtained if the angle between the cutting plane and a ground planeis close to zero but still on the positive side. A positive angle of the cutting unit relative to aground surface can be defined as an angle in which the leading edge of the cutting unit is closer to the ground surface than the trailing edge of the cutting unit.

A positive angle helps keeping the operation speed of the cutting unit up and it will improvethe energy efficiency of the lawnmower. This because the cutting members or cutting edgesat the trailing edge of the cutting unit, and the radial centre portion of the cutting unit, will belocated at a greater distance from the ground surface than the leading edge of the cuttingunit and will thereby not be subjected to grass during movement of the lawnmower. However,if the angle is too big on the positive side, the cutting result may be affected to the negative.This because a large positive angle of the cutting unit relative to the ground surface maycreate a more curved cutting track. Curved cutting tracks may form visible cutting tracks in the lawn which impairs the cutting result.

The traditional way to solve the above mentioned issues is to arrange the cutting unit to havea built-in fixed positive angle of 2 - 5 degrees relative to the ground plane. Most often, agreater positive angle is selected than what is optimal in most operational conditionsregarding the cutting result and the cutting efficiency. This because it may be wanted to avoid a negative angle in as many situations as possible.

Since the cutting unit of the lawnmower according to the present disclosure is pivotallyarranged relative to the lawnmower chassis, a lawnmower is provided having conditions for amore advantageous angle betvveen the cutting plane and the ground plane at varying cuttingconditions. Accordingly, a lawnmower is provided having conditions for an improved cuttingresult, an improved cutting efficiency, and a reduced cutting resistance at different cuttingconditions. This because the cutting unit may be pivoted, manually or automatically, from thefirst position so as to obtain a more advantageous angle between the cutting plane and theground plane at varying cutting conditions. Moreover, a lawnmower is provided havingconditions for avoiding a negative angle between the cutting plane and the ground plane.This because the cutting unit may be pivoted, manually or automatically, so as to avoid anegative angle between the cutting plane and the ground plane during operation of the lawnmower.

Since the lawnmower has conditions for a more advantageous angle between the cuttingplane and the ground plane at varying cutting conditions, a lawnmower is provided havingconditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower. ln addition, since the cutting unit is pivotally arranged relative to the lawnmower chassis, amore durable lawnmower is provided. This because the cutting unit may pivot from the firstposition upon an impact between the cutting unit and an object, such as a stump, a stone, asticks, or the like. Moreover, the cutting unit may pivot from the first position upon roughhandling of the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

Accordingly, a lawnmower is provided overcoming, or at least alleviating, at least some of theabove-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the cutting plane is substantially parallel to the first plane when the cutting unit isin the first position. Thereby, a lawnmower is provided in which a great cutting result isobtained when the cutting unit is in the first position, while the cutting unit can be pivotedfrom the first position so as to obtain a more advantageous angle betvveen the cutting plane and the ground plane at varying cutting conditions.

Optionally, the angle between the cutting plane and a longitudinal direction of the lawnmoweris different when the cutting unit is in the second position than when the cutting unit is in thefirst position. Thereby, a lawnmower is provided having conditions for a more advantageousangle between the cutting plane and the longitudinal direction of the lawnmower at varyingcutting conditions. Thereby, a lawnmower is provided having conditions for an improvedcutting result, improved cutting efficiency, and reduced cutting resistance at different cuttingconditions. This because the cutting unit may be pivoted, manually or automatically, from thefirst position so as to obtain a more advantageous angle between the cutting plane and the longitudinal direction of the lawnmower at varying cutting conditions.

Optionally, the cutting unit is configured to pivot from the first position based on a loadexerted on the cutting unit by vegetation. As a result, the cutting unit can pivot from the firstposition to obtain a more advantageous angle relative to the ground plane based on the loadexerted on the cutting unit by vegetation. When the lawnmower according to the present solution reaches a portion of a lawn having higher length and/or density of the vegetation, the 6 load exerted on the cutting unit by vegetation will increase. Accordingly, a lawnmower isprovided having conditions for obtaining a more advantageous angle between the cuttingplane and the ground plane in an automatic manner based on the length and density of the vegetation.

As a further result thereof, a lawnmower is provided having conditions for an improvedenergy efficiency at varying cutting conditions, which potentially pro|ongs the available operational time of the lawnmower.

Optionally, the cutting unit is configured to pivot from the first position by a reaction forceobtained between the cutting unit and vegetation during operation of the lawnmower. As aresult, the cutting unit can pivot from the first position to obtain a more advantageous anglerelative to the ground plane by the reaction force obtained betvveen the cutting unit andvegetation. When the lawnmower according to the present solution reaches a portion of alawn having higher length and/or density of the vegetation, the reaction force obtainedbetween the cutting unit and vegetation will increase. Accordingly, a lawnmower is providedhaving conditions for obtaining a more advantageous angle between the cutting plane and the ground plane in an automatic manner based on the length and density of the vegetation.

Moreover, since the cutting unit is configured to pivot from the first position by the reactionforce obtained between the cutting unit and vegetation during operation of the lawnmower,the need for complex and costly arrangements is circumvented, such as sensors, motors,and the like, for adapting the angle of the cutting unit relative to the ground plane in anautomatic manner at varying cutting conditions. Accordingly, a lawnmower is provided havingconditions and characteristics suitable for being manufactured and assembled in a cost- efficient manner.

Optionally, the cutting unit is configured to pivot from the first position when a reaction forcebetween the cutting unit and vegetation exceeds a predetermined threshold value duringoperation of the lawnmower. Thereby, a lawnmower is provided in which the cutting unit maybe pivoted automatically from the first position when the reaction force between the cuttingunit and vegetation exceeds the predetermined threshold value during operation of the lawnmower so as to obtain a more advantageous angle between the cutting plane and the 7 ground plane. Accordingly, a lawnmower is provided having conditions for obtaining a moreadvantageous angle betvveen the cutting plane and the ground plane in an automatic mannerbased on the length and density of the vegetation. Moreover, it can be ensured that thecutting unit is not pivoted from the first position when the reaction force between the cuttingunit and the vegetation is below the predetermined threshold value during operation of thelawnmower. ln this manner, a more stable cutting unit is provided and unwanted movementsbetween the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit relative to the lawnmower chassis, can be avoided.

Furthermore, since a lawnmower is provided having conditions for obtaining a moreadvantageous angle between the cutting plane and the ground plane in an automatic mannerbased on the length and density of the vegetation, a lawnmower is provided havingconditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower.

Moreover, since the cutting unit is configured to pivot from the first position when a reactionforce between the cutting unit and vegetation exceeds a predetermined threshold valueduring operation of the lawnmower, the need for complex and costly arrangements iscircumvented, such as sensors, motors, and the like, for adapting the angle of the cutting unitrelative to the ground plane in an automatic manner at varying cutting conditions.Accordingly, a lawnmower is provided having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the lawnmower comprises a least one resilient element configured to bias thecutting unit towards the first position. Thereby, unwanted movements between the cuttingunit and the lawnmower chassis, such as wobbling of the cutting unit, can be avoided, and a more stable cutting unit is provided.

Optionally, the lawnmower comprises a least one damper configured to damp movementbetween the cutting unit and the lawnmower chassis. Thereby, unwanted movementsbetween the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit, can be avoided, and a more stable cutting unit is provided.

Optionally, the cutting unit is pivotally arranged relative to the lawnmower chassis around afirst pivot point, and wherein the first pivot point is arranged in front of a centre axis of thecutting unit seen in a fonNard direction of the lawnmower. Thereby, it can be ensured that the cutting unit can be pivoted from the first position to obtain a more advantageous angle 8 between the cutting plane and the ground plane during movement of the lawnmower in theforward direction of the lawnmower. That is, since the first pivot point is arranged in front ofthe centre axis of the cutting unit seen in the fonNard direction of the lawnmower, the cuttingunit is pivoted to obtain a more positive angle between the cutting plane and the groundplane when being pivoted from the first position. Accordingly, when the lawnmower istravelling in the fon/vard direction of the lawnmower and reaches a portion of a lawn havinggreater length and/or density of the vegetation, the reaction force between the cutting unitand the vegetation can apply can apply a torque onto the cutting unit which can displace the cutting unit from the first position towards a more positive angle relative to the ground plane.

When the angle of the cutting unit relative to the ground plane is positive, the leading edge ofthe cutting unit, seen in the fonNard direction of the lawnmower, is closer to the groundsurface than the trailing edge of the cutting unit, seen in the forward direction of thelawnmower. ln this manner, a lowered cutting resistance is obtained which lowers the energyconsumption of the lawnmower and potentially prolongs the available operational time of thelawnmower. ln addition, due to these features, a more constant cutting resistance can be obtained when mowing a lawn having varying length and/or density of the of the vegetation.

Moreover, due to these features, the risk of an obstruction of the cutting unit is reducedduring operation of the lawnmower. This because the cutting resistance can be loweredwhen the lawnmower reaches a portion of a lawn having greater length and/or density of thevegetation, and because the risk of build-up of vegetation onto an area surrounding the cutting unit can be reduced.

Optionally, the first pivot point is arranged at a distance from the centre axis within the rangeof 0.5 to 1.5 times a radius of the cutting unit, or within the range of 0.8 to 1.2 times theradius of the cutting unit. Thereby, it can be ensured that an advantageous distance betweenthe ground surface and the leading edge of the cutting unit, seen in the fonNard direction of the lawnmower, is maintained when the cutting unit is pivoted from the first position.

Optionally, the vertical distance between the first pivot point and cutting members of thecutting unit is within the range of 15% - 60%, or 25% - 45% of a radius of the cutting unit.Thereby, it can be ensured that the cutting unit can be pivoted from the first position in areliable and efficient manner to obtain a more advantageous angle between the cutting plane and the ground plane. 9 Optionally, the cutting unit is pivotally arranged relative to the lawnmower chassis around asecond pivot point, and wherein the second pivot point is arranged behind a centre axis ofthe cutting unit seen in a forward direction of the lawnmower. Thereby, it can be ensured thatthe cutting unit can be pivoted from the first position to obtain a more advantageous anglebetween the cutting p|ane and the ground p|ane during movement of the lawnmower in areverse direction of the lawnmower. That is, since the second pivot point is arranged behindthe centre axis of the cutting unit seen in the forward direction of the lawnmower, the cuttingunit is pivoted to obtain a more positive angle between the cutting p|ane and the groundp|ane when the lawnmower is trave||ing in the reverse direction and the cutting unit is pivotedaround the second pivot point. That is, when the lawnmower is trave||ing in the reversedirection of the lawnmower and reaches a portion of a |awn having greater length and/ordensity of the vegetation, the reaction force between the cutting unit and the vegetation canapply can apply a torque onto the cutting unit which can displace the cutting unit towards a more positive angle relative to the ground p|ane seen in the reverse direction.

When the angle of the cutting unit relative to the ground p|ane is positive, the leading edge ofthe cutting unit, seen in the reverse direction of the lawnmower, is closer to the cutting unitthan the trailing edge of the cutting unit, seen in the reverse direction of the lawnmower. lnthis manner, a lowered cutting resistance can be obtained when the lawnmower moves in thereverse direction which lowers the energy consumption of the lawnmower and potentiallyprolongs the available operational time of the lawnmower. ln addition, due to these features,a more constant cutting resistance can be obtained when mowing a |awn having varying length and/or density of the of the vegetation.

Moreover, due to these features, the risk of an obstruction of the cutting unit is reducedduring operation of the lawnmower. This because the cutting resistance can be lowered alsowhen the lawnmower is trave||ing in the reverse direction and reaches a portion of a |awnhaving greater length and/or density of the vegetation, and because the risk of build-up of vegetation onto an area surrounding the cutting unit can be reduced.

Furthermore, since the cutting unit may be pivotally arranged relative to the lawnmowerchassis around two pivot points, an even more durable lawnmower can be provided. Thisbecause the cutting unit may pivot also around the second pivot point upon an impactbetween the cutting unit and an object, such as a stump, a stone, a sticks, or the like.Moreover, the cutting unit may pivot also around the second pivot point upon rough handlingof the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

A prior-art lawnmower having a built-in fixed positive angle of 2 - 5 degrees relative to theground plane seen in the forward direction obtains a negative angle of the same magnitude,i.e. of 2 - 5 degrees, between the cutting plane and the ground plane, seen in the reversedirection, when the lawnmower moves in the reverse direction. As a result thereof, suchlawnmowers obtain a reduced cutting result, a reduced cutting efficiency, and an increasedcutting resistance when moving in a reverse direction. However, since the second pivot pointaccording to these embodiments of the lawnmower is arranged behind the centre axis of thecutting unit seen in the fonNard direction of the lawnmower, a negative angle between thecutting plane and the ground plane, seen in the reverse direction, can be avoided duringreverse travel of the lawnmower. Moreover, due to these features, a lawnmower can beprovided having the same advantageous positive angle between the cutting plane and theground plane during movement in the reverse direction as when moving in the fonNarddirection, which opens up the possibility of new designs of lawnmowers capable of operating equally good in both travel directions.

Optionally, the second pivot point is arranged at a distance from the centre axis within therange of 0.5 to 1.5 times a radius of the cutting unit, or within the range of 0.8 to 1.2 times theradius of the cutting unit. Thereby, it can be ensured that an advantageous distance betweenthe ground surface and the leading edge of the cutting unit, seen in the reverse direction of the lawnmower, is maintained when the cutting unit is pivoted from the first position.

Optionally, the lawnmower comprises a holding member, wherein the cutting unit is pivotallyarranged relative to the lawnmower chassis via the holding member, and wherein the holdingmember is configured to abut against a first seat when the cutting unit is in the first position,and is configured to be lifted from the first seat when the cutting unit is pivoted from the firstposition. Thereby, unwanted movements between the cutting unit and the lawnmowerchassis, such as wobbling of the cutting unit, can be prevented, and a more stable cuttingunit can be provided. ln addition, pivoting movement of the cutting unit from the first positionin a direction away from the second position can be prevented. Moreover, a simple, efficient,and low-cost arrangement can be provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the holding member is configured to abut against a second seat when the cuttingunit is in the first position. Thereby, unwanted movements between the cutting unit and thelawnmower chassis, such as wobbling of the cutting unit, can be prevented, and a more stable cutting unit can be provided. ln addition, a distinct and precise first position of the 11 cutting unit can be provided. Moreover, a simple, efficient, and low-cost arrangement can be provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the abutting contact bet\Neen the holding member and the second seat forms thefirst pivot point. Thereby, a simple, efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the abutting contact between the holding member and the first seat forms thesecond pivot point. Thereby, a simple, efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the cutting unit is configured to be lifted from the second seat when the cuttingunit is pivoted around the second pivot point from the first position. Thereby, a simple,efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally around two pivot points relative to the lawnmower chassis.

Optionally, the lawnmower comprises a driving unit configured to drive the cutting unit duringoperation of the lawnmower, and wherein the driving unit is arranged to pivot with the cuttingunit. Thereby, the need for one or more components or arrangements capable of transferringpower at different inclination angels, such as one or more universal joints, between thedriving unit and the cutting unit is circumvented. Accordingly, a lawnmower is providedhaving conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the cutting unit comprises a cutting disc provided with a number of cuttingmembers arranged at a periphery of the cutting disc. Thereby, an energy efficient cutting unitis provided capable of obtaining a more advantageous angle between the cutting plane and the ground plane during operation of the lawnmower.

Optionally, the cutting members are pivotally arranged to the cutting disc. Thereby, an energyefficient cutting unit is provided capable of obtaining a more advantageous angle betweenthe cutting plane and the ground plane during operation of the lawnmower. Moreover, alawnmower is provided with reduced risk of injury, and damage to the lawnmower, in case of an impact between a cutting member and an object.

Optionally, the lawnmower is a self-propelled autonomous robotic lawnmower. Thereby, robotic lawnmower is provided having conditions for a more advantageous angle between 12 the cutting plane and the ground plane at varying cutting conditions. Accordingly, a roboticlawnmower is provided having conditions for an improved cutting result, improved cuttingefficiency, and reduced cutting resistance at different cutting conditions. This because thecutting unit may be pivoted, manually or automatically, from the first position so as to obtain amore advantageous angle between the cutting plane and the ground plane at varying cuttingconditions. Moreover, a robotic lawnmower is provided having conditions for avoiding anegative angle between the cutting plane and the ground plane. This because the cutting unitmay be pivoted, manually or automatically, so as to avoid a negative angle between the cutting plane and the ground plane during operation of the robotic lawnmower.

Since the robotic lawnmower has conditions for a more advantageous angle between thecutting plane and the ground plane at varying cutting conditions, a robotic lawnmower isprovided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the robotic lawnmower. ln addition, since the cutting unit is pivotally arranged relative to the robotic lawnmowerchassis, a more durable robotic lawnmower is provided. This because the cutting unit maypivot from the first position upon an impact between the cutting unit and an object, such as astump, a stone, a sticks, or the like. Moreover, the cutting unit may pivot from the firstposition upon rough handling of the robotic lawnmower, such as when a user carries therobotic lawnmower and drops the robotic lawnmower such that the cutting unit is hitting an object.

Accordingly, a self-propelled robotic lawnmower is provided overcoming, or at leastalleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the lawnmower comprises an actuator assembly configured to pivot the cuttingunit relative to the lawnmower chassis so as to change the angle between the cutting planeand the first plane. Thereby, a lawnmower is provided in which the angle between the cuttingplane and the first plane can be adjusted using the actuator assembly. For example, theangle between the cutting plane and the first plane can be adjusted based on cuttingconditions and/or cutting requirements. That is, conditions are provided for a user, or acontrol arrangement, to select the angle between the cutting plane and the first plane basedon cutting conditions, such as a length and/or density of vegetation of an area to be cut,and/or to select the angle between the cutting plane and the first plane based on cutting requirements, such cutting speed, cutting result, and/or energy consumption. As an example, 13 if cutting speed and energy consumption are prioritized requirements, the angle between thecutting plane and the first plane can be adjusted to a greater positive angle, using theactuator assembly. As another example, if cutting result is the most prioritized requirement,the angle betvveen the cutting plane and the first plane can be adjusted to a smaller positive angle, using the actuator assembly.

Moreover, since the lawnmower comprises the actuator assembly, the actuator assembly canbe used to pivot the cutting assembly to obtain a more advantageous angle between thecutting plane and the first plane in the travelling direction of the lawnmower also when thelawnmower is travelling in a reverse direction of the lawnmower, for example by reducing theangle between the cutting plane and the first plane or by obtaining a positive angle in the travel direction when reversing the lawnmower.

Furthermore, since the lawnmower comprises the actuator assembly, the actuator assemblycan be used to eliminate manufacturing tolerances affecting the angle between the cutting plane and the first plane, for example in an assembling process of the lawnmower.

Optionally, the lawnmower comprises an input unit and a control arrangement, and whereinthe control arrangement is configured to control the actuator assembly to pivot the cuttingunit to a set angle relative to the lawnmower chassis based on data from the input unit.Thereby, a lawnmower is provided capable of adapting the angle between the cutting planeand the first plane in an automatic manner based on data from the input unit. ln this manner,a more advantageous angle between the cutting plane and the ground plane can be obtained in an automatic manner at varying cutting conditions.

According to some embodiments, the input unit allows input from a user. That is, accordingto some embodiments, the input unit allows a user to select a wanted angle between thecutting plane and the first plane, or allows a user to select between different modes orprograms representing different priorities between requirements such as cutting speed,energy consumption, and cutting result. ln this manner, a more user friendly lawnmower isprovided having conditions for an improved cutting result, an improved cutting efficiency, and a reduced cutting resistance at different cutting conditions.

Optionally, the input unit is configured to obtain data representative of a current position ofthe lawnmower, and wherein the control arrangement is configured to determine the setangle based on the current position of the lawnmower. Thereby, a lawnmower is provided capable of adapting the angle between the cutting plane and the first plane based on the 14 position of the lawnmower. ln this manner, conditions are provided for cutting some areas ofa lawn faster using less energy and cutting some other areas of the lawn with a highercutting result. ln this manner, a lawn can be divided into different areas having differentdemands on lawn appearance and cutting result. As an example, a user may select an areaof a lawn close to a house as a first area and an area of a lawn remote from the house as asecond area. The second area may for example be an area of the lawn normally hidden byshrubs, trees, garden furniture, or the like. The control arrangement may then control theactuator assembly to obtain a small positive angle when the lawnmower is in the first areaand may control the actuator assembly to obtain a greater positive angle when thelawnmower is in the second area. ln this manner, the first area is cut with higher precision,i.e. with a higher cutting result, than the second area, and the second area is cut with a lowercutting resistance than the first area, i.e. with a reduced energy consumption. ln addition, due to the greater positive angle, the second area can be cut faster.

Optionally, the input unit is configured to obtain data representative of a current cuttingresistance, and wherein the control arrangement is configured to determine the set anglebased on the current cutting resistance. Thereby, a lawnmower is provided capable ofadapting the angle between the cutting plane and the first plane in an automatic mannerbased on the cutting resistance. As understood from the herein described, the cuttingresistance increases with increased length and density of the vegetation being cut.Moreover, the cutting resistance increases with increased travel speed of the lawnmower.According to some embodiments, the control arrangement may be configured to increase theangle between the cutting plane and the first plane with increased cutting resistance and maybe configured to decrease the angle between the cutting plane and the first plane withdecreased cutting resistance. ln this manner, the angle between the cutting plane and thefirst plane can be adjusted in an automatic manner based on the length and density of thevegetation being cut and based on the travel speed of the lawnmower. ln this manner, agood compromise can be provided between lawn appearance and cutting efficiency at all times and at varying cutting conditions.

Optionally, the lawnmower comprises an electric motor configured to drive the cutting unitduring operation of the lawnmower, and wherein the input unit is configured to obtain datarepresentative of the current cutting resistance by monitoring electrical quantities of theelectric motor. Thereby, the cutting resistance is obtained in a simple, reliable, and cost- efficient manner.

Optionally, the actuator assembly is an electrical actuator assembly. Thereby, a simple andefficient actuator assembly is provided having conditions for an automatic adaptation of the angle between the cutting plane and the first plane.

According to a second aspect of the invention, the object is achieved by a lawnmowercomprising a lawnmower chassis, lawnmower support members configured to abut against aground surface in a first plane during operation of the lawnmower, and a cutting unit. Thecutting unit is movably arranged relative to the lawnmower chassis to move between a firstposition and a second position. The distance between at least a portion of the cutting unitand the first plane is different when the cutting unit is in the second position than when thecutting unit is in the first position. The cutting unit is configured to move from the first positionto the second position by a reaction force obtained between the cutting unit and vegetation during operation of the lawnmower.

Since the cutting unit is configured to move from the first position to the second position by areaction force obtained between the cutting unit and vegetation during operation of thelawnmower, a lawnmower is provided capable of obtaining a more advantageous distancebetween at least a portion of the cutting unit and the ground plane by the reaction force obtained between the cutting unit and vegetation during operation of the lawnmower. ln this manner, a lawnmower is provided having conditions for an improved cutting result, animproved cutting efficiency, and a reduced cutting resistance at different cutting conditions.That is, when the lawnmower according to the present solution reaches a portion of a lawnhaving higher length and/or density of the vegetation, the reaction force obtained betweenthe cutting unit and vegetation will increase. Since the cutting unit is configured to move fromthe first position to the second position by the reaction force obtained between the cuttingunit and vegetation during operation of the lawnmower, a lawnmower is provided capable ofobtaining a more advantageous distance between at least a portion of the cutting unit andthe ground plane in an automatic manner based on the current length and/or density of the vegetation.

As a further result thereof, a lawnmower is provided having conditions for an improvedenergy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower.

Moreover, since the cutting unit is configured to move from the first position by the reaction force obtained between the cutting unit and vegetation during operation of the lawnmower, 16 the need for complex and costly arrangements is circumvented, such as sensors, motors,and the like, for moving the cutting unit relative to the ground plane in an automatic mannerat varying cutting conditions. Accordingly, a lawnmower is provided having conditions and Characteristics suitable for being manufactured and assembled in a cost-efficient manner. ln addition, since the cutting unit is movably arranged relative to the lawnmower chassis, amore durable lawnmower is provided. This because the cutting unit may move from the firstposition upon an impact between the cutting unit and an object, such as a stump, a stone, asticks, or the like. Moreover, the cutting unit may move from the first position upon roughhandling of the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

The lawnmower according to the second aspect of the invention is combinable with any oneof the features of the lawnmower according to the first aspect of the invention explainedherein. That is, the lawnmower according to the second aspect of the invention maycomprise one or more of the features of the lawnmower according to the first aspect of theinvention explained herein. ln other words, the lawnmower according to the second aspect ofthe invention may comprise the same features, functions, and advantages as the lawnmower according to the first aspect of the invention explained herein.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGSVarious aspects of the invention, including its particularfeatures and advantages, will bereadily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates a lawnmower according to some embodiments of the presentdisclosure, Fig. 2 schematically illustrates a chassis member of the lawnmower illustrated in Fig. 1, Fig. 3 illustrates the chassis member illustrated in Fig. 2 with a cutting unit in a second position, 17 Fig. 4 illustrates the chassis member illustrated in Fig. 2 and Fig. 3 with the cutting unit in athird position, Fig. 5 schematically illustrates a chassis member, according to some further embodiments, ofa lawnmower, and Fig. 6 illustrates a lawnmower, according to some embodiments, illustrated as mowing a lawn.

DETAILED DESCRIPTIONAspects of the present invention will now be described more fully. Like numbers refer to likeelements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates a lawnmower 1 according to some embodiments of thepresent disclosure. According to the illustrated embodiments, the lawnmower 1 is a self-propelled autonomous robotic lawnmower 1 capable of navigating and cutting grass in anautonomous manner in an area without the intervention or the control of a user. For thereason of brevity and clarity, the self-propelled autonomous robotic lawnmower 1 is in someplaces herein referred to as “the robotic lawnmower 1” or simply the “lawnmower 1”.According to the illustrated embodiments, the robotic lawnmower 1 is configured to be usedto cut grass in areas used for aesthetic and recreational purposes, such as gardens, parks,city parks, sports fields, lawns around houses, apartments, commercial buildings, offices,and the like.

The lawnmower 1 comprises a lawnmower chassis 3 and a number of lawnmower supportmembers 5, 5' each configured to abut against a ground surface 7 in a first plane P1 duringoperation of the lawnmower 1. Accordingly, the first plane P1 will extend along a groundsurface 7 when the lawnmower 1 is positioned on a flat ground surface 7. According to theillustrated embodiments, the lawnmower support members 5, 5' is wheels 5, 5' of thelawnmower 1. According to the illustrated embodiments, the lawnmower 1 comprises fourwheels 5, 5', namely two drive wheels 5 and t\No support wheels 5”. The drive wheels 5 of thelawnmower 1 may each be powered by an electrical motor of the lawnmower 1 to providemotive power and/or steering of the lawnmower 1. ln Fig. 1, a longitudinal direction ld of thelawnmower 1 is indicated. The longitudinal direction ld of the lawnmower 1 extends in alongitudinal plane LP of the lawnmower 1. The longitudinal plane LP is parallel to the firstplane P1. The longitudinal direction ld of the lawnmower1 is thus parallel to the first plane P1and thus also to a ground surface 7 when the lawnmower 1 is positioned onto a flat ground surface 7. Moreover, the longitudinal direction ld of the lawnmower 1 is parallel to a fonNard 18 direction fd of travel of the lawnmower 1 as well as a reverse direction rd of travel of the lawnmower 1, as is further explained herein.

According to the illustrated embodiments, the drive wheels 5 of the lawnmower 1 are non-steered wheels having a fix rolling direction in relation to the lawnmower chassis 3. Therespective rolling direction of the drive wheels 5 of the lawnmower 1 is substantially parallelto the longitudinal direction ld of the lawnmower 1. According to the illustrated embodiments,the support wheels 5' are non-driven wheels. Moreover, according to the illustratedembodiments, the support wheels 5' can pivot around a respective pivot axis such that therolling direction of the respective support wheel 5' can follow a travel direction of the lawnmower 1.

As understood from the above, when the drive wheels 5, 5' of the lawnmower 1 are rotated atthe same rotational velocity in a fonNard rotational direction, and no wheel slip is occurring,the lawnmower1 will move in the fonNard direction fd indicated in Fig. 1. Likewise, when thedrive wheels 5, 5' of the lawnmower 1 are rotated at the same rotational velocity in a reverserotational direction, and no wheel slip is occurring, the lawnmower 1 will move in the reverse direction rd indicated in Fig. 1. The reverse direction rd is opposite to the forward direction fd.

According to the illustrated embodiments, the lawnmower 1 may be referred to as a four-wheeled rear wheel driven lawnmower 1. According to further embodiments, the lawnmower1 may be provided with another number of wheels 5, 5', such as three wheels. Moreover,according to further embodiments, the lawnmower 1 may be provided with anotherconfiguration of driven and non-driven wheels, such as a front wheel drive or an all-wheel drive.

According to the illustrated embodiments, the lawnmower 1 comprises a control arrangement2. The control arrangement 2 may be configured to control propulsion of the lawnmower 1,and steer the lawnmower 1, by controlling electrical motors of the lawnmower 1 arranged todrive the drive wheels 5 of the lawnmower 1. According to further embodiments, the controlarrangement 2 may be configured to steer the lawnmower 1 by controlling the angle ofsteered wheels of the lawnmower 1. According to still further embodiments, the robotic toolmay be an articulated robotic tool, wherein the control arrangement 2 may be configured tosteer the robotic tool by controlling the angle between frame portions of the articulated robotic tool. 19 The control arrangement 2 may be configured to control propulsion of the lawnmower 1, andsteer the lawnmower 1, so as to navigate the lawnmower 1 in an area to be operated. Thelawnmower 1 may further comprise one or more sensors arranged to sense a magnetic fieldof a wire, and/or one or more positioning units, and/or one or more sensors arranged todetect an impending or ongoing collision event with an object. ln addition, the lawnmower 1may comprise a communication unit connected to the control arrangement 2. Thecommunication unit may be configured to communicate with a remote communication unit toreceive instructions therefrom and/or to send information thereto. The communication maybe performed wirelessly over a wireless connection such as the internet, or a wireless localarea network (WLAN), or a wireless connection for exchanging data over short distancesusing short-wavelength, i.e. ultra-high frequency (UHF) radio waves in the industrial,scientific, and medical (ISM) band from 2.4 to 2.485 GHz.

The control arrangement 2 may be configured to control propulsion of the lawnmower 1, andsteer the lawnmower 1, so as to navigate the lawnmower 1 in a systematic and/or randompattern to ensure that an area is completely covered, using input from one or more of theabove described sensors and/or units. Furthermore, the lawnmower 1 may comprise one ormore batteries arranged to supply electricity to components of the lawnmower 1. As anexample, the one or more batteries may be arranged to supply electricity to electrical motors of the lawnmower 1 by an amount controlled by the control arrangement 2.

The lawnmower 1 comprises a cutting unit 9. The cutting unit 9 is configured to operate in acutting plane PC. According to the illustrated embodiments, the cutting unit 9 is configured torotate in the cutting plane PC around a rotation axis ra. The rotation axis ra is perpendicular to the cutting plane PC.

The cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 to pivot betweena first position and a second position. ln Fig. 1, the cutting unit 9 is illustrated in the firstposition. As is further explained herein, the angle between the cutting plane PC and the firstplane P1 is different when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position.

Fig. 2 schematically illustrates a chassis member 3' of the lawnmower 1 illustrated in Fig. 1.As can be seen in Fig. 2, the chassis member 3' comprises the cutting unit 9 and a drivingunit 17 configured to rotate the cutting unit 9 around the rotation axis ra of the cutting unit 9during operation of the lawnmower 1. The driving unit 17 may comprise an electric motor 17.

As indicated in Fig. 2, according to the illustrated embodiments, the rotation axis ra of the cutting unit 9 corresponds to a centre axis ca of the cutting unit 9. The chassis member 3' isstationary arranged relative to the lawnmower chassis 3 indicated in Fig. 1 during operationof the lawnmower 1. However, according to some embodiments, the lawnmower 1 maycomprise an adjustment mechanism via which a user can adjust the mounting position of thechassis member 3' relative to the lawnmower chassis 3 indicated in Fig. 1 so as to adjust the distance between the cutting plane PC of the cutting unit 9 and the first plane P1.

According to the i||ustrated embodiments, the cutting unit 9 comprises a cutting disc 20provided with a number of cutting members 22 arranged at a periphery 20' of the cutting disc20. Moreover, according to the i||ustrated embodiments, the cutting members 22 are pivotallyarranged to the cutting disc 20. The cutting members 22 comprise sharp cutting edges configured to cut vegetation, such as grass, during rotation of the cutting unit 9. ln Fig. 2, the cutting unit 9 is i||ustrated in the first position. As can be seen in Fig. 2, as wellas in Fig. 1, according to the i||ustrated embodiments, the cutting plane PC is substantiallyparallel to the first plane P1 when the cutting unit 9 is in the first position. However, accordingto further embodiments, the first position, as referred to herein, may constitute a position inwhich the cutting plane PC is angled relative to the first plane P1, for example by an angle within the range of zero to five degrees.

Fig. 3 i||ustrates the chassis member 3' i||ustrated in Fig. 2 with the cutting unit 9 in a secondposition. The “second position” as referred to herein may not be a particular distinct positionof the cutting unit 9, such as an end position of the cutting unit 9. lnstead, the “secondposition” as referred to herein may be any other position of the cutting unit 9 different from the first position of the cutting unit 9, as referred to herein.

As is evident when comparing Fig. 3 and Fig. 2, the angle between the cutting plane PC anda longitudinal direction ld of the lawnmower1 is different when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position.

According to the i||ustrated embodiments, the cutting unit 9 is configured to pivot from thefirst position based on a load exerted on the cutting unit 9 by vegetation. The load exerted onthe cutting unit 9 by vegetation depends on a current length and/or density of the vegetationbeing cut by the cutting unit 9, as well as on a travel speed of the lawnmower 1. ln Fig. 3, thechassis member 3' is i||ustrated in a situation in which the lawnmower 1 is travelling in the forward direction fd indicated in Fig. 1 - Fig. 3. The cutting unit 9 is configured to pivot from 21 the first position to the second position by a reaction force obtained betvveen the cutting unit 9 and vegetation during operation of the lawnmower 1.

According to the illustrated embodiments, the cutting unit 9 is pivotally arranged relative tothe lawnmower chassis 3 around a first pivot point pp1, wherein the first pivot point pp1 isarranged in front of a centre axis ca of the cutting unit 9 seen in a forward direction fd of thelawnmower 1. Moreover, the first pivot point pp1 is arranged such that the cutting p|ane PC islocated between the first pivot point pp1 and the first p|ane P1. Furthermore, according to theillustrated embodiments, the first pivot point pp1 is arranged at a distance d1 from the centreaxis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9.The distance d1 is measured in a p|ane parallel to the cutting p|ane PC. The radius r of thecutting unit 9 is measured in the cutting p|ane PC from the centre axis ca of the cutting unit 9to a radia| outer periphery 9' of the cutting unit 9. According to the illustrated embodiments,the radia| outer periphery 9' of the cutting unit 9 corresponds to a radia| outer periphery of thecutting members 22. According to further embodiments, the first pivot point pp1 may bearranged at a distance d1 from the centre axis ca within the range of 0.5 to 1.5 times theradius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cuttingunit 9. According to the illustrated embodiments, the cutting unit 9 is configured to pivotaround the first pivot point pp1 based on the load exerted on the cutting unit 9 by vegetation when the lawnmower 1 is trave||ing in the forward direction fd.

Due to these features, the cutting unit 9 will be moved from the first position to the secondposition by a reaction force obtained between the cutting unit 9 and vegetation duringoperation of the lawnmower 1 when the lawnmower 1 is trave||ing in the forward direction fd.According to the illustrated embodiments, the movement of the cutting unit 9 will constitute apivoting movement of the cutting unit 9 around the first pivot point pp1. Accordingly, due tothese features, a lawnmower 1 is provided capable of adapting the angle of the cutting unit 9in relation to the first p|ane based on a current length and/or density of the vegetation being cut.

As can be seen when comparing Fig. 2 and Fig. 3, a distance D1 between a leading edge ofthe cutting unit 9 and the first p|ane P1 is substantially the same when the cutting unit 9 is inthe second position as compared to when the cutting unit 9 is in the first position. This is dueto the fact that, according to the illustrated embodiments, the first pivot point pp1 is arrangedat a distance d1 from the centre axis ca of the cutting unit 9 substantially corresponding tothe radius r of the cutting unit 9. Since the distance D1 between the leading edge of the cutting unit 9 and the first p|ane P1 is substantially the same when the cutting unit 9 is in the 22 second position as compared to when the cutting unit 9 is in the first position, the cuttingheight of the lawnmower 1 can be maintained also when the cutting unit 9 is in the second position.

Moreover, as can be seen when comparing Fig. 2 and Fig. 3, the distance D2 between thetrailing edge 9' of the cutting unit 9 and the first p|ane P1 is greater when the cutting unit 9 isin the second position than when the cutting unit 9 is in the first position. Likewise, thedistance betvveen other portions of the cutting unit 9 and the first p|ane P1, such as a centreportion of the cutting unit 9, is greater when the cutting unit 9 is in the second position thanwhen the cutting unit 9 is in the first position. Thereby, a lowered cutting resistance isobtained when the cutting unit 9 is in the second position. Accordingly, due to these features,a lawnmower 1 is provided capable of adapting the cutting resistance based on a current length and/or density of the vegetation being cut.

According to the i||ustrated embodiments, the lawnmower 1 comprises a holding member 15.The cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 via the holdingmember 15. As can be seen in Fig. 1, the holding member 15 is configured to abut against afirst seat s1 when the cutting unit 9 is in the first position. Moreover, as can be seen in Fig. 2,the holding member 15 is configured to be lifted from the first seat s1 when the cutting unit 9is pivoted from the first position. Furthermore, as can be seen in Fig. 2, the driving unit 17 is arranged to pivot with the cutting unit 9.

According to the i||ustrated embodiments, the lawnmower 1 comprises two resilient elements11, 12 each configured to bias the cutting unit 9 towards the first position. According tofurther embodiments, the lawnmower 1 may comprise a least one resilient element 11, 12configured to bias the cutting unit 9 towards the first position. According to the i||ustratedembodiments, the resilient elements 11, 12 applies a biasing force onto the holding membersuch that the holding member 15 is pressed towards the first seat s1. According to thei||ustrated embodiments, the resilient elements 11, 12 each comprises a coil spring.According to further embodiments, the resilient elements 11, 12 may each comprise another type of resilient element, such as a rubber element, a leaf spring, or the like.

Due to these features, according to the i||ustrated embodiments, the cutting unit 9 isconfigured to pivot from the first position when a reaction force between the cutting unit 9 andvegetation exceeds a predetermined threshold value during operation of the lawnmower 1.That is, if the reaction force between the cutting unit 9 and vegetation is below a predetermined threshold value, the holding member 15 will remain in abutting contact with 23 the first seat 15. The predetermined threshold value is determined by spring coefficients ofthe resilient elements 11, 12, the location of the first pivot point pp1 in relation to the cuttingplane PC, the location of the first pivot point pp1 in relation to the leading edge of the cuttingunit 9, the weight of the pivoting parts of the chassis member 3', and gyroscopic effects ofrotating parts of the chassis member 3”. The predetermined threshold value may bedetermined to a value ensuring that the cutting unit 9 is pivoted from the first position when itprovides positive effects on the cutting resistance, the cutting result, and/or the cutting efficiency of the lawnmower 1.

According to the illustrated embodiments, the lawnmower1 comprises a damper 13. Due tothe damper 13, a more stable cutting unit 9 is provided and unwanted movements betvveenthe cutting unit 9 and the lawnmower chassis 3', such as wobbling of the cutting unit 9relative to the lawnmower chassis 3', can be avoided. The damper 13 is configured to dampmovement between the cutting unit 9 and the lawnmower chassis 3 by damping movementbetween the holding member 15 and the chassis member 3”. ln Fig. 2 and Fig. 3, only onedamper 13 is illustrated. However, the lawnmower 1 may comprise more than one damper13, for example including one damper arranged at the resilient element 12 provided with the reference sign “12” in Fig. 2 and Fig. 3.

As can be seen in Fig. 2, the holding member 15 is configured to abut against a second seats2 when the cutting unit 9 is in the first position. Moreover, as seen in Fig. 3, the abutting contact between the holding member 15 and the second seat s2 forms the first pivot point pp1.

According to the illustrated embodiments, the vertical distance vd1, indicated in Fig. 2,between the first pivot point pp1 and the cutting members 22 of the cutting unit 20 isapproximately 25% of the radius r of the cutting unit 9. According to further embodiments, thevertical distance vd1 between the first pivot point pp1 and cutting members 22 of the cuttingunit 20 may be within the range of 15% - 90%, or 25% - 45% of the radius r of the cutting unit9. ln this manner, it can be ensured that the cutting unit 9 can be pivoted from the first position in a reliable and efficient manner.

As is further explained herein, according to the illustrated embodiments, the cutting unit 9 ispivotally arranged relative to the lawnmower chassis 3 around a second pivot point pp2. Thesecond pivot point pp2 is arranged behind the centre axis ca of the cutting unit 9 seen in the forward direction fd of the lawnmower 1. 24 Fig. 4 illustrates the chassis member 3' illustrated in Fig. 2 and Fig. 3 with the cutting unit 9 ina third position. The “third position” as referred to herein may not be a particular distinctposition of the cutting unit 9, such as an end position of the cutting unit 9. lnstead, the “thirdposition” as referred to herein may be any other position of the cutting unit 9 different from the first position of the cutting unit 9, as referred to herein.

As is evident when comparing Fig. 4 and Fig. 2, the angle between the cutting plane PC anda longitudinal direction ld of the lawnmower1 is different when the cutting unit 9 is in the third position than when the cutting unit 9 is in the first position. ln Fig. 4, the chassis member 3' is illustrated in a situation in which the lawnmower1 istravelling in the reverse direction rd indicated in Fig. 1 - Fig. 4. The cutting unit 9 isconfigured to pivot around the second pivot point pp2 from the first position towards the thirdposition by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower 1 in the reverse direction rd.

Moreover, the second pivot point pp2 is arranged such that the cutting plane PC is locatedbetween the second pivot point pp2 and the first plane P1. Furthermore, according to theillustrated embodiments, the second pivot point pp2 is arranged at a distance d2 from thecentre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cuttingunit 9. The distance d2 is measured in a plane parallel to the cutting plane PC. According tofurther embodiments, the second pivot point pp2 may be arranged at a distance d2 from thecentre axis ca within the range of 0.5 to 1.5 times the radius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cutting unit 9.

Due to these features, the cutting unit 9 will be moved from the first position towards the thirdposition by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower 1 when the lawnmower 1 is travelling in the reverse direction rd.According to the illustrated embodiments, the movement of the cutting unit 9 will constitute a pivoting movement of the cutting unit 9 around the second pivot point pp2.

As can be seen when comparing Fig. 2 and Fig. 4, a distance D2 between a leading edge 9'of the cutting unit 9 and the first plane P1 is substantially the same when the cutting unit 9 isin the third position as compared to when the cutting unit 9 is in the first position. This is dueto the fact that, according to the illustrated embodiments, the second pivot point pp2 isarranged at a distance d2 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9. Since the distance D2 between the leading edge 9' of the cutting unit 9 and the first plane P1 is substantially the same when the cuttingunit 9 is in the second position as compared to when the cutting unit 9 is in the first position,the cutting height of the lawnmower 1 can be maintained also when the cutting unit 9 is in the third position.

As can be seen in Fig. 4, the abutting contact between the holding member 15 and the firstseat s1 forms the second pivot point pp2. Moreover, as can be seen in Fig. 4, the cutting unit9 is configured to be lifted from the second seat s2 when the cutting unit 9 is pivoted around the second pivot point pp2 from the first position.

The cutting unit 9 may be configured to pivot from the first position towards the third positionwhen a reaction force bet\Neen the cutting unit 9 and vegetation exceeds a predeterminedthreshold value during operation of the lawnmower in the reverse direction rd. Thepredetermined threshold value may have the same magnitude as the predetermined threshold value explained with reference to Fig. 3.

The following will be explained with simultaneous reference to Fig. 1 - Fig. 4. As is explainedherein, the angle between the cutting plane PC and the first plane P1 is a parameter of alawnmower 1 affecting the cutting result, the cutting efficiency, and the cutting resistance. Anegative angle leads to poor cutting efficiency, poor cutting result, and a high cuttingresistance. A negative angle of the cutting unit 9 relative to the first plane P1 can be definedas an angle in which a trailing edge of the cutting unit 9 is closer to the first plane P1 than aleading edge of the cutting unit 9 seen in the moving direction fd, rd of the lawnmower 1. Anegative angle impairs the cutting efficiency because substantially the entire cutting unit 9 issubjected to grass during movement of the lawnmower 1 which slows down the operationspeed of the cutting unit 9. lfthe angle between the cutting plane PC and a first plane P1 isnegative, a radial centre portion of the cutting unit 9, which usually lacks cutting members 22,is also subjected to grass during movement of the lawnmower 1 which increases the cutting resistance, reduces the cutting efficiency and reduces the cutting result.

A positive angle of the cutting unit 9 relative to a first plane P1 can be defined as an angle inwhich the leading edge of the cutting unit 9 is closer to the first plane P1 than the trailingedge of the cutting unit 9 seen in the moving direction fd, rd of the lawnmower 1. A positiveangle helps keeping the operation speed of the cutting unit 9 up and it will improve theenergy efficiency of the lawnmower 1. This because the cutting members 22 or cutting edgesat the trailing edge of the cutting unit 9, and the radial centre portion of the cutting unit 9, will be located at a greater distance from the first plane P1 than the leading edge of the cutting 26 unit 9 and will thereby not be subjected to grass during movement of the lawnmower 1.However, if the angle is too big on the positive side, the cutting result may be affected to thenegative. This because a large positive angle of the cutting unit 9 relative to the first plane P1may create a more curved cutting track. Curved cutting tracks may form visible cutting tracks in the lawn which impairs the cutting result.

The traditional way to solve the above mentioned issues is to arrange the cutting unit 9 tohave a built-in fixed positive angle of 2 - 5 degrees relative to the first plane P1. Most often,a greater positive angle is selected than what is optimal in most operational conditionsregarding the cutting result and the cutting efficiency. This because it may be wanted to avoid a negative angle in as many situations as possible.

Since the cutting unit 9 of the lawnmower 1 according to the present disclosure is pivotallyarranged relative to the lawnmower 1 chassis, a lawnmower 1 is provided having conditionsfor a more advantageous angle between the cutting plane PC and the first plane P1 atvarying cutting conditions. Accordingly, a lawnmower 1 is provided having conditions for animproved cutting result, an improved cutting efficiency, and a reduced cutting resistance atdifferent cutting conditions. This because the cutting unit 9 may be pivoted from the firstposition so as to obtain a more advantageous angle between the cutting plane PC and thefirst plane P1 at varying cutting conditions. Moreover, a lawnmower 1 is provided havingconditions for avoiding a negative angle between the cutting plane PC and the first plane P1.This because the cutting unit 9 may be pivoted so as to avoid a negative angle between the cutting plane PC and the first plane P1 during operation of the lawnmower 1.

Since the lawnmower 1 has conditions for a more advantageous angle between the cuttingplane PC and the first plane P1 at varying cutting conditions, a lawnmower 1 is providedhaving conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower 1. ln addition, since the cutting unit 9 is pivotally arranged relative to the lawnmower 1 chassis,a more durable lawnmower 1 is provided. This because the cutting unit 9 may pivot from thefirst position upon an impact between the cutting unit 9 and an object, such as a stump, astone, a sticks, or the like. Moreover, the cutting unit 9 may pivot from the first position uponrough handling of the lawnmower 1, such as when a user carries the lawnmower1 and drops the lawnmower 1 such that the cutting unit 9 is hitting an object. 27 Since the second pivot point pp2 is arranged behind the centre axis of the cutting unit 9 seenin the fonNard direction fd of the lawnmower 1, the cutting unit 9 is pivoted to obtain a morepositive angle between the cutting plane PC and the first plane P1 when the lawnmower 1 istravelling in the reverse direction rd and the cutting unit 9 is pivoted around the second pivotpoint pp2. That is, when the lawnmower 1 is travelling in the reverse direction rd of thelawnmower 1 and reaches a portion of a lawn having greater length and/or density of thevegetation, the reaction force between the cutting unit 9 and the vegetation can apply canapply a torque onto the cutting unit 9 which can displace the cutting unit 9 towards a morepositive angle relative to the first plane P1 seen in the reverse direction rd. Likewise, whenthe lawnmower 1 is travelling in the forward direction fd of the lawnmower 1 and reaches aportion of a lawn having greater length and/or density of the vegetation, the reaction forcebetween the cutting unit 9 and the vegetation can apply can apply a torque onto the cuttingunit 9 which can displace the cutting unit 9 towards a more positive angle relative to the first plane P1 seen in the forward direction fd.

When the angle of the cutting unit 9 relative to the first plane P1 is positive, the leading edgeof the cutting unit 9, seen in the reverse direction rd of the lawnmower 1, is closerto thecutting unit 9 than the trailing edge of the cutting unit 9, seen in the moving direction fd, rd ofthe lawnmower 1. ln this manner, a lowered cutting resistance can be obtained in in themoving direction fd, rd which lowers the energy consumption of the lawnmower 1 andpotentially prolongs the available operational time of the lawnmower 1. ln addition, due tothese features, a more constant cutting resistance can be obtained when mowing a lawn having varying length and/or density of the of the vegetation.

Moreover, due to these features, a lawnmower 1 is provided capable of obtaining the sameadvantageous positive angle between the cutting plane PC and the first plane P1 duringmovement in the reverse direction rd as when moving in the fonNard direction fd.Accordingly, a lawnmower 1 is provided capable of operating equally good in both travel directions fd, rd.

Furthermore, too big positive angles between the cutting plane PC and the first plane P1 canbe avoided due to the a least one resilient element 11, 12 being configured to bias the cutting unit 9 towards the first position.

According to some embodiments of the present disclosure, the first pivot point pp1 may bearranged in front of the leading edge of the cutting unit 9 seen in the forward direction fd.

Purely as examples, according to such embodiments, the first pivot point pp1 may be 28 arranged at a distance d1 from the centre axis ca within the range of 1.05 to 2 times theradius r of the cutting unit 9, or within the range of 1.1 to 1.7 times the radius r of the cuttingunit 9. Likewise, the second pivot point pp2 may be arranged in front of the leading edge ofthe cutting unit 9 seen in the reverse direction rd. Purely as examples, according to suchembodiments, the second pivot point pp2 may be arranged at a distance d2 from the centreaxis ca within the range of 1.05 to 2 times the radius r of the cutting unit 9, or within the rangeof 1.1 to 1.7 times the radius r of the cutting unit 9. According to such embodiments, thedistance D1, D2 between the leading edge of the cutting unit 9 and the first p|ane P1 can begreater when the cutting unit 9 is in a second or third position as compared to when thecutting unit 9 is in the first position. Thereby, an automatic adaptation of the cutting height ofthe lawnmower 1 is provided circumventing the need for costly and complex components andarrangements, such as sensors, motors, and the like for obtaining an automatic adaptation of the cutting height of the lawnmower.

Fig. 5 schematically illustrates a chassis member 3' according to some further embodimentsof a lawnmower. The lawnmower may be a lawnmower 1 according to the embodiments illustrated in Fig. 1. The chassis member 3' illustrated in Fig. 5 comprises the same features,functions, and advantages as the chassis member 3' explained with reference to Fig. 2 - Fig. 4, with some differences explained below.

According to the embodiments illustrated in Fig. 5, the lawnmower 1 comprises an actuatorassembly 31 configured to pivot the cutting unit 9 relative to the lawnmower chassis 3 so as to change the angle between the cutting p|ane PC and the first p|ane P1.

According to the illustrated embodiments, the holding member 15 of the chassis member 3'is hinged at a pivot point pp1. ln this manner, the cutting unit 9 is pivotally arranged relativeto the lawnmower chassis 3 around the pivot point pp1. The pivot point pp1 is arranged infront of a centre axis ca of the cutting unit 9 seen in a forward direction fd of the lawnmower1. Moreover, the pivot point pp1 is arranged such that the cutting p|ane PC is locatedbetween the pivot point pp1 and the first p|ane P1. Furthermore, according to the illustratedembodiments, the pivot point pp1 is arranged at a distance d1 from the centre axis ca of thecutting unit 9 substantially corresponding to the radius r of the cutting unit 9. The distance d1is measured in a p|ane parallel to the cutting p|ane PC. The radius r of the cutting unit 9 ismeasured in the cutting p|ane PC from the centre axis ca of the cutting unit 9 to a radial outerperiphery 9' of the cutting unit 9. According to the illustrated embodiments, the radial outerperiphery 9' of the cutting unit 9 corresponds to a radial outer periphery of the cutting members 22 of the cutting unit 9. According to further embodiments, the pivot point pp1 may 29 be arranged at a distance d1 from the centre axis ca within the range of 0.5 to 1.5 times theradius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cutting unit 9.

As understood from the above, the actuator assembly 31 is configured to pivot the cuttingunit 9 relative to the lawnmower chassis 3 around the pivot point pp1 so as to change theangle between the cutting plane PC and the first plane P1. ln Fig. 5, the cutting unit 9 isi||ustrated in a position in which the cutting plane PC is parallel to the first plane P1. Theactuator assembly 31 may thus pivot the cutting unit 9 around the pivot point pp1 to obtain apositive angle of the cutting plane PC relative to the first plane P1, seen in the forwarddirection fd of the lawnmower indicated in Fig. 5. Moreover, according to the i||ustratedembodiments, the actuator assembly 31 can also pivot the cutting unit 9 around the pivotpoint pp1 to obtain a negative angle of the cutting plane PC relative to the first plane P1,seen in the forward direction fd of the lawnmower. This can be advantageous when mowingin a reverse direction rd of the lawnmower, as is further explained herein. However,according to further embodiments, the actuator assembly 31 may only be able to pivot thecutting unit 9 around the pivot point pp1 to obtain positive angles of the cutting plane PCrelative to the first plane P1, seen in the forward direction fd of the lawnmower. According tosuch embodiments, the chassis member 3' may comprise a stop surface preventing pivotingof the holding member 15 to positions in which a negative angle is obtained between thecutting plane PC relative to the first plane P1, seen in the forward direction fd of the lawnmower.

According to the i||ustrated embodiments, the actuator assembly 31 is a linear electricalactuator assembly 31. The actuator assembly 31 may comprise an electric motor or servo,which may be operably connected to a screw, such as a roller screw, or the like. Moreover,the actuator assembly 31 may comprise another type of electro-mechanical actuator.Furthermore, according to some embodiments of the present disclosure, the actuatorassembly 31, as referred to herein, may comprise a purely mechanical actuator assembly allowing a user to adjust the angle between the cutting plane PC and the first plane P1.

According to the i||ustrated embodiments, the lawnmower 1 comprises an input unit 33 and acontrol arrangement 35. The control arrangement 35 is configured to control the actuatorassembly 31 to pivot the cutting unit 9 to a set angle relative to the lawnmower chassis 3based on data from the input unit 33. Accordingly, the control arrangement 35 is configuredto control the actuator assembly 31 adjust the angle between the cutting plane PC and the first plane P1 based on data from the input unit 33. According to some embodiments, the input unit 33 allows input from a user. That is, according to some embodiments, the input unit33 allows a user to select a wanted angle between the cutting plane PC and the first planeP1, or allows a user to select between different modes or programs representing differentpriorities between requirements such as cutting speed, energy consumption, and cuttingresult. As an example, the input unit 33 may allow a user to select a mode or programprioritizing cutting speed and/or energy consumption. When such a mode or program isselected, the control arrangement 35 may control the actuator assembly 31 to pivot thecutting unit 9 to obtain a greater angle of the cutting plane PC relative to the first plane P1.As another example, the input unit 33 may allow a user to select a mode or programprioritizing cutting result. When such a mode or program is selected, the control arrangement35 may control the actuator assembly 31 to pivot the cutting unit 9 to obtain a smaller angleof the cutting plane PC relative to the first plane P1. According to these embodiments, theinput unit 33 may comprise one or more of a button, a switch, a touch sensitive screen, or thelike. As an alternative, or in addition, the input unit 33 may comprise a communication unitconfigured to receive data from an external device, such as a computer, a computer tablet, asmartphone, or the like. Due to these features, a more user friendly lawnmower is providedcapable of allowing a user to prioritize between cutting result, cutting speed, and energy consumption.

According to some embodiments of the present disclosure, the control arrangement 35 maybe configured to control the actuator assembly 31 to pivot the cutting unit 9 to obtain anegative angle between the cutting plane PC and the first plane P1, seen in the forwarddirection fd of the lawnmower, when the lawnmower 1 is mowing in the reverse direction rd ofthe lawnmower, or when the lawnmower 1 is about to mow in the reverse direction rd of thelawnmower. ln this manner, a positive angle can be obtained between the cutting plane PCand the first plane P1, seen in the reverse direction rd of the lawnmower. According to theseembodiments, the lawnmower may comprise an adjustment mechanism capable of adjustingthe mounting position of the chassis member 3' relative to the lawnmower chassis 3indicated in Fig. 1 so as to adjust the distance between the cutting plane PC of the cuttingunit 9 and the first plane P1. Moreover, according to these embodiments, the controlarrangement 35 may increase the height of the chassis member 3' relative to the first planeP1 when controlling the actuator assembly 31 to pivot the cutting unit 9 to obtain the negativeangle between the cutting plane PC and the first plane P1, seen in the forward direction fd ofthe lawnmower during reverse mowing of the lawnmower 1. ln this manner, the cutting heightcan be maintained when cutting in the reverse direction rd of the lawnmower in the manner described above. 31 According to further embodiments, the control arrangement 35 may be configured to controlthe actuator assembly 31 to pivot the cutting unit 9 to a position in which the cutting plane PCis substantially parallel to the first plane P1 when the lawnmower 1 is mowing in the reversedirection rd of the lawnmower, or when the lawnmower 1 is about to mow in the reversedirection rd of the lawnmower. ln this manner, a negative angle can be avoided of the cuttingplane PC relative to the first plane P1 seen in the reverse direction rd when cutting in thereverse direction rd. Moreover, in this manner, the cutting height can be maintained when cutting in the reverse direction rd of the lawnmower.

The input unit 33 may be configured to obtain data representative of a current cuttingresistance, wherein the control arrangement 35 is configured to determine the set anglebased on the current cutting resistance. The control arrangement 35 may be configured todetermine the set angle based on the current cutting resistance such that an increased angleis obtained between the cutting plane PC and the first plane P1 with increased cuttingresistance and such that a decreased angle is obtained bet\Neen the cutting plane PC andthe first plane P1 with decreased cutting resistance. ln this manner, the angle between thecutting plane PC and the first plane P1 can be adjusted in an automatic manner based on thelength and density of the vegetation being cut and based on the travel speed of the lawnmower.

According to the illustrated embodiments, the lawnmower comprises an electric motor 17configured to drive, i.e. rotate, the cutting unit 9 during operation of the lawnmower 1. Asindicated in Fig. 5, the input unit 33 may be configured to obtain data representative of thecurrent cutting resistance by monitoring electrical quantities of the electric motor 17. Theelectrical quantities of the electric motor 17 may comprise an electric current and/or anelectric voltage supplied to the electric motor 17. ln this manner, data representative of the current cutting resistance can be obtained in a simple, reliable, and cost-efficient manner.

As is further explained herein, according to some embodiments, the input unit 33 may beconfigured to obtain data representative of a current position of the lawnmower, and whereinthe control arrangement 35 is configured to determine the set angle based on the current position of the lawnmower.

Fig. 6 illustrates a lawnmower 1 according to some embodiments of the present disclosure.The lawnmower 1 illustrated in Fig. 6 comprises a chassis member 3' according to theembodiments illustrated in Fig. 5. Therefore, below, simultaneous reference is made to Fig. 5 and Fig. 6. The lawnmower1 illustrated in Fig. 6 is illustrated as mowing a lawn comprising a 32 first area A1 and a second area A2. The lawnmower 1 comprises an input unit 33 configuredto obtain data representative of a current position of the lawnmower 1. The input unit 33 maybe configured to obtain data from, or may comprise, one or more positioning units configuredto estimate a current position of the robotic lawnmower 1, such as for example a spacebased satellite navigation system such as a Global Positioning System (GPS), The RussianGLObal NAvigation Satellite System (GLONASS), European Union Galileo positioningsystem, Chinese Compass navigation system, or Indian Regional Navigational SatelliteSystem. As an alternative, or in addition, the input unit 33 may be configured to obtain datafrom, or may comprise, one or more positioning units utilizing a local reference source, suchas a local sender and/or a wire, to estimate or verify a current position of the robotic lawnmower 1.

According to the illustrated embodiments, the first area A1 represents an area having ahigher demand on lawn appearance than the second area A2. The first area A1 may forexample represent an area in which a user demands a higher lawn appearance, such as anarea close to a house, an area close to a walkway, an area used for sports activities, or thelike. The second area A2 may for example represent an area in which a user demands alower lawn appearance, such as an area further away from a house, an area normally visually hidden by objects, such as a garage, shrubs, trees, garden furniture, or the like.

As explained above, according to embodiments herein, the control arrangement 35 isconfigured to determine the set angle based on the current position of the lawnmower 1. lnthe above given example, the control arrangement 35 may determine a set angle to obtain asmall positive angle between the cutting plane PC and the first plane P1 when thelawnmower is in the first area A1. When the lawnmower 1 reaches the second area A2, thecontrol arrangement 35 determine a set angle to obtain a greater positive angle between thecutting plane PC and the first plane P1. ln this manner, the first area A1 is cut with higherprecision, i.e. with a higher cutting result, than the second area A2, and the second area A2is cut with a lower cutting resistance than the first area A1, i.e. with a reduced energyconsumption. ln addition, due to the greater positive angle, the second area A2 can be cutfaster. ln this manner, the lawnmower1 allows a user to make different prioritizationsbetween cutting result, energy consumption, and cutting speed of different areas A1, A2 of a lawn.

The control arrangement 35 may be configured to receive data representative of differentareas A1, A2 of a lawn and cutting requirements thereof from an external device, such as a computer, a computer tablet, a smartphone, or the like. Such data may be sent wirelessly to 33 the control arrangement 35 of the lawnmower 1. As an alternative, or in addition, thelawnmower 1 may comprise a touch sensitive screen, or the like, allowing input of different areas A1, A2 of a lawn and cutting requirements thereof.

The control arrangement 35 may comprise a calculation unit which may take the form ofsubstantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digitalsignal processing (digital signal processor, DSP), a Central Processing Unit (CPU), aprocessing unit, a processing circuit, a processor, an Application Specific Integrated Circuit(ASIC), a microprocessor, or other processing logic that may interpret and executeinstructions. The herein utilised expression “calculation unit” may represent a processingcircuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 35 may further comprise a memory unit, wherein the calculationunit may be connected to the memory unit, which may provide the calculation unit with, forexample, stored program code and/or stored data which the calculation unit may need toenable it to do calculations. The calculation unit may also be adapted to store partial or finalresults of calculations in the memory unit. The memory unit may comprise a physical deviceutilised to store data or programs, i.e., sequences of instructions, on a temporary orpermanent basis. According to some embodiments, the memory unit may compriseintegrated circuits comprising silicon-based transistors. The memory unit may comprise e.g.a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile ornon-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM(Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 35 is connected to components of the robotic lawnmower 1 forreceiving and/or sending input and output signals. These input and output signals maycomprise waveforms, pulses, or other attributes which the input signal receiving devices candetect as information and which can be converted to signals processable by the controlarrangement 35. These signals may then be supplied to the calculation unit. One or moreoutput signal sending devices may be arranged to convert calculation results from thecalculation unit to output signals for conveying to other parts of the robotic lawnmower'scontrol system and/or the component or components for which the signals are intended.Each of the connections to the respective components of the robotic lawnmower 1 for receiving and sending input and output signals may take the form of one or more from 34 among a cable, a data bus, e.g. a CAN (controller area network) bus, or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the robotic lawnmower 1 comprises a control arrangement 35but might alternatively be implemented wholly or partly in two or more control arrangements or t\No or more control units.

According to some embodiments of the present disclosure, the embodiments of the chassismember 3' explained with reference to Fig. 2 - Fig. 4 may be combined with embodiments ofthe chassis member 3' explained with reference to Fig. 5 and Fig. 6. According to suchembodiments, the lawnmower 1 may comprise an actuator assembly 31 configured to pivotthe cutting unit 9 relative to the lawnmower chassis 3 to a default position, such as a firstposition explained herein, wherein the cutting unit 9 may be configured to pivot from thedefault position for example based on a load exerted on the cutting unit 9 by vegetation.Moreover, according to such embodiments, the chassis member 15 may comprise one ormore seats s1, s2 and a holding member 15 configured to abut against the one or more seats s1, s2, as explained with reference to Fig. 3 and Fig. 4.

Moreover, in embodiments wherein the lawnmower 1 comprises an actuator assembly 31 configured to pivot the cutting unit 9 relative to the lawnmower chassis 3 so as to change theangle between the cutting plane PC and the first plane P1, the cutting unit 9 may be pivotallyarranged relative to the lawnmower chassis 3 around a second pivot point pp2, as explained with reference to Fig. 3 and Fig. 4. lt is to be understood that the foregoing is illustrative of various example embodiments andthat the invention is defined only by the appended claims. A person skilled in the art willrealize that the example embodiments may be modified, and that different features of theexample embodiments may be combined to create embodiments other than those describedherein, without departing from the scope of the present invention, as defined by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one ormore stated features, elements, steps, components, or functions but does not preclude thepresence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

The wording “substantially parallel to", as used herein, may encompass that the angle between the objects referred to is less than 2 degrees.

The wording “substantially corresponding to", as used herein, may encompass that theaspects, objects, distances, or measurements referred to deviates less than 7% from eachother.

Claims

1. 36 CLAll\/IS 1. A lawnmower (1) comprising: - a lawnmower chassis (3), - lawnmower support members (5, 5') configured to abut against a ground surface (7)in a first plane (P1) during operation of the lawnmower (1), and - a cutting unit (9) configured to operate in a cutting plane (PC), wherein the cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) to pivot between a first position and a second position, and wherein theangle between the cutting plane (PC) and the first plane (P1) is different when thecutting unit (9) is in the second position than when the cutting unit (9) is in the first position. _ The lawnmower (1) according to claim 1, wherein the cutting plane (PC) is substantially parallel to the first plane (P1) when the cutting unit (9) is in the first position. The lawnmower (1) according to claim 1 or 2, wherein the angle between the cuttingplane (PC) and a |ongitudina| direction (ld) of the lawnmower (1) is different when thecutting unit (9) is in the second position than when the cutting unit (9) is in the first position. _ The lawnmower (1) according to any one of the preceding claims, wherein the cutting unit (9) is configured to pivot from the first position based on a load exerted on the cutting unit (9) by vegetation. The lawnmower (1) according to any one of the preceding claims, wherein the cuttingunit (9) is configured to pivot from the first position by a reaction force obtained between the cutting unit (9) and vegetation during operation of the lawnmower (1 ). The lawnmower (1) according to any one of the preceding claims, wherein the cuttingunit (9) is configured to pivot from the first position when a reaction force between thecutting unit (9) and vegetation exceeds a predetermined thresho|d value during operation of the lawnmower (1 ). The lawnmower (1) according to any one of the preceding claims, wherein thelawnmower (1) comprises a least one resilient element (11, 12) configured to bias the cutting unit (9) towards the first position. 10. 11. 1

2. 1

3. 1

4. 37 The lawnmower (1) according to any one of the preceding claims, wherein thelawnmower (1) comprises a least one damper (13) configured to damp movement between the cutting unit (9) and the lawnmower chassis (3). The lawnmower (1) according to any one of the preceding claims, wherein the cuttingunit (9) is pivotally arranged relative to the lawnmower chassis (3) around a first pivotpoint (pp1), and wherein the first pivot point (pp1) is arranged in front of a centre axis (ca) of the cutting unit (9) seen in a forward direction (fd) of the lawnmower (1). The lawnmower (1) according to claim 9, wherein the first pivot point (pp1) is arranged ata distance (d1) from the centre axis (ca) within the range of 0.5 to 1.5 times a radius (r)of the cutting unit (9), or within the range of 0.8 to 1.2 times the radius (r) of the cuttingunit (9). The lawnmower (1) according to claim 9 or 10, wherein the vertical distance (vd1)between the first pivot point (pp1) and cutting members (22) of the cutting unit (20) iswithin the range of 15% - 60%, or 25% - 45% of a radius (r) of the cutting unit (9). The lawnmower (1) according to any one of the preceding claims, wherein the cuttingunit (9) is pivotally arranged relative to the lawnmower chassis (3) around a second pivotpoint (pp2), and wherein the second pivot point (pp2) is arranged behind a centre axis (ca) of the cutting unit (9) seen in a forward direction (fd) of the lawnmower (1). The lawnmower (1) according to claim 12, wherein the second pivot point (pp2) isarranged at a distance (d2) from the centre axis (ca) within the range of 0.5 to 1.5 timesa radius (r) of the cutting unit (9), or within the range of 0.8 to 1.2 times the radius (r) ofthe cutting unit (9). The lawnmower (1) according to any one of the preceding claims, wherein thelawnmower (1) comprises a holding member (15), wherein the cutting unit (9) is pivotallyarranged relative to the lawnmower chassis (3) via the holding member (15), andwherein the holding member (15) is configured to abut against a first seat (s1) when thecutting unit (9) is in the first position, and is configured to be lifted from the first seat (s1) when the cutting unit (9) is pivoted from the first position. 1

5. 1

6. 1

7. 1

8. 1

9. 20. 21. 22. 23. 24. 38 The lawnmower (1) according to claim 14, wherein the holding member (15) isconfigured to abut against a second seat (s2) when the cutting unit (9) is in the first position. The lawnmower (1) according to claim 9 and 15, wherein the abutting contact between the holding member (15) and the second seat (s2) forms the first pivot point (pp1). The lawnmower (1) according to claim 12 and claim 15 or 16, wherein the abutting contact bet\Neen the holding member (15) and the first seat (s1) forms the second pivot point (pp2). The lawnmower (1) according to claim 17, wherein the cutting unit (9) is configured to belifted from the second seat (s2) when the cutting unit (9) is pivoted around the second pivot point (pp2) from the first position. The lawnmower (1) according to any one of the preceding claims, wherein thelawnmower (1) comprises a driving unit (17) configured to drive the cutting unit (9) duringoperation of the lawnmower (1 ), and wherein the driving unit (17) is arranged to pivotwith the cutting unit (9). The lawnmower (1) according to any one of the preceding claims, wherein the cuttingunit (9) comprises a cutting disc (20) provided with a number of cutting members (22) arranged at a periphery (20') of the cutting disc (20). The lawnmower (1) according to claim 20, wherein the cutting members (22) are pivotally arranged to the cutting disc (20). The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) is a self-propelled autonomous robotic lawnmower (1 ). The lawnmower (1) according to any one of the preceding claims, wherein thelawnmower (1) comprises an actuator assembly (31) configured to pivot the cutting unit(9) relative to the lawnmower chassis (3) so as to change the angle between the cuttingplane (PC) and the first plane (P1). The lawnmower (1) according to claim 23, wherein the lawnmower (1) comprises an input unit (33) and a control arrangement (35), and wherein the control arrangement (35) 25. 26. 27. 28. 29. 39 is configured to control the actuator assembly (31) to pivot the cutting unit (9) to a set angle relative to the lawnmower chassis (3) based on data from the input unit (33). The lawnmower (1) according to claim 24, wherein the input unit (33) is configured toobtain data representative of a current position of the lawnmower (1 ), and wherein thecontrol arrangement (35) is configured to determine the set angle based on the current position of the lawnmower (1 ). The lawnmower (1) according to claim 24 or 25, wherein the input unit (33) is configuredto obtain data representative of a current cutting resistance, and wherein the controlarrangement (35) is configured to determine the set angle based on the current cutting resistance. The lawnmower (1) according to claim 26, wherein the lawnmower (1) comprises anelectric motor (17) configured to drive the cutting unit (9) during operation of thelawnmower (1 ), and wherein the input unit (33) is configured to obtain datarepresentative of the current cutting resistance by monitoring electrical quantities of the electric motor (17). The lawnmower (1) according to any one of the claims 23 - 27, wherein the actuator assembly (31) is an electrical actuator assembly (31 ). A lawnmower (1) comprising: - a lawnmower chassis (3), - lawnmower support members (5, 5') configured to abut against a ground surface (7)in a first plane (P1) during operation of the lawnmower (1), and - a cutting unit (9), wherein the cutting unit (9) is movably arranged relative to the lawnmowerchassis (3) to move between a first position and a second position, and wherein thedistance (D2) between at least a portion (9') of the cutting unit (9) and the first plane(P1) is different when the cutting unit (9) is in the second position than when thecutting unit (9) is in the first position, andwherein the cutting unit (9) is configured to move from the first position to the second position by a reaction force obtained betvveen the cutting unit (9) and vegetation during operation of the lawnmower (1).