Robotic Lawn Mower Boundary Arc Cutting Near Lawn Edges
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Solution Overview
Problem
Robotic lawn mowers have a limited ability to cut grass close to objects and borders outside the defined cutting area boundary, resulting in uncut grass due to the mower's design hindering access and the risk of cutting outside the intended lawn edge.
Innovation Solution
A robotic lawn mower with a control unit that positions the mower to maintain a shortest distance from the boundary, allowing the cutting disc to perform an arcuate movement close to borders while preventing cutting outside the boundary, using drive wheels to turn in different directions and a navigation system for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cutting unit is arranged at the underside of the lawn mower body, then the mower can cut grass in the operation area, but the body and wheels hinder the cutting unit from reaching grass close to objects and borders
Solution Approach 1:
The cutting unit is made movable relative to the mower body through a lifting mechanism. The control unit activates this mechanism to raise the cutting unit when approaching borders, enabling the mower to cut grass close to objects and borders that would otherwise be inaccessible due to the body and wheels blocking the fixed cutting unit.
2Productivity
If the mower approaches the boundary at any angle, then it can cover the operation area efficiently, but it risks cutting outside the intended lawn edge
Solution Approach 1:
The control unit continuously monitors the mower's position relative to the boundary and the angle of approach. When detecting that the mower is approaching the boundary at an angle that would cause cutting outside the lawn edge, the control unit activates the lifting mechanism to raise the cutting unit, preventing unwanted cutting while maintaining efficient area coverage.
Solution Approach 2:
Before the mower potentially cuts outside the boundary, the control unit preemptively raises the cutting unit when detecting an unfavorable approach angle. This preliminary action prevents the harmful effect of cutting outside the intended lawn edge before it occurs.
3Manufacturing precision
If the cutting unit remains fixed at the underside, then the mower structure is simple, but uncut grass remains close to objects such as trees, stones, furniture, and building walls
Solution Approach 1:
The cutting unit transitions from a fixed position to a movable one, capable of being raised when needed. This dynamic adjustment allows the cutting unit to reach grass close to objects and borders by lifting the mower body or raising the cutting unit, eliminating uncut grass areas while adding only the necessary lifting mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective cutting of grass close to borders without crossing the boundary, regardless of the angle of approach, by strategically positioning the mower and controlling its movement to maintain a safe distance from the boundary, ensuring a clean cut within the defined area.
Implementation Method 1
An electric control signal may be transmitted through the boundary wire thereby generating an (electro-) magnetic field emanating from the boundary wire. The robotic working tool is typically arranged with one or more sensors adapted to sense the control signal.
Data Source
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AI summary
The present disclosure relates to a robotic lawn mower (100) comprising a body (140), at least two drive wheels (130a, 130b) arranged along a drive wheel axis (145) with a center (146) that is positioned between the drive wheels (130a, 130b). The robotic lawn mower (100) further comprises a control unit (110) and at least a first rotatable grass cutting disc (160). When the robotic lawn mower (100) is approaching a boundary (220) of an operation area (610), the control unit (110) is adapted to - position the robotic lawn mower (100a) such that there is a shortest distance (ds) between the center (146) and the boundary (220), and to - control the drive wheels (130a, 130b) to turn in mutually different directions such that the second end portion (102) of the robotic lawn mower (100a, 100b, 100c) performs an arcuate movement along a cutting arc (210), enabling the first cutting disc (160) to cut grass within the cutting arc (210). The boundary (220) is positioned between a border (139) and the operation area (610), and where the shortest distance (ds) admits the cutting arc (210) to have a closest arc portion (211) that is closest to the border (139) without passing the border (139).