Robotic Lawn Mower Cutting Disc Layout for Boundary Grass
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Solution Overview
Problem
Robotic lawn mowers have limited ability to cut grass close to objects and borders due to the cutting unit being hindered by the mower body and wheels, and they struggle with cutting relatively long grass due to safety concerns.
Innovation Solution
The cutting disc is positioned to move laterally in an arcuate manner when the drive wheels are driven in different directions, allowing the mower to cut close to boundaries and objects, with a control unit controlling the mower's movement and rotation to perform arcuate movements and adjust cutting height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cutting unit is arranged at the underside of the mower body, then the mower body provides structural support and protection, but the mower body and wheels hinder the cutting unit from reaching grass close to objects and borders
Solution Approach 1:
The cutting system is segmented into a main cutting disc for general cutting and a separate side cutting disc for boundary cutting. The side cutting disc is positioned on the side of the mower body and can be independently controlled to extend laterally, allowing grass close to boundaries to be cut without moving the entire mower body forward.
Solution Approach 2:
The cutting capability is extended from the vertical dimension (underneath the mower body) to the lateral dimension (side of the mower body). The side cutting disc is arranged to move laterally in an arcuate manner, enabling the cutting unit to reach grass close to objects and borders by utilizing lateral movement rather than only forward movement.
2Reliability
If the mower body is kept compact for safety, then safety is improved, but ground clearance height is limited preventing cutting of relatively long grass
Solution Approach 1:
The cutting system is divided into a main cutting disc for general cutting and a side cutting disc for boundary cutting. The side cutting disc is positioned laterally, allowing the mower body to remain compact while still achieving the ability to cut long grass near boundaries through the extended lateral reach.
Solution Approach 2:
The side cutting disc is made dynamically positionable, capable of moving laterally in an arcuate manner when drive wheels are driven in different rotation directions. This dynamic positioning allows the cutting disc to reach long grass near boundaries only when needed, maintaining a compact body structure for safety during normal operation.
3Productivity
If the cutting disc is positioned to reach close to boundaries, then cutting coverage near objects is improved, but the risk of interference with obstacles increases
Solution Approach 1:
The side cutting disc is designed to be dynamically positionable, moving laterally in an arcuate manner only when the drive wheels are driven in different rotation directions. This controlled dynamic movement allows the cutting disc to reach close to boundaries for improved cutting coverage while minimizing unnecessary lateral movement that could cause interference with obstacles.
Solution Approach 2:
The control system monitors the position and movement of the side cutting disc, adjusting its lateral movement based on detected boundary conditions and obstacle proximity. This feedback mechanism ensures the cutting disc reaches close to boundaries for improved coverage while automatically reducing movement when obstacle interference risk is detected.
Data Source
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AI summary
The present disclosure relates to a robotic lawn mower (100) having a first end portion (101) and a second end portion (102), and comprising a body (140), at least two drive wheels (130a, 130b), at least one swivelable wheel (131a, 131b), a rotatable grass cutting disc (160) having a rotation axis (152), and at least two electric motor arrangements (150, 165). At least two drive wheels (130a, 130b) have a drive wheel axis (145) with a center (146) and are drivably connected to a first electric motor arrangement (150), where at least one swivelable wheel (131a, 131b) has a corresponding swivel axis (153,154). A swivel attachment axis (151), running through at least one swivel axis (153,154) and being parallel to the drive wheel axis (145), is positioned between the second end portion (102) and the drive wheel axis (145). The cutting disc (160) is drivably connected to a second electric motor arrangement (165), wherein the cutting disc (160) at least partly is positioned between the swivel attachment axis (151) and the second end portion (102).