Robotic Lawnmower Cutting Rotation for Clipping Ejection Control
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Solution Overview
Problem
Self-propelled robotic lawnmowers face issues with energy consumption, cutting result uniformity, and grass clipping decomposition, which affect visual appearance and operational efficiency.
Innovation Solution
A control arrangement that reversibly sets the rotation direction of the cutting unit based on the location of previous or upcoming mowing strokes relative to the lawnmower, allowing grass clippings to be ejected towards already mowed or upcoming areas, thereby optimizing energy consumption and cutting results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cutting unit rotates in a fixed direction, then the structure is simple, but grass clippings are ejected towards uncut areas causing poor cutting uniformity and visual appearance
Solution Approach 1:
The cutting unit's rotation direction is made dynamic and reversible, allowing it to switch between clockwise and counter-clockwise rotation based on the mowing pattern. This enables grass clippings to be ejected towards already mowed areas rather than uncut areas, significantly improving cutting uniformity and visual appearance without requiring complex additional mechanical structures
Solution Approach 2:
The control arrangement uses feedback from the mowing stroke pattern (previous or upcoming adjacent strokes) to automatically adjust the cutting unit's rotation direction. This closed-loop control ensures optimal clipping ejection direction is selected based on real-time operational context, maintaining high cutting quality while keeping the control logic manageable
2Productivity
If grass clippings are ejected towards uncut areas, then the cutting process is simple, but decomposition is slow and visual appearance deteriorates
Solution Approach 1:
The system performs preliminary action by ejecting grass clippings towards already mowed areas where the lawn surface is prepared and uniform. This preliminary placement of clippings in suitable locations accelerates decomposition and improves visual appearance, as clippings are distributed on freshly mowed surfaces rather than being scattered on uncut tall grass
3Manufacturing precision
If the cutting unit rotation direction is constantly changed, then clipping ejection is optimized, but energy consumption increases
Solution Approach 1:
The cutting unit's rotation direction is changed periodically based on the completion of mowing strokes or approach to upcoming strokes, rather than continuously. This periodic reversal strategy optimizes clipping ejection direction while minimizing unnecessary direction changes, thereby reducing energy consumption while maintaining high cutting quality
Data Source
Figure 1~2
Figure 3~5
AI summary
The present invention relates to a control arrangement (1) for a self-propelled robotic lawnmower (3) having a cutting unit (5, 6) configured to rotate during operation of the lawnmower (3). The control arrangement (1) is configured to navigate the lawnmower (3) along a navigation path (7) comprising adjacent mowing strokes (S, Sp, Su). The control arrangement (1) is configured to set a rotation direction (rl, r2) of the cutting unit (5, 6) based on the navigation path (7), or is configured to select the navigation path (7) based on a rotation direction (rl, r2) of the cutting unit (5, 6). By adapting the rotation direction (rl, r2) or the navigation path (7), the direction (dl d2) to which grass clippings are ejected, i.e. towards the previous mowing stroke (Sp) or to a future mowing stroke (Su) is controlled thereby reducing energy consumption or grass decomposition time.