Robotic Lawnmower Cutting Rotation Control for Clipping Direction

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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 their operational efficiency and lawn appearance.

Innovation Solution

A control arrangement that navigates the lawnmower along specific paths based on the rotation direction of its cutting unit, allowing grass clippings to be ejected either towards previously mowed areas to reduce energy consumption and improve cutting results, or towards upcoming areas to achieve a more mulched cutting result and faster decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the robotic lawnmower cuts grass in a conventional manner without controlling clipping ejection direction, then the cutting operation is simple, but energy consumption increases and cutting result uniformity deteriorates

Engineering Contradiction:

Improveenergy consumptionVSAvoidcontrol arrangement complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The control arrangement monitors the navigation path and cutting unit rotation direction, and adjusts the rotation direction based on feedback from the mowing pattern to optimize clipping ejection. This closed-loop control reduces energy consumption by preventing re-cutting while maintaining systematic operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The cutting unit rotation direction is dynamically adjusted based on the navigation path and mowing pattern rather than operating in a fixed direction. This dynamic adaptation allows the system to optimize clipping ejection in real-time, reducing energy consumption and improving cutting uniformity.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If grass clippings are ejected toward uncut areas, then the cutting operation is simple, but cutting result uniformity deteriorates due to flattened grass and bent straws

Engineering Contradiction:

Improvecutting result uniformityVSAvoidnavigation and control complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The control arrangement plans the navigation path and cutting unit rotation direction in advance to ensure clippings are ejected toward already-mowed areas. This preliminary planning prevents grass flattening and bending before the cutting operation occurs, maintaining cutting result uniformity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the navigation path and mowing pattern to dynamically adjust clipping ejection direction, ensuring clippings are consistently directed toward already-mowed areas throughout the operation, thereby maintaining uniform cutting results.

Inventive Principle:

Principle #23Feedback

3Duration of action of moving object

If the robotic lawnmower operates without controlling clipping ejection direction, then the operation is straightforward, but operational time is limited due to higher energy consumption

Engineering Contradiction:

Improveoperational timeVSAvoidcontrol system complexity

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The control arrangement continuously monitors navigation path and cutting unit rotation direction, adjusting the rotation direction based on feedback to optimize clipping ejection. This reduces energy consumption and extends operational time between battery charges.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The cutting unit rotation direction is dynamically adjusted based on real-time navigation path and mowing pattern data, allowing the system to optimize energy efficiency during operation and extend operational duration.

Inventive Principle:

Principle #15Dynamics

4Loss of time

If grass clippings are not properly managed, then the cutting operation is simple, but decomposition time increases and lawn appearance deteriorates

Engineering Contradiction:

Improvedecomposition timeVSAvoidcontrol arrangement complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

Instead of treating grass clipping ejection as a simple byproduct, the system strategically directs clippings toward already-mowed areas where they can decompose into mulch. This converts what could be a harmful factor (clippings on uncut grass) into a beneficial one (nutrient-rich mulch on mowed areas), accelerating decomposition and improving lawn appearance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20230042864A1Control arrangement for robotic lawnmower and method of operating robotic lawnmower

Publication Date: 2023.02.09 HUSQVARNA AB

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 (d1, 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.