Tracked Self-Moving Mower Turning Control With Variable Ground Contact

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Solution Overview

Problem

Existing track-type self-moving devices, such as mowers, suffer from lawn damage, large minimal turning radius, and poor trafficability due to the track's grounding during turns, which also increases torque requirements.

Innovation Solution

A self-moving device with a support structure that extends and retracts to maintain a smaller grounding length during turns, reducing contact with the lawn and allowing for a smaller turning radius and improved trafficability, using a control module to manage the support structure's extension and retraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the track remains grounded during turning, then the device maintains stability, but the lawn is damaged and the turning radius is large

Engineering Contradiction:
Improvelawn damageVSAvoiddevice stability
Core Design Contradiction:
Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The support structure dynamically changes its state between extended and retracted positions. During turning operations, it extends to lift the track off the ground, reducing lawn damage. During straight movement, it retracts to maintain stability. This dynamic adjustment resolves the contradiction between minimizing lawn damage and maintaining device stability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The support structure extends in advance before the turning operation begins, proactively preventing track-lawn contact during the turn. This preliminary action ensures the track is already elevated when turning starts, thus preventing lawn damage before it occurs.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the track grounding length is reduced during turning, then the turning radius is smaller and trafficability is improved, but the device complexity increases

Engineering Contradiction:
ImprovetrafficabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The support structure acts as an intermediary element between the track and the ground. It mediates the interaction by providing additional support points that allow the track to be lifted during turning, enabling smaller turning radii without directly modifying the track or ground.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The support structure divides the single-point support function into multiple support points distributed along the device. This segmentation allows different parts of the device to perform different functions - the support structure handles lifting during turns while the track handles propulsion and straight-line stability.

Inventive Principle:
Principle #1Segmentation

3Force

If the support structure is extended during turning, then the track friction with lawn is reduced, but the device complexity increases

Engineering Contradiction:
Improvetrack frictionVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The support structure extracts the support function from the track-ground contact system. By providing an alternative support mechanism that lifts the track off the ground during turning, it removes the harmful friction interaction between the track and lawn while maintaining the necessary support function.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3406119B1Self-moving device and method for controlling self-moving device
Publication Date: 2026.01.14 POSITEC POWER TOOLS (SUZHOU) CO LTD
  • EP3406119B1 patent drawingFigure 1

AI summary

A self-moving device and a control method for a self-moving device are disclosed. The self-moving device includes a moving module, a control module and an adjusting device. The moving module includes a track, driven by a drive motor to drive the self-moving device to move. The control module controls the adjusting device to adjust a grounding length of the track, such that the grounding length of the track when the self-moving device turns is smaller than that of the track when the self-moving device moves straightly. The control method for a self-moving device includes the steps: controlling to reduce the grounding length of the track before the self-moving device is controlled to turn; and controlling to increase the grounding length of the track after the self-moving device is controlled to finish the turning. In the self-moving device, since the grounding length of the track during turning is smaller, a contact area between the track and a lawn is smaller, the damage of the track to the lawn can be reduced, a minimal turning radius of the self-moving device can be further reduced, the trafficability of the machine is improved, and meanwhile the drive force of the motor can be reduced.