Robotic Lawnmower Wheel Motion Sensing for Stuck Detection

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Solution Overview

Problem

Autonomous working devices, such as robot lawn mowers, face challenges in detecting stuck states due to spinning drive wheels on slippery surfaces, leading to potential damage and reduced soil tillage performance.

Innovation Solution

Incorporating a sensor unit with inductive, magnetic, or optical sensor elements to detect translational and rotational movements of wheel units relative to the housing, allowing the control unit to identify stuck states and initiate countermeasures, such as changing direction or speed, to restore mobility and prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If drive wheels spin on slippery surfaces to maintain mobility, then the device can continue moving, but the drive wheels cause surface damage and reduce soil tillage performance

Engineering Contradiction:
ImprovemobilityVSAvoidsurface damage
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The sensor unit detects wheel movements in advance to identify stuck states before significant surface damage occurs. The control unit then initiates countermeasures such as changing direction or speed proactively, preventing the harmful spinning effect from continuing and causing additional damage to the surface.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sensor unit continuously monitors wheel unit movements and provides feedback to the control unit. This feedback loop enables the system to detect stuck states in real-time and automatically adjust drive wheel operations, stopping the harmful spinning action when surface damage is detected and restoring normal tillage performance.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If sensor units are added to detect wheel movements and identify stuck states, then surface damage is minimized, but device complexity increases

Engineering Contradiction:
Improvesurface damageVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical detection systems with sensor units that use inductive, magnetic, or optical principles to detect wheel movements. This substitution reduces mechanical complexity while enabling precise detection of stuck states to prevent surface damage.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control unit automatically processes sensor data and executes countermeasures without external intervention. The system serves itself by autonomously identifying stuck states and implementing recovery actions, minimizing the need for additional complex control mechanisms while preventing surface damage.

Inventive Principle:
Principle #25Self-service

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 rapid recognition and mitigation of stuck states, minimizing surface damage and maintaining consistent soil tillage performance by automatically adjusting the device's movement.

Implementation Method 1

sensor unit (18) for detecting a movement of the wheel unit (14, 16) relative to the housing (12)... sensor unit with inductive, magnetic, or optical sensor elements

Methodology Applied
Scientific EffectInductive sensing: Electromagnetic Induction

Implementation Method 2

sensor unit with inductive, magnetic, or optical sensor elements to detect translational and rotational movements

Methodology Applied
Scientific EffectMagnetic sensing: Hall Effect

Implementation Method 3

sensor unit with inductive, magnetic, or optical sensor elements to detect translational and rotational movements

Methodology Applied
Scientific EffectOptical sensing: Photoelectric Effect

Data Source

PatentEP3669627B1Autonomous work device
Publication Date: 2021.12.15 ROBERT BOSCH GMBH
  • EP3669627B1 patent drawingFigure 1~2
  • EP3669627B1 patent drawingFigure 3~4
  • EP3669627B1 patent drawingFigure 5~6

AI summary

The invention relates to an autonomous work device, in particular a robotic lawnmower, comprising at least one housing (12), at least one wheel unit (14, 16), in particular a drive-free wheel unit, at least one sensor unit (18) for detecting movement of the wheel unit (14, 16) relative to the housing (12), and at least one control and/or regulation unit (20) for processing signals detected by the sensor unit (18). It is proposed that the control and/or regulation unit (20) be configured to detect a stuck state and/or a jammed state based on the sensor unit's (18) detection of movement of the at least one wheel unit (14, 16) relative to the housing (12).