Robotic Mower Boundary Sensing System for Distance Measurement

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Solution Overview

Problem

Existing robotic lawn mowers lack an accurate and reliable method to determine their distance from the boundary wire, which is crucial for efficient navigation and operation.

Innovation Solution

A boundary sensing system comprising a boundary driving circuit on a charging station that transmits encoded signals on a boundary wire, and four boundary sensors on the robotic mower, which use signal strength to calculate distance and angular orientation relative to the wire, with a vehicle control unit processing this information to control the mower's movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a boundary sensing system uses signal strength to determine distance, then measurement precision is improved, but device complexity increases due to multiple sensors and signal processing requirements

Engineering Contradiction:
Improvedistance measurement precisionVSAvoidboundary sensing system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The boundary sensing system is divided into four separate boundary sensors positioned at different locations on the robotic mower. Each sensor independently measures signal strength from the boundary wire, allowing the system to determine both distance and angular orientation through comparative analysis of the four sensor readings.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The boundary sensing system serves multiple functions simultaneously: it determines the distance to the boundary wire, calculates the angular orientation relative to the wire, and provides data for both navigation and area coverage optimization. This multi-functionality reduces the need for separate sensing systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If the robotic mower uses four boundary sensors to determine angular orientation, then navigation precision is improved, but ease of operation deteriorates due to complex signal processing requirements

Engineering Contradiction:
Improveangular orientation precisionVSAvoidsignal processing complexity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The vehicle control unit continuously receives signal strength readings from all four boundary sensors and uses this feedback to calculate angular orientation and adjust the mower's navigation in real-time. This closed-loop feedback system automates the complex signal processing, making the system easy to operate while maintaining high precision.

Inventive Principle:
Principle #23Feedback

3Reliability

If the boundary driving circuit transmits encoded signals on the boundary wire, then reliability of boundary detection is improved, but use of energy increases due to continuous signal transmission

Engineering Contradiction:
Improveboundary detection reliabilityVSAvoidenergy consumption of boundary driving circuit
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The boundary driving circuit transmits encoded signals in periodic pulses rather than continuous waves. This periodic transmission maintains reliable boundary detection capability while significantly reducing energy consumption compared to continuous signal transmission.

Inventive Principle:
Principle #19Periodic action

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 the robotic mower to accurately determine its proximity and orientation to the boundary wire, allowing for efficient navigation, area coverage, and preventing turf damage by ensuring precise boundary following and obstacle detection.

Implementation Method 1

a boundary sensor on a robotic mower and including an inductor receiving the encoded signal

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2572567B1Robotic mower with a boundary sensing system
Publication Date: 2016.09.14 DEERE & CO
  • EP2572567B1 patent drawingFigure 1
  • EP2572567B1 patent drawingFigure 2
  • EP2572567B1 patent drawingFigure 3

AI summary

A robotic mower boundary sensing system includes a boundary driving circuit on a charging station (105) transmitting an encoded signal on a boundary wire (103, 104); a boundary sensor (119) on a robotic mower (100) and including an inductor receiving the encoded signal; and a vehicle control unit (101) on the robotic mower (100) receiving the encoded signal from the boundary sensor (119) and decoding the signal and determining the distance of the boundary sensor (119) to the boundary wire (103, 104).