Autocorrelation Navigation for Autonomous Lawnmower Path Coverage

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing self-steering vehicles, such as autonomous lawnmowers, face challenges in reliably determining the contour of a work area and ensuring complete path coverage without redundant movements, especially in cost-sensitive private areas where precise navigation systems are not feasible.

Innovation Solution

The implementation of navigation means that process path section data with assigned orientation information, using autocorrelation analysis to determine if the vehicle has completely traveled the enclosing path, and a mapping unit to generate outline map data, allowing for efficient operation and error minimization through odometry and compass measurements, along with data compression techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional GPS or precise navigation systems are used, then position resolution and path coverage accuracy are improved, but device complexity and cost increase significantly

Engineering Contradiction:
Improveposition resolutionVSAvoidnavigation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic navigation systems (GPS, precise positioning) with a mechanical/algorithmic solution based on odometry (wheel encoder measurements) and autocorrelation analysis of perimeter wire signals. This substitution achieves sufficient position resolution for path coverage without the high cost and complexity of GPS systems, particularly suitable for private sector applications.

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

Solution Approach 2:

The patent creates a simplified copy of the perimeter wire contour by storing path section data (distance and orientation) during traversal. This copied path information is then used for autocorrelation analysis to detect complete coverage, eliminating the need for precise GPS positioning while maintaining adequate navigation accuracy.

Inventive Principle:
Principle #26Copying

2Device complexity

If simple block-length comparison is used for path recognition, then device complexity is reduced, but measurement precision and reliability of path completion detection deteriorate

Engineering Contradiction:
Improvenavigation system complexityVSAvoidpath completion detection accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent enhances path recognition by adding an orientation dimension to the simple block-length comparison. Instead of only comparing distance blocks, the system compares sequences of path sections with both distance and orientation information. This dimensional enhancement resolves ambiguities in simple contours (like rectangles) where identical block lengths appear multiple times, significantly improving path completion detection reliability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent performs preliminary autocorrelation analysis on stored path section data to identify characteristic sequences before attempting path completion detection. By pre-processing and storing orientation-corrected path sections, the system enables reliable recognition of complete contours even in simple geometries, avoiding false positives that would occur with simple block comparison alone.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If random navigation is used, then device complexity is minimized, but productivity and area coverage efficiency deteriorate due to redundant movements

Engineering Contradiction:
Improvecontrol system complexityVSAvoidarea coverage efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent implements feedback by continuously monitoring the sequence of path sections traversed and using autocorrelation analysis to detect when the complete contour has been covered. This feedback mechanism allows the system to transition from random navigation to informed navigation, stopping redundant movements once full coverage is achieved, thereby improving productivity without significantly increasing control system complexity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts navigation behavior based on detected path completion. The system transitions between random navigation mode (when coverage is incomplete) and termination mode (when complete coverage is detected), optimizing productivity at each stage while maintaining relatively simple control logic through the dynamic state changes.

Inventive Principle:
Principle #15Dynamics

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

This approach enables reliable and efficient path coverage with reduced error detection, allowing the vehicle to recognize completed routes and reorient itself effectively, even in the absence of precise navigation systems, thereby minimizing redundant movements and ensuring complete area coverage.

Implementation Method 1

Magnetic field sensors associated with the ARM are then able to detect whether the ARM is inside or outside the boundary defined by the wire by detecting the boundary wire signal

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP2452240B1Self-controlling vehicle
Publication Date: 2015.09.16 ROBERT BOSCH GMBH
  • EP2452240B1 patent drawingFigure 1~2
  • EP2452240B1 patent drawingFigure 3~4
  • EP2452240B1 patent drawing

AI summary

The invention relates to a self-controlling vehicle, designed for the autonomous movement in an area, comprising driving means (10) for movement and navigation means (12), wherein the navigation means are designed for the position determination along a closed path surrounding an operating space (34) of the area. According to the invention, the navigation means are designed for creating successive path sectional data, the path sectional data for route sections of the path has assigned orientation information, in particular angle information (f), and the navigation means are assigned with autocorrelation means (12), which are designed such that they determine from a sequence of path sectional data corresponding to a movement along the path by determining auto correlation data whether and/or that the vehicle has driven completely along the surrounding path and/or a sequence of route sections already driven is driven again.