Robotic Work Tool Positioning with Trusted Sensor Channel Switching

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Solution Overview

Problem

Existing robotic work tools, such as lawnmowers, face challenges in accurately determining their position when satellite navigation is unreliable, leading to inaccuracies in boundary adherence and operational patterns due to reliance on alternative navigation techniques that are not always precise.

Innovation Solution

A robotic work tool system equipped with an absolute position navigation sensor and additional sensors grouped in channels, where the controller determines the trustworthiness of the absolute position and selects the appropriate sensor channel for navigation based on priority, accuracy, and environmental factors, including fusion of multiple sensor positions for enhanced precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If satellite navigation is used for position determination, then navigation accuracy is improved, but reliability deteriorates when satellite reception is unavailable or untrusted

Engineering Contradiction:
Improveposition determination accuracyVSAvoidnavigation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent combines satellite navigation (absolute positioning) with sensor-based navigation (relative positioning) into a unified navigation system. The controller integrates data from both GPS receivers and sensors (odometers, accelerometers, gyroscopes, visual sensors) to determine position, allowing the system to switch between or combine these navigation methods based on their respective strengths and weaknesses.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system dynamically changes the weighting and trust level assigned to different navigation sources based on environmental conditions and signal quality. When satellite reception is untrusted, the controller increases reliance on sensor-based navigation parameters, effectively changing the navigation model from satellite-dependent to sensor-dependent.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If sensor-based navigation is used as alternative to satellite navigation, then reliability is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvenavigation reliabilityVSAvoidposition determination accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The controller acts as an intermediary that processes and fuses data from multiple navigation sources. It evaluates the quality and reliability of satellite signals versus sensor data, and intelligently combines them to produce a more accurate and reliable position estimate than either system could achieve alone.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The navigation system uses a composite approach by combining multiple navigation methodologies (satellite-based absolute positioning and sensor-based relative positioning) into a hybrid system that leverages the strengths of each component while mitigating their individual weaknesses.

Inventive Principle:
Principle #40Composite materials

3Reliability

If multiple navigation systems are integrated, then reliability and accuracy are improved, but device complexity increases

Engineering Contradiction:
Improvenavigation reliabilityVSAvoidnavigation system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The controller is designed as a multi-functional unit that can perform both satellite navigation processing and sensor-based navigation processing, as well as fuse these data sources. This universal controller reduces overall system complexity compared to having separate dedicated systems for each navigation method.

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

Solution Approach 2:

The navigation system dynamically adjusts its configuration and data fusion parameters based on real-time conditions. The controller can switch between different navigation modes (satellite-only, sensor-only, or fused) and adjust the weighting of different sensor inputs, making the system adaptable rather than statically complex.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4591695A1Improved determination of position for a robotic work tool
Publication Date: 2025.07.30 HUSQVARNA AB
  • EP4591695A1 patent drawingFigure 1~2
  • EP4591695A1 patent drawingFigure 3A~3B
  • EP4591695A1 patent drawingFigure 3C~4

AI summary

A method for a robotic work tool (100) arranged to operate in an operational area (205), and the robotic work tool (100) comprising a absolute position navigation sensor (175) and additional navigation sensors (180) grouped in one or more channels. The method comprises receiving (610) sensor input from the absolute position navigation sensor (175), the sensor input indicating a absolute position for the robotic work tool (100), determining (620) if the absolute position is a trusted position. If so, selecting (630) the absolute position as a position to be used for navigating the robotic work tool, and wherein the method further comprises receiving (615) sensor input from the one or more additional sensors (180) through the one or more channels. If the absolute position is not trusted, a position of selected channel(s) is selected (660) as the position to be used for navigation.