Robotic Work Tool Positioning with Feature-Based GNSS Fallback
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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 navigation and safety within operational areas.
Innovation Solution
A robotic work tool system equipped with a satellite navigation sensor and additional navigation sensors, including distance sensors and deduced reckoning sensors, uses a stored map of the operational area to determine its position by identifying matching features and calculating distances, ensuring accurate navigation even when satellite positioning is unreliable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite navigation is used for position determination, then navigation functionality is enabled, but position accuracy deteriorates when satellite reception is unreliable
Solution Approach 1:
The patent combines satellite navigation sensor with additional navigation sensors (distance sensors, deduced reckoning sensors) to create a hybrid navigation system. When satellite navigation is unreliable, the system merges data from multiple alternative sensors to determine position, thereby maintaining both reliability and accuracy that neither system could achieve alone.
Solution Approach 2:
The patent introduces an intermediary system (sensor-based navigation using distance sensors and feature matching) that mediates between unreliable satellite navigation and the need for accurate position determination. This intermediary approach provides a fallback mechanism that maintains position accuracy when satellite reception fails.
2Reliability
If sensor-based navigation is used as alternative to satellite navigation, then navigation functionality is maintained, but position accuracy deteriorates
Solution Approach 1:
The patent merges multiple sensor types (distance sensors for measuring distances to features, deduced reckoning sensors for tracking movement) with the stored map data to create a composite navigation solution. This combination compensates for the individual limitations of each sensor type and achieves accurate position determination without satellite navigation.
Solution Approach 2:
The patent transitions from relying solely on satellite-based global positioning to using local environmental features (trees, flowerbeds, buildings) as reference points. This dimensional shift from space-based to ground-based navigation creates an alternative positioning dimension that is independent of satellite reception quality.
3Reliability
If multiple navigation sensors are integrated, then navigation reliability improves, but device complexity increases
Solution Approach 1:
The patent implements a dynamic sensor system that adapts its complexity based on operational needs. The controller selectively activates and switches between different navigation sensors based on satellite reception quality and operational context, maintaining reliability while minimizing unnecessary complexity in normal conditions.
Solution Approach 2:
The patent designs the navigation system with multi-functional sensors that serve multiple purposes. The distance sensors and deduced reckoning sensors are used both for position determination and for other operational functions, reducing overall system complexity while maintaining navigation reliability.
Data Source
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Figure 3
Figure 4A~4B
AI summary
A robotic work tool system (200) comprising a robotic work tool (100) arranged to operate in an operational area (205), and the robotic work tool (100) comprising a controller (110), a memory (120), a satellite navigation sensor (175) and one or more additional navigation sensors (180), and wherein the memory is configured to store a map of the operational are, said map application including a list of features, and wherein the controller (110) is configured to receive (510) sensor input from the satellite navigation sensor (175), the sensor input indicating a satellite position for the robotic work tool (100), determine (520) if the satellite position is a reliably determined, and if not so, determine a current position of the robotic work tool (100) by receiving sensor readings from the distance sensor (180), finding a matching feature in the list of features, the matching feature having a stored position, determine a distance to the feature and determining the current position based on the position of the matching feature and a distance to the feature.