Robotic Navigation Sensor Calibration for Signal Blockage
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Solution Overview
Problem
Robotic work tools face challenges in navigating complex areas due to unreliable satellite navigation signals, which can be blocked by structures and foliage, leading to inaccurate positioning and incomplete coverage of work areas.
Innovation Solution
A robotic lawnmower system equipped with a position determining device and deduced reckoning navigation sensors that switch to alternative navigation when GNSS signals are unreliable, allowing for calibration of navigation errors and correction of position and direction, enabling continued operation and execution of complex patterns even in signal-blocked areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite navigation (GNSS) is used for positioning the robotic work tool, then global coverage and autonomous positioning capability are improved, but signal reliability deteriorates when signals are blocked by buildings, roofs, awnings, foliage or trees
Solution Approach 1:
The patent introduces a beacon as an intermediary positioning system that operates in conjunction with GNSS. When GNSS signals are blocked, the robotic work tool uses signals from beacons placed in the work area to determine its position. This intermediary system bridges the gap created by signal blockage, maintaining positioning reliability without requiring direct line-of-sight to satellites.
Solution Approach 2:
The system performs preliminary calibration of deduced reckoning sensors during periods when GNSS signals are available and reliable. This calibration data is stored and later applied when GNSS signals become unavailable, allowing the system to maintain accurate positioning and navigation even during signal blockage periods.
2Measurement precision
If differential GNSS with beacons is used to improve positioning accuracy, then measurement precision is improved, but the system complexity increases due to additional infrastructure requirements
Solution Approach 1:
The navigation system dynamically switches between different positioning methods based on signal availability. The controller monitors GNSS signal quality and automatically transitions between GNSS-only mode, beacon-assisted mode, and deduced reckoning mode. This dynamic adaptation allows the system to maintain high positioning accuracy without requiring complex infrastructure to be constantly active, reducing overall system complexity.
Solution Approach 2:
The robotic work tool is equipped with multiple positioning capabilities (GNSS receiver, beacon receiver, and deduced reckoning sensors) that can serve multiple functions. The same sensor suite used for primary navigation also provides backup positioning and calibration data, eliminating the need for separate specialized systems and reducing overall complexity.
3Duration of action of moving object
If deduced reckoning navigation is used as alternative when GNSS is unavailable, then operational continuity is improved, but navigation accuracy deteriorates due to accumulation of errors over time
Solution Approach 1:
The system performs preliminary calibration of deduced reckoning sensors during periods when GNSS signals are available and reliable. This calibration establishes accurate baseline parameters for the sensors. When GNSS signals become unavailable and the system switches to deduced reckoning, these pre-calibrated parameters are used, significantly reducing error accumulation and maintaining navigation accuracy over extended periods without GNSS coverage.
Solution Approach 2:
The system continuously monitors the quality and availability of GNSS signals and provides feedback to the controller. When GNSS signals become unavailable, this feedback triggers a switch to deduced reckoning mode. When GNSS signals become available again, the system uses the known accurate GNSS position to detect and correct any drift that has accumulated in the deduced reckoning system, thereby maintaining long-term navigation accuracy.
Data Source
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AI summary
A robotic work tool system (200) comprising a charging station (210) and a robotic work tool (100), said robotic work tool (100) comprising a position determining device (190) for determining a current position and at least one deduced reckoning navigation sensor (195), the robotic work tool (100) being configured to determine that a reliable current position is possible to determine and in response thereto calibrate at least one of the at least one deduced reckoning navigation sensor (195).