Robotic Work Tool Navigation with Dead Reckoning Error Correction
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Solution Overview
Problem
Robotic work tools face challenges in navigating complex areas due to unreliable satellite navigation signals, which can result in incomplete coverage and uneven operation, especially when signals are blocked by obstacles like buildings or foliage.
Innovation Solution
The robotic work tool employs a position determining device and deduced reckoning navigation sensors to determine navigation errors, allowing it to adjust its trajectory and align with expected positions and directions, ensuring reliable operation even in areas with unreliable signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite navigation signals are used for navigation, then global coverage and position determination capability are improved, but signal reliability deteriorates when blocked by buildings, foliage or other obstacles
Solution Approach 1:
The system continuously monitors the reliability of position determination and uses this feedback to switch between navigation modes. When GNSS reliability is insufficient, the system transitions to dead reckoning navigation, and when GNSS reliability is sufficient, it switches back to GNSS navigation, ensuring continuous reliable operation
Solution Approach 2:
The system changes the navigation mode parameter based on signal reliability conditions. It dynamically adjusts between two navigation modes (GNSS and dead reckoning) by monitoring signal quality parameters, thereby adapting to varying environmental conditions and maintaining navigation reliability
2Reliability
If the robotic work tool switches to dead reckoning navigation when GNSS signals are unreliable, then navigation continuity is improved, but navigation accuracy deteriorates due to accumulated errors
Solution Approach 1:
The system performs preliminary action by recording the last known accurate position and trajectory information before switching to dead reckoning navigation. This stored reference information is used to correct accumulated errors and recalibrate the navigation system when GNSS signals are restored
Solution Approach 2:
The system uses feedback by comparing the current dead reckoning position with the expected position based on recorded trajectory data. When GNSS signals are restored, the system uses the feedback from position comparison to correct navigation errors and realign the trajectory
3Productivity
If the robotic work tool maintains trajectory based on last known position during signal loss, then operation continuity is improved, but coverage completeness deteriorates due to position drift
Solution Approach 1:
The system continuously monitors navigation error through feedback mechanisms and uses this information to adjust the trajectory. When position drift is detected upon signal restoration, the system calculates correction vectors to realign with the expected trajectory, ensuring complete coverage
Solution Approach 2:
The system performs preliminary action by pre-calculating and recording the expected trajectory and coverage areas before signal loss occurs. This pre-planned trajectory information serves as a reference for correcting position drift and ensuring complete area coverage when navigation is restored
Data Source
AI summary
A robotic work tool system, comprising a robotic work tool, said robotic work tool comprising a position determining device for determining a current position and at least one deduced reckoning (also known as dead reckoning) navigation sensor, the robotic work tool being configured to determine that a reliable and accurate current position is possible to determine and in response thereto determine an expected navigation parameter, compare the expected navigation parameter to a current navigation parameter to determine a navigation error, determine if the navigation error is negligible, and if the navigation error is not negligible, cause the robotic work tool to change its trajectory to accommodate for the navigation error. Wherein the robotic work tool (100) is further configured to change the trajectory by aligning the trajectory with an expected trajectory, wherein the expected trajectory is determined as an expected direction originating from an expected position and wherein the robotic work tool (100) is configured to change the trajectory by returning to a position that should have been visited and aligning the trajectory with the expected direction originating from the expected position, said position that should have been visited being aligned with the expected direction originating from the expected position.