Robotic Work Tool Pose Correction for Direction Sensor Drift
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Solution Overview
Problem
Existing robotic work tools, such as lawnmowers, face inaccuracies in determining position due to errors in direction sensors like gyros, which increase over time, leading to navigation drift and potential operational issues.
Innovation Solution
A method for robotic work tools that includes calibrating direction sensors, determining errors, and interpolating these errors linearly to correct positions, using deduced reckoning and environmental factors to maintain accurate navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If deduced reckoning with direction sensors is used for navigation, then the robotic work tool can determine position without satellite signals, but the position accuracy deteriorates over time due to sensor drift
Solution Approach 1:
The system performs preliminary calibration of the direction sensor at the beginning of operation or at predetermined intervals. This preliminary action establishes a reference state for the sensor, allowing subsequent drift to be detected and corrected by comparing against this initial calibrated state, thereby maintaining position accuracy over time
Solution Approach 2:
The system continuously monitors the direction sensor output and compares it against expected values based on the robotic work tool's motion model and odometry data. When drift is detected through this feedback mechanism, the system retroactively corrects position calculations to compensate for the accumulated error
2Measurement precision
If calibration of direction sensors is performed frequently to maintain accuracy, then position determination improves, but operational time is lost due to calibration interruptions
Solution Approach 1:
The system performs comprehensive sensor calibration preliminarily at the start of operation or at predetermined intervals rather than continuously during operation. This preliminary calibration establishes a reference state that can be used for extended periods, minimizing interruptions while maintaining accuracy
Solution Approach 2:
The system performs calibration only when necessary based on operational context, such as at the beginning of a work cycle or when entering new operational areas. This partial calibration approach applies the corrective action only where and when needed, rather than continuously throughout all operations
3Measurement precision
If retroactive correction of sensor errors is implemented, then navigation accuracy improves, but computational complexity increases
Solution Approach 1:
The system introduces an intermediary computational layer that processes sensor data through a defined correction algorithm. This intermediary processing step applies retroactive correction by calculating the difference between expected and actual sensor readings, then adjusting position calculations accordingly, making the complex correction process systematic and manageable
Data Source
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AI summary
A method for use in a robotic work tool system comprising a robotic work tool 100, the robotic work tool comprising a controller 110, a deduced reckoning sensor 180 comprising a direction sensor 181, and wherein the method comprises: receiving sensor input from the deduced reckoning sensors 180, determining a current sensed position of the robotic work tool 100 based on the received sensor input and a previous position of the robotic work tool 100, calibrating the direction sensor, determining an error in sensor input, interpolating the error in sensor input to the previous position, and determining a corrected position of the robotic work tool 100 based on the received sensor input, the interpolated error and the previous position of the robotic work tool 100.