Method for detecting a measurement error in a robotic cleaning device
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Solution Overview
Problem
Robotic vacuum cleaners face inaccuracies in obstacle detection due to changes in the structured light source's angle and baseline over time, caused by factors like temperature changes and vibrations, leading to measurement errors that require recalibration.
Innovation Solution
The robotic cleaning device autonomously detects measurement errors by estimating distances to landmarks using structured light and dead reckoning, allowing for calibration of parameters in the distance calculating algorithm, such as the angle and baseline, to ensure accurate navigation and cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the structured light source and camera are fixed at predetermined positions, then the device complexity is reduced, but measurement precision deteriorates over time due to parameter changes
Solution Approach 1:
The system performs preliminary calibration by moving to a known landmark position and comparing the measured distance with the expected distance from dead reckoning. This preliminary action detects parameter deviations before they cause significant navigation errors, allowing for preventive recalibration of the structured light source angle or baseline parameters.
Solution Approach 2:
The system establishes a feedback loop where distance measurements from the structured light camera are continuously compared with dead reckoning positions. When a discrepancy exceeds a threshold, the system triggers parameter recalibration. This feedback mechanism maintains measurement precision without requiring complex real-time adjustment mechanisms.
2Manufacturing precision
If factory calibration is performed for each device, then manufacturing precision is improved, but ease of manufacture deteriorates due to additional testing requirements
Solution Approach 1:
The robotic cleaning device performs self-calibration autonomously during normal operation by navigating to known landmarks and detecting measurement errors. This eliminates the need for manual factory calibration testing, reducing manufacturing complexity while maintaining accuracy. The device serves its own calibration needs using its existing navigation and measurement systems.
3Measurement precision
If parameter recalibration is performed frequently, then measurement precision is maintained, but loss of time increases due to calibration interruptions
Solution Approach 1:
The system uses feedback from dead reckoning position comparisons to detect when calibration is actually needed, triggering recalibration only when measurement errors exceed a threshold. This prevents unnecessary frequent calibrations while maintaining precision when needed.
Solution Approach 2:
Instead of performing full recalibration routines frequently, the system performs partial calibration only when necessary, using the existing landmark detection and dead reckoning infrastructure. This minimizes calibration time while maintaining sufficient precision for navigation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables continuous accurate measurement over a long period without the need for external calibration, enhancing the device's autonomy and user-friendliness by detecting and adjusting for consistent measurement errors, thus improving navigation and cleaning performance.
Implementation Method 1
estimating a distance to the landmark by illuminating the landmark with structured light and extracting information from the reflections of the structured light
Implementation Method 2
drive means in the form of one or more motors for moving the cleaner across a surface
Data Source
AI summary
A robotic cleaning device having a main body, a propulsion system, a contact detecting portion connected to the main body, a dead reckoning sensor operatively connected to the propulsion system and an obstacle detecting device comprising a camera and a first structured light source arranged at a distance from each other on the main body. The robotic cleaning device may further include a processing unit arranged to control the propulsion system. The obstacle detecting device and the processing unit are arranged to estimate a distance to the landmark and to subsequently move the robotic cleaning device into contact with the landmark while measuring an actual distance to the landmark, whereby the actual distance is then compared with the estimated distance to determine a measurement error.