Pool Cleaning Robot Navigation Without Factory Magnetometer Calibration
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Solution Overview
Problem
Pool cleaning robots (PCRs) face challenges in navigating pools without factory-calibrated magnetometers, as the magnetic fields in factories differ from those in pools, making calibration costly and inaccurate, and there is a need to direct PCRs to an exit position without relying on factory calibration.
Innovation Solution
A method involving a gyroscope and a detachable floating unit with a magnetometer for calibration, where the PCR aligns the gyroscope-based direction of movement estimate with the magnetometer-based direction, using a mapping process to determine the home direction for navigation, allowing for periodic alignment iterations to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a factory calibrated magnetometer is used for navigation, then the initial navigation accuracy is improved, but the cost increases and the calibration becomes inaccurate for pool environments
Solution Approach 1:
The patent extracts the magnetometer calibration process from the factory setting and relocates it to the pool environment. The magnetometer is calibrated in-situ within the pool using the pool's magnetic field characteristics, eliminating the need for factory calibration and making the calibration process specific to the actual operating environment.
Solution Approach 2:
The patent performs preliminary calibration actions by having the PCR execute specific movement patterns (figure-eight patterns, circular patterns) within the pool before actual navigation begins. This preliminary calibration establishes the relationship between magnetometer readings and actual directions in the specific pool environment, ensuring accurate navigation from the start.
2Adaptability or versatility
If traditional three-dimensional calibration is used, then comprehensive navigation coverage is improved, but the calibration complexity increases
Solution Approach 1:
The patent transitions from traditional three-dimensional calibration to a two-dimensional calibration approach suitable for pool surfaces. By recognizing that PCR navigation primarily occurs on the two-dimensional pool surface, the system simplifies the calibration process while maintaining adequate navigation coverage for pool cleaning operations.
Solution Approach 2:
The patent applies partial calibration action by focusing calibration efforts on the two-dimensional plane relevant to pool navigation rather than performing exhaustive three-dimensional calibration. The system executes specific movement patterns (figure-eight, circular) that provide sufficient calibration data for surface navigation without the complexity of full three-dimensional calibration.
3Measurement precision
If periodic alignment iterations are implemented, then navigation accuracy is maintained over time, but the computational processing increases
Solution Approach 1:
The patent implements periodic alignment iterations where the gyroscope and magnetometer are realigned at predetermined intervals during operation. This periodic recalibration maintains navigation accuracy over time by compensating for drift and environmental changes, while the predetermined timing optimizes the balance between accuracy maintenance and computational energy consumption.
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
Enables accurate navigation of PCRs within pools without factory calibration, ensuring efficient movement towards an exit point, even when the gyroscope accuracy falls, by using a two-dimensional calibration process that is simpler and less costly than traditional three-dimensional methods.
Implementation Method 1
A pool cleaning robot (PCR) may navigate within a pool using a magnetometer
Implementation Method 2
a gyroscope-based direction of movement estimate
Data Source
AI summary
A method for navigating a movable pool related platform (PRP), the method includes moving the movable PRP along a home direction, wherein the movable PRP is associated with a gyroscope and with a magnetometer, wherein the moving is based on a gyroscope-based direction of movement estimate, wherein the gyroscope was aligned with the magnetometer. The magnetometer was calibrated during a calibration process that includes (i) determining, by a controller of the movable PRP, a mapping between magnetometer readings and a magnetometer-based direction of movement estimate; wherein the mapping is based, at least in part, on a first range of the first axis magnetometer readings and a second range of the second axis magnetometer readings; and (ii) performing an alignment iteration that comprises aligning, by the controller, between the magnetometer-based direction of movement estimate and the gyroscope-based direction of movement estimate.