Mobile Device Magnetic Sensor Calibration via Posture Detection
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Solution Overview
Problem
Existing mobile devices require users to perform specific actions for accurate magnetic sensor calibration, which may not guarantee sufficient accuracy without intentional posture changes, leading to potential inaccuracies in geomagnetism direction detection.
Innovation Solution
A mobile device with a magnetic sensor and a posture detection sensor, such as a gyroscope, acquires sampling data in various states to calculate offset values independently, allowing for precise calibration without user intervention by determining changes in posture naturally during device usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration processing is carried out by prompting a user to perform a special action of rotating the mobile device, then the offset value can be calculated using maximum and minimum output values, but the user convenience deteriorates due to requiring intentional user actions
Solution Approach 1:
The system performs calibration automatically using posture detection sensor data to identify when the device has naturally changed orientation. The processor monitors posture changes and selectively accumulates magnetic sensor outputs without requiring user initiation, making the calibration process self-service and transparent to the user while maintaining accuracy through posture-verified sampling
Solution Approach 2:
The patent replaces the mechanical interaction of manual device rotation with an automated detection system. The posture detection sensor electronically monitors device orientation and triggers calibration based on detected posture changes, substituting the mechanical user action with an automated sensing and processing system that achieves the same calibration goal without physical user involvement
2Ease of operation
If calibration is performed without user action by simply sampling magnetic sensor outputs, then user convenience is improved, but the offset value accuracy deteriorates because sufficient posture changes may not occur
Solution Approach 1:
The system continuously monitors posture detection sensor outputs and uses this feedback to determine when to accumulate magnetic sensor data. The processor checks whether posture changes have occurred and selectively accumulates samples only when appropriate orientation changes are detected, ensuring calibration accuracy while maintaining automated operation without user intervention
Solution Approach 2:
The calibration process dynamically adjusts its sampling behavior based on real-time posture detection. Rather than uniform sampling, the system adapts its data accumulation to actual device usage patterns, activating calibration sampling only when posture changes indicate meaningful orientation transitions, thus ensuring accuracy while operating automatically
3Reliability
If multiple sampling data items are acquired in different device directions, then the reliability of offset value calculation is improved, but the time required for calibration increases
Solution Approach 1:
The system performs calibration sampling periodically based on detected posture changes rather than continuously or at fixed time intervals. Each time the posture detection sensor registers a meaningful orientation change, the system accumulates magnetic sensor data, creating a periodic sampling pattern that naturally captures diverse device orientations over time without requiring dedicated calibration sessions
Solution Approach 2:
The calibration process operates continuously in the background by monitoring posture changes during normal device usage. Rather than requiring a separate, time-consuming calibration session, the system continuously accumulates magnetic sensor data whenever posture changes occur, integrating calibration into the device's normal operation and eliminating dedicated calibration time
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 precise calculation and updating of offset values, improving the accuracy of geomagnetism direction detection and reducing the need for user-initiated calibration actions, ensuring reliable geomagnetism identification even in varying magnetic environments.
Implementation Method 1
A magnetic sensor is used for detecting the direction (azimuth) of a mobile device. The direction of the mobile device incorporating the magnetic sensor can be identified based on the direction of the geomagnetism detected by the magnetic sensor.
Implementation Method 2
a posture detection sensor for detecting a posture of the mobile device independently of the magnetic sensor
Data Source
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AI summary
A mobile device includes a magnetic sensor and a posture detection sensor for detecting a posture of the mobile device independently of the magnetic sensor, which acquires output data of the magnetic sensor as a plurality of sampling data items in a plurality of states in which the posture detection sensor determines that the mobile device is directed in directions different from one another, the plurality of sampling data items respectively corresponding to the plurality of states, and calculates an offset value which is estimated to be output by the magnetic sensor when the magnetic sensor is not sensing geomagnetism based on the acquired plurality of sampling data items.