Motion Sensor Trajectory Orientation Estimation
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Solution Overview
Problem
Existing methods for estimating the trajectory orientation of a wearer using a motion sensor are inadequate, particularly when the sensor is integrated into portable devices like mobile phones or tablets, as they rely on restrictive hypotheses and are not robust due to parasitic movements and the need for extensive measurement recording, leading to non-real-time estimates.
Innovation Solution
A method that determines the orientation of the motion sensor relative to the trajectory by detecting phases of disorientation and updating the orientation using the last known value, assuming constant orientation during disorientation phases, and utilizing a combination of accelerometers, magnetometers, and gyrometers for estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor is attached to the wearer with binding assumptions about relative orientation, then the orientation estimation becomes simpler, but the adaptability to different wearing conditions deteriorates
Solution Approach 1:
The patent implements dynamic adaptation of the orientation estimation approach based on detected disorientation phases. The system transitions between different estimation modes (during disorientation vs. after reorientation) to maintain accuracy across varying wearing conditions without requiring fixed binding assumptions about sensor placement.
2Device complexity
If horizontal acceleration is used to estimate trajectory orientation, then the measurement process is simplified, but the reliability deteriorates due to parasitic movements
Solution Approach 1:
The patent introduces an intermediary detection mechanism that identifies disorientation phases through analysis of movement patterns. This intermediary step allows the system to recognize when parasitic movements are present and adjust the estimation approach accordingly, rather than directly relying on horizontal acceleration during all phases.
Solution Approach 2:
The system implements feedback through continuous monitoring of sensor data to detect disorientation phases. This feedback loop enables the system to adapt its estimation strategy in real-time, improving reliability by avoiding direct horizontal acceleration-based estimation during periods when parasitic movements are detected.
3Measurement precision
If multiple measurements are recorded prior to calculation, then the estimation accuracy improves, but the response time deteriorates
Solution Approach 1:
The patent dynamically adjusts the measurement window and processing intensity based on detected disorientation phases. During disorientation phases, the system uses minimal processing with shorter measurement windows to maintain real-time response. After reorientation is detected, the system can afford to process more measurements for improved accuracy, thus adapting the precision-time tradeoff to current conditions.
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 approach provides a more robust and real-time estimation of trajectory orientation by simplifying the estimation process during disorientation phases and reducing the impact of parasitic movements, enabling accurate tracking of trajectory orientation without relying on restrictive assumptions.
Implementation Method 1
The movement sensor comprises an accelerometer with three measurement axes
Implementation Method 2
The movement sensor comprises a magnetometer with three measurement axes
Implementation Method 3
The movement sensor comprises a gyrometer with three measurement axes
Data Source
Figure 1~2
Figure 3~4
AI summary
This method for estimating a trajectory orientation followed by a carrier of a movement sensor (22) comprises the following steps: determining (100) an orientation of the movement sensor (22) relative to the trajectory; estimating (102) an orientation of the movement sensor (22) relative to a fixed coordinate system; estimating (104) an orientation of the trajectory relative to the fixed coordinate system by way of the orientation determined for the movement sensor (22) relative to the trajectory and of the orientation estimated for the movement sensor (22) relative to the fixed coordinate system. It furthermore comprises the following steps: detecting (110) a start and an end of a phase of misorientation of the movement sensor (22) relative to the trajectory; updating (112), after the detected end of the misorientation phase, the orientation of the movement sensor (22) determined relative to the trajectory by way of the orientation of the trajectory relative to the fixed coordinate system such as estimated at the detected start of the misorientation phase and of the orientation of the movement sensor(22) relative to the fixed coordinate system such as estimated after the detected end of the misorientation phase.