Travel Direction Estimation Using Sensor Fusion and Phase Analysis
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Solution Overview
Problem
Accurately estimating the travel direction of a moving body when a self-contained sensing device is held by a person whose posture and arm position change, as the device's positional relationship with the body is variable.
Innovation Solution
A device and method that include acceleration and angular velocity measuring sections, gravitational direction vector estimation, tentative travel direction vector generation, walk frequency calculation, and a computing section to determine the travel direction vector by projecting components and calculating power values and phase differences to select the optimal travel direction vector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a self-contained sensing device is held by a moving body with variable posture and position, then the device can be easily operated and carried, but the travel direction estimation accuracy deteriorates due to changing positional relationships
Solution Approach 1:
The patent applies parameter changes by transforming the estimation approach from fixed-coordinate assumptions to dynamic parameter adaptation. The system continuously adjusts the gravitational direction vector and travel direction vector based on real-time acceleration and angular velocity data, allowing accurate estimation despite variable device posture and position. This resolves the contradiction by making the estimation parameters adaptive rather than static.
Solution Approach 2:
The patent implements dynamics by using continuous tracking of gravitational direction and horizontal reference directions through fusion of acceleration sensor, angular velocity sensor, and magnetic sensor data. The system dynamically updates vectors including the gravitational direction vector, first horizontal reference direction vector, and second horizontal reference direction vector to maintain accuracy despite device movement and posture changes.
2Measurement precision
If multiple sensing devices are fixed to the moving body, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies universality by making a single terminal device perform multiple sensing functions. The terminal device integrates acceleration sensing, angular velocity sensing, and magnetic field sensing capabilities within one unit held by the user. This multi-functional approach achieves accurate travel direction estimation without requiring multiple separate fixed sensors on the body, thus resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent merges multiple sensing functions into a single terminal device. By combining acceleration sensor data, angular velocity sensor data, and magnetic sensor data from one integrated device, the system achieves comprehensive motion tracking and direction estimation without the complexity of multiple separate sensing systems distributed on the body.
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 estimation of travel direction even when the sensing device's position and posture change, effectively handling variable relationships with the moving body.
Implementation Method 1
tracking a gravitational orientation vector on the basis of data outputted by an acceleration sensor, an angular velocity sensor, and a magnetic sensor
Implementation Method 2
tracking a gravitational orientation vector on the basis of data outputted by an acceleration sensor, an angular velocity sensor, and a magnetic sensor
Implementation Method 3
tracking a gravitational orientation vector on the basis of data outputted by an acceleration sensor, an angular velocity sensor, and a magnetic sensor
Data Source
AI summary
The present invention provides a device and method for estimating a travel direction of a moving body, the device and method allowing highly accurate estimation of the travel direction even in the case where the positional relationship between the moving body and the self-contained sensing device or the posture is changed freely.The travel direction estimating device includes (i) a gravitational direction vector estimating section 2407 for estimating a gravitational direction vector on the basis of respective outputs of an acceleration sensor and an angular velocity sensor, (ii) a tentative travel direction vector generating section 2413 as a candidate of travel direction vector, (iii) a walk frequency estimating section 2424 for estimating a walk frequency from component data resulting from projecting acceleration component data for the gravitational direction vector, and (iv) a travel direction vector determining section 2425 for determining an objective function and a phase difference on the basis of a frequency component of a component Af resulting from projecting the acceleration component data for a travel direction vector, a frequency component of a component An resulting from projecting the acceleration component data for a side-to-side direction vector, a frequency component of a component Ws resulting from projecting angular velocity component data for the travel direction vector, a frequency component of a component Wn resulting from projecting the angular velocity component data for the side-to-side direction vector, a walk frequency, and the phase of the walk frequency, selecting as travel direction vectors, tentative travel direction vectors with which the phase difference is within a predetermined range and each of which maximizes the value of the objective function, and determining the side of the travel direction.