Upper Body Motion Measurement Using Multi-Sensor Inertia Arrays
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Solution Overview
Problem
Existing methods for measuring the change in upper body posture during walking, such as using angular velocity sensors, are hindered by discomfort and inaccurate measurements due to the large contact surface area and noise in detection values, leading to unreliable assessment of walking state and angular acceleration.
Innovation Solution
A system comprising multiple inertia sensor units with both angular velocity and acceleration sensors attached to different locations on the upper body, which estimate the attitude and acceleration in a global coordinate system, allowing for accurate measurement of angular acceleration by linearly combining acceleration values from multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an angular velocity sensor is attached to the upper body through a fixing plate with large contact surface, then the measurement reliability is improved, but the subject experiences discomfort and the walking form is altered
Solution Approach 1:
The invention divides the upper body into multiple measurement locations (chest, abdomen, waist, etc.) and attaches angular velocity sensors at each location. This segmentation allows the system to collect comprehensive posture data while using smaller, less intrusive sensors at each location compared to a single large fixing plate, thereby reducing discomfort while maintaining measurement reliability.
Solution Approach 2:
The invention transitions from a single-point measurement approach to a multi-point spatial distribution approach. By placing sensors at multiple locations along the vertical dimension of the upper body, the system achieves more reliable posture measurement through spatial redundancy while each individual sensor maintains a small contact area, avoiding the discomfort associated with large fixing plates.
2Object-affected harmful factors
If the contact area of the angular velocity sensor is minimized to avoid discomfort, then the subject comfort is improved, but the measurement accuracy of upper body posture changes deteriorates
Solution Approach 1:
The invention segments the measurement task across multiple small sensors distributed at different locations on the upper body. Each sensor has a minimal contact area for comfort, but collectively they provide comprehensive and accurate posture information by capturing angular velocities at multiple points, which compensates for the small individual sensor size.
Solution Approach 2:
The invention combines data from multiple angular velocity sensors placed at different locations on the upper body to achieve accurate posture measurement. By merging the information from these distributed small sensors, the system attains measurement accuracy comparable to or better than a single large sensor, while maintaining subject comfort.
3Measurement precision
If angular acceleration is calculated by differentiating angular velocity detection values, then the angular acceleration measurement is obtained, but the noise components cause deteriorated measurement accuracy
Solution Approach 1:
The invention segments the angular acceleration measurement task into multiple parallel calculations from different sensor locations. By calculating angular acceleration from angular velocity at multiple positions simultaneously, the system can use averaging or other combination techniques to reduce the impact of noise differentiation, thereby improving measurement accuracy while obtaining angular acceleration data.
Solution Approach 2:
The invention implements a feedback mechanism where angular velocity data from multiple sensors are continuously monitored and combined. This allows for noise filtering and validation before differentiation, improving the quality of angular acceleration measurements by using feedback from redundant measurement channels to compensate for noise amplification effects.
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 enables reliable measurement of upper body posture changes with minimal discomfort and improved accuracy by closely following the actual angular acceleration, even when attached to the body without altering the normal walking form.
Implementation Method 1
an angular velocity sensor that detects an angular velocity
Implementation Method 2
an acceleration sensor that detects an acceleration
Data Source
AI summary
An upper body motion measurement system1 has a plurality of inertia sensor units 2, each of which incorporating an angular velocity sensor 4 and an acceleration sensor 5. The plurality of the inertia sensor units 2 is attached to places that are different from each other on the upper body of a subject P. Based on the detection outputs of the angular velocity sensor 4 and the acceleration sensor 5, the attitude of each of the inertia sensor units 2 is estimated, and the acceleration thereof is further estimated. The angular acceleration of the upper body of the subject P is estimated based on the estimated accelerations of the plurality of the inertia sensor units 2.