Foot-Mounted Sensor Fusion for Stride Length Measurement
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Solution Overview
Problem
Existing techniques for measuring foot orientation and position during the swing phase of gait primarily focus on medial-lateral and cranial-caudal movements, failing to accurately determine stride length and direction without requiring additional sensors or known leg lengths.
Innovation Solution
A tri-axial accelerometer, gyroscope, and magnetometer sensor configuration is used to capture kinematic data, establishing a global spatial reference system that allows for the determination of step length and width without additional sensors, using a wireless network to transmit data and calculate gait parameters relative to a fixed coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tri-axial accelerometer and gyroscope IMU are placed on the foot to measure foot orientation and position, then foot movement in medial-lateral and cranial-caudal direction can be measured, but stride length and direction cannot be accurately determined
Solution Approach 1:
The patent combines tri-axial accelerometer, gyroscope, and magnetometer sensors into an integrated sensor unit that captures both foot orientation data and positional information. This merging of sensor types enables simultaneous measurement of foot movement in multiple directions while also determining stride length and direction, resolving the information loss problem.
Solution Approach 2:
The patent extends measurement from two dimensions (medial-lateral and cranial-caudal) to three dimensions by incorporating magnetometer data and establishing a global coordinate system. This dimensional expansion enables accurate determination of stride length and direction by capturing movement in the anterior-posterior direction as well.
2Measurement precision
If tri-axial gyroscope, accelerometer and magnetometer sensor configuration is used to measure stride length, then stride length can be measured, but the length of both upper leg and lower leg must be known
Solution Approach 1:
The sensor unit on the foot independently determines stride length by processing its own accelerometer, gyroscope, and magnetometer data through integration and coordinate transformation. The system uses only the foot-mounted sensor's measurements and does not require external input of leg length parameters, making the measurement self-sufficient.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical sensors on different body segments (requiring known leg lengths) with a computational approach using a single multi-functional sensor unit. By substituting mechanical measurement with sensor fusion and mathematical integration, the system eliminates the need for additional sensor information.
3Measurement precision
If additional sensors are placed on the leg and thigh to measure stride length, then stride length can be measured, but device complexity increases
Solution Approach 1:
The foot-mounted sensor unit performs multiple functions: measuring foot orientation, position, acceleration, angular velocity, and determining stride length and direction. This multi-functional sensor replaces what would otherwise require multiple separate sensors distributed across the foot, leg, and thigh, significantly reducing overall device complexity.
Solution Approach 2:
The patent extracts the stride length measurement capability from the multi-sensor system and concentrates it in a single foot-mounted unit. By taking out the essential measurement function and locating it at one strategic position, the system eliminates the need for additional sensors on the leg and thigh while maintaining measurement accuracy.
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 measurement of stride length and width, along with speed and velocity, without the need for additional sensors, allowing for effective monitoring of gait parameters and health conditions.
Implementation Method 1
A tri-axial accelerometer, gyroscope, and magnetometer sensor configuration is used to capture kinematic data
Implementation Method 2
A tri-axial accelerometer, gyroscope, and magnetometer sensor configuration is used to capture kinematic data
Implementation Method 3
A tri-axial accelerometer, gyroscope, and magnetometer sensor configuration is used to capture kinematic data
Data Source
AI summary
Briefly, in accordance with one or more embodiments, a kinematic sensor may be carried by or on one or more body segments of a user to obtain one or more kinematic variables based at least in part on movement of the user with respect to a fixed, global reference system. The kinematic sensor comprises a tri-axial accelerometer sensor, a gyroscope sensor, and a magnetometer sensor to define the global reference system and to obtain kinematic data. The kinematic data may be transmitted via a wireless link to a remote information handling system or device, for example to monitor a health status of the user based at least in part on movement of the user with respect to the fixed, global reference system.