Foot Velocity Estimation Using Particle Filter and Pressure Sensor
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Solution Overview
Problem
Existing methods for estimating foot velocity using footwear-mounted sensors are limited by the need for assumptions about walking style and terrain, leading to inaccuracies, especially in varied conditions and with gait disorders, and are prone to drift errors.
Innovation Solution
Incorporating an inertial measurement unit, pressure sensor, and data processing unit configured with a particle filter that estimates foot velocity by combining angular velocity and distance from the center of pressure, allowing for accurate gait data estimation in real-life conditions without relying on specific assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accelerometry technique with inertial measurement unit is used to estimate foot velocity, then velocity estimation can be obtained, but measurement precision deteriorates due to gravitational component correction requirements and drift errors
Solution Approach 1:
The patent introduces a pressure sensor as an intermediary measurement device that directly measures the vertical force component during foot-ground contact. This pressure measurement serves as a mediator to correct the velocity estimation obtained from IMU data, compensating for gravitational effects and drift errors without requiring complex correction algorithms.
Solution Approach 2:
The patent implements a feedback mechanism where the pressure sensor measurements are continuously used to correct and refine the velocity estimation from the IMU. The pressure data provides real-time feedback about the actual contact forces, allowing the system to adjust and compensate for errors in the IMU-based velocity calculation throughout the gait cycle.
2Measurement precision
If assumptions about consistent walking style and terrain are made for accurate velocity estimation, then measurement precision improves, but adaptability deteriorates when subject alternates between walking and running or moves over varied terrain
Solution Approach 1:
The patent changes the fundamental parameters used for velocity estimation by incorporating pressure sensor measurements that directly reflect actual contact forces. Instead of relying on fixed assumptions about gait patterns, the system adapts to varying conditions by using real-time pressure data to characterize the actual contact mechanics, whether during walking, running, or transition phases.
Solution Approach 2:
The patent creates a universal velocity estimation method that works across multiple gait conditions (walking, running, varied terrain) by using the pressure sensor to detect and characterize the specific contact patterns of each condition. The same measurement system adapts its interpretation based on the detected gait phase, eliminating the need for separate assumptions for each activity type.
3Productivity
If inertial measurement unit data is integrated to obtain velocity, then velocity estimation can be performed, but device complexity increases due to required correction steps for gravitational component and initial conditions
Solution Approach 1:
The patent extracts the velocity estimation function from the complex IMU data processing chain and creates a separate, simpler correction mechanism using pressure sensor data. Instead of trying to correct all IMU errors through complex algorithms, the system isolates the velocity estimation and uses pressure measurements to provide direct correction for the most significant error sources (gravitational and drift components).
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
The solution provides accurate and generalized foot velocity estimation, reducing errors and improving accuracy across different terrains and gait phases, including those with gait disorders, by using a particle filter to correct and refine IMU velocity measurements.
Implementation Method 1
Inertial measurement units can be used to estimate the foot velocity via the accelerometry technique, in which foot velocity is estimated by integration of the acceleration recorded by the accelerometer of the inertial measurement unit
Implementation Method 2
the orientation calculated by the integration of the angular velocity recorded by the gyroscope of the inertial measurement unit
Implementation Method 3
a pressure sensor; and a data processing unit obtaining and estimating gait data based on measurements of the inertial measurement unit and the pressure sensor
Implementation Method 4
the data processing unit being configured to estimate the gait data by applying a particle filter
Data Source
AI summary
Footwear including an inertial measurement unit (IMU); a pressure sensor (PS); and a data processing unit configured to estimate gait data by applying a particle filter. A method of processing the gait data in the footwear, and a computer program to, when the program is executed by a computer, cause the computer to carry out the method.