Inertial Measurement Unit for Free Flight Dynamics Analysis
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Solution Overview
Problem
Current methods for analyzing the free flight dynamics of bodies, such as sports equipment or human movement, face challenges in accurately measuring net forces and moments without invasive procedures, often resulting in errors due to skin movement artifacts and the need for cumbersome equipment.
Innovation Solution
The use of miniature inertial measurement units (IMUs) that directly measure acceleration and angular velocity, allowing for the computation of forces and moments through inverse dynamics, reducing the need for extensive differentiation and minimizing errors, and providing a portable, non-invasive solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional motion capture methods are used to measure joint kinetics, then measurement coverage is comprehensive, but measurement precision deteriorates due to skin movement artifacts and extensive differentiation requirements
Solution Approach 1:
The patent extracts the measurement function from complex external motion capture systems and embeds it directly into the subject being measured through implanted sensors. This eliminates skin movement artifacts by placing accelerometers and gyroscopes inside the body segment, directly measuring bone motion without soft tissue interference.
Solution Approach 2:
The patent introduces an intermediary processing unit that receives raw acceleration and angular velocity data from sensors, performs centralized computation of joint kinetics through inverse dynamics, and outputs processed results. This intermediary handles the complex differentiation and integration operations centrally rather than requiring complex distributed measurement systems.
2Measurement precision
If invasive surgical procedures are performed to directly measure joint forces, then measurement precision improves, but ease of operation deteriorates due to surgical requirements
Solution Approach 1:
The patent uses small, inexpensive, disposable or temporarily implantable sensor modules that can be inserted through minimally invasive procedures. These compact accelerometers and gyroscopes are designed to be easily implanted and removed without requiring major surgical intervention, making the system both precise and operationally simple.
3Loss of information
If extensive differentiation is performed on position data to obtain joint kinetics, then comprehensive kinematic information is obtained, but reliability deteriorates due to error amplification
Solution Approach 1:
Instead of measuring position and performing multiple differentiations to obtain velocity and acceleration, the patent inverts the approach by directly measuring acceleration and angular velocity with sensors, then integrating once to obtain velocity and position. This inversion reduces the number of differentiations from multiple orders to a single integration step, significantly reducing error amplification while preserving complete kinematic information.
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 enhances accuracy and portability while reducing costs, enabling effective analysis of forces and moments on sports equipment and human body segments during various activities, including sports training and injury prevention.
Implementation Method 1
an inertial measurement unit having at least one accelerometer continuously measuring three orthogonal axes of acceleration
Implementation Method 2
the joint kinetics can be deduced using inverse dynamics
Data Source
AI summary
An apparatus for analyzing free flight of a body including an inertial measurement unit having at least one accelerometer continuously measuring three orthogonal axes of acceleration and outputting data representative thereof and a processing unit operably receiving the data and determining three components of an angular velocity of the body during free flight.