3D Model Repositioning for Movement Amplitude Determination
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Solution Overview
Problem
Current digital vision methods for determining the amplitude of a movement performed by an articulated body, such as a patient during medical rehabilitation, face accuracy issues and lack robustness, especially when the patient's position deviates from the predetermined representation, leading to insufficient measurement accuracy.
Innovation Solution
A method and device that obtain a segment representative of the member's positioning, generate a three-dimensional model, and reposition it to minimize error between the model and a cloud of three-dimensional points from depth information, allowing for accurate determination of movement amplitude. This involves skeletal estimation, filtering, and post-processing to improve accuracy and realism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a depth sensor of the Kinect type is used to acquire measurements, then the acquisition speed is improved, but the robustness deteriorates when the patient's position is not in compliance with a predetermined representation
Solution Approach 1:
The patent transitions from 2D image processing to 3D spatial modeling by generating a three-dimensional model of the body member and comparing it with a cloud of 3D points from depth sensor data. This dimensional enhancement allows the system to handle various patient positions more robustly while maintaining fast acquisition speeds, as the 3D model can be repositioned through rotation and translation operations to match the actual body configuration.
2Measurement precision
If conventional goniometer measurements are used, then the measurement accuracy is maintained, but the acquisition speed deteriorates
Solution Approach 1:
The patent replaces the mechanical goniometer system with a digital vision system that uses depth sensors and 3D modeling. The mechanical measurement process is substituted by capturing depth information, generating a 3D model, repositioning it through computational operations, and extracting movement amplitude from the model's orientation changes. This substitution maintains measurement accuracy while dramatically improving acquisition speed.
3Measurement precision
If a three-dimensional model is generated and repositioned to minimize error criterion, then the measurement accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-defining the 3D model structure and preparing the error minimization framework before actual measurement. The model is pre-configured with appropriate geometric parameters, and the optimization algorithm is pre-established, allowing rapid processing during actual measurements without recalculating fundamental parameters.
Solution Approach 2:
The patent uses a simplified 3D model as a copy or representation of the actual body member. This model copy contains the essential geometric features needed for measurement but omits unnecessary details, reducing computational complexity while maintaining measurement accuracy. The model can be quickly repositioned and compared with sensor data without processing the full complexity of the actual body geometry.
Data Source
AI summary
A method for determining the amplitude of a movement performed by a member of an articulated body comprises:obtaining a segment representative of the positioning of the member in a given reference frame at the end of said movement,generating a three-dimensional model of the member, positioned in said reference frame by means of the obtained segment,obtaining a cloud of three-dimensional points representing the member in said reference frame at the end of said movement, based on depth information provided by a sensor, said depth information defining a three-dimensional scene comprising at least a part of the articulated body including said member,repositioning the model of the member so as to minimize a predetermined error criterion between the obtained cloud of points and said model, anddetermining the amplitude of the movement, based on the new positioning of the model of the member.