3D Spring Array Calibration Structure for Robot Impedance Verification
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Solution Overview
Problem
Current methods for measuring mechanical impedance in joints, such as those of stroke patients, rely heavily on human judgment, leading to variability and limitations in objective diagnosis, and existing robots face challenges in calibrating for accurate 3D mechanical impedance measurement.
Innovation Solution
A 3D spring array device connected to a mechanical impedance estimating robot, featuring a fixed body with a moving body and strategically positioned springs, which helps verify the reliability and accuracy of the robot's impedance measurements by minimizing numerical errors through optimal spring selection and configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical impedance estimating robot is used to measure mechanical impedance in three directions, then the objectivity and consistency of measurement are improved, but the difficulty of calibration and verification increases
Solution Approach 1:
The calibration device is segmented into a fixed body and a moving body with independent degree of freedom, allowing separate calibration of each spatial direction. The moving body can be controlled to move along the x, y, and z axes independently, enabling simplified step-by-step calibration procedures for the three-dimensional impedance measurement system.
Solution Approach 2:
A spring array system is introduced as an intermediary element between the fixed body and moving body. The springs provide known elastic forces that serve as reference standards for calibration, mediating the verification process between the robot's force sensors and the actual mechanical impedance being measured.
2Measurement precision
If springs are strategically positioned to minimize numerical errors in stiffness matrix, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The springs are positioned asymmetrically relative to the moving body's center of mass, with specific coordinates designed to create optimal geometric relationships. This asymmetric arrangement ensures that the stiffness matrix has minimal numerical errors while maintaining structural stability and ease of assembly.
Solution Approach 2:
The spring positioning extends into three-dimensional space with specific x, y, z coordinates, utilizing spatial dimensionality to optimize the stiffness matrix properties. By distributing springs throughout the 3D space rather than confining them to a single plane, the system achieves better numerical stability and 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
The 3D spring array device enhances the accuracy and reliability of mechanical impedance measurements by reducing the difference between diagonal and non-diagonal elements in the stiffness matrix, thereby minimizing numerical errors and improving the consistency of joint impedance assessments.
Implementation Method 1
at least one spring selected from a group consisting of a first spring, a second spring, a third spring, a fourth spring, a fifth spring, a sixth spring, a seventh spring, and an eighth spring and configured to connect the fixed body to the moving body
Data Source
AI summary
A 3D spring array device includes: a fixed body having an internal space therein; a moving body positioned in a center of an x-y-z orthogonal coordinate system in the internal space, wherein the moving body is configured to be fastenable to the end effector of the mechanical impedance estimating robot; and a first spring, a second spring, a third spring, a fourth spring, a fifth spring, a sixth spring, a seventh spring, and an eighth spring and configured to connect the fixed body to the moving body in the internal space.