Variable Stiffness Supernumerary Robotic Limbs for Overhead Support
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Solution Overview
Problem
In tasks requiring overhead assembly and support, large-scale mechanical apparatuses struggle to assist due to operational environment limitations, leading to labor shortages and increased risk of fatigue injuries, as existing supernumerary robotic limbs either fail to enlarge the working space or restrict limb movement.
Innovation Solution
An auxiliary support method utilizing variable stiffness supernumerary robotic limbs that coordinates with the human arm's stiffness, determined by real-time data from surface electromyography and inertial sensors, to adjust the robotic limbs' supporting force, reducing personnel input and fatigue risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large-scale mechanical apparatuses are used for overhead assembly and support, then work intensity is reduced, but they cannot adapt to complex operation environments with high flexibility requirements
Solution Approach 1:
The system divides the support function into two segments: human operator provides intentional control and flexibility, while the supernumerary robotic limb provides mechanical support force. This segmentation allows each component to operate in its optimal domain, resolving the contradiction between productivity and adaptability.
Solution Approach 2:
The patent introduces an intermediary control system that includes sEMG sensors, inertial sensors, and impedance control algorithms. This intermediary layer translates human intentions into robotic actions while coordinating stiffness parameters, enabling the robotic limb to adapt to complex environments while providing mechanical support.
2Volume of moving object
If existing supernumerary robotic limbs are used, then workspace is enlarged, but limb movement is restricted
Solution Approach 1:
The patent applies dynamic stiffness adjustment where the robotic limb's impedance parameters are continuously modified based on real-time sEMG signals and operational conditions. This dynamic adaptation allows the limb to provide rigid support when needed while maintaining movement freedom when the operator requires active control, resolving the workspace vs. movement freedom contradiction.
Solution Approach 2:
The system changes the stiffness parameter of the robotic limb dynamically based on operational requirements. When the operator is tired or performing heavy lifting, the stiffness parameter increases to provide greater support. When active manipulation is needed, the stiffness decreases to allow smoother movement, thus resolving the contradiction between workspace enlargement and movement freedom.
3Device complexity
If fixed stiffness robotic limbs are used, then control is simplified, but they cannot provide adaptive support during fatigue
Solution Approach 1:
The patent implements a feedback control system that continuously monitors sEMG signals from the operator's muscles and adjusts the robotic limb's stiffness in real-time. When muscle activation patterns indicate fatigue, the system automatically increases support. This feedback mechanism resolves the contradiction by adding reliability through adaptive support while keeping the control interface simple for the operator.
Solution Approach 2:
The robotic limb performs self-adjustment based on sensor feedback without requiring complex manual control from the operator. The system automatically detects operational conditions and modulates its own impedance parameters, providing adaptive support during fatigue while maintaining simple user interaction. This self-service capability resolves the contradiction between control simplicity and adaptive support reliability.
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 method enables efficient man-machine cooperation by dynamically adjusting the robotic limbs' stiffness to support tasks, reducing the need for multiple workers and minimizing fatigue injuries by increasing supporting force when the wearer is tired.
Implementation Method 1
obtaining in real time original output data from a surface electromyography sensor and an inertial sensor placed on an arm of a wearer
Implementation Method 2
obtaining in real time original output data from a surface electromyography sensor and an inertial sensor placed on an arm of a wearer
Data Source
AI summary
An auxiliary support method based on variable stiffness supernumerary robotic limbs includes: obtaining data from a surface electromyography sensor and an inertial sensor; processing the data from the inertial sensor to determine whether a wearer has an operation intention; preprocessing the data from the surface electromyography sensor through full-wave rectification, low-pass filtering and normalization; using preprocessed surface electromyography to estimate a reference stiffness of an arm of the wearer; and mapping the reference stiffness of the arm to an impedance control model of the supernumerary robotic limbs. In the method, man-machine cooperation between human and the supernumerary robotic limbs in a task of overhead support is achieved by coordinating a stiffness of the human arm and a stiffness of the supernumerary robotic limbs, thereby reducing input of personnel in the task; and when the stiffness of the arm of the wearer decreases, the stiffness of the supernumerary robotic limbs increases.