Upper-Limb Assistive Linkage for Flexible High-Torque Lifting
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Solution Overview
Problem
Existing active upper-limb assistive devices suffer from stiff movements, limited lifting moment arms, and unsatisfactory torque output, leading to ergonomic discomfort, reduced operational efficiency, and increased risk of safety accidents and health issues like lumbar muscle strain.
Innovation Solution
A wearable active powered upper-limb assistive device with a flexible connection structure between the upper support arm and torso exoskeletal frame, incorporating an upper-limb linkage assembly and assistive lifting linkage assembly to enhance movement flexibility, stability, and torque output, featuring adjustable support assistance and adaptable components for diverse operational scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotary shaft coupling is used to connect the upper support arm and the torso exoskeletal frame, then the connection is simple and stable, but the movement flexibility is limited and the device feels stiff
Solution Approach 1:
The connection between the upper support arm and torso exoskeletal frame is divided into multiple segments: a rotary shaft coupling for basic rotation and a flexible connection structure (suspension rod or elastic element) for additional movement freedom. This segmentation allows each component to perform its specialized function while collectively providing both simplicity and flexibility.
Solution Approach 2:
The connection structure transitions from a static rotary shaft coupling to a dynamic system that combines rotary motion with flexible deformation. The flexible connection structure allows the upper support arm to adapt its position dynamically based on user movement needs, providing stiffness when needed and flexibility when required.
2Force
If a short lifting moment arm is used in the active assistive device, then the device structure is compact, but the output torque is small and assistive support is unsatisfactory
Solution Approach 1:
The lifting moment arm is extended by utilizing the vertical dimension through the suspension rod connecting the waist bag to the upper support arm. This creates a longer effective moment arm that increases output torque while maintaining a compact horizontal footprint of the device structure.
Solution Approach 2:
The suspension rod acts as an intermediary element that transmits force from the waist bag (driven by the motor) to the upper support arm over an extended distance. This intermediary structure enables the motor to generate sufficient torque at a distance from the joint, providing strong assistive support without requiring the motor to be positioned far from the user's body.
3Ease of operation
If the upper support arm is rigidly connected to the torso exoskeletal frame, then the structural stability is high, but the user experiences ergonomic discomfort and the device limits operational duration
Solution Approach 1:
The flexible connection structure using suspension rods or elastic elements provides a compliant interface between the rigid upper support arm and torso exoskeletal frame. This flexible connection absorbs movement discrepancies and adapts to user physiology, significantly improving ergonomic comfort while maintaining sufficient structural stability through the combined rigidity of the support arm and stabilization mechanisms.
Data Source
AI summary
A wearable active powered upper-limb assistive device includes a torso exoskeletal frame configured to be worn by an operator and a waist bag for the operator to wear around a waist, where the torso exoskeletal frame is connected with an upper support arm, the upper support arm is flexibly connected to the torso exoskeletal frame, an upper-limb linkage assembly is connected between the waist bag and the upper support arm, and the upper support arm is further drivingly coupled to an assistive lifting linkage assembly.