Upper-Body PHRI Interface for Spasticity-Aware Robot Coupling
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Solution Overview
Problem
Existing exoskeleton devices for upper-body rehabilitation, particularly for stroke recovery, face challenges in widespread use due to issues such as muscle spasticity, flexor synergy, and discomfort, which hinder their practicality and effectiveness.
Innovation Solution
A wearable robotic system with a Physical Human Robot Interaction (PHRI) interface that anchors the human limb, minimizes relative motion, transfers motion and force, ensures user comfort, and reduces adverse neuromuscular tendencies by directing palmar contact to less provocative regions, using a plastic-on-plastic ratcheting mechanism and quick disconnect feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional exoskeleton devices are used for upper-body rehabilitation, then mechanical power transfer occurs, but muscle spasticity and flexor synergy are exacerbated
Solution Approach 1:
The interface directs contact forces to specific regions of the hand (metacarpal heads and dorsal surface) that are less likely to trigger flexor synergy, rather than applying force uniformly across the entire hand. This localized force application reduces harmful neuromuscular responses while maintaining rehabilitation effectiveness.
Solution Approach 2:
Instead of applying force to the palm (which triggers flexor synergy), the interface applies force to the dorsal surface and metacarpal heads, essentially inverting the traditional contact approach. This reversal of force application location reduces muscle spasticity while maintaining mechanical power transfer.
2Reliability
If traditional exoskeleton interfaces are used, then mechanical coupling occurs, but user comfort is reduced
Solution Approach 1:
The interface uses a compliant material that distributes contact forces across multiple pressure distribution regions on the dorsal surface of the hand and metacarpal heads. This localized force distribution reduces pressure points and improves user comfort while maintaining effective mechanical coupling.
3Force
If rigid coupling is used to ensure mechanical power transfer, then force transfer improves, but adaptability to different users is reduced
Solution Approach 1:
The interface uses a compliant material that can change its mechanical properties (softness, pressure distribution) to adapt to different hand sizes and anatomical variations among users. This allows effective force transfer while accommodating individual user differences.
Solution Approach 2:
The compliant interface material dynamically adapts its deformation and pressure distribution based on the user's hand anatomy and the forces applied during rehabilitation exercises. This dynamic adaptation maintains effective coupling across different users without requiring rigid, one-size-fits-all design.
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 system effectively reduces muscle spasticity and flexor synergy, enhances user comfort, and facilitates easier attachment and detachment, thereby improving the usability and effectiveness of upper-body rehabilitation devices.
Implementation Method 1
plastic-on-plastic ratcheting mechanism
Data Source
AI summary
An embodiment includes an apparatus for coupling a user to a robot to provide robot-assisted physical therapy to the user. Other embodiments are described herein.