Hip-Coupled Exoskeleton Leaf-Spring Energy Transfer
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Solution Overview
Problem
Conventional unpowered compliant exoskeletons are ineffective in reducing the metabolic rate during running, as they primarily support the ankle joint, whereas in running, the hip joints contribute equally and require significant support to minimize metabolic energy consumption.
Innovation Solution
An unpowered compliant exoskeleton with a leaf-spring mechanism that dynamically couples the hip joints, transferring energy from one hip to the other during the swing phase to reduce muscle activity and metabolic rate, utilizing a rack-and-pinion gear mechanism to adjust the leaf-spring's arc and optimize energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional unpowered compliant exoskeletons support the ankle joint, then they can reduce metabolic rate during walking, but they are ineffective in reducing metabolic rate during running
Solution Approach 1:
The exoskeleton is segmented to provide independent support at different joint locations. The device can be configured with ankle joint support for walking and hip joint support for running, allowing each segment to be optimized for specific gait requirements rather than attempting to support all gait types uniformly
Solution Approach 2:
The exoskeleton employs dynamic compliance through elastic elements that adapt to different gait patterns. The compliant mechanism allows the device to dynamically adjust its support characteristics based on the user's movement pattern, transitioning between walking and running modes without rigid mechanical constraints
2Use of energy by moving object
If elastic elements absorb and recycle energy in cyclic motion, then metabolic energy consumption is reduced, but the supportive torque provided is insufficient compared to powered exoskeletons
Solution Approach 1:
The exoskeleton changes the stiffness parameter of its elastic elements to optimize performance. By adjusting the compliance characteristics of the spring mechanisms, the device can provide adequate supportive torque for the specific task while maintaining energy recycling capabilities, rather than using fixed rigid or purely compliant structures
3Force
If powered exoskeletons utilize motors and actuators to exert assistive forces, then they can provide adequate supportive torque, but they require power supply and have complex design
Solution Approach 1:
The exoskeleton uses the user's own motion to drive the energy recycling mechanism. The elastic elements are passively activated by the user's natural gait movements, eliminating the need for external power sources, motors, or actuators while still providing force assistance through stored and released elastic energy
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 exoskeleton effectively reduces metabolic rate by recycling energy between hip joints, minimizing muscle energy usage and extending running performance by reducing negative work and energy dissipation, as demonstrated in test results showing a 10.2% reduction in metabolic rate with the exoskeleton compared to running without it.
Implementation Method 1
A class of unpowered exoskeletons are unpowered compliant exoskeletons (UCEs) which relay on their elastic structures in order to facilitate a user's motions. Elastic element of the UCEs absorb a part of energy in a phase of motion and recycle it on the other phase.
Implementation Method 2
utilizing a rack-and-pinion gear mechanism to adjust the leaf-spring's arc and optimize energy transfer
Data Source
AI summary
An exoskeleton comprising a right hip attachment, a left hip attachment, a belt and a leaf-spring. The leaf-spring configured to couple two hips and apply torque from one respective hip to another respective hip based on the runner's movement and a right gear mechanism and a left gear mechanism, the right gear mechanism and the left gear mechanism comprising respectively of rack-and-pinion mechanism and configured to change an arch of the leaf-spring.