Soft Knee Exoskeleton Using Negative-Pressure Actuation

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Solution Overview

Problem

Traditional lower limb exoskeletons are cumbersome, expensive, and pose safety risks due to mechanical inertia, making them unsuitable for individuals with knee joint injuries requiring partial walking assistance.

Innovation Solution

A soft knee exoskeleton driven by a negative-pressure linear actuator, utilizing a miniature vacuum pump and a sensing system comprising an inertial measurement unit, force sensor, and surface myoelectric sensor, for real-time control and torque assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid mechanism is used to drive the exoskeleton, then the weight-bearing capacity is enhanced, but the mechanical inertia causes safety risks and discomfort

Engineering Contradiction:

Improveweight-bearing capacityVSAvoidmechanical inertia

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional rigid mechanical driving mechanism with a pneumatic artificial muscle system. The pneumatic artificial muscles use compressed air to generate driving force, eliminating the mechanical inertia and rigid connections that cause safety risks. The soft robotic joints use flexible materials and pneumatic actuation instead of rigid motors and gears, fundamentally substituting the mechanical system with a pneumatic-soft system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs flexible materials throughout the exoskeleton structure, including soft robotic joints made of flexible shells and thin films. These flexible components replace rigid mechanical parts, allowing the exoskeleton to conform to the user's body movements while eliminating the harmful effects of mechanical inertia. The flexible structure maintains strength while removing the rigid connections that transfer inertial forces to the user.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If a traditional rigid exoskeleton is used, then the support function is provided, but the device becomes bulky and inconvenient to wear

Engineering Contradiction:

Improvesupport functionVSAvoidconvenience to wear

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent uses flexible shells and thin films to create a lightweight, form-fitting exoskeleton that conforms to the user's body. The soft robotic joints are made from flexible materials that can be easily molded to individual body shapes, making the device comfortable and convenient to wear. This flexible construction maintains the necessary support function while dramatically reducing bulkiness compared to rigid exoskeletons.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs pneumatic artificial muscles as the driving mechanism, which are significantly lighter and more compact than traditional electric motors and mechanical transmission systems. The pneumatic system provides sufficient driving force while reducing the overall weight and bulk of the exoskeleton, enhancing ease of wear and user comfort without compromising the support function.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Power

If a miniature vacuum negative pressure pump is used, then the power density is enhanced, but the system complexity increases

Engineering Contradiction:

Improvepower densityVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent integrates the miniature vacuum negative pressure pump, control system, and power supply into a unified wearable unit that is worn on the user's back. By merging these components into a single integrated system rather than separate external devices, the patent achieves high power density while managing system complexity through consolidation. The integrated design allows the control system to directly manage the pump and pneumatic artificial muscles without requiring complex external wiring or multiple independent systems.

Inventive Principle:

Principle #5Merging (Combining)

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 soft knee exoskeleton provides safe and comfortable walking assistance by overcoming mechanical inertia and enhancing power density, improving mobility for individuals with knee joint injuries.

Implementation Method 1

A soft knee exoskeleton driven by a negative-pressure linear actuator, utilizing a miniature vacuum pump

Methodology Applied

Scientific EffectNegative pressure: Vacuum

Data Source

PatentUS11497672B2Soft knee exoskeleton driven by negative-pressure linear actuator

Publication Date: 2022.11.15 BEIJING INST OF TECH

AI summary

The present invention discloses a soft knee exoskeleton driven by a negative-pressure linear actuator, including: an exoskeleton controller, a left leg knee joint soft actuator, a right leg knee joint soft actuator and the like. The soft knee exoskeleton mainly uses a miniature vacuum negative pressure pump as an air pressure power source. A DSP embedded control system performs real-time processing on the data, such as a muscle force, a knee joint angle and a human-machine interaction force, detected by a sensing system, estimates a human-machine cooperation state, and performs real-time control on the switching of the negative pressure flow and an air channel of the miniature vacuum negative pressure pump.