Powered Lower Extremity Orthotic with Segmented Actuation

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Solution Overview

Problem

Existing orthotic devices struggle to provide sufficient powered assistance for walking, particularly in knee and hip movements, while minimizing discomfort and restricting degrees of freedom, and fail to effectively prevent foot drop in individuals with impaired muscular function.

Innovation Solution

A powered lower extremity orthotic device with lightweight spars and unpowered pivots that distribute force more efficiently, along with a hip actuation system that avoids complex pelvic coupling and includes a motion reversing mechanism, and an ankle assistive mechanism with an electromechanical brake to prevent foot drop.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If powered actuators are used to provide sufficient force for knee and hip movements, then walking assistance is improved, but device complexity and discomfort increase

Engineering Contradiction:

Improvepowered assistance forceVSAvoiddevice complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The orthotic device is divided into multiple independent modules: knee actuators, hip actuators, and ankle mechanisms. Each module provides localized assistance without requiring a fully integrated complex system, reducing overall device complexity while maintaining sufficient force output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Passive mechanical elements such as springs, dampers, and linkages are introduced as intermediaries between the powered actuators and the user's body. These intermediaries transmit and modulate forces, reducing the complexity of direct actuator-to-body coupling while maintaining effective assistance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If powered actuators are used to provide sufficient force for knee and hip movements, then walking assistance is improved, but user comfort deteriorates

Engineering Contradiction:

Improvepowered assistance forceVSAvoiduser discomfort

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

Compliant interfaces and cushioning elements are incorporated at all contact points between the orthotic device and the user's body. This beforehand cushioning prevents discomfort and pressure points while allowing the powered actuators to deliver sufficient force for movement assistance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The device allows dynamic adjustment of actuator force output and mechanical impedance parameters. By changing these parameters in real-time based on user needs and gait phase, the system provides sufficient assistance force while minimizing discomfort and excessive constraint.

Inventive Principle:

Principle #35Parameter changes

3Force

If hip actuation system is implemented, then walking assistance is improved, but device complexity increases due to pelvic coupling requirements

Engineering Contradiction:

Improvehip assistance forceVSAvoidpelvic coupling complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The hip actuation system is extracted from the pelvic coupling structure and implemented as separate thigh-mounted actuators. This extraction eliminates the need for complex pelvic coupling mechanisms while still providing effective hip movement assistance through the thigh linkage.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of actuating the hips directly through pelvic coupling, the system inverts the approach by actuating the thighs and using passive mechanical linkages to transfer motion to the hips. This inversion simplifies the actuation architecture while achieving the same functional outcome.

Inventive Principle:

Principle #13The other way round (Inversion)

4Strength

If conventional orthotic devices are used, then structural support is provided, but foot drop prevention is insufficient

Engineering Contradiction:

Improvestructural supportVSAvoidfoot drop prevention

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The ankle mechanism incorporates preliminary action by maintaining the foot in a dorsiflexed position before toe-off through springs and dampers. This preliminary positioning prevents foot drop before it occurs, enhancing reliability while working within the existing structural support framework.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The ankle mechanism serves multiple functions: it provides structural support during stance, prevents foot drop during swing, and assists with toe-off. This multi-functionality improves foot drop prevention reliability without requiring additional dedicated components that would increase overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3068360B1Machine to human interfaces for communication from a lower extremity orthotic

Publication Date: 2020.07.08 EKSO BIONICS INC

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AI summary

A lower extremity orthosis is configured to be coupled to across at least one joint of a person for gait assistance and can incorporate knee (261), thigh (301; 401), hip (601; 701) and ankle/foot (801; 821) assistive orthotic devices which can be used in various combinations to aid in the rehabilitation and restoration of muscular function in patients with impaired muscular function or control.