Walking Assist Device Knee Collapse Detection

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Solution Overview

Problem

Existing walking assist devices may incorrectly distinguish between standing and swinging phases of a user's walking motion, leading to inappropriate resistance force application and inadequate assistance when the knee collapses during walking.

Innovation Solution

A walking assist device with a knee collapse sensing unit that detects when the knee joint is forward of the waist during the standing phase, adjusting the resistance force to ensure sufficient support by reducing or maintaining the decrease in resistance force, and optionally using upper leg posture angle or knee position sensors for accurate detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the resistance force is decreased when transitioning from standing phase to swinging phase, then the walking assist device can normally assist the walking motion, but when the knee collapses the device cannot provide sufficient support

Engineering Contradiction:

Improvewalking assist functionVSAvoidsupport capability during knee collapse

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system continuously monitors knee joint position during the standing phase and provides feedback to the control unit. When knee collapse is detected (knee joint positioned forward of waist portion), the control unit adjusts the resistance force accordingly by reducing or stopping its decrease, ensuring sufficient support is maintained during abnormal gait patterns

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The resistance force is dynamically adjusted based on real-time detection of knee joint position and walking phase. The system transitions from a static resistance profile to a dynamic one that adapts to the user's actual gait state, increasing support when knee collapse is detected and normalizing support during proper walking transitions

Inventive Principle:

Principle #15Dynamics

2Productivity

If displacement sensors are used to distinguish walking phases, then the device can control resistance force, but knee collapse causes erroneous phase distinction

Engineering Contradiction:

Improvewalking phase detection capabilityVSAvoidwalking phase distinction accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary detection of knee joint position during the standing phase before the transition to swinging phase occurs. By monitoring knee position in advance and comparing it against the waist portion reference point, the system can identify knee collapse conditions before they result in erroneous phase detection, preventing incorrect resistance force adjustments

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230022930A1Walking assist device, control method, and storage medium

Publication Date: 2023.01.26 TOYOTA JIDOSHA KK

AI summary

A walking assist device applies resistance force to a movement of a knee joint of a user according to a walking state of the user to assist a walking motion of the user. The walking assist device includes an auxiliary control unit that decreases the resistance force applied to the movement of the knee joint of the user when the walking state of the user transitions from a standing phase to a swinging phase, and a knee collapse sensing unit that senses a knee collapse by detecting that the knee joint of the user is located forward of a waist portion of the user during the standing phase. When the knee collapse sensing unit senses the knee collapse, the auxiliary force control unit reduces a degree of a decrease in the resistance force or stops the decrease in the resistance force.