Motion-Based Wheelchair Power Assist With Push Detection

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Solution Overview

Problem

Existing power assist systems for manual wheelchairs either eliminate the need for manual propulsion, complicate the design with force and torque sensors, increase weight and cost, or pose safety hazards, failing to provide a balanced assist that maintains user engagement and mobility.

Innovation Solution

A motion-based power assist system that uses kinematic sensors to recognize user pushes and braking through angular and linear velocities and accelerations, providing assistive force-pulses based on these measurements, without relying on force or torque sensors, and is designed for easy attachment and detachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force and torque sensors are used to recognize user pushes, then propulsion assistance can be provided, but device complexity and weight increase significantly

Engineering Contradiction:

Improvepropulsion assistanceVSAvoidsensor system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical force/torque sensors with a motion-based sensing system that uses accelerometers and gyroscopes to detect wheel motion. This substitution eliminates the need for complex force measurement hardware while still achieving reliable propulsion assistance through motion detection and processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces motion sensors (accelerometers and gyroscopes) as intermediaries between the user's pushing action and the power assist system. These sensors detect the motion consequences of pushing rather than directly measuring force, providing a simpler pathway to trigger assistance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If force and torque sensors are mounted on handrims, then push detection is accurate, but handrim mounting complexity increases and weight increases

Engineering Contradiction:

Improvepush detection accuracyVSAvoidhandrim assembly weight

Core Design Contradiction:

Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent replaces force sensing mechanisms with motion sensing using accelerometers and gyroscopes mounted on the wheel hub or frame. This substitution maintains detection accuracy while eliminating the need for complex force measurement hardware on the handrim, thereby reducing weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent shifts the measurement dimension from force (vertical/rotational) to motion (linear acceleration and angular velocity). By measuring the motion consequences of pushing rather than the force itself, the system achieves accurate detection without requiring force-sensitive components on the handrim.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If power assist system completely eliminates manual pushing, then propulsion effort is reduced, but user engagement and psychological benefits are lost

Engineering Contradiction:

Improvepropulsion effortVSAvoiduser engagement

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The patent implements partial power assistance rather than complete automation. The system provides assistive torque only when pushes are detected, allowing users to maintain manual propulsion control and engagement while reducing the physical effort required. This partial assistance approach preserves user autonomy and psychological benefits.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent uses motion-based feedback to dynamically adjust power assistance based on user pushing actions. The system continuously monitors wheel motion and provides corresponding assistive torque, creating a responsive feedback loop that maintains user engagement while reducing effort. The feedback mechanism ensures users remain actively involved in propulsion control.

Inventive Principle:

Principle #23Feedback

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 user effort while maintaining manual propulsion benefits, enhances safety, and reduces weight and complexity, allowing easy transport and efficient battery use.

Implementation Method 1

The system uses different kinematic sensors, not force or torque sensors like the prior art, in order to measure when the wheelchair is accelerating past a certain minimal threshold

Methodology Applied

Scientific EffectKinematic sensing: Accelerometer

Implementation Method 2

The system then provides an assistive force-pulse that is related to the experienced acceleration and velocity from propulsion

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS12447076B2Motion-based power assist system for wheelchairs

Publication Date: 2025.10.21 MAX MOBILITY LLC

AI summary

A motion-based push activation power assist system for manual wheelchairs. The system uses motion-based measurements to determine when the user applies a push to the wheelchair handrims and brakes with the handrims. The push recognition activates a drive system that provides an assistive driving force-pulse to the wheelchair to reduce the demand on the user during propulsion. The brake recognition deactivates the power assist. The provided power assist is proportional to the sensed push and can be modulated to different proportional settings.