Stairlift Armrest Position Control for Passenger Safety

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Solution Overview

Problem

Existing stairlifts lack effective safety measures to ensure passengers are securely positioned, particularly when the armrests are not in the correct position for securing the person, which can lead to safety hazards during operation.

Innovation Solution

The stairlift incorporates an angular sensor to detect the armrest's position and a latch mechanism to lock the armrest in secure positions. The control unit adjusts the functionality of the drive assembly based on the armrest's position, ensuring safety by blocking or altering the drive or swivel mechanisms as necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the armrest is made foldable to save space, then the storage space efficiency is improved, but the safety of securing the passenger deteriorates

Engineering Contradiction:
Improvestorage spaceVSAvoidsafety of securing passenger
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The armrest is designed to be dynamically adjustable between folded and unfolded positions. During operation, it can be unfolded to provide safety, while during storage it can be folded to save space. This dynamic adaptability resolves the contradiction between space efficiency and safety.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

A sensor detects the armrest position and provides feedback to the control unit. The control unit uses this information to determine whether the armrest is in a safe position for passenger securing, enabling automated safety control based on the actual armrest state.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the armrest is positioned radially outward to support passenger entry, then the ease of operation is improved, but the safety of securing the passenger deteriorates

Engineering Contradiction:
Improveease of passenger entryVSAvoidsafety of securing passenger
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The armrest can dynamically change its radial position. During passenger entry, it extends radially outward to support the passenger. During operation, it retracts to a position that provides securing functionality. This dynamic repositioning resolves the contradiction between ease of entry and safety.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The armrest is positioned in the radially outward configuration in advance during the entry phase to facilitate passenger boarding. After entry is complete, it is repositioned to the securing configuration before the drive assembly operates, ensuring safety is established beforehand.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the control system monitors armrest position continuously, then the safety is improved, but the device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A simple sensor provides feedback on the armrest position to the control unit. This feedback mechanism enables continuous monitoring without requiring complex control systems, as the sensor directly reports the armrest state and the control unit makes straightforward decisions based on predefined safety criteria.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control unit automatically adjusts the functionality of the drive assembly based on the sensor feedback regarding armrest position. The system self-regulates by blocking or enabling drive functions according to the detected armrest state, eliminating the need for complex external monitoring or manual intervention.

Inventive Principle:
Principle #25Self-service

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

This solution enhances safety and comfort by ensuring the armrest is in a secure position before allowing the stairlift to operate, thereby preventing accidents and improving user security.

Implementation Method 1

The stairlift comprises an angular sensor for detecting the angular position of the armrest

Methodology Applied
Scientific EffectAngular detection:

Implementation Method 2

the chair comprises a, in particular a spring loaded, latch mechanism to lock the armrest in a, in particular in a discrete, angular position

Methodology Applied
Scientific EffectSpring loading: Spring

Implementation Method 3

When unfolding the armrest, the armrest is rotated downwards until it reaches a mechanical stop and the armrest stays in this position due to gravitational forces

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3592683B1Method of controlling a stairlift and a stairlift
Publication Date: 2025.04.23 TK HOME SOLUTIONS BV
  • EP3592683B1 patent drawingFigure 1a~2
  • EP3592683B1 patent drawingFigure 3~4
  • EP3592683B1 patent drawingFigure 5~6

AI summary

Method of controlling a stairlift (1), the stairlift (1) comprises a rail (2), a chair (4), a drive assembly (3) having a drive engine (22) for driving the chair (4) along the rail (2), the chair (4) is attached to the drive assembly (3), the chair (4) having an armrest (5), wherein the armrest (5) is pivotably supported at the chair (4) by a hinge (8), which allows a rotational movement of the armrest (5), in particular along a vertical axis (R), the method comprising the step of detecting an angular position (A-D) of the armrest (5); the step of controlling at least one functionality of the stairlift (1), in particular a functionality of the drive assembly (3), as a function on the detected angular position (A-D).