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Research Papers

Wheelchair Models With Integrated Transfer Support Mechanisms and Passive Actuation

[+] Author and Article Information
Lorenzo T. D’Angelo

Institute of Micro Technology
and Medical Device Technology,
Technische Universitaet Muenchen,
Garching 85748, Germany
e-mail: Lorenzo.DAngelo@mytum.de

Kassim Abdul-Sater

Institute of Micro Technology
and Medical Device Technology,
Technische Universitaet Muenchen,
Garching 85748, Germany
e-mail: Kassim.Abdul-Sater@tum.de

Florian Pfluegl

Institute of Micro Technology
and Medical Device Technology,
Technische Universitaet Muenchen,
Garching 85748, Germany
e-mail: PfFlorian@mytum.de

Tim C. Lueth

Institute of Micro Technology
and Medical Device Technology,
Technische Universitaet Muenchen,
Garching 85748, Germany
e-mail: Tim.Lueth@tum.de

1Corresponding author.

Manuscript received May 21, 2014; final manuscript received December 31, 2014; published online January 29, 2015. Assoc. Editor: Carl Nelson.

J. Med. Devices 9(1), 011012 (Mar 01, 2015) (13 pages) Paper No: MED-14-1183; doi: 10.1115/1.4029507 History: Received May 21, 2014; Revised December 31, 2014; Online January 29, 2015

The concept presented in this paper describes two new approaches to integrate transfer support functions into wheelchairs. The goal is to relieve caregivers and nurses in their daily task of lifting patients from and to the wheelchair without the need of an additional external lift device, such as commonly used lifting cranes or lifting belts. The contributions of this paper are (i) the design of two different mechanical linkages, which realize two types of transfer motions, (ii) the selection of a passive actuator for weight compensation and simulation of the force induced by it (static design), as well as (iii) the experimental evaluation of the simulation using rapid prototyping functional models of the concepts. The results are two different design concepts, each of which can realize a particular, smooth transfer motion.

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References

Figures

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Fig. 1

(a) Planar depiction of the starting configuration of the concept sit to stand. (b) Planar depiction of the ending configuration of the concept sit to stand.

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Fig. 2

Kinematic sketch of the sit to stand concept

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Fig. 3

(a) Spatial depiction of the starting configuration of the concept sit to stand. (b) Spatial depiction of the ending configuration of the concept sit to stand.

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Fig. 4

(a) Planar depiction of the starting configuration of the concept horizontal transfer. (b) Planar depiction of the ending configuration of the concept horizontal transfer.

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Fig. 5

Kinematic sketch of the horizontal transfer concept

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Fig. 6

(a) Spatial depiction of the starting configuration of the concept horizontal transfer. (b) Spatial depiction of the ending configuration of the concept horizontal transfer.

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Fig. 7

(a) Starting and ending configuration of the sit to stand concept. (b) Starting and ending configuration of the horizontal transfer concept.

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Fig. 8

(a) Construction of both four-bar linkages for the sit to stand concept. (b) Construction of the gas pressure spring for the sit to stand concept.

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Fig. 9

Four-position synthesis of the seat pan guidance linkage using two intermediate positions of the seat pan

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Fig. 10

Simulation of starting, ending, and intermediate configurations of the sit to stand concept. The positions of the simulated center of gravity and the chair-fixed center of gravity used in the force calculations are highlighted.

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Fig. 11

(a) Force calculation for the sit to stand concept. The figure is qualitative, as not all positions reflect the final resulting lengths and angles. (b) Balance of forces affecting the seat pan for the sit to stand concept. The figure is qualitative, as not all positions reflect the final resulting lengths and angles.

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Fig. 12

Progression of the mechanism’s angles for the sit to stand concept

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Fig. 13

Exemplary progression of force on the wheelchair G, resulting from the constant user weight m·g and the force applied by a carer Fcomp

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Fig. 14

Progression of forces for the sit to stand concept (required forces to lift a user weighting 80 kg)

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Fig. 15

(a) Construction of the backrest movement for the horizontal transfer concept. (b) Construction of the scissors mechanism for the horizontal transfer concept. (c) Construction of the legrest movement for the horizontal transfer concept.

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Fig. 16

Force calculation for the horizontal transfer concept

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Fig. 17

Progression of forces for the horizontal transfer concept (occurring forces and required user load G to keep the system stable with a given gas pressure spring profile without carer compensation force Fcomp)

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Fig. 18

(a) Rapid prototyping model (scale 1:4) of the horizontal transfer concept, upper position. (b) Rapid prototyping model (scale 1:4) of the horizontal transfer concept, lower position. (c) Rapid prototyping model (scale 1:4) of the horizontal transfer concept, measurement setup.

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Fig. 19

Progression of measured and calculated (see Fig. 16) load of user G for the horizontal transfer model

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Fig. 20

(a) Model of the sit to stand concept (scale 1:1), side view. The tape measure is unrolled to a length of 1 m. (b) Model of the sit to stand concept (scale 1:1), front view. The tape measure is unrolled to a length of 1 m. (c) Model of the sit to stand concept (scale 1:1), back view. The tape measure is unrolled to a length of 1 m.

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