Flexure mechanisms for upper-limb support: Towards compliant wearable assistive devices

Martin Tschiersky

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Gravity-compensating wearable assistive devices for the upper limb dynamically support the weight of their wearer’s arms and that of manipulated objects, and thereby reduce the effort to raise the arms and to maintain certain poses.
They are used by people suffering from reduced muscle strength to restore their ability to execute manual tasks, and by healthy users to prevent injury or to enhance their physical capabilities.

Traditionally, these devices are designed as rigid-link mechanisms that form a supporting structure around the body.
This rigid-link architecture offers several advantages, mainly with respect to the transmittable power and load capacity, but often negatively affects the wearing comfort and aesthetic appearance.

To address this issue, this thesis investigates the use of flexible mechanisms for upper-limb support.
In these mechanisms, flexible structures simultaneously act as energy-storing springs, as complex transmission mechanisms, and as the load-bearing structure.

Two research tracks are explored.
The first deals with passive mechanisms that use flexible structures to achieve gravity compensation without the use of external power.
To this end, close-to-body compliant spring mechanisms for gravity balancing of the forearm and upper arm were synthesized.

The second deals with active, i.e., powered mechanisms that use flexible structures to enable compact actuator designs.
To that effect, a bending actuator was created which features a low height that makes it potentially wearable underneath clothing.

The devices are validated in simulation and experiment, and potential applications are illustrated by proof-of-concept prototypes.
Furthermore, the developed synthesis methodology which uses numerical multibody models together with global optimization techniques provides a conceptual framework for future research.
Thus, this thesis presents a promising new approach for building well-performing, close-fitting and comfortable upper-limb wearable assistive devices based on flexible mechanisms.
Original languageEnglish
QualificationDoctor of Philosophy
  • Brouwer, Dannis Michel, Supervisor
  • Herder, J.L., Supervisor
  • Hekman, Edsko E.G., Co-Supervisor
Award date30 Apr 2021
Place of PublicationEnschede
Print ISBNs978-90-365-5134-2
Publication statusPublished - 30 Apr 2021


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