Community Research and Development Information Service - CORDIS

Final Report Summary - SENSPRO (Sensory Feedback for Improved Prosthesis Control)

Functional substitution of a lost limb is necessary for persons with an upper-limb amputation to perform daily life explorations and manipulations in their environment. The ultimate goal of this study is to improve prosthesis control with appropriate sensory feedback. Towards this goal, the objectives of this study are (1) to identify relative contributions of the sensory feedback modalities (vision, proprioception, artificial proprioception) on coordinated manipulations, and (2) to develop and evaluate sensory feedback systems for persons with an upper-limb amputation. It was planned to reach the objectives of this project by pursuing two work packages.

In the first work package, the effect of sensory substitution of force and position feedback on a two-degree-of-freedom dynamic finger flexion task were evaluated. For this purpose, a new methodology and a novel haptic interface have been developed. The experimental methodology was based on the “Strength-Dexterity Test” working on the principle of buckling of compression springs. A psychophysical test was conducted where subjects interacted with a virtual spring with the index finger of their dominant hand through either the haptic interface, an input device, or a force sensor in either isotonic or isometric mode. Three feedback conditions were tested: no sensory substitution, modality-matched sensory substitution, and modality-mismatched sensory substitution (through vibration). Sensory substitution feedback was provided on subjects' contralateral arm. Results show that sensory substitution of force and position did not have a significant contribution to subjects' performance in the proposed dynamic task. The outcomes of this work package are a prototype haptic interface, a poster presentation at the IEEE Haptics Symposium 2016, an M.S. thesis, and a manuscript under review in an SCI-E indexed journal.

In the second work package, two novel tactile interfaces have been developed for providing appropriate sensory information to persons with an upper-limb amputation: (1) a tapping tactor displaying contact information, and (2) a skin stretch tactor displaying wrist proprioception.

Considering that touch feedback plays a significant role in identifying contacted objects, the tapping tactor was used to apply contact signals on the clavicle bone. First, a library of accelerations occurring as a result of tapping on different materials has been prepared. A stochastic signal model has been developed for the contact accelerations. Due to the distinct waveform characteristics of different materials, the rate of change of acceleration was used to identify hardness of the objects. In a psychophysical study, the whole procedure of recording, identifying, and replaying the signals was investigated. Results of this study showed the ability of the designed tactor to provide distinguishable hardness sensations of different materials in real time. Furthermore, considering the results of the position control test with and without vision, it was shown that the proposed contact sensory feedback method could be enough to substitute for vision during simple grasping tasks. This study was presented at the IEEE Haptics Symposium 2014, and published in one of the leading academic journals of the field, the IEEE/ASME Transactions on Mechatronics, in its August 2017 issue. One of the outcome was also an M.S. thesis.

As the second tactile interface, a novel skin stretch tactor and an original method has been developed to provide skin stretch feedback of three degree-of-freedom wrist movements, which are extension-flexion, radial-ulnar deviation and pronation-supination, to prosthetic hand users. In order to evaluate the performance of the device, a test setup has been built. By means of two bracelets and two actuators, six motions of the wrist could be provided via the tactor. A user study with able-bodied participants was conducted. Confusion matrices were created from the experimental data, and the results were analyzed in terms of correct identification of the intended stimulations. Analysis showed that the proposed design together with the sensory feedback method was a viable option for proprioceptive feedback lacking in robotic prosthetic hands. This study was presented at the IEEE Haptics Symposium 2018.

The rationale underlying this research was that identifying the role of sensory feedback on human-machine interaction control and demonstrating whether its sensory substitution has any benefit on movement control provided ways to improve prosthesis control. The results have valuable contributions to the EU community at different fronts. In the scientific arena, findings advanced the general understanding of human sensory feedback system, and contributed to the European scientific excellence in neuroscience. Moreover, the results developed several technologies and devices for prosthesis users. This way, the results of this research contributed to the health and wellbeing of the society.

For further correspondence:
Project website:
Researcher: Assist. Prof. Evren Samur,
Bogazici University, Department of Mechanical Engineering, 34342 Bebek, Istanbul, Turkey

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Life Sciences
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