Abstract
This thesis investigates the ways how behavioural examination strategies are used to enhance tactile perception during examination of soft viscoelastic environments. During the last few decades, Robot-assisted Minimally Invasive Surgery (RMIS) has become increasingly popular and has been employed in various medical procedures with proven benefits for the patient. However, direct tactile feedback which greatly improves surgical outcomes is not present in RMIS.Artificial probing performed on ex-vivo and phantom tissues shows high variability in the obtained data. Variability is caused by non-homogeneous tissue stiffness and the resulting nonlinear temporal dynamics of tool indentation. Performed numerical simulations indicate that probing speed for fixed indentation influences the variability of tissue viscoelastic parameter estimation. To reduce variability in artificial tactile examination, suitable probing behaviour should be implemented. Three techniques of manual palpation are studied to understand the behavioural patterns of soft tissue tactile examination, namely, modulation of the applied force, localised, and global examination.
Humans use force modulation strategies to enhance their perception of harder areas in non-homogeneous environments. A second-order reactive autoregressive model has been found to describe this type of technique. Robotic palpation showed how this technique enhances the perceived inhomogeneous stiffness of the environment.
The study of unidirectional localised manual palpation, has shown that combinations of force-velocity strategies can be used to enhance the perception of hard formations in viscoelastic environments. To validate the obtained probing strategies, finite element simulations and tele-manipulated palpation were used. It was found that kinaesthetic and/or force feedback are used by humans to detect hard formations.
Finally, a remote palpation procedure on a silicone phantom utilizing a tele-manipulation setup was performed to study the behaviour of remote global palpation. The results demonstrate the effectiveness of global palpation pattern used during manual soft tissue examination as well as in tele-manipulated palpation.
| Date of Award | 2015 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Thrishantha Nanayakkara (Supervisor) & Kaspar Althoefer (Supervisor) |