Force-velocity modulation strategies for soft tissue examination

Advanced tactile tools in minimally invasive surgery have become a pressing need in order to reduce time and improve accuracy in localizing potential tissue abnormalities. In this regard, one of the main challenges is to be able to estimate tissue parameters in real time. In palpation, tactile information felt at a given location is identified by the viscoelastic dynamics of the neighboring tissue. Due to this reason the tissue examination behavior and the distribution of viscoelastic parameters in tissue should be considered in conjunction. This paper investigates the salient features of palpation behavior on soft tissue determining the effectiveness of localizing hard nodules. Experimental studies involving human participants, and validation tests using finite element simulations and a tele-manipulator, were carried out. Two distinctive tissue examination strategies in force-velocity modulation for the given properties of target tissue were found. Experimental results suggest that force-velocity modulations during continuous path measurements are playing an important role in the process of mechanical soft tissue examination. These behavioral insights, validated by detailed numerical models and robotic experimentations shed light on future designs of optimal robotic palpation.