Behavioral Characteristics of Manual Palpation to Localize Hard Nodules in Soft Tissues

Abstract

Abstract-Improving the effectiveness of artificial tactile sensors for soft tissue examination and tumor localization is a pressing need in robot-assisted minimally invasive surgery. Despite the availability of tactile probes, guidelines for optimal examination behaviors that best exploit soft tissue properties are not available as yet. Simulations on soft-tissue palpation show that particular stress-velocity patterns of probing lead to constructive dynamic interactions between the probe and the tissue to localize hard nodules. However, there has been no methodical validation of such probing behavioral hypotheses using human participants so far. In this study, we use simulation studies to establish open hypotheses on the interaction and influence of relevant behavioral palpation variables, such as finger velocity and trajectory, force exerted by fingers on the accuracy of detection of embedded nodules. We test them by analyzing palpation strategies used by humans to detect hard nodules inside silicone phantoms and ex-vivo porcine organs. Our findings allow us, for the first time, to derive palpation behavior guidelines suitable for the design of controllers of palpation robots.

Can a Soft Robotic Probe Use Stiffness Control Like a Human Finger to Improve Efficacy of Haptic Perception?

“…However, detecting the nodule at deeper depth is beyond the scope of this paper. In addition, our previous work shows [11] that humans regulate force and velocity during manual palpation. Therefore, it would be interesting to add such behavioral variation on top of the stiffness control to study the interaction between the stiffness and behavior.…”

“…This way, humans can build associations between haptic information with the behavioral variables to estimate the physical property of the environment [8]- [10]. For example, our recent study [11] shows that humans use different force/velocity control strategies during manual palpation to detect abnormality inside a soft silicon phantom. The regulation of these strategies are accompanied by behavioral variations like movement of fingers in different trajectories, velocities, frequencies, regulation of finger's joint stiffness, and regulation of applied pressure and force at the finger tip [12].…”

Visual and tactile feedback for a direct‐manipulating tactile sensor in laparoscopic palpation

“…The sensory feedback for tumor detection also affects the movement in manipulation. In manual palpation, humans use complex modulation strategies of contact force and scanning speed . These studies imply that humans change their motor control appropriately according to the sensory information and the current sensing environment.…”

Autonomous robotic palpation of soft tissue using the modulation of applied force

“…The previous studies conducted by authors [12], [13] highlight the importance of an appropriate probing behavior applied during tactile examination. Therefore, there is a strong need to develop not only tactile devices to measure tissue stiffness, but also algorithms and control methods that can be used to enhance tactile perception.…”