A Piezoelectric Tactile Sensor and Humaninspired Tactile Exploration Strategy for Lump Palpation in Teleoperative Robotic Minimally Invasive Surgery A piezoelectric tactile sensor is proposed in this paper featuring small size suitable for minimally invasive surgery (MIS), simple structure with only one transducer for both actuation and sensing, and easy instrumentation requiring only electrical impedance measurement. Its validity and sensing performance are confirmed with simulations. In addition, the sensor together with a model of soft tissue with embedded lump are used to generate stiffness maps in various scenarios, which facilitate the construction of a virtual lump palpation system together with a vibrotactile feedback device and a visual tracking system. Subsequent experimental studies reveal that human palpation strategies have influence on the lump detection performance. The Scanning strategy leads to better performance in lump localization and size discrimination ratio, whereas the Edge following strategy achieves better performance in shape discrimination. Therefore, a combination of different palpation strategies is suggested which may help achieve the best performance in all aspects of the lump palpation task, and finally forms a humaninspired lump palpation solution that contributes to the robotassisted MIS.

SemiAutonomous Interventional Manipulation using Pneumatically Attachable Flexible Rails During laparoscopic surgery, tissues frequently need to be retracted and mobilized for manipulation or visualisation. Stateoftheart robotic platforms for minimally invasive surgery (MIS) typically rely on rigid tools to interact with soft tissues. Such tools offer a very narrow contact surface thus applying relatively large forces that can lead to tissue damage, posing a risk for the success of the procedure and ultimately for the patient. In this paper, we show how the use of Pneumatically Attachable Flexible (PAF) rail, a vacuumbased soft attachment for laparoscopic applications, can reduce such risk by offering a larger contact surface between the tool and the tissue. Ex vivo experiments are presented investigating the short and longterm effects of different levels of vacuum pressure on the tissues surface. These experiments aim at evaluating the best tradeoff between applied pressure, potential damage, task duration and connection stability. A hybrid control system has been developed to perform and investigate the organ repositioning task using the proposed system. The task is only partially automated allowing the surgeon to be part of the control loop. A gradientbased planning algorithm is integrated with learning from teleoperation algorithm which allows the robot to improve the learned trajectory. The use of Similar Smooth Path Repositioning (SSPR) algorithm is proposed to improve a demonstrated trajectory based on a known cost function. The results obtained show that a smoother trajectory allows to decrease the minimum level of pressure needed to guarantee active suction during PAF positioning and placement.