A Variable-Impedance Tactile Sensor with Online Performance Tuning for Tissue Hardness Palpation in Robot-Assisted Minimally Invasive Surgery

This paper presents a novel tactile sensor whose sensing performance (sensitivity, range, etc.) can be tuned online by varying its mechanical impedance with a double-cantilever structure. Therefore, it can solve the problems of narrow sensing range and non-optimal sensitivity faced by existing dynamic tactile sensors. The sensor is driven by a piezoelectric patch which acts simultaneously as both the actuator to generate vibration and the sensor to detect resonance from its electrical impedance. Its basic working principle and the variable-impedance method for performance tuning are explained mathematically and verified by numerical simulations and experimental studies. The proposed variable-impedance methodology can inspire the designs of a new class of tactile sensors for applications in robotics, biomedical engineering, aerospace, etc.