Design and Application of a Novel Radio Frequency Wireless Sensor for Pre-Touch Sensing and Grasping of Objects

This article presents the design and experimental assessment of a novel sensing system for controlling the orientation of a robotic hand in grasping nonmetallic objects. This goal is pursued by using a radio frequency (RF) probe placed on the robotic hand and a printed resonator located on the tagged item. The real and imaginary parts of the probe input impedance are exploited to infer the angular orientation and distance between the object and the hand to help in finding the most suitable position for grasping. To assess the proposed design, a thorough experimental investigation has been carried out by using an ad hoc testing platform mimicking the robotic hand. Two different types of probes have been considered to obtain the proper coupling with the adopted U-shaped (hairpin) compact resonator. The set of performed measurements proves that the individuated RF system configuration allows the identification of the relative angular position of the probe and the distance between the probe and the resonator offering advantages compared to other approaches in terms of range and accuracy.