Proximity Sensor for Thin Wire Recognition and Manipulation

Abstract

In robotic grasping and manipulation, the knowledge of a precise object pose represents a key issue. The point acquires even more importance when the objects and, then, the grasping areas become smaller. This is the case of Deformable Linear Object manipulation application where the robot shall autonomously work with thin wires which pose and shape estimation could become difficult given the limited object size and possible occlusion conditions. In such applications, a vision-based system could not be enough to obtain accurate pose and shape estimation. In this work the authors propose a Time-of-Flight pre-touch sensor, integrated with a previously designed tactile sensor, for an accurate estimation of thin wire pose and shape. The paper presents the design and the characterization of the proposed sensor. Moreover, a specific object scanning and shape detection algorithm is presented. Experimental results support the proposed methodology, showing good performance. Hardware design and software applications are freely accessible to the reader.

Wire Grasping by Using Proximity and Tactile Sensors

“…Figure 1 on left reports a picture where the main PCB and 3 ToF sensors are highlighted. Additional details both from hardware and software point of view can be found in [14].…”

“…Such information can be then used to compute a suitable grasping pose for the robot's end effector. The scanning strategy is an optimized version of the one proposed in [14], where the trajectory is computed offline from user defined parameters and the corresponding area is scanned entirely. The pseudo-code of the scanning strategy is reported in Algorithm 1.…”

“…4). The main difference between the strategy proposed in [14] and the one explained above is that in this optimized version, when the wire is detected, the scanning trajectory is updated online in order to scan only a small area nearby the wire. By using the original strategy, instead, the robot scans the whole area defined offline by ∆x and ∆y (see Fig.…”

“…Optical proximity sensors based on Time-of-Flight (ToF) technology represent a solution to overcome some of the mentioned issues. ToF sensors do not need calibration and they are robust and accurate enough with a wide range of materials and in the execution of several different tasks [1], [12]- [14]. For the sake of completeness, the authors would remark that proximity sensors can provide relevant data also in safety critical situations, e.g., Human-Robot Collaboration tasks [15], [16].…”

“…Considering the good performance and the limited dimensions of the new off-the-shelf ToF sensors, the authors of this paper presented in [14] a new pre-touch sensing solution, fully integrated in the pre-existent tactile sensors developed by some of the authors in the last ten years [17], [18]. The main objective is the manipulation of Deformable Linear Objects (DLOs), e.g., thin electrical wires, within the activities of H2020 REMODEL project 1 .…”