Tactile Sensors for Parallel Grippers: Design and Characterization

Abstract

Tactile data perception is of paramount importance in today’s robotics applications. This paper describes the latest design of the tactile sensor developed in our laboratory. Both the hardware and firmware concepts are reported in detail in order to allow the research community the sensor reproduction, also according to their needs. The sensor is based on optoelectronic technology and the pad shape can be adapted to various robotics applications. A flat surface, as the one proposed in this paper, can be well exploited if the object sizes are smaller than the pad and/or the shape recognition is needed, while a domed pad can be used to manipulate bigger objects. Compared to the previous version, the novel tactile sensor has a larger sensing area and a more robust electronic, mechanical and software design that yields less noise and higher flexibility. The proposed design exploits standard PCB manufacturing processes and advanced but now commercial 3D printing processes for the realization of all components. A GitHub repository has been prepared with all files needed to allow the reproduction of the sensor for the interested reader. The whole sensor has been tested with a maximum load equal to 15N, by showing a sensitivity equal to 0.018V/N. Moreover, a complete and detailed characterization for the single taxel and the whole pad is reported to show the potentialities of the sensor also in terms of response time, repeatability, hysteresis and signal to noise ratio.

Proximity Sensor for Thin Wire Recognition and Manipulation

“…Starting from the tactile sensor developed and presented by the authors in [16,17], the pre-touch (proximity) sensor prototype described in this paper has been designed in order to be compatible with the existing tactile sensor solution from both mechanics and hardware/software points of view. In particular, the compatibility of the new sensors with the mentioned tactile one represented the principal design constraint, e.g., the new board has been designed in such a way it can be installed on the rear side of the tactile sensor and respecting the electrical and software interface of the latter.…”

“…If the reader is interested in having more details about the PC side-SW design and implementation, they can refer to [17].…”

“…Considering the good performance and the limited dimensions of the new off-theshelf ToF sensors, the authors believe that they represent the best enabling technology for pre-touch sensing. In particular, starting from the tactile sensors already developed by some of the authors in the last ten years [16,17], in this paper the authors present a new pre-touch sensing solution, fully integrated in the pre-existent tactile sensors, able to recognize the shape of the objects through a specific scanning procedure. The work focuses on Deformable Linear Objects (DLO) manipulation, which represents one of the main objectives of H2020 REMODEL project https://remodel-project.eu/ (accessed on 2 September 2021).…”

Tactile Sensor Data Interpretation for Estimation of Wire Features

“…The contact information is obtained from the deformation of this layer measured by the optical sensing points, here called "taxels". The main characteristics of the sensor, detailed in [22], are summarized in Table 1. The electronic part of the tactile sensor consists of two PCBs: one with optoelectronicbased taxels and one for power supply management and external communication.…”

“…Section 2 briefly recalls main features of the tactile sensor used in this paper. The interested reader can find a detailed characterization of the technology in [22]. Section 2 proposes a new optimized algorithm to estimate the shape of the grasped wire, by improving the estimation quality with respect to the solution presented by the authors in [23].…”