Davide Cattin

Towards Tactile Sensing System on Chip for Robotic Applications

This paper presents the research on tactile sensing system on chip. The tactile sensing chips comprise of 5 × 5 array of Piezoelectric Oxide Semiconductor Field Effect Transistor (POSFET) devices and temperature sensors. The POSFET devices are obtained by spin coating piezoelectric polymer, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), films directly on to the gate area of Metal Oxide Semiconductor (MOS) transistors. The tactile sensing chips are able to measure dynamic contact forces and temperatures. The readout and the data acquisition system to acquire the tactile signals are also presented. The chips have been extensively tested over wide range of dynamic contact forces and temperatures and the experimental results are presented. The paper also reports the research on tactile sensing chips with POSFET array and the integrated electronics.

Development and characterization of touch sensing devices for robotic applications

This paper presents the development of touch sensing chips for robotic applications and the experimental results from touch sensing elements on the chip. The high resolution tactile sensing chips have overall dimension of 1.5 cm×1.5 cm and consist of 25 touch sensing elements. The touch sensing elements on the chip are the POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices, obtained by depositing piezoelectric polymer directly on to the gate area of MOS transistor. Each sensing element has an effective sensing area of 0.5 mm×0.5 mm. The tactile sensing chips are suitable for fingertips of a robot where large numbers of sensors are needed in a small space (typically 1 cm×1.5 cm). The tactile sensing elements on the chip have been experimentally evaluated in time and frequency domain. Typically, protective rubber films of materials like PDMS Polydimethylsiloxane) are used to improve robustness of the sensors, albeit, at the cost of reduced sensitivity. Such effects on the response of POSFET touch sensing elements are studied with PDMS films having different thicknesses.

POSFET touch sensor with on-chip electronic module for signal conditioning

This paper presents the design, fabrication and evaluation of the new version of POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) touch sensing device based tactile sensing chip. Implemented using CMOS (Complementary Metal Oxide Semiconductor) technology, the chip consists of POSFET device and the integrated bias (a high compliance current sink) circuitry. The high compliance current sink provides the current IDS for the POSFET devices. The performance of tactile sensing chip has been evaluated in the dynamic contact forces range of 0.01–3 N and the sensitivity of POSFET devices (without amplification) is 102.4 mV/N.

Identification and validation of a fractional order dynamic model for a piezoelectric tactile sensor

This paper presents the identification of a piezoelectric tactile sensor which aims to give the sense of touch to humanoid robots. The sensor has been characterized in frequency domain and the low frequency behavior reveals a non-integer behavior. A simple model based on the a priori knowledge of the sensor and the observation of the frequency response has been hypothesized and a least squares method has been applied to identify the device. The impulse response has been calculated using the Mittag-Leffler function and validation in time domain has been performed. Simulation and experimental results are in good agreement showing that the identified model, despite its simplicity, is able to represent properly the tactile sensor.

Tactile Sensing Systems Based on POSFET Sensing Arrays

This work presents current research achievements on POSFET sensing arrays based tactile sensing system. The tactile sensing chips implement POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices arrays and temperature sensors. This work presents quantitative evaluation of the tactile sensing chip and a proposal for the electronic data acquisition system. Our goal is to integrate the POSFET arrays into the hands of humanoid robots.

A PhysX-based framework to develop rehabilitation using haptic and virtual reality

The use of virtual reality with haptic interactions seems quite promising for rehabilitation procedure as it provides several advantages: it is possible to change the experiments in the real world based on the patient disability, to use different devices depending on the target of the rehabilitation, and to record quantitative information during the execution of the training session. To cope with the required flexibility and adaptability, we developed a software framework based on the Model/View/Controller pattern that allows to decouple the different modules composing the application. To reduce the cost, the framework is implemented only through the use of freely available libraries. The efficacy of the framework was proved through the implementation of the software for a prototype application based on a five-bar linkage haptic device.

Identification and validation of a lumped parameters model for the dielectric relaxation of a piezoelectric tactile sensor

This paper presents the identification of a lumped parameters model of a POSFET tactile sensor which aims to give the sense of touch to humanoid robots. A Cole-Cole model has been design in order to describe the dynamic of dielectric relaxation of the PVDF-TrFE piezoelectric polymer. The tactile sensor has been characterized in time and frequency domain. The parameters of the model have been estimated from the time domain response and validated in frequency domain.