Daniele Comotti

Development of a wireless low-power multi-sensor network for motion tracking applications

This work presents a novel wireless and low power Attitude and Heading Reference Systems network based on low-cost MEMS (Micro Electro-Mechanical System) sensors, developed for motion tracking systems. Biomedical and rehabilitation purposes as well as gaming and consumer electronics may be the potential applications of this network. The paper aims to describe the hardware architecture, the embedded sensor fusion algorithm and the motion tracking system.

A Novel Body Sensor Network for Parkinson's Disease Patients Rehabilitation Assessment

A miniaturized wireless Attitude and Heading Reference System has been developed with the primary purpose to achieve a body sensor network for motor performance quantitative analysis of Parkinsons disease patients during rehabilitation sessions. The paper describes the performance of the single node, the peculiarities of the developed wearable network and the custom software developed specifically for the Extended Timed-Up-and-Go test. An experimental protocol on Parkinsons Disease patients is currently ongoing. This paper reports the preliminary results, involving 13 patients (mean age 64.6±9) with a moderate disease level and 4 controls (mean age 64.3±4). The data taken during rehabilitation exercise have been analyzed and outcomes are discussed.

neMEMSi: One step forward in wireless attitude and heading reference systems

This work presents neMEMSi, a novel MEMS based inertial and magnetic system-on-board with embedded processing and wireless communication capabilities, providing an ultra low-power and easy to use Attitude and Heading Reference System (AHRS). Main target applications are navigation systems and inertial based motion tracking technologies. The paper describes the architecture of neMEMSi and provides an evaluation of the performance in terms of key features of state-of-the-art AHRS.

The DSSC pixel readout ASIC with amplitude digitization and local storage for DEPFET sensor matrices at the European XFEL

The DSSC (DEPFET Sensor with Signal Compression) consortium develops a IMPixel detector for low energy X-rays at the European XFEL. The XFEL will produce 10 bursts per second, each containing 2880 X-ray pulses with a repetition rate of 4.5 MHz. X-ray photons of 0.5 - 6 keV are absorbed in hexagonal DEPFET pixels of 229 × 204 μm2 pitch with a nonlinear characteristic to achieve a high dynamic range. The sensors will be bump bonded to readout ASICs of 64 × 64 pixels. Each pixel contains a filter with trapezoidal weighting function, a single slope ADC of 8-9 Bit resolution and a digital memory to store 640 events. A veto mechanism allows to discard uninteresting events. The digital hit data is read out serially during the ≈100 ms long burst gaps. Prototype matrix chips of 8 × 8 pixels with the full functionality have been produced and characterized electronically and with DEPFET sensors. The architecture and the design of the 8 × 8 ASIC, measured results and an outlook to the large 64 × 64 pixel chip will be presented.

The PixFEL project: development of advanced X-ray pixel detectors for application at future FEL facilities

The PixFEL project aims to develop an advanced X-ray camera for imaging suited for the demanding requirements of next generation free electron laser (FEL) facilities. New technologies can be deployed to boost the performance of imaging detectors as well as future pixel devices for tracking. In the first phase of the PixFEL project, approved by the INFN, the focus will be on the development of the microelectronic building blocks, carried out with a 65 nm CMOS technology, implementing a low noise analog front-end channel with high dynamic range and compression features, a low power ADC and high density memory. At the same time PixFEL will investigate and implement some of the enabling technologies to assembly a seamless large area X-ray camera composed by a matrix of multilayer four-side buttable tiles. A pixel matrix with active edge will be developed to minimize the dead area of the sensor layer. Vertical interconnection of two CMOS tiers will be explored to build a four-side buttable readout chip with small pixel pitch and all the on-board required functionalities. The ambitious target requirements of the new pixel device are: single photon resolution, 1 to 104 photons @ 1 keV to 10 keV input dynamic range, 10-bit analog to digital conversion up to 5 MHz, 1 kevent in-pixel memory and 100 μm pixel pitch. The long term goal of PixFEL will be the development of a versatile X-ray camera to be operated either in burst mode (European XFEL), or in continuous mode to cope with the high frame rates foreseen for the upgrade phase of the LCLS-II at SLAC.

A java vs. c++ performance evaluation: a 3d modeling benchmark

Along the years robotics software and applications have been typically implemented in compiled languages, such as C and C++, rather than interpreted languages, like Java. This choice has been due to their well-known faster behaviors, which meet the high performance requirements of robotics. Nevertheless, several projects that implement robotics functionality in Java can be found in literature and different experiments conduced by computer scientists have proved that the difference between Java and C++ is not so evident. In this paper we report our work on quantifying the difference of performance between Java and C++ and we offer a set of data in order to better understand whether the performance of Java allows to consider it a valid alternative for robotics applications or not. We report about the execution time of a Java implementation of an algorithm originally written in C++ and we compare this data with the performance of the original version. Results show that, using the appropriate optimizations, Java is from 1.09 to 1.51 times slower than C++ under Windows and from 1.21 to 1.91 times under Linux.

Dynamic Compression of the Signal in a Charge Sensitive Amplifier: From Concept to Design

This work is concerned with the design of a low-noise Charge Sensitive Amplifier featuring a dynamic signal compression based on the non-linear features of an inversion-mode MOS capacitor. These features make the device suitable for applications where a non-linear characteristic of the front-end is required, such as in imaging instrumentation for free electron laser experiments. The aim of the paper is to discuss a methodology for the proper design of the feedback network enabling the dynamic signal compression. Starting from this compression solution, the design of a low-noise Charge Sensitive Amplifier is also discussed. The study has been carried out by referring to a 65 nm CMOS technology.

Novel active signal compression in low-noise analog readout at future X-ray FEL facilities

This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 μm. This work has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare (INFN), Italy.

Design and TCAD simulations of planar active-edge pixel sensors for future XFEL applications

We report on the design and TCAD simulations of planar active-edge pixel sensors within the INFN PixFEL project. These devices are intended as one of the building blocks for the assembly of a multilayer, four-side buttable tile for X-ray imaging applications in future Free Electron Laser facilities. The requirements in terms of very wide dynamic range and tolerance to extremely high ionizing radiation doses call for high operation voltages. A comprehensive TCAD simulation study is presented, aimed at the best trade-offs between the minimization of the edge region size and the sensor breakdown voltage.

Application of a wireless BSN for gait and balance assessment in the elderly

In developed countries, sedentary lifestyle is a major health risk factor. In elderly people, such mobility limitation is worsened by the reduced self-confidence and the fear of falling, leading to a further motor deterioration. This work presents an application of a wireless Body Sensor Network as a simple and easy-to-use individual motor function assessment tool for elderly. The wearable nodes have been exploited to monitor the body during the Six-Minute Walk Test and a set of stability tests. During the exercises, wearable sensors inertial data, along with the real-time orientation of the platforms, have been exploited to obtain gold-standard indicators (such as total distance) and some additional gait parameters. Stability tests consist of a series of single and double stance exercises aimed to assess the balance of the subject. This paper presents the system, the processing and the preliminary results on two subjects groups of different ages (31±6 and 70.8±7).