USB Link Research Articles

Computer controlled image based object classification by using a robot manipulator

In this paper the design, implementation and application of a computer controlled vision system with a robot manipulator for classification of various fruits is introduced. The system, which consists of a RGB Camera, a PC and a five degree of freedom (DOF) robot manipulator, specifically set up to work in real-time applications. At the first stage of study the captured image of objects in RGB scale viewed by the camera is stored via USB link of computer as digital image data in registries for further segmentation process to recognize the objects. A particular Neural Network is designed to classify objects exactly. The moving objects on a belt, driven by a servo-stepper motor, are recognized in size and property via a vertically mounted camera. The recognized objects are then assorted by a computer controlled robot manipulator with five DOF and a gripper at the end-effecter, in order to transport the objects via a predefined trajectory to designated locations. As second stage, the kinematic link table of robot manipulator using inverse kinematics is determined, so that from the given way points of a particular trajectory the link parameters (joint angles) can be calculated. The joint angles are used as reference values for a joint based control algorithm programmed in C++. The joints are equipped with geared DC motors with position feedback. A particular control program is also used to control the motion of servo-stepper belt motor and the pneumatically activated gripper valve of the manipulator. Successful results are evaluated both in assorting of fruit in size, property, in synchronous working of the robot arm and in connection with image processing.

High Detection Rate Fast-Gated CMOS Single-Photon Avalanche Diode Module

We present a novel instrument for fast-gated operation of a 50 μm CMOS SPAD (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diode), driven by an integrated fast-gated active quenching circuit with transition times faster than 300 ps (20–80%). The instrument is based on a custom system-in-package where the SPAD and its driving electronics are housed in a TO-8 package. The detector can be operated at repetition rates up to 160 MHz, with gate on-times as short as 500 ps, always guaranteeing a temporal response with 60 ps (FWHM) timing jitter and short exponential decay (53 ps time-constant). A dark-count rate as low as 1 cps is achieved operating the CMOS SPAD at 5 V above breakdown at a temperature of 263 K, still keeping the afterpulsing probability lower than 2%, with only 50 ns hold-off time, thanks to the fast-gating driving electronics. The instrument is housed in a compact 5 × 4 × 8 cm3 case and can be triggered by either an external or internal source. A USB link allows to adjust measurement parameters, SPAD bias voltage and operating temperature. The high re-configurability of the instrument and its state-of-the-art performance make it suitable for applications where high detection rates and low timing jitter are required.

Human activity monitoring system based on wearable sEMG and accelerometer wireless sensor nodes

BackgroundThe human activity monitoring technology is one of the most important technologies for ambient assisted living, surveillance-based security, sport and fitness activities, healthcare of elderly people. The activity monitoring is performed in two steps: the acquisition of body signals and the classification of activities being performed. This paper presents a low-cost wearable wireless system specifically designed to acquire surface electromyography (sEMG) and accelerometer signals for monitoring the human activity when performing sport and fitness activities, as well as in healthcare applications.ResultsThe proposed system consists of several ultralight wireless sensing nodes that are able to acquire, process and efficiently transmit the motion-related (biological and accelerometer) body signals to one or more base stations through a 2.4 GHz radio link using an ad-hoc communication protocol designed on top of the IEEE 802.15.4 physical layer. A user interface software for viewing, recording, and analysing the data was implemented on a control personal computer that is connected through a USB link to the base stations. To demonstrate the capability of the system of detecting the user’s activity, data recorded from a few subjects were used to train and test an automatic classifier for recognizing the type of exercise being performed. The system was tested on four different exercises performed by three people, the automatic classifier achieved an overall accuracy of 85.7% combining the features extracted from acceleration and sEMG signals.ConclusionsA low cost wireless system for the acquisition of sEMG and accelerometer signals has been presented for healthcare and fitness applications. The system consists of wearable sensing nodes that wirelessly transmit the biological and accelerometer signals to one or more base stations. The signals so acquired will be combined and processed in order to detect, monitor and recognize human activities.

Wireless surface electromyograph and electrocardiograph system on 802.15.4

This paper presents a flexible low-cost wireless system specifically designed to acquire fitness metrics both from surface electromyographic (sEMG) and electrocardiographic (ECG) signals. The system, that can be easily extended to capture and process many other biological signals as well as the motion-related body signals, consists of several ultralight wireless sensing nodes that acquire, amplify, digitize, and transmit the biological or mechanical signals to one or more base stations through a 2.4 GHz radio link using a custom-made communication protocol designed on top of the IEEE 802.15.4 physical layer. The number of wireless nodes the base stations can handle depends on the type of signal being acquired. Each base station is connected through an USB link to a control PC running a user interface software for viewing, recording, and analyzing the data. The system for acquiring signals from wearable nodes in combination with a smartphone application provides a complete platform for monitoring fitness metrics extracted from the signals. 1

Hi-Speed USB Based Middleware for Integration of Real-Time Systems with the Cloud

An important aspect of realizations of the Internet of Things containing sophisticated sensors and actuators is their integration with the Cloud, by the use of a middleware. This integration results in handling streams of data produced by sensors as well as streams sent back to actuators. In cases for which both large streams and a short reaction time are required, a special real-time oriented approach is necessary to design and build an interconnecting middleware. This paper proposes a hybrid low-cost, low-power middleware architecture for handling and processing of sensor related data streams. It is based on two microprocessor boards interconnected by high speed USB link. Variants including three embedded hardware implementations of the proposed architecture, two software realizations (single and multithread ones), and two process scheduling algorithms have been examined to evaluate their real-time performances. Series of experiments have been performed in order to measure closed loop control times and sensor data streams achievable in practice. An outcome is presented and discussed in detail. Obtained results confirm that the proposed architecture can be applied as middleware to integrate such elements of Internet of Things as robots and similarly time-constrained systems with the Cloud. The results can serve as reference point in research and development of real-time middleware solutions.

Low-Cost and Compact Single-Photon Counter Based on a CMOS SPAD Smart Pixel

We present a single-photon counter based on a silicon single-photon avalanche diode (SPAD) fabricated in a 0.35-μm CMOS technology. The detector is monolithically integrated with a front-end circuit and a digital pulse output driver. External components are kept to a minimum, and the resulting instrument is low-cost, low-power, and compact, being housed into an industry-standard 1-in aluminum optical mounting tube. It features a maximum power consumption of just 250 mW from a USB link. The embedded 50-μm-diameter SPAD has high photon detection efficiency in the visible range (55% at 420 nm), low noise (<;100 Hz at room temperature), low timing jitter (<;100-ps full-width at half-maximum), and very low afterpulsing probability (down to 1% with 60-ns hold-off time). The high performance, compactness, and low cost enable many unexplored applications in life sciences, personal health care, industrial quality check, quantum physics and others, where it is required to count single photons and to measure their arrival time.

SYSTEM FOR MEASURING RODENTS' VISUAL FUNCTION: DESIGN AND IMPLEMENTATION

The aim of the work presented in this paper is the design, manufacturing and assembling of a system able to measure rodents' (mice and rats) visual function and to study the evolution of degenerative retina diseases. Measurement of contrast sensitivity and visual acuity is essential to design new drugs and understand mechanisms of visual development to evaluate treatments' effectiveness. Classical methods to study visual perception of animals such as electroretinogram (ERG) or histological analysis are not supplying enough information because connection between eyes and brain is not considered. The system proposed in this work consists of four screens forming a cube with black methacrylate plastic floor and roof. Screens display visual stimulus and the rodent's behaviour (placed over a platform in the middle of the cube) is analized to determine its visual acuity and contrast sensitivity. These visual stimuli are generated from a FPGA board designed in this project. This board has a USB link with a computer and it controls screens via VGA signals. Rodents' behaviour is analized using computer vision algorithms under OpenCV libraries. To test the system, more than 30 mice (C57 and RD10 type) have been used to validate the hardware, the software, the procedure and protocol.

Energy Efficient Output Regulation with Adaptive Behaviour in a DC-DC UPS

Abstract This paper presents an embeddable and highly customizable DC to DC UPS module in a novel and lightweight approach comparing to dozens of existing semi-industrial grade AC and DC UPS devices. Majority of them are following nearly the same, less flexible and less energy efficient scheme, operating on fixed battery type, fixed output voltage and having a featureless USB link to the host PC. In our vision energy efficiency is critical to achieve maximum performance at output without even moderate energy losses. This is even more important in case of an embeddable UPS device which needs to act as much “transparent” as it could in terms of energy efficiency reported to the primary energy source. This is mostly the main definition of our research area. Thus the main goal is to increase efficiency even with the cost of output precision but in the allowed domain of accepted input voltage range of the powered system. Our proposal, a combination of a mid range RISC MCU and a customizable AFE, power path controller and coulomb counter could result in a simpler but more efficient power converting device, even using low priced, less performing components (digital potentiometers and MOSFETs) where the control software could overcome many of the performance issues by algorithms.

Focus on semiconductors and software

Focus on semiconductors and software

Rapid Prototyping Methodology of Embedded Controlacquisition System

Abstract Modern control and measurement systems are equipped with interfaces to operate in local area networks and are typically intended to perform complicated data processing and control algorithms. The authors propose a digital system for rapid prototyping of target application devices. The concept solution separates the processing and control section from the hardware interface and user interface section. Both sections constitute independent ARM-based controllers interconnected via a direct USB link. Popular libraries can be used and low-level procedures developed, which enhances the system’s economic viability. A test unit developed for the purpose of the study was built around a SoC ARM7 microsystem and an off-the-shelf palmtop device. It demonstrated a continuous data stream transfer capability up to 150 kB per second, which was sufficient to monitor the performance of an electricity line.

10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB(rms). The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps(rms) (i.e., 36 ps(FWHM)) and in photon timing mode it is still better than 70 ps(FWHM). The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

Acquisition System and Detector Interface for Power Pulsed Detectors

A common DAQ system is being developed within the CALICE collaboration. It provides a flexible and scalable architecture based on giga-ethernet and 8b/10b serial links in order to transmit either slow control data, fast signals or read out data. A detector interface (DIF) is used to connect detectors to the DAQ system based on a single firmware shared among the collaboration but targeted on various physical implementations. The DIF allows to build, store and queue packets of data as well as to control the detectors providing USB and serial link connectivity. The overall architecture is foreseen to manage several hundreds of thousands channels.

Monolithic silicon matrix detector with 50 μm photon counting pixels

A 48-element monolithic matrix detector, designed for parallel fluorescence detection, has been fabricated in silicon and tested. The pixels are single photon avalanche diodes (SPADs) with 50 µm diameter, ordered in a 6× 8 array with 240 µm pitch. The photon detection efficiency is remarkably uniform over the array: it has a peak of 48% at 530 nm and it is higher than 30% over all the visible range. Low dark counting rate (DCR) is obtained in operation at moderately low temperature (−15°C with thermoelectric cooling): the individual pixel DCR is 60 c s−1 for about 40% of the elements and it is below 5700 c s−1 in the rest of the array. It was verified that the afterpulsing probability is below 1% and that the optical crosstalk probability between elements is lower than 0.2%. Based on this matrix detector, we have developed a versatile and compact (20 cm× 8 cm × 4 cm) photon counting module that can be easily interfaced to a PC via USB link.