Miracle-dz/UniFAR-FTUs huggingface dataset:
On-Chip Test Clock Validation Using A Time-to-Digital Converter in FPGAs

While on-chip delay measurement combining logic BIST with a variable test clock is an effective way to secure field reliability of VLSI/FPGAs, validation of the variable test clock generated on the chip is important to guarantee measurement accuracy. This paper addresses a method of on-chip test clock validation using a TDC (Time-to-Digital Converter) for FPGAs. The proposed method has two operation modes, one is a resolution measurement mode and the other is a phase difference measurement mode. The resolution measurement mode is performed first to check the resolution of the TDC circuit. The phase difference measurement mode checks the timing difference between the original clock and the generated test clock. Evaluation experiments using a real FPGA device shows that the resolution of the proposed clock validation method using a TDC is 50.46 ps. For a variable test clock with resolution of 96.15 ps, it was confirmed that INL (Integral Non-Linearity) of the clock is within 10% and it was inconsistent with a result observed by an oscilloscope.
Kinematics Modeling and Gait Trajectory Tracking for Lower Limb Exoskeleton Robot based on PD Control with Gravity Compensation

Recently, the lower limb exoskeleton robot, which is a kind of wearable equipment, has been widely developed to help disabled people. To reduce the gait trajectory tracking errors of the lower limb exoskeleton robot during walking, a method of gravity compensation based on PD control was proposed in this paper. Firstly, the accurate kinematics model of two-link structure was established according to the Newton-Euler equations. Secondly, all parameters of the actual human-machine integrated robot system were identified and calculated by kinematics analysis. And then stability of the system with proposed controller was proved by Lyapunov stability theorem. At last, a simulation was presented based on MATLAB/Simulink platform. The simulation results show that the dynamics model is right and reliable, the gait trajectory tracking performance is excellent, and the controller can reduce the error of gait trajectory tracking to zero. The experiment demonstrated that the design of mechanical structure and control system was reasonable.
Variable Leg Stiffness Walking Control for the Biped Robot with Torso

The planar stable walking control of the biped robot with torso is studied in this paper. Firstly, improve the spring-mass model by adding a rigid torso to the hip joint and then get the spring-mass model with torso. Secondly, control the torque applied to the hip joint and regulate the stiffness of the springy leg to make the robot converge to the desired gait. Due to the nonlinear and strong coupling characteristics of the system model, use the feedback linearization to transform the nonlinear model into a linear model. Thirdly, the robot's torso angle and hip joint trajectory are controlled overall using PD control and P control. Finally, based on the theoretical analysis, the control method is simulated. The simulation results show that the feedback linearization and variable leg stiffness control methods used in this paper can achieve stable walking of the biped robot with torso, and have good anti-disturbance performance.
Physics-based Ankle Kinematics for Estimating Internal Parameters

This paper presents a kinematic model and its inverse solutions to identify internal ankle parameters in sagittal plane from external motion data; the effects of initial guesses and noise on the solutions are discussed. Experiments were designed to eliminate skin-marker errors in motion data, and performed to validate the model and the estimation method experimentally by comparing estimations with measurements from the computed tomography scan of the ankle. Based on observations that the skin temperature of bony prominences is lower than that of muscle, a novel infrared (markerless) method to locate bony prominences as features is conceptualized; experiments suggest that this concept feasibility is promising.
Electronically Beam-steerable Dual-band Reflectarray for Satellite Communications

This paper presents a novel continuously beam-steering dual-band, dual circularly polarized (CP) reflectarray. The dual band operation of the reflectarray is obtained by using the interleaved circularly polarized triangular patches as the radiating elements. Each of the patches has two proximity feed lines that are electromagnetically coupled to a branch line coupler, where the phase shifters are integrated. The phase shifter is realized by using a new type of high-frequency tunable dielectric materials, Lead Niobate Pyrochlores $Pb _{n} Nb _{2}O_{5+ {n}}\,($ PN). By controlling the applied voltage, the dielectric permittivity of the PN material can be changed. This characteristic is utilized to the design of tunable dielectric capacitors, which is placed between the ground and the signal line of a Co-planar waveguide (CPW) transmission line. To validate the design concept, X-band passive antenna prototype was designed, fabricated and measured. Preliminary results on the designed phase shifter and tunable dielectric materials are also presented in this paper.
Design of a New Wrist Rehabilitation Robot Based on Soft Fluidic Muscle

This paper presents the design of a new type of soft robot for wrist rehabilitation. The robot adopts six pneumatic fluidic muscles as flexible material-based actuators, which are evenly connected in parallel. The length control of the six actuators is realized via the regulation of air pressure, which enables the bending control of a wrist handle by internal and external rotation action. A larger bending angle of the handle is obtained by applying a larger air pressure. In addition, a stepper motor is used to drive the overall structure to achieve the stretching movement of the wrist. The proposed three-degree-offreedom wrist rehabilitation robot can drive the human wrist to bend, rotate, and stretch for rehabilitation. The designed rehabilitation robot is compact, flexible, safe and highly practical. It is suitable for recovering the patients with wrist rehabilitation.
Sub-Pixel Resolution Techniques for Ray Casting in Low-Resolution Occupancy Grid Maps

In robotics research, grid-based maps are widely used not only for localization and SLAM, but also as a prerequisite for navigational tasks such as path planning. Depending on the task, the utilized sensor, the chosen tradeoff between accuracy, runtime and memory requirements, and the exact map representation, a low grid resolution may be required. However, due to the involved discretization, occupancy grid maps suffer from aliasing effects and they are susceptible to sensor errors, especially if the resolution is low. In this work, we discuss different sub-pixel resolution methods, which improve the map quality without adapting the grid resolution. Therefore, we examine a grid traversal method inspired by antialiasing, which we use to apply weights to the grid cell updates in order to model straight beams more precisely. Further investigations include implicitly modeling the beam's width and shape. Finally, we inspect methods developed for ONDT maps and conduct extensive experiments to evaluate the discussed techniques.
A 3D Printed Soft Robotic Monolithic Unit for Haptic Feedback Devices

Stroke is a worldwide health problem causing loss of sensory and motor functions. Biofeedback plays a significant role in the rehabilitation process of stroke patients where various haptic feedback methods and devices are used. Such methods and devices can greatly improve the biofeedback provided during the rehabilitation process. This work proposes a soft monolithic haptic feedback device that can be directly manufactured using a low-cost additive manufacturing technology known as fused deposition modelling (FDM) that employ soft and flexible materials with low elastic moduli. A single unit of the soft haptic feedback device proposed was analyzed using finite element modeling (FEM). The experimental mechanical deformation and force output of the device are presented. A conductive resistive material was used to directly 3D print the sensory component of the device that provides force generated by the soft haptic feedback device when it is in direct contact with the human skin. A thermoplastic poly(urethane) (TPU) was employed to 3D print the actuation unit of the soft haptic feedback device.
Label-Free Optical Readout of Bacteria Density in Nanoliter Droplets

Droplet microfluidics is an important technique, used for antibiotic susceptibility testing and analysing bacteria at the single cell level. Optical screening methods allow for fast and reliable readout of bacteria density in droplets, however most of those optofluidic platforms are based on fluorescent light detection. This limits the applicability of the method only to genetically modified and labelled bacteria strains [1]. Here, we demonstrate a label-free readout of bacteria density in nanoliter droplets. This is achieved by detection of light scattered by bacteria inside the droplet. We demonstrate the we can differentiate empty droplets and the ones where bacteria proliferated. Additionally, we included a fluorescence detection path to verify our readout. The experiments are performed on the example of Escherichia coli proliferation.
Demonstration of a High Power Frequency-Tunable 0.22-THz Gyrotron Operating in High-Order Axial Modes

To explore the approach for generating high power frequency-tunable sub-THz to THz radiation, a 0.22-THz high-order axial modes (HOAMs) gyrotron is developed and tested in TRC-UESTC. The proof-of-principle experimental results demonstrate that a series of HOAMs in a long gyrotron cavity are excited successfully by an electron beam of high voltage and high current. A frequency tuning range of 0.79 GHz around 219 GHz has been achieved by tuning the operating magnetic field and operating in the first four axial modes. And during the frequency tuning, the out power kept no less than 0.45 kW, while the maximum output power was 3.80 kW. These experimental results of axial mode transition in high power sub-terahertz gyrotron should be conductive to the future development of frequency-tunable gyrotron towards some up-and-coming novel terahertz applications.
Substrate-enhanced THz nanoscopic recognition of single bacteria

We report on 600GHz nano imaging of single dried Pseudomonas fluorescens bacteria with a scattering-type THz nanoscope (THz-s-SNOM). A significant contrast enhancement due to an appropriate substrate like GaAs or gold instead of typically used microscope slides is theoretically expected and experimentally validated. This allows us to resolve the bacteria on a 130nm gold film, yielding the highest contrast. The acquired THz amplitude and phase images will further enable the quantitative analysis i.e. the determination of the dielectric properties of single bacteria not achieved at THz frequencies.
Ensemble Learning Based Multi-Color Space in Convolutional Neural Network

Convolutional neural networks is a common mean of accomplishing image classification tasks in recent years. The input of the existing networks are in single color space (RGB color space). In this paper, we propose an ensemble learning based multi-color space in the convolutional neural network, which can combine the advantages of multiple color spaces on the image. In addition, the color space conversion process can bring more nonlinear components to the network, which can increase the effectiveness of solving real-world classification tasks. Moreover, this article optimizes the method mentioned, so that the parameter quantity and calculation amount of the final network model is basically maintained at the original scale, and the accuracy rate is similarly improved. We conduct comparative experiments and show that ensemble learning based multi-color space in convolutional neural network achieves better performance than the original network.
The MERO Hand: A Mechanically Robust Anthropomorphic Prosthetic Hand using Novel Compliant Rolling Contact Joint *

Although substantial progresses have been made in building prosthetic hands, lack of mechanical robustness still restrains wide adoption of robotic hand prostheses. This paper presents the design and evaluation of the MERO hand, which is a MEchanically RObust anthropomorphic prosthetic hand using novel COmpliant Rolling-contact Element (CORE) joints. The proposed CORE joint, which has a simple structure, exhibits compliance in multiple directions. Its structural parameters were designed, to form underactuated finger designs that can perform adaptive finger motion during grasping. Experiments showed that the hand could withstand severe disarticulation and violent impact. The hand could perform various adaptive grasps and also in-hand manipulation, suggesting that the proposed design might be a viable solution for robust prosthetic hand.
Servo and Force Control with Improved Robustness and Accuracy for An Active Body Weight Support System

Active body weight support (ABWS) is of great importance for lower limb rehabilitation. We have built up an ABWS system to simultaneously follow the patient’s horizontal movement and provide the designed vertical body weight support force to the patient. However, the patient’s movement is highly dynamic and there exist disturbance and other uncertainties in the system, making it challenging for the position servo and force control. Two improved control strategies are respectively proposed, using disturbance observer (DOB) along with one-step prediction and dynamics compensation, to achieve accurate and robust horizontal position servo as well as vertical force control of the ABWS system. Experiments were conducted to verify the ef cacy of the proposed methods, and the results were signi cantly improved in comparison with PID control.
Narrow Linewidth InGaN Laser Diodes Based on External Cavity Fiber Bragg Grating

The first InGaN-based LDs were reported in 1996 by Nakamura and co-workers [1] and commercialized from 1999 by the Nichia Corporation. Since then, huge efforts have been devoted to the optimization of the epitaxial layers (doping, defect concentration, shortening of the radiative lifetime, etc.). Nowadays, blue laser diodes emitting hundreds of mW are commercially available but they often exhibit multimode behaviors for both transverse and longitudinal directions. The InGaN-based laser diode technology is still in its infancy, compared to its long wavelength counterparts and only recently the first electrically pumped single mode blue laser diodes have been demonstrated [2] with a resolution limited linewidth of 11.7 GHz. At telecom wavelengths, a mature approach to force the laser diode in a single frequency regime consists in using an external feedback by means of Fiber Bragg Grating [3,4]. Nevertheless, to our knowledge, such a compact design has not been proposed for blue laser diodes yet.
Microfabrication of Alkali Vapor Cells with Lower the Outgassing and Temperature Utilizing Silicon 3D Structure

We report an effective Cs vapor cell fabrication at the wafer-level utilizing a novel Cs-source, that are applicable to MEMS-based atomic clocks. In this method, a microfabricated Si grooves with multiple re-entrant structures (i.e., “micro-size” scalloped patterns) is employed as a preform, and CsN3 precursor is deposited on the surface. This method enables in-situ thermal decomposition of CsN3 with high efficiency at the wafer-level. The fabricated Cs-filled cells via a combination of the Cs-source and low-temperature bonding process achieved the good atomic clock frequency stability. Furthermore, the residual gas analysis data demonstrated that the Si preform enables low residual gasses in the cell, leading to enhance long-term stability of the Cs density.
Iterative Learning based Model Free Adaptive Control for Subway Trains with Speed and Input Constraints

In this paper, a partial form dynamic linearization based model free adaptive control (PFDL-MFAC) with iterative learning control (ILC) method is proposed for subway train speed tracking control subject to speed and input constraints by only using input output data of the subway train system. Firstly, under the speed and input constraints, a double loop controller structure is designed, which consists of ILC feedforward control loop and MFAC feedback control loop. It is a modular design method to realize the complementary advantages of MFAC and ILC. Secondly, for the influence of the time-iteration-dependent measurement disturbances on the subway train system, a robust controller design is also investigated. Furthermore, the speed and input constraints are never violated. Finally, the effectiveness of the designed control scheme is verified by a simulation of the subway train system.
Strategic Markowitz Portfolio Optimization (SMPO): A Portfolio Return Booster

In Financial Data Science and more specifically in Investment Analytics, Portfolio Optimization is a very crucial aspect. A portfolio consisting of a collection of securities, has certain weights assigned to each security. Banking on these weights, the overall Portfolio Return and Risk are determined. Investors always try to find the Optimized Portfolio by adjusting the weightage given to each security in the portfolio. In this paper, a diverse, practical and exemplar portfolio, also having tint of similarity among securities, is considered. It has stocks from 8 companies (not from or any particular market indices): General Motors (GM), Ford Motor Company (F), Cognizant (CTS), International Business Machines Corporation (IBM), Apple Technology Company (AAPL), Vivo (VIVO), Under Armour (UAA) and Nike (NKE). The Optimized Portfolio is constructed with adjusted weightage for each company in the portfolio using Strategic Markowitz Portfolio Optimization (SMPO). The obtained Optimized Portfolio yielded a Logarithmic Portfolio Return of 0.04268 at minimum Risk (Standard Deviation) of 0.14951 and maximum possible Logarithmic Return of 0.15873 at a Risk (Standard Deviation) of 0.17938. Using the Markowitz Portfolio Optimization in a strategic manner for such portfolio where there is diversity along with different shades of similarity, can fetch more Optimized Portfolio than obtained by the Classical approach of Markowitz Portfolio Optimization.
LIDAR-based model reconstruction for spacecraft pose determination

This paper deals with the problem of 3D surface reconstruction processing point clouds produced by a LIDAR. In the framework of an algorithmic architecture for pose determination of an uncooperative spacecraft, this functionality is required to update the existing model of the target geometry (reference model), if a non-negligible inconsistency with respect to its real geometry is detected. Hence, two original approaches to generate triangular mesh models from point clouds are developed, which are based on the marching-cube and Delaunay triangulation concepts, respectively. The output of these techniques can then be exploited within an original algorithmic strategy conceived to carry out the update function on the reference model, aiming at improving pose estimation accuracy. The two 3D surface reconstruction approaches are tested over point clouds acquired using a new prototype of the RVS 3000-3D® LIDAR produced by Jena-Optronik GmbH and a satellite mock-up as target. Their compatibility for real-time implementation on FPGA hardware is also preliminary evaluated. Finally, performance assessment of the proposed strategy for on-line update of the reference model is carried out within an ad-hoc experimental setup, using a Kinect V2 sensor to acquire point clouds of a scaled satellite mock-up.
Dynamic Service Selection in Backscatter-Assisted RF-Powered Cognitive Networks: An Evolutionary Game Approach

Conventional radio-frequency-powered cognitive networks can be combined with the backscatter communication technology to improve performance of the networks. In this paper, we consider a backscatter-assisted radio-frequency-powered cognitive network, where many secondary transmitters transmit data to a common secondary gateway. The secondary gateway, as a controller, provides two services for the secondary transmitters, and the secondary transmitters will adapt their service selection when their utilities are below the expected utility. To analyse the service selection of the secondary transmitters, we formulate the problem as an evolutionary game. Specifically, we model the service adaptation of the secondary transmitters by the replicator dynamics, and analytically prove that a unique evolutionary equilibrium is reached by the evolutionary game. Also, we prove that the evolutionary equilibrium is stable. We further present numerical results to provide insights of the dynamic service selection in the network.
Design and Analysis of Chipless RFID Tags Based on Retro-Radiators

Chipless RFID tag is a promising technique for future RFID systems due to its low cost and high reliability. In this paper, three chipless RFID tags are designed based on retro-reflective structures, in order to increase the reading range and enhance the tag’s robustness to the direction of the interrogating signals. The three tags include two linearly polarized tags with non-symmetric and symmetric filters and a circularly polarized tag. Before introducing the tag antennas, the design guidelines on how to arrange the filters for higher detection accuracy are provided based on standing wave analysis. Following the rules, retro-radiating tags with filters are designed. Since the $E$ fields from the retro-radiating antennas add constructively in the direction of the incoming signal automatically, the reading distance is greatly increased compared with the conventional tags with orthogonally placed antennas. The tag with symmetric filters and arrangements can further enhance the detection robustness regardless of the reader’s positions. Moreover, the circularly polarized tag is insensitive to the polarization of the incoming signals. The experimental results measured in the anechoic chamber show that the retro-radiator based tag can reach a reading distance of 60 cm, which is longer than most of the existing chipless tags. In the measurement, the proposed tag was well detected even when the reader antennas were not at the boresight.
Nanophotonic Hardware for Reservoir Computing — Spectrally Homogeneous Microlaser Arrays

Here we report on the fabrication and characterization of dense arrays of up to 900 microlasers for the implementation of a photonic hardware platform for reservoir computing [1, 2], a powerful concept of efficient neuromorphic data processing in which the input data gets transferred into a random and fixed recurrent network of coupled neural nodes. The network projects the input information into the high-dimensional reservoir space, which then can be processed simply by a trained readout system. This leads to interesting applications in the field of ultra-fast pattern recognition, or the prediction of chaotic temporal sequences [2]. To realize this interesting concept with nanophotonic nodes, we present a hardware platform based on a dense array of semiconductor micropillar lasers, which can be optically coupled and injected within a fully parallel concept. Our scheme is implemented by a diffractively multiplied external resonator, which redirects the emission of individual laser nodes in the array to their neighbouring nodes [3]. To enable this scheme the pitch of the laser array must be precisely adjusted, and most importantly their spectral homogeneity needs to be on the order of the emission linewidth of the cavity mode.