Input Angle Research Articles

Development of 18 DOF Salamander Robot Using CPG Based Locomotion for Straight Forward Walk

The utilization of mechatronics, robotics, and control systems has been widely spread in many areas over the last few decades. Robotics research is widely used for industrial purposes such as wheeled robots and manipulators, but nowadays many researchers have incorporated biomimetic science, often called biorobotics. This paper presents a preliminary research in the field of biorobotics with a robot salamander model that can walk in straight walking using a central pattern generator (CPG). This robot model uses a legged locomotion system that has 18 degrees of freedom (DOF). The CPG based locomotion model is developed for controlling the gait cycle when the robot walks. The motions of joint angle inputs resulted from CPG model is simulated using SimMechanics 3D Animation and implemented on the proposed salamander robot for straight walking. Based on the result in both virtual reality simulation and experimental work using CPG locomotion approach, the predefined joint angle inputs in salamander robot can be used to drive the robot. The proposed CPG locomotion can mimic the walking of a real salamander naturally in straight walk.

Geometric Flow Control Lateral Flow Immunoassay Devices (GFC-LFIDs): A New Dimension to Enhance Analytical Performance.

The nitrocellulose (NC) membrane based lateral flow immunoassay device (LFID) is one of the most important and widely used biosensor platforms for point-of-care (PoC) diagnostics. However, the analytical performance of LFID has limitations and its optimization is restricted to the bioassay chemistry, the membrane porosity, and the choice of biolabel system. These bottom neck technical issues resulted from the fact that the conventional LFID design principle has not evolved for many years, which limited the LFID for advanced biosensor applications. Here we introduce a new dimension for LFID design and optimization based on geometric flow control (GFC) of NC membranes, leading to highly sensitive GFC-LFID. This novel approach enables comprehensive flow control via different membrane geometric features such as the width (w) and the length (l) of a constriction, as well as its input angle (θ1) and output angle (θ2). The GFC-LFID (w=0.5 mm, l=7 mm, θ1= 60°, θ2= 45°) attained a 10-fold increase in sensitivity for detection of interleukin-6 (IL-6), compared with conventional LFID, whereas reducing by 10-fold the antibody consumption. The GFC-LFID detects IL-6 over a linear range of 0.1–10 ng/mL with a limit of detection (LoD) of 29 pg/mL, which even outperforms some commercial IL-6 LFIDs. Such significant improvement is attained by pure geometric control of the NC membrane, without additives, that only relaying on a simple high throughput laser ablation procedure suitable for integration on regular large-scale manufacturing of GFC-LFIDs. Our new development on GFC-LFID with the combination of facile scalable fabrication process, tailored flow control, improved analytical performance, and reduced antibodies consumption is likely to have a significant impact on new design concept for the LFID industry.

Unknown-input observer for vehicle lateral dynamics using new sensor force technology

Robust estimation of important states for vehicles (steering angle and sideslip angle) is essential for vehicle handling and stability control. In the past, the estimation of vehicle lateral state with the measured steering angle has been proposed. In this paper, four unknown input observers are designed using lateral tyre force measurements based on a nonlinear vehicle model, to simultaneously estimate vehicle steering angle as unknown input and vehicle lateral state variables sideslip angle and yaw rate. All of the design conditions are formulated in terms of linear matrix inequalities (LMI) which can be solved efficiently. Simulation results through MATLAB/Simulink software based on data of the CALLAS vehicle simulator are used to evaluate the performance of observers based on nonlinear unknown input observer (ONEI).

Optimization of Output Voltage of Switched Reluctance Generator Based on Improved Fuzzy Control

This paper takes the output of the switched reluctance generator as the research object and analyzes the main factors affecting the output voltage ripple. In order to optimize the output voltage of the switched reluctance generator at high speed, This paper proposes an angle position control strategy based on improved fuzzy control. When the load changes, the initial value of the turn-on angle of the fuzzy control adjustment is adaptively identified. Adaptive value of turn-off angle input to the system. This method quickly and accurately changes the conduction angle so that the output voltage is optimized. The simulation results show that compared with the fuzzy control, the improved fuzzy control strategy can effectively optimize the output voltage and reduce the voltage ripple.

Dynamic responses and damage forms analysis of underground large scale frame structures under oblique SV seismic waves

This paper mainly focuses on distinctive dynamic responses of the underground large scale frame structure (ULSFS) under obliquely asynchronous seismic inputs of the near-fault ground motion. To achieve the arbitrarily oblique input of seismic waves, the ground motions are transformed into equivalent forces adding on the 3-D viscous-spring artificial boundary nodes based on the theory of wave propagation. The ULSFS with great scales along two horizontal directions are proposed according to a well-designed underground market under construction. The dynamic responses of the ULSFS under different oblique incident angles of seismic waves are compared. The failure mechanisms of the ULSFS are explored by the tensile damage of floor slabs and walls, and stresses and strains of frame columns. The results demonstrate that dynamic responses of the ULSFS with two horizontal great scales would be sensitive to oblique incident angles of the seismic input; and the ULSFS is more likely to be compression-shear failure under the combination of the asynchronous horizontal and vertical seismic waves.

Yaw and Lateral Stability Control for Four-Wheel Steer-by-Wire System

A four-wheel steer-by-wire vehicle (FSV), which is a combination of a steer-by-wire (SBW) system and a four wheel steering (4WS) system, not only can improve vehicle safety and maneuverability, but also steering flexibility. Considering the parameters, uncertainties of vehicle speed, and tire cornering stiffness, weighted function is solved to express the uncertain system. Aiming at the multiple-input multiple-output (MIMO) system, the structured singular value $\mu $ is used to research FSV under multiple perturbations in this paper. Based on $\mu $ control strategy, $\mu $ controller is designed to track the desired sideslip angle and yaw rate. Thus, the vehicle gets better performance. Compared with SBW and 4WS systems, FSV has better state response under steering angle step input simulation experiment. The advantages of $\mu $ control compared with $H$ ∞ control on FSV have been explained in the simulation experiments. Furthermore, experiment results show that the designed controller can make the vehicle well track the reference model and improve the vehicle maneuverability.

A computational model of internal representations of chemical gradients in environments for chemotaxis of Caenorhabditis elegans

The small roundworm Caenorhabditis elegans employs two strategies, termed pirouette and weathervane, which are closely related to the internal representation of chemical gradients parallel and perpendicular to the travelling direction, respectively, to perform chemotaxis. These gradients must be calculated from the chemical information obtained at a single point, because the sensory neurons are located close to each other at the nose tip. To formulate the relationship between this sensory input and internal representations of the chemical gradient, this study proposes a simple computational model derived from the directional decomposition of the chemical concentration at the nose tip that can generate internal representations of the chemical gradient. The ability of the computational model was verified by using a chemotaxis simulator that can simulate the body motions of pirouette and weathervane, which confirmed that the computational model enables the conversion of the sensory input and head-bending angles into both types of gradients with high correlations of approximately r > 0.90 (p < 0.01) with the true gradients. In addition, the chemotaxis index of the model was 0.64, which is slightly higher than that in the actual animal (0.57). In addition, simulation using a connectome-based neural network model confirmed that the proposed computational model is implementable in the actual network structure.

Experimental study on effect of wick structures on thermal performance enhancement of cylindrical heat pipes

The effect of varying wick structures viz. mesh, sintered and composite wick (sintered-mesh) on the thermal enhancement of cylindrical heat pipes is experimentally investigated. In addition, the investigation focused on the effect of inclination angle and heat input of heat pipe. Surfactant free CuO nano-fluid with a mass concentration of 1.0% is used as a working fluid. The energy and exergy analysis of heat pipe was also conducted at various conditions. To analyze the distinctive performance of composite heat pipe, a heat pipe is filled with DI water and the obtained results are compared with nanofluid results. The maximum heat transfer capability of composite heat pipe is improved by 35.71% and 18.75% compared with mesh and sintered wicks. The composite heat pipe with CuO nanofluid as working fluid instead of DI water improves the heat transport capacity by 11.76%. Surface temperature of heat pipe significantly reduces by varying the wick structure viz. mesh, sintered and composite wick. The composite heat pipe with 1.0 mass% of CuO nanofluid obtained 3.7 °C reduction in surface temperature at evaporator section compared with DI water. Thermal resistance of heat pipe is gradually reduces with increasing inclination angle. The maximum reduction is observed for composite wick, sintered and mesh wick heat pipes are 47.50, 43.70 and 24.39% respectively at 45° inclination angle compared with horizontal axis.

Comprehensive Evaluation of Regional Sustainable Development Based on Data Envelopment Analysis

In the light of the shortcomings of the analytic hierarchy process and other common regional sustainable development evaluation methods, this paper proposes the use of a combination of subjective and objective weights to generate input/output indicators using the Data Envelopment Analysis (DEA) method. Using this methodology, we construct a comprehensive evaluation index which is useful in expanding the application of Data Envelopment Analysis (DEA) in the comprehensive evaluation of sustainable development. Moreover, this paper addresses the shortfalls of the traditional DEA evaluation model and uses the Super-Slack Based Measure (SBM)-Undesirable and DEA-Malmquist evaluation models, which are based on traditional DEA model optimization, to analyze the spatio-temporal characteristics of sustainable development on regional scales. Using China’s Yangzte River Economic Belt as an example, an empirical analysis is carried out. We show that analysis results are virtually identical to the extant situation and can objectively reflect the status and abilities of sustainable development in each subregion. Additionally, from the angles of input, output and technological progress, this paper uses the DEA evaluation method to analyze the reasons behind the slow development in several provinces and municipalities along the Yangzte River Economic Belt (YERB). The regional characteristics of each province and city within our study are combined to explore the optimal mechanisms for sustainable development.

Metasurface-based multi-harmonic free-electron light source

Metasurfaces are subwavelength spatial variations in geometry and material where the structures are of negligible thickness compared to the wavelength of light and are optimized for far-field applications, such as controlling the wavefronts of electromagnetic waves. Here, we investigate the potential of the metasurface near-field profile, generated by an incident few-cycle pulse laser, to facilitate the generation of high-frequency light from free electrons. In particular, the metasurface near-field contains higher-order spatial harmonics that can be leveraged to generate multiple higher-harmonic X-ray frequency peaks. We show that the X-ray spectral profile can be arbitrarily shaped by controlling the metasurface geometry, the electron energy, and the incidence angle of the laser input. Using ab initio simulations, we predict bright and monoenergetic X-rays, achieving energies of 30 keV (with harmonics spaced by 3 keV) from 5-MeV electrons using 3.4-eV plasmon polaritons on a metasurface with a period of 85 nm. As an example, we present the design of a four-color X-ray source, a potential candidate for tabletop multicolor hard X-ray spectroscopy. Our developments could help pave the way for compact multi-harmonic sources of high-energy photons, which have potential applications in industry, medicine, and the fundamental sciences.

Analysis of Handling Stability of Hydraulic Hybrid Vehicle based on ADAMS/Car Simulation

Hydraulic hybrid vehicle is developed from the traditional vehicle by installation of the hydraulic system and disassembly of the mechanical transmission system, which influences the handling stability by changes of the centroid. Three layout schemes of the hydraulic system in hydraulic hybrid vehicle were proposed in this study, which were based on available space of the vehicle and size of the major hydraulic component. According to virtual prototype model of the vehicle constructed in ADAMS/Car software, simulations of the three layout schemes on steering angle step input test, steering angle pulse test and snake formation test were conducted. Scores of the steering angle step input test, steering angle pulse test and snake formation test of the T-type layout were 82, 80.72 and 93.42. Meanwhile, these of the postposition layout were 76, 79.46, and 91.11, and these of the parallel layout were 86, 82.19 and 95.55. Therefore, the final scores of these three layout schemes were 256.14, 246.57, and 263.74, respectively. Simulation results indicated that the parallel layout exhibited the best handling stability, which would be propitious to improve comprehensive performance of the hydraulic hybrid vehicle.

Robust H2 optimal depth control of an autonomous underwater vehicle with output disturbances and time delay

This paper proposes a robust H2 optimal control strategy for the depth-plane motion of an autonomous underwater vehicle (AUV) in the presence of output disturbances and time delay. The six degrees of freedom nonlinear kinematic and dynamic equations of motion of the vehicle are firstly described. The depth-plane linearization of the vehicle equations of motion is then derived for efficient controller design from the practical point of view. Using this linearized and reduced-order model, a robust H2 optimal control method is designed. The designed control method takes into account both the output disturbances and time delay and provides suitable control action for desired tracking. The robust stability and robust performance of the proposed control method with respect to the model uncertainties are discussed. Simulation studies demonstrate that the proposed robust H2 optimal control strategy has remarkable performance and provides higher tracking accuracy, better output disturbances rejection ability, stronger robustness against model uncertainties, and smaller fin angle input than the existing pitch-and-depth loop PD depth controller.

Motion Cycle and Configuration Torus With Their Relationship to Furcation During Reconfiguration

In a classical mobility-one single loop linkage, the motion begins from an original position determined by the assembled condition and runs in cycles. In normal circumstances, the linkage experiences a full cycle when the input-joint completes a full revolution. However, there are some linkages that accomplish a whole cycle with the input-joint having to go through multiple revolutions. Their motion cycle covers multiple revolutions of the input-joint. This paper investigates this typical phenomenon that the output angle is in a different motion cycle of the input angle that we coin this as the multiple input-joint revolution cycle. The paper then presents the configuration torus for presenting the motion cycle and reveals both bifurcation and double points of the linkage, using these mathematics-termed curve characteristics for the first time in mechanism analysis. The paper examines the motion cycle of the Bennett plano-spherical hybrid linkage that covers an 8π range of an input-joint revolution, reveals its four double points in the kinematic curve, and presents two motion branches in the configuration torus where double points give bifurcations of the linkage. The paper further examines the Myard plane-symmetric 5R linkage with its motion cycle covering a 4π range of the input-joint revolution. The paper, hence, presents a way of mechanism cycle and reconfiguration analysis based on the configuration torus.

Theoretical Investigations of the Ultrasonic Wave Generation by an Electromagnetic Acoustic Transducer

Background. The article considers the analysis of the electromagnetic acoustic (EMA) converter with controlled angular input of acoustic waves, using parameters influencing the formation of an acoustic wave.Objective. The aim of the paper is to analyze the formation of an acoustic wave with angular input in the EMA converters of non-destructive testing systems.Methods. Mathematical modelling was used to investigate the influence of the distance from the yarn-emitters to the control object surface. The influence of various factors (current magnitudes, external magnetic field values, distance from the yarn-emitter and the grating to the control object surface) is investigated with the help of mathematical modeling.Results. The optimal value of the magnetic induction of an external magnetic field is shown. The calculation of the pressure created by the yarn-emitters and the grating on the controlled object surface was carried out. A formula for the ultrasonic wave input angle was obtained. The formula depends on the parameters of the control environment, the distance between the emitters, the phase shift between the harmonic current signals applied to the adjacent emitters and the harmonic signal frequency. It was found that a change in the angle between the EMA transducer and the surface of the control object leads to a significant deterioration in the acoustic wave generation on the surface of the controlled object.Conclusions. We investigated the possibility of the angular input of an ultrasonic wave using system of parallel-arranged yarn-emitters. A decrease in the acoustic pressure, with increasing distance from the yarn-emitters to the controlled object surface was observed.

Omnidirectional Nonprehensile Manipulation Using Only One Actuator

This paper presents a novel nonprehensile manipulation method that uses the vibration of a plate, where the two degrees of freedom of a part on the plate are controlled by only one actuator. First, a manipulator whose end effector is a flat plate is introduced. By employing an underactuated joint mechanism, the shape and orientation of the vibrational orbit of the plate vary according to frequency and offset angle of the sinusoidal displacement input to an actuator. Then, simulation analyses reveal that the manipulator can omnidirectionally induce translational velocity to the part on the plate. There exists an orthogonality between the effects of the frequency and offset angle on the velocity map of the part. Based on this characteristic, a visual feedback control for manipulating the part is designed. Finally, the proposed method is validated via experiments using a prototype manipulator. A target-trajectory tracking task and a four-way part-feeding task are demonstrated.

Vehicle Dynamics Modeling and Electronic Stability Program/ Active Front Steering Sliding Mode Integrated Control

AbstractChassis integrated control can significantly improve vehicle handling stability and comfort. Because of the complexity of the problem, it has attracted significant research attention. We built a vehicle nonlinear dynamic model with multi‐degree freedom, including body movement, wheel movement, and electronically controlled hydraulic power steering system. We compared the magic formula tire model, Dugoff tire model, brush tire model, and LuGre dynamic friction tire model and steady model. The precision of the model was verified by a comparison between simulation results and the real vehicle test results. Then, based on the vehicle dynamics model, an AFS (active front steering) controller was designed based on sliding mode variable structure control, and an AFS and ESP (electronic stability program) integrated coordination controller was proposed. Finally, based on the nonlinear tire model and multi‐DOF (degree of freedom) vehicle model, sinusoidal and step steering angle input simulation analysis was proposed on different road friction coefficients. The results show that the vehicle has better response characteristics with coordinated control strategy when compared with AFS and ESP only control. The evidence suggests that the proposed integrated control system in this paper can improve vehicle stability and safety.

Microturbine with new design of nozzles

The article presents a new technical solution for designingmicroturbine nozzles. The nozzles have a rectangular cross section, the longitudinal axis of the accelerating section is straight, and its projection onto the plane of the nozzle is placed at a tangent to thecircle formed by the middle diameter of the turbine. This makes it possible to increase the efficiency of the microturbines, which have nozzles with outlet angles from 5° to 9°.Microturbine efficiency research was carried on an experimental turbine. The studied turbine power reached 80 kW. The authors submit an empirical model makes it possible to predict the efficiency of a microturbine and determine the values of the factors corresponding to the maximum efficiency mode. Through optimization, the efficiency of the investigated microturbine stages reached 0.62 with tapered nozzles. The other parameters were: the nozzle outlet angle - 5°; the rotor blade input angle - 8.1°; the dimensionless peripheral speed - 0.44; the degree of pressure reduction per stage - 19.7.

Accuracy and precision of quantitative DCE-MRI parameters: How should one estimate contrast concentration?

IntroductionPharmacokinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) data are sensitive to acquisition and post-processing techniques, which makes it difficult to compare results obtained using different methods. In particular, one of the most important factors affecting estimation of model parameters is how to convert MRI signal intensities to contrast agent concentration. The purpose of our study was to quantitatively compare a linear signal-to-concentration conversion (LC) as an approximation and a non-linear conversion (NLC) based on the MRI signal equation, in terms of the accuracy and precision of the pharmacokinetic parameters in T1-weighted DCE-MRI. Materials and methodsNumerical simulation studies were conducted to compare LC and NLC in terms of the accuracy and precision in contrast kinetic parameter estimation, and to evaluate their dependency on flip angle (FA), pre-contrast T1 (T10) and arterial input function (AIF). In addition, the effect of the conversion method on the diagnostic accuracy was evaluated with 36 breast lesions (19 benign and 17 malignant). ResultsThe transfer rate (Ktrans) estimated using LC and measured AIF (mAIF) were up to 38% higher than the true Ktrans values, while the LC Ktrans estimates with the presumed AIF (pAIF) were up to 7% lower than the true Ktrans values, when FA = 45°. When using a small FA, such as 12°, the LC Ktrans with pAIF had least sensitivity to the error in T10 compared to the Ktrans estimated using LC with mAIF, and NLC with pAIF or mAIF. The breast DCE-MRI study showed that both LC and NLC Ktrans were significantly different (p < 0.05) between the malignant and benign lesions. The effect size between benign and malignant values as measured by Cohen's d was 1.06 for LC Ktrans and 1.02 for NLC Ktrans. ConclusionThe present study results show that, when precontrast T1 measurement is not available and a low FA is used for DCE-MRI, the uncertainty in the contrast kinetic parameter estimation can be reduced by using the LC method with pAIF, without compromising the diagnostic accuracy.

Improved Single-Phase AC–DC–AC Current Source Converter With Reduced DC-Link Oscillation

In this paper, a synchronization technique for single-phase ac–dc–ac current source converters is presented. The technique aims to minimize the double-line-frequency dc-link current oscillation, thus, increasing the power density of the converter. The technique is applied to an improved back-to-back crossed switches current source converter (CSC) named X-type CSC, which presents independent full quadrant operation, lower dc-link current value, higher efficiency when compared with similar ones, and high ac output voltage waveform quality. The deduction of how the dc-link oscillation is influenced by both input and output angles is presented, as well its mitigation. Simulation and experimental results of a 200-W prototype are presented in order to validate the theoretical approach, and to demonstrate the synchronization phenomenon.

Precomputation‐based radix‐4 CORDIC for approximate rotations and Hough transform

Vector rotation is an important component of algorithms in digital signal processing and robotics. Often, the rotation does not require very high accuracy. This study presents a lowoverhead sign-precomputation-based architecture for approximate rotation using the coordinate rotation digital computer (CORDIC) algorithm. The proposed architecture is independent of Z -datapath, and involves precomputation of the direction of rotation for each micro-rotation angle. The approach involves selecting the optimal micro-rotation angles from a set of elementary angles in run time. Careful selection and elimination of the redundant micro-rotation angles leads to a maximum of three iterations for a majority of the input angles while also simultaneously reaching within 0:45 (of the desired rotation angle). An field programmable gate array (FPGA) implementation of the proposed rotation mode CORDIC on XC7K70T-3FBG676 Kintex-7 using Xilinx ISE 13.2 achieves roughly 50% reduction in slice-delay product and power-delay product compared to recent designs. An application of approximate rotation to Hough transform-based lane detection is presented. An efficient algorithm for generation of vote addresses in the parameter space is proposed. It is shown that accurate lane detection is possible along with resource savings using the proposed CORDIC. The proposed architecture reduces the number of additions roughly by a factor of 20 compared with the conventional method of computing a parameter for each feature point.