Position Of Slider Research Articles

Electro-hydraulic servo position control of bending machine based on Single Neuron PID

Abstract Due to the fixed parameters, inadequate dynamic performance, and significant tracking error of the traditional PID control algorithm, it is challenging to satisfy the increasingly stringent precision demands for position control of the slider in the hydraulic servo system of the bending machine. Given the significant impact of external load on the position accuracy of the bending machine’s slider, a single neuron network is employed to dynamically adjust parameters in response to external load interference, thereby compensating for the limitations of traditional algorithms. Consequently, this paper proposes the design of a single neuron PID (SN-PID) controller to enhance system control accuracy. Through multiple simulation comparisons, it is evident that the SN-PID controller system exhibits superior anti-interference capabilities, enhanced adaptability, and reduced following error compared to traditional PID control algorithms in achieving slider position accuracy.

On the locomotion of the slider within a self-adaptive beam–slider system

A beam–slider system is considered whose passive self-adaption relies on an intricate locomotion process involving both frictional and unilateral contact. The system also exploits geometric nonlinearity to achieve broadband efficacy. The dynamics of the system take place on three distinct time scales: On the fast time scale of the harmonic base excitation are the vibrations and the locomotion cycle. On the slow time scale, the slider changes its position along the beam, and the overall vibration level varies. Finally, on an intermediate time scale, strong modulations of the vibration amplitude may take place. In the present work, first, an analytical approximation of the beam’s response on the slow time scale is derived as function of the slider position, which is a crucial prerequisite for identifying the main drivers of the slider’s locomotion. Then, the most important forms of locomotion are described and approximations of their individual contribution to the overall slider transport are estimated. Finally, the theoretical results are compared against numerical results obtained from an experimentally validated model.

High-integrated micro permanent magnet linear actuator positioning system

A tunnel magnetic resistance (TMR) sensor is a magnetic detection sensor with low power consumption and high sensitivity. The TMR sensor has promising applications in the position detection of micro permanent magnet linear actuators since the surrounding magnetic field of the micro actuator in this paper will be changed by its movement. Firstly, according to the air-gap magnetic field distribution characteristics of the micro permanent magnet linear actuator and the detection principle of the TMR sensor, the integrated installation parameters of TMR sensors were determined. Then, with the help of TMR technology, the backpropagation neural network (BPNN) algorithm and improved BPNN using particle swarm optimization (PSO) algorithm were used to study the position identification strategy of the slider, and the algorithm strategy with the minimum error was selected. Finally, the experimental results show that the slider position identification strategy based on the PSO-BPNN algorithm can achieve position tracking error within 0.1 mm under the given step position tracking and sinusoidal position tracking, and the movements can be repeated well.

An L-shaped and bending-torsion coupled beam for self-adaptive vibration energy harvesting

Vibration energy harvesting is promising for powering wireless sensor networks for mechanical equipment monitoring. Considering the broadband feature of ambient vibrations, a novel L-shaped self-adaptive piezoelectric energy harvester (LSA-PEH) with a slider is proposed. A linearized mathematical model of the LSA-PEH is established to obtain the relationship between its resonant frequency and the slider position. The maximum resonant frequency that can be achieved by the LSA-PEH is predicted based on the linearized model. The corresponding condition is to fix the slider at around 0.08 m, which is a nodal point. Moreover, the theoretical model explains why the slider moves back and forth when the excitation frequency is 40 Hz. Experimental results show that the slider of the proposed LSA-PEH can passively relocate its position to adjust its resonant frequency and maintain resonance. By the same criteria, the bandwidth of the proposed LSA-PEH is increased by 350% compared to a conventional L-shaped beam harvester.

On the displacement transferability of variable stiffness multi-directional low frequency vibration isolation joint

In this paper, the proposed variable stiffness vibration isolation joint (VSJ) is refined, and the effects of structural damping and friction are considered and systematically investigated. The VSJ is provided with positive stiffness by the disk spring and negative stiffness by a combination of opposing buckled Euler beams with adjustable lengths to form a quasi-zero stiffness vibration isolation system. The force balance equations of VSJ in horizontal and vertical directions are presented, and the stiffness regulation capability of the structure is discussed. The vibration equations of VSJ are established and the vibration transmission rate under displacement excitation is determined using Taylor expansion and harmonic balance method. Parametric analysis shows that the reasonable configuration of slider position, spring size and stacking form can ensure the low-frequency vibration isolation capability of VSJ under heavy load, and has the ability to adjust the stiffness for different working conditions and loads. The excellent load-bearing capacity, small space footprint, and high customizability and flexibility of the performance of the VSJ give it the potential for a wide range of applications in engineering. We have investigated its adjustable stiffness and vibration isolation performance in the vertical direction by conducting experiments on the prototype to verify the correctness of the theoretical model.

Promoting Music Exploration through Personalized Nudging in a Genre Exploration Recommender

Recommender systems are efficient at predicting users’ current preferences, but how users’ preferences develop over time is still under-explored. In this work, we study the development of users’ musical preferences. Exploring musical preference consistency between short-term and long-term preferences in data from earlier studies, we find that users with higher musical expertise have more consistent preferences for their top-listened artists and tags than those with lower musical expertise, while high expertise users also show more diverse listening behavior. Users typically chose to explore genres that were close to their current preferences, and this effect was stronger for expert users. Based on these findings, we conducted a user study on genre exploration to investigate (1) whether it is possible to nudge users to explore more distant genres, (2) how users’ exploration behavior within a genre is influenced by default recommendation settings that balance personalization with genre representativeness in different ways, and (3) how nudging for exploration increases the perceived helpfulness of recommendations for users to explore. Our results show that users were more likely to select the more distant genres if these genres were nudged by presented at the top of the list, however, users with high musical expertise were less likely to do so. We also find that the more representative default slider, which by default recommended more genre-representative tracks, made users set the slider at a less personalized level. The more representative slider position alone did not promote more exploration of users’ current preferences but when combined with the nudge for distant genres, the more representative slider positions effectively nudged users to explore. Nudging to explore does not necessarily lead to an increase in perceived helpfulness. On the one hand, nudging for exploration improves the perceived helpfulness for exploration by making users explore away from their current preferences. On the other hand, it reduces helpfulness due to lower perceived personalization as users move away from their personalized recommendations. To improve perceived helpfulness, it seems necessary to provide a balanced trade-off between exploration and personalization.

Experimental validation of a model for a self-adaptive beam–slider system

A system consisting of a doubly clamped beam with an attached body (slider) free to move along the beam has been studied recently by multiple research groups. Under harmonic base excitation, the system has the capacity to passively adapt itself (by slowly changing the slider position) to yield either high or low vibrations. The central contributions of this work are the refinement of the recently developed system model with regard to the finite stiffness of the beam’s clamping, followed by a thorough validation of this model against experimental results. With the intent to achieve repeatable and robust self-adaption, a new prototype of the system was designed, featuring, in particular, a continuously adjustable gap size and a concave inner contact geometry. The initial beam model is updated based on the results of an Experimental Nonlinear Modal Analysis of the system (without slider). By varying the excitation level and frequency in a wide range, all known types of behavior were reproduced in the experiment. The simulation results of the updated model with slider are in excellent agreement with the measurements, both qualitatively (type of behavior) and quantitatively. Minor deviations are attributed to the system’s sensitivity to inevitable uncertainties, in particular with regard to the friction coefficient and the linear natural frequency. It is thus concluded that the proposed model is well-suited for further analysis of the system’s intriguing dynamics and for model-based optimization for technical applications such as energy harvesting.

Individualized Scan Protocols in Abdominal Computed Tomography: Radiation Versus Contrast Media Dose Optimization.

In contrast-enhanced abdominal computed tomography (CT), radiation and contrast media (CM) injection protocols are closely linked to each other, and therefore a combination is the basis for achieving optimal image quality. However, most studies focus on optimizing one or the other parameter separately. Reducing radiation dose may be most important for a young patient or a population in need of repetitive scanning, whereas CM reduction might be key in a population with insufficient renal function. The recently introduced technical solution, in the form of an automated tube voltage selection (ATVS) slider, might be helpful in this respect. The aim of the current study was to systematically evaluate feasibility of optimizing either radiation or CM dose in abdominal imaging compared with a combined approach. Six Göttingen minipigs (mean weight, 38.9 ± 4.8 kg) were scanned on a third-generation dual-source CT. Automated tube voltage selection and automated tube current modulation techniques were used, with quality reference values of 120 kVref and 210 mAsref. Automated tube voltage selection was set at 90 kV semimode. Three different abdominal scan and CM protocols were compared intraindividually: (1) the standard "combined" protocol, with the ATVS slider position set at 7 and a body weight-adapted CM injection protocol of 350 mg I/kg body weight, iodine delivery rate (IDR) of 1.1 g I/s; (2) the CM dose-saving protocol, with the ATVS slider set at 3 and CM dose lowered to 294 mg I/kg, resulting in a lower IDR of 0.9 g I/s; (3) the radiation dose-saving protocol, with the ATVS slider position set at 11 and a CM dose of 441 mg I/kg and an IDR 1.3 g I/s, respectively. Scans were performed with each protocol in arterial, portal venous, and delayed phase. Objective image quality was evaluated by measuring the attenuation in Hounsfield units, signal-to-noise ratio, and contrast-to-noise ratio of the liver parenchyma. The overall image quality, contrast quality, noise, and lesion detection capability were rated on a 5-point Likert scale (1 = excellent, 5 = very poor). Protocols were compared for objective image quality parameters using 1-way analysis of variance and for subjective image quality parameters using Friedman test. The mean radiation doses were 5.2 ± 1.7 mGy for the standard protocol, 7.1 ± 2.0 mGy for the CM dose-saving protocol, and 3.8 ± 0.4 mGy for the radiation dose-saving protocol. The mean total iodine load in these groups was 13.7 ± 1.7, 11.4 ± 1.4, and 17.2 ± 2.1 g, respectively. No significant differences in subjective overall image or contrast quality were found. Signal-to-noise ratio and contrast-to-noise ratio were not significantly different between protocols in any scan phase. Significantly more noise was seen when using the radiation dose-saving protocol (P < 0.01). In portal venous and delayed phases, the mean attenuation of the liver parenchyma significantly differed between protocols (P < 0.001). Lesion detection was significantly better in portal venous phase using the CM dose-saving protocol compared with the radiation dose-saving protocol (P = 0.037). In this experimental setup, optimizing either radiation (-26%) or CM dose (-16%) is feasible in abdominal CT imaging. Individualizing either radiation or CM dose leads to comparable objective and subjective image quality. Personalized abdominal CT examination protocols can thus be tailored to individual risk assessment and might offer additional degrees of freedom.

Make the mechanical model for rotational-to-linear motion transformer using a double eccentric crank

A mechanism converting straight to cycle motion, for example a slider-crank mechanism is used for internal combustion engine. The research group suggested the Rotational-to-Linear motion Transformer using a Double eccentric Crank (RLTDC) as new mechanism convert straight to cycle motion. This mechanism is developed based on Oldham coupling (double-slider mechanism) and slider-crank mechanism, which can be expect for size down machines using a mechanism convert straight to cycle motion because stroke is double comparing a slider-crank mechanism on equal crank length. But, from the experimental measured value of the kinetic load in the preceding study, the matter that the durability of a slider guide would be concerned is revealed. So，the relationship between the peak value of load acting on the slider guide and the slider position is needed to be clarified. In this study, the process making the mechanical model for this relationship is shown.

Position estimation of synchronous electrostatic film motors under pulse-voltage operation by using driving currents

Synchronous electrostatic film motors under pulse-voltage operation require position estimation, as it is unavoidable to step out from synchronization due to unexpected large external disturbance. However, the existing position estimation method using driving currents can only work well under sine-voltage operation and fails with a huge error for the pulse-voltage operation due to the impulsive currents at the switching time of the pulse-voltage. This work proposes a new position estimation method dedicated for the pulse-voltage operation, which is mainly used to track the slider position at out-of-step. The impulse currents is removed directly in this method, however, the removal period affects the estimation performance since some essential information of position can also be removed. Theoretically, as long as the information loss is less than a certain level, the proposed method can always work well. Simulation results confirmed that the slider position can be estimated correctly with a resolution of an electrode pitch if the duration of the impulsive currents is short. Experiments under various conditions were carried out by using a real motor, and the results verified that the proposed method can not only successfully track the slider position at out-of-step, but also during synchronous operation.

A capsule-structured triboelectric energy harvester with stick-slip vibration and vibro-impact

Despite great progress made in triboelectric energy harvesting, most investigations are purely about experiments and/or manufacturing. There is a serious lack of in-depth theoretical studies of the underlying vibration and its effects on power yield. In this paper, a novel triboelectric energy harvester is presented and its non-smooth structural dynamics and electrical performance are studied. This first theoretical study of a capsule-structured triboelectric energy harvester includes a mathematical model coupling the structural dynamics and electric dynamics, which integrates in-plane sliding mode and contact-separation mode. The influences of friction properties on sliding surfaces, electrostatic force, initial slider position, excitation level and harvester dimensions, are investigated. The performance of this harvester is not limited by its frequency bandwidth, whose average power increases from 10.3 μW at 3 Hz to 69.4 μW at 14 Hz. Impact/chatter events are found to improve power yield, for example, there is a dramatic increase of 20 μW at 6 Hz due to impact induced by a slight increase of excitation amplitude. Additionally, the internal capsule length plays a subtle role and a length beyond a certain value causes a sharp fall of power yield. These findings enable innovative designs and provide fabrication guidelines of triboelectric energy harvesters.

The influence of a slider gap in the beam\u2013slider structure with an MFC element on energy harvesting from the system: experimental case

A passively self-tuning resonator configuration is presented in this study. Under certain operating conditions, a self-resonating system has the capability to passively adjust dynamical characteristics until the whole system becomes resonant. A clamped–clamped beam with an attached mass sliding along the beam and a slight gap that, under a harmonic input excitation and well-defined operating regime, can lead to the increase in voltage amplitude generated by the piezo-harvester attached to this structure may be an example of such a system. Taking into account such behavior of the system, the paper is focused on determining the distributed-parameters of the electromechanical system versus a different slider position on the beam in modal coordinates. The obtained simulation results, considering the homogenous model of an MFC element for the desired slider locations, showed how the width of the gap between the slider and the beam additionally influences the voltage generated by the piezo-harvester. Experimental tests carried out on the real stand with an EHE301 module and the designed SSHI interface circuit allowed to verify the numerical results and also showed the influence on the resistive load connected to the system for an improvement of the considered energy harvesting system parameters.

Optimization-Based Investigation of Bioinspired Variable Gearing of the Distributed Actuation Mechanism to Maximize Velocity and Force

Transmission between high speed and high force motions is a classic, but challenging problem for most engineering disciplines as well as robotics. This study optimizes the performances (i.e., both velocity and force) of the distributed actuation mechanism (DAM) based on the novel concept of continuously variable gearing, which is inspired by muscle movement. To quantify continuously variable gearing in the DAM, the structural gear ratio (defined as joint speed/motor speed) is mathematically derived in terms of the slider position and the joint angle. Then, for a DAM-based three-revolute joint manipulator, a multi-objective optimization problem is formulated to determine the maximum end-effector velocity according to varying payloads. An optimization framework consisting of the analysis and optimization modules is constructed to verify the proposed concept with a comparison of an equivalent joint actuation mechanism (JAM)-based three-revolute joint manipulator. The numerical results demonstrate that the bioinspired variable gearing of the DAM allows for a significant enhancement of end-effector velocity and force, depending on a given task.

Explanation of the self-adaptive dynamics of a harmonically forced beam with a sliding mass

The self-adaptive behavior of a clamped–clamped beam with an attached slider has been experimentally demonstrated by several research groups. In a wide range of excitation frequencies, the system shows its signature move: The slider first slowly moves away from the beam’s center, at a certain point the vibrations jump to a high level, then the slider slowly moves back toward the center and stops at some point, while the system further increases its high vibration level. In our previous work, we explained the unexpected movement of the slider away from the beam’s vibration antinode at the center by the unilateral and frictional contact interactions permitted via a small clearance between slider and beam. However, this model did not predict the signature move correctly. In simulations, the vibration level did not increase significantly and the slider did not turn around. In the present work, we explain, for the first time, the complete signature move. We show that the timescales of vibration and slider movement along the beam are well separated, such that the adaptive system closely follows the periodic vibration response obtained for axially fixed slider. We demonstrate that the beam’s geometric stiffening nonlinearity, which we neglected in our previous work, is of utmost importance for the vibration levels encountered in the experiments. This stiffening nonlinearity leads to coexisting periodic vibration responses and to a turning point bifurcation with respect to the slider position. We associate the experimentally observed jump phenomenon to this turning point and explain why the slider moves back toward the center and stops at some point.

Design, modelling and experimentation of a novel compliant translational dwell mechanism

A partially compliant novel translational double dwell mechanism is presented in this article. The designed mechanism consists of initially straight and preloaded pinned-pinned compliant links, rigid crank, slider-rail system and a DC motor. Slider doesn’t move until the critical buckling load is achieved and then snaps to its maximum and returns back to initial position as the crank completes a full rotation. Motion behavior of elastic members depending on the geometry and loading are investigated using Elastica theory. Kinematic analysis and dynamical model are obtained by representing the compliant pinned-pinned members as translational springs using polynomial formulation method. Mechanism behavior is also analyzed in Adams FlexView. Mechanism is built by 3D printing the flexible parts using polylactic acid (PLA). Displacement of the slider along with the deformation of buckling beams are recorded and deflection shapes are detected by machine vision measurement while the crank is subjected to complete rotation. Slider position is also recorded by a laser displacement sensor. Dynamical model results are validated by the experimental setup, machine vision measurement and Adams simulations.

Slider position control for slider-crank mechanisms with Jacobian compensator

In this work, a position control for slider-crank mechanisms without Jacobian and joint measurements is presented. A Jacobian compensator that depends on the sign of the direction of rotation of the input link and the output link is proposed. A linear sensor is mounted at the slider to measure its position. Simulations and experiments are presented using two different Whitworth mechanisms to validate and compared the proposed approach with Jacobian-based controllers.

Crowd wisdom enhanced by costly signaling in a virtual rating system

Costly signaling theory was developed in both economics and biology and has been used to explain a wide range of phenomena. However, the theory's prediction that signal cost can enforce information quality in the design of new communication systems has never been put to an empirical test. Here we show that imposing time costs on reporting extreme scores can improve crowd wisdom in a previously cost-free rating system. We developed an online game where individuals interacted repeatedly with simulated services and rated them for satisfaction. We associated ratings with differential time costs by endowing the graphical user interface that solicited ratings from the users with "physics," including an initial (default) slider position and friction. When ratings were not associated with differential cost (all scores from 0 to 100 could be given by an equally low-cost click on the screen), scores correlated only weakly with objective service quality. However, introducing differential time costs, proportional to the deviation from the mean score, improved correlations between subjective rating scores and objective service performance and lowered the sample size required for obtaining reliable, averaged crowd estimates. Boosting time costs for reporting extreme scores further facilitated the detection of top performances. Thus, human collective online behavior, which is typically cost-free, can be made more informative by applying costly signaling via the virtual physics of rating devices.

Feasibility and Accuracy of Automated Software for Transthoracic Three-Dimensional Left Ventricular Volume and Function Analysis: Comparisons with Two-Dimensional Echocardiography, Three-Dimensional Transthoracic Manual Method, and Cardiac Magnetic Resonance Imaging

Recently, a new automated software package (HeartModel) was developed to obtain three-dimensional (3D) left ventricular (LV) volumes using a model-based algorithm (MBA) with a "one-button" simple system and user-adjustable slider. The aims of this study were to verify the feasibility and accuracy of the MBA in comparison with other commonly used imaging techniques in a large unselected population, to evaluate possible accuracy improvements of free operator border adjustments or changes of the slider's default position, and to identify differences in method accuracy related to specific pathologies. This prospective study included consecutive 200 patients. LV volumes and ejection fraction were obtained using the MBA and compared with the two-dimensional biplane method, the 3D full-volume (3DFV) modality, and, in 90 of 200 cases, cardiac magnetic resonance (CMR) measurements. To evaluate the optimal position of the slider with respect to the 3DFV and CMR modalities, a set of threefold cross-validation experiments was performed. Optimized and manually corrected LV volumes obtained using the MBA were also tested. Linear correlation and Bland-Altman analysis were used to assess intertechnique agreement. Automatic volumes were feasible in 194 patients (94.5%), with a mean processing time of 29±10sec. MBA-derived volumes correlated significantly with all evaluated methods, with slight overestimation of two-dimensional biplane and slight underestimation of CMR measurements. Higher correlations were found between MBA and 3DFV measurements, with negligible differences both in volumes (overestimation) and in LV ejection fraction (underestimation), respectively. Optimization of the user-adjustable slider position improved the correlation and markedly reduced the bias between the MBA and 3DFV or CMR. The accuracy of MBA volumes was lower in some pathologies for incorrect definition of LV endocardium. The MBA is highly feasible, reproducible, and rapid, and it correlates highly with the traditional 3DFV method. It may represent a valid alternative to 3DFV measurement for everyday clinical use.

Investigation on a mechanical vibration absorber with tunable piecewise-linear stiffness

Abstract The design and characterization of a mechanical vibration absorber are addressed. A distinctive feature of the absorber is its tunable piecewise-linear stiffness, which is realized by means of a slider with two stop-blocks installed constraining the bilateral deflections of the elastic support. A new analytical approach named as the equivalent stiffness technique (EST) is introduced and then employed to obtain the analytical relations of the frequency, amplitude and phase with a view to exhibit a more comprehensive characterization of the absorber. Experiments are conducted to demonstrate the feasibility of the design. The experimental data show good agreement with the analytical results. The final results indicate that the tunable stiffness absorber (TSA) possesses a typical nonlinear characteristic at each given position of the slider, and its stiffness can be tuned in real time over a wide range by adjusting the slider position. Hence the TSA has a large optimum vibration-absorption range together with a wide suppression band around each optimal position, which contributes to its excellent capacity of vibration absorption.

Experimental study of the influence levels of different vehicle seat adjustments on the fore-and-aft modal characteristics using the orthogonal array method

The vehicle seat modal characteristics (in particular, the first resonant frequency and the corresponding modal shape) play important roles in the seat design and the ride comfort. This paper investigated the relationship between the first modal characteristics and the positions of the adjusters on the vehicle seat. There are four adjusters on the vehicle seat to change its position so as to match the driver’s somatotype, the driving and the sitting habits. Different seat positions inevitably cause changes in the resonant frequency. An orthogonal array method was adopted to evaluate the influence levels of the adjusters by using a Pareto chart. It was found that the first modal (fore-and-aft) shape is almost uninfluenced by the variations in the adjuster positions, whereas the first modal frequency is greatly influenced by the changes in the adjuster positions. The first modal frequency is most affected by the variation in the slider position, followed by the variation in the headrest adjuster position, the variation in the recliner position and the variation in the height adjuster position.